CHAPTER VIII 

 THE IOWA SYSTEM OF BUILDING BLOCK SILOS 



Construction of the Wall. The first course of blocks in 

 an Iowa silo should be a trial course, the blocks spaced J/g 

 to % of an inch apart, without mortar, in order to determine 

 the proper diameter of the silo and the length of the guide. 

 This will overcome the necessity of cutting blocks. Steel 

 should be placed upon the outer half of the mortar course, 

 in order that there shall be enough mortar inside to bear 

 against the wire and hold the blocks. In case of a double 

 wall the steel should, of course, be on the inner wall. 



Loose blocks may be placed temporarily upon the wall to 

 hold the steel in place at intervals of 6 or 8 feet, as occasion 

 requires. Steel reinforcement in the joints below and above 

 the doorways should be long enough to lap past each other 

 and be hooked, as shown in Fig. 19. 



The horizontal or bed joints should be thoroughly bedded 

 to cover the steel reinforcement. The vertical joints at the 

 block end should be made with care in order to insure per- 

 fectly air- and water-tight joints. In order to do this the 

 ends of both blocks should be mortared before pressing 

 together. The outside joints should, for the sake of appear- 

 ance, be struck neatly with the trowel as the work progresses, 

 and for warmth they should of course be air tight. On the 

 inside, however, this is scarcely sufficient, as there might still 

 be an occasional opening left between the ends of the blocks, 

 which would permit the air to enter. 



The Cement Wash. In order to close all such openings, 

 leave the mortar hanging on the inside or cut it roughly; then, 



