FOUNDATION AND ROOF TYPES. 



99 



steel rods, the ends 

 of which are turned 

 up two inches in small 

 recesses in each end 

 of the block. When 

 the blocks are laid 

 into the silo wall, 

 these turned ends 

 and recesses match 

 corresponding ones 

 in the adjoining 

 block, as shown in 

 Fig. 42. A %-inch 

 round steel link is 

 then slipped over the 

 two turned ends 

 which are afterwards 

 filled in with cement, 

 very powerful and to 



Fig. 42. — Showing one method of sec- 

 tional block reinforcement. ■ — Cour- 

 tesy Hurst Silo Co., Chicago. 



bent back and drawn tight and the recess 

 This method of construction is said to be 

 give excellent results. 



Another method similar to the above, known as the Harvey 

 system, uses reinforcing rods which are turned at right angles 

 one turned vertically hooking over the other turned laterally. 

 Upright rods are imbedded in each block and fit between blocks 

 of the course above. This permits the building of a double wall 

 if desired, the two walls being tied together with steel strips 

 running diagonally between the upright rods. 



Cement Stave Silo. 



The cement stave silo is built of concrete slabs or staves 30 

 inches long, about 10 inches wide and ,2% inches thick. They 

 have a curved interlocking edge and are built Into a wall, 

 forming a wall of thickness of the block and bound tog-ether 

 with hoops on the outside. With good quality blocks, properly 

 treated with a water-proof wash so as to be impervious, this 

 type of silo is a success. It is claimed for them that all danger 

 of cracking due to contraction and expansion is eliminated. 

 For this reason although the steel hoops are not protected they 

 need no adjustment when once set. 



