Correct Ratios for Concrete Mixes
If using a builder's wheelbarrow, you can assume that two sacks of cement (50 kg x 2) = one wheelbarrow load of either sand or stone. Low strength concrete could be mixed in the ratio of 1:4:4 and would be 10-15 MPa at 28 days. Medium strength might be 1:3.5:3.5 = about 25 MPa. High strength 1:2:3 = no more than 40 MPa.