### Material estimation for M20 grade concrete./ Estimating cement, sand, & aggregates in 1 CUM. of 1:1.5:3 mix ratio (M20)concrete.

Let us consider 1 CUM. of  M20 grade concrete for the calculation purpose.

Here,

Cement:sand: aggregates = 1:1.5:3 (a:b:c)

Wet volume of concrete = 1 cum.

Now, dry volume of concrete

= [1.54 × 1 cum]

= 1.54 cum.

1. Volume of  cement required

=[{ a ÷ (a + b + c)} × dry volume of concrete.]

= [{1÷ ( 1 + 1.5 +3 )} × 1.54]

= [{ 1 ÷ 5.5 } × 1.54]

=[ 0.18182 × 1.54]

=  0.28 cum.

As you know, 1 bag of cement = 0.03472 cum.

So, the number of cement bags required

= [0.28 ÷ 0.03472]

= 8.06 bags

Weight of cement

= [8.06 × 50 kgs.]

(1 bag of cement = 50 kgs.)

= 403 kgs.

2. Volume of sand required

=[{ b ÷ (a + b + c)} × dry volume of concrete.]

= [{1.5 ÷ ( 1 + 1.5 +3 )} × 1.54]

= [{ 1.5 ÷ 5.5 } × 1.54]

= [0.27273 × 1.54]

=  0.42 cum.

3. Volume of aggregates required

=[{ c ÷ (a + b + c)} × dry volume of concrete.]

= [{3÷ ( 1 + 1.5 +3 )} × 1.54]

= [{ 3 ÷ 5.5 } × 1.54]

= [0.54545 × 1.54]

=  0.84 cum.

4. Volume of water required.

Let us consider the w/c ratio for M20 grade concrete as 0.45.

i.e. wt. of cement / wt. of water = 0.45

So, the wt. of water

= [0.45 × wt. of cement]

= [0.45 × 403 kgs]

= 181.35 kgs

= 181.35 liters

( 1kg= 1 liter)

Note: This w/c ratio holds good if you use plasticizers. Practically for good workability, the water we add for the concrete is 200 to 220 liters.

#### Alternate method:

1. Volume of cement ( from above) = 0.28 cum.

2. Volume of sand

= [volume of cement × b]

=   [0.28 cum × 1.5]

= 0.42 cum.

3.  Volume of aggregates

= [volume of cement × c]

=  [0.28 cum × 3]

= 0.84 cum.

#### Quantity of materials in cubic ft.:

As you know, 1cum. = 35.3147 cu ft.

So, multiplying the above-derived quantity of materials with 35.3147, we will get,

1. Volume of cement

= [0.28 × 35.3147 cu ft.]

= 9.888 cu ft.

2. Volume of sand

= [0.42 × 35.3147 cu.ft.]

= 14.832 cu ft.

3. Vol. of aggregates

= [0.84 × 35.3147cu.ft.]

= 29.664 cu ft.

Now, let us put these material quantities in a table format for easy reference.

 Materials in 1CUM of M20 grade concrete. Sl. No. Item Unit In CUM. In cu ft. 1. Cement bags 8.06 bags - 2. Sand - 0.42 CUM 14.83 3. Aggregates - 0.84 CUM 29.66 4. Water litres 182 litres -

Similarly, for the different grades of concrete, you have to replace a, b, and c respectively for the given mix ratio, to get the answer.