20 



liko 



Strength of cement posts compared to new wood 

 conditions. 



STATION. 



posts tested under 



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 the 

 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. For 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 stretcn. 



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. 



