The preparation of concrete aggregates

A cubic yard of reinforced concrete consists of 30 to 33 cwts. of aggregate, 4 1/2 to 5 cwt. of cement and 1 1/2 to 2 cwt. of steel; so that the aggregate weighs six to seven times as much as the cement, and 15 to 20 times as much as the steel; therefore although a suitable aggregate may be bought at a fixed price delivered on the ground yet the labour of dealing with the aggregate may becom a very serious item. E. F. Sargeant