How It Works: Concrete - Popular MechanicsOct 1, 2009 . An average 1:2:3 mix contains one part cement, two parts sand and three parts gravel. To make 1 cubic yard of concrete, you'd need seven.cement needed for 1 cubic of concrete of 1 2,Making Concrete - Clean WaterThat is 1 part cement, 2 parts sand, 3 parts gravel, and 0.5 part water. . For making concrete in a large volume, as will be needed for a pump pad, a cement trough . The volume of a square pump pad is calculated using the formula for a cube:.
cement needed for 1 cubic of concrete of 1 2