How to calculate cement sand and aggregate quantity in concrete

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Quantities of materials for concrete such as cement, sand, and aggregates for production of required quantity of concrete of given mix proportions such as 1:2:4 (M15), 1:1.5: 3 (M20), 1:1:2 (M25).

We assume that we have 30 cft volume of concrete and the mixing ratio is 1:2:4 (M15).
So we know that the unit weight of concrete is 150 lbs per cubic foot.  so, first of all, we need to find the weight of 30 cft concrete.

Weight of 30 cft concrete 

30 x 150 = 4500 lbs

We know that this is the weight of wet concrete so now we will find the dry weight of concrete.

for converting wet concrete weight to dry concrete weight the weight of wet concrete multiply with 1.54.

(If you want to know why we multiplied it with 1.54 then Read this : 

      Quantity Of Cement And Sand Calculation In Mortar CFT )

Dry weight of concrete 

4500 x 1.54 = 6930 lbs

Now we will calculate the quantity of cement, sand, coarse aggregate and water.

Calculation

First of all, we will find the sum of ratio

Sum of ratio = 1+2+4 = 7

Sum of ratio = 7

Now

Quantity of cement = 

( 1 ÷ 7 ) x 6930 = 990 lbs

We know that 1 Kg = 2.204 lb so

990 ÷ 2.204 = 449.18 kg  say 150 kg

We also know that  the weight of1 bag of cement is 50 Kg so

150 ÷ 50 = 3 bags

Quantity of cement = 3 Bags

Quantity of sand = 

( 2 ÷ 7 ) x 6930 = 1980 lbs

Quantity of sand in kg = 

1980 ÷ 2.204 = 898.36 kg say 900 kg

Quantity of sand = 900kg

Quantity of coarse aggregate = 

( 3 ÷ 7 ) x 6930 = 2970 lbs

Quantity of coarse aggregate in kg = 

2970 ÷ 2.204 = 1347.54 say 1348 kg

Quantity of coarse aggregate= 1348 kg

(Note = 0.4 to 0.6 water-cement ratio used in M15 concrete. we will take o.5 w/c ratio)

Quantity of water = 

0.5 x 150 = 75 liter 

(150 is the weight of cement)

Quantity of water = 75 liters 

Quantity of material in 30 cft:

Cement = 3 bags

Sand = 900 kg

Coarse aggregate = 1348 kg

Water = 75 liters

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