CONCRETE CONSTRUCTION 247 



It is convenient to mix in batches requir- 

 ing even bags of cement. For example, a 

 two bag batch would mean two bags of ce- 

 ment, a quantity of sand equal to 4 bags 

 (3^4 cubic feet) and 8 bags (7/4 cubic feet) 

 of stone or gravel. They are mixed together 

 thoroughly, shoveling over several times be- 

 fore adding the water. 



Amount of Water. The quantity of water 

 used has but little effect on the resulting con- 

 crete, the amount depending rather on the 

 consistency at which the concrete can best 

 be handled for the special purpose for which 

 it is to be used. The dryer the mixture the 

 more quickly it will set. 



For thin walls, or where the form con- 

 tains many indentations, the mixture should 

 be thin enough to run off the shovel quickly 

 in handling. 



For walls of medium thickness (6 to 12 

 inches) or for floors, walks, etc., it should be 

 jelly-like in consistency, so that it will pile 

 up somewhat on the shovel, but will slowly 

 settle and run off the sides. 



For foundations, underground, where it is 

 important that the mixture set as quickly as 



