84 



SILOS OTHER THAN WOOD. 



"If it were possible to have the 

 work skillfully done a cement silo 16 

 feet in diameter and 35 feet high 

 could be built of reinforced concrete 

 with walls only 2 or 3 inches thick 

 and be abundantly strong. But labor 

 sufficiently skilled to do this would 

 cost too much, so that it would be 

 cheaper to use twice as. much cement; 

 make wall 6 or 8 inches thick and use 

 less skilled labor. If the work is 

 carefully done using ordinary labor 

 it is practical to build silos 16 feet 

 in diameter and 35 feet high with 6 

 or 8 inch walls if the steel rod is laid 

 in the wall every 2 or 3 feet." 



Reinforced concrete offers great 

 possibilities for silo building. The 

 lateral pressure on the walls when tha 

 silo is filled is very great, but the 

 circular shape renders it very easy 

 to reinforce. The single or solid wall 

 is most generally used. Good four- 

 inch wall silos have been built, but 



Fig. 27. Cement Silo 

 and No. 17 Ohio Cut- 

 ter at Experiment 

 Station, Sao Paulo, 

 Brazil. 



the six-inch wall offers greater convenience in placing reinforce- 

 ment and justifies the use of more material. The saving of ma- 

 terial by making the wall lighter at the top would hardly offset 

 the trouble of varying the size of the forms. 



The double wall or hollow wall concrete silos were designed 

 partly to overcome the freezing of the silage which has been the 

 one disadvantage of solid walls especially in cold climates. Ma- 

 chines are now on the market that easily and successfully build 

 reinforced and continuous hollow walls. Iowa Bulletin No. 141, 

 referring doubtless to conditions in that section, states that "the 

 double wall concrete silo at present is made only with patented 

 forms. The inner wall is 5% inches thick, the outer wall 3^ 

 inches thick, and the two tied together with steel ties with a 

 three-inch air space between. Circulation is prevented by insert- 

 ing horizontal tar paper partitions every 3% feet. This construc- 

 tion, besides being as satisfactory as the single wall method, 



