₦airaland Forum

Firstly, you need to determine the volume of space to be filled with concrete (wet volume of concrete), by using the product of the length (L), breadth (B) and width of the space (W).
VOLUME = L x B x W
Also, a suitable mix ratio is selected; preferably 1:2:4 (M15).
Let assume the space to be a slab of 10m by 5m by 0.15m OR 33ft by 16.5ft by 0.5ft
VOLUME = 10m x 5m x 0.15 = 7.5 m3 (cubic meter of wet concrete)
Note; Volume of dry concrete = 1.54 x Volume of wet concrete.
In other words, multiply the volume to be filled with concrete by 1.54; this caters for shrinkage and bleeding of concrete
Volume of dry concrete = 1.54 x 7.5m3 = 11.55m3
Using a mix ratio of 1:2:4(M15)
Volume of cement = 1/7 x 11.55m3 = 1.643m3
Bags of cement required = (1.643)/(0.035) = 46.9m3 ≅ 47 bags of cement.
Volume of sand = 2/7 x 11.55m3 = 3.268m3
Tonne of sand = 3.268m3 x 1.7 = 5.55 ≅ 6 tonne
Volume of Granite/Gravel = 4/7 x 11.5m3 = 6.57m3
Tonne of Granite = 6.57 x 2.4 = 15.77 ≅ 16 tonne

Civil leads!!

its also important to add up extra 10%, as wastage can only be reduced and not prevented

Soo simplified, I love that, keep it up co-engineer

how did you get 1.7 and 2.4 you used for sand and aggregate sir

Sheego92:
how did you get 1.7 and 2.4 you used for sand and aggregate sir

Am about asking same question.

Sheego92:
how did you get 1.7 and 2.4 you used for sand and aggregate sir

Density of granite and sand,..it suppose to be 2.75 for granite and 1.6 for sand.

What he did was: D=m/v he tried to get the quantities of granite and sand in kilograms / tonnes. I.e. m = Dxv (calculated)

Thank you, really insightful.