Question

Here is the list of materials for making concrete for 20 metres squared of floor. Concrete for covering 20 ml of floor Sand 50 kg Cement 25 kg Aggregate 100 kg The floor of a room is a rectangle with length 5 m and width 10 m. Work out how much of each of these materials is needed to cover this floor with concrete.

Answer 1

You didn't state the mix ratio of the concrete;

You omitted the thickness of the floor.

Assuming the mix ratio of the floor is 1:3:6 and the thickness of the floor is 150mm (1m by 1m by 0.15m).

The wet volume of concrete to cover the floor is therefore, 1 sq metre * 0.15 metre = 0.15 cubic metre.

The mix: 1:3:6 for cement: fine aggregate (sand): coarse aggregate (granite) by mass (kg).

1+3+6= 10

Ratio of cement required= 1/10

Ratio of sand required= 3/10

Ratio of granite required= 6/10

Dry volume of concrete = wet volume*1.52 =0.15*1.52= 0.228m^3

Volume of cement required= Dry volume*ratio of cement required = 0.228*1/10= 0.0228m^3

The Density of cement is 1440 kg/m^3

And 1 bag of cement is 50 kg

Therefore,

The mass of cement required= 0.0228 * 1440 = 32.832 kg.

The number of bags of cement required= 32.832/50 = 0.66 bag (ie 1 bag of cement is required to cover a 1m * 1m * 0.15m floor in a concrete mix 1:3:6).

NB: You can follow the same steps for other dimensions and mix ratios.