During the construction works, you have to calculate materials required for preparing the concrete. In this article, we will discuss the calculation process to find the exact volume of materials required to prepare specific concrete of different grades.
The calculation depends upon the mix ratio of concrete materials.
Here is the table for concrete grade with the mix-ratio of materials.
Let calculate the quantity of materials for 1 m³ volume of concrete.
The mix of cement, sand, and aggregate is done according to the grades of concrete. Depending upon the nature of work and requirements, the selection of the different grades of concrete is done.
Let we take here M20 grade of concrete which means a mixture of cement, sand, and aggregate in the portion of 1: 2: 4
Before going to the calculation process, a few points you need to know,
- Dry volume of concrete material is 50-55% more.
- Density of cement = 1440 kg/cum
- The standard weight of 1 KG cement bag is 50Kg.
- Water cement ratio is taken 0.45.
- 1 m³ water = 1000 Litres
Let the wet volume of concrete = 1 m³
And, the dry volume of concrete (v) = 1 × 1.54 = 1.54 m³
Note: We need to take around 50-55% more materials (cement, sand, and aggregate ) in dry form so that after the mixture of materials with water the compacted volume will be less.
Here we take M20 grade of concrete so the mix ratio of cement, sand, and aggregate for M20 is 1:2:4 (a:b:c)
Calculation Process For Cement Concrete
Here we have total dry volume (V) = 1.54m³
Since, the mix ratio of concrete is 1:2:4, which means a mixture of 1 portion of cement, 2 portions of sand and 4 portion aggregates by volume.
So, the addition of total mix ratio= 1+2+4 = 7
Calculation to find quantity of Cement in concrete
Total volume of Cement = (Volume of dry concrete / total mix ratio) × portion of cement in concrete
= (1.54/7) x 1
= 0.22 m³
As mentioned above in the article, the density of cement = 1440 kg/m³ and weight of a bag of cement is 50kg.
∴ Weight of cement = density x volume = 0.22 x 1440 = 316.8 kg
∴ No. of total cement bags required = 316.8 / 50 = 6.33 bags.
Calculation to find quantity of Sand in concrete
For finding the volume of Aggregates used in concrete, we will use the following formulae.
The Volume of Sand = (Total dry volume of concrete/ total mix ratio) × portion of sand in concrete
= (1.54/7) x 2 = 0.44 m³
Calculation to find quantity of Aggregates in concrete
To find the quantity of Aggregates used in concrete, we will use the following formulae.
Volume of Aggregates = (Total dry volume of concrete/ total mix ratio) × portion of aggregates in concrete
= (1.54 / 7) x 4 = 0.88 m³
Calculation to find the volume of Water required
According to the IS code for concrete, the standard water/cement ratio is 0.45.
So, w/c = 0.45
∴Required water for 0.22 m³ cement = 0.22 x 0.45 = 0.099 m³
As we know, 1 m³ of water = 1000 Litres
∴ Required water in liter = 0.099 x 1000 = 99 liters.In this way we find out the quantity of materials required for the 1m³ concrete.
Reference Article: How to calculate the total cost for 1m³ cement concrete work?
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