What are Concrete Grades?
Concrete Grades are set depending on the composition and strength of the concrete. After preliminary construction and a period of around 28 days, the concrete attains its least strength.
The measuring unit for calculating concrete grade is MPa, where M signifies for mix and the MPa for the complete strength.
The mixes of concrete are provided in ascending numbers of 5, which starts with 10 and illustrate the compressive strength of the concrete after the completion of 28 days.
For example, C10 contains the strength of 10N, C15 contains the strength of 15N, C20 contains the strength of 20N, and so on.
The availability of various mixes (M) is in different mix proportions of the several cement elements, sand, and coarse aggregates.
For example, the corresponding proportion, M20 is found in is of 1:1:5:3.
Other instances are given in the table below:
| Concrete Grade Mix Ratio | (cement:sand:aggregates) | Compressive Strength | |
| Grades of Concrete | Mpa(N/mm2) | psi | |
| M5 | 1:5:10 | 5 | 725 |
| M7.5 | 1:4:8 | 7.5 | 1087 |
| M10 | 1:3:6 | 10 | 1450 |
| M15 | 1:2:4 | 15 | 2175 |
| M20 | 1:1.5:3 | 20 | 2900 |
Standard Grade of Concrete
| Grades of Concrete | (cement:sand:aggregates) | Mpa(N/mm2) | psi |
| M25 | 1:1:2 | 25 | 3625 |
| M30 | Design Mix | 30 | 4350 |
| M35 | Design Mix | 35 | 5075 |
| M40 | Design Mix | 40 | 5800 |
| M45 | Design Mix | 45 | 6525 |
High Strength Concrete Grades
| Grades of Concrete | (cement:sand:aggregates) | Mpa(N/mm2) | psi |
| M50 | Design Mix | 50 | 7250 |
| M55 | Design Mix | 55 | 7975 |
| M60 | Design Mix | 60 | 8700 |
| M65 | Design Mix | 65 | 9425 |
| M70 | Design Mix | 70 | 10150 |
Proper selection of the concrete grade is done according to the construction criteria.
Application of Concrete Grades:
Details of the preliminary concrete grades and their applications are provided below-
| Concrete Grade | Type | Applications/Uses |
| C10 | Domestic & commercial application | Used in patio slabs, pathways and non-structural work |
| C15 | Domestic & commercial application | Used effectively in pavement kerbs and floor blinding |
| C20 | Domestic application | Ideal for domestic floors and foundations (light weight bearing structure). Also perfect for workshop bases, garages, driveways and internal floor slabs. |
| C25 | Domestic & commercial application | Ideal for construction in all areas. For foundations, multi-purpose concrete mix is generally applied. |
| C30 | Commercial application | Used in pathways and roadways (belonging to the lowest grade concrete mix utilized for this purpose). Good longevity and strong resistance capacity against weather, ability to bear heavy road traffic. |
| C35 | Commercial application | Suitable for commercial structures. This heavy concrete mix is normally applied for development of exterior walls and slabs,as an addition to structural piling. |
| C40 | Commercial application | Effective for commercial construction sites as well as constructing foundations and beams for structural support and roads. It is the most long-lasting and can resist chemical corrosion. Its utility is on farms where slurry could rust structures, or in septic tanks. |