128 



CONCRETE OR CEMENT SILOS. 



rod (^-inch iron) is laid in this groove and embedded in 

 the masonry. 



The cement block walls can be built more cheaply than 

 can the monolithic walls, providing the building is not 

 more than a mile or two from the factory where the blocks 

 are made, and in some instances the manufacturers will 

 move out their forms, mixers and other utensils for mak- 

 ing cement blocks and make the blocks at the building site 

 and still build more cheaply than the monolith can be 

 built. It is possible to do this because the work can be 

 done with greater facility on the ground level than up in 

 the air on scaffolding. Cement blocks are turned out 

 rapidly in a factory where all the facilities are at hand. 



Cement blocks are usually made of finer materials 

 than are the solid monolithic walls. The blocks are made 

 of sand and cement; or if any gravel is used, it is very 

 fine gravel, whereas, in the continuous wall, monolithic 

 construction, coarser gravel or crushed stone is more 

 commonly used. This is one of the reasons why the 

 monolithic wall is stronger than the block wall. 



The continuous wall may be made with holes or spaces 

 the same as the holes H, H, in the block, Fig. 39. This is 



Fig. 40. Illustrates a tapering wood block used in making hollow con- 

 crete walls. Courtesy Wisconsin Experiment Station. 



