86 



SILOS OTHER THAN WOOD. 



places it entirely above any criticism in regard to freezing. The 

 patent forms being made of steel plate enable a very smooth job 

 to be sequred. In general it would seem that the expense of a 

 double wall is not justified except in col<J climates." 



The foundation, as in all other concrete structures, is very 

 important. Not only must it serve as an anchor to protect the 

 structure against wind pressure, but it must also be very strong 

 and firm or the great weight upon it will cause it to settle un- 

 evenly, in which event the walls are liable to crack and so admit 

 air; consequently, spoiled silage will be the result. Where there 

 is a good clay floor, a concrete floor in the silo is not necessary. 



"The concrete silo when built as a monolith is practically a 

 unit. Its walls and roof are bound together by a net-work of 

 steel, laid in the concrete so as to withstand pressure from the 

 inside," says Wisconsin Bulletin No. 214. "A silo built this way 

 usually has walls six Inches thick, which are reinforced in pro- 

 portion to their size and capacity. The greater the height of a 

 silo, the greater the pressure on the wall at the bottom." 



Any silo bonded by ce- 

 ment is subject to contrac- 

 tion and expansion due to 

 changes of moisture and 

 temperature and should, 

 therefore, be reinforced 

 both horizontally and ver- 

 tically. Perhaps the best 

 reinforcement is secured 

 by twisting No. 9 tele- 

 phone wire together and 

 forming a cable. This 

 offers a rougher surface 

 than the steel rods and 

 forms a, continuous band, 

 which is very effective. The reinforcement should be laid in the 

 wall about one or two inches from the outside surface. Vertical re- 

 inforcement should be used in silos 25 feet high or more and is also 

 convenient for binding the circular cables in place. Short three- 

 foot lengths of %-inch steel rods are most satisfactory for this 

 purpose as they can be hooked together as the silo rises and not 



i ."^-^ 



^><floi'i. 





Fig. 28. — Horizontal 

 around silo door. 



Reinforcing 



