286 ILLINOIS STATE DAIRYMEN S ASSOCIATION. 



Cost of Concrete Silos. 

 The cost of a concrete silo will depend largely upon the cost 

 of gravel and labor, which varies greatly. The cost of gravel in 

 Iowa will range from nearly nothing where it is dug out of the 

 silo pit to a prohibitive price, owing to its inaccessibility. The 

 estimate of an average cost is assumed at $1.25 per yard. The 

 cost of labor varies much. On one silo of which a record of 

 the labor was kept, four men put 11 yards of concrete in an 8 

 inch wall in one day. In another well organized gang four 

 men put only 4 yards in a 6-inch wall. With labor at $1.75 per 

 day and a foreman $3.50, the labor in handling a yard of con- 

 crete ought not to cost much over $1.75. 



Cement Block Silos. 



This type of silo is very satisfactory if the blocks are well 

 made and plenty of steel has been provided in the wall for resist- 

 ing the bursting pressure of the silage. Where silos of this con- 

 struction have failed, this has not been the case. A convenient 

 block with a groove in the top in which the bands of reinforce- 

 ment are imbedded. The reinforcement should be entirely sur- 

 rounded by mortar in order to fully protect it from rust. 



The practice of using wooden studs embedded in mortar 

 at the ends of the blocks and at each side of the doorway and 

 bolted to the steel frame cannot be criticised too severely. This 

 stud is placed under conditions best adapted to cause rapid decay. 

 Often it is so constructed that it cannot be replaced without much 

 difficulty and thus the durability of the entire structure is im- 

 paired by the use of a single part. 



It is necessary to plaster the inside of the silo to make it 

 water and air tight. The block silo has the advantage over solid 

 wall concrete silos in that forms, outside of the block mold, are 

 dispensed with. The block is made hollow, thus providing 

 against freezing. The cost of the concrete block wall is usually 

 somewhat higher than the solid wall owing to the fact that as 

 large aggregate or gravel cannot be used and the cost of making 

 the blocks is about equal to the cost of making the solid wall with 

 the cost of laying the blocks in addition. 



