Concrete Silos 145 



this frame are embedded the vertical rods, to which 

 all the horizontal rods are hooked, in a manner simi- 

 lar to that described for monolithic silos. At other 

 times angle irons or U-bars are used for frames, or 

 special iron shapes, with offsets for doors are used. 



A wooden or metal chute can be fastened to the 

 walls or one can be built of blocks at the same time as 

 the walls. 



The roof of a block silo can be made either of wood 

 or of concrete. When of concrete, the method of pro- 

 cedure is the same as that specified for solid wall silos, 

 except that the temporary roof rafters rest on the 

 wall, and the eaves 'are formed 'by a special block 

 which gives the necessary overhang. 



Below are given brief descriptions of a number of 

 the systems of silo block construction now available. 



Hurst System. This system is marketed by the 

 Hurst Silo Equipment Company of Chicago. The 

 unit of construction is a solid block 231/2 inches long, 

 11% inches high, and 4 inches thick. Each block is 

 reinforced with two %-inch round rods, the ends of 

 these rods projecting into recesses at the end of each 

 block and being bent into a hook to receive a steel 

 link. When the blocks are laid up in the wall, the 

 ends of rods in adjoining blocks are thus brought to- 

 gether, and after the link is slipped over them the ends 

 are bent back by means of a tool supplied for the pur- 

 pose. This makes the reinforcing continuous around 

 the structure, and the process of bending up the rods 

 serves to bring the steel into tension and thus resist 

 the pressure of the silage when the silo is filled. The 

 recesses which hold the links are afterwards filled with 

 mortar, as well as the V-shaped joint between the 

 blocks on their inside surface. 



