Brief about Grade Of Concrete

What is Grade of Concrete?

Grade of concrete denotes its strength required for construction. For example, M30 grade signifies that compressive strength required for construction is 30MPa. The first letter in grade “M” is the mix and 30 is the required strength in MPa.

Based on various lab tests, grade of concrete is presented in Mix Proportions. For example, for M30 grade, the mix proportion can be 1:1:2, where 1 is the ratio of cement, 1 is the ratio of sand and 2 is the ratio of coarse aggregate based on volume or weight of materials.

The strength is measured with concrete cube or cylinders by civil engineers at construction site. Cube or cylinders are made during casting of structural member and after hardening it is cured for 28 days. Then compressive strength test is conducted to find the strength.

Regular grades of concrete are M15, M20, M25 etc. For plain cement concrete works, generally M15 is used. For reinforced concrete construction minimum M20 grade of concrete are used.

Concrete Grade	Mix Ratio	Compressive Strength
		MPa (N/mm2)	psi
Normal Grade of Concrete
M5	1 : 5 : 10	5 MPa	725 psi
M7.5	1 : 4 : 8	7.5 MPa	1087 psi
M10	1 : 3 : 6	10 MPa	1450 psi
M15	1 : 2 : 4	15 MPa	2175 psi
M20	1 : 1.5 : 3	20 MPa	2900 psi
Standard Grade of Concrete
M25	1 : 1 : 2	25 MPa	3625 psi
M30	Design Mix	30 MPa	4350 psi
M35	Design Mix	35 MPa	5075 psi
M40	Design Mix	40 MPa	5800 psi
M45	Design Mix	45 MPa	6525 psi
High Strength Concrete Grades
M50	Design Mix	50 MPa	7250 psi
M55	Design Mix	55 MPa	7975 psi
M60	Design Mix	60 MPa	8700 psi
M65	Design Mix	65 MPa	9425 psi
M70	Design Mix	70 MPa	10150 psi

Applications:

1) M5 Concrete

 # M5 is very lean mix concrete.

 # It can be used in any nonstructural work.

 # M5 grade concrete is generally used in foundation as PCC. PCC is weak in tension loading while strong in compression loading. 

 # This grade is widely used non structural member because it has less compression strength.

2)M10 Concrete

# To provide a flat base for laying ground floor slab and filling the depressed floor slabs.

3)M20 Concrete

# Domestic floors and foundations (where the weight of structure will be lighter). 

# Also good for workshop bases, garages, driveways and internal floor slabs.

4)M25 Concrete

# Construction in all areas. Multi-purpose concrete mix, usually used for foundations.

5)M30 Concrete

# Pathways and roadways (this is the lowest grade concrete mix that can be used for this purpose). 

# More durable than the grades that have come before, and thus is much more weather-resistant and can take heavy road traffic.

6)M35 Concrete

# Commercial structures. This heavy concrete mix is usually used for creating external walls and slabs, as well as for structural piling.

7)M40 Concrete

# Commercial construction sites, creating foundations and beams for structural support and roads. # The most durable in this list, C40 can withstand chemical corrosion also, so is frequently used on farms where slurry could corrode structures, or in septic tanks.

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