m^mm 7z3 73^ UC-NRLF ^B 25 E3E Xijc:. OJTii •^iner ...iebr i ^. ,-- £ % _ - . ^ t . ..::r± . •-/ w. 11. juxl -oi, 1^. i-Oi' ti^n)'. ,\'.?:i;. l^lij-'i^y Bulletin 16] f'ORfl'pjj^ The Agricultural Experiment Station OF THE Colorado Agricultural College CEMENT AND CONCRETE FENCE POSTS BY H. M. BAINER H. B. BONEBRIGHT PUBLISHED BY THE EXPERIMENT STATION FORT COLLINS. COLORADO 1910 .^^ ,t :e)^ The Agricultural Experiment Station FORT COLLINS, COLORADO THE STATE BOARD OF AGRICULTURE Term Expires Hon. B. F. ROCKAFKIyl^OW, Canon aty, 1911 Hon. K. H. GRUBB, Carbondale, 1911 Hon. R. W. CORWIN, Pueblo, 1913 Hon. a. a. EDWARDS, President, ... - Fort Collins, 1913 Hon. F. B. BROOKS, Colorado Springs, 1915 Hon. J. Iv. BRUSH, Greeley, 1915 Hon. J. C. BEIvIv, Montrose, 1917 Hon. E. M. AMMONS, Ivittleton, 1917 Governor JOHN F. SHAFROTH ) ^^ nm^-:^ Prrsidsnt CHAS. a. IvORY ^ \ ^^-^i^icio. I^. M. TAYIvOR, Secretary G. A. WEBB, Treasurer J. ly. BRUSH, EXECUTIVE COMMITTEE IN CHARGE. A. A. EDWARDS Chairman. E. M. AMMONS STATION STAFF I^. G. CARPENTER, M. S., Director, - - - Irrigation Engineer C. P. GIIylvETTE, M. S., Entomologist W. P. HEADDEN, A. M., Ph. D., Chemist G. H. GLOVER, M. S., D. V. M., Veterinarian ALVIN KEYSER, A. M. Agronomist J. O. WIIvLIAMS, B. S. A., U. S. Expert in Charge - Horse Breeding W. G. SACKETT, B. S., Bacteriologist E. R. BENNETT, B. S., Horticulturist P. K. BIvINN, B. S., Rocky Ford - - Field Agent, Arkansas Valley R. E. TRIMBLE, B. S., ... Assistant Irrigation Engineer F. C. AIvFORD, M. S., Assistant Chemist EARIv DOUGLASS, M. S , - - - - Assistant Chemist S. ARTHUR JOHNSON, M. S., - - - • Assistant Entomologist B O. LONGYEAR, B. S., ASSISTANT Horticulturist MIRIAM A. PALMER, Delineator L. C. BRAGG, Ass'T in Entomology C. L. FITCH, Potato Investigations H. M. BAINER, M. S., ... . Dairying and Farm Machinery G. E. MORTON, M. L., B. S. A., - - - - Feeding Investigations G. C. KREUTZER, B. S., . - - Ass'T Irrigation Investigations GEORGE P. WELDON, B. S., Grand Junction. - Field Entomologist R. S. HERRICK, B. S., Delta, .... Field Horticulturist W. E. VAPLON, Poultry J. E. PAYNE, .... . . Field Agent, Plains J. W. ADAMS, Cheyenne Wells, .... Sup't Sub-Station JAMES HUTTON, . - . Groom MATERIALS USED IN CONSTRUCTING, j^m^'^ AND CONCRETE FENCEF'P^ST^AunjfaMt^ By H. M. BAINER and H. B. BONEBRIGHT PART I. GENERAL STATEMENTS Cement. — In cement fence post construction, it is desirable that the post be made as li^ht and as strong as possible, and thus it is practical to use nothing but the best grade of Portland cement. Sand. — Clean, sharp sand with grains varying in size from small to large makes the best mixture. Sharp sand- is composed of sharp, angular grains of all sizes and makes a better mixture than that which is smooth and round, or "river-worn." A sand composed of fine and coarse grains mixed, is to be preferred, because less cement will be required to fill the voids than either used by itself. Leaves, sticks, stones or gravel should be removed by screening. Gravel. — The same general rules used in the selection of a good grade of sand will apply to gravel. It should be composed of clean, sharp pebbles of all sizes. For post construction, the pebbles must not be too large, as they will interfere with the proper placement of reinforcement. Broken Stone. — Broken stone used for post construction must contain no large pieces as they will interfere with the place- ment of the reinforcement. It is necessary to use sortie sand with the stone to fill voids and thus save cement. It is not desirable to use soft sandstone, soft limestone, slates, or shales. Granites, hard limestones, and coarse gravel, which has been crushed, is considered best. Water. — The water used in making a cement or concrete mixture should be clean and free from alkali or acids. Proportions. — On account of the difference in the total open space or voids in sands or gravel composed of different sized particles and also that more cement is required in some conditions than in others, it is often necessary to make a rough determination of the percentage of voids to the total aggregate. Where maximum strength is required about lo per cent, more cement should be used than the total voids. The determination may be made as follows : Secure a water- tight box or pail of known capacity, fill it with the aggregate to be used so that when it has been well shaken it will smooth off even * This bulletin is an abbreviated edition of Bulletin No. 148 of June, 1909. A large part of the details of the tests have been omitted, but all the important results are summed up in the tables here presented. 496123 4 The C01.ORAD0 Experiment Station at the top. Pour water of known amount into this until full. The volume of water used in proportion to the total volume of the receptacle determines the total voids. The proportions used in the constructions of the fence posts in this bulletin varied from i part cement and 3 parts of sand to I part of cement and 5 parts sand. In others, gravel was used in the proportion of i part cement, 3 parts sand, and 3 parts gravel. It is a difficult matter to use broken stone or gravel in large quan- tity and place the reinforcement properly. Measure all materials in correct proportions. This may be done with a shovel, a pail, wheelbarrow, or barrel. It will usually be advantageous to measure the water, especially where small quan- tities are mixed or where the same amount of mixture is made sev- eral times. Mixing. — Where the mixing is done by hand, a flat, water- tight platform, or shallow box is convenient. Measure the sand and place it in a uniform layer and over this spread the proper amount of cement. Mix this thoroughly before adding water until it shows a uniform color. The rule is to shovel it over at least three times. Now spread out the mixture, making a sort of basin in the middle into which the greater part of the water may be poured. Work in the dry edges until the water disappears, then add enough more water in small amounts to make the mixture of the desired consistency. Do not mix more material than can be used in twenty minutes. Poured Posts. — There are two general classes of mix- tures which may be used in the construction of posts ; the poured and the tamped. In the poured mixture, enough water is used in mixing to make it thin enough to pour from a pail or scoop almost like water. The mixture is poured into a mold and allowed to re- main in it until it has set, which is from one to five days, depending upon the time of year and the weather. In drying summer weather, from one to two days is usually sufficient. In cool or damp weather, they must be left in the molds much longer. In order to make several posts of the poured type at once, it is necessary to have several molds ready for use. With 6 molds only 6 posts could be made at once, and it would be necessary to wait until the cement was set before 6 more could be made. It was found that to make a good poured post, the mixture should be stirred or shaken immediately after placing in the mold. This should be done carefully to prevent displacement of reinforce- ment wires. This helps to remove the air from the mixture and makes a post of smooth finish. The experiment showed that a poured post of a certain mix- ture was stronger than a tamped post of the same mixture. It is Cement and Concrete Fence Posts. 5 enough stronger to justify anyone in constructing it in preference to the tamped one at the necessary additional expense for molds. The poured post is smoother, more nearly impervious to water, not so hard to cure, stronger, somewhat more expensive, and can be better recommended than the tamped one. Tamped Posts. — The tamped post is one in which the mixture contains very much less water than the poured one. It contains just enough water to make it hold together well when tamped. In the manufacturing of this type of post, only one mold is necessary. The mixture is tamped into it, and the sides of the mold can be removed immediately, the post remaining on the bot- tom piece until the cement has set. Thus the same mold can be con- tinuously used for making as many posts as are desired. The ne- cessity for but one mold makes this type of post less expensive than the poured one. The results of the test made, show that the tamped post is inferior to the poured one and cannot be placed in an equal class with it. On account of less water being used in the mixture for a tamped post than in the mixture for a poured one, the tamped post reqtiires more water and attention in curing. It is of more open texture, less impervious to water, not as strong, and not as desir- able as the post of the poured type. Molds For Tamped Posts. — In this class of molds we find mostly the heavy cast-iron forms which are built of strong and heavy material. The most of these molds are designed to be laid upon pallettes or upon a smooth floor. The mixture is first tamped into the mold to a depth of about one inch. The reinforce- ment is then placed and the mold is next filled, and the mixture tamped, so that only about one inch, of material remains to be filled in. The second set of reinforcement wires is put in place next and the mold is tamped full to overflowing. The last step con- sists in smoothing off the top of the post with a trowel and re- moving the mold. This is done by unfastening some form of hook or clasp, slipping the sides of the mold a little distance away from the post, and then removing the molds to the position chosen for the next post. The principal advantage of these molds lies in the fact that they being made of heavy iron need no center stays. This gives greater speed in operation, due to the fact that there are no cross pieces to interfere with the placing of the reinforcement, the tamp- ing of the mixture, and the smoothing off of the top of the post at the finish. Molds for Poured Posts. — The more common forms are made of sheet iron, either galvanized or plain. For posts having a continual taper from top to bottom, sheet iron molds prove very 6 The Colorado Experiment Station satisfactory, providing sufficiently heavy material is used in their construction. The advantages of the sheet iron mold are many. They are light to handle and easy to keep clean. If properly made they are nearly water tight. This insures the user against the possible loss of cement by leakage. Another marked advantage of the sheet-iron mold is that the surface being smooth, imparts a very smooth, //OA/£AfAJ?£MOLD/-OR F/V£ /A/CH POST % -tf//-. 4 rf swrorMOLD. Mr«)£ V/EW. eNOMec£s. BAS£. TOP. fMt. rr-HOL£Pifi. cnoMco ^MOUMD. fAST£N£/iS. BASE. CBOVND TOP. \fpWND. ^fpoi/j^o\Aoia fAOiWD. rOPATCr P/lfV, (TLONCi ^{AOOMf. MOLD ASS£MBL£D. S/D£ V/£W. Figure I. A Home Made Mold Giving the Proper Shape to the Post. — 1. Base fastener. 2. Base end piece. 3. Ground line fastener. 4. 4, etc. Tie hole pins. 5. Top piece pin. 6. Top end piece. 7. Top fastener A. Side of mold. B. Pallette. I glossy finish to the surface of the post. This not only adds beauty to the post, but aids in keeping out water, which might otherwise enter the cured post. As the sheet-iron molds are made in one piece, no pallette is necessary. In hot weather the post may be removed after 48 hours, but in cold weather a much longer time is required. Cement and Concrete Fence Posts. 7 In making poured posts in these molds exactly the same pro- cess is followed as with tamped posts in molds of the first class just described ; with the exception that the mixture is not tamped and greater care must be exercised in preventing the reinforcement from being misplaced. Some forms of wood molds are made and used for the purpose of making poured posts only. Any desired form may be given to the post by properly shaping the mold. This point, in favor of the wood mold, is an extremely important one, as it permits the post to be made of uniform size from the bottom to the ground line, but with a rapid taper from this point to the top. Then too, the sides of the mold may be removed after 24 hours and used again in con- nection with other pallettes; while the post which has not yet be- come sufficiently strong to be removed from the pallette lies un- molested in its original place until it is ready to move. Molds which may be used for making either the tamped or the poured posts are much the same as the wooden molds for poured posts, except that they are stronger. The heavy, cast-iron molds could be used in making the poured posts as well as the tamped ones, but their original cost make them impracticable. The wooden molds serve the purpose equally well and are much cheaper. Selecting the Mold. — The most important point to be con- sidered in selecting the mold is the shape and size of it. Next to the shape and size we should look for ease of operation. The simple mold almost always proves to be the best, providing it has sufficient strength. Care of Molds.^Beiore the- molds are used they should be well coated with some kind of heavy oil. Crude petroleum is perhaps the best and cheapest material for this purpose. In case the petroleum cannot be obtained, a good oily mixture may be made by stirring about two pounds of axle grease into a gallon of gaso- line. This mixture is applied to the molds with a brush. The gasoline evaporates, leaving a thin coat of axle grease spread over the entire surface of the mold. This oily mixture should be ap- plied to the outside as well as the inside of the mold, which makes it impossible for any of the material to cling to it. With the iron molds, the oil prevents rusting. In case the molds are made of wood, the oil helps to keep out the moisture, thus preventing shrink- ing and swelling, and also making them easier to keep clean. As soon as the mold is removed from the post all material sticking to it should be scraped off and the inside surface covered with a thin coating of oil. Great care should be taken not to allow the molds to become bruised or dented. If the molds are not to be used for a time, they should be thoroughly scraped and oiled, inside and out, and carefully laid away. 8 The Colorado Experiment Station Reinforcement. — Cement and concrete work has the prop- erty of resisting great, crushing stresses, but when subjected to tensile stress the best of it breaks very easily. For this reason it becomes necessary to put some material possessing great tensile strength into the post, in order that the full crushing strength of the cement or concrete may be utilized. Iron is the most satis- factory material from which to make reinforcement. The rein- forcement should be placed in the post as near the corner as pos- sible. This places it as far as possible from the neutral axis thus giving it the greatest advantage in strengthening the post. In order that the reinforcements may be properly held and protected by the cement, it is a good plan to place it from ^ to ^ inch in from each side. The material used for reinforcement should be strong, light and rough enough to permit the mixture to get a firm grip upon it. It should be very rigid, with little or no tendency to spring or stretch. The experiments showed that ordinary iron or steel wire was cheapest, strongest and easiest to procure. In order to provide a means by which the cement may cling firmly to the wire, it is best to twist two small wires together instead of using one large one. Curing the Posts. — In order for the cement to become thoroughly cured or "set" water must be supplied to aid in the action. For the first thirty days the posts should be kept wet if the best results are to be expected. The most favorable conditions for conserving the moisture consists in curing the posts in a shed where the wind does not strike them. Under these conditions neither the sun's rays nor the wind have a chance to dry out the posts too rapidly. The posts should be thoroughly sprinkled every day for at least thirty days. Wire Fasteners. — An inventor has devised a cast-iron socket which is placed in the post. Later the wire is fastened to the post by driving a staple into the socket or staple holder. The staples pull out easily and the sockets add greatly to the cost of the post. Another system consists of two staples which have the prongs bent to the side. The staples are placed about one-quarter inch apart, with the prongs projecting to the side. The line wire is placed between the two staples and a nail or a piece of wire is driven down through the staples, outside of the line wire. As the tips of the staple touch the reinforcement wires, direct electric con- nections are established between the line wire and the ground at the bottom of the post. This, it is claimed by the patentee, insures the user against loss of stock by lightning. The system is called the "Double Staple." (See Fig. 2.) Cement and Concrete Fence Posts. 9 A "single staple" may also be used, but the wire is fastened to the staple by a small "cold shut link," or wire ring. The latter system is not a very strong method of fastening, owing to the ease with which the cold shut links open. (See Fig. 2.) Perhaps the most common method of fastening wires to cement or concrete posts consists of tying in the line wire to the post by means of a piece of smaller wire called a "tie wire" (usually No. 14 or No. 15 wire). The single tie consists of wrapping one end of the tie wire three 'or four times around the line wire, then passing the long end through a hole in the post and bringing it around to the face of the post where it is also wrapped around the line wire. (See Fig. 2.) Ifej^ IWWl lUjcW^ CROSSS€Cr/ONSB£L OW. /HOL£ A wcf/ yftOL£ - S/A/Cl£ r/r. DOUBL £ r/€. A T/£AR0UMOP0ST. fACF V/£W. rAC£ V/£W. CROS'S S£CT/ONS. i^ FAC£ Vt£W. S^CT/ON TMROi/CUcO. sTcnoAfor HOLDER STAPL£ /A/ flLAC£. DOUBl£ STAftX. S/AfCL£ S'TAPL£ CAST /ROA/ AAfD fUMC. STAPL£-HOLD£R. B Figure II. Different Types of Wire Fasteners. — A. Home made fasteners. B. Commercial fasteners. The tie around post is much the same as the single tie, except that the tie wire passes around the post instead of through the hole. (See Fig. 2.) Neither the single tie or the tie around post are very strong unless the tips of the tie wire are hooked over the lo The C01.0RAD0 Experiment Station body of the tie wire after the wraps have been made. This is known as the "special tie." The strongest and perhaps the most satisfactory system of tying in the wire is the ''double tie." The tie wire is bent into the form of a long staple, straddled over the line wire and both ends passed through a hole in the post. One end is brought to either side and wrapped about the line wire at the face of the post. This system insures a solid fastening and is equal in strength to any ordinary wood post fastening. The holes in the posts are formed by No. 6 wires being placed in the post while it is soft. These wires are called "Tie Hole Pins." (See Fig. i.) They are removed from the poured post after the cement has set for 24 hours. The pins are removed from the tamped posts immediately before the molds are removed. The following table shows the comparative holding strength of various wire fasteners, as determined by the tests : WIRE FASTENERS (See description of same) KIND OF POST No. I.bs. Required to Pull Fastener REMARKS Ordinary 1% inch staple New Cedar 425 Average of 3 pulls. Staple was well driven into post. Single special tie Cement 520 Average of 2 pulls. Fence wire broke. Double tie Cement 510 Average of 2 pulls. Fence wire broke. Double staple Cement 245 Average of 3 pulls. Staples pulled. No. 14 wire plain single tie Cement 115 Average of 2 pulls. The wire untwisted. No. 14 wire around post Cement no Average of 3 pulls. The wire untwisted. Cast staple holder with ordinary 1% inch staple driven into it Cement 85 Ave. of 2 pulls. Staple pulled out of holder. Cold shut-link in single staple Cement 83 Ivink opened in every case. Ave. of 3 pulls. Taper of Posts. — To obtain the maximum strength with the least amount of material, the cement post must be so shaped as to have its greatest strength at the ground line. By making the post of uniform size from the base to the ground line, no material is wasted. The post may then be tapered from the ground line to the top. It has been found that in a 5-inch post which projects 4 feet above the ground, a taper of one inch on each side from the ground line to the top, insures almost equal strength throughout. This design gives more strength with less material than those with the continuous taper. Cement and Concrete Fence Posts. ii PART II. THE EXPERIMENTS These experiments were conducted for the purpose of deter- mining the method of building the best posts at the least cost. Apparatus. — Various commercial molds of different shapes and construction were secured. In each of these molds sev- eral posts were made in order to determine the practicability of the mold ; also the best combination of mixtures and reinforcements. The Farm Mechanics Department designed, built and used a simple home made mold which makes a post of uniform size from the base to the ground line with a rapid taper from the ground line to the top. (See Fig. i.) A shed which was closed on all sides with a sliding door on the east was used as the work and curing room. Materials — The sand and gravel used was clean and sharp, with all sizes of grains varying from small to large. There was a very small percentage of mica in the sand, which was objec- tionable. One brand of Portland cement was used for making all posts. A total of 238 line posts and 8 comer posts were built and tested during the experiment, the records of which are found in the following tables : Cost of Materials. — In figuring cost of materials the following prices were used : Sand and gravel, $1.00 per cubic yard. Cement, 60 cents per sack. New reinforcement, 4 cents per pound. Old barbed wire, 2 cents per pound. The Test. — In making the test, the posts were placed under as near fence conditions as possible. All line posts were set and firmly tamped into the ground so that 4 feet and one inch pro- jected above the surface. By means of a wire, a dynamometer was attached to the post exactly 4 feet from the surface of the ground. A steadily increasing force was applied to the dynamometer by means of a block and tackle, until the first visible crack appeared in the post when a reading was made. The force was then in- creased until the post gave away completely when the final reading was made. In making the posts enough of the mixture was provided for the construction of three posts at once. The three were cured alike for 60 days and were tested at the same time. The tables show the average results of the test on the three posts as one. In the reinforcement the short wires mentioned are two feet long and are placed in the post so the top extends about 12 inches 12 The Colorado Experiment Station above the ground line and the bottom about 12 inches below. One of these extra wires is placed in the face side of the post and tlie other in the back, so that they help to bear the strains on the post. In case of four extra wires, one is placed in each corner of the post with the other reinforcement wires. TABLE NO. 1. — ^Poured and Tamped Posts.* Size, 5x5 inches from base to ground line, tapering to 3x3 inches at top. Length, 6 feet 6 inches. Cured weight, 115 to 120 pounds. Mixture, 1 part cement and 3 parts sand by measure. Cost for cement for posts, 16.2 cents; sand, 3.7 cents. For cost of reinforcement, see table. COST FINAI, BREAK REINFORCEMENT Poured Posts Tamped Posts Kind of Wire Weight per post Cost per post Cost of Material in each Post Pounds to break Remarks Pounds to break Remarks No. 10, 4 twisted strands of 2 wires 2H 10.0c 29.9c 307 Wires broke 240 Mixture broke, wires did not break No. 10, 8 strands crimped 2!/2 10.0c 29.9c 254 Wires slipped and finally broke 263 Wires slipped, did not break No. 6, 4 long- wires hooked at ends 2% 10.6c 30.5c 232 All wires slipped 184 All wires slipped New barbed, 4 long strands 1% 6.6c 26.5c 188 Wires broke (Post was 130 days old) 123 Wires broke Old barbed, 4 long strands 1% 3.3c 23.2c 158 Wires broke 128 Wires broke New barbed, 4 long and 2 short 2 8.0c 27.9c 198 Wires broke Old barbed, 4 long and 2 short 2 4.0c 23.9c 200 Mixture broke above extra wires Old barbed, 4 long and 4 short 2% 5.5c 25.4c 229 IvOng wires broke above extra wires No. 10, twisted 4 long and 2 short 3 12.0c 31.9c 290 Extra wires did no good 160 Extra wires did no good * This table is a summary of Tables 1 and 2, Bulletin 148, Colo. Exp. Sta. Amount of Labor Required for Making Posts. — No definite statements can be made as to the amount of time required to make a cement or concrete fence post. The amount of time will vary with conditions, handiness of materials, methods of mixing, etc. According to data obtained in the experiment, two men mixing by hand, with everything reasonably handy, can make from three to five 5-inch poured line posts per hour. Figuring labor at $2.00 per day, ten hours for each man, the cost for making a post would amount to about 10 cents each. Three men with a small home made mixer and a two horse-power gasoline engine for driving it, Cement and Concrete Fence Posts. 13 would be able to make at least twice as many posts as two men w^orking by hand and the cost for making would be very much less. The Effect of Alkali on Cement and Concrete Posts. — It has been found that some soils contain an excessive amount of alkali, which has a tendency to destroy concrete work. While no experimental work has been done to test the effect of such soils upon cement or concrete posts, it has been conclusively proven that cement drain and sewer tiles which come in contact with water w^hich has percolated through these alkali soils are soon destroyed. While it might be possible that the action on cement or con- crete posts would be slower than in case of the tiles, it is probable that the post would eventually be destroyed. For further information in regard to the effect of alkali on cement construction see Bulletin No. 69, of the Montana Agricul- tural Experiment Station, and Bulletin No. 132, Agricultural Ex- periment Station of the Colorado Agricultural College. TABLE NO. 2. — Poured and Tamped Posts.* Size, 5x5 inches from base to ground line, tapering to 3x3 Inches at top. Length, 6 feet 6 inches. Cured weight, 115 to 120 pounds. Mixture, 1 part cement andCJ> parts sand, by measure. Cost for cement per post, iftrt" cents; sand, j^^ cents. For cost of reinforcement, see table. 4^ ^^ COST FINAI. BREAK REINFORCEMENT Poured Posts Tamped Posts ^ind of Wire Weight per Pjst Cost per post Cost of material in each post Pounds to break Remarks Pounds to break Remarks No. 10, 4 twisted strands of 2 wires I'A 10.0c 26.9c 222 Mixture broke, wires not well placed 192 Wires broke No. 6, 4 long wires hooked at ends 2H 10.6c 27.5c 222 Wires slipped 162 Wires slipped No. 10, twisted 4 long and 2 short 3 12.0c 28.9c 322 Mixtures and wires about equal Old barbed 4 long strands 1^3 3.3c 20.2c 95 Wires broke, poorly placed 137 Wires broke Old barbed, 4 long and 2 short 2 4.0c 20.9c 127 Poor wire. Wires broke 142 170 Wires broke New barbed, 4 long and 2 short 2 8.0c 24.9c 172 Wires well placed, cement broke Wires not well placed Old barbed, 4 long and 4 short 2% 5.5c 22.4c 196 Wires broke New barbed, 4 long strands iH 6.6c 23.5c 160 Wires broke Sta. * This table is a summary of Tables 3 and 4, Bulletin 148^ Colo. Exp. 14 The Colorado Experiment Station TABLE NO. 3. — Poured and Tamped Posts.* Size, 5x5 inches from base to ground line, tapering to 3x3 inches at top. Length, 6 feet 6 inches. Cured weight, 110 to 112 pounds. Mixture, 1 part cement and 5 parts sand, by measure. Cost for cement per post, 17 pounds, 10.2 cents; sand, 1 cubic foot, 3.7 cents. For cost of reinforce- ment, see table below. CEME^ rT COST FINAI, BREAK REINFOR Poured Posts Tamped Posts Kinds of Wire Weight per Post Cost per Post Cost of material in each post Pounds to break Remarks Pounds to break Remarks No. 10,4 twisted strands of 2 wires 2M 10.0c 23.9c 235 Mixture broke (poor) 97 Mixture not strong enough No. 10, twisted 4 long and 2 short 3 12.0c 25.9c 220 Extra wires did no good 98 Posts split Mixture weak Old barbed, 4 long strands iH 3.3c 17.2c 113 Wires broke 117 Wires broke Old barbed, 4 long and 2 short 2 4.0c 17.9c 137 Mixture and wires about equal 113 Mixture and wires about equal New barbed, 4 long strands 1^3 6.6c 20.5c 123 Mixture and wires about equal 108 Mixture and wires about equal New barbed, 4 long and 2 short 2 8.0c 21.9c 140 Wires broke 103 Wires poorly placed No. 14, 4 twist- ed strands of 3 wires each 12.^ 6.6c 20.5c 130 Wires broke No. 14, 4 long and 2 short, 3 twisted strands each 2 8.0c 21.9c 175 Wires and mixture about equal Sta. This table is a summary of Tables 5 and 7, Bulletin 148, Colo. Exp Cement and Concrete Fence Posts. 15 TABLE NO. 4. — Poured Posts.* Size, 4x4 inches at base, tapering to 3x3 inches at top. Length, •} feet 6 inches. Cured weight, 80 pounds. COST OF MATERIAL AND FINAI. BREAK REINFORCEMENT Mixture, 1 part ce- ment and 3 parts sand. Mixture, 1 part ce- ment and 4 pans sand. Kind of Wire Weight per post in lbs- Cost per Post Cost of Material in Post Pounds to break post Cost of Material in Post Pounds to break post No. 10, 4 twisted strands of 2 wires zy. 10.0c 23.3c 183 20.6c 168 Old barbed, 4 long strands IH 3.3c 16.6c 108 13.9c 65 New barbed. 4 long strands 1% 6.6c 19.9c 105 17.2c 88 No. 14, 4 strands of 3 twisted 1% 6.6c 19.9c 102 17.2c 62 No. 14, 4 long and 2 short strands of 3 twisted 2 8.0c 21.3c 185 ♦ This table is a summary of Tables 6 and 8, Bulletin 148, Colo. Exp. Sta. The Three Cornered Post. — The following conclusions are drawn after testing 23 triangular posts. Size, 7 inches on each side at the bottom, tapering to 5 inches on each side at the top. Mixture, i part cement and 3 parts sand, by measure. Cost of material varying from 14 cents to 19 cents each. The three cornered post which is advocated to some extent, does not have as many points in its favor as it may seem. In the first place an equal amount of reinforcement in each comer of the post cannot make a post of equal strength from two opposite direc- tions. If a force is brought to bear against one of the flat sides of the post towards the opposite corner, the material in the corner will crush long before the wires will break on the side from which the force is exerted. On the other hand, if a force is brought to bear against one comer of the post towards the opposite flat side, ihe single reinforcement in the corner will break before the uiixttire has begun to crush on the flat side. An extra reinforcement in the comer on which the force is exerted towards the opposite flat side will make it practically as strong as the flat side. But when the force is again applied to the flat side towards the single corner which is doubly reinforced, the mixture in the corner gives away too soon and it is no better than with but a single reinforcement. i6 The Colorado Experiment Station. TABLE NO. 5. — Poured Posts. Size, 5x5 inches from base to ground line, tapering to 3x4 inches at top. Length, 6 feet 6 inches. Cured weight, 115 to 120 pounds. Mixture, 1 part cement, 3 parts sand, and 3 parts gravel, by measure. Cost of cement per post, 14 pounds, 8.4 cents; sand and gravel, 1 cubic foot, 3.7 cents. For cost of reinforcement, see table below. REINFORCEMENT TEST COST REMARKS Kind of Wire Weight Per Post I.bs. Cost Per Post Final Break in Lbs. lyocation of Break Above or Below Ground lyine Cost of Materials in Post New Wire is Fig- ured at 4c per I,b. and Old Wire at 2c per Lb. 4 strands of 2 wires twisted No. 10-- 2Vi 10.0c 218 Ground line Ground line 4 in. below 22.1c Wires broke on 2 and mixture broke on one 4 long and 2 short twisted strands No. 10 3 12.0c 330 4 in. above 12 in. above 4 in. below 24.1c Wires broke 4 long strands old barbed wire l?/3 3.3c 110 Ground line Ground line Ground line 15.4c wires broke 4 long- and 2 short old barbed wire- 2 4.0c 118 20 in. above 24 in. above 15 in. above 16.1c Wires broke, not well placed 4 long strands new barbed l?S 6.6c 143 4 in. below Ground line Ground line 18.7c Wires broke 4 long and 2 short new barbed wire. 2 8.0c 123 Ground line 3 in. above 10 in. above 20.1c Wires broke 4 long strands of 3 twisted wires, No. 14 l?i 6.6c 123 Ground line 27 in. above Ground line 18.7c Wires broke 4 long. 2 short strands of 3 twisted No. 14 2 8 0c 143 Ground line 7 in. below 4 in. below 20.1c Mixture broke on two and wires broke on one. Cement and Concrete Fence Posts. 17 TABLE NO. 6. — Corner Posts. Size, 8x8 inches from base to ground line, tapering to 5x5 inches at top. Length, 8 feet. Cured weight, 360 pounds. Mixture, 1 part cement, 2 parts sand, and 3 parts of gravel, by measure. Cured 90 days. Cost for cement per post, 51 pounds, 30.6 cents; sand and gravel, 3 cubic feet, 11.1 cents. For cost of reinforcement, see table below. Test shows pull exerted in pounds as by each of two fences pulling at right angles. REINFORCEMENT TYPE TEST COST REMARKS Kind of Rein- forcement Weight Per Post I.bs. Cost Per Post Poured or tamped First Crack in Ivbs. Final Break in Lbs. Location of Break Cost of Mater- ial per Post All reinforcements figured at 4c pound excepting old barbed wire at 2c. 2-8 ft. and 2-5 ft pieces ^ in. rod on tension side 16 64c poured 7200 8500 at brace 11.057 Short wires extend- ed from below ground line to above brace line Same as above 16 64c tamped 5050 5600 at brace 1.057 Short wires extend- ed from below ground line to above brace line 14 strands old barbed wire on tension side. 8 16c tamped 6300 7300 at brace .577 Mixture broke Same as above 8 16c poured 5900 7400 at brace .577 Mixture broke 10 twisted strands No. 10. on tension si«le 8 32c tamped 5400 7300 4 in. below brace .737 Mixture broke Same as above 8 32c poured 6300 6650 4 in. above brace .737 Mixture broke Size, 7x7 inches at base, tapering to 5x5 inches at top. Length, 8 feet. Cured weight, 250 pounds. Mixture, 1 part cement, 2 parts sand, and 3 parts gravel, by measure. Cured 90 days. Cost of cement per post, 36 pounds, 21.6 cents; sand and gravel, 2 cubic feet, 7.4 cents. For cost of reinforcement, see table below. REIN FORCEMENT TYPE TEST COST REMARKS Kind of Rein- forcement Weight Per Post Lbs. Cost Per Post Poured or tamped First Crack in Lbs. Final Break in Lbs. Location of Break Cost of Mater- ial Per Post All reinforcements figured at 4c pound excepting old barbed wire at 2c 8 strands old barbed wire 2 in each comer 43^ 9c 2c lb. poured 2700 3600 at braces $0.38 Mixture broke 8 strands new barbed wire 2 in each comer AH 18c 4c lb. poured 3225 4050 at braces .47 Mixture broke HOIvLOW POSTS. It has been suggested that the cement and concrete posts should be made hollow. The hollow post would require less mixture and it would also be lighter. As the material in the center of the post does not have a good opportunity to act to the best advantage in cr mpression, it is argued that the strength of the hollow post would be nearly as great as that of the solid post. i8 The CoIvOrado Experiment Station. In case time is of little value it would probably prove more economical to build hollow posts. As the amount of reinforcement is not affected by the change from the solid to the hollow post, only the saving in cement, sand and gravel need be considered. It is an easy matter to compute the saving accomplished by the making of hollow posts, and then by knowing the cost of labor, the economy of building them may soon be calculated. With cement at 55 cents per sack and sand at $1.00 per yard, one cubic foot of i to 4 mixture costs 18 cents. If a i^ inch hole were to be left in the center of a post 7 feet long about ij^ cents' worth of material would be saved. With labor at 15 cents per hour, 6 minutes might be given to the extra work of making- the post with the hollow core. In case of alkali soils the hollow center gives additional ex-^ posed surface upon which the alkali may act. In a 4-inch square post with a 1% inch core, the extra surface amounts to about 28 per cent, of the original lateral surface. Finally there is a serious question as to the relative strength and durability of the hollow post as compared with the solid one. CORNER POSTS AND GATE POSTS. In the building of a fence with cement or concrete posts, the corner and gate posts must be especially strong, so as to prevent the pull of the wires coming upon the line posts. All the pull of the wires should be borne by the corner or gate posts. With this in mind the designer should aim not only to build a very strong post, but the system of bracing should receive special attention. As the cement posts are not as strong as wood posts, we can- not use the same bracing systems, which are so commonly in use in wood post fence construction. It has been found advisable to place the brace so that it supports the post at a point very little, if any, above the middle of the post. For the reason that the posts are strong in compression, but do not stand as much pull as wood posts, it proves advisable to place the brace against the brace post at least one foot below the ground line; thus the post distributes the pressure at the end of the brace against an area of ground equal to the surface covered on the opposite side of the post. There should be several wires connecting the brace post and the corner or gate post together. These wires should be placed under the ground at a depth of about one foot. By having these wires tight the corner post cannot move unless the brace post moves, and as this is securely fastened to it, the whole becomes a unit, offering a rigid resistance to the pull of the fence. In case of a corner post, the wires may be fastened by wrap- ping them around it, but the most satisfactory way is to cast wire staples in the post. These staples should extend into the post far Cement and Concrete Fence Posts. 19 enough to be wrapped around one or more of the reinforcement wires. The hinges for gates may also be cast in the posts when it is desired to do so. Corner and gate posts are usually reinforced in the same way as line posts. It is unnecessary, however, to place reinforcement wires on the inner sides of the corner posts, as the outer sides bear almost all of the tension. With the tapered posts, it is desirable to construct the face sides straight; this brings all of the taper on the other two sides. Small lugs or shoulders should be cast on eacli brace side of the post, against which the brace is placed. The ordinary five-inch line post proves to be strong enough to act as a brace post for an eight-inch corner post. The following table gives a summary of breaking strength and cost of materials of some of the best poured posts, which were made and sted in this experiment. REINFORCEMENT MIX- DESCRIP- TURE, TION 41^ng No. 10 Twisted 4 long 2 short No. 10 twist- ed 4 long New Barbed Wire 4 long Old Barbed Wire 4 long 2 short new barbed 4 long 2 short old barbed 3 long No. 1958 in .band iron 4 loTig 4 short old barbed 6 long old barbed 1 to3 Ground line 5x5 top 3x3 307 lbs. 29.9c 290 lbs. 31.9c 188 lbs. 26.5c 158 lbs. 23.2c none none 200 lbs. 23.9c 1 to 4 Ground line 5x5 top 3x3 222 lbs. 26.9c 322 lbs. 28.9c none none 95 lbs. 20.2c 172 lbs. 24.9c 127 lbs. 20.9c Ground ^ 1 line 5x5 1 to 5 1 lop 3x3 235 lbs. 23.9c 220 lbs. 25.9c 123 lbs. 20.5c 113 lbs. 17.2c 140 lbs. 21.9c 137 lbs. 17.9c lto3 Base 4x4 top 3x3 183 lbs. 23.3c none none 105 lbs. 19.9c 108 lbs. 16.6c lto4 Base 4x4 top 3x3 168 lbs. 20.6c none none 88 lbs. 17.2c 65 lbs. 13.9c lto33 Ground line 5x5 top 3x3 218 lbs. 22.1c 230 lbs. 24.1c 143 lbs. 18.7c 110 lbs. 15.4c 123 lbs. 20.1c 118 lbs. 16.1c 1 to3 Base 5x5 top 3x3 horse shoe shape 202 lbs. 23.3c 133 lbs. 16.6c • 157 lbs. 22 3c 148 lbs. 18.8c ; Triangular Base 7x7 to 3 ! top 5x5 110 lbs. 18.0c 147 lbs. 15.9c 20 L^iNi OTATION. Strength of cement posts compared to new wood posts tested under like conditions. KIND OF POST ( SIZE OF POST BREAKING STRENGTH REMARKS (1) Best cement post tested 5x5 in. at ground line tapering to 3x3.in. at top 322 lbs. (2) Cement Same as above 307 lbs. (3) Cement 4x4 in. at base tapering to 3x3 in. at top 185 lbs. The post was 3.6x 3.6 in. at ground (4) Split cedar (new) 3.6x3.6 in. at ground line 613 lbs. Same size at ground as No. 3 above White pine ' new) 4x4 in. at ground line 2000 lbs. Red spruce (new) 4^x4K in. at ground line 2400 lbs. Red spruce fnew) 5x5 in. at ground line 3350 lbs. CONCLUSIONS. Poured posts are easier to make than tamped ones. They are some- what more expensive because one mold will make but one poured post per day, while the same mold may be used for making as many tamped posts as the builder can mix and tamp in the same time. According to the tests made poured posts are a little over 25 per cent stronger than tamped ones of the same size, mixture and reinforcement. Poured posts are not so porous as the tamped ones and are therefore more nearly water proof, thus making them better able to withstand tha action of frost and alkali. The poured post is enough better in every respect to justify its con- struction and use in preference to the tamped one. Most commercial molds make a post which tapers from the base to the top, but the most economical mold is one which casts a post as large at the ground line as at the base, tapering from the ground line to the top. Fbr a description of this form of mold, see Fig, 4. The best form of post is one which is equally strong from all direc- tions. The square, or round post, fulfills this requirement. The tri- angular post does not meet the requirements because it cannot be econ- omically constructed so as to be equally strong from all directions. To be economical, the amount of reinforcement should be in propor- tion to the size of the post and strength of the mixture. See tables. The material used for reinforcement should be strong, light and rough enough to permit the mixture to get a firm grip upon it. It should be very rigid, with little or no tendency to spring or stretch. The smooth reinforcement tends to slip even if hooked at the ends. Two or more wires twisted together make as satisfactory a reinforce- ment as can be obtained. Crimped wire tends to straighten and thereby breaks pieces out of the post at the point of greatest stress. The reinforcement should be placed in each corner of the post at a depth of from % to % of an inch from the surface. There are several commercial wire fasteners now found on the market, the most of which are either cumbersome or expensive. For a simple and satisfactory fastener, see cut of fasteners. (Fig. 5, A.) The posts should be cured in the shade for at least 60 days, the first SO days of which they should be sprinkled daily. Photomount Pamphlet Binder Gaylord Bros. Makers Syracuse, N. Y. PAT. J« 21, 1908 ^^HH ^^llP ^^^f^'[^ / -[^ y '- ■'■■■ 496123 UNIVERSITY OF CALIFORNIA LIBRARY