Let us consider 1 CUM of M25 grade concrete for the calculation purpose.
Here,
Cement:sand: aggregates = 1:1:2 (a:b:c)
M25 grade means ðŸ‘‰ 1:1:2 ratio.
Wet volume of M25 grade concrete = 1 CUM.
Now, the dry volume of concrete
= 1.54 × wet volume of concrete.
= [1.54 × 1 cum] = 1.54 cum.
1. Volume of cement required
= [{its ratio ÷ (total ratio)} × dry volume of concrete.]
=[{ a ÷ (a + b + c)} × dry volume of concrete.]
= [{1÷ ( 1 + 1 +2 )} × 1.54]
= [{ 1 ÷ 4 } × 1.54]
= [0.25 × 1.54]
= 0.385 cum.
As you know, 1 bag of cement = 0.03472 cum.
So, the number of cement bags required
= [0.385 cum. ÷ 0.03472 cum.]
= 11.089 bags
Weight of cement
= [11.089 bags × 50 kgs.]
(1 bag of cement = 50 kgs.)
= 554.44 kgs.
2. Volume of sand required
= [{its ratio ÷ (total ratio)} × dry volume of concrete.]
=[{ b ÷ (a + b + c)} × dry volume of concrete.]
= [{1÷ ( 1 + 1 +2 )} × 1.54]
= [{1 ÷ 4 } × 1.54]
= [0.25 × 1.54]
= 0.385 cum.
= 13.60 cu ft.
3. Volume of aggregates required
= [{its ratio ÷ (total ratio)} × dry volume of concrete.]
=[{ c ÷ (a + b + c)} × dry volume of concrete.]
= [{2÷ ( 1 + 1 +2 )} × 1.54]
= [{ 2 ÷ 4 } × 1.54]
= [0.5 × 1.54]
= 0.77cum.
= 27.19 cu ft.
4. Volume of water required.
Let us consider the w/c ratio for M25 grade concrete as 0.4.
i.e. wt. of cement / wt. of water = 0.4
So, the weight. of water
= 0.4 × wt. of cement
=0.4 × 554.44 kgs
= 221.776 kgs
= 222 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 250 to 270 liters.
Alternate method:
1. Volume of cement ( from above) = 0.385 cum.
2. Volume of sand
= [volume of cement × b]
= [0.385 cum × 1]
= 0.385 cum.
3. Volume of aggregates
= [volume of cement × c]
= [ 0.385cum × 2]
= 0.77 cum.
Now, let us put these material quantities in a table format for easy reference.
Materials in 1CUM of M25 grade concrete. |
||||
Sl. No. |
Item |
Unit |
In cum. |
In cu ft. |
1. |
Cement |
bags |
11.089 bags |
- |
2. |
Sand |
- |
0.385 |
13.60 |
3. |
Aggregates |
- |
0.77 |
27.19 |
4. |
Water |
litres |
222 |
- |
Next part ðŸ‘‡
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