In this article, I am going to discuss how to calculate Cement, Sand, and Aggregate quantity in concrete. It is an easy task to calculate how much construction material is required for the construction of slabs or the quantity of Cement Bags, Aggregates and Sand required in slab construction.
Look at this example, Suppose we have to construct a slab with a length and width of 30ft each and with a 6-inch thickness, that is 0.5 ft. For plain cement concrete works, the grade of concrete used is M15. i.e. Characteristic Compressive Strenth of 15N/mm^2.
The ratio of Cement, Sand and Aggregates used for the M15 grade of concrete is 1:2:4. That is one part of cement is mixed with two parts of sand and four parts of Aggregates.
In order to calculate the material used in the slab we need to calculate first the total volume of a slab which is given above: Length: 30 ft. width: 30 ft. and thickness: 0.5 ft.
Total Volume of Slab (V) V= LxWxH = 30x30x0.5 = 450 cft.
So, finally, we will get a total volume of 450 cubic feet. It should be noted that this total volume is the wet volume of this slab. Now we need to convert this volume to Dry volume.
The formula to convert From WV (wet volume) to DV (Dry volume) is DV=WV x 1.54.
So, DV will be Equal to 1.54 x 450 = 693 cft.
How to calculate cement quantity in Concrete
To calculate the Volume of cement the formula used is :
Volume OF Cement = Ratio of cement x DV
while the ratio of cement is 1, the total ratio is 7 and the dry volume of the slab is 693 cubic ft.
Volume of cement 1/7 x 693 = 99 Cubic ft. (The number of cement bags is equal to the Volume of cement divided by the volume of 1 bag.) the volume of 1 bag of cement contents 1.25 cubic ft. another had 1 bag cement = 1.25 cft.
The number of bags is required 99/1.25 = 79.2 which is almost 80 bags.
How to calculate the volume of Sand
to calculate the volume of sand the formula used is:
The volume of sand = Ratio of sand x Dry Volume of slab
Ratio of sand = 2, Total ratio = 7 and Dry volume of slab = 693 cft.
The volume of sand = 2/7 x 693 = 198 cft.
The required volume of sand is 198 cubic feet.
How to calculate Aggregates
To calculate the volume of Aggregates the formula used is:
The volume of Aggregates = Ratio of Aggregates x Dry Volume of slab
Ratio of Aggregates = 4 , total ratio = 7 and Dry volume of slab = 693 cft.
The volume of Aggregates = 4/7 x 693 = 396 cft
The required volume of aggregates is 396 cubic feet to construct a slab of 30x30x0.5 cft.
Read also: How to calculate Square feet and Brass