Concrete Pavements, Sidewalks, Curb and Gutter PREPARED BY THE INFORMATION BUREAU UNIVERSAL PORTLAND CEMENT CO. PUBLISHED BY THE Universal Portland Cement Co, CHICAGO PITTSBURGH MINNEAPOLIS FIRST EDITION. 1913 INTRODUCTORY PROBABLY no divisions of concrete construction are more closely allied than Pavements, Sidewalks, Curb and Gutter. In addition to the fact that all are often laid in close proximity, there is a decided similarity in ma- terials and methods of construction. Much repetition can be saved by combining the points common to all, as has been done in the first part of this booklet, deal- ing later more specifically with each type. It is ob- vious, then, that the first section should be studied, no matter which of the three constructions the reader is particularly interested in. Illustrations are often of more educational value than volumes of text, and failures are frequently more beneficial when studied than examples of perfect work, consequently not only successes but typical failures, will be discussed with the hope that defective work may eventually disappear. Copyright 1913 UNIVERSAL PORTLAND CEMENT CO. Chicago Pitttburfh Minneapolis Table of Contents Page Concrete Pavements, Sidewalks, Curb and Gutter (General Discussion) Qualifications for Good Paving Material ....... 7 Materials for Making Concrete,,. ........ 8 General Construction Details ......... 20 Concrete Pavement Construction: Concrete the Most Economical Permanent Pavement Material and Qualifications Equipment . Types of pavement Preparation of Foundation Crown .... Placing Concrete and Reinforcing Table of Concrete Pavements placed in 1911 Pavement calculations and examples Concrete Sidewalk Construction: Advantages of One-Course Walk Preparation of Foundation and sub-grade Forms Recommended Proportions Placing Cost Sidewalk Calculations . Curb and Gutter Construction: Various Types .... Forms, Materials, Foundations, etc Construction of Curb Construction of Curb and Gutter One-Course Work Cost Commercial Forms: Various Types .... Tampers, long handled tools, etc. Specifications : Pavement . Sidewalks . Curb and Curb and Gutter 26 2O66O1O LJ H u EC U z o U U i Concrete Pavements, Sidewalks, Curb and Gutter The appreciation and need for highway improvement are becoming keener each year. An increasing and progressive population demands the most advanced and best adapted construction for every meef e *W purpose. Pedestrian and all other kinds of traffic require a requirements comparatively smooth and even surface, which concrete, in- telligently handled, will give. For minimum traction resist- ance, a pavement must be hard and rigid enough to support without change of form, whatever may come upon it; this requirement concrete also fulfills. An ideal pavement, whether for foot or other traffic, is one which will remain the same under all climatic and weather conditions, is non- absorbent, dustless, easily cleaned, and low in first cost and mainte- nance. Concrete measures up well to all these requirements, and ap- proaches closely the ideal pavement. Nevertheless, the success of concrete in the pavement depends not only upon knowledge of methods, care and skill in manipulation, but like any other construction, upon the selection of proper and durable materials. Figure 2 Concrete pavement in Kansas City. Missouri -7- Concrete Pavements, Sidewalks, Curb and Gutter Materials The sand and gravel found in different sections of the country comes from various banks, each having its own peculiar grading and charac- teristics. The crushed stone may vary in hardness, in gradation, or may be coated with dust in such a manner as to make it unfit for use without treatment; consequently the aggregates should receive careful thought and scrutiny before a definite selection is made. On the other hand, when the Portland cement comes from a reputable manufacturer, careful inspection is not advisable unless the quantity of work will justify the expense. In such a case, confidence should only be placed in laboratories with complete and standard equipment. The methods for testing, adopted by the American Society of Civil Engineers, January 20, 1904, with subsequent amendments, should be used and the cement should comply with the Standard Specifications for Portland Cement of the American Society for Testing Materials, adopted June, 1904, together with subsequent changes and amendments, or the Specifications and Methods adopted by the U. S. Government (Bureau of Standards, Circular No. 33). A sack of cement has a net weight of 94 pounds, and can be considered in volume as equal to one cubic foot, which greatly simplifies propor- tioning. Different brands of cement give slightly different shades of color in the concrete, therefore where uniformity of color is desired, one brand of cement should be used throughout the work. Aggregate Concrete is no stronger than its aggregate. It makes no igure 3 Clean materials only, are suitable for concrete construction. Where clean aggregates are not obtainable, some means must be provided for washing. The above illustration shows one method used for separating sand and gravel, washing the materials at the same time. The bank gravel shown in the left background is shovelled upon the slanting screen which is kept flooded by a stream of water drawn by a centrifugal pump from the nearby river. In the foreground is shown the gravel pile, and at the right the sand pile. Universal Portland Cement Co. difference how well the cement may test, if the gravel, sand or stone does not possess the necessary requisites, the job will be a failure. Good appearing sand or gravel will sometimes develop charac- *sel*ction ^eristics which may disfigure and even destroy the work into necessary which it enters. Quite often, shaly pebbles which are not noticeable except under careful scrutiny will, when used in the concrete, disintegrate, and in so doing expand, breaking out large pieces of top mortar. When such particles occur in the sand, the disin- tegration gives the whole surface a pitted appearance, disfiguring the work. Clay is also detrimental when occurring as a coating on the par- ticles, and in many places it is absolutely necessary to provide a washing apparatus, which will remove it. Many installations of com- mercial types of washers are in satisfactory use. However, by spreading the material out on a loose board platform, in small quantities and turning on a stream from a %-inch garden hose, very satisfactory results have been obtained. When the job is not too large, this same process can be applied to the washing of sand. The apparatus illustrated in Figure 3 is combined so as to wash and screen in the same operation . The size and gradation of the different particles as well as the clean- liness of the surfaces, will materially affect the strength of the concrete. The size of the sand grains has a decided influence upon the strength and is clearly illustrated by the following diagram, in which size of sand * ne so ^^ columns represent the relative areas for the same grains volume of spheres of different sizes (which may be consider- ed as sand grains) and the open columns represent the effect of size of sand grains on the strength of cement-sand mortar. As the making of a first-class concrete necessitates the perfect covering of every particle of sand with cement, and every particle of the coarser Relative areas for the -same volume of spheres of differenf sices , and the effect of size of sand grams on . the sfpengfh of morfor SOUD DIAGBAMS RfPRESE NT AREAS OPEN DIAGRAMS REPRESENT -STRENGTH Figure Concrete Pavements, Sidewalks, Curb and Gutter aggregate with the cement-sand mortar, it is apparent that materials with an excess of fine particles should be avoided. The same line of reasoning is applicable to the combined aggregate in the concrete. It does not necessarily follow, though, that because coarse particles have the smallest area per unit of volume that the aggregate should all be large, since particles of the same size have a large amount of open Voids s P ace between and consequently require a maximum of cement to fill it up. The open spaces between the particles of aggregate are technically called "voids" and naturally have an influence upon the amount of cement required. The voids in sand will average around 33 per cent, while in stone or gravel, the open space averages in the neigh- borhood of 45 per cent. In proportioning concrete for maximum strength and density, it is necessary to use more cement than that actually required to fill the voids in the sand and more mortar than necessary to fill the stone voids exactly. In the specifications and recommendations which are made later for mixtures, an average con- dition for the country has been assumed and the proportions specified according to the best practice for the type of construction used. For minimum voids and the best concrete, the size of the fine aggre- gate should grade from % inch in the largest dimensions, down to the finest, with the coarser particles predominating, and in no case should fine aggregate be used, of which more than four per cent passes through a sieve having 100 meshes per linear inch. The United States Geological Survey, Bulletin No. 331, Series R, Structural Materials 3, has furnished some very valuable data on the value of sands and limestone screenings found throughout the United States, which should be studied by all who are interested in this im- portant subject. The results show, distinctly, the comparative value of sand and limestone screenings, which vary in the relative proportions of the different sized grains, as well as the quality of the material. Comparative Value of Sands Sam- Source Per Per * % Retained on Sieve No. Compressive Str. at 1 Yr. A. her of Supply Location cent of Voids of Silt 1:3 mortar in Ibs. per sq. inch. 10 20 30 40 50 Thru 50 I Bank Sand Attica, Ind 34.0 3.9 4.1 10.3 10.0 19.0 13.8 30.0 4475 1 Bank Sand Attica, Ind 26.9 0.7 27.1 20.9 10.4 14.3 7.2 7.3 7750 3 River Sand St. Clair River. 40.5 2.0 1.0 1.8 2.0 8.5 25.3 00. 2729 4 River Sand St. Clair River. 29.7 0.2 39.5 27. 5 11.0 9.4 0.8 4.7 0742 6 Limestone St. Louis, Mo . 42.1 10.1 9.9 40.3 13.7 7.9 7.2 31 . 4908 o Limestone Greenfield, Ohio 37.. 5 1.1 44.4 21.4 8.5 4.9 3.4 17.4 8400 The sieve number refers to number of meshes per linear inch. Comparing Samples 1 and 2, taken from the same bank near Attica, Indiana, and differing only in size of grains, it will be noticed that when made up into a 1 :3 mortar, the compressive strength of sample 2 is Universal Portland C ' e m ent Co. Sample No. 3 Figure 5 Showing sands of tars made from them. 2729 Ibs. per sq. in. with strengths of mcr- (The sands repre- sented by Samples 1 and 2 were screened from a gravel of glacial origin at Attica, Indiana. This ma- terial is excavated by steam shovel, screened into sev- eral sizes and washed. Samples 1 and 2 illustrate very clearly the possible variation in sands taken from the same de- posit, and also in a general way give a fairly correct idea of the appearance of a well graded sand. From the table opposite can be obtained the granulometric an- alysis, together with the relative strength under compression when mixed in a 1 : 3 mortar. The sands repre- sented by Samples 3 and 4 were taken from the St. Clair River by a centri- fugal pump. Since taken from the same stream, their composition and general char- acter, excepting size of particles, must naturally be quite identical. By reference to the table, as well as the illustrations, it will be seen that Concrete P are merits , Sidewalks, Curb and Gutter the two sands are very different in granule metric composition; also that the compres- sive strength of the two sands when made up into a 1 :3 mortar, is very much in favor of the coarser sand. The limestone screenings repre- sented by Sample 5 were taken from a crushing plant near St. Louis. Of the crusher run ma- terial 50 per cent, passed through 34-inch screen. The grad- ing of the screen- ings is not at all uniform, as shown by the granulo- metric analysis. Sample 6 was taken from a crush- ing plant at Green- field, Ohio, and represents the screenings separat- ed from the crusher run material by %- inch screen. With the exception of the largeamountoffine material the screen- ings are very well graded, and the strength devel- oped when mixed in the proportion of 1:3 is very much superior to that developed by Sam- ple 5, when mixed in the same pro- portion.) ple N 8400 Ibs. per sq. in. Figure 6 Showing sand and screenings of varying coarseness with strength of mortars made from them. 12 Universal Portland Cement Co. more than 70 per cent greater than the compressive strength of Sample 1. As other conditions are the same, it is reasonable to conclude that the low strength shown by Sample 1 is due entirely to poor gradation and excess of fine particles. Like conditions prevail with Samples 3 and 4 taken from the St. Clair river, near Detroit, Michigan. Sample 3 is a very fine sand, 60 per cent passing the 50 mesh sieve, and the effect of such fine material is readily discernible in the compressive strength. Sample 4, which represents a well graded sand from the same stream, gives a compressive strength nearly 150 per cent greater than Sample 3. That a large proportion of fine particles in limestone screenings is detrimental, is shown by the tests on Samples 5 and 6. Here also, the compressive strength is in favor of the coarser material, Sample 6 being more than 70 per cent stronger than Sample 5. Especial care should be exercised in the selection of limestone screen- ings and laboratory results should not always be taken as indicative of the same action in the field. It is possible through careful kneading and mixing in the laboratory to obtain excellent test strengths Limestone on li mes t O ne screenings containing an excessive amount of ungs just. However, when this same material is placed in the mixer on the work, it has a tendency to ball up and often produces a very chalky and unsatisfactory concrete. Some advance the theory, in explaining the frequent occurrence of poor concrete resulting from the use of limestone screenings, that the water is absorbed from the concrete by the limestone particles subsequent to mixing, causing a poor surface bond. On account of the nature of the material, granite rock has not as much tendency to dust, under crushing, as limestone, and so in general, presents a better surface for the cement. An additional advan- Gramte i & g e [ s the high resistance to abrasion which is especially essen- nngs j.- a j j or ^ e wearm g surface, and any material used in a surface having heavy wear, should be hard enough to scratch glass. The usual commercial granite screenings are graded in size from 24-inch down to the finest and should of course be free from an excessive amount of dust. Sometimes, screenings can only be obtained in w r hich the particles run up to }/-inch in largest dimensions, in which case screening over %-mch screen and remixing in the specified proportions are recommended. Coarse Aggregate. The finer aggregates have previously played the most important part in providing suitable and durable wearing surfaces, and until lately the coarse aggregates were used only in the base of the pavement, and were never exposed to the wear direct. How- ever, with the introduction and general adoption of single-course work, the importance of careful selection of such materials is further increased. Good gravel can be obtained in almost any locality and its existence often determines whether the one or two-course pavement is specified Gravel ^ or roa dways. Where the materials must be shipped in for the wearing surface, the two-course road using granite screenings in the top mortar is probably the most economical. The gravel should always be clean; when not so, washing is recommended. The largest dimension will be determined by the type of work into which it enters. (' DH c ret e P a r e in e n t ,v , Sidewalks, 'Curb and Gutter The smallest size should be not less than J^-inch; in other words the sand should be separated out before proportioning. Limestone also makes a satisfactory coarse aggregate for use when it does not take the wear direct as in a sidewalk or pavement, and mestone ^ s ^ ree ^ rom dust. If covered with dust, the adhesion between the limestone and the cement mortar is interfered with. Most limestone if free from dust, will show a distinct sparkle when the surface is ex- amined in the sun. A chalky surface should be sufficient cause for rejection, since it provides nothing to which the cement may bond, and a poor con- crete almost always will result from the use of materials so coated. In size, the limestone should vary from^-inch up to \]/% inches in dimensions, but such can rarely be obtained since it is the practice for most quarries to furnish materials, all the pieces of which are approximately the same size, due to the different sized screens through which they have passed. In such a case the use of the 1 ]/2-inch stone is gen- erally recommended. Crushed granite usually is available in the same sizes as the crushed limestone, and should preferably be graded from \}/% inches down to % inch in dimension. It is preferred to the limestone because of its hardness, but is not C ranite K (>ncr ally used for the one-course pavement because of the diffi- culty in spreading, the angular pieces seeming to catch under the strike board and pull out of the concrete rather than work in like the rounded pieces of gravel. When used in the wearing surface the possibilities Universal Portland Cement Co. granite is specified in two sizes, the one from ^ mcn down and the other from ^ inch to J/2 mcn m dimension. The second grade helps to form a durable surface, which is, of course, the object in any paving material. The service which a concrete pavement gives, depends not only upon the quality of the materials but upon the proper relation between the amounts of different sizes. Many fail to appreciate this point and consequently build pavements using the bank run of gravel Bank without any 'dea of the gradation and distribution of the sizes of various particles. From analyses of a number of samples from different pits, the proportion of fine to coarse material has been found to vary greatly, in the majority of instances there being an excess of sand. When an analysis of the bank run shows this condition, it is often possible by screening and remixing in the proper proportions to add more coarse material, thereby cheapening the construction cost without loss in strength. Thus, in a number of cases, the contractor will be repaid for the extra labor required for screening bank gravel both in cement saved as well as in the satisfaction that his work has been constructed uniformly a requirement especially necessary in road improvement. The illustration, Figure 8, shows plainly the different strata in a gravel pit. It is clear that such a pit will give gravel of varying qual- Figure 8 Showing the various strata and variation in che averag? sand bank. In order to pro- vide against loam in aggregate coming from such a bank, thorough washing or else stripping to the base of the dark streaks is necessary. Concrete Pavements, Sidewalks, Curb and Gutter ities, depending upon what proportion of the different layers is included, as well as what section of the bank the material is taken from. By screening, a practically uniform sand and gravel are assured. The darker streak, which can be seen along the upper edge of the bank, and extending down through the strata, shows black loam, which is often the cause of trouble in concrete construction. In the majority of instances, the loam occurs only on the surface above the gravel, and can be removed by stripping. In this case, even though the top layer were removed, trouble would still be experienced from the leads which are carried down and through the bank, emphasizing the need for a thorough investigation of the materials to be used in concrete. Water. Oftentimes it is necessary to look further than the gravel bank to locate the cause of poor work, and many times the quality of water used in the mixing contributes toward unsatisfactory concrete. The tendency to use water from pools or stagnant ponds, because of a slight saving in labor and equipment, should be discouraged and only clean water of a quality fit for drinking purposes should be used. Sub-Base Materials. Although water is a necessary material in mixing concrete, its presence under the finished pavement is liable to cause trouble unless some means is provided for caring for it. If the soil has naturally good drainage, no further provision is necessary; if not, a sub-base is essential and should be composed of a material which will remain porous indefinitely. For this purpose steam cinders, gravel, crushed stone, slag or other durable materials are recommended. Broken brick have been suggested, but should not be used unless hard burned, because of their tendency to disintegrate from frost action. accd on grades as high as 18%. Universal Portland Cement Co. Colorings. The use of coloring matter in roadways, sidewalks, curb and gutter, is becoming more general every year, because of the realization that the reflected glare from a white or nearly white surface is annoying and the feeling that it is injurious to the eyes is growing. Some sidewalk specifications provide for the coloring of all sidewalk surfaces. The coloring matter commonly used is lampblack or iron oxide. Any mineral coloring may be used if the quantity required to give the desired shade does not exceed ten per cent of the weight of the cement. Lampblack is permanent while some of the other colors have at times given trouble from fading after being placed in the work. The following paragraph and table are taken from "Cements and Concrete" by *Louis C. Sabin, and contain suggestions which will be of value where coloring w T ork is contemplated: "The dry mineral colors mixed in proportions of 2 to 10% of the cement gives shades approaching the color used. Bright colors are difficult to obtain and would not be in keeping with a masonry structure except in architecture. When mixed with an American Portland cement mortar containing one part cement to two parts by weight of a yellow river sand, the particles of which are largely quartz, the colors indicated in the following table were obtained:" "With no coloring matter added, the mortar was a light greenish slate when dry. Ultramarine green, in amounts up to 8 per cent of the cement, had no apparent effect on the color of this mortar. Variations in character of cement and sand will affect the result obtained in using coloring matter. The colors indicated below *Gen. Supt., St. Mary's Falls Canal, Sault Ste. Marie, Michigan, Member Amer. Soc. of C. E. Figure 10 Placing concrete pavement at Mason City, Iowa. 17 Concrete Pavements, Sidewalks, Curb and Gutter are for dry mortar. When the mortar is wet, the shades are usually darker. None of the materials mentioned in the tables seems to affect the early hardening of the mortar, though very much larger proportions might prove injurious." Colored Mortars Colors Given to Portland Cement Mortars Containing Two Parts River Sand to One Cement Dry Material Used Weight of Dry Coloring matter to 100 Lbs. Cement. Cost of Col- oring mat- ter per Ib. (cents). H Pound 1 Pound 2 Pounds 4 Pounds Lamp Black . . Light Slate. . . . Light Gray Blue Gray Dark Blue Slate 15 Prussian Blue. Ultramarine Blue Yellow Ochre. Burnt Umber Light Green Slate Light Green. . . Light Pinkish Slate Light Blue Slate Light Blue Slate Pinkish Slate.. Blue Slate .... Blue Slate Bright Blue Slate. 50 20 3 10 Bright Blue Slate Light Buff Chocolate Dull Lavender Pink Venetian Red. Slate, Pink Tinge Bright Pinkish Slate Light Dull Pink Dull Pink VA Chattanooga Iron Ore.. . . Light Pinkish Slate Dull Pink Light Terra Cotta Light Brick Red 2 Red Iron Ore Pinkish Slate . . Dull Pink Terra Cotta... Light Brick Red VA A very slight difference in the amount of coloring used, will cause variations in the shade of the finished work; consequently, all materials must be measured accurately. Some writers suggest Accurate measur- that enougn top be mixed for the entire job, so as to ing of color mate- . .,. , -i i i rials necessary insure uniformity but this is not always possible where the work is of large size. If the coloring matter, cement and sand are very carefully weighed out or measured for each batch, and the coloring mixed with the cement before the sand is added; then the coloring, cement and sand uniformly mixed dry before adding the water, the result should always be uniform and satisfactory. Collecting Sacks. While the careful collecting and care of cloth cement sacks has nothing to do with the quality of concrete construc- tion, they are details which should be looked to with care by the con- tractor who wishes to keep costs at the minimum. With cement at $1.50 per barrel, the value of a cloth sack is over 25% of the value of the cement contained in it, and yet through carelessness in handling, many are hopelessly torn, thereby losing cement, as well as the sack. Care should be exercised also in preventing the sacks from becoming wet since the cement hardening in the cloth fibre makes the sacks worth- less for refilling. After emptying, the sacks should be spread in piles U niversal Portland Cement Co. along the work, collected, counted and bundled every day. Such a system will materially cut down costs, not only in labor but by keeping the sacks in better condition. Expansion Joint Filler. For filling expansion and contraction joints, asphalt, paving pitch, or tar is recommended which will compress before allowing the pavement to heave. The poured fillers must have two essential characteristics. To be satisfactory, they must remain ductile under the range of temperature to which subjected, and under no conditions become sticky. Felt is also used satisfactorily for this purpose. Care should be exercised to see that the material for the expansion joints is so placed that it will prevent any foreign matter from lodging in the joint after being in place and thus destroy its value. Expansion Joint Protection. In sidewalks and curb and gutter construction, the ordinary half-inch rounded corner is sufficient protec- tion. In roadways, the wear and impact are much greater, making some other treatment desirable. A 2 inch x 2 inch angle properly anch ored makes a very satisfactory protection for the concrete but the anchors must be firmly attached, so as to prevent any motion of the angle after being placed. Special shapes, consisting of a plate curved to fit the street crown with portions punched out for the anchor, are manufactured by the R. D. Baker Company, Detroit, Michigan. Pain re U Placing a two-course driveway with metal forms. 19- Concrete Pavements, Sidewalks, Curb and Gutter Construction Preparation of Sub-Grade. Conditions throughout the country are so variable that it is manifestly impossible to lay down any set of rules which will be applicable in every section. Where the soil is sandy, no sub-base is necessary, while in other soils, the neglect of a proper sub-base might result disastrously. The necessity of the sub-base must, therefore, be left to the discretion of the builder or the successful practice in the cunimunity. If the soil at the excavated grade is firm and solid, there is no necessity for further preparation, but if any soft or spongy places are disclosed, they should be removed and the holes filled with firm material packed solidly. When the sub-grade occurs on fills, its preparation requires extra care, since many failures can be traced to this cause. The different parts should be tamped in layers not to exceed 6 inches in thickness. Wherever available, the intelligent use of water will assist materially in compacting the fill. Drains. If water accumulates in the sub-grade there is danger of upheaval from frost. In soil where the sub-base and natural drainage cannot take care of the water, some other means must be provided. The best method of supplying additional drainage depends upon the available outlets, etc. In some places a broken stone trench suffices, while in other localities a tile drain is necessary. Well made tile are recommended for this purpose; for sidewalks, the 4- inch size is gener- ally adequate, but smaller sizes should not be used, as they fill up with mud and clog the drain. Figure 12 By means of a boom and bottom dump bucket, a large area can be covered without shifting the position of the engine and mixing machine. Universal Portland Cement Co. Measuring of Materials. Upon uniformity of measurements depends the success of concrete construction. Even though the speci- fied proportions are correct, if variation in the relative amounts of materials takes place the pavement will have merit only in proportion to the quality of the poorest sections. Consequently, it is necessary that after the proportions are fixed, means be provided for insuring Figure 13 Four-foot measuring box. Every 3 inches in height represents a volume of one cubic foot. unvaried adherence throughout the work. Particular attention should be directed toward insuring uniform loading of wheelbarrows. The exact proportions can generally be attained by striking off the material with a straight edge or template. If the barrows cannot be struck off to the even proportion, the use of a bottomless measuring box of known volume is recommended to obtain the exact quantities required. A sack of cement weighing 94 pounds net should be considered as one cubic foot, and all batches should be mixed in multiples of an entire sack. Mixing. The amount of material which should be mixed at one time depends upon the facilities for placing the concrete when mixed. Not more than thirty minutes should be allowed to elapse between the time of mixing and the time of placing. The thoroughness of mixing should never vary, however, no difference what the size of the gang or the type of mixer. For hand mixing of concrete, a watertight platform is recommended, on which is first spread the sand, and then the required amount of cement. Two laborers, one on each side, should systematically turn the cement . . into the sand, with a slight "flip" on leaving the shovel, " ng being sure to cut to the bottom of the pile at each stroke. This operation will have moved the location of the pile about two feet. Reversing the direction of the operation brings the pile to its original position, but in a mixed condition. If of uniform color, the required amount of gravel or stone may be distributed over the pile.* Two more turnings should thoroughly mix in the coarse material *By cutting into the pile with a shovel, an idea of the uniformity of mixing can easily be obtained. The appearance of streaks indicates the need for another turning. Concrete Pavements, Sidewalks, Curb and Gutter Figure 14 Horse dra from the mixer. dump-cart for distributing concrete and should make the mixture ready for the water, which should be added in the form of a spray, while the laborers are turning over the pile, as described for mixing the sand and cement. The water should never be added faster than it can be taken up by the materials. As the mixing progresses, it will be noted that the mass becomes more plastic and appears wetter. Water should not be substituted for thorough mixing. It is customary to mix mortar by hand in the usual mortar- Mixing b X ' n * portant that the con- ~***^ crete be kept well sprinkled and not per- mitted to dry out. In hot weather, the pave- ment should not be thrown open to traffic until at least ten days old, and in cool weath- er traffic should be kent nff even Inno-^r Figure 33 Baker plates, used for protecting expansion j Kept OJ even Ollgei. being prepared for use. Expansion Joints. That expansion and contraction of con- crete pavements must be provided for is admitted by all, but how best to do this, where and how far apart and how wide to make the joints are probably the most discussed questions in connection with this class of construction. That joints of any character running parallel with the axis of the street should not be used has been clearly demonstrated in 39 Two thicknesses of tar paper of a width equal to the thickness of the pavement provide the separation. The plates have the same crown as the roadway and are shipped flat, the prongs being bent out with a short length of pipe just before placing. Concrete V a r c m ent s , iS idewal k v , C urb and Gutter practically every case where such joints have been made, but room for expansion must always be left between the edges of the pavement and the curb; one-half inch joint being ample for the widest pavements. Transverse joints should be placed across the street perpendicular to the axis of the pavement, not over thirty feet apart, and all expansion joints should extend through the entire thickness of the pavement. Open transverse joints should be as near one-quarter of an inch in width as it is practicable to make them, but not over one-half inch. They should be filled with suitable bitumen which will not become soft and run out in hot weather, nor hard and brittle and chip out in cold weather; and the edges of the concrete at the joints should be protected with suitable metal protecting plates. A satisfactory transverse joint, illustrated in Figure 33 may be formed by clamping the metal protecting plates to 34 inch metal division plates or to two thicknesses of */g inch tar paper or felt cut to conform to the cross section of the pavement. The assembled joint is staked into position on the sub-grade and concreted in place. Where tar paper or felt is used, this is left in place, but wliere metal division plates are used they should be withdrawn after the concrete has hardened suffi- ciently to hold the protecting plates. The space is later filled with suitable filler. Gravel Shoulders. On lightly travelled highways, the traffic can generally be handled over a width of concrete much narro\ver than is necessary for the trunk roads. In order to provide for passing vehicles, the width can be increased by adding shoulders of gravel containing clay as a binder. Since such shoulders are only used for the purpose of turning out, the wear is not excessive. Figure 1 illustrates the section recommended for the shoulders. Fijure 34 Filling the expansion joint. Universal Portland Cement Co. The following table from "Engineering and Contracting" for April 3, 1912, gives an idea of the cost of concrete pavements constructed during 1911, in a number of cities. Table Showing Amount, Average Price and Some Details of Concrete Pavements in 1911, in a Number of Cities CITIES Sq. Yds. Av. price per sq. yd. includ ing grading. Guar- antee Years Total thick- ness of pave- ment, inches Pro- por- tions. Portland, Me ll,2S8x $1.29 6 1:2^:5 Lynn, Mass 21,402 .70 5 G 1:2 :4 Trenton, N. J 2,826 .44 1 6 1:2 1/2" :5 Seymour, Ind 1,250 .90 3 7 I* 1 Edwardsville, 111 8,950 .40 y.. 7 2 1:3 :5 Alpena, Mich 13,000 .30 8 1:6 Kscanaba, Mich 12,000 .87 6/4 Fond du Lac, Wis ll,043x .25 5 Q]/2 1:2^:5 Sheboygan, Wis 19,860x .28 &A 5 Bemidji, Minn 19,826 .90* 2 5 1:3^9 Burlington, Iowa 4,489 .34 5 6% 1:2 ":5 Cedar Rapids, Iowa 2,178 . 16* 7 6 1 :3 :5 Davenport, Iowa 13,208 .23* 2 7 6 1:3 :5 Fort Dodge, Iowa 7,900 .60 5 7 7 1:3 :5 Marshalltown, Iowa 14,000 .18 7 1:3 :5 Mason City, Iowa 42,000 .30 5 7 s 1 :2 :5 Sioux City, Iowa 100,000 .20 5 1-3 :4^ Kansas City, Mo 81,000 .05 5 6 Grand Island, Neb 3,754 .30 Omaha, Neb 4,485 South Omaha, Neb 13,200 .30 5 6 io 1:2^:5 Kansas City, Kas .09 5 6 Ottawa, Kans 996 .03* 2 6 i:2 :3 Wichita, Kans 2,137 .00* 2 6 1:2 :4 Billings, Mont 2,000 2.25 g 7}-'2 11 1:6 Boise, Idaho 23,166 1. 12* 6 1:3 :5 12 Grand Junction, Colo 18,000 2.20 7 1 :! 1:3 :6 Vancouver, Wash 15,220 1.15 5 Portland, Ore 31,417 Salem, Ore 85,266 1.30* 6 1:2' :4 *Does not include grading. xlleinforced. J l-6 mix; 1-2 surface. 2 5-inch base, 1-3-5 mix; 2 inch top of 1 cement, 1 small gravel, 1 sand. 3 4 inch base, 2 inch wearing surface. 4 5 inch base, 1-23^-5; 1^ inch top, 1 cement, 1 sand, 1 gravel. 5 6>2 inch at gutter, 8 l / 2 inch at center. 5 inch 1-3-5 mix; 2 inch top 1-2. 7 5 inch base, 1-3-5; 2 inch top 1-1-1. 8 5 inch base 1-2-5; 2 inch top 1-2. !% inch 2-3 grout: 5]^ inch 1-7 mix. 10 6 inch and 8 inch. lx Laid in 6 inch gravel base; pavement; 6 inch 1-6 gravel base and 1}-^ inch 1-2 mortar top. 12 Also 1-3-7. 13 5 inch base, 2 inch top. 14 5inch of 1-3-5 and 1% inch of 1-2. Concrete Pavements, Sidewalks, Curb and Gutter Pavement Calculations Width of Concrete Sq. Yards per 100 ft. 9 feet... ...100 12 feet 133| 14 feet 155 5/9 16 feet 177 7/9 18 feet 200 20 feet 222 2/9 To obtain cubic yards of concrete required for pavement 4 inch thick multiply area in square yards by 4/36, or 0. Ill 11 5 inch thick multiply area in square yards by 5/36, or 0. 13889 6 inch thick multiply area in square yards by 6/36, or 0. 16667 7 inch thick multiply area in square yards by 7/36, or 0. 19444 8 inch thick multiply area in square yards by 8/36, or 0. 22222 1 1 /2 inch thick multiply area in square yards by 1/24, or 0. 04167 2 inch thick multiply area in square yards by 1/18, or 0. 05556 Assuming 1 sack cement = 1 cu. ft., 1 cu. yd. of concrete requires: Mixture Bbls. Cement Cu. Yds. Sand Cu. Yds. Gravel 1:1^:3 1.91 0.42 0.85 1:2 :3 1.74 0.52 0.77 1:2 :4 1.51 0.45 0.89 1:2^:5 1.24 0.46 092 1:3 :5 1.16 0.52 0.86 \-.\Yz 3.87 0.86 1:2 3.21 0.95 Examples Example No. 1 : Road or pavement 1500 feet long, 18 feet wide, one-course, 7 inches thick, mixture 15 (length in hundred feet) 200 (number of square yards per 100 feet length) 0.19444 (number of cubic yards per square yard area) = 583.32 cubic yards of concrete. f 1.91 =1111 barrels cement 5S3.-32 \ 0. 42 = 245 cubic yards sand ( 0. 85 = 496 cubic yards gravel Example No. 2: Road or pavement 1500 feet long, 18 feet wide; two-course; base 6 inches thick, mixture 1:3:5, top 1M inches thick, mixture 1:1^>. I (1.16 = ] 0. 52 = [ 0. 86 = Base 15 x 200 x 0. 16667 = 500. 01 cubic yards =580 barrels cement 500. 01 \ 0. 52 = 260 cubic yards sand 430 cubic yards gravel Top 15 x 200 x 0. 04167 = 12.5. 01 cubic yards i AI / s - 87 = 484 barrels cement L*5. ui ^ Q 86 = log cubic yardg ^j Total 580 + 484 = 1064 barrels cement 260 + 108 = 368 cubic yards sand 430 + = 430 cubic yards gravel U niv er sal Portland C ement Co. Concrete Sidewalk Construction Concrete is now accepted as the ideal material for sidewalk con- struction. The great latitude or methods of operation make many different types of construction possible, and it is with regret that the prevalence of the steel trowel finished surface is acknowledged. A glassy finfeh is far from ideal both as to beauty and safety of pedestrians. All modern architects feature the ideal surface obtained by bush hammering or rough casting our concrete surfaces because of the pleasing effect obtained. Yet many persist in demanding a '"shine" upon the sidewalks. Another custom now quite general is the specification of two -course Advantages s i dewa lk or one- . rr , 1 . coarse work work - . This condition will not remain, how- ever, since more and more of our cities are beginning to appreci- ate the advantages of the monolithic one-course slab. With this treatment, it is possible for the work 55 Breaking up alk construction. .estone flags making way for to he its own inspector because of the impos- sibility cf finishing the concrete, if enough cement has not been used in the mix. Another advantage in the one-course sidewalk is uniform character; the entire mass is wearing surface. One layer naturally can be placed more cheaply thrfn two, and the additional strength is such that the equivalent of a five-inch two-course walk can probably be obtained by four and one-half inches of the richer mix, placed in one operation. The'n, too, the actual amount of materials are nearly identical for each type. Below is shown the comparison of the two constructions based on 100 square feet of surface: TYPE Mixture Bbls. Cement Cu. Yds. Sand Cu. Yds. Gravel Total Cost Materials 5-inch Two-Course .... 1:2^:5 base 1:1 J-3 top 2.52 .'80 1.21 $6.79 4^-inch One-Course. . . 1:2 :3 2.42 .73 1.08 $6.16 Concrete Pare tu e n t .v , Sidewalks, Curb and Gutter The foregoing calculations were made on the same basis for both the 5-inch and the 4 i 2-inch walk; viz. Portland cement at $1.50 net, sand at $1/25 per en. yd. and gravel at $1.50 per cu. yd. It is plain, then, that the saving is not alone in labor, but in cost of materials. Foundation. In the construction of a walk, it is necessary that the foundation be built so that neither time nor the elements can change its ability to support the walk. Improperly constructed fills and poor sub-bases result in a great many defective walks. Typical examples of such defects are shown in Figures 36 and 38. It is true that a crack through the center of a walk may not nec- essitate its rebuild- ing, but when it is understood that a perfect walk can be obtained with so little additional effort, such failures are inexcus- able. If the founda- tion settles to any great extent, the walk will practically be de- stroyed unless it is built strong enough to resist breaking, and tilt instead. Sub-Grade. As walks seldom rest upon the top of the ground it is usually necessary to prepare the sub-grade upon which the sub-base or foundation is laid. This is done by either of the two methods shown in Figure 37. If the soil at the excavated grade is firm and solid, there is Figure 36 Crack through center of a 6 foot walk resulting from poor foundation. /* /oio m grot/net. Ftfure 37 Detail of sidewalk. Universal Portland Cement Co. no necessity for further preparation, but if it contains any soft or spongy places, these should be removed and the holes filled with firm material packed solidly. When the sub-grade occurs on fills, its preparation requires more care, and it is not strange that many failures can be traced to improperly made fills. The material should be placed and tamped in layers not to exceed 6 inches in thickness. When the material and conditions will permit, the intelligent use of water will assist greatly in compacting a fill. The reason for extending the fill and sub-base beyond the walk at the line of the sub-grade, shown in Figure 37, is made evident by Figure 38. Here the breaking off of the edge of the walk was due to the fact that the fill was made too narrow, and then left unprotected. The sides of the fill and sub-base should be given a slope of about 1:1/^, so that it will not slip away, and w T hen granular materials are used, the slope should be banked with sod or clay. The sub-base should be flooded and tamped on the sub-grade to the proper level, giving a pitch toward the gutter of %" to the foot. This should be done on approximately the lines shown in Figure 37, though the sub-grade may be an imaginary line as is the case when fills are made of the same material as used in the sub-base. Forms. Two-inch lumber is in general use for sidewalk forms, although several types of metal forms possess particular merit, and are described later under "Commercial Forms." Curv ^ or f rmm g curves, a strip of metal or thin wood can be used, being careful to drive enough stakes to hold in position against tamping of the concrete. Figure 38 -The illustration shows plainly the necessity of providing a proper fill and then preserving it. In this case the fill was of sand and scarcely wider chan the walk. Not being properly protected it was rapidly destroyed and at this point the walk was undermined nearly y$ of its width. Concrete Pavements, Sidewalks, Curb and Gutter I 1 1 1 s ' S I ( luV 1 ^-D- IT ITU 1 ( 1 DETAILS Figure 39 Forms for sidewalk construction. To insure a perfect joint between adjoining slabs a metal cross form may be. used made up of %' metal with stiffeners along the top edge. c f A very satisfactory joint can be obtained, however, by tamping the concrete against a wooden cross form prior to its removal for filling in the slab adjacent. This construction is shown very plainly in Figure 39. As soon as the side forms are placed and securely staked to the Figure 40 The importance of exercising care in placing a joint or surface marking in a walk imme- diately over the joint in the base is shown above. In this case the surface marking was a little to one side of the joint in the base and parallel with it. A slight motion in the foundation caused a crack to occur immediately over the joint in the base, but it would have followed the surface marking if this had been properly placed. Universal Portland Cement Co. finished grade, the division lines should be marked plainly upon each side of the work with wax crayon. This locates the position of the cross form as well as the dividing line which should cut through by the groover exactly at these points after the top is placed. Figure 40, shows an example where the divisions in the top and base were not coincident. The question of width of sidewalks is a very important one. The tendency has been to make the sidewalks too narrow and the street pave- ments too wide in both business and residence streets. The pavement should be narrow on a residence street, for economy, width not being necessary for the traffic, and cost, comfort and beauty being favor- ably affected by reducing the width of the pavement and throwing the space thus saved into a lawn, preferably between the curb and the paved strip of sidewalk. If a street railway should later occupy the street, or business traffic should crowd it, the curbs can be set back, and the street pavement widened at the first necessity of repaving. This has been done in Indianapolis, where the ratio of paved street surface on residence streets without street car tracks is 50% of the total street width in narrow streets, and even less in streets of over 60 feet between prop erty lines. Experience clearly shows that since pedestrians must needs travel in both directions on business streets, the sidewalks should be as w ^ e as P ss ible, even at the expense of comfort in the street. Many more people are delayed and inconvenienced by narrow sidewalks than by narrow streets, if the street traffic is properly regulated and required to keep always to the right side of the street. There must be a difference between wholesale and retail streets, and there should be a regulation of the use of sidewalks as well as of streets. Figure 41 The necessity for providing perfect joints is distinctly shown above where the joints of the old work were continued through the new, due to imperfect joints It is evident thac had the joint in the center of the walk opened, the cracks would not have occurred: also that the cracks discontinued at points where real ioints were provided Concrete Pare m c n t s , Side ic a I k s , Curb and Gutter On a retail business street, the first and most important consideration is the pedestrian traffic. Second is the regularly moving traffic, including the momentary stoppage of vehicles to let off passengers, and third is the standing of vehicles along the curb while the occupants are attending to business in shops, stores and offices. Fifteen feet is a narrow sidewalk for a busy retail street, and should be the minimum limit if it is in any way possible to take care of the street traffic on the remainder of the street width. On wholesale streets, street pavement width is somewhat more important if wagons must back up to the curb for loading and unloading; and foot traffic is much less. But there should be strict regula- tion of the use of the side- walks in handling goods, otherwise the passageway for pedestrians will be reduced enough to cause inconven- ience and delay. Regardless of the width Figure 42 Showing the operation of cutting through the top surface in two-course work with a pointing trowel before using the grooving tool. slab should contain more than 36 square feet an the length ,.. f , , should not exceed Size of slabs , i. one and one-halt times the width. This regu- lation, of course, applies only to walks resting directly upon the ground. In the business districts, vaults under the sidewalks are desirable and are generally obtained with concrete arches supported upon steel I-beams or by rein- forcing the concrete. Where reinforcing is used, the size of the slab is immaterial. of the sidewalk, no individual Figure 43 After cutting trowel the joint is finished wi through the top with the th a groover. In the business section, the thickness will generally exceed C inches while in the residence district, five inches is sufficient for the ordinary _, . street sidewalk, and four and one-half inches in one-course work. The thickness of the wearing course for two-course sidewalk is influenced by the wear to be received. In general the top of a five-inch walk should be three-quarters of an inch thick, which should be increased for the walks of greater thickness or carrying more traffic. Surface Drainage. Since the slabs are constructed of uniform thickness, drainage must be obtained by tilting the walk slightly. For Universal Portland Cement Co. Figure 44 Template for sidewalk construction. Figure 45 Strike Board used for gauging base and striking top. Water this purpose the form nearest the street should be placed slightly below the inside form, the accepted pitch being one-quarter of an inch to the foot. Where walks are placed through yards, parks or private grounds, a very satis- factory method of obtaining drainage is to give the top a slight crown, and accomplished with a curved template, as shown in Figure 44. The amount of pitch should be about equal to one-quarter of an inch to the foot from the center to the edges ; thus a four-foot walk would have a one-half inch crown. Proportions. Although there may be a great deal of allowable variation in proportions for concrete sidewalks, it is safe to say that for all purposes the best results can be obtained with the use of a mixture of one (1) part Portland cement, to two and one-half (2^) parts of fine aggregate, to five (5) parts of coarse aggregate for the concrete. For the mortar top the mixture should not be leaner than one (1) part Portland cement to .'-c^np^f^-^^, two (-2) parts of fine aggre- gate. The same precautions jLJBP** are necessary in maintaining the proportions as outlined -. . " heretofore. The consistency of the base concrete should be such that moisture just ap- pears on the surface after thorough tamping. For the top mixture enough water should be used so that the mortar will not show a grain, ^51 but spread easily under the Figure 46 Showing the edger in operation Straight edge Or template; it Concrete Pavements, Side walks, Curb and Gutter should not be made thin enough to flow, sincn mortar of this kind is of inferior quality. Placing. When the sub-grade and sub-base have been properly prepared and the cross-forms placed, the concrete can be deposited, starting at one end of the work and filling and striking off with a straight edge up to the first cross form. The excess material can be scraped over into the next form. The concrete is tamped down, which will probably provide the required top thickness. This can be gauged by using a strike similar to that shown in Figure 45, in which the ends are notched out to the proper thickness. One side may be used for a gauge, and the other side for leveling the concrete. With the tamping in the first slab complete, the cross form may be removed and the next slab filled and tamped in the same manner, being careful not to break down the perpendicular division joint. The kJ ec t f this extreme care in providing joints is to insure against the appearance of cracks, due to slight, uneven settlement in the foundation. As soon as possible after the base is tamped, the top mortar should be applied and spread evenly over the surface, using the side forms as guides. When sufficiently hardened, the top should be floated with a wooden float. The divisions should be cut through with a pointing trowel, exactly above the divisions in the base, and which were previously located by marking the side forms with wax crayon. Moving the straight edge to the left a distance equal to half the width of the groover, allows the joint to be molded into shape. The edges fi . , should now be finished by running the edger along the forms. The wooden board has probably left a few indentations in the walk, which should be floated out. Without using a straight edge, the groover should now be run over the divisions and the edger along the side forms to leave the work with an unmarred surface. In a number of cities, the steel trowel finish is still common practice. The operations are identical with those described for the wooden float, Trowel finish w ^h ^ ie exception that the first finishing employs both the wooden and steel trowel, but as it is not necessary to finish the joints twice, the labor is about the same. For constructing a one-course sidewalk, the operations of form setting and mixing are identical with the two-course work, except that the forms need not be as wide and the mixing of the top mortar is One-course dispensed with. In filling the forms it is necessary to heap up sidewalk the concrete slightly so that tamping will just bring to grade. A wetter mixture is recommended than for the two-course work so that an easy working mortar is provided. The use of the special tamper shown in figure 16 will be of assistance in forcing the coarser aggregate away from the surface and in flushing the mortar to the top. Carelessness of one kind encourages another and when walks are being laid where it is possible to run in long stretches, one frequently sees Fractional a fractional part of a slab left over at quitting time, and when slabs work is resumed, new concrete is placed against the portion which Universal Portland Cement Co. was previously laid and a top spread over the whole. As the bond between the two concrete bodies is weak at best, a crack will invariably occur at the juncture. A fractional part of a slab should never be left over upon suspending work even for the noon hour. The concrete should be packed against the cross forms so that when placing of concrete is resumed, it will start from a vertical joint between abutting slabs. Any concrete left over at the time work is suspended should be discarded if the work is stopped long enough to permit of any hardening or perceptible drying out of the mass. Wherever a walk is crossed by a drive- > the f thickness of the base should be in- creased at least two inches and the top should have a mini- mum thickness of one and one-quarter inches. Walks are some- times laid with too Driveway ased by hardened concrete work allowed to remain in Grades Figure 47 Fractional slab a over from the previous day's form. steep a pitch for safety, and although there may be little objection to them in fair weather, such walks become impassable when iced over dur- ing the winter season. Wooden walks are sometimes laid over the cement to provide a surer foothold, but this expedient would be unnecessary if steps were built where the grade exceeds twenty per cent. Lesser grades are improved by laying the run with sufficient slope to afford drainage and putting in risers at suitable intervals. A further improvement is to give a roughened finish to the run by means of a wooden trowel or grooving tool, or by imbedding safety tread strips as shown in Figure 48. The comfort of pedestrians demands that the grade in a walk shall not change suddenly, excepting where steps are advisable. It is not 51 Figure 48 A novel way of providing for the comfort of pedes- trians on steep grades by inserting safety tread strips in the walk when laid. Concrete Pavements, Sidewalks, Curb and Gutter unusual to find a break in continuity of the grade, such as is illustrated in Figure 50. Here, the higher walk was built last and is connected de* f ^ *^ e lower by a sharp bevel. The passerby, unprepared for this interruption, is sure to receive a shock. If this walk had been built right, the change in grade would have been extended over the length of an entire slab. There was yet another abrupt change of grade between the point where the picture was taken and the last crossing, although the street was level throughout this distance. It would be well for every city and town to establish by ord- inance, the grades of sidewalks, so as to avoid abrupt changes, excepting where ab- solutely necessary. Expansion Joints. If expansion joints are not provided, the walk is liable to heave up or cause disfigura- tion of the curb against which it is placed. Common practice now requires a ^-inch expansion joint at least every 50 feet. This is provided by a metal or wooden strip of the required width, which is allowed to remain in place until the walk has hardened, at which time suitable filler is poured into the opening. Figure 49 Cracking of sidewalk top due to expansion. The section on the right being better bonded, held to the base while the top on the adjoining section was pushed off figure 50 An abrupt change of grade that rise over the length of a slab. easily have- been prevented by extending the Universal Portland Cement Co. The practice of filling the joints with sand or earth is not recommended since such materials upon becoming dry and hard, cannot be pushed out by the expansion, and are little better than solid concrete. Clearance About Trees. When trees intercept the line of the walk, provision should be made for growth else the trees will crack the concrete, as illustrated in Figure 51. The amount of clearance around the trunk will depend somewhat on the age and kind of the tree, being greater for young trees, but should never be less than 6 inches at any point. Trees whose roots grow laterally, or near the surface of the ground, are more troublesome than those whose roots grow deeply. Root growth fractures slabs, and the destruction thus begun is completed by frost action. Cost The cost of cement walk will vary with the cost of materials and labor and with the experience of the men doing the work; also with the location of the walk, the amount of walk to be placed at one time and its width. Some notes based on actual experience relative to the cost of a walk will doubtless prove of interest. The cost of materials given below includes delivery on the work. Experience shows that a gang of six men can lay between 600 and 800 square feet of walk in a day of ten hours and 700 square feet is considered as a day's work in arriving at these figures. This estimate is based on a 6-foot walk, having 9-inch cinder sub-base, 4 /^^ nch ^ ase consisting of one part cement, 2^ parts sand and 5 parts crushed stone, covered with a %-inch top of 1 part Figure 51 Provision must be made for the subsequent growth of trees or else bad cracking will occur. S3- Concrete Pavements, Sidewalks, Curb and Gutter inch and contained 45 per cent voids. A good grade of coarse sand passing a J^-inch screen was used. The sand contained 33 per cent voids. The mixing was done by hand. LABOR (TWO-COURSE) One finisher at $.5.00 per day Five laborers at $.50 per day Total cost of labor (700 square feet) . Total cost of labor per 100 square feel. .$ 5.00 . 12.50 .$17.50 $ 2.50 MATERIALS (TWO-COURSE) Cement 2. 5 barrels at $1.50 per barrel Stone 1.21 cubic yards at $1. 50 per cubic yard Sand .80 cubic yards at $1. 25 per cubic yard Cinders 2.7 cubic yards at $0. 50 per cubic yard Total cost of materials per 100 square feet Total cost of laying 100 square feet 1.82 1.00 1.35 7.92 $10. 42 It should be noted that this estimate provides for a walk where an excavation for the sub-base was necessary, as shown in Figure 37. No addition was made for cost of forms or equipment depreciation. The cost of placing one-course work is probably less than for the two-course, but for comparison, the labor and cost of materials One-course jj ave been considered the same and the calculations made accordingly. sidewalk Figure 53 The effect produced by expansion is clearly shown above. The construction of the walk was first-class but for the omission of expansion joints. The break occurred in the center of the stretch approximately 200 feet long, abutting other and older walk at both ends. Universal Portland Cement Co. LABOR (ONE-COURSE) One finisher at $5.00 per day $ 5. 00 Five laborers at $2.50 per day 12. 50 Total cost of labor for 700 square feet $17. 50 Total cost of labor per 100 square feet $ 2. 50 MATERIALS (ONE-COURSE) Cement 2.42 barrels at $1.50 per barrel $ 3. 63 Stone 1.08 cubic yards at $1.50 per cubic yard 1. 62 Sand .73 cubic yards at $1.25 per cubic yard 91 Cinders 2.7 cubic yards at $0.50 per cubic yard 1. 35 Total cost of materials per 100 square feet $ 7. 51 Total cost of laying 100 square feet $10. 01 Concrete Sidewalk on Limestone Flags In some of the business districts of our larger cities, the old limestone flags are fast wearing out making replacement necessary. A great deal of expense may be saved, provided the flags are of sufficient thickness, by laying a mortar top, not less than 2 inches thick, directly upon the limestone. It is necessary to clean the surface thoroughly by chipping, and anchor a steel plate tp the flags for the curb edge. The application of a cement-granite screenings top completes the work, and has proven successful in several instances. Reinforced and Arch Walks. Attention is directed only toward pavements which are laid on the ground. For the construction of special types of sidewalk, detailed information is necessary for the work in question before any comprehensive analysis could be made or instruc- tions given as to the methods of undertaking. Sidewalk Calculations Number of cubic yards of concrete in 100 sq. ft. of sidewalk. 3 inch thick = 0. 926 3J/3 inch thick = 4 inch thick = 4 J4 inch thick = ty/l inch thick = 5 inch thick = .235 .312 .543 % inch thick = 0. 232 1 inch thick = 0. 309 Assuming 1 sack cement = 1 cubic foot, 1 cubic yard of concrete requires for: Mixture Bbls. Cement Cu. Yds. Sand Cu. Yds. Gravel 1:1^=3 -91 0.42 0.85 1:2 :3 .74 0.52 0.77 1:2 :4 .51 0.45 0.89 .31 0.48 0.87 .24 0.46 0.92 1:3 :5 .16 0.52 0.86 1:1 4.88 0.72 1:1H 3.87 0.86 Concrete Pavements, Sidewalks, Curb and Gutter Example: Two-course sidewalk 400 ft. long, 5 ft. wide, 4}^-inch base mixture 1:2} o:5, ?4-inch top mixture !:!}/. Area sidewalk 400 x 5=2,000 square feet. Base- Cubical contents 20.00 x 1.312=26.2 Cubic yards. ( x 1.24=32^ barrels cement 26. 2 j x 0.46=12 cubic yards sand [ x 0.92=24 cubic yards gravel Top- Cubical contents 20.00 x .232=4.64 cubic yards x 3.87=18 barrels cement x 0.86= 4 cubic yards sand 4.64 Total Example: ture 1:2:3. 18=50}^ barrels cement 12 + 4 = 16 cubic yards sand 24 + 0=24 cubic yards gravel One-course sidewalk as above 400 ft. long, 5 ft. wide, 4j^ inches thick, mix- Aiea sidewalk 400 x 5=2,000 square feet. Cubical contents 20.00 x 1,389=27.8 cubic yards !x 1. 74=48. 3. barrels cement x 0. 52=14. 5 cubic yards sand x 0. 77=21. 4 cubic yards gravel Figure S3 The possibilities of concrete curb in the garden are here very beautifully illustrated. The curb not only forms a pleasing framework for the flowers but provides for path as well. Universal Portland Cement Co. Curb and Gutter Construction While a sidewalk has a uniform cross section, which is well recog- nized and established, the same cannot be said of the curb, or curb and gutter. Every municipality and every individual interested in local improvements sees the requirements differently. For instance, in Chicago, and in towns where the country is level, it is possible to main- tain a constant height to the top of the curb, allowing the gutter or street to take the pitch necessary for drainage. This construction would manifestly be impossible in Albany, X. Y., or other hilly cities. The uses of curb are not. confined to the pavement of city streets, but extend to the beautification of the lawn, the flower bed or the drive- way. Like other concrete con- struction, the curb blends well with its surroundings and adds a finish not obtainable in any other way. The greatest variation in different localities for curb and gutter construc- tion P robabl y occurs at crossings and at street corners. Figure 56 shows the standard curb con- struction at the corner and is departed from but slightly. The regulation curb and gutter is shown in Figure 57. It will be noticed that the gutter is brought up at the cross walk, so as to make the difference in level but slightly noticeable to the pedestrian. This idea has been carried further in Figure 59 by omitting the gutter, or rather making the gutter and curb coincident. This type requires an extra gutter outlet at each side of the corner cross walks, which is con- nected underground to the corner man- hole. Another idea for preventing injury to the curb through ex- pansion is illustrated in Figure 60, where the sidewalk is carried out even with the gutter. Although this design is said to or- FJgun 5 5_ showing careless Iginate in Chicago, expansion^ at the .right,^ the several towns in the Figure 54 Showing combination curb and sidewalk around a flower bed. b has been nexcusable in view of the knowledge of the expansion. Concrete Pavements, Sidewalks, Curb and Gutter West have been using it for some time.* In all the above designs, a generous expansion joint is required, since the curb, not being reinforced, cannot resist the side pressure occasioned by temperature changes in an abutting sidewalk. To provide for this expansion, without injury to the curb, the West Park Board of Chicago, uses the design shown in Figure 61, and A patent has been granted on this construction. 1 I 'ex pans/ f / "expansion Joint) Sidewalk "expansion Join f-J /'expansion jcmf Figure 56 Curb layout at crossing. Universal P ortland Cement Co. Jexpans ion joint f^ Sidewa/k 1 ' e / p an s ion Join t r A \Jojnts t /'expansion joint J ..1 Section A-A Curb and Gutter Section B-B Curb and Gutter Fj^ure 57 Curb and gutter at crossing. Portion of gutter raised to decrease change of grade be- tween sidewalk and street. Concrete Pa r e in en ts , Sidewalks, Curb a n d Guile r / concrete curb using metal forms. 63 Concrete Pavements, Side w a I k s, Curb and Gutter S* 6' ne.- plate Wib'lirpla 2^, Figure 63 Forms for construct- ing combined curbs and gutter. Figure 64 Forms for constructing com- bined curb and gutter at cross walk. from the face to the back form. As the concreting progresses, the face is plastered with a 1:1^2 mortar, ^ inch or more in thick- Filling ness. When the concrete has been rammed in at the top, the mortar should be continued over the top, floated and the corners rounded. As soon as possible the upper face form should be removed and the entire surface wood floated and trowelled. A good finish can then be secured by brushing, keeping the Finding K the brush up and down and over the top, which gives the most pleas- ing surface. When sufficiently hardened so that the concrete will not "cave," the Figure 65^Curb and gutter construction with wooden forms lower face forms showing the clamps for holding the face board against the metal should be removed ision or spacing plates. plates pulled out. The joint can be finished by running the jointing tool over the opening. With metal forms the operations are practically the same. In setting them up, it is customary to drive stakes in the ground, at the t I f junction points, upon which to rest the forms. The templates 15 act in the double capacity of providing for uniform sections and in holding the face and back rigid. Curb and Gutter Construction. In building combined curb and gutter, using wooden forms, stakes are first driven to which the back form is attached and held to the alignment of the finished grade of the curb; likewise the gutter form is placed. Cross forms should be provided similar to those used in sidewalk Universal Portland Cement Co. construction and placed about every six feet, being careful to mark their location on the side forms with wax crayon, since it is at these points Cross form ^ a t the surface joints must also occur. The cross forms 1S should be placed so as to provide drainage capacity in the gutter. For the purpose of checking the slope, an ordinary wooden mounted level with a nail driven into the bottom at one end, is recom- mended. The proper pitch can be regulated by the distance the nail projects. When the form is filled level, using the cross forms as a guide for the strike, the concrete should be rodded off toward the curb and tamped down. The curb division plates are next placed, and the face board plastered up on the in- side with at least % Division inch of I:l y 2 mortar , filling with concrete as the plastering progresses. When the concrete is all tamped in, the mortar is con- tinued over the top, rodded off, floated and the corners rounded at the back with the short radius edger, and at the face with the curb edger. As soon as possible the , .-* z.^-ss^t Clamps Should be loosened, Figure 66 Finishing concrete curb with brush. the face form removed and the top placed on the gutter, using wood or steel strips of the required Finishing thickness, placed perpendicular to the curb, for a guide in striking off the mortar. After removing the guide strips, the depression left should be filled in with mortar, and the whole surface finished using the brush as previously described. The gutter rounding tool furnishes the proper corner section between the gutter and curb. A radius of at least !}/ inches is necessary at this point to prevent wagon wheels from striking the curb corner, since in the combined curb and gutter construction, batter is not generally given to the curb face. With metal forms the curb and gutter construction is similar to the work with wooden forms, except that stakes are driven for the forms to rest upon, and since the template forms the joint, no cross forms are required, and as the templates are generally wedged in from the outside, no clamps are necessary. The templates are withdrawn after the forms are taken away thus providing perfect joints between adjacent sections, and making expansion joints unnecessary. For building the conventional drains at the cross walk, the elevation Drains ^ ^ e S u tter is made by carrying up the gutter front form to the proper height, and using additional division plates and clamps as indicated in Figure 64. Concrete Pare m e nt .v , >S idewalks, Curb and Gutter In some cities, instead of plastering the form with a facing mortar, as described, the concrete is deposited directly against the form which is then removed; a dry mix of one part cement to lj/2 parts fine aggre- gate a little finer than is used in the other facing is then thrown * n ^ ie corner * the g utter - This dry mixture, if it does not take up enough moisture from the facing material on the gutter, is sprinkled with water thrown on with a brush, and then worked up or plastered over the face of the curb. This method, while faster than the one recommended should be discouraged as it will not give good results for the reason that the use of the rich dry mixture on the surface causes excessive hair checking and in addi- tion provides only a very thin wearing surface on the curb face. ON E- C OURSE WORK. It is very probable that like the one-course sidewalk and street pavement, the one-course curb and curb and gutter is practicable and should be encour- Fi/fure 67 Showing the need for proper expansion joints. The aged. This COnstrUC- failure in this case is not due m any way to the defective quality .. ,, ,. . of the concrete in the curb. tlOIl WOUld eliminate Figure 68 The wisdom of providing proper joints between curb and gutter sections is illustrated above where a wash into an old catch basin caused undermining of the foundation. With but little difficulty the foundation was re prepared and the sections replaced intact. Universal Portland C e m ent Co. a large amount of labor in plastering the forms and in placing the wearing surface. A special tamper would be necessary in separating the mortar similar to one-course sidewalk construction. The mixture used would be proportioned about 1:2:3. With metal face plates the surface could be obtained satisfactorily by tapping the form, thus bringing out the mortar without any spading. Expansion Joints. Provision for expansion joints should be made in building curb, and curb and gutter, as well as sidewalks, but as the exposure is not so great, fewer joints will probably answer. A complete joint 1/2 mcn wide, every 150 feet is probably sufficient for the average conditions. Care should always be c exercised to pro- vide a joint on a line with the edges of an abutting side- walk. No appre- ciable width is necessary, but such provision will guard against the curb being broken down by sidewalk expansion. The COSt of Figure 69 The expansion here amounted to 2 % inches but Kiiilrlincr riirh ftr\t\ owing to the construction, the curb was not broken. If proper lliamg CUrD ana expansion joints had been provided this could not have occurred Combined CUrb and but the picture demonstrates clearly that with this construction gutter depends, of no harm has been donc either to the sidewalk or the curb - Figure 70 Expansion joints are necessary in curb and gutter as well as in roadways and sidewalks and when proper provision for expansion is not made, heaving is very liable to occur, as illustrated. Concrete Pave m e n t s , Sidewalks, Curb and Gutter course, upon the cross-section and proportions used. Since the variation in the cross section is large, it is difficult to figure upon actual costs, but from data obtained at Gary, Indiana, the labor item for curb construc- tion would be about 11-12 cents per lineal foot. In constructing curb and gutter at Webb City, Mo., the cost of labor totaled about 13 cents per lineal foot. In both cases the finisher netted about $5.00 per day, and the laborer $'-2.50 per day. On this basis the cost of curb construction would be as follows for the section shown in Figure 56, page 58. LABOR 100 lineal feet curb $11. 50 MATERIALS Cement 7. 8.5 barrels at $1. 50 per barrel $11. 80 Sand 2. 70 cubic yards at $1. 25 per cubic yard 3. 40 Stone 4. 79 cubic yards at $1. 50 per cubic yaid 7. 20 Cinders 1 . 85 cubic yards at $0. 50 per cubic yard 95 Total cost of materials per 100 lineal feet $23. 35 Total cost of laying 100 lineal feet $34. 85 Assuming the labor on combined curb and gutter at 13 cents per lineal foot for constructing the section shown in Figure 57, page 59, the cost would be as follows: LABOR 100 lineal feet curb and gutter $13.00 MATERIALS Cement 7. 78 barrels at $1. 50 per barrel $11. 70 Sand 2. 41 cubic yards at $1. 25 per cubic yard 3. 10 Gravel 3. 55 cubic yards at $1. 50 per cubic yard 5. 35 Total cost of materials per 100 lineal foot $20. 15 Total cost of laying 100 lineal feet $33. 15 Where crushed granite is used the cost would generally be higher on account of the greater cost of materials. No provision has been made for cost of forms or depreciation on equipment. Universal Portland Cement Co. Commercial Forms Concrete for sidewalks, curb, and curb and gutter is generally molded by means of wooden forms. The contact of wet concrete however, tends to warp the wood out of shape, besides the nailing and staking necessary in setting them up makes removing difficult without danger of breaking or splitting, which shortened the life of the forms. The skilled labor necessary, time required in setting, and cost of lumber for this work, makes these items enter largely into the cost of the job. Metal forms of various types have been designed to overcome this problem by secur- ing greater durability of forms, more uniform work, besides saving labor, cost and time required to complete the work. A number of commercial foims now on the market are briefly illus- trated and described in the following pages. The Berger Manufacturing Company of Canton, Ohio builds sets of all steel forms for concrete sidewalk, curb, and curb and gutter construc- tion, which consist of side rails, 4, 6 and 10 feet in length and division plates or templates, varying in length from 2 to 8 feet, made "of pressed steel. Figure No. 75 shows the sidewalk forms set up. The flange construction and the slip joint which er manu Berg facturing Co. I up. connects the side rails end to end, gives sufficient strength to prevent the forms from springing out of shape when the concrete is being placed and finished. The edges of both upper and lower flanges of the side rails are rounded to permit of rapid handling without danger of Sidewalk cut ting the hands. The side rails are gauged to the width of the walk by means of the steel division plates, having lugs at the ends which project through the openings in the side rails in a manner Figure 71 General view of concrete curb and gutter construction showing the workman tamping the curb in the foreground. -69- ( ' o n c r e t c 1> a v e m ents , Side u* alks, Curb and Gutter Figure 73 Berger steel curb forms. Figure 72 Detail of Berger lock joint. Figure 74 Berger steel forms for combined curb and gutter. Figure 75 Berger steel sidewalk forms. to be fastened securely by means of a spring wedge. Flexible side rails 4, 6, 8 and 10 feet in length, with slots to hold the division plates, are provided for building curved sections. Curves of 6-inch Crosswalk Til( \[ us are use d to round corners and make intersections where it is desired that these be rounded. For crosswalk construction, a rigid 5-foot side rail is used with a template curved to form a crown to the crosswalk. Figure No. 73 makes clear how this principle is applied to concrete curb work by use of templates of the same shape as a cross section of C b f rms *^ ie ^ n ' sne ^ curb. The curb stands 18 inches in height, 6 inches in width at the top and 9 inches at the bottom. A batter 1 1/2 inches on both sides facilitates the removal of the plates and gives added strength. The edges of the curb are rounded to 1 inch radius. The style of curb and gutter shown in Figure 74 provides for a curb 12 inches in height, 6 inches thick and with the gut- Curb and ter gjjg 7 i^ j nc h es high. The gutter is 19 inches wide and * dips toward the curb \Y 2 inches. The back of the curb is Universal Portland Cement Co. made with a batter of 1 inch to 12 inches, which assists in the im- mediate removal of the forms without waiting for the concrete to harden thoroughly. The steel templates are the same shape as a section taken through the finished curb and gutter. From the sides of these templates, lugs extend, and to these lugs are fastened the side rails as shown by Figure 72. Three 4-inch side rails, the same as those used in sidewalk construc- tion, are required for the back and a special 7^/2-inch rail for the front or gutter side of the curb, while one 6-inch side rail is required for the front of gutter. The sidewalk forms can be used with the curb and gutter or curb construction, which materially reduces the cost of the forms for any individual construction provided the builder can take either sidewalk or curb and gutter contracts. The sidewalk forms as shown in Figure 76 are composed of channels which are used to supplant the common 2 x 4's for side rails, and are built by the Blaw Steel Centering Company, Pittsburgh, Pa. These channels come regularly in 10-foot lengths and are joined together by quick acting slip joints. The side rails are built in various heights according to the thick- ness of the walk required. Every foot, the rails are slotted and the steel dividing plates insure correct expansion joints. The plates are made in any width or height required and can be removed either before or after the side rails. The curb and gut- ter forms are built of pressed steel side rails and Curb and steel gutter forms Figure 76 Blaw forms Crete sidewalk. in use building con- Sidewalk forms f * Figure 77 New York State road ing curb. g Blaw forms for build- 71 ing plates to conform to the shape of the finished curb and gut- ter. The back face of the curb is formed by bolting the side rails together to get the required height or by a single back rail. For the front face of the curb, a wooden form is Concrete Pavements, Sidewalks, Curb and Gutter used inasmuch as this strip is removed immediately after the concrete is placed in order to allow for finishing. Figure No. 77 gives a view of an equipment for speedy curb con- struction in use on the New York state road work. The curb forms are built in practically the same manner as the combined curb and gutter c and sidewalk forms. The side forms are made of one single rail or a number of rails bolted together to give the required height. As with the other forms, expansion joints are provided by means of dividing plates which are inserted in the slotted rail. These ex- pansion joints can be placed wherever specified. The division plates which are removed independent of the side rails or vice versa, are furnished for straight or battered curb. These forms can be specially designed where extreme sizes are necessary. The Heltzel steel forms are manufactured by Jones & Heltzel of Streator, Illinois, and are illustrated on the opposite page. The sidewalk forms are composed of rigid, adjustable, flexible, and curved side rails; also division plates or templates. Rigid side rails are made of an- H^ltzel nea ' et l stee l' pressed to shape in sections of 6, 9 and 12-foot lengths, with curvilinear openings in the top flange to receive the division plates at intervals of one foot. These rails are 4 inches deep with a lj^- inch flange on the bottom and a 2-inch flange on top, from which is a depending flange of one inch, and are connected end to end by a sleeve. Rigid adjustable side rails 5 feet long are arranged to telescope a Sidewalk t or th j f n i engt h w ith t he regular side rails. By their forms f . & . ,, ... use, forms can be set in any odd space without using wood to fill in. Flexible side rails made in 6, 8, 10 and 12 foot lengths, slotted at intervals of one foot for division plates, are for use in curved sections. Division plates ]/% inch thick and 2 to 8 feet in length, have tapering slots at their ends to make the forms easy to set up and take down. Directly under each slot in the side rails is stamped a protu- berance which serves to engage the division plate firmly with the side rail when placed in position This device permits the template to be re- moved without dis- turbing the side rails. Figure 78 shows forms for the con- struction of com- Fi&ure 78 Heltzel forms for buildinj combined sidewalk and cui;b. 1) i n a t i O n S i d 6 W a 1 k Universal Portland Cement Co Figure 79 Heltzel forms in use for constructing combined curb and gutter. Figure 80 Heltzel Sidewalk Forms. Concrete P a r e m e nt .v , . Finishing Tools 24 -inch trowel, edger and jointer with long handles, one pair of compasses, an interchangeable short emergency handle and wrench. for the concrete the market with Figure 87 Andrews concrete Arrowsmith long-handled concrete finishing The trowel blades are made of 21 -gauge steel at- tached to a malleable iron T , mounting. The long handle is connected directly to the mounting and can be adjusted to any angle the operator may desire. The edgers and jointers are made of bronze and malleable iron provided with the same style of handle as described with the trowel. These are molded with both Edger and edges raised to aid jointer in securing a clean joint and edge. Univers al P ort land Cement Co. Compasses The compasses have a spread of 6 feet. When closed the guide blade lays along the side of the arm like the blade of a pocket knife, thereby taking up no unnecessary space. The Concrete Supply Company, Arrowsmith, Illinois, make The Concrete Supply Co.'s lon g handled trowels, edgers, groovers and Long Handled Tools tampers; also the strike-off shown in Figure 89. Figure 89 Long handled concrete finishing tools, manufactured by the Concrete Supply Co. The trowels are manufactured in 20-inch and 24-inch lengths. They are made of tempered steel with riveted malleable rib. Each trowel is equipped with an adjustable, interchangeable handle. The edger and jointer are made in both iron and bronze. These tools are provided with an adjustable handle similar to that of the trowel and have a rocker shaped face which prevents the point r , _, . . . from plowing up the concrete in front. By the use of Eager and jointer , . \ ,, te .f . . . j^. . , short handles the complete set is converted into regular short -handled tools. Compasses are made of malleable iron, highly finished with the sides channeled out to cut down the weight. They are built to .~ have a spread of any width up to six feet, and are intended Compasses . * , " , , r lor use in laying out the work. The tamps are made of cast iron with ll"xll" face, with both Tamps plain and corrugated bottoms. The corrugated faces are intended to avoid the suction experienced with flat bottomed tools. The Heltzel Rotary Float shown in Figure 16, consists of a flat, round disc-like blade attached to a long handle by means of tary Float a J omt ' wm ch permits operation with a rotary motion. The blade is supplied in soft wood or in steel. The finishing trowel shown in Figure 91 is manufactured by the Twentieth Century Manufacturing Company, Chicago Heights, Illinois. aremcnts, Side tr alks, Curb and Gutter Figure 90 Heltzel Rotary Float. Trowel Twentieth Century The trowel has a steel blade 24 inches long, 5 inches Long Handled Tools wi( j e> attac h e d to the handle by means of a tilt motion device for raising the edge of the blade. As the workman pulls the trowel, the forward edge is auto- matically raised up to prevent the edge from dig- ging into the mor- tar, then as the work- man pushes the trowel, this action is reversed and the other edge of the blade is raised. The device enables the operator to do the work without raising or lowering the handle. The jointer is a 16- Jointer . ., ..',,. the Same tilting Figu re 91 Automatic finishing trowel made by the Twentieth Cen- tury Manufacturing Company. Universal Portland C e m ent Co Edger device as the trowel. A joint casting which will slip on and fasten to the trowel or jointer blade is of the proper design to cut a joint of the correct size and shape. The edger has a blade 10 inches long by 3^2 inches wide, and is rounded on one side to give the correct curve to the edge. While means for protecting the fresh- ly laid concrete cannot be classed directly under special tools, yet the appearance of the work depends Lantern holders and l arge l y upon keeping woven wire standards . 7e i i traffic and animals from the work until hardened. The Anderson Tool and Supply Co., Detroit, Mich., makes a specialty of the supports illustrated in Figure 92. Figure 92 Lantern and wire holders.. .J: Figure 93 An inspection party starting out to tour the concrete roads of Wayne County, Michigan. 81 Concrete Pavements, Sidewalks, Curb and Gutter Proposed Revised Standard Specifica- tions Concrete Roads and Street Pavements Presented to the National Association of Cement Users December, 1912 Materials 1. CEMENT. The cement shall meet the requirements of the Stand- ard Specifications for Testing Materials, and adopted by this Associ- ation (Standard Xo. 1). 2. FIXE AGGREGATE FOR CONCRETE. Fine aggregate shall consist of sand, crushed stone or gravel screenings graded from fine to coarse and passing when dry, a screen having one-quarter (J4) inch diameter holes; shall be preferably of silicious material, clean, coarse, free from dust, soft particles, loam, vegetable or other deleterious matter, and not more than three (3) percent shall pass a sieve having one hundred (100) meshes per linear inch. Fine aggregate shall be of such quality that mortar composed of one (1) part Portland cement and three (3) parts fine aggregate, by weight, when made into briquettes, will show a tensile strength at least equal to the strength of 1 :3 mortar of the same consistency made with the same cement and Standard Ottawa sand. In no case shall fine aggregate containing frost or lumps of frozen material be used. 3. AGGREGATE FOR WEARING COURSE. The aggregate shall consist of screened gravel or stone screenings from granite or other close- grained durable rock, sufficiently hard to scratch glass, free from loam or other deleterious matter, mixed in the proportion of three (3) parts passing a one-half (J/0 inch ring and retained on a screen having one- quarter (^) inch diameter holes and two (2) parts passing a screen having one-quarter (J^) inch diameter holes and retained on a screen having fifty (50) meshes per linear inch. In no case shall aggregate for wearing course containing frost or lumps of frozen material be used. 4>. COARSE AGGREGATE FOR CONCRETE. Coarse aggregate shall consist of inert materials such as stone or gravel, graded in size, retained on a screen ha ving one-quarter ( l /) inch diameter holes ; shall be clean, hard and durable, free from dust, vegetable or other deleterious matter, and shall contain no soft, flat or elongated particles. In no case shall coarse aggregate containing frost or lumps of frozen material be used. The maximum size of the coarse aggregate shall be such as to pass a one and one-half (1^/2) inch ring. 5. NATURAL MIXED AGGREGATES. Natural mixed aggregates shall not be used as they come from deposits, but shall be screened and remixed to agree with the proportions specified. Universal Portland Cement Co. 6. SUB-BASE. Only clean, hard, suitable material, not exceeding four (4) inches in the largest dimensions, shall be used. 7. WATER. Water shall be clean, free from oil, acid, alkali, or vegetable matter. 8. COLORING. If artificial coloring matter is required, only mineral colors shall be used. 9. REINFORCING METAL. The reinforcing metal shall meet the requirements of the Standard Specifications for Steel Reinforcement adopted March 16, 1910 by the American Railway Engineering Associa- tion. Sub-Grade 10. SECTION. The sub-grade shall have a rise at the center of not more than one-hundredth (1-100) the width of the pavement. 11. DEPTH, (a) The sub-grade shall not be less than twelve (12) inches below the finished surface of the pavement. (b) The sub-grade shall not be less than six (6) inches below the finished surface of the pavement. 12. PREPARATION. All soft and spongy places shall be removed and all depressions filled with suitable material which shall be thoroughly compacted in layers not exceeding six (6) inches in thickness. 13. DEEP FILLS. When a fill exceeding one (1) foot in thickness is required to bring the pavement to grade, it shall be made in a manner satisfactory to the engineer. 14. DRAINAGE. When required, a suitable drainage system shall be installed and connected with sewers or other drains indicated by the engineer. NOTE. When a sub-base is required, eliminate Paragraph 11-b. When sub-base is not required, eliminate Paragraphs 6, 11-a, 15 and 16. Unless 11-a is eliminated, 11-b is void. 15. THICKNESS. On the sub-grade shall be spread a material as hereinbefore specified, w r hich shall be thoroughly rolled and tamped to a surface at least six (6) inches below the finished grade of the pave- ment. 16. WETTING. While compacting the sub-base, the material shall be kept thoroughly wet and shall be in that condition when the concrete is deposited. Forms 17. MATERIALS. Forms shall be free from warp and of sufficient strength to resist springing out of shape. 18. SETTING. The forms shall be well staked or otherwise held to the established lines and grades and their upper edges shall con- form to the established grade of the pavement. 19. TREATMENT. All wood forms shall be thoroughly wetted and metal forms oiled before depositing any material against them. All mortar and dirt shall be removed from forms that have been previously used. Expansion Joints 20. WIDTH AND LOCATION. Expansion joints not less than one- quarter (34) inch nor more than one-half (^) inch in width shall be Concrete Pavements, AA^&Ail --- ^" "'A*'" 4 1?*.4~*. Figure 94 Standard Curb Section. Figure 95 Standard Curb and Gutter Section. 20. SECTION AT STREET CORNERS. The construction of the com- bination curb and gutter at street corners shall conform with that shown in Figure 3. The radius of the curb shall not be less than six (6) feet. 21. WIDTH AND LOCATION OF JOINTS. A one-half (^2) inch expan- sion joint shall be provided at least once in every one hundred and fifty (150) feet. 22. JOINT FILLER. The expansion joint filler shall be a suitable, elastic, waterproof compound that will not become soft and run out in hot weather, nor hard and brittle and chip out in cold weather. 23. PROTECTION OF EDGES. Unless protected by metal, the upper edges of the concrete shall be rounded to a radius of one-half (J^) inch. Measuring and Mixing 24. MEASURING. The method of measuring the materials for the concrete, including water, shall be one which will insure separate uni- form proportions at all times. A sack of Portland cement (94 Ib. net) shall be considered one (1) cubic foot. 25. MACHINE MIXING. WTien the conditions will permit, a machine mixer of a type which insures the uniform proportioning of the materials throughout the mass, shall be used. The ingredients of the concrete or mortar shall be mixed to the desired consistency and the mixing shall continue until the cement is uniformly distributed and the mass is uniform in color and homogeneous. 26. HAND MIXING. When it is necessary to mix by hand, the mater- ials shall be mixed dry on a watertight platform until the mixture is of uniform color and the required amount of water added, and the mixing continued until the mass is uniform in color and homogeneous. 27. RETEMPERING, that is remixing mortar or concrete that has par- tially hardened with additional water, will not be permitted. Two- Count Curb and Curb and Gutter Btue 28. PROPORTIONS. The concrete shall be mixed in the proportion of one (1) sack Portland cement, two and one-half (2^) cu. ft. fine aggregate, and five (5) cu. ft. coarse aggregate. 29. CONSISTENCY. The materials shall be mixed wet enough to produce a concrete of a consistency that will flush readily under slight U nirersal Portland Cement Co. tamping, but which can be handled without causing a separation of the coarse aggregate from the mortar. 30. PLACING. After mixing, the concrete shall be handled rapidly and the successive batches deposited in continuous operation completing individual sections. Under no circumstances shall concrete be used that has partially hardened. The gutter forms shall be filled and the concrete struck off and tamped to a surface the thickness of the wearing course below the established grade of the gutter. The concrete for the curb shall be placed and tamped so as to permit of the application of the required wearing course to the face and top so as to bring the work to the established line and grade of the curb. The work shall be executed in a manner which will insure perfect joints between abutting sections. Workmen shall not be permitted to walk on freshly laid concrete, and if sand or dust collects on the base, it shall be carefully removed before the wearing course is applied. Wearing Course 31. PROPORTIONS. The mortar shall be mixed in the manner herein- before specified in the proportion of one (1) sack Portland cement and not more than two (2) cubic feet of fine aggregate. 32. CONSISTENCY. The mortar shall be of a consistency that will not require tamping but which can be easily spread into position. 33. THICKNESS. The wearing course of the gutter and top and face of the curb shall have a minimum thickness of three-quarters (^) of an inch. 34. PLACING. The wearing course shall be placed immediately after mixing, and in no case shall more than fifty (50) minutes elapse between the time the concrete for the base is mixed and the time the wearing course is placed. 35. FINISHING. After the wearing course has been brought to the established line and grade, it shall be worked with a wood float in a manner which will thoroughly compact it. When required, the surface shall be troweled smooth, but excessive working with a steel trowel shall be avoided. The section markings shall be made in the wearing courses directly over the joints in the base with a tool which will com- pletely separate the wearing courses of adjacent sections. If excessive moisture occurs on the surface, it must be taken up with a rag or mop, and in no case shall dry cement or a mixture of dry cement and sand be used to absorb this moisture or to hasten the hardening. The edge of the curb on the street side and the intersection of the curb and gutter shall be rounded to a radius of about one and one-half (1^) inches. All other edges shall be rounded to a radius of three-eights (^) inch unless protected by metal. 36. COLORING. If artificial coloring is used, it must be incorporated w r ith the entire wearing course and shall be mixed dry with the cement and aggregate until the mixture is of uniform color. In no case shall the amount of coloring used exceed five (5) percent of the weight of the cement. ( ' o n c r c t c P a v e m e n 1 .v , N / d e w a I k s , Curb and Gutter One- Course Curb and One- Course Curb and Gutter The general requirements of the specifications covering two-course work will apply to one-course work, with the following exceptions: 37. PROPORTIONS. The concrete shall be mixed in the proportion of one (1) sack Portland cement and not more than two (2) cubic feet of fine aggregate, and three (3) cubic feet of coarse aggregate passing a one (1) inch ring. 38. PLACING AND FINISHING. The forms shall be filled, the concrete struck off and the coarse particles forced back from the surface, and the work finished in usual way. Protection 39. TREATMENT. As soon as the concrete has hardened sufficiently to prevent being pitted, it shall be sprinkled with clean water and kept wet for at least four (4) days. The work shall not be opened to traffic until the engineer so directs. 40. TEMPERATURE BELOW 35 F. If at any time during the progress of the work, the temperature is, or in the opinion of the engineer v M l within twenty-four (24) hours drop to thirty-five (35) degrees Fahren- heit, the water and aggregates shall be heated and precautions taken to protect the work from freezing for at least five (5) days. In no case shall concrete be deposited upon a frozen sub-grade or sub-base. UNIVERSAL PORTLAND CEMENT CO. Offices- Chicago 72 West Adams Street Pittsburgh - - Frick Building Minneapolis Security Bank Building Plants at Chicago and Pittsburgh Annual Output 48,000,000 Sacks UNIUUHU A 000036588 2 Al