LIBRARY 
 
 UNIVERSITY OF CALIFORNIA. 
 
 Class 
 

Masonry Construction 
 
 A Guide to 
 
 APPROVED AMERICAN PRACTICE IN THE SELECTION OF BUILDING STONE, 
 
 BRICK, CEMENT, AND OTHER MASONRY MATERIALS, AND IN ALL 
 
 BRANCHES OF THE ART OF MASONRY CONSTRUCTION 
 
 By ALFRED E. PHILLIPS, C.E., PH.D. 
 
 Professor of Civil Engineering, Armour Institute of Technology 
 
 and 
 AUSTIN T. BYRNE 
 
 Civil Engineer. Author of " Highway Construction," 
 " Materials and Workmanship" 
 
 ILLUSTRATED 
 
 CHICAGO 
 
 AMERICAN SCHOOL OF CORRESPONDENCE 
 1908 
 
COPYRIGHT 1907 BY 
 AMERICAN SCHOOL OF CORRESPONDENCE 
 
 Entered at Stationers' Hall, London 
 All Rights Reserved 
 
Foreword 
 
 recent years, such marvelous advances have been 
 made in the engineering and scientific fields, and 
 so rapid has been the evolution of mechanical and 
 constructive processes and methods, that a distinct 
 need has been created for a series of practical 
 'working guides, of convenient size and low cost, embodying the 
 accumulated results of experience and the most approved modern 
 practice along a great variety of lines. To fill this acknowledged 
 need, is the special purpose of the series of "handbooks to which 
 this volume belongs. 
 
 C, In the preparation of this series, it has been the aim of the pub- 
 lishers to lay special stress on the practical side of each subject, 
 as distinguished from mere theoretical or academic discussion. 
 Each volume is written by a well-known expert of acknowledged 
 authority in his special line, and is based on a most careful study 
 of practical needs and up-to-date methods as developed under the 
 conditions of actual practice in the field, the shop, the mill, the 
 power house, the drafting room, the engine room, etc. 
 
 C, These volumes are especially adapted for purposes of self- 
 instruction and home study. The utmost care has been used to 
 bring the treatment of each subject within the range of the com- 
 
 1 73042 
 
mon understanding, so that the work will appeal not only to the 
 technically trained expert, but also to the beginner and the self- 
 taught practical man who wishes to keep abreast of modern 
 progress. The language is simple and clear; heavy technical terms 
 and the formulae of the higher mathematics have been avoide^d, 
 yet without sacrificing any of the requirements of practical 
 instruction; the arrangement of matter is such as to carry the 
 reader along by easy steps to complete mastery of each subject; 
 frequent examples for practice are given, to enable the reader to 
 test his knowledge and make it a permanent possession; and the 
 illustrations are selected with the greatest care to supplement and 
 make clear the references in the text. 
 
 C. The method adopted in the preparation of these volumes is that 
 which the American School of Correspondence has developed and 
 employed so successfully for many years. It is not an experiment, 
 but has stood the severest of all tests that of practical use which 
 has demonstrated it to be the best method yet devised for the 
 education of the busy working man. 
 
 C, For purposes of ready reference and timely information when 
 needed, it is believed that this series of handbooks will be found to 
 meet every requirement. 
 
T a b 1 e * o .f Contents 
 
 STRUCTURAL MATERIALS . . . - . , . . . . Page 1 
 
 Classification of Natural Stones Requisites of Good Building Stone 
 Tests for Stone (Absorptive Power, Effect of Frost, Atmosphere, Re- 
 sistance to Crushing-, etc.) Preservation of Stone Artificial Stones 
 Brick and Its Manufacture Color of Bricks Classification of Brick 
 Size and Weight of Brick Resistance to Crushing of Brick Fire- 
 brick Cementing Materials Common Lime Hydraulic Lirne Rosen- 
 dale or Natural Cement Portland Cement Testing Cement (Color, 
 Weight, Fineness, Activity, Soundness, Cold Tests, Warm- Water Test, 
 Strength, Briquettes for Testing) Preservation of Cements Slag 
 Cement Pozzuolanas Roman Cement Mortar (Ordinary, Cement) 
 Retempering Mortar Freezing of Mortar Concrete Proportions of 
 Materials Mixing and Laying Concrete Asphaltic Concrete Clay 
 Puddle. 
 
 FOUNDATION WORK . .... C ... . . . Page 39 
 
 Natural Foundations Artificial Foundations Pile Foundations 
 Timber Piles Iron and Steel Piles Screw Piles Concrete Piles 
 Pile-Driving Splicing Piles Concrete- Steel Foundations Caissons 
 Cofferdams Sheet Piles Cribs Freezing Process Designing the 
 Foundation Weight of Masonry Bearing Power of Soils Design 
 of Footings (Stone, Timber, Steel I-Beams) Safe Working Loads. 
 
 STONEWORK AND BRICKWORK . .... ... .. . ." . Page 63 
 
 Classification of Masonry Glossary of Terms Used in Masonry 
 Dressing the Stones Tools Used in Stonecutting Glossary of Terms 
 Used in Stonecutting Finishing Faces of Cut Stone Unsquared, 
 Squared, and Cut Stones Ashlar Masonry Squared-Stone Masonry 
 Broken Ashlar Rubble Masonry Ashlar Backed with Rubble Gen- 
 eral Rules for Laying Masonry of Stone; of Brick Face or Pressed- 
 Brick Work Brick Masonry Impervious to Water Efflorescence 
 Repair of Masonry. 
 
 MASONRY STRUCTURES . . . . . . f _ . . . Page 89 
 
 Walls Retaining Walls Dimensions and Proportions of Walls 
 WeepHoles Surcharged Walls Kinds of Arches Glossary of Terms 
 Used in Arch Construction Dimensions of Arches Flat Arches 
 Relieving Arches Construction of Arches Centering for Arches 
 Bridge Abutments Bridge Piers Box Culverts Arch Culverts 
 Wing Walls Concrete Blocks Concrete-Steel Masonry. 
 
 INDEX . . ' .. . . . , v > . . . . Page 119 
 
w be 
 
 s 
 
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 N ^ 
 
MASONRY CONSTRUCTION. 
 
 PART I. 
 
 STRUCTURAL MATERIALS. 
 
 Classification of Natural Stones. The rocks from which the 
 stones for building are selected are classified according to (1) their 
 geological position, (2) their physical structure, and (3) their chemical 
 composition. 
 
 Geological Classification. The geological position of rocks 
 has but little connection with their properties as building materials. 
 As a general rule, the more ancient rocks are the stronger and more 
 durable; but to this there are many notable exceptions. According 
 to the usual geological classification rocks are divided into three 
 classes, viz. : 
 
 Igneous, of which greenstone (trap), basalt, and lava are ex- 
 amples. 
 
 Metamorphic, comprising granite, slate, marble, etc. 
 
 Sedimentary, represented by sandstones, limestones, and clay. 
 
 Physical Classification. With respect to the structural char- 
 acter of their large masses, rocks are divided into two great classes: 
 (1) the unstratified, (2) the stratified, according as they do or do not 
 consist of flat layers. 
 
 The unstratified rocks are for the most part composed of an 
 aggregation of crystalline grains firmly cemented together. Granite, 
 trap, basalt, and lava are examples of this class. All the unstratified 
 rocks are composed as it were of blocks which separate from each 
 other when the rock decays or when struck violent blows. These 
 natural joints are termed the line of cleavage or rift, and in all cutting 
 or quarrying of unstratified rocks the work is much facilitated by 
 taking advantage of them. 
 
 The stratified rocks consist of a series of parallel layers, evidently 
 deposited from water, and originally horizontal, although in most 
 cases they have become more or less inclined and curved by the action 
 of disturbing forces. It is easier to divide them at the planes of divi- 
 
MASONRY CONSTRUCTION 
 
 sion between these layers than elsewhere. Besides its principal layers 
 or strata, a mass of stratified rock is in general capable of division into 
 thinner layers; and, although the surfaces of division of the thinner lay- 
 ers are often parallel to those of the strata, they are also often oblique 
 or even perpendicular to them. This constitutes a laminated structure. 
 
 Laminated stones resist pressure more strongly in a direction 
 perpendicular to their laminae than parallel to them; they are more 
 tenacious in a direction parallel to their lamina? than perpendicular 
 to them; and they are more durable with the edges than with the 
 sides of their laminae exposed to the weather. Therefore in building 
 they should be placed with their laminae or "beds" perpendicular 
 to the direction of greatest pressure, and with the edges of these 
 laminae at the face of the wall. 
 
 Chemical Classification. The stones used in building are 
 divided into three classes, each distinguished by the predominant 
 mineral which forms the chief constituent, viz. : 
 
 Silicious stones, of which granite, gneiss, and trap are examples, 
 
 Argillaceous stones, of which clay, slate, and porphyry are 
 examples. 
 
 Calcareous stones, represented by limestones and marbles. 
 
 REQUISITES FOR GOOD BUILDING STONE. 
 
 The requisites for good building stone are durability, strength, 
 cheapness, and beauty. 
 
 Durability. The durability of stone is a subject upon which 
 there is very little reliable knowledge. The durability will depend 
 upon the chemical composition, physical structure, and the position 
 in which the stone is placed in the work. The same stone will vary 
 greatly in its durability according to the nature and extent of the 
 atmospheric influences to which it is subjected. 
 
 The sulphur acids, carbonic acid, hydrochloric acid, and traces 
 of nitric acid, in the smoky air of cities and towns, and the carbonic- 
 acid in the atmosphere ultimately decompose any stone of which 
 either carbonate of lime or carbonate of magnesia forms a consid- 
 erable part. 
 
 Wind has a considerable effect upon the durability of stone. 
 High winds blow sharp particles against the face of the stone and 
 thus grind it away. Moreover, it forces the rain into the pores of 
 
MASONRY CONSTRUCTION 
 
 the stone, and may thus cause a considerable* depth to be subject 
 to the effects of acids and frost. 
 
 In winter water penetrates porous stones, freezes, expands, and 
 disintegrates the surface, leaving a fresh surface to be similarly 
 acted upon. 
 
 Strength is generally an indispensable attribute, especially 
 under compression and cross-strain. 
 
 Cheapness is influenced by the ease with, which the stone can 
 be quarried and worked into the various forms required. Cheapness 
 is also affected by abundance, facility of transportation, and prox- 
 imity to the place of use. 
 
 Appearance. The requirement of beauty is that it should 
 have a pleasing appearance. For this purpose all varieties contain- 
 ing much iron should be rejected, as they are liable to disfigurement 
 from rust-stains caused by the oxidation of the iron under the influ- 
 ence of the atmosphere. 
 
 TESTS FOR STONE. 
 
 The relative enduring qualities of different stones are usually 
 ascertained by noting the weight of water they absorb in a given 
 time. The best stones as a rule absorb the smallest amount of water. 
 
 Some stones, however, come from the quarry soaked with water 
 and in that condition are very soft and easily worked. Upon expo- 
 sure to the atmosphere they gradually dry out and become very hard 
 and durable. The Bedford limestone of Indiana forms an example 
 of this kind of stone, and the stone in many of the public buildings 
 throughout the United States may be seen in the process of "weath- 
 ering", indicated by the mottled appearance of the walls. 
 
 To determine the absorptive power, dry a specimen and weigh 
 it carefully, then immerse it in water for 24 hours and weigh again. 
 The increase in weight will be the amount of absorption. 
 
 TABLE 1. 
 Absorptive Power of Stones. 
 
 Percentage of Water 
 Absorbed. 
 
 Granites 0.00 to 0. 15 
 
 Sandstones 0.41 " 5.48 
 
 Limestones 0.20 " 5.00 
 
 Marbles , . 0.08 " 0.16 
 
MASONRY CONSTRUCTION 
 
 Effect of Frost (Brard's Test). To ascertain the effect of 
 frost, small pieces of the stone are immersed in a concentrated boiling 
 solution of sulphate of soda (Glauber's salts), and then hung up for 
 a few days in the air. The salt crystallizes in the pores of the stone, 
 sometimes forcing off bits from the corners and arrises, and occa- 
 sionally detaching larger fragments. 
 
 The stone is weighed before and after submitting it to the test. 
 The difference of weight gives the amount detached by disintegra- 
 tion. The greater this is, the worse is the quality of the stone. 
 
 Effect of the Atmosphere (Acid Test). Soaking a stone 
 for several days in water containing i per cent of sulphuric and 
 hydrocholric acids will afford an idea as to whether it will stand 
 the atmosphere of a large city. If the stone contains any matter 
 likely to be dissolved by the gases of the atmosphere, the water 
 will be more or less cloudy or muddy. 
 
 A drop or two of acid on the surface of a stone will create an in- 
 tense effervescence if there is a large proportion present of carbon- 
 ate of lime or magnesia. 
 
 PRESERVATION OF STONE. 
 
 A great many preparations have been used for the prevention 
 of the decay of building stones, as paint, coal-tar, oil, beeswax, 
 rosin, paraffine, soft-soap, soda, etc. All of the methods are expen- 
 sive, and there is no evidence to show that they afford permanent 
 protection to the stone- 
 
 ARTIFICIAL STONES. 
 
 Brick is an artificial stone made by submitting clay, which lias 
 been suitably prepared and moulded into shape, to a teftiperature 
 of sufficient intensity to convert it into a semi-vitrified state. The 
 quality of the brick depends upon the kind of clay used and upon 
 the care bestowed on its preparation. 
 
 The clays of which brick is made are chemical compounds con- 
 sisting of silicates of alumina, either alone or combined with other 
 substances, such as iron, lime, soda, potash, magnesia, etc., all of 
 which influence the character and quality of the brick, according as 
 one or the other of those substances predominates. 
 
MASONRY CONSTRUCTION 
 
 TABLE 2. 
 Specific Gravity, Weight and Resistance to Crushing of Stones. 
 
 Kinds of Stone 
 
 Specific Gravity 
 
 Weight, pounds 
 per cubic foot 
 
 Resistance to 
 crushing, pounds 
 per sq. in. 
 
 Granite 
 minimum . . 
 
 2.60 
 
 163 
 
 12,000 
 
 maximum.. . 
 
 2.80 
 
 176 
 
 35,000 
 
 Trap- 
 
 minimum . 
 
 2 86 
 
 178 
 
 19000 
 
 maximum 
 Gneiss average 
 
 3.03 
 2 70 
 
 189 
 
 168 
 
 24,000 
 19600 
 
 Syenite, average . 
 
 2.64 
 
 167 
 
 30,740 
 
 Sandstones 
 minimum . 
 
 2.23 
 
 137 
 
 5,000 
 
 maximum.. 
 
 2 75 
 
 170 
 
 18,000 
 
 Limestones 
 minimum 
 
 1 90 
 
 118 
 
 7000 
 
 maximum 
 
 2 75 
 
 175 
 
 20000 
 
 Marbles 
 minimum ... 
 
 2.62 
 
 165 
 
 8,000 
 
 maximum.. 
 
 2.95 
 
 179 
 
 20,000 
 
 
 
 
 
 Iron gives hardness and strength; hence the red brick of the 
 Eastern States is often of better quality than the white and yellow 
 brick made in the West, Silicate of lime renders the clay too fusible 
 and causes the bricks to soften and to become distorted in the pro- 
 cess of burning. Carbonate of lime is at high temperatures changed 
 into caustic lime, renders the clay fusible, and when exposed to the 
 action of the weather absorbs moisture, promotes disintegration, and 
 prevents the adherence of the mortar. Magnesia exerts but little 
 influence on the quality; in small quantities it renders the clay fusible; 
 at 60 F. its crystals lose their water of crystallization, and cold water 
 decomposes them, forming an insoluble hydrate in the form of a white 
 powder. In air-dried brick this action causes cracking. The alkalies 
 are found in small quantities in the best of clays; their presence tends 
 to promote softening, and this goes on the more rapidly if it has 
 been burned at too low a temperature. Sand mixed with the clay 
 .in moderate quantity (one part of sand to four of clay is about the 
 best proportion) is beneficial, as tending to prevent excessive shrinking 
 in the fire. Excess of sand destroys the cohesion and renders the 
 brick brittle and weak. 
 
MASONRY CONSTRUCTION 
 
 MANUFACTURE OF BRICK. 
 
 The manufacture of brick may be classified under the following 
 heads : 
 
 Excavation of Ihc clay, either by manual or mechanical power. 
 
 Preparation of ihe clay consists in (a) removing stones and me- 
 chanical impurities; (b) tempering and moulding, which is now 
 done almost wholly by machinery. There is a great variety of 
 machines for tempering and moulding the clay, which, however, 
 may be grouped into three classes, according to the condition of 
 the clay when moulded: (1) soft-mud machines, for which the clay 
 is reduced to a soft mud by adding about one quarter of its volume 
 of water; (2) stiff-mud machines, for which the clay is reduced to 
 a stiff mud; (3) dry-clay machines, with which the dry or nearly dry 
 clay is forced into the moulds by a heavy pressure without having 
 been reduced to a plastic mass. These machines may also be divided 
 into two classes, according to the method of filling the moulds: (1) 
 those in w r hich a continuous stream of clay is forced from the pug- 
 mill through a die and is afterwards cut up into bricks; and (2) those 
 in which the clay is forced into moulds moving under the nozxle of 
 the pug-mill. 
 
 Drying and Burning. The bricks, having been dried in the 
 open air or in a drying-house, are burned in kilns; the time of burn- 
 ing varies with the character of the clay, the form and si/e of the kiln, 
 and the kind of fuel, from six to fifteen days. 
 
 Color of Bricks depends upon the composition of the clay, 
 the moulding sand, temperature of burning, and volume of air ad- 
 mitted to the kiln. Pure clay free of iron w r ill burn white, and 
 mixing of chalk w r ith the clay will produce a like effect. Iron pro- 
 duces a tint ranging from red and orange to light yellow, according to 
 the proportion of the iron. 
 
 A large proportion of oxide of iron mixed with pure clay will 
 produce a bright red, and where there is from S to 10 per cent, and 
 the brick is exposed to an intense heat, the oxide fuses and produces a 
 dark blue or purple, and with a small volume of manganese and an 
 increased proportion of the oxide the color is darkened even to a black. 
 
 A small volume of lime and iron produces a cream color, an in- 
 crease of iron produces red, and an increase of lime brutrn Magnesia 
 
MASONRY CONSTRUCTION 
 
 in presence of iron produces yellow, and clay containing alkalies and 
 burned at a high temperature produces a bluish green. 
 
 The best quality of building brick arid probably the majority 
 of paving brick or block, are manufactured from shale. The process 
 of manufacture is similar to that of clay-brick, the shale being first 
 ground very fine. If the shale is nearly free from impurities, the 
 resulting product will be a cream colored brick. To give the brick 
 any desired color, the shale is mixed with clay containing the proper 
 proportions of lime, iron, or magnesia, giving almost any shade from 
 a cream to a dark wine color or even a black. 
 
 Classification of Brick. Bricks are classified according to (1) 
 the way in which they are moulded; (2) their position in the kiln 
 while being burned; and (3) their form or use. 
 
 The method of moulding gives rise to the following terms: 
 
 Soft-mud Brick. One moulded from clay which has been re- 
 duced to a soft mud by adding water. It may be either hand-moulded 
 or machine-moulded. 
 
 Stiff-mud Brick. One moulded from clay in the condition of 
 stiff mud. It is always machine-moulded. 
 
 Pressed Brick. One moulded from dry or semi-dry clay. 
 
 Re-pressed Brick. A soft-mud brick which, after being par- 
 tially dried, has been subjected to an enormous pressure. It is also 
 called, but less appropriately, pressed brick. The object of the 
 re-pressing is to render the form more regular and to increase the 
 strength and density. 
 
 Sanded Brick. Ordinarily, in making soft-mud brick, sand 
 is sprinkled into the moulds to prevent the clay from sticking; the 
 brick is then called sanded brick. The sand on the surface is of 
 no advantage or disadvantage. In hand-moulding, when sand is 
 used for this purpose, it is certain to become mixed with the clay 
 and occur in streaks in the finished brick, which is very undesirable. 
 
 Machine-made Brick. Brick is frequently described as " machine 
 made"; but this is very indefinite, since all grades and kinds are 
 made by machinery. 
 
 When brick was generally burned in the old-style up-draught 
 kiln, the classification according to position was important; but with 
 the new styles of kilns and improved methods of burning, the quality 
 is so nearly uniform throughout the kiln that the classification is less 
 
MASONRY CONSTRUCTION 
 
 important. Three grades of brick are taken from the old-style kiln: 
 
 Arch or Clinker Bricks. Those which form the tops and sides 
 of the arches in which the fire is built. Being overburned and par- 
 tially vitrified, they are hard, brittle, and weak. 
 
 Body, Cherry, or Hard Bricks. Those taken from the interior 
 of the pile. The best bricks in the kiln. 
 
 Salmon, Pale, or Soft Bricks. . Those which form the exterior 
 of the mass. Being imderburned, they are too soft for ordinary 
 work, unless it be for filling. The terms salmon and pale refer to the 
 color of the brick, and hence are not applicable to a brick made of a 
 clay that does not burn red. Although nearly all brick-clays burn 
 red, yet the localities where the contrary is true are sufficiently numer- 
 ous to make it desirable to use a different term in designating the 
 quality. There is not necessarily any relation between color, and 
 strength and density. Brick-makers naturally have a prejudice 
 against the term soft brick, which doubtless explains the nearly uni- 
 versal prevalence of the less appropriate term salmon. 
 
 The form or use of bricks gives rise to the following classification : 
 
 Compass Brick. Those having one edge shorter than the other. 
 Used in lining shafts, etc. 
 
 Feather-edge Brick. Those of which one edge is thinner than 
 the other. Used in arches; and more properly, but less frequently, 
 called voussoir brick. 
 
 Front or Face Brick. Those which, owing to uniformity of size 
 and color, are suitable for the face of the walls of buildings. Some- 
 times face bricks are simply the best ordinary brick; but generally 
 the term is applied only to re-pressed or pressed brick made especially 
 for this purpose. They are a little larger than ordinary bricks. 
 
 Sewer Brick. Ordinary hard brick, smooth, and regular in form. 
 
 Kiln-run Brick. All the brick that are set in the kiln when 
 burned. 
 
 Hard Kiln-run Brick. Brick burned hard enough for the face 
 of outside walls, but taken from the kiln unselected. 
 
 Rank of Bricks. In regularity of form re-pressed brick ranks 
 first, dry-kiln brick next, then stiff-mud brick, and soft-mud brick 
 last. Regularity of form depends largely upon the method of burning. 
 
 The compactness and uniformity of texture, which greatly in- 
 fluence the durability of brick, depend mainly upon the method of 
 
MASONRY CONSTRUCTION 
 
 moulding. As a general rule, hand-moulded bricks are best in this 
 respect, sine the clay in them is more uniformly tempered before 
 being moulded; but this advantage is partially neutralized by the 
 presence of sand-seams. Machine-moulded soft-mud bricks rank 
 next in compactness and uniformity of texture. Then come machine- 
 moulded stiff-mud bricks, which vary greatly in durability with the 
 kind of machine used in their manufacture. By some of the machines 
 the brick is moulded in layers (parallel to any face, according to the 
 kind of machine) which are not thoroughly cemented, and which 
 separate under the action of frost. The dry-clay brick comes last. 
 However, the relative value of the products made by different pro- 
 cesses varies with the nature of the clay used. 
 
 TABLE 3. 
 Size and Weight of Bricks. 
 
 The variations in the dimensions of brick render a table of exact 
 dimensions impracticable. 
 
 As an exponent, however, of the ranges of their dimensions, 
 the following averages are given: 
 
 Baltimore front "j 
 
 Wilmington front f- 8\ r in. X 4J in. X 2| in. 
 
 Washington front j 
 
 Croton front 8J in. X 4 in. X 2} in. 
 
 Maine ordinary 7J in'. X 3| ; in. X 2| in. 
 
 Milwaukee ordinary 8-J- in. X 4J in. X 2| in. 
 
 North River, N. Y 8 in. X 3 J- in. X 2} in. 
 
 English , 9 in. X 4J in. X 2J in. 
 
 The Standard Size as adopted by the National Brickmakers' Asso- 
 ciation and the National Traders and Builders' Association is for com- 
 mon brick 8} X 4 X 2f inches, and for face brick 8| X 4 J X 2 inches. 
 Re-pressed Brick weighs about 150 Ib. per cubic foot, common brick 
 125, inferior soft 100. Common bricks will average about 4J Ib. each. 
 Hollow Brick, used for interior walls and furring, are usually 
 of the following dimensions: 
 
 Single, 8 in. long, 3| in. wide, 2j in. thick. 
 Double, 8 " " 7i " " 4J " 
 Treble, 8 " " 7* " . " 7} " " 
 Roman Brick, 12 in. long, 4 to 4J in. wide, 1J in. thick. 
 
10 
 
 MASONRY CONSTRUCTION 
 
 TABLE 4. 
 Specific Gravity, Weight, and Resistance to Crushing of Brick, 
 
 Designation of brick. 
 
 Specific gravity. 
 
 Weight per cubic- 
 foot, pounds. 
 
 Resistance to 
 Crushing, pounds 
 per sq. in. 
 
 Best pressed. 
 
 2.4 
 
 150 
 
 5,000 to 14 973 
 
 Common hard; 
 Soft . 
 
 1.0 to 2.0 
 1 4 
 
 125 
 
 100 
 
 ."),()()() to <S,000 
 !.")() to (JOG 
 
 
 
 
 
 Fire-Brick are used wherever high temperatures are to he 
 resisted. They are made from fire-clay by processes very similar 
 to those adopted in making ordinary brick. Fire-clay is also used 
 in the manufacture of paving-blocks or pavers, especially in West- 
 ern Indiana; and many of the streets of our Western cities are laid 
 with fire-clay block, forming a smooth and durable roadway. 
 
 Fire-clay may be defined as native combinations of hyd rated 
 silicates of alumina, mechanically associated with silica and alumira 
 in various states of subdivision, and sufficiently free from silicates of 
 the alkalies and from iron and lime to resist vitrification at high tem- 
 peratures. The presence of oxide of iron is very injurious; and, as 
 a rule, the presence of G per cent justifies the rejection of the brick. 
 The presence of 3 per cent of combined lime, soda, potash, and mag- 
 nesia should be a cause for rejection. The sulphide of iron pyrites 
 is even worse than the substances first named. 
 
 A good fire-clay should contain from 52 to 80 per cent of silica 
 and 1 8 to 35 per cent of alumina and have a uniform texture, a some- 
 what greasy feel, and be free from any of the alkaline earths. 
 
 Good fire brick should be uniform in size, regular in shape, 
 homogeneous in texture and composition, strong, and infusible and 
 break with a uniform and regular fracture. 
 
 A properly burnt fire-brick is of a uniform color throughout its 
 mass. A dark central patch and concentric rings of various shades 
 of color are due mainly to the different states of oxidation of the 
 iron and partly to the presence of unconsumed carbonaceous mat- 
 ter, and indicates that the brick was burned too rapidly. 
 
 Fire-brick are made in various forms to suit the required work. 
 A straight brick measures 9 X 4J X 2-J inches and weighs about 7 Ib. 
 
MASONRY CONSTRUCTION 11 
 
 or 120 Ib. per cubic foot; specific gravity 1.93. One cubic foot of 
 wall requires 17 9-inch bricks; one cubic yard requires 460. One 
 ton of fire-clay should be sufficient to lay 3000 ordinary bricks. 
 English' fire-bricks measure 9 X 44 X 2J inches. 
 
 To secure the best results fire-brick should be laid in the same 
 clay from which they are manufactured. It should be used as a 
 thin paste, and not as mortar: the thinner the joint the better the 
 furnace wall. The brick should be dipped in water as they are 
 used, so that when laid they will not absorb the water from the 
 clay paste. They should then receive a thin coating of the prepared 
 fire-clay, and be carefully placed in position with as little of the fire- 
 clay as possible. 
 
 CEnENTINQ flATERIALS. 
 
 Composition. All the cementing materials employed in build- 
 ings are produced by the burning of natural or artificial mixtures 
 of limestone with clay or siliceous material. The active substances 
 in this process and the ones which are necessary for the production 
 of a cement, are the burned lime, the silica and the alumina, all of 
 which enter into chemical combination with one another under the 
 influence of a high temperature. 
 
 Classification. Owing to the varying composition of the raw 
 materials, which range from pure carbonate of lime to stones contain- 
 ing variable proportions of silica, alumina, magnesia, oxide of iron, 
 manganese, etc., and the different methods employed for burning, 
 the product possesses various properties which regulate its behavior 
 when treated with water, and render necessary certain precautions 
 in its manipulation and use, and furnishes a basis for division into 
 three classes; namely, common lime, hydraulic lime, and hydraulic 
 cements, the individual peculiarities of which will be taken up later. 
 
 Common lime is distinguished from hydraulic lime by its failure 
 to set or harden under water, a property which is possessed by hy- 
 draulic lime to a greater or less degree. 
 
 The limes are distinguished from the cements by the former 
 falling to pieces (slaking) on the application of water, while the 
 latter must be mechanically pulverized before they can be used. 
 
 The hydraulic cements are divided into two classes, namely, 
 natural and artificial. The first class includes all hydraulic substances 
 
12 MASONRY CONSTRUCTION 
 
 produced from natural mixtures of lime and clay, by a burning pro- 
 cess which has not been carried to the point of vitrification, and which 
 still contain more or less free lime. 
 
 The artificial cements are generally designated by the name 
 "Portland" and comprise all the cements produced from natural or 
 artificial mixtures of lime and clay, lime and furnace slag, etc., by a 
 burning process which is carried to the point of vitrification. 
 
 The hydraulic cements do not slake after calcination, differing 
 materially in this particular from the limes proper. They can be 
 formed into paste with water, without any sensible increase in volume, 
 and little, if any, production of heat, except in certain instances among 
 those varieties which contain the maximum amount of lime. They 
 do not shrink in hardening, like the mortar of rich lime, and can be 
 used with or without the addition of sand, although for the sake of 
 economy sand is combined with them. 
 
 All the limes and cements in practical use have one feature in 
 common, namely, the property of "setting" or "hardening" when 
 combined with a certain amount of water. The setting of a cement 
 is, in general, a complex process, partly chemical in its nature and 
 partly mechanical. Broadly stated, the chemical changes w r hich 
 occur may be said to afford opportunity for the mechanical changes 
 which result in hardening, rather than themselves to cause the harden- 
 ing. The chemical changes are, therefore, susceptible of wide varia- 
 tion without materially influencing the result. The crumbling which 
 calcined lime undergoes on being slaked is simply a result of the 
 mechanical disintegrating action of the evolved steam. In some 
 cements of which plaster of Paris may be taken as the type, water 
 simply combines with some constituent of the cement already present. 
 In others, of which Portland cement is the most important example, 
 certain chemical reactions must first take place. These reactions 
 give rise to substances which, as soon as formed, combine with water 
 and constitute the true cementitious material. The quantity of 
 water used should be regulated according to the kind of cement, since 
 every cement has a certain capacity for water. However, in practice 
 an excess of about 50 per cent must be used to aid manipulation. 
 
 The rapidity of setting (denominated activity) varies with the 
 character of the cement, and is influenced to a great extent by the 
 temperature, and also, but in less degree, by the purity of the water. 
 
:' HE 
 
 UNIVERSITY 
 
 OF 
 
 MASONRY CONSTRUCTION 13 
 
 Sea water hinders the setting of some cements, and some cements, 
 which are very hard in fresh water, only harden slightly in sea water 
 or even remain soft. Cements which require more than one-half 
 hour to set are called "slow-setting", all others "quick-setting". 
 As a rule the natural cements are quick- and the Portlands slow- 
 setting. None of the cements attain their maximum hardness until 
 some time has elapsed. For good Portland 15 days usually suffices 
 for complete setting, but the hardening process may continue for a 
 year or more. 
 
 The form and fineness of the cement particles are of great impor- 
 tance in the setting of the cement, and affect the cementing and 
 economic value. Coarse particles have no setting power and act as 
 an adulterant. In consequence of imperfect pulverization some 
 cements only develop three-fourths of their available activity, one- 
 fourth of the cement consisting of grains so coarse as to act merely 
 like so much sand. The best cement when separated from its fine 
 particles will not harden for months after contact with water, but sets 
 at once if previously finely ground. 
 
 In a mortar or concrete composed of a certain quantity of inert 
 material bound together by a cementing material it is evident that to 
 obtain a strong mortar or concrete it is essential that each piece of 
 aggregate shall be entirely surrounded by the cementing material, 
 so that no two pieces are in actual contact. Obviously, then, the 
 finer a cement the greater surface will a given weight cover, and the 
 more economy will there be in its use. The proper degree of fineness 
 is reached when it becomes cheaper to use more cement in propor- 
 tion to the aggregate than to pay the extra cost of additional grinding. 
 
 Use. Common lime is used almost exclusively in making 
 mortar for architectural masonry. Natural cement is used for 
 masonry where great ultimate strength is not as important as initial 
 strength and in masonry protected from the weather. Portland 
 cement is used for foundations and for all important engineering 
 structures requiring great strength or which are subject to shock; 
 also for all sub-aqueous construction. 
 
 LINES. 
 
 Rich Limes. The common fat or rich limes are those obtained 
 by calcining pure or very nearly pure carbonate of lime. In slaking 
 
14 MASONRY CONSTRUCTION 
 
 they augment to from two to three and a half times that of the original 
 mass. They will not harden under water, or even in damp places 
 excluded from contact with the air. In the air they harden by the 
 gradual formation of carbonate of lime, due to the absorption of car- 
 bonic acid gas. 
 
 The pastes of fat lime shrink in hardening to such a degree that 
 they cannot be employed for mortar without a large dose of sand. 
 
 Poor Limes. The poor or meagre limes generally contain 
 silica, alumina, magnesia, oxide of iron, sometimes oxide of man- 
 ganese, and in some cases traces of the alkalies, in relative propor- 
 tions which vary considerably in different localities. In slaking they 
 proceed sluggishly, as compared with the rich limes the action only 
 commences after an interval of from a few minutes to more than an 
 hour after they are wetted; less water is required for the process, and 
 it is attended with less heat and increase of volume than in the case 
 of fat limes. 
 
 Hydraulic Limes. The hydraulic limes, including the three 
 subdivisions, viz., slightly hydraulic, hydraulic, and eminently hydra n- 
 lic, are those containing after calcination sufficient of such foreign 
 constituents as combine chemically with lime and water to confer 
 an appreciable power of setting or hardening under water without 
 the access of air. They slake still slower than the meagre limes, and 
 with but a small augmentation of volume, rarely exceeding 30 per 
 cent of the original bulk. 
 
 Lime is shipped either in bulk or in barrels. If in bulk, it is 
 impossible to preserve it for any considerable length of time. A 
 barrel of lime usually weighs about 230 Ib. net, and will make about 
 three tenths of a cubic yard of stiff paste. A bushel weighs 75 Ib. 
 
 NATURAL CEflENT. 
 
 Rosendale or natural cements are produced by burning in draw- 
 kilns at a heat just sufficient in intensity and duration to expel the 
 carbonic acid from argillaceous or silicious limestones containing 
 less than 77 per cent of carbonate of lime, or argillo-magnesian lime- 
 stone containing less than 77 per cent of both carbonates, and then 
 grinding the calcined product to a fine powder between millstones. 
 
 Characteristics. The natural cements have a porous, globu- 
 lar texture. They do not heat up nor swell sensibly when mixed with 
 
MASONRY CONSTRUCTION 15 
 
 water. They set quickly in air, but harden slowly under water, 
 without shrinking, and attain great strength with ' well-developed 
 adhesive force. 
 
 S eft ing . A pat made with the minimum amount of water should 
 set in about 30 minutes. 
 
 Fineness. At least 93 per cent must pass through a No. 50 sieve. 
 
 Weight. Varies from 49 to 56 pounds per cubic foot. 
 
 Specific Gravity about 2.70. 
 
 Tensile Strength. Neat cement, one day, from 40 to 80 pounds. 
 Seven days, from 60 to 100 pounds. One year, from 300 to 400 
 pounds. 
 
 PORTLAND CEHENT. 
 
 Portland Cement is produced by burning, with a heat of suf- 
 ficient intensity and duration to induce incipient vitrification, certain 
 argillaceous limestones, or calcareous clays, or an artificial mixture of 
 carbonate of lime and clay, and then reducing the burnt material to 
 powder by grinding. Fully 95 per cent of the Portland cement pro- 
 duced is artificial. The name is derived from the resemblance which 
 hardened mortar made of it bears to a stone found in the isle of Port- 
 land, off the south coast of England. 
 
 The quality of Portland cement depends upon the quality of the 
 raw materials, their proportion in the mixture, the degree to which 
 the mixture is burnt, the fineness to which it is ground, and the con- 
 stant and scientific supervision of all the details of manufacture. 
 
 Characteristics. The color should be a dull bluish or green- 
 ish gray, caused by the dark ferruginous lime and the intensely green 
 manganese salts. Any variation from this color indicates the pres- 
 ence of some impurity; blue indicates an excess of lime; dark green, 
 a large percentage of iron; brown, an excess of clay; a yellowish shade 
 indicates an underburned material. 
 
 Fineness. It should have a clear, almost floury feel in the hand; 
 a gritty feel denotes coarse grinding. 
 
 Specific Gravity is between 3 and 3.05. As a rule the strength 
 of Portland cement increases with its specific gravity. 
 
 Tensile Strength. When moulded neat into a briquette and 
 placed in water for seven days it should be capable of resisting a ten- 
 sile strain of from 300 to 500 pounds per square inch. 
 
16 MASONRY CONSTRUCTION 
 
 Setting. A pat made with the minimum amount of water should 
 set in not less than three hours, nor take more than six hours. 
 
 Expansion and Contraction. Pats left in the air or placed in 
 water should during or after setting show neither expansion nor con- 
 traction, either by the appearance of cracks or change of form. 
 
 A cement that possesses the foregoing properties may be con- 
 sidered a fair sample of Portland cement and would be suitable for 
 any class of work. 
 
 Overtimed Cement is likely to gain strength very rapidly in the 
 beginning and later to lose its strength, or if the percentage of free 
 lime be sufficient it will ultimately disintegrate. 
 
 Blowing or Swelling of Portland cement is caused by too much 
 lime or insufficient burning. It also takes place when the cement is 
 very fresh and has not had time to cool. 
 
 Adulteration. Portland cement is adulterated with slag cement 
 and slaked lime. This adulteration may be distinguished by the 
 light specific gravity of the cement, and by the color, which is of a 
 mauve tint in powder, while the inside of a water-pat when broken 
 is deep indigo. Gypsum or sulphate of lime is also used as an 
 adulterant. 
 
 TESTING CEHENTS. 
 
 The quality or constructive value of a cement is generally ascer- 
 tained by submitting a sample of the particular cement to a series of 
 tests. The properties usually examined are the color, weight, activity, 
 soundness, fineness and tensile strength. Chemical analysis is some- 
 times made, and specific gravity test s substituted for that of weight. 
 Tests of compression and adhesion are also sometimes added. As 
 these tests cannot be made upon the site of the work, it is usual to 
 sample each lot of cement as it is delivered and send the samples to a 
 testing laboratory. 
 
 Sampling Cement. The cement is sampled by taking a small 
 quantity (1 to 2 Ib.) from the center of the package. The number 
 of packages sampled in any given lot of cement will depend upon 
 the character of the work, and varies from every package to 1 in ."> 
 or 1 in 10. When the cement is brought in barrels the salnple is 
 obtained by boring with an auger either in the head or center of the 
 barrel, drawing out a sample, then closing the hole with a piece of 
 
MASONRY CONSTRUCTION 17 
 
 tin firmly tacked over it. For drawing out the sample a brass tube 
 sufficiently long to reach the bottom of the barrel is used. This is 
 thrust into the barrel, turned around, pulled out, and the core of 
 cement knocked out into the sample-can, which is usually a tin box 
 with a tightly fitting cover. 
 
 Each sample should be labelled, stating the number of the sam- 
 ple, the number of bags or barrels it represents, the brand of the 
 cement, the purpose for which it is to be used, the date of delivery, 
 and date of sampling. 
 
 FORM OF LABEL. 
 
 Sample No ............ . 
 
 No. of Barrels .......... 
 
 Brand ....................... 
 
 To be used 
 
 Delivered .............. . . Sampled. 
 
 The sample should be sent at once to the testing office, and none 
 of the cement should be used until the report of the tests is received. 
 
 After the. report of the tests is received the rejected packages 
 should be conspicuously marked with a "C" and should be removed 
 without delay; otherwise they are liable to be used. 
 
 Color. The color of a cement indicates but little, since it is 
 chiefly due to oxides of iron and manganese, which in no way affect 
 the cementitious value; but for any given kind variations in shade 
 may indicate differences in the character of the rock or in the degree 
 of burning. The natural cements may have almost any color from 
 the very light straw colored "Utica" through the brown "Louisville", 
 to chocolate "Rosendale". The artificial Portlands are usually a 
 grayish blue or green, but never chocolate colored. 
 
 Weight. For any particular cement the weight varies with the 
 degree of heat in burning, the degree of fineness in grinding, and the 
 density of packing. The finer a cement is ground the more bulky 
 it becomes, and consequently the less it weighs. Hence light weight 
 may be caused by laudable fine grinding or by objectionable under- 
 burning. Other things being the same, the harder-burned varieties 
 are the heavier. 
 
18 MASONRY CONSTRUCTION 
 
 The weight per unit of volume is usually determined by sifting 
 the cement into a measure as lightly as possible, and striking the top 
 level with a straight edge. In careful work the height of fall should 
 be recorded. Since the cement absorbs moisture, the sample must 
 be taken from the interior of the package. The weight per cubic foot 
 is neither exactly constant, nor can it be determined precisely. The 
 approximate weight of cement per cubic foot is as follows: 
 
 Portland, English and German 77 to 90 Ib. 
 
 fine-ground French 09 " 
 
 American... . 92 " 95 " 
 
 Rosendale 49 " 50 " 
 
 Roman 54 " 
 
 A bushel contains 1.244 cubic feet. The weight of a bushel can 
 be obtained sufficiently close by adding 25 per cent to the weight per 
 cubic foot. 
 
 Fineness. The cementing and economic value of a cement is 
 affected by the degree of fineness to which it is ground. Coarse 
 particles in a cement have no setting power and act as an adulterant. 
 
 The fineness of a cement is determined by measuring the per- 
 centage which will not pass through sieves of a certain number of 
 meshes per square inch. Three sieves are generally used, viz.: 
 
 No. 50, 2,500 meshes per square inch. 
 No. 74, 5,476 
 No. 100, 10,000 
 
 Activity denotes the speed with which a cement begins to set. 
 Cements differ widely in their rate and manner of sdtiny. Some 
 occupy but a few minutes in the operation, and others require several. 
 Some begin setting immediately and take considerable time to com- 
 plete the set, while others stand for a considerable time with no ap- 
 parent action and then set very quickly. The point at which the set 
 is supposed to begin is when the stiffening of the mass firxt becomes 
 perceptible, and the end of the set is when cohesion extends through 
 the mass sufficiently to offer such resistance to any change of form 
 as to cause rupture before any deformation can take place. 
 
 Test of Activity. To test the activity mix the cement with 
 25 to 30 per cent of its weight of clean water, having a temperature 
 of between 05 F. and 70 F., to a stiff plastic mortar, and make one 
 
MASONRY CONSTRUCTION 
 
 19 
 
 or two rakes or pats 2 or 3 inches in diameter and about J inch in 
 thickness. As soon as the cakes are prepared, immerse in water at 
 05 F., and note the time required for them to set hard enough to bear 
 respectively a -^-inch wire loaded to weigh J pound, and a ^-inch 
 vvire loaded to weigh 1 pound. When the cement bears the light 
 weight, it is said to have begun to set; when it bears the heavy weight, 
 it is said to have entirely set. The apparatus employed for this test 
 is shown in Fig. 1, and is called "Vicat's Needle apparatus". 
 
 Fig. 1. Vicat's Needle Apparatus. 
 
 Quick and Slow Setting. The aluminous natural cements 
 are commonly " quick-setting/' though not always so, as those con- 
 taining a considerable percentage of sulphuric acid may set quite 
 slowly. The magnesian and Portland varieties may be either " quick " 
 or "slow". Specimens of either variety may be had that will set at 
 any rate^ from the slowest to the most rapid, and no distinction can 
 be drawn between the various classes in this regard. 
 
 Water containing sulphate of lime in solution retards the setting, 
 This fact has been made use of in the adulteration of cement, pow- 
 dered gypsum being mixed with it to make it slow-setting, greatly to 
 the injury of the material. 
 
20 MASONRY CONSTRUCTION 
 
 The temperature of the water used affects tne time required for 
 setting; the higher the temperature, within certain limits, the more 
 rapid the set. Many cements which require several hours to set when 
 mixed with water at a temperature of 40 F. will set in a few minutes 
 if the temperature of the water be increased to 80 F. Below a cer- 
 tain inferior limit, ordinarily from 30 to 40 F., the cement will not 
 set, while at a certain upper limit, in many cements between 100 and 
 140 F., a change is suddenly made from a very rapid to a very slow 
 rate, which then continually decreases as the temperature increases, 
 until practically the cement will not set. 
 
 The quick-setting cements usually set so that experimental sam- 
 ples can be handled within 5 to 30 minutes after mixing. The slow- 
 setting cements require from 1 to 8 hours. Freshly ground cements 
 set quicker than older ones. 
 
 Soundness denotes the property of not expanding or contracting 
 or cracking or checking in setting. These effects may be due to free 
 lime, free magnesia, or to unknown causes. Testing soundness is, 
 therefore, determining whether the cement contains any active im- 
 purity. An inert adulteration or impurity affects only its economic 
 value; but an active impurity affects also its strength and durability. 
 
 For the purpose of determining the amount of contraction or 
 expansion the "Bauschinger" apparatus, Fig. 2, is used. A mould 
 is used in which the test bars of cement are formed. 
 
 Tests of Soundness. The soundness of a cement may be 
 determined by cold tests, so-called, the cement being at ordinary 
 temperature; or by accelerated or hot tests. 
 
 To make the cold tests, prepare small cakes or pats of neat 
 cement, 3 or 4 inches in diameter and about one-half inch thick 
 at the center, tapering to a thin edge. Place the samples upon a piece, 
 of glass and cover with a damp cloth for a period of 24 hours and then 
 immerse glass and all in water for a period of 28 days if possibly, 
 keeping watch from day to day to see if the samples show any cracks 
 or signs of distortion. 
 
 The first indication of inferior quality is the loosening of the pat 
 from the glass, which usually takes place in one or two days. Good 
 cement will remain firmly attached to the glass for two weeks at least, 
 
 The ordinary tests, extending over a proper interval, often fail 
 to detect unsoundness, and circumstances may render the ordinary 
 
MASONRY CONSTRUCTION 
 
 21 
 
 tests impossible from lack of time. Under such circumstances resort 
 must be had to accelerated tests, which may be made in several ways. 
 Warm=Water Test. Prepare the sample as before, and after 
 allowing it to set, immerse in water maintained at a temperature of 
 from 100 to 115 F. If the specimen remains firmly attached to the 
 glass and shows no cracks, it is probably sound. 
 
 Fig. 2. Bauschinger's Apparatus. 
 
 The hot-water test is similar to the last, but the water is main- 
 tained at a temperature of from 195 to 200 F. 
 
 The boiling test consists in immersing the specimen in cold water 
 immediately after mixing and gradually raising the temperature of 
 the water to the boiling point, continuing the boiling for three hours. 
 
 For an emergency test, the specimen may be prepared as before, 
 and after setting may be held under a steam cock of a boiler and live 
 steam discharged upon it. 
 
 The results of accelerated tests must not be accepted too literally, 
 but should be interpreted in the light of judgment and experience. 
 
22 MASONRY CONSTRUCTION 
 
 The cracking or contortion of the specimen (sometimes called 
 "blowing"), is due to the hydration and consequent expansion of the 
 lime or magnesia. If the effect is due to lime, the cement can be im- 
 proved by exposure to the air, thus allowing the free lime to slake. 
 This treatment is called "cooling the cement". The presence of 
 uncombined magnesia is more harmful than that of lime. 
 
 Some idea of the quality of a cement may be gained by exposing 
 to the air a small cake of neat cement mortar and observing its color. 
 "A good Portland cement should be uniform bluish gray throughout, 
 yellowish blotches indicate poor cement". 
 
 Tests of soundness should not only be carefully conducted, but 
 should extend over considerable time. Occasionally cement is found 
 which seems to meet the usual tests for soundness, strength, etc., and 
 yet after considerable time loses all coherence and falls to pieces. 
 
 Strength. The strength is usually determined by submitting 
 a specimen of known cross-section (generally one square inch) to a 
 tensile strain. The reason for adopting a tensile test is that since 
 even the weakest cement cannot be crushed, in ordinary practice, 
 by direct compression, and since cement is not used in places where 
 cross strain is brought to bear upon it, torsion being out of the ques- 
 tion, the only valuable results can be derived from tests for tensile 
 strength. In case of a cracking wall the strain is that of tension due 
 to the difference of the direction of the strain caused by the sinking 
 of one part of the wall. 
 
 In comparing different brands of cement great care must be 
 exercised to see that the same kind and quality of sand is used in 
 each case, as difference in the sand will cause difference in the results. 
 To obviate this a standard sand is generally used. This consists of 
 crushed quartz of such a degree of fineness that it will all pass a No. 
 20 sieve (400 meshes to the square inch; wire No. 28 Stubbs' gauge) 
 and be caught on a No. 30 sieve (900 meshes to the square inch; wire 
 No. 31 Stubbs' gauge). 
 
 Valuable and probably as reliable comparative tests can be made 
 with the sand which is to be used for making the mortar in the pro- 
 posed work. Specimens of neat cement are also used for testing, 
 they can be handled sooner and will show less variation than speci- 
 mens composed of cement and sand. 
 
MASONRY CONSTRUCTION 
 
 23 
 
 The cement is prepared for testing by being formed into a stiff 
 paste by the addition of just sufficient water for this purpose. When 
 sand is to be added, the exact proportions should be carefully deter- 
 mined by weight and thoroughly and intimately mixed with the cement 
 in a dry state before the water is added; and, so far as possible, all 
 the water that is necessary to produce the desired consistency should 
 be added at once and thereafter the manipulation with the spatula 
 or trowel should be rapid and thorough. The mortar so obtained 
 is filled into a mould of the form and dimensions shown in Fig. 3. 
 These moulds are usually of iron or brass. Wooden moulds, if 
 well oiled to prevent their absorbing water, answer the purpose well 
 for temporary use, but speedily become unfit for accurate work. In 
 filling the mould care must be exercised to complete the filling before 
 incipient setting begins. 
 
 The moulds while being 
 charged and manipulated, 
 should be laid on glass, slate, 
 or some other non-absorbent 
 material. The specimen, now 
 called the "briquette", should 
 be removed from the mould 
 as soon as it is hard enough 
 to stand it, without breaking. Fig. 3. Briquette Mould. 
 
 The briquettes are then im- 
 mersed in water, where they should remain constantly covered until 
 tested. If they are exposed to the air, the water may be carried 
 away by evaporation and leave the mortar a pulverant mass. Also, 
 since the mortar does not ordinarily set as rapidly under water as 
 in the air (owing to the difference in temperature), it is necessary for- 
 accurate work to note the time of immersion, and also to break the 
 briquette as soon as it is taken from the water. Cement ordinarily 
 attains a greater strength when allowed to set under water, but attains 
 it more slowly. 
 
 Age of Briquette for Testing. It is customary to break part 
 of the briquettes at the end of seven days, and the remainder at 
 the end of twenty-eight days. As it is sometimes impracticable to 
 wait twenty-eight days, tests are often made at the end of one and 
 seven days, respectively. The ultimate strength of the cement is 
 
MASONRY CONSTRUCTION 
 
 judged by the increase in strength between the two dates. A mini- 
 mum strength for the two dates is usually specified. 
 
 Testing the Briquettes. When taken out of the water the 
 briquettes are subjected to a tensile strain until rupture takes place in 
 a suitably devised machine. There are several machines on the mar- 
 ket for this purpose. Fig. 4 represents one which is extensively used. 
 
 To make a test, hang the cup F on the end of the beam Z), as 
 shown in the illustration. See that the poise R is at the zero mark, 
 
 Fig. 4. Cement Testing Machine. 
 
 and balance the beam by turning the ball L. Fill the hopper B with 
 fine shot, place the specimen in the clamps N N, and adjust the 
 hand wheel P so that the graduated beam D will rise nearly to the 
 stop K. 
 
 Open the automatic valve J so as to allow the shot to run slowly 
 into the cup F. Stand back and leave the machine to make the test. 
 
 When the specimen breaks, the graduated beam D drops and 
 closes the valve J, remove the cup with the shot in it, and hang the 
 counterpoise weight G in its place. 
 
MASONRY CONSTRUCTION 
 
 25 
 
 Hang the cup F on the hook under the large ball E, and proceed 
 to weigh the shot in the regular way, using the poise R on the gradu- 
 ated beam D, and the weights // on the counterpoise weight G. 
 The result will show the number of pounds required to break the 
 specimen. 
 
 TABLE 5. 
 Tensile Strength of Cement Mortar. 
 
 Age of mortar when tested. 
 
 Average tensile strength in pounds 
 per square inch. 
 
 Portland. 
 
 Rosendale. 
 
 CLEAR CEMENT. 
 One hour, or until set, in air, the 
 remainder of the time in water: 
 1 day 
 
 Min. 
 100 
 
 250 
 350 
 450 
 
 Max. 
 
 140 
 
 550 
 700 
 
 800 
 
 Min. 
 
 40 
 
 60 
 100 
 300 
 
 30 
 50 
 200 
 
 Max. 
 
 80 
 
 100 
 150 
 400 
 
 50 
 
 -80 
 300 
 
 One day in air, the remainder of 
 the time in water: 
 1 week 
 
 4 weeks.. 
 
 1 year 
 
 1 PART CEMENT TO 1 PART SAND. 
 One day in air, the remainder of 
 the time in water: 
 1 week 
 
 4 weeks 
 
 
 
 1 year . 
 
 
 
 1 PART CEMENT TO 3 PARTS SAND. 
 One day in air, the remainder of 
 the time in water: 
 1 week i ....*... 
 
 80 
 100 
 200 
 
 125 
 200 
 350 
 
 4 weeks 
 
 
 
 1 year . 
 
 
 
 
 
 
 CEflENTS flEflORANDA. 
 
 Cement is shipped in barrels or in cotton or paper bags. 
 The usual dimensions of a barrel are: length 2 ft. 4 in., middle 
 diameter 1 ft. 4^ in., end diameter 1 ft. 3^ in. 
 The bags hold 50, 100, or 200 pounds. 
 
26 MASONRY CONSTRUCTION 
 
 A barrel weighs about as follows : 
 
 Rosendale, N.Y. ................. ...... 300 11). net 
 
 Rosendale, Western ............ .......... 205 
 
 Portland .............................. 375 " 
 
 A barrel of Rosendale cemejit contains about 3.40 cubic feet 
 and will make from 3.70 to 3.75 cubic feet of stiff paste, or 79 to 
 83 pounds will make about one cubic foot 'of paste. A barrel of 
 Rosendale cement (300 Ib.) and two barrels of sand (7J cubic^feet) 
 mixed with about half a barrel of water will make about 8 cubic feet 
 of mortar, sufficient for 
 
 192 square feet of mortar-joint J inch thick. 
 
 384 " } " 
 
 768 " " " " " 
 
 A barrel of Portland cement contains ibout 3.25 to 3.35 cubic 
 feet 100 pounds will make about one cubic foot of stiff paste. 
 
 A barrel of cement measured loosely increases considerably in 
 bulk. The following results were obtained by measuring in quan- 
 tities of two cubic feet : 
 
 1 bbl. Norton's Rosendale gave .......... 4.37 cu. ft. 
 
 Anchor Portland gave ............ 3 . 65 
 
 " Sphinx Portland gave ............ 3.71 " 
 
 " Buckeye Portland gave.. . . ........ 4.25 " 
 
 Preservation of Cements. Cements require to be stored in 
 a dry place protected from the weather; the packages should 
 not be placed directly on the ground, but on boards raised a few 
 inches from it. If necessary to stack it out of doors a platform of 
 planks should first be made and the pile covered with canvas. Port- 
 land cement exposed to the atmosphere will absorb moisture until 
 it is practically ruined. The absorption of moisture by the natural 
 cements will cause the development of carbonate of lime, which will 
 interfere with the subsequent hydration. 
 
 niSCELLANEOUS CEflENTS. 
 
 Slag Cements are those formed by an admixture of slaked lime 
 with ground blast-furnace slag. The slag used has approximately 
 the composition of an hydraulic cement, being composed mainly of 
 silica and alumina, and lacking a proper proportion of lime to render 
 
MASONRY CONSTRUCTION 27 
 
 it active as a cement. In preparing the cement the slag upon coming 
 from the furnace is plunged into water and reduced to a spongy form 
 from which it may be readily ground. This is dried and ground to a 
 fine powder. The powdered slag and slaked lime are then mixed 
 in proper proportions and ground together, so as to very thoroughly 
 distribute them through the mixture. It is of the first importance 
 in a slag cement that the slag be very finely ground, and that the 
 ingredients be very uniformly and intimately incorporated. 
 
 Both the composition and methods of manufacture of slag 
 cements vary considerably in different places. They usually con- 
 tain a higher percentage of alumina than Portland cements, and 
 the materials are in a different state of combination, as, being mixed 
 after the burning, the silicates and aluminates of lime formed during 
 the burning of Portland cement cannot exist in slag cement. 
 
 The tests for slag cement are that briquettes made of one part 
 of cement and three parts of sand by weight shall stand a tensile 
 strain of 140 pounds per square inch (one day in air and six in water), 
 and must show continually increasing strength after seven days, one 
 month, etc. At least 90 per cent must pass a sieve containing 40,000 
 meshes to the square inch, and must stand the boiling test. 
 
 Pozzuolanas are cements made by a mixture of volcanic ashes 
 with lime, although the name is sometimes applied to mixed cements 
 in general. The use of pozzuolana in Europe dates back to the 
 time of the Romans. 
 
 Roman Cement is a natural cement manufactured from the 
 septaria nodules of the London Clay formation; it is quick-setting, 
 but deteriorates with age and exposure to the air. 
 
 HORTAR. 
 
 Ordinary flortar is composed of lime and sand mixed into 
 a paste with water. When cement is substituted for the lime, the 
 mixture is called cement mortar. 
 
 Uses. The use of mortar in masonry is to bind together the 
 bricks or stones, to 'afford a bed which prevents their inequalities 
 from bearing upon one another and thus to cause an equal distribu- 
 tion of pressure over the bed. It also fills up the spaces between 
 the bricks or stones and renders the wall weathe" tight. It is also 
 used in concrete as a matrix for broken stones or other bodies to be 
 
28 MASONRY CONSTRUCTION 
 
 amalgamated into one solid mass; and for plastering and other 
 purposes. 
 
 The quality of mortar depends upon the character of the materials 
 used in its manufacture, their treatment, proportions, and method 
 of mixing. 
 
 Proportions. The proportion of cement to sand depends upon 
 the nature of the work and the necessity for the development of 
 strength or imperviousness. The relative quantities of sand and 
 cement should also depend upon the nature of the sand; fine sand 
 requires more cement than coarse. Usual proportions are: 
 
 Lime mortar, 1 part of lime to 4 parts of sand. 
 
 Natural cement mortar, 1 part cement to 2 or 3 parts of sand. 
 
 Portland cement mortar, 1 part cement to 2, 3, or 4 parts of sand, 
 according to the character of the work. 
 
 Sand for flortar. The sand used must be clean, that is, free 
 from clay, loam, mud, or organic matter; sharp, that is, the grains 
 must be angular and not rounded as those from the beds of rivers 
 and the seashore; coarse, that is, it must be large-grained, but not 
 too uniform in size. 
 
 The best sand is that in which the grains are of different sizes; 
 the more uneven the sizes the smaller will be the amount of voids, 
 and hence the less cement required. 
 
 The cleanness of sand may be tested by rubbing a little of the 
 dry sand in the palrn of the hand, and after throwing it out noticing 
 the amount of dust left on the hand. The cleanness may also be 
 judged by pressing the sand between the fingers while it is damp; 
 if the sand is clean it will not stick together, but will immediately 
 fall apart when the pressure is removed. 
 
 The sharpness of sand can be determined approximately by 
 rubbing a few grains in the hand or by crushing it near the ear and 
 noting if a grating sound is produced; but an examination through 
 a small lens is better. 
 
 To determine the presence of Salt and Clay. Shake up a small 
 portion of the sand with pure distilled water in a perfectly clean 
 stoppered bottle, and allow the sand to settle; add a few drops of 
 pure nitric acid and then add a few drops of solution of nitrate of 
 silver. A white precipitate indicates a tolerable amount of salt; a 
 faint cloudiness may be disregarded. 
 
MASONRY CONSTRUCTION 29 
 
 The presence of clay may be ascertained by agitating a small 
 quantity of the sand in a glass of clear water and allowing it to stand 
 for a few hours to settle; the sand and clay will separate into two 
 well-defined layers. 
 
 Screening. Sand is prepared for use by screening to remove 
 the pebbles and coarser grains. The fineness of the meshes of the 
 screen depends upon the kind of work in which the sand is to be used. 
 
 Washing. Sand containing loam or earthy matters is cleansed 
 by washing with water, either in a machine specially designed for the 
 purpose and called a sand-washer, or by agitating with water in tubs 
 or boxes provided with holes to permit the dirty water to flow away. 
 
 Water for flortar. The water employed for mortar should 
 be fresh and clean, free from mud and vegetable matter. Salt water 
 may be used, but with some natural cements it may retard the setting, 
 the chloride and sulphate of magnesia being the principal retarding 
 elements. Less sea-water than fresh will be required to produce a 
 given consistency. 
 
 Quantity. The quantity of water to be used in mixing mortar 
 can be determined only by experiment in each case. It depends 
 upon the nature of the cement, upon that of the sand and of the water, 
 and upon the proportions of sand to cement, and upon the purpose 
 for which the mortar is to be used. 
 
 Fine sand requires more water than coarse to give the same con- 
 sistency. Dry sand will take more water than that which is moist, 
 and sand composed of porous material more than that which is hard. 
 As the proportion of sand to cement is increased the proportion of 
 water to cement should also increase, but in a much less ratio. 
 
 The amount of water to be used is such that the mortar when 
 thoroughly mixed shall have a plastic consistency suitable for the 
 purpose for which it is to be used. 
 
 The addition of water, little by little, or from a hose, should 
 not be allowed. 
 
 Cement flortar. In mixing cement mortar the cement and 
 sand are first thoroughly mixed dry, the water then added, and the 
 whole worked to a uniformly plastic condition. 
 
 The quality of the mortar depends largely upon the thoroughness 
 of the mixing, the great object of which is to so thoroughly incorporate 
 the ingredients that no two grains of sand shall lie together without 
 
30 MASONRY CONSTRUCTION 
 
 an intervening layer or film of cement. To accomplish this the 
 cement must be uniformly distributed through the sand during the 
 dry mixing. 
 
 The mixers usually fail to thoroughly intermix the dry cement 
 and sand, and to lighten the labor of the wet mixing they will give 
 an overdose of water. 
 
 Packed cement when measured loose increases in volume to 
 such an extent that a nominal 1 to 3 mortar is easily changed to an 
 actual 1 to 4. The specifications should prescribe the manner in 
 which the materials are to be measured, i.e., packed or loose. 
 
 The quantity of sand will also vary according to whether it is 
 measured in a wet or dry condition, packed or loose. On work of 
 sufficient importance to justify some sacrifice of convenience the 
 sand and cement should be proportioned by weight instead of by 
 volume. 
 
 In mixing by hand a platform or box should be used; the sand 
 and cement should be spread in layers with a layer of sand at the 
 bottom, then turned and mixed with shovels until a thorough incor- 
 poration is effected. The dry mixture should then be spread out, 
 a bowl-like depression formed in the center and all the water required 
 poured into it. The dry material from the outside of the basin should 
 be thrown in until the water is taken up and then worked into a 
 plastic condition, or the dry mixture may be shovelled to one end of 
 the box and the water poured into the other end. The mixture of 
 sand and cement is then drawn down with a hoe, small quantities 
 at a time, and mixed with the water until enough has been added 
 to make a good stiff mortar. 
 
 In order to secure proper manipulation of the materials on the 
 part of the workmen it is usual to require that the whole mass shall 
 be turned over a certain number of times with the shovels, both dry 
 and wet. 
 
 The mixing wet with the shovels must be performed quickly 
 and energetically. The paste thus made should be vigorously worked 
 with a hoe for several minutes to insure an even mixture. The 
 mortar should then leave the hoe clean when drawn out of it, and 
 very little should stick to the steel. 
 
 A large quantity of cement and sand should not be mixed dry 
 and left to stand a considerable time before using, as the moisture 
 
MASONRY CONSTRUCTION 31 
 
 in the sand will to some extent act upon the cement, causing a partial 
 setting. 
 
 Upon large works mechanical mixers are frequently employed 
 with the. advantage of at once lessening the labor of manipulating 
 the material and insuring good work. 
 
 Retempering flortar. Masons very frequently mix mortar in 
 considerable quantities, and if the mass becomes stiffened before 
 being used, by the setting of the cement, add water and work it again 
 to a soft or plastic condition. After this second tempering the cement 
 is much less active than at first, and will remain for a longer time in 
 a workable condition. 
 
 This practice is condemned by engineers, and is not usually 
 allowed in good engineering construction. Only sufficient quantity 
 of mortar should be mixed at once as may be used before the cement 
 takes the initial set. Reject all mortar that has set before being 
 placed in the w^ork. 
 
 Freezing of flortar. It does not appear that common lime 
 mortar is seriously injured by freezing, provided it remains frozen 
 until it has fully set. The freezing retards, but does not entirely 
 suspend the setting. Alternate freezing and thawing materially 
 damages the strength and adhesion of lime mortar. 
 
 Although the strength of the mortar is not decreased by freezing, 
 it is not always permissible to lay masonry during freezing weather; 
 for example, if, in a thin wall, the mortar freezes before setting and 
 afterwards thaws on one side only, the wall may settle injuriously. 
 
 Mortar composed of one part Portland cement and three parts 
 sand is entirely uninjured by freezing and thawing. 
 
 Mortar made of cements of the Rosendale type, in any propor- 
 tion, is entirely ruined by freezing and thawing. 
 
 Mortar made of overclayed cement (which condition is indicated 
 by its quicker setting), of either the Portland or Rosendale type, 
 will not withstand the action of frost as well as one containing less 
 clay, for .since the clay absorbs an excess of water, it gives an increased 
 effect to the action of frost. 
 
 In making cement mortar during freezing weather it is cus- 
 tomary to add salt or brine to the water with which it is mixed. The 
 ordinary rule is: Dissolve 1 pound of salt in 18 gallons of water 
 
 QF THE 
 
 UNIVERSITY 
 
 OF 
 
32 
 
 MASONRY CONSTRUCTION 
 
 when the temperature is at 32 F., and add 1 ounce of salt for each 
 degree of lower temperature. 
 
 The use of salt, and more especially of sea-water, in mortar is 
 objectionable in exposed walls, since the accompanying salts usually 
 produce efflorescence. 
 
 The practice of adding hot water to lime mortar during freezing 
 weather is undesirable. When the very best results are sought the 
 brick or stone should be warmed enough to thaw off any ice upon 
 the surface is sufficient before being laid. They may be warmed 
 either by laying them on a furnace, or by suspending them over a 
 slow fire, or by wetting with hot water. 
 
 TABLE 6. 
 
 Amount of Cement and Sand Required for One Cubic Yard of 
 
 flortar. 
 
 Composition of mortar by 
 volumes. 
 
 Cement.* 
 Number of barrels. 
 
 Cement. 
 
 Sand. 
 
 Portland or 
 Ulster County 
 Rosendale. 
 
 
 
 Western 
 Koseudale. 
 
 
 
 
 7.14 
 
 6.43 
 
 
 1 
 
 4.16 
 
 3.71 
 
 
 2 
 
 2.85 
 
 2.57 
 
 
 3 
 
 2.00 
 
 1.80 
 
 
 4 
 
 1.70 
 
 1.53 
 
 
 5 
 
 1.25 
 
 1.13 
 
 1 
 
 6 
 
 1.18 
 
 1.06 
 
 
 
 Cement. Number of Pounds.t 
 
 1 
 
 
 
 2675 
 
 2140 
 
 1 
 
 1 
 
 1440 
 
 1150 
 
 1 
 
 2 
 
 900 
 
 720 
 
 1 
 
 3 
 
 675 
 
 540 
 
 1 
 
 4 
 
 525 
 
 420 
 
 1 
 
 5 
 
 425 
 
 340 
 
 1 
 
 
 
 355 
 
 285 
 
 Sand. 
 cubic. 1 yards 
 
 0.00 
 0.58 
 0.80 
 
 0.90 
 0.95 
 0.97 
 0.98 
 
 0.00 
 0,67 
 0.84 
 0.94 
 0.9S 
 0*99 
 1.00 
 
 * Packed cement and loose sand. 
 t Loose cement and loose sand. 
 
MASONRY CONSTRUCTION 33 
 
 CONCRETE. 
 
 Concrete is a species of artificial stone composed of (1) the 
 matrix, which may be either lime or cement mortar, usually the latter, 
 and (2) the aggregate, which may be any hard material, as gravel, 
 shingle, broken stone, shells, brick, slag, etc. 
 
 The aggregate should be of different sizes, so that the smaller 
 shall fit into the voids between the larger. This requires less mortar 
 and with good aggregate gives a stronger concrete. Broken stone 
 is the most common aggregate. 
 
 Gravel and shingle should be screened to remove the larger-sized 
 pebbles, dirt, and vegetable matter, and should be washed if they 
 contain silt or loam. The broken stone if mixed with dust or dirt 
 must be washed before .use. 
 
 Strength of Concrete. The resistance of concrete to crush- 
 ing ranges from about 600 to 1400 pounds per sq. in. It depends 
 upon the kind and amount of cement and upon the kind, size, and 
 strength of the aggregate. The transverse strength ranges between 
 50 and 400 pounds. 
 
 Weight of Concrete. A cubic yard weighs from 2,500 to 
 3,000 pounds according to its composition. 
 
 PROPORTIONS OF flATERIALS FOR CONCRETE. 
 
 To manufacture one cubic yard of concrete the following quan- 
 tities of materials are required : 
 
 BROKEN-STONE-AND-GRAVEL CONCRETE. 
 
 Broken-stone 50% of its bulk voids 1 cubic yard 
 
 Gravel to fill voids in the stone . . J " 
 
 Sand to fill voids in the gravel J " 
 
 Cement to fill voids in the sand J " 
 
 BROKEN-STONE CONCRETE. 
 
 Broken stone 50% of its bulk voids .... 1 cubic yard 
 
 Sand to fill voids in the stone ......... % " 
 
 Cement to fill voids in the sand J " 
 
 GRAVEL CONCRETE. 
 
 Gravel J of its bulk voids 1 cubic yard 
 
 Sand to fill voids in the gravel J " 
 
 Cement to fill voids in the sand " 
 
34 MASONRY CONSTRUCTION 
 
 Concrete composed of 1 part Rosendale cement, 2 parts of sand, 
 and 5 parts of broken stone requires: 
 
 Broken stone 0.92 cubic yard 
 
 Sand. ......,.:..;.; 0.37 " 
 
 Cement 1 . 43 barrels 
 
 The usual proportions of the materials in concrete are: 
 ROSENDALE CEMENT CONCRETE. 
 
 Rosendale cement 1 part 
 
 Sand .... 2 parts 
 
 Broken stone 3 to 4 " 
 
 PORTLAND CEMENT CONCRETE. 
 
 Portland cement 1 part 
 
 Sand . . 2 to 3 parts 
 
 Broken stone or gravel 3 to 7 " 
 
 To make 100 cubic feet of concrete of the proportions 1 to 6 will 
 require 5 bbl. cement (original package) and 4.4 yards of stone and 
 sand. 
 
 flixing Concrete. The concrete may be mixed by hand or 
 machinery. In hand-mixing the cement and sand are mixed dry. 
 About half the sand to be used in a batch of concrete is spread evenly 
 over the mortar-board, then the dry cement is spread evenly over 
 the sand, and then the remainder of the sand is spread on top of the 
 cement. The sand and cement are then mixed with a hoe or by 
 turning and re-turning with a shovel. It is very important that the 
 sand and cement be thoroughly mixed. A basin is then formed by 
 drawing the mixed sand and cement to the outer edges of the board, 
 and the whole amount of water required is poured into it. The 
 sand and cement are then thrown back upon the water and thoroughly 
 mixed with the hoe or shovel into a stiff mortar and then levelled off. 
 The broken stone or gravel should be sprinkled with sufficient water 
 to remove all dust and thoroughly wet the entire surface. The 
 amount of water required for this purpose will vary considerably 
 with the absorbent power of the stone and the temperature of the air. 
 The wet stone is then spread evenly over the top of the mortar and 
 the whole mass thoroughly mixed by turning over with the shovel. 
 Two, three, or more turnings may be necessary. It should be turned 
 
MASONRY CONSTRUCTION 35 
 
 until every stone is coated with mortar, and the entire mass presents 
 the uniform color of the cement, and the mortar and stones are uni- 
 formly distributed. When the aggregate consists of broken brick 
 or other porous material it should be thoroughly wetted and time 
 allowed for absorption previous to use; otherwise it will take away 
 part of the water necessary to effect the setting of the cement. 
 
 When the concrete is ready for use it should be quite coherent 
 and capable of standing at a steep slope without the water running 
 from it. 
 
 The rules and the practice governing the mixing of concrete 
 vary as widely as the proportion of the ingredients. It may be stated 
 in general that if too much time is not consumed in mixing the wet 
 materials a good result can be obtained by any of the many ways 
 practised, if only the mixing is thorough. With four men the time 
 required for mixing one cubic yard is about ten minutes. 
 
 Whatever the method adopted for mixing the concrete, it is 
 advisable for the inspector to be constantly present during the opera- 
 tion, as the temptation to economize on the cement and to add an 
 excess of water to lighten the labor of mixing is very great. 
 
 Laying Concrete. Concrete is usually deposited in layers, 
 the thickness of which is generally stated in the specifications for 
 the particular work (the thickness varies between 6 and 12 in.). The 
 concrete must be carefully deposited in place. A very common 
 practice is to tip it from a height of several feet into the trench. This 
 process is objected to by the best authorities on the ground that the 
 heavy and light portions separate while falling, and that the concrete 
 is, therefore, not uniform throughout its mass. 
 
 The best method is to wheel the concrete in barrows, imme- 
 diately after mixing, to the place where it is to be laid, gently tipping 
 or sliding it into position and at once ramming it. 
 
 The ramming should be done before the cement begins to set, 
 and should be continued until the water begins to ooze out upon 
 the upper surface. When this occurs it indicates a sufficient degree 
 of compactness. A gelatinous or quicksand condition of the mass 
 indicates that too much water was used in mixing. Too severe or 
 long-continued pounding injures the strength by forcing the stones 
 to the bottom of the layers and by distributing the incipient "set" 
 of the cement. 
 
36 MASONRY CONSTRUCTION 
 
 The rammers need not be very heavy, 10 to 15 Ib. will be suffi- 
 cient. Square ones should measure from to 8 in. on a side and 
 round ones from 8 to 12 in. in diameter. 
 
 After each layer has been rammed it should be allowed sufficient 
 time to "set", without walking on it or in other ways disturbing it. 
 If successive layers are to be laid the surface of the one already set 
 should be swept clean, wetted, and made rough by means of a pick 
 for the reception of the next layer. 
 
 Great care should be observed in joining the work of one day 
 to that of the next. The last layer should be thoroughly compacted 
 and left with a slight excess of mortar. It should be finished with 
 a level surface, and when partially set should be scratched with a 
 pointed stick and covered with planks, canvas, or straw. In the 
 morning, immediately before the application of the next layer, the 
 surface should be swept clean, moistened with water, and painted 
 with a wash of neat cement mixed with water to the consistency of 
 cream. This should be put on in excess and brushed thoroughly 
 back and forth upon the surface so as to insure a close contact 
 therewith. 
 
 Depositing Concrete Under Water. In laying concrete under 
 water an essential requisite is that the materials shall not fall. 
 from any height through the water, but be deposited in the allotted 
 place in a compact mass; otherwise the cement will be separated 
 from the other ingredients and the strength of the work be seriously 
 impaired. If the concrete is allowed to fall through the water its 
 ingredients will be deposited in a series, the heaviest the stone at 
 the bottom, and the lightest the cement at the top. A fall of even 
 one foot causes an appreciable separation. 
 
 A common method of depositing concrete under water is to 
 place it in a V-shaped box of wood or plate iron, which is lowered 
 to the bottom with a crane. The box is so constructed that on reach- 
 ing the bottom a latch operated by a rope reaching to the surface 
 can be drawn out, thus permitting one of the sloping sides to swing 
 open and allow the concrete to fall out. The box is then raised 
 and refilled. 
 
 A long box or tube, called a tremie, is also used. It consists 
 of a tube open at top and bottom built in detachable sections, so 
 that the length may be adjusted to the depth of water. The tube 
 
MASONRY CONSTRUCTION 37 
 
 ; . _____ 
 
 is suspended from a crane or movable frame running on a track, by 
 which it is moved about as the work progresses. The upper end is 
 hopper-shaped, and is kept above the water; the lower end rests on 
 the bottom. The tremie is rilled in the beginning by placing the 
 lower end in a box with a movable bottom, filling the tube, lowering 
 all to the bottom, and then detaching the bottom of the box. The 
 tube is kept full of concrete by more being thrown in at the top as 
 the mass issues from the bottom. 
 
 Concrete is also successfully deposited under water by enclosing 
 it in paper bags and lowering or sliding them down a chute into 
 place. The bags get wet and the pressure of the concrete soon bursts 
 them, thus allowing the concrete to unite into a solid mass. Concrete 
 is also sometimes deposited under water by enclosing it in open-cloth 
 bags, the cement oozing through the meshes sufficiently to unite the 
 whole into a single mass. 
 
 Concrete should not be deposited in running water unless pro- 
 tected by one or other of the above-described methods; otherwise 
 the cement will be washed out. 
 
 Concrete deposited under water should not be rammed, but if 
 necessary may be levelled with a rake or other suitable tool imme- 
 diately after being deposited. 
 
 When concrete is deposited in water a pulpy, gelatinous fluid 
 is washed from the cement and rises to the surface. This causes 
 the water to assume a milky hue. The French engineers apply the 
 term laitance to this substance. It is more abundant in salt water 
 than in fresh. The theory of its formation is that the immersed 
 concrete gives up to the water, free caustic lime, which precipitates 
 magnesia in a light and spongy form. This precipitate sets very 
 slowly, and sometimes scarcely at all, and its interposition between 
 the layers of concrete forms strata of separation. The proportion 
 of laitance is greatly diminished by using large immersion-boxes, 
 or a tremie, or paper or cloth bags. 
 
 Asphaltic Concrete is composed of asphaltic mortar and 
 broken stone in the proportion of 5 parts of stone to 3 parts of mortar. 
 The stone is heated to a temperature of about 250 F. and added to 
 the hot mortar. The mixing is usually performed in a mechanical 
 mixer. 
 
MASONRY CONSTRUCTION 
 
 The material is laid hot and rammed until the surface is smooth. 
 Care is required that the materials are properly heated, that the 
 place where it is to be laid is absolutely dry and that the ramming 
 is done before it chills or becomes set. The rammers should be heated 
 in a portable fire. 
 
 CLAY PUDDLE. 
 
 Clay puddle is a mass of clay and sand worked into a plastic 
 condition with water. It is used for filling coffer-dams, for making 
 embankments and reservoirs water-tight, and for protecting masonry 
 against the penetration of water from behind. 
 
 Quality of Clay. The clays best suited for puddle are opaque, 
 and not crystallized, should exhibit a dull earthy fracture, exhale 
 when breathed upon a peculiar faint odor termed "argillaceous," 
 should be unctuous to the touch, free from gritty matter, and form 
 a plastic paste with water. 
 
 The important properties of clay for making good puddle are 
 its tenacity or cohesion and its power of retaining water. The tenac- 
 ity of a clay may be tested by working up a small quantity with water 
 into a thoroughly plastic condition, and forming it by hand into a 
 roll about 1 to H inches in diameter by 10 or 12 inches in length. 
 If such a roll is sufficiently cohesive not to break on being suspended 
 by one end while wet the tenacity of the material is ample. 
 
 To test its power of retaining water one to two cubic yards 
 should be worked with water to a compact homogeneous plastic 
 condition, and then a hollow should be formed in the center of the 
 mass capable of holding four or five gallons of water. After filling 
 the hollow with water it should be covered over to prevent evaporation 
 and left for about 24 hours, when its capability of holding water will 
 be indicated by the presence or absence of water in the hollow. 
 
 The clay should be freed from large stones and vegetable matter, 
 and just sufficient sand and water added to make a homogeneous 
 mass. If there is too little sand the puddle will crack by shrinkage 
 in drying, and if too much it will be permeable. 
 
 Puddling. The operation of puddling consists in chopping 
 the clay in layers of about 3 inches thick with spades, aided by the 
 addition of sufficient water to reduce it to a pasty condition. After 
 
MASONRY CONSTRUCTION 39 
 
 each chop and before withdrawing the spade it should be given a 
 lunging motion so as to permit the water to pass through. 
 
 The spade should "pass through the upper layer into the lower 
 layer so as to cause the layers to bond together. 
 
 The test For thorough puddling is that the spade will pass through 
 the layer with ease, which it will not do if there are any dry hard 
 lumps. 
 
 Sometimes in place of spades, harrows are used, each layer of 
 clay being thoroughly harrowed aided by water and then rolled with 
 a grooved roller to compact it. 
 
 The finished puddle should not be exposed to the drying action 
 of the air, but should be covered with a layer of dry clay or sand. 
 
 FOUNDATIONS. 
 
 The foundation is the most critical part of a masonry structure. 
 The failures of masonry work due to faulty workmanship or to an 
 insufficient thickness of the walls are rare in comparison with those 
 due to defective foundations. When it is necessary, as so frequently 
 it is at the present day, to erect gigantic edifices as high buildings 
 or long-span bridges on weak and treacherous soils, the highest 
 constructive skill is required to supplement the weakness of the 
 natural foundation by such artificial preparations as will enable it 
 to sustain the load with safety. 
 
 Natural Foundations. The soils comprised under this head 
 may be divided into two classes. (1) Those whose stability is not 
 affected by water, and which are firm enough to support the structure, 
 such as rock, compact gravels, and hard clay, and (2) soils which are 
 firm enough to support the weight of the structure, but whose stability 
 is affected by water, such as loose gravels, sand, clay and loam. 
 
 Foundations on Rock. To prepare a rock foundation, all 
 that is generally necessary is to cut away the loose and decayed por- 
 tions and to dre'ss the surface so exposed to a plane as nearly perpen- 
 dicular to the direction of the pressure as practicable; or, if the rock 
 forms an inclined plane, to cut a series of plane surfaces, like those 
 of steps, for the walls to rest upon. If there are any fissures in the 
 rock they should be filled with concrete. 
 
 Foundations on Gravel, Etc. In dealing with soils of this 
 kind usually nothing more is required than to cover them with a 
 
40 
 
 MASONRY CONSTRUCTION 
 
 layer of concrete of width and depth sufficient to distribute the weight 
 properly. 
 
 Foundations on Sand. ' Sand is almost incompressible so long 
 as it is not allowed to spread out laterally, but as it has no cohesion, 
 and acts like a fluid when exposed to running water, it must be treated 
 with great caution. 
 
 Foundations on Clay. Clay is much affected by the action 
 of water, and hence the ground should be well drained before the 
 work is begun, and the trenches so arranged that water does not 
 remain in them. In general, the less a soil of this kind is exposed 
 to the action of the air, and the sooner it is protected from exposure, 
 the better for the work. The top of the footings must be carried 
 below the frost line to prevent heaving, and for the same reason the 
 outside face of the wall should be built with a slight batter and per- 
 fectly smooth. The frost line attains a depth of six feet in some of 
 the northern states. 
 
 The bearing power of clay and loamy soils may be greatly in- 
 creased: (1) By increasing the depth. (2) By drainage. This 
 
 may be accomplished by a cover- 
 ing of gravel or sand, the thick- 
 ness depending upon the plas- 
 ticity of the soil, and by surround- 
 ing the foundation walls with a 
 tile drain as in Fig. 5. If springs 
 are encountered the water may 
 be excluded by sheet pilings, 
 puddling or plugging the spring 
 with concrete. (3) By consoli- 
 dating the soil. This ni'iy be 
 done by driving short piles close 
 together, or by driving piles, then 
 withdrawing them an-1 filling the 
 space immediately with damp sand well rammed. If the soil is very 
 loose and wet, sand will not be effective, and concrete will be found 
 more satisfactory. 
 
 Artificial Foundations. When the ground in its natural 
 state is too soft to bear the weight of the proposed structure, recourse 
 must be had to artificial means of support, and, in doing this, whai- 
 
 Fig. 5. Drainage of Foundation Walls. 
 
MASONRY CONSTRUCTION 41 
 
 ever mode of construction is adopted, the principle must always be 
 that of extending the bearing surface as much as possible. 
 
 Foundations on Mud, silt, marshy or compressible soils are 
 generally formed in one of three ways: (1) By driving piles in which 
 the footings are supported. (2) By spreading the footings either 
 by layers of timber, steel beams, or concrete, or a combination of 
 either. (3) By sinking caissons of iron or steel, excavating the soil 
 from the interior, and filling with concrete. 
 
 Foundations in Water are formed in several ways: (1) 
 Wholly of piles. (2) Solid foundations laid upon the surface of 
 the ground by means of cribs, caissons, or piles, and grillage. (3) 
 Solid foundations laid 60/010 the surface, the ground being made dry 
 by cofferdams or caissons. (4) Where the site is perfectly firm, 
 and there is no danger of the work being undermined by scour, 
 foundations are started on the surface, the inequalities being first 
 removed by blasting or dredging. The simplest foundation of this 
 class is called "Random" work or Pierre perdue. It is formed by 
 throwing large masses of stone upon the site until the mass reaches 
 the surface of the water, above which the work can be carried on in 
 the usual manner. Large rectangular blocks of stone or concrete 
 are also used, the bottom being first simply leveled and the blocks 
 carefully lowered into place. 
 
 PILE FOUNDATIONS. 
 
 Timber Piles are generally round, the diameter at the butt 
 varying from 9 to 18 inches. They should be straight-grained and 
 as free from knots as possible. The variety of timber is usually 
 selected according to the character of the soil. Where the piles 
 will be always under water and where the soil is soft, spruce and hem- 
 locks are used. For firm soils the hard pines, fir, elm and beech are 
 preferable. Where the piles will be alternately wet and dry, white 
 or black oak and yellow pine are used. Piles exposed to tide water 
 are generally driven with the bark on. It is customary to fix an iron 
 hoop to the heads of piles to prevent their splitting, and also to have 
 them shod with either cast- or wrought-iron shoes. 
 
 Timber piles when partly above and partly under water, decay 
 rapidly at the water line owing to the alternations of dryness and 
 moisture. In tidal waters they are destroyed by the marine worm 
 
42 
 
 MASONRY CONSTRUCTION 
 
 called the "teredo navalis." To preserve timber in such situations 
 several processes are in use. The one most extensively employed 
 is known as " creosoting, " which consists of injecting creosote or 
 
 dead oil of coal tar into 
 the pores of the timber. 
 The frame of timbers 
 placed on the top of the 
 piles is called the grillage. 
 The piles are sawed off 
 square below low water, 
 a timber called a cap is 
 placed on the ends of 
 the piles and fastened 
 with drift bolts, and 
 
 Fig. 6. Timber Pile Foundation. 
 
 transverse timbers called 
 strips are placed on the 
 
 caps and drift-bolted to them. As many courses as necessary may be 
 added, each at right angles to the one below it, the top courses being 
 either laid close together to form a floor or else covered with heavy 
 plank to receive the masonry. 
 
 In some cases the grillage is omitted, a layer of concrete being 
 used instead, with the heads of the piles embedded therein, as shown 
 in Fig. 7. The name gril- 
 lage is also applied to a '^ ea-s^ 
 
 combination of steel beams 
 and concrete. 
 
 Iron and Steel Piles. 
 Cast iron, wrought iron, 
 and steel are employed for 
 ordinary bearing piles, sheet 
 piles, and for cylinders. 
 Iron cylinders are usually 
 .sunk either by dredging the 
 soil from the inside or by 
 the pneumatic process. 
 
 Cast-iron piles are used 
 as substitutes for wooden ones. Lugs or flanges are usually cast on 
 the sides of die piles, to which bracing may be attached for securing 
 
 r 
 
 Fig. 7. Timber Piles, Concrete Capping, and 
 I-Beam Grillage. 
 
MASONRY CONSTRUCTION 
 
 them in position. A wooden block is laid on top of the pile to 
 receive the blows of the hammer, and after being driven a cap with 
 a socket in its lower side is placed upon the pile to receive the load. 
 Solid rolled-steel piles are driven in the same manner as timber 
 piles, either with a hammer, machine or water-jet. 
 
 Screw Piles are piles which are screwed into 
 the stratum in which they are to stand. They 
 are ordinary piles of timber or iron (the latter 
 usually hollow), to the bottom of which a screw ' 
 disk, consisting of a single turn of the spiral, similar 
 to the bottom turn of an auger, is fastened by 
 bolts or pins. Instead of driving these piles into 
 the ground they are forced in by turning with 
 levers or machinery suitable for the purpose. 
 The screw disks vary in diameter from 1 to 6 
 feet. The water jet is sometimes employed by 
 applying it to the under, upper, or both sides of 
 the disk for the purpose of reducing the resistance. 
 
 Concrete Piles. Two methods of forming 
 these piles are in use. (1) The piles are made 
 in moulds and carried to the place of use and 
 driven in' the same manner as timber piles. (2) 
 Holes are made in the ground and rilled with 
 concrete. 
 
 Moulded Concrete Piles. Fig. 8 shows the 
 moulded pile. This pile is made in moulds and 
 contains four vertical rods a at the corners, the 
 rods are stayed by loops or hooks b of large wire 
 sprung into place across the sides of the pile and 
 held transversely by horizontal strips of thin 
 metal. The feet of the piles are either wedge Section A-B 
 
 shaped or pyramidal and are protected by cast- Fig. 8. Moulded con- 
 iron points with side plates which turn in at c to 
 lock with the concrete. The upper ends of the piles are shouldered in 
 to give clearance for the driving cap d. This is a cast steel hood 
 which fits loosely around the neck of the pile, and is filled with dry 
 sand or a bag of sawdust d f retained by a clay ring and hemp jacket 
 e at the bottom of the cap. 
 
44 
 
 MASONRY CONSTRUCTION 
 
 Fig. y. 
 
 OlA 
 
 Concrete Pile. 
 
 The sand absorbs the impact of the hammer so as to permit 
 the piles to be driven safely, and it raises the hood sufficiently above 
 the top of the pile to permit the reinforcement rods to extend beyond 
 the concrete for connection with the superstructure. 
 
 Concrete Piles Formed in Place. Fig. 9 shows this type 
 of pile. The hole is made by driving with an ordinary pile-driving 
 apparatus, a sheet steel tube tapering from 20 inches 
 
 at the top to 6 inches at 
 the bottom, the tube is 
 driven by means of a col- 
 lapsible core which is with- 
 drawn. When the desired 
 depth is reached, the tube 
 is then filled with concrete. 
 Fig. 10 shows another 
 method of forming this type 
 of pile. A sheet steel shell 
 is formed by telescopic sec- 
 tions, each section is 8 ft. 
 long and has at its upper 
 end projections which en- 
 gage with projections on 
 the lower end of the next 
 section. To the bottom sec- 
 tion is attached a cast iron 
 point with a f-in. jet hole 
 or nozzle, to which is fitted 
 a 2J-in. pipe, this pipe is 
 held in place by spreaders and remains in place in the finished pile, 
 to which it adds lateral strength. The shell is sunk by water jet and 
 
 filled with concrete. 
 
 PILE-DRIVING. 
 
 Timber piles are driven either point or butt end down; the latter 
 is considered the better method. When piles are directed to be 
 sharpened the points should have a length of from one and a half 
 times to twice the diameter. 
 
 To prevent the head of the pile from being broomed or split 
 by the blows of the driving-ram it is bound with a wrought-iron 
 
 Fig. 10. Con- 
 crete Pile. 
 
MASONRY CONSTRUCTION 45 
 
 hoop, 2 to 3 inches wide and J to 1 inch thick. Instead of the wrought- 
 iron band a cast-iron cap is sometimes used. It consists of a block 
 with a tapering recess above and below, the chamfered head of the 
 pile fitting into the one below, and a cushion piece of hard wood upon 
 which the hammer falls fitting into the one above. 
 
 When brooming occurs the broomed part should be cut off, 
 because a broomed head cushions the blow and dissipates it without 
 any useful effect. Piles that split or broom excessively or are other- 
 wise injured during the driving must be drawn out. 
 
 Bouncing of the hammer occurs when the pile refuses to drive 
 further, or it may be caused by the hammer being too light, or its 
 striking velocity being too great, or both. The remedy for bouncing 
 is to diminish the fall. 
 
 Excessive hammering on piles which refuse to move should be 
 avoided, as they are liable to be crippled, split, or broken below the 
 ground. Such injury will pass unnoticed and may be the cause of 
 future failure. 
 
 As a general rule, a heavy hammer with a low fall drives more 
 satisfactorily than a light one with a high fall. More blows can be 
 made in the same time with a low fall, and this gives less time for 
 the soil to compact itself around the piles between the blows. At 
 times a pile may resist the hammer after sinking some distance, but 
 start again after a short rest; or it may refuse a heavy -hammer and 
 start under a light one. It may drive slowly at first, and more 
 rapidly afterwards, from causes difficult to discover. 
 
 The driving of a pile sometimes causes adjacent ones previously 
 driven to spring upwards several feet. The driving of piles in soft 
 ground or mud will generally cause adjacent ones previously driven 
 to lean outwards unless means of prevention be taken. 
 
 A pile may rest upon rock and yet be very weak, for if driven 
 through very soft soil all the pressure is borne by the sharp point, and 
 the pile becomes merely a column in a worse condition than a pillar 
 with one rounded end. In such soils the piles need very little sharp- 
 ening; indeed, they had better be driven butt end down without any 
 point. Solid metal piles are usually of uniform diameter and are 
 driven with either blunt or sharpened points. 
 
 Piles are driven by machines called pile drivers. A pile driver 
 consists essentially of two upright guides or leads, often of great 
 
46 MASONRY CONSTRUCTION 
 
 height, erected upon a platform, or on a barge when used in water. 
 These guides serve to hold the pile vertical while being driven, and 
 also hold and guide the hammer used in driving. This is a block 
 of iron called a ram, monkey, or hammer, weighing anywhere from 
 800 to 4,000 pounds, usually about 2,000 to 3,000 pounds. The 
 accessories are a hoisting engine for raising the hammer and the 
 devices for allowing it to drop freely on the heads of the piles. 
 
 The steam hammer is also employed for driving piles, and has 
 certain advantages over the ordinary form, the chief of which lies 
 in the great rapidity with which the blows follow one another, allow- 
 ing no time for the disturbed earth, sand, etc., to recompact itself 
 around the sides and under the foot of the pile. It is less liable than 
 other methods to split and broom the piles, so that these may be of 
 softer and cheaper wood, and the piles are not so liable to " dodge" 
 or get out of line. 
 
 When piles have to be driven below the end of the leaders of 
 the pile driver a follower is used. This is made from a pile of suita- 
 ble length placed on top of the pile to be driven. To prevent its 
 bouncing off caps of cast iron are used, one end being bolted to the 
 follower and the other end fitting over the head of the pile. 
 
 Piles are also driven by the "water jet." This process consists 
 of an iron pipe fastened by staples to the side of the pile, its lower end 
 placed near the point of the pile and its upper end connected by a 
 hose to a force pump. The pile can be sunk through almost any 
 material, except hardpan and rock, by forcing water through the 
 pipe. It seems to make very little difference, either in the rapidity 
 of sinking or in the accuracy with which the pile preserves its position, 
 whether the nozzle is exactly under the middle of the pile or not. 
 
 The efficiency of the jet depends upon the increased fluidity 
 given the material into which the piles are sunk, the actual displace- 
 ment of material being small. Hence the efficiency of the jet is 
 greatest in clear sand, mud, or soft clay. In gravel or in sand con- 
 taining a large percentage of gravel, or in hard clay the jet is almost 
 useless. For these reasons the engine, pump, hose, and nozzle 
 should be arranged to deliver large quantities of water with a moder- 
 ate force rather than smaller quantities with high initial velocity. 
 In gravel, or in sand containing gravel, some benefit might result from 
 a velocity sufficient to displace the pebbles and drive them from the 
 
MASONRY CONSTRUCTION 
 
 47 
 
 vicinity of the pile. The error most frequently made in the applica- 
 tion of the water jet is in using pumps with insufficient capacity. 
 
 The approximate volume of water required per minute, per 
 inch of average diameter of pile, for penetrations under 40 feet is 
 16 gallons; for greater depths the increase in the volume of water 
 is approximately at the rate of 4 gallons per inch- of diameter of pile 
 per minute, for each additional 10 feet of penetration. 
 
 The number and size of pipes required for various depths are 
 about as follows: 
 
 TABLE 7. 
 
 Depth of 
 penetration, 
 
 feet. 
 
 Diameter of 
 pipe, inches. 
 
 Number of 
 pipes. 
 
 Diameter 
 of nozzle, 
 inches. 
 
 20 
 
 2 
 
 1 
 
 i 
 
 30 
 
 2$ 
 
 1 
 
 it 
 
 40 
 
 2* 
 
 2 
 
 it 
 
 50 
 
 2* 
 
 2 
 
 i 
 
 60 
 
 2^ 
 
 2 
 
 I 
 
 When the descent of the pile becomes slow, or it sticks or " brings 
 up " in some tenacious material, it can usually be started by striking 
 a few blows with the pile-driving hammer, or by raising the pile about 
 6 inches and allowing it to drop suddenly, with the jet in operation. 
 By repeating the operation as rapidly as possible the obstruction will 
 generally be overcome. 
 
 It is an advantage to use an ordinary pile-driving machine for 
 sinking piles with the water jet. The hammer being allowed to rest 
 upon the head of the pile aids in accelerating the descent, and light 
 blows can be struck as often as may appear necessary. The effi- 
 ciency of the jet can also be greatly increased by bringing the weight 
 of the pontoon upon which the machinery is placed to bear upon 
 the pile by means of a block and tackle. 
 
 Splicing Piles. It frequently happens in driving piles in 
 swampy places, for false works, etc., that a single pile is not long 
 enough, in which case two are spliced together. A common method 
 of doing this is as follows. After the first pile is driven its head is 
 cut off square, a hole 2 inches in diameter and 12 inches deep is 
 
48 
 
 MASONRY CONSTRUCTION 
 
 bored in its head, and an oak treenail or dowel-pin 23 inches long 
 is driven into the hole; another pile similarly squared and bored is 
 placed upon the lower pile, and the driving continued. Spliced in 
 this way the pile is deficient in lateral stiffness, and the upper section 
 is liable to bounce off while driving. It is better to reinforce the 
 splice by flattening the sides of the piles and nailing on with, say, 8- 
 inch spikes four or more pieces 2 or 3 inches thick, 4 or 5 inches wide, 
 and 4 to 6 feet long. 
 
 CONCRETE WITH STEEL BEAHS. 
 
 The foundation is prepared by first laying a bed of concrete 
 to a depth of from 4 to 12 inches and then placing upon it a row of 
 
 bib' IrPlaned loiat. 
 
 J 
 
 Fig. 11. Concrete, and Steel I-Beams. 
 
 I-beams at right angles to the face of the wall. In the case of heavy 
 piers, the beams may be crossed in two directions. Their distance 
 apart, from center to center, may vary from 9 to 24 inches, according 
 
MASONRY CONSTRUCTION 
 
 to circumstances, i.e., length of their projection beyond the masonry, 
 thickness of concrete, estimated pressure per square foot, etc. They 
 should be placed far enough apart to permit the introduction of the 
 concrete filling and its proper tamping. 
 
 Hollow Cylinders of cast iron or plate steel, commonly called 
 caissons, are frequently used with advantage. The cylinders are 
 made in short lengths with internal flanges and are bolted together 
 as each preceding length is lowered. They are sunk by excavating 
 the natural soil from the interior. When the stratum on which they 
 are to rest has been reached they are filled with concrete. 
 
 Cofferdams. There are many circumstances under which it 
 becomes necessary to expose the bottom and have it dry before 
 commencing operations. This is done by enclosing the site of the 
 foundation with a w r ater-tight wall. The great difficulties in the 
 construction of a cofferdam in deep water are, first, to keep it water- 
 
 Fig. 12. Cofferdam, 
 
 tight, and, second, to support the sides against the pressure of the 
 water outside. Fig. 12 shows the simplest form; it consists of two 
 rows of piles driven closely and filled with clay puddle. In shallow 
 water and on land sheet piling is sometimes sufficient. 
 
 Sheet Piles are flat piles, usually of plank, either tongued and 
 grooved or grooved only, into which a strip of tongue is driven; or 
 they may be of squared timber, in which case they are called "close 
 piles," or of sheet iron. The timber ones are of any breadth that 
 can be procured, and from 2 to 10 inches thick, and are shaped at 
 the lower end to an edge wholly from one side ; this point being 
 placed next to the last pile driven tends to crowd them together and 
 
50 
 
 MASONRY CONSTRUCTION 
 
 make tighter joints (the angle formed at the point should be 30). 
 In stony ground they are shod with iron. 
 
 When a space is to be enclosed with sheet piling two rows of 
 guide piles are first driven at regular intervals of from 6 to 10 feet, 
 and to opposite sides of these near the top are notched or bolted a 
 pair of parallel string pieces or "wales, " from 5 to 10 inches square, 
 so fastened to the guide piles as to leave between the wales equal to the 
 thickness of the sheet piles. 
 
 If the sheeting is to stand more than 8 or 10 feet above the ground, 
 a second pair of wales is required near the level of the ground. The 
 sheet piles are driven between the wales, working from each end 
 towards the middle of the space between a pair of guide piles, so that 
 the la^t or central pile acts as a wedge to tighten the whole. 
 
 Sheet piles are driven either by mauls wielded by men or by a 
 pile-driving machine. Ordinary planks are also used for sheet 
 
 Fig. 13. Sheet Piling. 
 
 piling, being driven with a lap; such piling is designated as "single 
 lap," "double lap," and "triple lap." The latter is also known as 
 the "Wakefield" triple-lap sheet piling, shown in Fig. 13. 
 
 Cribs are boxes constructed of round or square timber, divided 
 by partitions of solid timber into square or rectangular cells. The 
 cells are floored with planks, placed a little above the lower edge so 
 as not to prevent the crib from settling slightly into the soil, and thus 
 coming to a full bearing on the bottom. After it has been sunk the 
 cells are filled with sand and stone. On uneven rock bottom it may 
 be necessary to scribe the bottom of the crib to fit the rock. In some 
 cases rip-rap is deposited outside around the crib to prevent under- 
 
MASONRY CONSTRUCTION 
 
 51 
 
 mining by the current. A crib with only an outside row of cells for 
 sinking it is sometimes used, with an interior chamber in which con- 
 crete is laid under water and the masonry started thereon. Cribs 
 are sometimes sunk into plac*? and then piles are driven in the cells, 
 which are afterward filled with concrete or broken stone. The masonry 
 may then rest on the piles only, 
 which in turn will be protected by 
 the crib. If the bottom is liable 
 to scour, sheet piles or rip-rap 
 may be placed outside around the 
 base of the crib. Cribs with 
 only an outer row of cells for 
 puddling may be used as a coffer- 
 dam, the joints between the outer 
 timbers being well calked, and 
 care taken by means of outside 
 pile planks to prevent water from 
 entering beneath it. 
 
 Caissons are of two forms, 
 the " erect" or "open" and the 
 "inverted." The former is a 
 strong water-tight timber box, 
 which is floated over the site of 
 the work, and being kept in place 
 
 by guide piles, is loaded with 
 stone until it rests firmly on the 
 ground. In some cases the stone 
 is merely thrown hi, the regular 
 masonry commencing with the 
 top of the caisson ; which is sunk 
 a little below the level of low 
 water, so that the whole of the 
 timber is always covered, and 
 the caisson remains as part of the structure. In others, the ma- 
 sonry is built on the bottom of the caisson, and when the work 
 reaches the level of the water the sides of the caisson are removed. 
 The site is prepared to receive the caisson by dredging and depositing 
 a layer of concrete, or by driving piles, or a combination of both. 
 
 Fig. 14. Building on Pile Foundation. 
 
52 MASONRY CONSTRUCTION 
 
 The inverted caisson is also a strong water-tight box, open at the 
 bottom and closed at the top, upon which the structure is built, and 
 which sinks as the. masonry is added. This type of caisson is usual] v 
 aided in sinking by excavation made in the interior. The processes 
 employed to aid the sinking of the inverted caissons are called the 
 "vacuum" and the "plenum." 
 
 The vacuum process consists in exhausting the air from the 
 interior of the caisson, and using the pressure of the atmosphere upon 
 the top of it to force it down. Exhausting the air allows the water to 
 flow past the lower edge into the interior, thus loosening the soil. 
 
 The plenum or compressed-air process consists in pumping air 
 into the chamber of the caisson, which by its pressure excludes the 
 water. An air lock or entrance provided with suitable doors is ar- 
 ranged in the top of the caisson, by which workmen can enter to 
 loosen up the soil and otherwise aid in the sinking of the caisson 
 vertically by removing and loosening the material at the sides. If 
 the loosened material is of a suitable character it is removed with a 
 sand pump; if not, hoisting apparatus is provided and, being loaded 
 into buckets by the workmen, it is hoisted out through the air lock. 
 
 Freezing Process. This process is employed in sinking 
 foundation- pits through quicksand and soils saturated with water. 
 The Poctsch-Sooysmith process is to sink a series of pipes 10 inches 
 in diameter through the earth to the rock; these are sunk in a circle 
 around the proposed shaft. Inside of the 10-inch pipes 8-inch pipes 
 closed at the bottom are placed, and inside of these are placed smaller 
 pipes open at the bottom. Each set of the small pipes is connected 
 in a series. A freezing mixture is then allowed to flow downwards 
 through one set of the smaller pipes and return upwards through the 
 other. The freezing mixture flows from a tank placed at a suffic- 
 ient height to cause the liquid to flow with the desired velocity through 
 the pipes. The effect of this process is to freeze the earth into a solid 
 
 wall. 
 
 DESIGNING THE FOUNDATION. 
 
 Load to be Supported. The first step is to ascertain the load 
 to be supported by the foundation. This load consists of three parts : 
 (1) The structure itself, (2) the movable loads on the floors and the 
 snow on the roof, and (3) the part of the load that may be transferred 
 from one part of the foundation to the other by the force of the wind. 
 
MASONRY CONSTRUCTION 
 
 The weight of the building is easily ascertained by calculating the 
 cubical contents of all the various materials in the structure. The fol- 
 lowing data will be useful in determining the weight of the structure. 
 
 TABLE 8. 
 Weight of Masonry. 
 
 Kind of Masonry. 
 
 Weight in 
 Ib. per cu. ft. 
 
 Brickwork, pressed brick, thin joints 
 
 ordinary quality 
 
 soft brick, thick joints 
 
 Concrete 
 
 Granite or limestone, well dressed throughout 
 
 rubble, well dressed with mortar .... 
 
 roughly dressed with mortar 
 
 well dressed, dry 
 
 roughly dressed, dry 
 
 Mortar dried 
 
 Sandstone, -fa less than granite 
 
 145 
 125 
 100 
 
 130 to 160 
 165 
 155 
 150 
 140 
 125 
 100 
 
 Ordinary lathing and plastering weighs about 10 Ib. per sq. ft. 
 Floors weigh approximately: 
 
 Dwellings 10 Ib. per sq. ft. 
 
 Public buildings 25 Ib. per sq. ft. 
 
 Warehouses 40 to 50 Ib. per sq. ft. 
 
 Roofs vary according to the kind of covering, span, etc. 
 Shingle roof weighs about 10 Ib. per sq. ft. 
 
 Slate or corrugated iron 25 Ib per sq. ft. 
 
 The movable load on the floor depends upon the nature of the 
 building. It is usually taken as follows: 
 
 Dwellings 10 Ib. per sq. ft. 
 
 Office buildings 20 Ib. per sq. ft. 
 
 Churches, theatres, etc 100 Ib. per sq. ft. 
 
 Warehouses, factories 100 to 400 Ib. per sq. ft. 
 
 The weight of snow on the roof will vary from in a warm 
 climate to 20 Ib. in the latitude of Michigan. The pressure of the 
 wind is usually taken at 50 Ib. per sq. ft. on a flat surface perpendicu- 
 lar to the wind, and on a cylinder at about 40 Ibs. per sq. ft. over the 
 vertical projection of the cylinder. 
 
MASONRY CONSTRUCTION 
 
 Bearing Power of Soils. The best method of determining 
 the load which a particular soil will bear is- by direct experiment and 
 examination particularly of its compactness and the amount of 
 water it contains. The values given in the following table may be 
 considered safe for good examples of the kind of soil quoted. 
 
 TABLE 9. 
 Bearing Power of Soils. 
 
 Kind of soil. 
 
 Bearing power, 
 tons per square foot. 
 
 Min. Max. 
 
 Rock hard 
 
 25 
 5 
 4 
 2- 
 1 
 8 
 4 
 2 
 0.5 
 
 30 
 10 
 6 
 4 
 2 
 10 
 6 
 4 
 1 
 
 " so ft 
 
 Clay on thick bed always dry 
 
 " " " " moderately dry . . 
 
 " soft . 
 
 Gravel and coarse sand well cemented 
 
 Sand compact and well cemented 
 
 " clean dry - 
 
 Quicksand alluvial soil etc 
 
 
 Area Required. Having determined the pressure which may 
 safely be brought upon the soil, and having ascertained the weight 
 of each part of the structure, the area required for the foundation 
 is easily determined by dividing the latter by the former. Then, 
 having found the area required, the base of the structure must be 
 extended by footings of concrete, masonry, timber, etc., so as to (1) 
 cover that area and (2) distribute the pressure uniformly over it. 
 
 Bearing Power of Piles. Several formulas have been proposed 
 and are in use for determining the safe working loads on piles. The 
 three in general use are : 
 
 Sander's formula. 
 
 , . Weight of hammer in Ib. X fall in inches. 
 
 Safe load in Ib. = .,. . 
 
 8 X Sinking at last blow. 
 
 Trautwine's formula. 
 Extreme load in tons of 2240 Ibs. = 
 
 Cube root of fall in feet X Weight of hammer in Ib. X 0.023 
 
 Last sinking in inches. 
 
 Safe load to be taken at one-half of extreme load when driven in 
 firm soils, and at one-fourth when driven in river mud or marshy soil. 
 
MASONRY CONSTRUCTION 
 
 55 
 
 Engineering News formula is the latest and is considered reliable. 
 
 Safe load in Ib. = 
 
 S + 1 
 
 in which w = weight of hammer in Ib., h == its fall in feet, S = aver- 
 age sinking under last blows in inches. 
 
 Example of Pile Foundation. As an example of the method 
 of determining the number of piles required to support a given build- 
 ing, the side walls of a warehouse are selected, a vertical section of 
 which is shown in Fig. 15. The walls are of 
 brick, and the weight is taken at 110 pounds per 
 cubic foot of masonry. - 
 
 The piles are to be driven in two rows, 
 spaced two feet between centers, and it has 
 been found that a test pile 20 feet long and 10 
 inches at the top will sink one inch under a 
 1,200-pound hammer falling 20 feet after the 
 pile has been entirely driven into the soil. 
 What distance should the piles be placed center to center length- 
 wise of the wall ? 
 
 By calculation it is found that the wall contains 157J cubic feet 
 of masonry per running foot, and hence weighs 17,306 pounds. The 
 load from the floors which comes upon the wall is: 
 
 From the 1st floor. . . 1500 Ib. 
 
 Fig. 15. Stone 
 Footing. 
 
 3rd " 
 
 1380 
 
 4th " 
 
 ... 700 
 
 5th " . . 
 
 790 
 
 6th " 
 
 .... 790 
 
 roof . 
 
 . 240 
 
 Total 0730 Ib. 
 
 Hence the total weight of the wall and its load per running foot is 
 24,036 pounds. 
 
 The load which one pile will support is, by Sander's rule 
 
 1200 X 240 
 
 = 36,000 pounds. 
 
 o X 1 
 
 By Trautwine's rule, using a factor of safety of 2.5, the safe load 
 would be 
 
56 MASONRY GONSTRUCTK )X 
 
 
 X 1200 X 0.023 
 
 = 15 tons or 33,600 Ib. 
 
 Z.O X (1 i i) 
 
 Then one pair of piles would support 72,000 or 07,200 pounds ac- 
 cording to which rule we take. 
 
 Dividing these numbers by the weight of one foot of the wall 
 and its load, it is found, that, by Sander's rule, one pair of piles will 
 support 3 feet of the wall, and, by Trautwine's rule, 2.8 feet of wall; 
 hence the pile should be placed. 2 feet 9 inches or 3 feet between 
 centers. 
 
 DESIGNING THE FOOTING. 
 
 The term footing is usually understood as meaning the bottom 
 course or courses of concrete, timber, iron, or masonry employed 
 to increase the area of the base of the walls, piers, etc. What- 
 ever the character of the soil, footings should extend beyond 
 the fall of the wall (1) to add to the stability of the structure 
 and lessen the danger of its being thrown out of plumb, and 
 (2) to distribute the weight of the structure over a larger 
 area and thus decrease the settlement due to compression of the 
 ground. 
 
 Offsets of Footings. The area of the foundation having been 
 
 determined and its center having been located with reference to the 
 
 axis of the load, the next step is to deter- 
 
 v _ ^Bricks _ H mine how much narrower each footing 
 
 | ' course may be than the one next below it. 
 ' . ' ' 
 
 T j | | -| The proper offset for each course will 
 
 i*" '',',' r- 1 depend upon the vertical pressure, the 
 
 Fig. K5. Bru-k Footing. transverse strength of the material, and 
 
 the thickness of the course. Each footing 
 
 may be regarded as a beam fixed at one end and uniformly 
 loaded. The part of the footing course that projects beyond 
 the one above it, is a cantilever beam uniformly loaded. From 
 the formulas for such beams, the safe projection may be cal- 
 culated. 
 
 Stone Footings. Table 10 gives the safe offset for masonry 
 footing courses, in terms of the thickness of the course, computed 
 for a factor of safety of 10. 
 
MASONBY CONSTRUCTION 
 
 57 
 
 TABLE 10. 
 
 Kind of stone. 
 
 R* 
 in Ib. per 
 sq. in. 
 
 Offset for a pressure 
 in tons per sq. ft. on 
 the bottom of the 
 course of 
 
 0.5 1.0 2.0 
 
 Bluestone 
 
 ft* 
 
 9 7OH 
 
 3 6 
 
 (\ 
 
 1 8 
 
 (Jranite . 
 
 1 800 
 
 2 
 
 9 1 
 
 
 limestone 
 
 
 i 2 7 
 
 1 
 
 1 3 
 
 Sandstone 
 
 
 1,200 
 
 2.6 
 
 1.8 
 
 1.3 
 
 
 Slate 
 
 
 5,400 
 
 5.0 
 
 3.6 
 
 2.5 
 
 
 
 Best hard 
 
 l>rick 
 
 1,500 
 
 2.7 
 
 1.9 
 
 1.3 
 
 
 Hard brick 
 
 800 
 
 1 Q 
 
 1 4 
 
 8 
 
 Concrete 1 
 
 Portland j 
 
 
 
 
 
 2 
 
 Sand / 10 davs old . . 
 
 l r )0 
 
 8 
 
 6 
 
 4 
 
 3 
 
 Pebbles ) 
 
 
 
 
 
 Concrete 1 
 
 Rosendale ) 
 
 
 
 
 
 2 
 
 Sand > 10 days old .... 
 
 80 
 
 0.6 
 
 0.4 
 
 0.3 
 
 3 
 
 Pebbles \ 
 
 
 
 
 
 * Modulus of rupture. 
 
 To illustrate the method of using the preceding table, assume 
 that it is desired to determine the offset for a limestone footing course 
 when the pressure on the bed of the foundation is 1 ton per square 
 foot, using a factor of safety of 10. On the table, opposite limestone, 
 in next to the last column, we find the quantity 1 .0. This shows that 
 under the conditions stated, the offset may be 1.9 times the thickness 
 of the course. 
 
 Planff 
 Fig 17. Timber Footing. 
 
 Timber Footing. The rise of the transverse timbers (Fig. 17) 
 may be calculated by the following formula: 
 
 2 Xw xy X s 
 Breadth in inches = TV s/ A 
 
 D /N A. 
 
58 
 
 MASONRY CONSTRUCTION 
 
 in which w = the bearing power in 11). per sq. ft.; 
 p ~ the projection of the beam in feet; 
 s = the distance between centers of beams in feet; 
 D = the assumed depth of the beam in inches; 
 A = the constant for strength which is taken for Georgia 
 pine at 90, oak 65, Norway pine GO, white pine or spruce 55. 
 
 Steel I=Beam Footings. The dimensions of the I-beams, Fig. 
 18, can be calculated by the usual formulas, by means of the strain 
 
 1 
 
 I I 
 
 _ 
 
 illLLLLL. , 
 
 1 
 
 ! 1 
 
 "-^ lO'O" ^ 
 
 k ....... - ........... I3'0"- 
 
 Fig. 18. Steel I-IJeam Footing. 
 
 to which the part of the beam in cantilever is submitted* The safe 
 load per running foot is given by the expression 
 
 in which W == load in pounds per running foot; 
 
 S = 10,000 Ib. per sq. in., extreme fibre strain of beams; 
 m = distance from center of gravity of sections to top or 
 
 bottom; 
 I == moment of inertia of section, neutral axis through 
 
 center of gravity; 
 'z = span in feet. 
 
 A ready method of determining the size of the beams is by com- 
 puting the required coefficient of strength, and finding in the tables 
 furnished by the manufacturers of steel beams the size of the beam 
 

 .a& 
 
 H 8 
 
 9115- 
 
 SJJI 
 
 c g ce- 
 
 g S sa 
 
 w || 
 
 <3 Q ta4 
 
 ^ O 
 
MASONRY CONSTRUCTION 
 
 59 
 
 which has a coefficient equal to, or next above, the value obtained by 
 the formula. C, the coefficient, is found by the following expression : 
 
 C = 4XwXp 2 Xs 
 
 in which w = bearing power in pounds per sq. ft.; 
 p = the projection of the beam in feet; 
 s the spacing of the beam, center to center, in feet. 
 Table 11 gives the safe projection of steel I-beams spaced on I 
 foot centers and for loads varying from 1 to 5 tons per sq. ft. 
 
 TABLE 11. 
 Safe Projection of I=Beam Footings. 
 
 b (Tons per Square Foot). 
 
 Depth of 
 beam, in. 
 
 Weight 
 per foot, 
 Ib. 
 
 20 
 
 '80 
 
 20 
 
 64 
 
 15 
 
 75 
 
 15 
 
 60 
 
 15 
 
 50 
 
 15 
 
 41 
 
 12 
 
 40 
 
 12 
 
 32 
 
 10 
 
 33 
 
 10 
 
 25.5 
 
 9 
 
 27 
 
 9 
 
 21 
 
 8 
 
 22 
 
 8 
 
 18 
 
 7 
 
 20 
 
 7 
 
 15.5 
 
 6 
 
 16 
 
 6 
 
 13 
 
 5 
 
 13 
 
 5 
 
 10 
 
 4 
 
 10 
 
 4 
 
 7.5 
 
 1 
 
 1 
 
 13* 
 
 2 
 
 254 
 
 2y 2 
 
 3 
 
 3% 
 
 4 
 
 4% 
 
 5 
 
 14.0 
 
 12.5 
 
 11.5 
 
 10.0 
 
 9.0 
 
 9.0 
 
 8.0 
 
 7.5 
 
 7.0 
 
 6.5 
 
 6.0 
 
 12.5 
 
 ll.C 
 
 10.0 
 
 8.5 
 
 8.0 
 
 8.0 
 
 7.0 
 
 6.5 
 
 6.0 
 
 6.0 
 
 5.5 
 
 11.5 
 
 10.5 
 
 9.5 
 
 8.0 
 
 7.5 
 
 7.5 
 
 6.5 
 
 6.0 
 
 6.0 
 
 5.5 
 
 5.0 
 
 10.5 
 
 9.5 
 
 8.5 
 
 7.5 
 
 7.0 
 
 6.5 
 
 6.0 
 
 5.5 
 
 5.5 
 
 5.0 
 
 5.0 
 
 9.5 
 
 8.5 
 
 8.0 
 
 7.0 
 
 6.5 
 
 6.0 
 
 5.5 
 
 5.0 
 
 5.0 
 
 4.5 
 
 4.5 
 
 8.5 
 
 8.0 
 
 7.0 
 
 6.0 
 
 6.0 
 
 5.5 
 
 5.0 
 
 4.5 
 
 4.5 
 
 4.0 
 
 4.0 
 
 8.0 
 
 7.0 
 
 6.5 
 
 5.5 
 
 5.5 
 
 5.0 
 
 4.5 
 
 4.0 
 
 4.0 
 
 3.5 
 
 3.5 
 
 7.0 
 
 6.5 
 
 5.5 
 
 5.0 
 
 4.5 
 
 4.5 
 
 4.0 
 
 4.0 
 
 3.5 
 
 3.5 
 
 3.0 
 
 6.5 
 
 6.0 
 
 5.5 
 
 4.5 
 
 4.5 
 
 4.0 
 
 4.0 
 
 3.5 
 
 3.5 
 
 3.0 
 
 3.0 
 
 5.5 
 
 5.0 
 
 4.5 
 
 4.0 
 
 4.0 
 
 3.5 
 
 3.5 
 
 3.0 
 
 3.0 
 
 2.5 
 
 2.5 
 
 5.5 
 
 5.0 
 
 4.5 
 
 4.0 
 
 4.0 
 
 3.5 
 
 3.5 
 
 3.0 
 
 3.0 
 
 2.5 
 
 2.5 
 
 5.0 
 
 4.5 
 
 4.0 
 
 3.5 
 
 3.5 
 
 3.0 
 
 3.0 
 
 2.5 
 
 2.5 
 
 2.5 
 
 2.0 
 
 5.0 
 
 4.5 
 
 4.0 
 
 3.5 
 
 3.5 
 
 3.0 
 
 3.0 
 
 2.5 
 
 2.5 
 
 2.5 
 
 2.0 
 
 4.5 
 
 4.0 
 
 3.5 
 
 3.0 
 
 3.0 
 
 3.0 
 
 2.5 
 
 2.5 
 
 2.0 
 
 2.0 
 
 2.0 
 
 4.5 
 
 4.0 
 
 3.5 
 
 3.0 
 
 3.0 
 
 3.0 
 
 2.5 
 
 2.5 
 
 2.0 
 
 2.0 
 
 2.0 
 
 4.0 
 
 3.5 
 
 3.0 
 
 2.5 
 
 2.5 
 
 2.5 
 
 2.0 
 
 2.0 
 
 2.0 
 
 2.0 
 
 1.5 
 
 3.5 
 
 3.0 
 
 3.0 
 
 2.5 
 
 2.5 
 
 2.0 
 
 2.0 
 
 2.0 
 
 1.5 
 
 1.5 
 
 1.5 
 
 3.0 
 
 3.0 
 
 2.5 
 
 2.5 
 
 2.0 
 
 2.0 
 
 2.0 
 
 1.5 
 
 1.5 
 
 1.5 
 
 1.5 
 
 3.0 
 
 2.5 
 
 2.5 
 
 2.0 
 
 2.0 
 
 2.0 
 
 1.5 
 
 1.5 
 
 1.5 
 
 1.5 
 
 1.5 
 
 2.5 
 
 2.5 
 
 2.0 
 
 2.0 
 
 1.5 
 
 1.5 
 
 1.5 
 
 1.5 
 
 1.5 
 
 
 
 2.5 
 
 2.0 
 
 2.0 
 
 .1.5 
 
 1.5 
 
 1.5 
 
 1.5 
 
 
 
 
 
 2.0 
 
 2.0 
 
 1.5 
 
 1.5 
 
 1.5 
 
 1.5 
 
 
 
 
 
 
 
 
 
 
 
 
 I 
 
 
 1 
 
 
 
 SAFE WORKING LOADS FOR HASONRY. 
 
 BRICK MASONRY IN WALLS OR PIERS. 
 
 Tons per sq. ft. 
 
 Hard brick in lime mortar. 5 to 7 
 
 Hard brick in Rosendale cement 1 to 3 ... 8 to 10 
 
60 MASONRY CONSTRUCTION 
 
 Tons per sq. ft. 
 
 Pressed brick in lime mortar 6 to 8 
 
 Pressed brick in Rosendale cement 9 to 12 
 
 Pressed brick in Portland cement 12 to 15 
 
 Piers exceeding in height six times their least dimension should 
 be increased 4 inches in size for each additional 6 feet. 
 
 According to the New York building laws, brickwork in good 
 lime mortar 8 tons per sq. ft., 11J tons when good lime and cement 
 mortar is used, and 15 tons when good cement mortar is used. ' 
 
 According to the Boston building laws: 
 
 Best hard-burned brick (height less than six times least dimen- 
 sion) with 
 
 Lb. per sq. ft. 
 
 Mortar, 1 cement, 2 sand 30,000 
 
 Mortar, 1 cement, 1 lime, 3 sand 24,000 
 
 Mortar, lime . 16,000 
 
 Best hard-turned brick (height six to twelve times least dimen- 
 sion) with 
 
 Mortar, 1 cement, 2 sand. 26,000 
 
 Mortar, 1 cement, 1 lime, 3 sand 20,000 
 
 Mortar, lime 14,000 
 
 For light hard-burned brick use f the above amounts. 
 
 STONE MASONRY. 
 
 Tons per sq. ft. 
 
 Rubble walls, irregular stone 3 
 
 Rubble walls, coursed, soft stone 2J 
 
 Rubble walls, coursed, hard stone 5 to 16 
 
 Dimension stone in cement: 
 
 Sandstone and limestone 10 to 20 
 
 Granite 20 to 40 
 
 Dressed stone, with f-inch dressed joints, in cement: 
 
 Granite 60 
 
 Marble or limestone 40 
 
 Sandstone 30 
 
 Height of columns not to exceed eight times least diameter. 
 MORTARS. 
 
 In i inch joints 3 months old: Tons per sq. ft. 
 
 Portland cement 1 to 4. . 40 
 
MASONRY CONSTRUCTION 61 
 
 Tons per sq. ft. 
 
 Rosendale cement 1 to 3 13 
 
 Lime mortar 8 to 10 
 
 Portland 1 to 2 in |-inch joints for bedding iron plates 70 
 
 CONCRETE. 
 
 Tons per sq. ft. 
 
 Portland cement 1 to S 8 to 20 
 
 Rosendale cement 1 to 6 , 5 to 10 
 
 Lime, best, 1 to 6 5 
 
 HOLLOW TILE. 
 
 Pounds per sq. ft. 
 
 Hard fire-clay tiles 80 
 
 Hard ordinary clay tiles GO 
 
 Porous terra-cotta tiles 40 
 
 Terra-cotta blocks, unfilled 10,000 
 
 Terra-cotta blocks, filled solid with brick or cement 20,000 
 
CHICAGO CLUB, FORMERLY THE ART INSTITUTE OF CHICAGO 
 
 Burnham & Root, Architects. 
 Exterior of Brovvnstone. Built in 1888. 
 
MASONRY CONSTRUCTION. 
 
 v.' 
 
 PART II. 
 
 CLASSIFICATION OF HASONRY. 
 
 Masonry is classified according to the nature of the material used, 
 as " stone masonry," "brick masonry," "mixed masonry," composed 
 of stones and bricks, and " concrete masonry." 
 
 Stone masonry is classified (1) according to the manner in which 
 the material is prepared, as "rubble masonry," "squared stone ma- 
 sonry," "ashlar masonry," "broken ashlar," and the combinations 
 of these four kinds; and (2) according to the manner in which the 
 work is executed, as "uncoursed rubble," "coursed rubble," "dry 
 rubble," "regular-coursed ashlar,"' 'broken or irregular-coursed 
 ashlar," "ranged work," "random ranged," etc. 
 
 DEFINITIONS OF THE TERMS USED IN MASONRY. 
 
 Abutment: (1) That portion of the masonry of a bridge or 
 dam upon which the ends rest, and which connects the superstruc- 
 ture with the adjacent banks. ' (2) A structure that receives the 
 lateral thrust of an arch. 
 
 Arris: The external angle or edge formed by the meeting of 
 two plane or curved surfaces, whether walls or the sides of a stick 
 or stone. 
 
 Backed : Built on the rear face. 
 
 Backing : The rough masonry of a wall faced with cut stone. 
 
 Batter : The slope or inclination given to the face of a wall. 
 It is expressed by dividing the height by the horizontal distance. It 
 is described by stating the extent of the deviation from the vertical, 
 as one in twelve, or one inch to the foot. 
 
 Bats : Broken bricks. 
 
 Bearing Blocks or Templets : Small blocks of stone built 
 in the wall to support the ends of particular beams. 
 
64 MASONRY CONSTRUCTION 
 
 Belt Stones or Courses : Horizontal bands or zones of stone 
 encircling a building or extending through a wall. 
 
 Blocking Course : A course of stone placed on the top of a 
 cornice, crowning the walls. 
 
 Bond: The disposing of the blocks of stone or bricks in the 
 walls so as to form the whole into a firm structure by a judicious over- 
 , lapping of each other so as to break joint. 
 
 A stone or brick which is laid with its length across the wall, or 
 extends through the facing course into that behind, so as to bind the 
 facing to the backing, is called a "Loader" or "bond." Bonds are 
 described by various names, as: 
 
 Binders, when they extend only a part of the distance across 
 the wall. 
 
 Through Bonds, when they extend clear across from face to back. 
 
 Heart Bonds, when two headers meet in the middle of the wall 
 and the joint between them is covered by another header. 
 
 Perpend Bond signifies that a header extends through the whole 
 thickness of the wall. . 
 
 Chain Bond is the building into the masonry of an iron bar, 
 chain, or heavy timber. 
 
 Cross Bond, in which the joints of the second stretcher course 
 come in the middle of the first; a course composed of headers and 
 stretchers intervening. 
 
 Block and Cross Bond, when the face of the wall is put up in cross 
 bond and the backing in block bond. 
 
 English Bond (brick masonry) consists of alternate courses of 
 headers and stretchers. 
 
 Flemish Bond (brick masonry) consists of alternate headers and 
 stretchers in the same course. 
 
 Blind Bond is used to tie the front course to the wall in pressed 
 brick work where it is not desirable that any headers should be seen 
 in the face work. 
 
 To form this bond the face brick is trimmed or clipped off at 
 both ends, so that it will admit a binder to set in transversely from 
 the face of the wall, and every layer of these binders should be tied 
 with a header course the whole length of the wall. The binder should 
 be put in every fifth course, and the backing should be done in a most 
 substantial manner, with hard brick laid in close joints, for the reason 
 
MASONRY CONSTRUCTION 65 
 
 that the face work is laid in a fine putty mortar, and the joints con- 
 sequently close and tight; and if the backing is not the same the 
 pressure upon the wall will make it settle and draw the wall inward. 
 The common form of bond in brickwork is to lay three or five courses 
 as stretchers, then a header course. 
 
 Breast Wall : One built to prevent the falling of a vertical 
 face cut into the natural soil; in distinction to a retaining wall, etc. 
 
 Brick Ashlar : Walls with ashlar facing backed with bricks. 
 
 Build or Rise : That dimension of the stone which is per- 
 pendicular to the quarry bed. 
 
 Buttress : A vertical projecting piece of stone or brick masonry 
 built in front of a wall to strengthen it, 
 
 Closers are pieces of brick or stone inserted in alternate courses 
 of brick and broken ashlar masonry to obtain a bond. 
 
 Cleaning Down consists in washing and scrubbing the stone- 
 work with muriatic acid and water. Wire brushes are generally 
 used for marble and sometimes for sandstone. Stiff bristle brushes 
 are ordinarily used. The stones should be scrubbed until all mortar 
 stains and dirt are entirely removed. 
 
 For cleaning old stonework the sand blast operated either by 
 steam or compressed air is used. Brick masonry is cleaned in the 
 same manner as stone masonry. During the process of cleaning all 
 open joints under window sills and elsewhere should be pointed. 
 
 Coping : The coping of a wall consists of large and heavy 
 stones, slightly projecting over it at both sides, accurately bedded on 
 the wall, and jointed to each other with cement mortar. Its use is 
 to shelter the mortar in the interior of the wall from the weather, and 
 to protect by its weight the smaller stones below it from being knocked 
 off or picked out. Coping stones should be so shaped that water 
 may rapidly run off from them. 
 
 For coping stones the objections with regard to excess of length 
 do not apply; this excess may, on the contrary, prove favorable, 
 because, the number of top joints being thus diminished, the mass 
 beneath the coping will be better protected. 
 
 Additional stability is given to a coping by so connecting the 
 coping stones together that it is impossible to lift one of them without 
 at the same time lifting the ends of the two next it. This is done 
 either by means of iron cramps inserted into holes in the stone and 
 
MASONRY CONSTRUCTK )X 
 
 fixed there with lead, or, better still, by means of dowels of wrought 
 iron, cast iron, copper, or hard stone. The metal dowels are inferior 
 in durability to those of hard stone, though superior in strength. 
 Copper is strong and durable, but expensive. The stone dowels are 
 small prismatic or cylindrical blocks, each of which fits into a pair 
 of opposite holes in the contiguous ends of a pair of coping stones 
 and fixed with cement mortar. 
 
 The under edge should be throated or dipped, that is, grooved, 
 so that the drip will not run back on the wall, but dror> from the edge. 
 Coping is divided into three kinds. 
 
 Parallel coping, level on top. Feather-edged coping, bedded 
 level and sloping on top. SaddMxick copnuj lias a curved or doubly 
 inclined top. 
 
 Corbell : A horizontal projecting' piece, or course, of inasonrv 
 which assists in supporting one resting upon it which projects still 
 further. 
 
 Cornice : The ornamental projection at the eaves of a building 
 or at the top of a pier or any other structure. 
 
 Counterfort: Vertical projections of stone or brick masonry 
 built at intervals along the back of a wall to strengthen it, and gen- 
 erally of very little use. 
 
 Course: The term course is applied to each horizontal row or 
 layer of stones or bricks in a wall; some of the courses have particular 
 names, as: 
 
 Plinth Course, a lower, projecting, square-faced course; also 
 called the water table. 
 
 Blocking Course, laid on top of the cornice. 
 
 Bonding Course, one in which the stones or bricks lie with their 
 length across the wall; also called heading course. 
 
 Stretching Course, consisting of stretchers. 
 
 Springing Course, the course from which an arch springs. 
 
 String Course, a projecting course. 
 
 Rowlock Course, bricks set on edge. 
 
 Cramps : Bars of iron having the ends turned at right angles 
 to the- body of the bar, and inserted in holes and trenches 
 cut in the upper sides of adjacent stones to hold them together 
 (see Coping). 
 
HOUSE IN WASHINGTON, D. C. 
 
 Wood, Donn & Deming, Architects, Washington, D. C. 
 
 Doric Colonial Front. 
 
MASONRY CONSTRUCTION 67 
 
 Cutwater or Starling : The projecting ends of a bridge- 
 pier, etc., usually so shaped as to allow water, ice, etc., to strike them 
 with but little injury. 
 
 Dowels : Straight bars of iron, copper, or stone, which are 
 placed in holes cut in the upper bed of one stone and in the lower bed 
 of the next stone above. They are also placed horizontally in the 
 adjacent ends of coping stones (see under Coping). Cramps arfd 
 dowels are fastened in place by pouring melted lead, sulphur, or 
 cement grout around them. 
 
 Dry Stone Walls may be of any of the classes of masonry 
 previously described, with the single exception that the mortar is 
 omitted. They should be built according to the principles laid down 
 for the class to which they belong. 
 
 Face : The front surface of the wall. 
 
 Facing : The stone which forms the face or outside of the wall 
 exposed to view. 
 
 Footing : The projecting courses at the base of a wall for the 
 purpose of distributing the weight over an increased area, and thereby 
 diminishing the liability to vertical settlement from compression of 
 the ground. 
 
 Footings, to have any useful effect, must be securely bonded 
 into the body of the work, and have sufficient strength to resist the 
 cross strains to which they are exposed. The beds should be dressed 
 true and parallel. Too much care cannot be bestowed upon the 
 footing courses of any building, as upon them depends much of the 
 stability of the work. If the bottom course be not solidly bedded, 
 if any rents or vacuities are left in the beds of the masonry, or if the 
 materials be unsound or badly put together, the effects of such care- 
 lessness will show themselves sooner or later, and always at a period 
 when remedial efforts are useless. 
 
 Gauged Work : Bricks cut and rubbed to the exact shape 
 required. 
 
 Grout is a thin or fluid mortar made in the proportion of 1 of 
 cement to 1 or 2 of sand. It is used to fill up the voids in walls of 
 rubble masonry and brick. Sometimes the interior of a wall is built 
 up dry and grout poured in to fill the voids. Unless specifically 
 instructed to permit its use, grout should not be used unless in the 
 presence of the inspector. When used by masons without instruc- 
 
68 MASONRY CONSTRUCTION 
 
 tions it is usually for the purpose of concealing bad work, (irout is 
 used for solidifying quicksand. 
 
 Grouting is pouring fluid mcrtar over last course for the purpose 
 of filling all vacuities. 
 
 Header. Also called a bond. A stone or brick whose greatest 
 dimension lies perpendicular to the face of the wall, and used for the 
 purpose of tying the face to the backing (see Bond). A trick of 
 masons is to use "blind headers," or short stones that look like 
 headers on the face, but do not go deeper into the wall than the 
 adjacent stretchers. When a course has been put on top of these 
 they are completely covered up, and, if not suspected, the fraud will 
 never be discovered unless the weakness of the wall reveals it. 
 
 In facing brick walls with pressed brick the bricklayer will fre- 
 quently cut the headers for the purpose of economizing the more expen- 
 sive material ; thus great watchfulness is necessary to secure a good bond 
 between the facing and common brick. "All stone foundation walls 
 21 inches or less in thickness shall have at least one header extending 
 through the wall in every 3 feet in height from the bottom of the wall, and 
 in every 3 feet in length, and if over 24 inches in thickness shall have one 
 header for every 6 superficial feet on both sides of the wall, and fun- 
 ning into the wall at least 2 feet. All headers shall be at least ] 2 inches 
 in width and 8 inches in thickness, and consist of good, flat stone. 
 
 " In all brick walls every sixth course shall be a heading course, 
 except where walls are faced with brick in running bond, in which 
 latter case every sixth course shall be bonded into the backing by 
 cutting the course of the face brick and putting in diagonal headers 
 behind the same, or by splitting the face brick in half and backing 
 the same with a continuous row of headers." 
 
 Joints, The mortar layers between the stone or bricks are 
 called the joints. The horizontal joints are called "bed joints;" the 
 end joints are called the vertical joints, or simply the "joints." 
 
 Excessively thick joints should be avoided. In good brickwork 
 they should be about J to J inch thick; for ashlar masonry and pressed 
 brickwork, about J to -^ inch thick; for rubble masonry they vary 
 according to the character of the work. 
 
 The joints of both stone and brick masonry are finished in 
 different ways, with the object of presenting a neat appearance and 
 of throwing the rainwater away from the joint. 
 
MASONRY CONSTRUCTION 69 
 
 Flush Joints. In these the mortar is pressed flat with the trowel 
 and the surface of the joint is flush with the face of the wall. 
 
 Struck Joints are formed by pressing or striking back with the 
 trowel the upper portion of the joint while the mortar is moist, so as 
 to form, an outward sloping surface from the bottom of the upper 
 course to the top of the lower course. This joint is also designated 
 by the name " weather joint." Masons generally form this joint so 
 that it slopes inwards, thus leaving the upper arris of the lower course 
 bare and -exposed to the action of the weather. The reason for form- 
 ing it in this improper manner is that it is easier to perform. 
 
 Key Joints are formed by drawing a curved iron key or jointer 
 along the center of the flushed joint, pressing it hard, so that the 
 mortar is driven in beyond the face of the wall; a groove of curved 
 section is thus formed, having its surface hardened by the pressure. 
 
 White Skate or Groove Joint is employed in front brickwork. It 
 is about -j^ -inch thick. It is formed with a jointer having the width 
 of the intended joint. It is guided along the joint by a straight edge 
 and leaves its impress upon the material. 
 
 Joggle : A joint piece or dowel pin let into adjacent faces of 
 two stones to hold, them in position. It may vary in form and ap- 
 proach in its shape either the dowel or clamp. 
 
 Jamb : The sides of an opening left in a wall. 
 
 Lintel : The stone, wood, or iron beam .used to cover a narrow 
 opening in a wall. 
 
 One=Man Stone : A stone of such size as to be readily lifted 
 by one man. 
 
 Parapet Wall is a low wall running along the edge of a terrace 
 or roof to prevent people from falling over. 
 
 Pointing a piece of masonry consists in scraping out the mortar 
 in which the stones were laid from the face of the joints for a depth 
 of from J to 2 inches, and filling the groove so made with clear Port- 
 land-cement mortar, or with mortar made of 1 part of cement and 
 1 part of sand. 
 
 The object of pointing is that the exposed edges of the joints 
 are always deficient in density and hardness, and the mortar near the 
 surface of the joint is specially subject to dislodgment, since the con- 
 traction and expansion of the masonry are liable either to separate 
 the stone from the mortar or to crack the mortar in the joint, thus 
 
70 MASONRY CONSTRUCTION 
 
 permitting the entrance of rainwater, which freezing forces the mortar 
 from the joints. 
 
 The pointing mortar, when ready for use, should be rather inco- 
 herent and quite deficient in plasticity. 
 
 Before applying the pointing, the joint must be well cleansed by 
 scraping and brushing .out the loose matter, then thoroughly saturated 
 with water, and maintained in such a condition of dampness that the 
 stones will neither absorb water from the mortar nor impart any to it. 
 Walls should not be allowed to dry too rapidly after pointing. 
 
 Pointing should not be prosecuted either during free/ing or 
 excessively hot weather. 
 
 The pointing mortar is applied with a mason's trowel, and the 
 joint well calked with a calking- iron and hammer. In the very best 
 work the surface of the mortar is rubbed smooth with a steel polishing 
 tool. The form given to the finish joint is the same as described 
 under joints. 
 
 Pointing with colored mortar is frequently employed to improve 
 the appearance of the work. Various colors are used, as white, black, 
 red, brown, etc., different colored pigments being added to the mortar 
 to produce the required color. 
 
 Tuck Pointing, used chiefly for brickwork, consists of a project- 
 ing ridge with the edges neatly pared to an uniform breadth of about 
 i-inch. White mortar is usually employed for this class of pointing. 
 
 Many authorities consider that pointing is not advisable for new 
 work, as the joints so formed are not as enduring as those which are 
 finished at the time the masonry is built. Pointing is, moreover, 
 often resorted to when it is intended to give the work a superior 
 appearance, and also to conceal defects in inferior work. 
 
 Pallets, Plugs : Wooden bricks inserted in walls for fastening 
 trim, etc. 
 
 Plinth : A projecting base to a wall; also called "water table." 
 
 Pitched- Face Masonry : That in which the face of the stone 
 is roughly dressed with the pitching chisel so as to give edges that are 
 approximately true. 
 
 Quarry-Faced or Rock-Faced Masonry : That in which the 
 face of the stone is left untouched as it comes from the quarry. 
 
 Quoin : A cornerstone. A quoin is a header for one face and 
 a stretcher for the other. 
 
MASONRY CONSTRUCTION 71 
 
 Rip=Rap. Rip-rap is composed of rough undressed stone.as it 
 comes from the quarry, laid dry about the base of piers, abutments, 
 slopes of embankments, etc., to prevent scour and wash. When 
 used for the protection of piers the stones are dumped in promis- 
 cuously, their size depending upon the material and the velocity of 
 the current. Stones of 15 to 25 cubic feet are frequently employed. 
 When used for the protection of banks the stones are laid by hand 
 to a uniform thickness. 
 
 Rise : That dimension of a stone which is perpendicular to its 
 quarry bed (see Build). 
 
 Retaining Wall or Revetment t A wall built to retain eartJ 
 deposited behind it (see Breast Wall). 
 
 Reveal : The exposed portion of the sides of openings in walk 
 in front of the recesses for doors, window frames, etc. 
 
 Slope=Wall Masonry : A slope wall is a thin layer of masonry 
 used to protect the slopes of embankments, excavations, canals, river 
 banks, etc., from rain, waves, weather, etc. 
 
 Slips : See Wood Bricks. 
 
 Spall : A piece of stone chipped off by the stroke of a hammer. 
 
 Sill ; The stone, iron, or wood on which the window or doo* 
 of a building rests. In setting stone sills the mason beds the ends 
 only; the middle is pointed up after the building is enclosed. They 
 should be set perfectly level lengthwise, and have an inclination cross- 
 wise, so the water may flow from the frame. 
 
 Stone Paving consists of roughly squared or unsquared blocks 
 of stone used for paving the waterway of culverts, etc.; it is laid both 
 dry and in mortar. 
 
 Starling : See Cutwater. 
 
 Stretcher ; A stone or brick whose greatest dimension lies 
 parallel to the face of the wall. 
 
 String Course : A horizontal course of brick or stone masonry 
 projecting a little beyond the face of the wall. Usually introduced 
 for ornament. 
 
 Two=Men Stone : Stone of such size as to be conveniently 
 lifted by two men. 
 
 Toothing : Unfinished brickwork so arranged that every alter- 
 nate brick projects half its length. 
 
 Water-Table : See Plinth. 
 
72 MASONRY CONSTRUCTION 
 
 Wood Bricks, Pallets, Plugs, or Slips are pieces of wood 
 laid in a wall in order the better to secure any woodwork that it may 
 be necessary to fasten to it. Great injury is often done to walls by 
 driving wood plugs into the joints, as they are apt to shake the work. 
 Hollow porous terra-cotta bricks are frequently used instead of wood 
 bricks, etc. 
 
 PREPARATION OF THE MATERIALS. 
 STONE CUTTING. 
 
 Dressing the Stones, The stonecutter examines the rough 
 blocks as they come from the quarry in order to determine whether 
 the blocks will work to better advantage as a header, a stretcher, or a 
 cornerstone. Having decided for which purpose the stone is suited, 
 he prepares to dress the bottom bed. The stone is placed with bottom 
 bed up, all the rough projections are removed with the hammer and 
 pitching tool, and approximately straight lines are pitched off around 
 its edges; then a chisel draft is cut on all the edges. These drafts 
 are brought to the same plane as nearly as practicable by the use of 
 two straight edges having parallel sides and equal widths, and the 
 enclosed rough portion is then dressed down with the pitching tool 
 or point to the plane of the drafts. The entire bed is then pointed 
 down to a surface true to the straight edge when applied in any direc- 
 tion crosswise, lengthwise, and diagonally. 
 
 Lines are then marked on this dressed surface parallel and per- 
 pendicular to the face of the stone, enclosing as large a rectangle as 
 the stone will admit of being worked to, or of such dimensions as may 
 be directed by the plan. 
 
 The faces and sides are pitched off to these lines. A chisel draft 
 is then cut along all four edges of the face, and the face either 
 dressed as required, or left rock faced. The sides are then pointed 
 down to true surfaces at right angles to the bed. The stone is 
 turned over bottom bed down, and the top bed dressed in the same 
 manner as the bottom. It is important that the top bed be exactly 
 parallel to the bottom bed in order that the stone may be of uniform 
 thickness. 
 
 Stones having the beds inclined to each other, as skewbacks, or 
 stones having the sides inclined to the beds, are dressed by using a 
 bevelled straight edge set to the required inclination. 
 
MASONRY CONSTRUCTION 73 
 
 Arch stones have two plane surfaces inclined to each other; these 
 are called the beds. The upper surface or extrados is usually left 
 rough; the lower surface or intrados is cut to the curve of the arch. 
 This surface and the beds are cut true by the use of a wooden or 
 metal templet which is made according to the drawings furnished by 
 the engineer or architect. 
 
 TOOLS USED IN STONE CUTTING. 
 
 The Double=Face Hammer is a heavy tool, weighing from 20 
 to 30 pounds, used for roughly shaping stones as they come from the 
 quarry and for knocking off projections. This is used for only the 
 roughest work. 
 
 The Face Hammer has one blunt and one cutting end, and is 
 used for the same purpose as the double-face hammer where less 
 weight is required. The cutting end is used for roughly squaring 
 stones preparatory to the use of the finer tools. 
 
 The Cavil has one blunt and one pyramidal or pointed end, 
 and weighs from 15 to 20 pounds. It is used in quarries for roughly 
 shaping stone for transportation. 
 
 The Pick somewhat resembles the pick used in digging, and is 
 used for rough dressing, mostly on limestone and sandstone. Its 
 length varies from 15 to 24 inches, the thickness at the eye being 
 about 2 inches. 
 
 The Axe or Pean Hammer has two opposite cutting edges. 
 It is used for making drafts around the arris or edge of stones, and in 
 reducing faces, and sometimes joints, to a level. Its length is about 
 10 inches and the cutting edge about 4 inches. It is used after the 
 point and before the patent hammer. 
 
 The Tooth Axe is like the axe, except that its cutting edges 
 are divided into teeth, the number of which varies with the kind of 
 work required. This tool is not used in cutting granite or gneiss. 
 
 The Bush Hammer is a square prism of steel, whose ends are 
 cut into a number of pyramidal points. The length of the hammer 
 is from 4 to 8 inches and the cutting face from 2 to 4 inches square. 
 The points vary in number and in size with the work to be done. 
 One end is sometimes made with a cutting edge like that- of the axe. 
 
 The Crandall is a malleable-iron bar about 2 feet long slightly 
 flattened at one end. In this end is a slot 3 inches long and jj-inch 
 
74 MASONRY CONSTRUCTION 
 
 wide. Through this slot are passed ten double-headed points of 
 J-inch square steel 9 inches long, which are held in place by a key. 
 
 The Patent Hammer is a double-headed tool so formed as to 
 hold at each end a set of wide thin chisels. The tool is in two parts, 
 which are held together by the bolts which hold the chisels. Lateral 
 motion is prevented by four guards on one of the pieces. The tool 
 without the teeth is 5J X 2f X 1^ inches. The teeth are 2} inches 
 wide; their thickness varies from T y to ^ of an inch. This tool is used 
 for giving a finish to the surface of stones. 
 
 The Hand Hammer, weighing from 2 to 5 pounds, is used in 
 drilling holes and in pointing and chiselling the harder rocks. 
 
 The Mallet is used where the softer limestones and sandstones 
 are cut. 
 
 The Pitching Chisel is usually of IJ-inch octagonal steel, 
 spread on the cutting edge to a rectangle of J X 2^ inches. It is used 
 to make a well-defined edge to the face of a stone, a line being marked 
 on the joint surface, to which the chisel is applied and the portion of 
 the stone outside of the line broken off by a blow with the hand ham- 
 mer on the head of the chisel. 
 
 The Point is made of round or octagonal steel from J to 1 inch in 
 diameter. It is made about 12 inches long, with one end brought to 
 a point. It is used until its length is reduced to about 5 inches. It 
 is employed for dressing off the irregular surface of stones, either for 
 a permanent finish or preparatory to the use of the axe. According 
 to the hardness of the stone, either the hand hammer or the mallet 
 is used with it. 
 
 The Chisel is of round steel of J to f-inch diameter and about 
 10 inches long, with one end brought to a cutting edge from J inch 
 to 2 inches wide; is used for cutting drafts or margins on the face of 
 stones. 
 
 The Tooth Chisel is the same as the chisel, except that the 
 cutting edge is divided into teeth. It is used only on marbles and 
 sandstones. 
 
 The Splitting Chisel is used chiefly on the softer stratified 
 stones, and sometimes on fine architectural carvings in granite. 
 
 The Plug, a truncated wedge of steel, and the feathers of half- 
 round malleable iron, are used for splitting unstratified stone. A 
 row of holes is made with the drill on the line on which the fracture 
 
MASONRY CONSTRUCTION 75 
 
 is to be made; in each of these two feathers are inserted, and the plugs 
 lightly driven in between them. The plugs are then gradually driven 
 home by light blows of the hand hammer on each in succession until 
 the stone splits. 
 
 Machine Tools. In all large stone yards machines are used 
 to prepare the stone. There is a great variety in their form, but 
 since the kind of dressing never takes its name from the machine 
 which forms it,. it will be neither necessary nor profitable to attempt 
 a description of individual machines. They include stone saws, 
 stone cutters, stone grinders, stone p'olishers, etc. 
 
 DEFINITION OF TERMS USED IN STONE CUTTING. 
 
 Axed : Dressed to a plane surface with an axe. 
 
 Boasted or Chiselled : Having face wrought with a chisel or 
 narrow tool. 
 
 Broached: Dressed with a " punch" after being droved. 
 
 Bush Hammered : Dressed with a bush hammer. 
 
 Crandalled : Wrought to a plane with a crandall. 
 
 Deadening : The crushing or crumbling of a soft stone under 
 the tools while being dressed. 
 
 Dressed Work: That which is' wrought on the face; also 
 applied to stones having the joints wrought to a plane surface, but 
 not " squared." 
 
 Drafted : Having a narrow chisel draft cut around the face 
 or margin. 
 
 Droved, Stroked : Wrought with a broad chisel or hammer 
 in parallel flutings across the stone from end to end. 
 
 Hammer Dressed : Worked with the hammer. 
 
 Herring Bone : Dressed in angular flutings. 
 
 Nigged or Nidged : Picked with a pointed hammer or cavil 
 to the desired form. 
 
 Patent Hammered : Dressed with a patent hammer. 
 
 Picked : Reduced to an approximate plane with a pick. 
 
 Pitched : Dressed to the neat lines or edges with a pitching 
 chisel. 
 
 Plain : Rubbed smooth to remove tool marks. 
 
 Pointed : Dressed with a point or very narrow tool. 
 
 Polished : Rubbed down to a reflecting surface. 
 
76 MASONRY CONSTRUCTION 
 
 Prison : Having surfaces wrought into holes. 
 
 Random Tooled or Droved: Cut with a broad tool into 
 irre'gular flutings. 
 
 Rock Faced, Quarry Faced, Rough : Left as it comes from 
 the quarry. It may be drafted or pitched to reduce projecting points 
 on the face to give limits. 
 
 Rubbed : See Plain. 
 
 Rustic, Rusticated : Having the faces of stones projecting 
 beyond the arrises, which are bevelled or drafted. The face may be 
 dressed in any desired manner. 
 
 Scabble : To dress off the angular projections of stones for 
 rubble masonry with a stone axe or hammer. 
 
 Smooth : See Plain. 
 
 Square Droved : Having the flutings perpendicular to the 
 lower edge of the stone. 
 
 Striped : Wrought into parallel grooves with a point or punch. 
 
 Stroked: See Droved. 
 
 Tooled : Wrought to a plane with an inch tool. See Droved. 
 
 Toothed : Dressed with a tooth chisel. 
 
 Vermiculated Worm Work: Wrought into veins by cutting 
 away portions of the face. 
 
 METHODS OF FINISHING THE FACES OF CUT STONE, 
 
 In architecture there are a great many ways in which the faces 
 of cut stone may be dressed, but the following are those that will be 
 usually met in engineering work. 
 
 Rough Pointed. W T hen it is necessary to remove an inch or 
 more from the face of a stone it is done by the pick or heavy point 
 until the projections vary from -J- to 1 inch. The stone is said to be 
 rough pointed. In dressing limestone and granite this operation 
 precedes all others. 
 
 Fine Pointed. If a smoother finish is deshed rough pointing 
 is followed by fine pointing, which is done with a fine point. Fine 
 pointing is used only where the finish made by it is to be final, and 
 never as a preparation for a final finish by another tool. 
 
 Crandalled. This is only a speedy method of pointing, the 
 effect being the same as fine pointing, except that the dots on the 
 stone are more regular. The variations of level are about J inch and 
 
MASONRY CONSTRUCTION 
 
 77 
 
 the rows are made parallel. When other rows at right angles to the 
 first are introduced the stone is said to be cross-crandalled. 
 
 Axed or Pean Hammered, and Patent Hammered. These 
 two vary only in the degree of smoothness of the surface which is 
 produced. The number of blades in a patent hammer varies from 
 6 to 12 to the inch; and in precise specifications the number of cuts 
 to the inch must be stated, such as 6-cut, 8-cut, 10-cut, 12-cut. The 
 
 Pointed 
 
 Fine Pointed 
 
 B us/7-/! 0/77/77 erect 
 
 Pafent-h am m ere d 
 
 Cro>r>da//ed Rock-face with Draff Line 
 
 Fig. 19. Methods of Finishing the Faces of Cut Stone. 
 
 effect of axing is to cover the surface with chisel marks, which are 
 made parallel as far as practicable. Axing is a final finish. 
 
 Tooth Axed. The tooth axe is practically a number of points, 
 and it leaves the surface of a stone in the same condition as fine 
 pointing. It is usually, however, only a preparation for bush ham- 
 mering, and the work is then done without regard to effect, so long 
 as the surface of the stone is sufficiently levelled. 
 
78 MASONRY CONSTRUCTION 
 
 Bush Hammered. The roughnesses of a stone are pounded 
 off by the bush hammer, and the stone is then said to be "bushed." 
 This kind of finish is dangerous on sandstone, as experience has 
 shown that sandstone thus treated is very apt to scale. In dressing 
 limestone which is to have a bush hammered finish the usual sequence 
 of operation is (1) rough pointing, (2) tooth axing, and (3) bush 
 hammering. 
 
 CLASSIFICATION OF THE STONES. 
 
 All the stones used in building are divided into three classes 
 according to the finish of the surface, viz.: 1. Rough stones that 
 are used as they come from the quarry. 2. Stones roughly squared 
 and dressed. 3.' Stones accurately squared and finely dressed. 
 
 Unsquared Stones. This class covers all stones which are 
 used as they come from the quarry without other preparation than 
 the removal of very acute angles and excessive projections from the 
 general figure. 
 
 Squared Stones. This class covers all stones that are roughly 
 squared and roughly dressed on beds and joints. The dressing is 
 usually done with the face hammer or axe, or in soft stones with the 
 tooth hammer. In gneiss, hard limestones, etc., it may be necessary 
 to use the point. The distinction between this class and the third 
 lies in the degree of closeness of the joints. Where the dressing on 
 the joints is such that the distance between the general planes of the 
 surfaces of adjoining stones is one-half inch or more, the stones prop- 
 erly belong to this class. 
 
 Three subdivisions of this class may be made, depending on the 
 character of the face of the stones. 
 
 (a) Quarry-faced or Rock-faced stones are those whose faces are 
 left untouched as they come from the quarry. 
 
 (b) Pitched-faced stones are those on which the arris is clearly 
 defined by a line beyond which the rock is cut away by the pitching 
 chisel, so as to give edges that are approximately true. 
 
 (c) Drafted stones are those on which the face is surrounded by a 
 chisel draft, the space inside the draft being left rough. ( )rdinarily, 
 however, this is done only on stones in which the cutting of the joints 
 is such as to exclude them from this class. 
 
 In ordering stones of this class the specifications should always 
 state the width of the bed and end joints which are expected, and also 
 
MASONRY CONSTRUCTION 79 
 
 how far the surface of the face may project beyond the plane of the 
 edge. In practice the projection varies between 1 inch and 6 inches. 
 It should also be specified whether or not the faces are to be drafted. 
 Cut Stones. This class covers all squared stones with smoothly 
 dressed beds and joints. As a rule, all the edges of cut stones are 
 drafted, and between the drafts the stone is smoothly dressed. The 
 face, however, is often left rough where construction is massive. 
 The stones of this class are frequently termed " dimension" stone or 
 "dimension" work. 
 
 ASHLAR MASONRY. 
 
 Ashlar masonry consists of blocks of stone cut to regular figures, 
 generally rectangular, and built in courses of uniform height or rise, 
 which is seldom less than a foot. 
 
 Size of the Stones. In order that the stones may not be 
 liable to be broken across, no stone of a soft material, such as the 
 weaker kinds of sandstone and granular limestone, should have a 
 length greater than 3 times its depth or rise; in harder materials the 
 length may be 4 to 5 times the depth. The breadth in soft materials, 
 may range from 1J to double the depth; in hard materials it may be 
 3 times the depth. 
 
 Laying the Stone. The bed on which the stone is to be laid 
 should be thoroughly cleansed from dust and well moistened with 
 water. A thin bed of mortar should then be spread evenly over it, 
 and the stone, the lower bed of which has been cleaned and moistened, 
 raised into position, and lowered first upon one or two strips of wood 
 laid upon the mortar bed; then, by the aid 'of the pinch bar, moved 
 exactly into its place, truly plumbed, the strips of wood removed, 
 and the stone settled in its place and levelled by striking it with wooden 
 mallets. In using bars and rollers in handling cut stone, the mason 
 must be careful to protect the stone from injury by a piece of old 
 bagging, carpet, etc. 
 
 In laying "rock-faced" work, the line should be carried above 
 it, and care must be taken that the work is kept plumb with the cut 
 margins of the corners and angles. 
 
 The Thickness of Mortar in the joints of well executed 
 ashlar masonry should be about J- of an inch, but it is usually about f . 
 
 Amount of Mortar. The amount of mortar required for 
 ashlar masonry varies with the size of the blocks, and also with 
 
80 MASONRY CONSTRUCTION 
 
 the closeness of the dressing. With f to J-mch joints and 12 to 
 20-inch courses will be about 2 cubic feet of mortar per cubic yard; 
 with larger blocks and closer joints, there will be about 1 cubic foot 
 of mortar per yard of masonry. Laid in 1 to 2 mortar, ordinary 
 ashlar will require J to J of a barrel of cement per cubic yard of 
 masonry. 
 
 Bond of Ashlar Masonry. No side joint in any course 
 should be directly above a side joint in the course below; but the 
 stones should overlap or break joint to an extent of from once to once 
 and a half the depth or rise of the course. This is called the bond of 
 the masonry; its effect is to cause each stone to be supported by at 
 least two stones of the course below, and assist in supporting at least 
 two stones of the course above; and its objects are twofold: first, to 
 distribute the pressure, so that inequalities of load on the upper part 
 of the structure, or of resistance at the foundation, may be transmit- 
 ted to and spread over an increasing area of bed in proceeding down- 
 wards or upwards, as the case may be; and second, to tie the structure 
 together, or give it a sort of tenacity, both lengthwise and from face 
 to back, by means of the friction of the stones where they overlap. 
 The strongest bond in ashlar masonry is that in which each course 
 at the face of the wall contains a header and a stretcher alternately, 
 the outer end of each header resting on the middle of a stretcher of 
 the course below, so that rather more than one-third of the area of 
 the face consists of ends of headers. This proportion may be devi- 
 ated from when circumstances require it; but in every case it is ad- 
 visable that the ends of headers should not form less than one-fourth 
 of the whole area of the face of the wall. 
 
 SQUARED=STONE HASONRY. 
 
 The distinction between squared-stone masonry and ashlar lies 
 in the character of the dressing and the closeness of the joints. In 
 this class of masonry the stones are roughly squared and roughly 
 dressed on beds and joints, so that the width of the joints is half an 
 inch or more. The same rules apply to breaking joint, and to the 
 proportions which the lengths and breadths of the stones should bear 
 to their depths, as in ashlar; and as in ashlar, also, at least one-fourth 
 of the face should consist of headers, whose length should be from 
 three to five times the depth of the course. 
 
MASONRY CONSTRUCTION 81 
 
 Amount of Mortar. The amount of mortar required for 
 squared-stone masonry varies with the size of the stones and with the 
 quality of the masonry; as a rough average, one-sixth to one-quarter 
 of the mass is mortar. When laid in 1 to 2 mortar, from J to f of a 
 barrel of cement will be required per cubic yard of masonry. 
 
 BROKEN ASHLAR. 
 
 Broken ashlar consists of cut stones of unequal depths, laid in 
 the wall without any attempt at maintaining courses of equal rise, 
 or the stones in the same course of equal depth. The character of 
 the dressing and closeness of the joints may be the same as in ashlar 
 or squared-stone masonry, depending upon the quality desired. The 
 same rules apply to breaking joint, and to the proportions which the 
 lengths and breadths of the stones should bear to their depths, as in 
 ashlar; and as in ashlar, also, at least one-fourth of the face of the 
 wall should consist of headers. 
 
 Amount of Mortar. The amount of mortar required when 
 laid in 1 to 2 mortar, will be from f to 1 barrel per cubic yard of 
 masonry, depending upon the closeness of the joints. 
 
 RUBBLE MASONRY. 
 
 Masonry composed of unsquared stones is called rubble. This 
 class of masonry covers a wide range of construction, from the com- 
 monest kind of dry-stone work to a class of work composed of large 
 stones laid in mortar. It comprises two classes: (1) uncoursed rub- 
 ble, in which irregular-shaped stones are laid without any attempt 
 at regular courses, and (2) coursed rubble, in which the blocks of 
 unsquared stones are levelled off at specified heights to an approx- 
 imately horizontal surface. Coursed rubble is often built in random 
 courses; that is to say, each course rests on a plane bed, but is not 
 necessarily of the same depth or at the same level throughout, so 
 that the beds occasionally rise or fall by steps. Sometimes it is 
 required that the stone shall be roughly shaped with the hammer. 
 
 In building rubble masonry of any of the classes above men- 
 tioned the stone should be prepared by knocking off all the weak 
 angles of the block. It should be cleansed from dust, etc., and 
 moistened before being placed on its bed. Each stone should be 
 firmly imbedded in the mortar. Care should be taken not only that 
 
82 MASONRY CONSTRUCTION 
 
 each stone shall rest on its natural bed, but that the sides parallel to 
 that natural bed shall be the largest, so that the stone may lie flat, 
 and not be set on edge or on end. However small and irregular the 
 stones, care should be taken to break joints. Side joints should not 
 form an angle with the bed joint sharper than 60. The hollows or 
 interstices between the larger stones must be filled with smaller stones 
 and carefully bedded in mortar. 
 
 One-fourth part at least of the face of the wall should consist of 
 bond stones extending into the wall a length of at least 3 to 5 times 
 their depth, as in ashlar. 
 
 Amount of Mortar, If rubble masonry is composed of small 
 and irregular stones, about .-J of the mass will consist of mortar; if 
 the stones are larger and more regular J to J will be mortar. Laid 
 in 1 to 2 mortar, ordinary rubble requires from i to 1 barrel of cement 
 per cubic yard of masonry. 
 
 ASHLAR BACKED WITH RUBBLE. 
 
 In this class of masonry the stones of the ashlar face should have 
 their beds and joints accurately squared and dressed with the hammer 
 or the points, according to the quality desired, for a breadth of from 
 once to twice (or on an average, once and a half), the depth or rise 
 of the course, inwards from the face; but the backs of these stones 
 may be rough. The proportion and length of the headers should be 
 the same as in ashlar, and the "tails" of these headers, or parts which 
 extend into the rubble backing, may be left rough at the back and 
 sides; but their upper and lower beds should be hammer dressed to 
 the general plane of the beds of the course. These tails may taper 
 slightly in breadth, but should not taper in depth. 
 
 The rubble backing, built in the manner described under Rubble 
 Masonry, should be carried up at the same time with the face work, 
 and in courses of the same rise, the bed of each course being carefully 
 formed to the same plane with that of the facing. 
 
 GENERAL RULES FOR LAYING ALL CLASSES OF 
 STONE MASONRY. 
 
 1. Build the masonry, as far as possible, in a series of courses, 
 perpendicular, or as nearly so as possible, to the direction of the pres- 
 sure which they have to bear, and by breaking joints avoid all long 
 continuous joints parallel to that pressure. 
 
AS( )\ \\ V ( X INSTRUCTION 
 
 83 
 
 2. Use the largest stones for the foundation course. 
 
 3. Lay all stones which consist of layers in such a manner that 
 the principal pressure which they have to bear shall act in a direction 
 perpendicular, or as nearly so as possible, to the direction of the 
 layers. This is called laying the stone on its natural bed, and is of 
 primary importance for strength and durability. 
 
 4. Moisten the surface of dry and porous stones before bedding 
 them, in order that the mortar may not be dried too fast and reduced 
 
 
 Regular Coursed Ashlar. 
 
 Random Coursed Ashlar. 
 
 Rubble, Undressed, Laid at Random. 
 Fig. 20. 
 
 Random Rubble with Hammer- Dressed Joints and 
 no Spalls on Face. 
 
 Types of Masonry. 
 
 to powder by the stone absorbing its moisture. 
 
 5. Fill every part of every joint and all spaces between the 
 stones w T ith mortar, taking care at the same time that such spaces 
 shall be as small as possible. 
 
 6. The rougher the stones, the oetter the mortar should be. 
 The principal object of the mortar is to equalize the pressure; and 
 the more nearly the stones are dressed to closely fitting surfaces, the 
 less important is the mortar. Not infrequently this rule is exactly 
 reversed; i.e., the finer the dressing the better the quality of the 
 mortar used. 
 
84 MASONRY CONSTRUCTION 
 
 All projecting courses, siich as sills, lintels, etc., should be covered 
 with boards, bagging, etc., as the work progresses, to protect them 
 from injury and mortar stains. 
 
 When setting cut stone a pailful of clean water should be kept 
 at hand, and when any fresh mortar comes in contact with the face 
 of the work it should be immediately washed off. 
 
 GENERAL RULES FOR BUILDING BRICK MASONRY. 
 
 1. Reject all misshapen and unsound bricks. 
 
 2. Cleanse the surface of each brick, and wet it thoroughly 
 before laying it, in order that it may not absorb the moisture of the 
 mortar too quickly. 
 
 3. Place the beds of the courses perpendicular, or as nearly 
 perpendicular as possible, to the direction of the pressure which they 
 have to bear; and make the bricks in each course break joint with 
 those of the courses above and below by overlapping to the extent of 
 from one-quarter to one-half of the length of a brick. (For the style 
 of bond used in brick masonry, see under Bond in list of definitions.) 
 
 4. Fill every joint thoroughly with mortar. 
 
 Brick should not be merely laid, but every one should be rubbed 
 and pressed down in such a manner as to force the mortar into the 
 pores of the bricks and produce the maximum adhesion ; with quick- 
 setting cement, this is still more important than with lime mortar. 
 For the best work it is specified that the brick shall be laid with a 
 "shove joint," that .is, that the brick shall first be laid so as to project 
 over the one below, and be pressed into the mortar, and then be 
 shoved into its final position. 
 
 Bricks should be laid in full beds of mortar, filling end and side 
 joints in one operation. This operation is simple and easy with 
 skilful masons if they will do it -but it requires persistence to get 
 it accomplished. Masons have a habit of laying brick in a bed of 
 rnortar, leaving the vertical joints to take care of themselves, throwing 
 a little mortar over the top beds and giving a sweep with the trowel 
 which more or less disguises the open joint below. They also have 
 a way after mortar has been sufficiently applied to the top bed of 
 brick to draw the point of their trowel through it, making an open 
 channel with only a sharp ridge of mortar on each side (and generally 
 throwing some of it overboard), so that if the succeeding brick is 
 
MASONRY CONSTRUCTION 85 
 
 taken up it will show a clear hollow, free from mortar through the 
 bed. This enables them to bed the next brick with more facility 
 and avoid pressure upon it to obtain the requisite thickness of joint. 
 
 JL-UJLLIJLJL 
 
 J I 
 
 C 
 
 rpnpriri ~j_i 
 
 JLL 
 
 a 
 
 Common Bond. English Bond. Flemish Bond. 
 
 Fig. 21. Bond Used in Brick Masonry. 
 
 With ordinary interior work a common practice is to lay brick 
 with J and j-inch mortar joints; an inspector whose duty is to keep 
 joints down to J or f inch will not have an enviable task. 
 
 Neglect in wetting the brick before use is the cause of most of 
 the failures of brickwork. Bricks have a great avidity for water, and 
 if the mortar is stiff and the bricks dry, they will absorb the water 
 so rapidly that the mortar will not set properly, and will crumble in 
 the fingers when dry. Mortar is sometimes made so thin that the 
 brick will not absorb all the water. This practice is objectionable; 
 it interferes with the setting of the mortar, and particularly with the 
 adhesion of the mortar to the brick. Watery mortar also contracts 
 excessively in drying (if it ever does dry), which causes undue settle- 
 ment and, possibly, cracks or distortion. 
 
 The bricks should not be wetted to the point of saturation, or 
 they will be incapable of absorbing any of the moisture from the 
 mortar, and the adhesion between the brick and mortar will be weak. 
 
 The common method of wetting brick by throwing water from 
 buckets or spraying with a hose over a large pile is deceptive, the 
 water reaches a few brick on one or more sides and escapes many. 
 Immersion of the brick for from 3 to 8 minutes, depending upon its 
 quality, is the only sure method to avert the evil consequences of 
 using dry or partially wetted brick. 
 
 Strict attention must be paid to have the starting course level, 
 for the brick being of equal thickness throughout, the slightest 
 irregularity or incorrectness in it will be carried into the superposed 
 courses, and can only be rectified by using a greater or less quantity 
 of mortar in one part or another, a course which is injurious to the 
 work. 
 
MASONRY CONSTRUCTION 
 
 A common but improper method of building thick brick walls 
 is to lay up the outer stretcher courses between the header courses, 
 and then to throw mortar into, the trough thus formed, making it 
 semi-fluid by the addition of a large dose of water, then throwing in 
 the brick (bats, sand, and rubbish are often substituted for bricks), 
 allowing them to find their own bearing; when the trough is filled it 
 is plastered over with stiff mortar and the header course laid and the 
 operation repeated This practice may have some advantage in 
 celerity in executing work, but none in strength or security. 
 
 Amount of Mortar. The thickness of the mortar joints 
 should be about J to f of an inch. Thicker joints are very common, 
 but should be avoided. If the bricks are even fairly good the mortar 
 is the weaker part of the wall; hence the less mortar the better. 
 Besides, a thin layer of mortar is stronger under compression than a 
 thick one. The joints should be as thin as is consistent with their 
 insuring a uniform bearing and allowing rapid work in spreading the 
 mortar. The joints of outside walls should be thin in order to de- 
 crease the disintegration by weathering. The joints of inside walls 
 are usually made from f to J-inch thick. 
 
 The proportion of mortar to brick will vary with the size of the 
 brick and with the thickness of the joint. With the standard brick 
 (8J X 4 X 2J inches), the amount of mortar required will be as 
 follows : 
 
 Thickness of Joints. Mortar required. 
 
 Per Cubic Yard. Per 1,000 Brick. 
 Cubic Yards. Cubic Yards. 
 
 } to J inch 0.30 to 0.40 0.80 to 0.90 
 
 1 " I " 0.20 " 0.30 0.40 " 0.60 
 
 fc " " 0.10 " 0.15 0.15 " 0.20 
 
 Face or Pressed Brick Work. This term is applied to the 
 facing of walls with better bricks and thinner joints than the backing. 
 The bricks are pressed, of various colors, and are laid in colored 
 mortar. The bricks are laid in close joints, usually g-inch thick, and 
 set with an imperceptible batter in themselves, which may not be 
 seen when looking at the work direct, but which makes the joint a 
 prominent feature and gives the work a good appearance. The 
 brick of each course must be gauged with care and exactness, so 
 that the joints may appear all alike. The bond used for the face of 
 
MASONRY CONSTRUCTION 87 
 
 the wall is called the "running bond/' the bricks are clipped on the 
 back, and a binder placed transversely therein to bond the facing 
 to the backing. The joints in the backing being thicker than those 
 of the face work, it is only in every six or seven courses that they come 
 to the same level, so as to permit headers being put in. This class 
 of work requires careful watching to see that the binders or headers 
 are put in ; it frequently happens that the face work is laid up without 
 having any bond with the backing. 
 
 In white-joint work the mortar is composed of white sand and 
 fine lime putty. The mason when using this mortar spreads it care- 
 fully on the bed of the brick which is to be laid in such a way that 
 when the brick is set the mortar will protrude about an inch from the 
 face of the wall. When there are a number laid, and before the 
 mortar becomes too hard, the mortar that protrudes is cut off flush 
 with the wall, the joint struck downwards, and the upper and lower 
 edges cut with a knife guided by a small straight edge. When the 
 front is built, the whole is cleaned down with a solution of muriatic 
 acid and water, not too strong, and sometimes oiled with linseed oil 
 cut with turpentine, and applied with a flat brush. After the front 
 is thoroughly cleaned with the muriatic acid solution, it should be 
 washed with clean water to remove all remains of the acid. 
 
 When colored mortars are required, the lime and sand should 
 be mixed at least 10 days before the colored pigments are added to 
 it, and they should be well soaked in water before being added to 
 the mortar. 
 
 BRICK MASONRY IMPERVIOUS TO WATER. 
 
 It sometimes becomes necessary to prevent the percolation of 
 water through brick walls. A cheap and effective process has not yet 
 been discovered, and many expensive trials have proved failures. 
 Laying the bricks in asphaltic mortar and coating the walls with 
 asphalt or coal tar are successful. " Sylvester's Process for Repelling 
 Moisture from External Walls," has proved entirely successful. The 
 process consists in using two washes for covering the surface of the 
 walls, one composed of Castile soap and water, and one of alum and 
 water. These solutions are applied alternately until the walls are 
 made impervious to water. 
 
88 MASONRY CONSTRUCTION 
 
 EFFLORESCENCE. 
 
 Masonry, particularly in moist climates or damp places, is fre- 
 quently disfigured by the formation of a white efflorescence on the 
 surface. This deposit generally originates with the mortar. The 
 water which is absorbed by the mortar dissolves the salts of soda, 
 potash, magnesia, etc., contained in the lime or cement, and on 
 evaporating deposits these salts as a white efflorescence on the surface. 
 With lime mortar the deposit is frequently very heavy, and, usually, 
 it is heavier with Rosendale than with Portland cement. The efflor- 
 escence sometimes originates in the brick, particularly if the brick 
 was burned with sulphurous coal or was made from clay containing 
 iron pyrites; and when the brick gets wet the water dissolves the 
 sulphates of lime and magnesia, and on evaporating leaves the 
 crystals of these salts on the surface. The crystallization of these 
 salts within the pores of the mortar and of the brick or stone causes 
 disintegration, and acts in many respects like frost. 
 
 The efflorescence may be entirely prevented by applying " Syl- 
 vester's" washes, composed of the same ingredients and applied in 
 the same manner as for rendering masonry impervious to moisture. 
 If can be much diminished by using impervious mortar for the face 
 of the joints. 
 
 REPAIR OF flASONRY. 
 
 In effecting repairs in masonry, when new work is to be con- 
 nected with old, the mortar of the old must be thoroughly cleaned 
 off along the surface where the junction is to be made and the surface 
 thoroughly wet. The bond and other arrangements will depend 
 upon the circumstances of the case. The surfaces connected should 
 be fitted as accurately as practicable, so that by using but little mortar 
 no disunion may take place from settling. 
 
 As a rule, it is better that new work should butt against the old, 
 either with a straight joint visible on the face, or let into a chase, 
 sometimes called a "slip-joint," so that the straight joint may not 
 show; but if it is necessary to bond them together the new work 
 should be built in a quick-setting cement mortar and each part of it 
 allowed to set before being loaded. 
 
 In pointing old masonry all the decayed mortar must be com- 
 pletely raked out with a hooked iron point and the surfaces well 
 wetted before the fresh mortar is applied. 
 
MASONRY CONSTRUCTION 89 
 
 flASONRY STRUCTURES. 
 
 The component parts of masonry structures may be divided 
 into several classes according to the efforts they sustain, their forms 
 and dimensions depending on these efforts. 
 
 1. Those which sustain only their own weight, and are not 
 liable to any cross strain upon the blocks of which they are composed, 
 as the walls of enclosures. 
 
 2. Those which, besides their own weight, sustain a vertical 
 pressure arising from a weight borne by them, as the walls of edifices, 
 columns, the piers of arches, bridges, etc. 
 
 3.. Those which sustain lateral pressures and cross strains, 
 arising from the action of earth, water, frames, arches, etc. 
 
 4. Those which sustain a vertical upward or downward pres- 
 sure, and a cross strain, as lintels, etc. 
 
 5. Those which transfer the pressure they directly receive to 
 lateral points of support, as arches. 
 
 WALLS. 
 
 Walls are constructions of stone, brick, or other materials, and 
 serve to retain earth or water, or in buildings to support the roof and 
 floors and to keep out the weather. The following points should be 
 attended to in the construction of walls: 
 
 The whole of the walling of a building should be carried up 
 simultaneously; no part should be allowed to rise more than about 
 3 feet above the rest; otherwise the portion first built will settle down 
 to its bearings before the other is attached to it, and then the settle- 
 ment which takes place in the newer portion will cause a rupture, 
 and cracks will appear in the structure. If it should be necessary 
 to carry up one part of a wall before the other, the end of that portion 
 first built should be racked back, that is, left in steps, each course pro- 
 jecting farther than the one above it. 
 
 Work should not be hurried along unless done in cement mortar, 
 but given time to settle to its bearings. 
 
 Thickness of Walls. The thickness necessary to be given 
 walls depends upon the height, length, and pressure of the load, 
 wind, etc., and may be determined from that section of applied me- 
 chanics termed ''Stability of Structures." In practice, however, 
 these calculations are rarely made except for the most important 
 
90 MASONRY CONSTRUCTION 
 
 structures, for the reason that if a vertical wall be properly con- 
 structed upon a sufficient foundation, the combined mass will retain 
 its position, and bear pressure acting in the direction of gravity, to 
 any extent that the ground on which it stands and the component 
 materials will sustain. But pressure acting .laterally has a tendency 
 to overturn the wall, and therefore it must be the aim of the con- 
 structor to compel as far as possible, all forces that can act upon an 
 upright wall to act in the direction of gravity. 
 
 In determining thickness of walls the following general prin- 
 ciples must be recognized : 
 
 1. That the center of pressure (a vertical line through the center 
 of gravity of the weight), shall pass through the center of the area of 
 the foundation. If the axis of pressure does not coincide exactly 
 with the axis of the base, the ground will yield most on the side which 
 is pressed most ; and as the ground yields, the base assumes an inclined 
 position, and carries the lower part of the structure with it, producing 
 cracks, if nothing more. 
 
 2. That the length of a wall is a source of weakness and that 
 the thickness should be increased at least 4 inches for every 25 feet 
 over 100 feet in length. 
 
 3. That high stories and clear spans exceeding 25 feet require 
 thick walls. 
 
 4. That walls of warehouses and factories require a greater 
 thickness than those used for dwellings or offices. 
 
 5. That walls containing openings to the extent of 33 per 
 cent of the area should be increased in thickness. 
 
 6. That a wall should never be bonded into another wall 
 either much heavier or lighter than itself. 
 
 In nearly all of the larger cities the minimum thickness of walls 
 is prescribed by ordinance. 
 
 The accompanying table gives the more usual dimensions: 
 
MASOMEY CONSTRUCTION 
 
 91 
 
 > .a ?3 03 3 
 
 o s-i a T ~ | co j-^ 
 
 w g -g >>+* as 
 
 O 3; W f-> o3 . 
 
 S^^la 
 
 |1H*! 
 
 IlIHI 
 
 s 
 
 03 ^ 
 
 02 O >O 'O 'O ^ 
 
 ^ e* co co 
 
 o 10 >o o 
 
 ^j co i> oo o 
 cp 
 
 v^ 4) 03 4) 4) 
 
 ^000 O 
 
 M O O O O 
 
 2 a a a a 
 
 a a a 
 
 03 03 C3 
 
 -III 1 
 8 
 
 O O 10 
 -^ CO t- 
 
 Zg 
 
 B 
 
 ^ 03 
 
 '2 
 
 el 
 ^ g 
 
 4) 03 
 
92 
 
 MASONRY CONSTRUCTION 
 
 RETAINING WALLS. 
 
 A retaining wall is a wall built for the purpose of "retaining" 
 or holding up earth or water. In engineering practice such walls 
 attain frequently large proportions, being used in the construction of 
 railroads, docks, waterworks, etc. 
 
 The form of cross-section varies considerably according to cir- 
 cumstances, and often according to the fancy of the designer. The 
 
 Fig. 23. 
 
 r 
 
 Fig. 24. 
 
 Fig. 25. 
 
 more usual forms are shown in Figs. 22 to 25. The triangular section 
 is the one which is theoretically the most economical, and the nearer 
 that practical consideration will allow of its being conformed to 
 the better. 
 
 All other tilings being equal, the greater the face batter the 
 greater will be the stability of the wall ; but considerations connected 
 with the functions of the wall limit the full application of this con- 
 dition, and walls are usually constructed with only a moderate batter 
 on the face, the <liminution towards the top being obtained by a back 
 
MASONRY CONSTRUCTION 93 
 
 batter worked out in a series of offsets. Walls so designed contain 
 no more material and present greater resistance to overturning than 
 walls with vertical backs. 
 
 Dry stone retaining walls are best suited for roads on account of 
 their self-draining properties and their cheapness. If these dry walls 
 are properly filled in behind with stones and chips, they are, if well 
 constructed, seldom injured or overthrown by pressure from behind. 
 If the stone is stratified with a flat cleavage, the construction of retain- 
 ing and parapet walls is much facilitated. If the stone has no natural 
 cleavage, great care is necessary to obtain a proper bond. If walls 
 built of such stone are of coursed rubble, care is required that the 
 masons do not sacrifice the strength of the walls to the face appearance. 
 The practice of building walls with square or rectangular-faced 
 stones, tailing off behind, laid in rows, one course upon the other, 
 the rear portions of the walls being of chips and rough stones, set 
 anyhow, cannot .be condemned too strongly. Such a construction, 
 which is very common, has little transverse and no longitudinal 
 strength. 
 
 Little 'or no earth should be used for back filling if stone is avail- 
 able. Where earth filling is used, it should only be thrown in and 
 left to settle itself; on no account should it be wetted and rammed. 
 
 Thickness of Walls. Retaining walls require a certain 
 thickness to enable them to resist being overthrown by the thrust of 
 the material which they sustain. The amount of this thrust depends 
 upon the height of the mass to be supported and upon the quality of 
 the material. 
 
 Surcharged Walls, A retaining wall is said to be surcharged 
 when the bank it retains slopes backwards to a higher level than the 
 top of the wall ; the slope of the bank may be either equal to or less, 
 but cannot be greater, than the angle of repose of the earth of the 
 bank. 
 
 Proportions of Retaining Walls. In determining the pro- 
 portions of retaining walls experience, rather than theory, must be 
 our guide. The proportions will depend upon the character of the 
 material to be retained. If the material be stratified rock with inter- 
 posed beds of clay, earth, or sand, and if the strata incline toward 
 the wall, it may require to be of far greater thickness than any ordi- 
 nary retaining wall; because when the thin seams of. earth become 
 
94 MASONRY CONSTRUCTION 
 
 softened by infiltrating rain, they act as lubricants, like soap or tallow, 
 to facilitate the sliding of the rock strata; and thus bring an enormous 
 pressure against the wall. Or the rock may be set in motion by the 
 action of frost on the clay seams. Even if there be no rock, still if 
 *he strata of soil dip toward the wall, there will always be danger 
 of a similar result; and additional precautions must be adopted, 
 especially when the strata reach to a much greater height than 
 the wall. 
 
 The foundation of retaining walls should be particularly secure; 
 the majority of failures which have occurred in such walls have been 
 due to defective foundations. 
 
 Failure of Retaining Walls. Retaining walls generally fail 
 (1) by overturning or by sliding, or (2) by bulging out of the body of 
 the masonry. Sliding may be prevented by inclining the courses 
 inward. An objection to this inclination of the joints in dry walls 
 is that rainwater, falling on the battered face, is thereby carried 
 inwards to the earth backing, which thus becomes soft and settles. 
 This objection may be overcome by using mortar in the face joints 
 to the depth of a foot, or by making the face of the wall nearly 
 vertical. 
 
 Protection of Retaining Walls. The top of the walls 
 should be protected with a coping of large heavy stones laid as headers. 
 
 Where springs occur behind or below the wall, they must be 
 carried away by piping or otherwise got rid of. 
 
 The back of the wall should be left as rough as possible, so as 
 to increase the friction of the earth against it. 
 
 Weep Holes. In masonry walls, weep holes must be left at 
 frequent intervals, in very wet localities as close as 4 feet, so as to 
 permit the free escape of any water which may find its way to the 
 back of the wall. These holes should be about 2 inches wide and 
 should be backed with some permeable material, such as gravel, 
 broken stone, etc. 
 
 Formula for Calculating Thickness of Retaining Walls. 
 E = weight of earthwork per cubic yard. 
 W=weight of wall per cubic yard. 
 H height of wall. 
 T = thickness of wall at top. 
 T = H X tabular number (Table 12). 
 
MASONRY CONSTRUCTION 
 
 95 
 
 TABLE 12. 
 Coefficients for Retaining Walls. 
 
 
 E : W : : 1 : 5 
 
 E : W::l :4 
 
 
 Clay. 
 
 Sand. 
 
 Clay. 
 
 Sand. 
 
 1 in 4 
 
 .083 
 
 .029 
 
 .115 
 
 .054 
 
 1 in 5 
 
 .122 
 
 .065 
 
 .155 
 
 .092 
 
 1 in 6 
 
 .149 
 
 .092 
 
 .183 
 
 .118 
 
 1 in 8 
 
 .184 
 
 ..125 
 
 .218 
 
 .153 
 
 1 in 12 
 
 .221 
 
 .160 
 
 .256 
 
 .189 
 
 Vertical 
 
 .300 
 
 .239 
 
 336 
 
 .267 
 
 Retaining walls of dry stone should not be less than 3 feet thick 
 at top, with a face batter of 1 in 4 and back perpendicular, the courses 
 laid perpendicular to the face batter. Weep holes are unnecessary 
 unless the walls are in very wet situations. 
 
 Retaining walls of masonry should be at least 2 feet thick at top, 
 back perpendicular and face battered at the rate of 1 in 6. 
 
 Surcharged Walls. In calculating the strength of surcharged 
 walls substitute Y for H, Y being the perpendicular at the end of a 
 line, L = H measured along the slope to be retained (Fig. 26).- 
 Y== 1.7IH in slopes of 1 :1; 
 = 1.55H " " "'I-}:!; 
 = 1.35H " " "2:1; 
 ai 1.31H " " "3:1; 
 = 1.24H " " " 4 : 1. 
 
 DESCRIPTION OF ARCHES. 
 
 Basket = Han die Arch : One in which the intrados resembles 
 a semi-ellipse, but is composed of arcs of circles tangent to each other 
 
 Circular Arch : One in which the intrados is a part of a circle. 
 
 Discharging Arch : An arch built above a lintel to take the 
 superincumbent pressure therefrom. 
 
 Elliptical Arch : One in which the intrados is a part of an 
 ellipse. 
 
 Qeostatic Arch: An arch in equilibrium under the vertical 
 pressure of an earth embankment. 
 
 Hydrostatic Arch : An arch in equilibrium under the vertical 
 pressure of water 
 
90 MASONRY CONSTRUCTION 
 
 Inverted Arches are like ordinary arches, but are built with 
 the crown downwards. They are generally semicircular or segmental 
 in section, and are used chiefly in connection with foundations. 
 
 Plain or Rough Arches are those in which none of the bricks 
 are cut to fit the splay. Hence the joints are quite close to each other 
 at the soffit, and wider towards the outer curve of the arch ; they are 
 generally used as relieving <nnl trimrr arches^ for tunnd lining, 
 and all arches where strength is essential and appearance no par- 
 ticular object. In constructing arches of this kind it is usual to form 
 them of two or more four-inch concentric rings until the required 
 thickness is obtained. Each of the successive rings is built inde- 
 pendently, having no connection with the others beyond the adhesion 
 of the mortar in the ring joint. It is necessary that each ring should 
 be finished before the next is commenced; also that each course be 
 bonded throughout the length of the arch, and that the ring joint 
 should be of a regular thickness. For if one ring is built with a thin 
 joint and another with a thick one the one having the most mortar will 
 shrink, causing a fracture and depriving the arch of much of its 
 strength. 
 
 Pointed Arch : One in which the intrados consists of two arcs 
 of equal circles intersecting over the middle of the span. 
 
 Relieving Arch : See Discharging Arch. 
 
 Right Arch : A cylindrical arch either circular or elliptical, 
 terminated by two planes, termed heads of the- arch, at right angles 
 to the axis of the arch. 
 
 Segmental Arch: One whose intrados is less than a semicircle. 
 
 Semicircular Arch: One whose intrados is a semicircle; also 
 called a full-centered arch. 
 
 SKew Arch : One whose heads are oblique to the axis. Skew 
 arches are quite common in Europe, but are rarely employed in the 
 I'nited States; and in the latter when an oblique arch is employed it 
 is usually made, not after the European method with spiral joints, 
 but by building a number of short right arches or ribs in contact with 
 each other, each successive rib being placed a little to one side of its 
 neighbor. 
 
 DEFINITIONS OF PARTS OF ARCHES. 
 
 Abutment : The outer wall that supports the arch, and which 
 connects it to the adjacent banks. 
 
MASONRY CONSTRUCTION 97 
 
 Arch Sheeting : The voussoirs which do not show at the end 
 of the arch. 
 
 Camber is a slight rise of an arch, as J to J inch per foot 
 of span. 
 
 Crown : The highest point of the arch. 
 
 Extrados : The upper and outer surface of the arch. 
 
 Haunches : The sides of the arch from the springing line half 
 way up to the crown. 
 
 Heading Joint : A joint in a plane at right angles to the axis 
 of the arch. It is not continuous. 
 
 Intrados or Soffit : The under or lower surface of the arch. 
 
 Invert : An inverted arch, one with its intrados below the axis 
 or springing line; e.g., the lower half of a circular sewer. 
 
 Keystone : The center voussoir at the crown. 
 
 Length : The distance between face stones of the arch. 
 
 Pier : The intermediate support for two or more arches. 
 
 Ring Course : A course parallel to the face of the arch. 
 
 Ring Stones : The voussoirs or arch stones which show at 
 the ends of the arch. 
 
 Rise : The height from the springing line to under side of the 
 arch at the keystone. 
 
 Skew Back : The upper surface of an abutment or pier from 
 which an arch springs; its face is on a line radiating from the 
 center of the arch. 
 
 Span : The horizontal distance from springing to springing of 
 the arch. 
 
 Spandrel : The space contained between a horizontal line 
 drawn through the crown of the arch and a vertical line drawn through 
 the upper end of the skew back. 
 
 Springing : The point from which the arch begins or springs. 
 
 Springer : The lowest voussoir or arch stone. 
 
 String Course : A course of voussoirs extending from one 
 end of the arch to the other. 
 
 Voussoirs : The blocks forming the arch. 
 
 Arches: The arch is a combination of wedge-shaped blocks, 
 termed arch stones, or voussoirs, truncated towards the angle of the 
 wedges by a curved surface which is usually normal to the surfaces 
 
98 MASONRY CONSTRUCTION 
 
 of the joints between the blocks. This inferior surface of the arch 
 is termed the soffit. The upper or outer surface of the arch is termed 
 the back. 
 
 The extreme blocks of the arch rest against lateral supports, 
 termed abutments, which sustain both the vertical pressure arising 
 from the weight of arch stones, and the weight of whatever lies upon 
 them; also the lateral pressure caused by the action of the arch. 
 
 The forms of an arch may be the semicircle, the segment, or a 
 compound curve formed of a number of circular curves of different 
 radii. Full center arches, or entire semicircles, offer the advantages 
 of simplicity of form, great strength, and small lateral thrust; but if 
 the span is large they require a correspondingly great rise, which is 
 often objectionable. The flat or segmental arch enables us to reduce 
 the rise, but it throws a great lateral strain upon the abutments. The 
 compound curve gives, when properly proportioned, a strong arch 
 with a moderate lateral action, is easily adjustable to different ratios 
 between the span and the rise, and is unsurpassed in its general 
 appearance. In striking the compound curve, the following con- 
 ditions are to be observed: The tangents at the springing must be 
 vertical, the tangent at the crown horizontal, and the number of 
 centers must be uneven, curves of 3 and 5 centers will be found- to 
 fulfil all requirements. 
 
 In designing an arch the first step is to determine the thickness 
 at the crown, i.e., the depth of the keystone. This depth depends 
 upon the form, and rise of the arch, the character of the masonry, 
 and the quality of the stone; and is usually determined by Trautwine's 
 formula, which is as follows for a first-class cut stone arch whether 
 circular or elliptical. 
 
 in which 
 
 D = the depth at the crown in feet. 
 R = the radius of curvature of the intrados in feet. 
 S the span in feet. 
 
 For second-class work, the depth found by this formula may be 
 increased about one-eighth part; and for brickwork or fair rubble, 
 about one-third. 
 
MASONRY CONSTRUCTION 
 
 99 
 
 Table 13 gives the depth of keystone for semicircular arches, 
 the second column being for hammer-dressed beds, the third for beds 
 roughly dressed with the chisel, and the fourth for brick masonry. 
 
 TABLE 13. 
 
 Thickness of Arch in inches. 
 
 Span in feet. 
 
 First-class Masonry. 
 
 Second-class Masonry 
 
 Brick Masonry. 
 
 6 
 
 12 
 
 15 
 
 12 
 
 8 
 
 13 
 
 16 
 
 16 
 
 10 
 
 14 
 
 17 
 
 20 
 
 12 
 
 15 
 
 19 
 
 20 
 
 14 
 
 16 
 
 20 
 
 24 
 
 16 
 
 17 
 
 21 
 
 24 
 
 18 
 
 18 
 
 23 
 
 24 
 
 20 
 
 19 
 
 24 
 
 24 
 
 25 
 
 20 
 
 25 
 
 28 
 
 30 
 
 21 
 
 26 
 
 28 
 
 35 
 
 22 
 
 28 
 
 28 
 
 40 
 
 23 
 
 29 
 
 32 
 
 45 
 
 24 
 
 30 
 
 32 
 
 50 
 
 25 
 
 31 
 
 32 
 
 Thickness of Arch at the Springing. Generally the thick- 
 ness of the arch at the springing is found by an application of 
 theory. 
 
 If the loads are vertical, the horizontal component of the 
 compression on the arch is constant; and hence, to have the 
 mean pressure on the joints uniform, the vertical projection of the 
 joints should be constant. This principle leads to the following 
 formula: 
 
 The length measured radially of each joint between the joint of 
 rupture and the crown should be such that its vertical projection is equal 
 to the depth of the keystone. 
 
 The length of the joint of rupture, i.e., the thickness of the arch 
 at the practical springing line, can be computed by the formula 
 
 z = d sec a 
 
 in which z is the length of the joint, 
 d the depth of the crown, 
 a the angle the joint makes with the vertical. 
 The following are the values for circular and segmental arches: 
 
100 MASONRY CONSTRUCTION 
 
 If - > ~, I = 2.00 d 
 "~ = ~, l=lMd 
 
 
 in which R = the rise, in feet 
 S = the span, in feet. 
 
 Thickness of the Abutments, The thickness of the abut- 
 ment is determined by the following formula: 
 
 t = 0.2 p + 0.1 R + 2.0 
 
 in which t is the thickness of the abutment at the springing, p the 
 radius, and R the rise all in feet. 
 
 The above formula applies equally to the smallest culvert or the 
 largest bridge whether circular or elliptical, and whatever the pro- 
 portions of rise and span and to any height of abutment. 
 
 Table 14 gives the minimum thickness of abutments for arches 
 of 120 degrees where the depth of crown does not exceed 3 feet. 
 
 Calculated from the formula 
 
 T 
 = 
 
 in which D = depth or thickness of crown in feet; 
 
 H = height of abutment to springing in feet; 
 
 R = radius of arch at crown in feet; 
 
 T = thickness of abutment in feet. 
 
 Arches fail by the crown falling inward, and thrusting outward 
 the lower portions, presenting five points of rupture, one at the key- 
 stone, one on each side of it which limit the portions that fall inward, 
 and one on each side near the springing lines which limit the parts 
 thrust outward. In pointed arches, or those in which the rise is 
 greater than half the span, the tending to yielding is, in some cases, 
 different; and thrust upward and outward the parts near the crown. 
 
MASONRY CONSTRUCTION 
 
 101 
 
 TABLE 14. 
 
 Minimum Thickness of Abutments for Arches of 120 Degrees 
 Where the Depth of Crown Does Not Exceed 3 Feet. 
 
 Span of 
 
 Height of Abutment to Springing, in feet. 
 
 Arch. 
 
 5 
 
 7.5 
 
 10 
 
 20 
 
 30 
 
 8 feet 
 
 3.7 
 
 4.2 
 
 4.3 
 
 4.6 
 
 4.7 
 
 9 " 
 
 3.9 
 
 4.4 
 
 4.6 
 
 4.9 
 
 5.0 
 
 10 " 
 
 4.2 
 
 4.6 
 
 4.8 
 
 5.1 
 
 5.2 
 
 12 
 
 4.5 
 
 4.7 
 
 5.2 
 
 5.6 
 
 5.7 
 
 14 
 
 4.7 
 
 5.2 
 
 5.5 
 
 6.0 
 
 6.1 
 
 16 
 
 4.9 
 
 5.5 
 
 5.8 
 
 6.4 
 
 6.5 
 
 18 
 
 5.1 
 
 5.8 
 
 6.1 
 
 6.7 
 
 6.9 
 
 20 
 
 5.3 
 
 6.0 
 
 6.4 
 
 7.1 
 
 7.2 
 
 22 
 
 5.5 
 
 6.2 
 
 6.6 
 
 7.3 
 
 7.6 
 
 24 
 
 5.6 
 
 6.4 
 
 6.9 
 
 7.6 
 
 7.9 
 
 30 
 
 6.0 
 
 7.0 
 
 7.5 
 
 8.4 
 
 8.8 
 
 40 
 
 6.5 
 
 7.7 
 
 8.4 
 
 9.6 
 
 10.0 
 
 50 
 
 6.9 
 
 8.2 
 
 9.1 
 
 10.5 
 
 11.1 
 
 60 
 
 7.2 
 
 8.7 
 
 9.7 
 
 11.4 
 
 1-2.0 
 
 70 
 
 7.4 
 
 9.1 
 
 10.2 
 
 11.8 
 
 12.9 
 
 80 
 
 7.6 
 
 9.4 
 
 10.6 
 
 12.8 
 
 13.6 
 
 90 
 
 7.8 
 
 9.7 
 
 11.0 
 
 13.4 
 
 14.3 
 
 100 
 
 7.9 
 
 10.0 
 
 11.4 
 
 14.0 
 
 15.0 
 
 NOTE. The thickness of abutment for a semicircular arch may be taken from the 
 above table by considering it as approximately equal to that for an arch of 120 degrees 
 having the same radius of curvature; therefore by dividing the span of the semicircular 
 arch by 1.155 it will give the span of the 120-degree arch requiring the same thickness of 
 abutment. 
 
 The angle which a line drawn from the center of the arch to the 
 joint of rupture makes with a vertical line is called the angle of rupture. 
 This term is also used when the arch is stable, or where there is no 
 joint of rupture, in which case it refers to that point about which there 
 is the greatest tendency to rotate. It may also be defined as including 
 that portion of the arch near the crown which will cause the greatest 
 thrust or horizontal pressure at the crown. This thrust tends to 
 crush the voussoirs at the crown, and also to overturn the abutments 
 about some outer joint. In very thick arches rupture may take place 
 from slipping of the joints. 
 
 In order to avoid any tendency of the joints to open, the arch 
 should be so designed that the actual resistance line shall everywhere 
 be within the middle third of the depth of the arch ring. 
 
 In general the design of an arch is reached by a series of approx- 
 imations. Thus, a form of arch and spandrel must be assumed in 
 
102 
 
 MASONRY CONSTRUCTION 
 
 advance in order to find their common center of gravity for the pur- 
 pose of determining the horizontal thrust at the crown, and the 
 reaction at the skewback. 
 
 Backing. The backing is masonry of inferior quality or con- 
 crete, laid outside and above the arch stones proper, to give additional 
 
 Fig. 26. Rowlock Bond. 
 
 Fig. 27. Rowlock with Skewback. 
 
 Fig. 28. Block in Course Bond. 
 
 Fig. 29. Header and Stretcher. 
 
 Fig. 30. Flat Arch. Fig. 31. Relieving Arch. 
 
 security. Ordinarily, the backing has a zero thickness at or near 
 the crown, and gradually increases to the upringing line. 
 
 Spandrel Filling. Since the surface of the roadway must 
 not deviate from a horizontal line, a considerable quantity of material 
 
MASONRY CONSTRUCTION 103 
 
 is required above the backing to bring the roadway level. Ordinarily 
 this space is filled with earth, gravel, broken stone, cinders, etc. 
 Sometimes to save filling small arches are built over the haunches 
 of the main arch. 
 
 Drainage. The drainage of arcn bridges of more than one 
 span is generally effected by giving the top surface of the backing a 
 slight inclination from each side toward the center of the width of the 
 bridge and also from the center toward the end of the span. The 
 water is thus collected over the piers, from whence it is discharged 
 through pipes laid in the masonry. 
 
 To prevent leakage through the backing and through the arch 
 sheeting, the top of the former should be covered with a layer of 
 puddle, or plastered with a coat of cement mortar, or painted with 
 coal tar or asphaltum. 
 
 Brick Arches. The only matter requiring special mention in 
 connection with brick arches is the bond to be employed. When 
 the thickness of the arch exceeds a brick and a half, the bond from 
 the soffit outward is a very important matter. There are three 
 principal methods employed in bonding brick arches: (1) The arch 
 may be built in concentric rings; i.e., all the brick may be laid as 
 stretchers, with only the tenacity of the mortar to unite the several 
 rings. This method is called rowlock bond: (2) Part of the brick 
 may be laid as stretchers and part as headers, by thickening the outer 
 ends of the joints either by using more mortar or by driving in thin 
 pieces of slate, so that there shall b3 the same number of brick in 
 each ring. This form of construction is called header and stretcher 
 bond: (3) Block in course bond is formed by dividing the arch into 
 sections similar in shape to the voussoirs of stone arches, and laying 
 the brick in each section with any desired bond. 
 
 Skewback, In brick arches of large span a stone skewback 
 is used for the arch to spring from. The stone should be cut so as 
 to bond into the abutment, and the springing surface should be cut 
 to a true plane, radiating from the center from which the arch is 
 struck. 
 
 Flat Arches are often built over door or window openings; 
 they are always liable to settle and should be supported by an 
 angle bar, the vertical flange of which may be concealed behind 
 the arch. 
 
104 MASONRY CONSTRUCTION 
 
 Relieving Arches. This term is applied to arches turned 
 over openings in walls to support the wall above; beams called lintels 
 are usually used in connection with this type of arch, the lintel should 
 not have a bearing on the wall of more than 4 inches, and the arch 
 should spring from beyond the ends of the lintel as shown in A, Fig. 31, 
 and not as at B. 
 
 CONSTRUCTION OF ARCHES. 
 
 In constructing ornamental arches of small span the bricks 
 should be cut and rubbed with great care to the proper splay or wedge 
 like form necessary, and according to the gauges or regularly measured 
 dimensions. 
 
 This is not always done, the external course only being rubbed, 
 so that the work may have a pleasing appearance to the eye, while 
 the interior, which is hidden from view, is slurred over, and in order 
 to save time many of the interior bricks are apt to be so cut away as 
 to deprive the arch of its strength. This class of work produces 
 cracks and causes the arch to bulge forward, and may cause one of 
 the bricks of a straight arch to drop down lower than the soffit. 
 
 In setting arches the mason should be sure that the centers are 
 set level and plumb, that the arch brick or stone may rest upon them 
 square. When the brick or stone are properly cut beforehand the 
 courses can be gauged upon the center from the key downwards. 
 The soffit of each course should fit the center perfectly. 
 
 The mortar joints should b? as thin as possible and well flushed up. 
 
 In setting the face stones it is necessary to have a radius line, and 
 draw it up and test the setting of each stone as it is laid. 
 
 The framing, setting up, and striking of the centers are very 
 important parts of the construction of any arch, particularly one 
 of long span. A change in the shape of the center, due to insufficient 
 strength or improper bracing, will be followed by a change in the 
 curve of the intrados, and consequently of the line of resistance, 
 which may endanger the safety of the arch itself. 
 
 CENTERING FOR ARCHES. 
 
 No arch becomes self-supporting until keyed up, that is, until 
 the crown or keystone course is laid. Until that time the arch ring, 
 which should be built up simultaneously from both abutments, has 
 
MASONRY CONSTRUCTION 
 
 105 
 
 to be supported by frames called centers. These consist of a series 
 of ribs placed from 3 to 6 or more feet apart, supported from below. 
 The upper surface of these ribs is cut to the form of the arch, and over 
 these a series of planks called laggings are placed, upon which the 
 arch stones directly rest. The ribs may be of timber or iron. They 
 should be strong and stiff. Any deformation that occurs in the rib 
 will distort the arch, and may even result in its collapse. 
 
 Striking the Center. The ends of the ribs or center frames 
 usually rest upon a timber lying parallel to, and near, the springing 
 line of the arch. This tim- 
 ber is supported by wedges, 
 preferably of hardwood, rest- 
 ing upon a second stick, which 
 is in turn supported by wooden 
 posts, usually one under each 
 end of each rib. The wedges 
 between the two timbers, as 
 above, are used in removing 
 the center after the arch is 
 completed, and are known as 
 striking wedges. They consist 
 of a pair of folding wedges, 1 
 to 2 feet long, 6 inches wide, 
 and having a slope of from 1 
 to 5 to 1 to 10, placed under 
 each end of each rib. It is 
 necessary to remove the cen- 
 ters slowly, particularly for 
 large arches; and hence the 
 striking wedges should have 
 a very slight taper, the larger the span the smaller the taper. 
 
 The center is lowered by driving back the wedges. To lower 
 the center uniformly the wedges must be driven back uniformly. 
 This is most easily accomplished by making a mark on the side of 
 each pair of wedges before commencing to drive, and then moving 
 each the same amount. 
 
 The inclined surfaces of the wedges should be lubricated when 
 the center is set up, so as to facilitate the striking. 
 
 - Weary es w"x/S"x 4- 
 
 Temporary Stone Corbf/ 
 
 Fig. 32. Arch Center. 
 
106 MASONRY CONSTRUCTION 
 
 Screws may be used instead of wedges for lowering centers. 
 
 Sand is also employed for the same purpose. The method fol- 
 lowed is to support the center frames by wooden pistons or plungers 
 resting on sand confined in plate-iron cylinders. Near the bottom 
 of each cylinder there is a plug which can be withdrawn and replaced 
 at pleasure, thus regulating the outflow of the sand and the descent 
 of the center. 
 
 There is great difference of opinion as to the proper time for 
 striking centers. Some hold that the center should be struck as 
 soon as the arch is completed and the spandrel filling is in place; 
 while others contend that the mortar should be given time to harden. 
 It is probably best to slacken the centers as soon as the keystone 
 course is in place, so as to bring all the joints under pressure. The 
 length of time which should elapse before the centers are finally 
 removed should vary with the kind of mortar employed and also 
 with its amount. In brick and rubble arches a large proportion of 
 the arch ring consists of mortar, and if the center is removed too soon 
 the compression of this mortar might cause a serious or even dangerous 
 deformation of the arch. Hence the centers of such arches should 
 remain until the mortar has not only set, but has attained a con- 
 siderable part of its ultimate strength. 
 
 Frequently the centers of bridge arches are not removed for 
 three or four months after the arch is completed, but usually the 
 centers for the arches of tunnels, sewers, and culverts are removed 
 as soon as the arch is turned and, say, half of the spandrel filling 
 is in place. 
 
 BRIDGE ABUTMENTS. 
 
 Form. There are four forms of abutment in use, they are named 
 according to their form as the straight abutment, the wing abutment, 
 the U abutment and the T abutment. 
 
 The form to be adopted for any particular case will depend 
 upon the location whether the banks are low and flat, or steep and 
 rocky, whether the current is swift or slow, and also upon the relative 
 cost of earthwork and masonry. Where a river acts dangerously 
 upon a shore, wing walls will be necessary. These wings may be 
 curved or straight. The slope of the wings may be finished with an 
 inclined coping, or offset at each course. Wing walls subjected to 
 
MASONRY CONSTRUCTION 
 
 107 
 
108 
 
 MASONRY CONSTRUCTION 
 
 FronT. 
 
 PA. M m VA U U j.j 1:1 ti l<\ f:J SI N f) ii 1. 1 M 
 Stringer 1 coping 
 
 Eie vat/on. 
 
 Foundation 
 
 1 
 
 Foundation. 
 
 Plan 
 Fig. 34. Abutment for Railroad Bridge. 
 
MASONRY CONSTRUCTION 109 
 
 special strains, or to particular currents of water require positions 
 and forms accordingly. 
 
 The abutment of a bridge has two offices to perform; (1) to 
 support one end of the bridge, and (2) to keep the earth embankment 
 from sliding into the water. 
 
 The abutment may fail (1) by sliding forward, (2) by bulging, 
 or (3) by crushing. 
 
 The dimensions of abutments will vary with each case, with 
 the form and size of the bridge and with the pressure to be sustained ; 
 the dimensions may be determined by the same formulas as used 
 for retaining walls. 
 
 For railroad bridges the top dimensions are usually 5 feet wide 
 by 20 feet long. The usual batter is 1 in 12, for heights under 20 
 feet the top dimensions and the batter determine the thickness at the 
 bottom. For greater heights, the uniform rule is to make the thick- 
 ness four-tenths the height. 
 
 Bridge abutments are built of first or second-class masonry or 
 of concrete alone or faced with stone masonry, according to the im- 
 portance and location of the structure. 
 
 BRIDGE PIERS. 
 
 The thickness of a pier for simply supporting the weight of the 
 superstructure need be but very little at the top, care being taken to 
 secure a sufficient bearing at the foundation. Piers should be thick 
 enough, however, to resist shocks and lateral strains, not only from 
 a passing load, but from floating ice and ice jams; and in rivers where 
 a sandy bottom is liable to deep scouring, so that the bottom may 
 work out much deeper on one side of a pier than on the other, regard 
 should be paid to the lateral pressure thus thrown on the pier. For 
 mere bearing purposes the following widths are ample for first-class 
 masonry span 50 feet, width 4 feet, span 200 feet, width 7 feet. 
 Theoretically the dimensions at the bottom are determined by the 
 area necessary for stability; but the top dimensions required for the 
 bridge seat, together with the batter, 1 in 12 or 1 in 24, generally 
 make the dimensions of the base sufficient for stability. 
 
 The up-stream end of a pier, and to a considerable extent the 
 down-stream end also, should be rounded or pointed to serve as a 
 cutwater to turn the current aside and to prevent the formation of 
 
110 
 
 MASONRY CONSTRUCTION 
 
 whirls which act upon the bed of the stream around the foundation, 
 and also to form a fender to protect the pier proper from being dam- 
 aged by ice, tugs, boats, etc. This rounding or pointing is designated 
 by the name starling, the best form appears to be a semi-ellipse. 
 The distance to which they should extend from the pier depends 
 upon local circumstances. 
 
 A bridge pier may fail in any one of these ways; (1) by sliding 
 on any section on account of the action of the wind against the ex- 
 
 B 
 
 C 
 
 
 J- -I 
 
 39- * 
 
 1 
 
 i 
 
 --D 
 
 Chcrnnei P/ers 
 
 Fig. 35. Type of Bridge Pier. 
 
 posed part of the pier; (2) by overturning at any section where the 
 moment of the horizontal forces above the section exceeds the moment 
 of the weight of the section ; or (3) by crushing at any section under 
 the combined weight of the pier, the bridge and the load. Bridge 
 piers are usually constructed of quarry-faced ashlar backed with 
 
MASONRY CONSTRUCTION 
 
 111 
 
 rubble or concrete. Occasionally, for economy, piers, particularly 
 pivot-piers, are built hollow sometimes with and sometimes without 
 cross walls. 
 
 CULVERTS. 
 
 Culverts are employed for conveying under a railroad, highway, 
 or canal the small streams crossed. They may be of stone, brick, con- 
 crete, earthenware, or iron pipe or any of these in combination. Two 
 general forms of masonry culverts are in use, the box and the arch. 
 
 Box Culverts. The box consists of vertical side walls of 
 masonry with flagstones on top extending from one wall to another. 
 
 The foundation consists of large stones and the side walls may 
 be laid dry or in mortar. 
 
 1 
 
 
 
 
 \ 
 
 
 
 
 
 
 
 
 I I 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 &'$$& 
 
 '<>W$M>i 
 
 IJU.Ul.Ul. 
 
 $%%$&%/$$ 
 
 ! .-- 
 
 Fig. 36. End Elevation. 
 
 Fig. 37. Section AB. 
 
 1 1.1 
 
 _J 
 
 Fig. 38. Plan. 
 
 Fig. 39. Section CD. 
 T ypcs of Box Culverts. 
 
 The paving should be laid independent of the walls and should 
 be set in cement mortar. The end walls are finished either with a 
 plain wall perpendicular to the axis of the culvert and may be stepped, 
 or provided with wing walls as the circumstances of each case may 
 require. 
 
 The thickness of the cover stone may be determined by con- 
 sidering it as a beam supported at the ends and loaded uniformly. 
 
112 
 
 MASONRY CONSTRUCTION 
 
 Figs. 36 to 39 show the form of this class of culverts and the 
 dimensions given in Table 15 will serve as an approximate guide for 
 general use. 
 
 TABLE 15. 
 Dimensions for Box Culverts. 
 
 Area. 
 
 Opening. 
 
 Side Wall. 
 
 Depth of Cover. 
 
 Length of Cover. 
 
 4 feet 
 
 2' X 2' 
 
 2' X 2' 
 
 12 inches 
 
 5 feet 
 
 9 " 
 
 3X3 
 
 3X2* 
 
 16 " 
 
 6 " 
 
 16 " 
 
 4X4 
 
 4X3 
 
 20 " 
 
 7 " 
 
 25 " 
 
 5X5 
 
 5 X 3. 
 
 22 " 
 
 8 " 
 
 36 " 
 
 6X6 
 
 6X4 
 
 24 " 
 
 9 " 
 
 Arch Culverts. The dimensions of arch culverts are deter- 
 mined in the manner described herein under arches, attention, how- 
 ever, being given to the following points : 
 
 Wing Walls. There are three common ways of arranging the 
 wing walls at the end of arch culverts: (1) The culvert is finished 
 with straight walls at right angles to the axis of the culvert. (2) The 
 wings are placed at an angle of 30 degrees with the axis of the culvert. 
 (3) The wing walls are built parallel to the axis of the culvert, the 
 back of the wing and the abutment being in a straight line and the 
 only splay being derived from thinning the wings at their outer edge. 
 The most economical and better form for hydraulic considerations 
 is the second form. 
 
 Designing Culverts. In the design of culverts care is required 
 to provide an ample way for the water to be passed. If the culvert 
 is too small, it is liable to cause a washout, entailing interruption of 
 traffic and cost of repairs, and possibly may cause accidents that will 
 require the payment of large sums for damages. On the other hand, 
 if the culvert is made unnecessarily large, the cost of construction is 
 needlessly increased. 
 
 The area of waterway required, depends (1) upon the rate of 
 rainfall ; (2) the kind and condition of the soil ; (3) the character and 
 inclination of the surface; (4) the condition and inclination of the bed 
 of the stream; (5) the shape of the area to be drained, and the position 
 of the branches of the stream; (6) the form of the mouth and the 
 inclination of the bed of the culvert; and (7) whether it is permissible 
 
MASONRY CONSTRUCTION 
 
 113 
 
 to back the water up above the culvert, thereby causing it to discharge 
 under a head. 
 
 (1) The maximum rainfall as shown by statistics is about one 
 
 I 
 
 Fig. 40. Sectional Elevation. 
 
 I . I 
 
 I . I 
 
 I . I 
 
 Fig. 41. Plan. 
 
 Fig. 42. Section AB. 
 
 Fig. 43. Section-CD. 
 Type of Arch Culvert. 
 
 inch per hour (except during heavy storms), equal to 3,630 cubic feet 
 per acre. Owing to various causes, not more than 50 to 75 per cent 
 of this amount will reach the culvert within the same hour. 
 
114 MASONRY CONSTRUCTION 
 
 Inches of rainfall X 3,630 = cubic feet per acre. 
 
 Inches of rainfall X 2,323,200 = cubic feet per square mile. 
 
 (2) The amount of water to be drained off will depend upon 
 the permeability of the surface of the ground, which will vary greatly 
 with, the kind of soil, the degree of saturation, the condition of the 
 cultivation, the amount of vegetation, etc. 
 
 (3) The rapidity with which the water will reach the water- 
 course depends upon whether the surface is rough or smooth, steep 
 or flat, barren or covered with vegetation, etc. 
 
 (4) The rapidity with which the water will reach the culvert 
 depends upon whether there is a well-defined and unobstructed chan- 
 nel, or whether the water finds its way in a broad thin sheet. If the 
 watercourse is unobstructed and has a considerable inclination, the 
 water may arrive at the culvert nearly as rapidly as it falls; but if 
 the channel is obstructed, the water may be much longer in passing 
 the culvert than in falling. 
 
 (5) The area of the waterway depends upon the amount of the 
 area to be drained ; but in many cases the shape of this area and the 
 position of the branches of the stream are of more importance than 
 the amount of the territory. For example, if the area is long and 
 narrow, the water from the lower portion may pass through the 
 culvert before that from the upper end arrives; or, on the other hand, 
 if the upper end of the area is steeper than the lower, the water from 
 the former may arrive simultaneously with that from the latter. 
 Again, if the lower part of the area is better supplied with branches 
 than the upper portion^ the water from the former will be carried past 
 the culvert before the arrival of that from the latter; or, on the other 
 hand, if the upper portion is better supplied with branch watercourses 
 than the lower, the water from the whole area may arrive at the culvert 
 at nearly the same time. In large areas the shape of the area and 
 the position of the watercourses are very important considerations. 
 
 (6) The efficiency of a culvert may be materially increased by 
 so arranging the upper end that the water may enter it without being 
 retarded. The discharging capacity of a culvert can also be increased 
 by increasing the inclination of its bed, provided the channel below 
 will allow the water to flow away freely after having passed the culvert. 
 
 (7) The discharging capacity of a culvert can be greatly in- 
 creased by allowing the water to dam up above it. A culvert will 
 
MASONRY CONSTRUCTION 115 
 
 discharge twice as much under a head of four feet as under a head 
 of one foot. This can be done safely only with a well-constructed 
 culvert. 
 
 The determination of the values of the different factors entering 
 into the problem is almost wholly a matter of judgment. An estimate 
 for any one of the above factors is liable to be in error from 100 to 200 
 per cent, or even more, and of course any result deduced from such 
 data must be very uncertain. Fortunately, mathematical exactness 
 is not required by the problem nor warranted by the data. The 
 question is not one of 10 or 20 per cent of increase; for if a 2-foot pipe 
 is insufficient, a 3-foot pipe will probably be the next size, an increase 
 of 225 per cent; and if a 6-foot arch culvert is too small, an 8-foot will 
 be used, an increase of 180 per cent. The real question is whether 
 a 2-foot pipe or an 8-foot arch culvert is needed. 
 
 Calculating Area of Waterway. Numerous empirical for- 
 mulas have been proposed for this and similar problems; but at best 
 they are all only approximate, since no formula can give accurate 
 results with inaccurate data. 
 
 The size of waterway may be determined approximately by 
 the following formula: 
 
 in which 
 
 Q = the number of cubic feet per acre per second reaching the 
 
 mouth of the culvert or drain. 
 C = a coefficient ranging from .31 to .75, depending upon the 
 
 nature of the surface; .62 is recommended for general 
 
 use. 
 r = average intensity of rainfall in cubic feet per acre per 
 
 second. 
 
 S = the general grade of the area per thousand feet. 
 A = the area drained, in acres. 
 
 CONCRETE STEEL MASONRY. 
 
 Concrete in the form of blocks made at a factory, and concrete 
 formed in place and reinforced by steel rods and bars of differing 
 shapes is being substituted in many situations for stone and brick 
 masonry. For the construction of bridges and floors it is extensively 
 
116 
 
 MASONRY CONSTRUCTION 
 
 employed. Several systems are in use, each known by the name of 
 the inventor. Fi^. 44 shows the different types which are more or 
 less popular. 
 
 The Monier type consists of a mesh work of longitudinal and 
 transverse rods of steel, usually placed near the center line of the arch 
 
 Fig. 44. Types of Concrete Steel Arches. 
 
 rib. This type rests on the theory that the steel rods will resist the 
 compressive stresses of the rib, while the concrete acts merely as a 
 stiffener to prevent the steel from buckling, 
 
 The Melan type consists of steel ribs embedded in the concrete 
 and extending from abutment to abutment. The ribs are in the 
 form of steel I-beams curved to follow the center line of the arch rib. 
 The steel is assumed to be sufficient to resist the bending moments 
 of the arch, while the concrete is relied upon to resist the thrust and 
 to act as a preservative coating for the steel. 
 
 The Von Emperger arch is a modification of the Melan arch, 
 the ribs are built up with angles for the flanges and diagonal lacing 
 replaces the web, on the theory that the metal should be concentrated 
 near the extrados of the arch to more effectually resist the w bending 
 moments. 
 
MASONRY CONSTRUCTION 117 
 
 The Thacher type is formed by omitting the web and reinforcing 
 the concrete by steel bars in pairs one above the other, one near the 
 extrados and one near the intrados, the steel being relied upon to 
 resist the bending moments while the concrete is expected to resist 
 the thrust of the arch. 
 
 In the Hyatt arch that portion of the steel bars or rods which in 
 the Thacher arch is subjected to the greatest compression is omitted. 
 
 In the Luter arch the concrete rib is reinforced by tension mem- 
 bers passing from one side of the arch rib to the other. 
 
 In the Hennebique system an arch barrel or drum, four to six 
 inches in diameter, is supported by ribs of concrete below, the concrete 
 of the drum being reinforced with steel rods placed near the extrados, 
 and that of the ribs by steel rods near the intrados. 
 
 Numerous forms of steel shapes are advocated for the reinforce- 
 ment of concrete when employed for arches, retaining walls, etc.; 
 twisted bars, corrugated bars, expanded metal and lock woven steel 
 are some of the names applied to the different shapes. 
 
 The method employed for constructing concrete walls is in brief 
 as follows : A wooden form is erected, consisting of slotted standards 
 made of 6-inch boards nailed together with spacing blocks between 
 them at their ends, f-inch bolts are used to join the standards on 
 opposite sides of the wall. The standards are for the purpose of 
 holding molding boards in position while the coacrete is being de- 
 posited between them. These boards are of dressed pine 1J inches 
 thick. After the lower portions of the concrete has set the boards 
 are removed and used above. Vertical rods of twisted or corrugated 
 steel are built in the wall spaced about 12 inches apart. In some 
 cases level horizontal bars of steel are also embedded in the walls. 
 
INDEX 
 
 Page 
 
 Absorptive power of stones, table 3 
 
 Abutment 96 
 
 definition of 68 
 
 Activity of cement 18 
 
 Adulteration of Portland cement 16 
 
 Age of briquette for testing 23 
 
 Appearance of stone 3 
 
 Arch bricks 8 
 
 Arch culverts 112 
 
 Arch sheeting 97 
 
 Arches 
 
 centering for 104 
 
 construction of 104 
 
 description of 95 
 
 Argillaceous stones 2 
 
 Arris, definition of 63 
 
 Artificial stones 4 
 
 brick 4 
 
 cement 11 
 
 concrete 33 
 
 Ashlar backed with rubble 82 
 
 Ashlar masonry. 79 
 
 Asphaltic concrete 37 
 
 Atmosphere, effect of on stone 4 
 
 Axed V 75 
 
 Backed, definition of 7 63 
 
 Backing 63, 102 
 
 Basket-handle arch 95 
 
 Bats, definition of ". 63 
 
 Batter, definition of 63 
 
 Bearing blocks, definition of 63 
 
 Bearing power of soils 54 
 
 Belt stones, definition of 64 
 
 Blocking course, definition of 64 
 
 Boasted 75 
 
 Bond, definition of 64 
 
 Bond of ashlar masonry 80 
 
 Box culverts HI 
 
 Breast wall, definition of 65 
 
 Brick 4 
 
 color of Q 
 
120 INDEX 
 
 Page 
 Brick 
 
 manufacture of 6 
 
 rank of 8 
 
 size and weight of 9 
 
 Brick arches 103 
 
 Brick ashlar, definition of 65 
 
 Brick masonry 
 
 impervious to water 87 
 
 rules for building 84 
 
 Bridge abutments 106 
 
 Bridge piers 109 
 
 Briquettes, testing 24 
 
 Broached 75 
 
 Broken ashlar 81 
 
 Build, definition of 65 
 
 Building stone, requisites for 2 
 
 appearance 3 
 
 cheapness 3 
 
 durability 2 
 
 strength. 3 
 
 Bush hammer 73 
 
 Bush hammered. 75, 78 
 
 Buttress, definition of 65 
 
 Caissons 51 
 
 Calcareous stones 2 
 
 Camber ..* 97 
 
 Cavil .... 73 
 
 Cement 
 
 activity of 18 
 
 color of - 17 
 
 fineness of x 18 
 
 preservation of 26 
 
 quick and slow setting .... 19 
 
 soundness of 20 
 
 testing of 16 
 
 weight of 17 
 
 Cement mortar 29 
 
 Cementing materials 11 
 
 classification 11 
 
 composition 11 
 
 use , 13 
 
 Centering for arches 104 
 
 Cheapness of stone 3 
 
 Chemical classification of rocks 2 
 
 argillaceous 2 
 
 calcareous 2 
 
 silicious 2 
 
 Cherry bricks 8 
 
INDEX 121 
 
 Page 
 
 Chisel 74 
 
 Chiselled 75 
 
 Circular arch 95 
 
 Clay puddle 38 
 
 Cleaning down, definition of 65 
 
 Clinker bricks 8 
 
 Closers, definition of 65 
 
 Coefficients for retaining walls, table 95 
 
 Cofferdams 49 
 
 Color of bricks 6 
 
 Color of cement 17 
 
 Compass brick. . . . , 8 
 
 Concrete 33 
 
 asphaltic 37 
 
 depositing under water 36 
 
 laying 35 
 
 mixing 34 
 
 proportions of materials for 33 
 
 strength of 33 
 
 weight of 33 
 
 Concrete piles , 43 
 
 Concrete with steel beams 48 
 
 Concrete steel masonry. 115 
 
 Coping, definition of 65 
 
 Corbell, definition of 66 
 
 Cornice, definition of 66 
 
 Counterfort, definition of 66 
 
 Course, definition of 66 
 
 Cramps, definition of. _ 66 
 
 Crandall 73 
 
 Crandalled 75^ 76 
 
 Cribs 50 
 
 Crown of arch . 97 
 
 Culverts - HI 
 
 designing of 112 
 
 Cut stones ,. . . 79 
 
 Cutwater, definition of 4 . . . , 67 
 
 Deadening 75 
 
 Depositing concrete under water 36 
 
 Designing culverts 112 
 
 Designing the footing 56 
 
 Designing the foundation 52 
 
 area required 54 
 
 bearing power of soils 54 
 
 load to be supported 52 
 
 Discharging arch 95 
 
 Double-face hammer 73 
 
 Dowels, definition of . . 67 
 
122 INDEX 
 
 Page 
 
 Drafted 75 
 
 Drainage 103 
 
 Dressed work 75 
 
 Dressing the stones 72 
 
 Droved 75 
 
 Dry stone walls 67 
 
 Durability of stone 2 
 
 .Efflorescence 88 
 
 Elliptical arch 95 
 
 Extrados 97 
 
 Face, definition of 67 
 
 Face brick 8 
 
 Face hammer 73 
 
 Faces of cut stone, methods of finishing 76 
 
 Facing, definition of 67 
 
 Feather-edge brick 8 
 
 Fine pointed 76 
 
 Fineness of cement 18 
 
 Fire-brick 10 
 
 Flat arches 103 
 
 Footing, definition of 67 
 
 Footings 
 
 offsets of 56 
 
 steel I-beam 58 
 
 stone 56 
 
 timber ."...' 57 
 
 Formula for calculating thickness of retaining walls 94 
 
 Foundation, designing 52 
 
 Foundations 39 
 
 artificial 40 
 
 on clay 40 
 
 on gravel 39 
 
 on mud 41 
 
 natural 39 
 
 pile ...., 41 
 
 on rock 39 
 
 on sand 40 
 
 in water 41 
 
 Freezing of mortar 31 
 
 Freezing process 52 
 
 Frost, effect of on stone 4 
 
 Gauged work, definition of '. '. 67 
 
 Geological classification of rocks 1 
 
 igneous 1 
 
 metamorphic .' 1 
 
 sedimentary 1 
 
 Geostatic arch 95 
 
 Grout definition of ;..... 67 
 
INDEX 123 
 
 Page 
 
 Hammer dressed 75 
 
 Hand hammer -74 
 
 Hard bricks 8 
 
 Hard kiln-run brick : . . . 8 
 
 Haunches 97 
 
 Header, definition of 68 
 
 Heading joint 97 
 
 Herring bone 75 
 
 Hollow cylinders 49 
 
 Hydraulic limes 14 
 
 Hydrostatic arch 95 
 
 Igneous rocks 1 
 
 Intrados . 97 
 
 Inverted arches 96 
 
 Iron piles 42 
 
 Jamb, definition of 69 
 
 Joggle, definition of 69 
 
 Joints, definition of 68 
 
 Keystone 97 
 
 Kiln-run brick 8 
 
 Laying concrete 35 
 
 Limes 13 
 
 hydraulic 14 
 
 poor 14 
 
 rich 13 
 
 Lintel, definition of 69 
 
 Load to be supported 52 
 
 Machine-made brick 7 
 
 Machine tools 75 
 
 Mallet , 74 
 
 Manufacture of brick... 6 
 
 Masonry 
 
 classification of ' 63 
 
 ashlar 79 
 
 broken ashlar 81 
 
 rubble \ 81 
 
 squared-stone 80 
 
 repair of 88 
 
 safe working loads for 59 
 
 Masonry structures 89 
 
 Memoranda of cements 25 
 
 Metamorphic rocks ." 1 
 
 Mixing concrete 34 
 
 Mortar 27 
 
 freezing of 31 
 
 proportions 28 
 
 sand for 28 
 
 uses of 27 
 
124 INDEX 
 
 Page 
 Mortar 
 
 water for 29 
 
 Moulded concrete piles 43 
 
 Natural cement 14 
 
 Natural stones, classification of 1 
 
 Nigged 75 
 
 Offsets of footings 56 
 
 One-man stone, definition of 69 
 
 Pallets, definition of 70 
 
 Parapet wall, definition of 69 
 
 Patent hammer 74 
 
 Pean hammer 73 
 
 Pean hammered 77 
 
 Physical classification of rocks 1 
 
 stratified 1 
 
 unstratified 1 
 
 Pick ! 73 
 
 Picked 75 
 
 Pier. 97 
 
 Pile driving 44 
 
 Pile foundations 41 
 
 example of 55 
 
 Piles 
 
 concrete 43 
 
 iron 42 
 
 moulded concrete 43 
 
 screw 43 
 
 splicing of 47 
 
 steel 42 
 
 timber 41 
 
 Pitched , 75 
 
 Pitched-face masonry, definition of 70 
 
 Pitching chisel 74 
 
 Plain 75 
 
 Plain arches 96 
 
 Plinth, definition of 70 
 
 Plug 74 
 
 Point 74 
 
 Pointed 75 
 
 Pointed arch. . 96 
 
 Pointing, definition of 69 
 
 Polished 75 
 
 Poor limes 14 
 
 Portland cement 15 
 
 adulteration 16 
 
 blowing 16 
 
 expansion and contraction 16 
 
INDEX 125 
 
 Page 
 Portland cement 
 
 fineness 15 
 
 overlimed 16 
 
 setting 16 
 
 specific gravity 15 
 
 tensile strength 15 
 
 Pozzuolanas 27 
 
 Preservation of cements 26 
 
 Preservation of stone 4 
 
 Pressed brick 7 
 
 Pressed brick work 86 
 
 Prison 76 
 
 Puddling 38 
 
 Quarry-faced masonry, definition of 70 
 
 Quick and slow setting cement . .' 19 
 
 Quoin, definition of 70 
 
 Random tooled 76 
 
 Relieving arch 96, 104 
 
 Re-pressed brick 7 
 
 Retaining walls 92 
 
 coefficients for 95 
 
 definition of 71 
 
 failure of 94 
 
 formula for calculating 94 
 
 proportions of 93 
 
 protection of 94 
 
 Retempering mortar 31 
 
 Reveal, definition of 71 
 
 Rich limes 13 
 
 Right arch , 96 
 
 Rip-rap, definition of 71 
 
 Ring course 97 
 
 Ring stones 97 
 
 Rise, definition of 65, 71 
 
 Rise of arch 97 
 
 Rock faced 76 
 
 Rocks 1 
 
 chemical classification 2 
 
 geological classification , . 1 
 
 physical classification 1 
 
 Roman cement 27 
 
 Rosendale cements 14 
 
 Rough pointed , . 76 
 
 Rubble masonry 81 
 
 Rustic 76 
 
 Safe working loads for masonry 59 
 
 Salmon bricks 8 
 
 Sampling cement . 12 
 
126 INDEX 
 
 Page 
 
 Sand for mortar 28 
 
 screening 29 
 
 washing 29 
 
 Sanded brick 7 
 
 Scabble 76 
 
 Screw piles 43 
 
 Sedimentary rocks 1 
 
 Segmental arch 9G 
 
 Semicircular arch 96 
 
 Sewer brick 8 
 
 Sheet piles 49 
 
 Silicious stones 2 
 
 Sill, definition of 71 
 
 Skew arch 96 
 
 Skewback 97, 103 
 
 Slag cements. 26 
 
 Slope-wall masonry, definition of 71 
 
 Soffit 97 
 
 Soft bricks 8 
 
 Soft-mud brick 7 
 
 Soundness of cement 20 
 
 Spall, definition of 71 
 
 Span of arch 97 
 
 Spandrel 97 
 
 Spandrel filling 102 
 
 Specific gravity of Portland cement. 15 
 
 Splicing piles 47 
 
 Splitting chisel 74 
 
 Springer 97 
 
 Springing of arch 97 
 
 Square droved 76 
 
 Squared-stone 78 
 
 Squared-stone masonry. 80 
 
 Starling, definition of 67 
 
 Steel I-beam footings : 58 
 
 Steel piles ? 42 
 
 Stiff-mud brick ' 7 
 
 Stone cutting 72 
 
 definitions of terms used in 75 
 
 tools used in 73 
 
 Stone footings 56 
 
 Stone masonry, rules for laying all classes of 82 
 
 Stone paving 71 
 
 Stones 
 
 absorptive power of 3 
 
 artificial 4 
 
 brick 4 
 
 cement 11 
 
INDEX 127 
 
 Page 
 Stones 
 
 concrete 33 
 
 preservation of . , 4 
 
 tests for 3 
 
 absorptive power 3 
 
 effect of atmosphere. . - % 4 
 
 effect of frost 4 
 
 Stratified rocks 1 
 
 Strength of stone under compression 3 
 
 Stretcher, definition of 71 
 
 String course 97 
 
 definition of ,. 71 
 
 Striped. 76 
 
 Stroked 75 
 
 Structural materials 1 
 
 Surcharged walls 93 
 
 Tables 
 
 box culverts, dimensions for 112 
 
 bricks, size and weight of 9 
 
 cement and sand, amount required for 1 cu. yd. of mortar 32 
 
 coefficients for retaining walls 95 
 
 depth of keystone for semicircular arches 99 
 
 I-beam footings, safe projection of 59 
 
 masonry footing courses, safe offset for 57 
 
 minimum thickness of abutments for arches of 120 101 
 
 pile-diving dimensions 47 
 
 specific gravity, weight, and resistance to crushing of brick 10 
 
 specific gravity, weight, and resistance to crushing of stones 5 
 
 stones, absorptive power of 3 
 
 tensile strength of cement mortar 25 
 
 weight of masonry ". 53 
 
 Templets, definition of 63 
 
 Tensile strength of Portland cement. 15 
 
 Testing briquettes 24 
 
 Testing cements ; 16 
 
 Tests of activity 18 
 
 Tests of soundness of cement 20 
 
 Tests for stone 3 
 
 absorptive power 3 
 
 effect of atmosphere 4 
 
 effect of frost 4 
 
 Thickness of abutments 100 
 
 Thickness of arch at springing 99 
 
 Timber footing 57 
 
 Timber piles 41 
 
 Tooled 76 
 
 Tooth axe 73, 77 
 
 Tooth chisel... 74 
 
128 INDEX 
 
 Page 
 
 Toothed 7(i 
 
 Toothing, definition of 71 
 
 Two-men stone, definition of 71 
 
 Unsquared stones 78 
 
 Unstratified rocks 1 
 
 Vermiculated worm work 76 
 
 Voussoirs 97 
 
 Walls 89 
 
 Water for mortar 29 
 
 Waterway, calculating area of . . 115 
 
 Weep holes 94 
 
 Weight of cement 17 
 
 Wing walls 112 
 
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