M20 grade of concrete is the most widely used concrete grade, that is mostly used in any construction. Most concrete structures construct with M20-grade concrete. So it is important to know M20 concrete mix ratio. Because the mix ratio of concrete determines the grade of concrete.
Concrete grades come in different grades like M5, M7.5, M10, M15, M20, M25, M30, M35, M40, and M45. Mainly there are two types of concrete.
- PCC
- RCC
Full form of PCC – PCC concrete means plain cement concrete. Steel bars are not used in plain cement concrete. It is only a mixture of cement, sand, aggregate, and water. PCC can not be used in any structural construction and has less strength than RCC.
Full form of RCC – RCC concrete means Reinforced cement concrete. It means when steel bars are used in any structure with concrete that is RCC structure. It is a also mixture of cement, sand, aggregate, and water but steel bars are used with all ingredients in it. RCC concrete is the most widely used concrete in any construction and it has more strength and durability than PCC concrete.
How many grades of concrete?
Concrete grades are categorized into 3 categories according to their mix ratios. (Here we are talking about cement, sand, and aggregate proportion in the concrete).
- Nominal mix-grade concrete
- Standard-grade of concrete
- Design mix-grade concrete
Nominal mix-grade concrete
M5, M7.5, M10, M15, and M20 are the nominal mix grades of concrete, In which M represent the mix and number represents the characteristic compressive strength of concrete after 28 days of curing. The nominal mix grade of concrete has measured by volume.
| Grade of concrete | Mix ratio | Compressive Strength after 28 days of curing |
|---|---|---|
| M5 | 1:5:10 | 5 N/mm2 |
| M7.5 | 1:4:8 | 7.5 N/mm2 |
| M10 | 1:3:6 | 10 N/mm2 |
| M15 | 1:2:4 | 15 N/mm2 |
| M20 | 1:1.5:3 | 20 N/mm2 |
Standard Grade Concrete
M25, M30, M35, M40, and M45 are the standard grade of concrete, In this M represent the Mix and the number represents the characteristic compressive strength of concrete after 28 days of curing concrete. The standard grade of concrete most used concrete in the construction of any building project.
| Concrete grade | Mix ratio | Compressive strength after 28 days of curing |
|---|---|---|
| M25 | 1:1:2 | 25 N/mm2 |
| M30 | Design mix | 30 N/mm2 |
| M35 | Design mix | 35 N/mm2 |
| M40 | Design mix | 40 N/mm2 |
| M45 | Design mix | 45 N/mm2 |
Design/ High strength mix grade concrete
M50, M55, M60, M65, and M70 are the standard grade of concrete, In this M represent the Mix and the number represents the characteristic compressive strength of concrete after 28 days of curing concrete. The design mix grade of concrete has measured by the weight.
| Concrete grades | Mix ratio | Compressive strength after 28 days of curing |
|---|---|---|
| M50 | Design mix | 50 N/mm2 |
| M55 | Design mix | 55 N/mm2 |
| M60 | Design mix | 60 N/mm2 |
| M65 | Design mix | 65 N/mm2 |
| M70 | Design mix | 70 N/mm2 |
M20-grade of concrete
M20 grade of concrete is a nominal mix ratio of concrete. It is the most widely used concrete grade in the construction of any building project. M20-grade of concrete is very suitable for structural members like footing, columns, beams, slabs, etc. M20 concrete is always used with steel bars.
In the M20 grade of concrete M represent the mix and 20 represents the characteristics of compressive strength of concrete after 28 days of curing concrete. 20 N/mm2 is the compressive strength of the M20 grade concrete.
M20 grade concrete mix ratio
M20 grade concrete mix ratio is 1:1.5:3. It is a mixture of cement, sand, and aggregate, In this mixture 1 part is cement, 1.5 part is sand, and 3 parts is aggregate. The nominal M20 grade concrete requires water to be 0.55% of the cement quantity.
How to calculate cement, sand, and aggregate quantity in 1m3 of M20 concrete
Every grade of concrete has a different mix ratio. So the Weight of 1 cubic meter of M10, M15, M20, and M25 Concrete weight is different.
To calculate cement, sand, and aggregate quantity in a cubic meter of M20-grade of concrete we have to know some important data like.
- Density of cement = 1440 kg/m3
- Mix ratio of M20 grade concrete = 1:1.5:3
- sum of total ratio = 1+1.5+3 = 5.5
- Parts of cement in mix = 1/5.5
- Parts of sand in mix =1.5/5.5
- Parts of aggregate in mix = 3/5.5
Now, we will calculate the cement quantity in 1 cubic meter of M20 concrete
How much cement required for 1 cubic meter of M20-grade concrete
Cement quantity for 1 cubic meter M20 concrete = part of cement in mix × cement density
= (1/5.5) × 1440
= 261.818 = 262 kg.
This is the wet volume of cement now we have to convert the wet volume into dry volume. and to convert wet volume to dry volume we have to multiply by 1.54 according to the thumb rule.
Dry volume of cement = wet volume of cement × 1.54
= 262 × 1.54
= 403.48 = 403 kg.
403 kg or 403/50 = 8.06 bags of cement required for 1 cubic meter of M20 concrete.
How much Sand required for 1 cubic meter of M20-grade concrete
According to the mix ratio, the sand part in M20 concrete is 1.5. And the cement is 1 part.
So 1 part cement weight = 403 kg
Total mix ratio = 5.5
Then, sand quantity in 1 cubic meter of M20 concrete = cement weight × sand part in concrete.
= 403 × 1.5 = 604 kg. (This is the dry quantity of sand).
How much gravel required for 1 cubic meter of M20-grade concrete
According to the mix ratio, the aggregate part in M20 concrete is 3. And the cement is 1 part.
So 1 part cement weight = 403 kg
Total mix ratio = 5.5
Then, gravel quantity in 1 cubic meter of M20 concrete = cement weight × sand part in concrete.
= 403 × 3 = 1209 kg. (This is the dry quantity of gravel means it is without water).
How much water required for 1 cubic meter of M20-grade concrete
Water requires about 55% of the cement quantity for 1 cubic meter of M20 grade concrete according to the thumb rule.
So, the water quantity for 1m3 of M20 concrete = (55/100) × cement quantity
= 0.55 × 403
= 221.65 = 222 Liters.
Therefore 222 liters of water is required for 1 cubic meter of M20-grade concrete.
Conclusion
In this article, we have discussed the M20 grade of concrete and the mix ratio of M20 concrete. We have also discussed cement, sand, and gravel quantity for 1 cubic meter of M20 concrete.