MONOLITHIC SILOS. 



85 



"If it were possible to have the 



Morlc slvillfully done a cement silo 16 



feet in diameter and 55 feet high 



could be built of reinfoVced concrete 



with walls only 2 or 5 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 S 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 55 feet high with 6 



or 8 inch walls if the steel rod is laid 



in the wall ever 2 or o feet." 



Reinforced concrete offers great 



possibilities for silo building. The 



lateral pressure on the walls when the 



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 



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 contmuous 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 514 feet. This construc- 

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



Fig. 27. — Cement Silo 

 and No. 17 Ohio Cut- 

 ter at Experiment 

 Station, Sao Paulo, 

 Brazil. 



