How to work out the quantities of M20 grade concrete materials for a RCC slab

In this construction video tutorial, Mr. Sami Ullah, the renowned civil engineer briefly explains the process for working out the M20 material for RCC slab.

Suppose, there is a RCC slab and it’s length is 5 meter and breadth is 3 meter. The depth of slab for M20 grade concrete is 15 cm = 0.15 meter.

Initially, it is required to determine the volume of the slab as follow :-

Volume of slab = Length x Breadth x Depth
Volume = 5 x 3 x 0.15 = 6.75 cu.m
But, this is wet volume and you have to convert to wet volume.
For conversion to dry volume = wet volume x 1.54

So, dry volume = 6.75 x 1.5 = 10.39 cu.m
M20 grade concrete materials will be calculated for 10.39 cu.m volume.
For M20 nominal mix, the proportion of cement, sand and aggregate is 1:1.5:3 (cement : sand : aggregate).
So, sum of proportion = 5.5

So, the quantity of cement for RCC slab in 10.39 cu.m will be calculated as follow :-

Quantity of cement = ratio of cement/total ratio x total volume = 1/5.5 x 10.39 = 1.88 cu.m
We know the density of cement in 1 cubic meter = 1440 kg
Therefore, the weight of cement = 1.88 x 1440 = 2720 kg

To calculate the required number of cement bags = 2720 kg / 50 (since, the weight of 1 bag cement = 50 kg)
= 54.40 bags = 55 bags (approx)
So, 555 bags of cement are required for the above RCC slab.

Now, calculation should be done in the following way to find out the quantities of sand and aggregates :-
Qty of sand = 1.5/5.5 x 10.39 = 2.83 cu.m (as ratio of sand = 1.5)
Qty of aggregate = 3/5.5 x 1039 = 5.66 cu.m (as ratio of aggregate = 3)

To get more detail information, go through the following video tutorial.

Video Source: www.youtube.com