unit weight of concrete = 1440kg/cubic meter
therefore unit weight is equal to weight over volume
given the unit weight already;
1440kg/cu.m = W/V
given also the weight of cement which is 50kg
so. cross multiply and we get
v= W/unit weight = 50/1440
and the answer is = 0.0347222 cu.m.

Okay guys I m new here i wanna ask you that ,if i mix two
three larger stones (about 20cm dia)in concrete for column or
footings what actually happens, how the strength of concrete
is reduced? and why it is not allowed?