4 THE COLORADO 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 mixmg 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 



