CONCKETE 



Quantities of Materials in One Cubic Foot of Concrete 



427 



Example. — Let us suppose that the work consists of a con- 

 crete silo requiring in all nine hundred and thirty-five cubic feet 

 of concrete, of which seven hundred and fifty cubic feet are to be 

 1:2:4 concrete, and one hundred and eighty-five cubic feet are to 

 be 1 : 214 : 5 concrete. Enough sand and cement are also needed 

 to paint the silo inside and outside, amounting in all to four 

 hundred square yards of surface, with a 1:1 mixture of 

 sand and cement. One cubic foot of 1 : 1 mortar paints about 

 fifteen square yards of surface, and requires 0.1856 barrel of 

 cement and 0.0263 cubic yard of sand. The problem thus works 

 out as follows : 



Thus the necessary quantities of materials are about fifty- 

 seven and one-half barrels of Portland cement, about sixteen 

 and one-quarter cubic yards of sand, and thirty-one cubic yards 

 of stone or gravel. It is a,lways wise to order two or three 



