concrete pouring

Concrete Grades And Their Applications

Concrete is one of the most famous materials in construction industry, and is comprised of a mixture of several materials such as cement, fine and coarse aggregates, and water. In fact, the aggregates bond together by cement and water within the mixture. Concrete specifications rely on the type, quality, and quantity of these ingredients in the mixture.

Among all characteristics, concrete strength is mostly determined by its water-to-cement ratio, and for example, having two identical fresh batches of concretes with the same mixture, adding more water to it lowers its final strength.

Grade of Concrete

Concrete mixes are classified by their grade, which pertains the minimum strength they will have after 28 days of construction with standard quality control and measurements and the strength is the amount of pressure needed to crush a 15 cm x 15 cm x 15 cm cube, which is measured in MPa. As an example, the grade of a concrete with strength of 10 MPa is denoted by M10. Each of the standard grades correspond to a specific mix proportion either.

Regular Concrete Grades

According to IS 456:2000, concrete is graded into 15 types which is shown in the below table:

Concrete Grade Mix Ratio Compressive Strength (MPa) Compressive Strength (psi)
Normal Grade of Concrete
M51 : 5 : 105 MPa725 psi
M7.51 : 4 : 87.5 MPa1087 psi
M101 : 3 : 610 MPa1450 psi
M151 : 2 : 415 MPa2175 psi
M201 : 1.5 : 320 MPa2900 psi
Standard Grade of Concrete
M251 : 1 : 225 MPa3625 psi
M30Design Mix30 MPa4350 psi
M35Design Mix35 MPa5075 psi
M40Design Mix40 MPa5800 psi
M45Design Mix45 MPa6525 psi
High Strength Concrete Grades
M50Design Mix50 MPa7250 psi
M55Design Mix55 MPa7975 psi
M60Design Mix60 MPa8700 psi
M65Design Mix65 MPa9425 psi
M70Design Mix70 MPa10150 psi

Regularly used grades of concrete are M15, M20, and M25. For construction projects with plain cement concrete, generally M15 grade is used and for reinforced concrete construction minimum grade of M20 is used.

Types of Mix Ratios

Concrete mix ratios indicate the proportions of cement, sand, aggregates and water components within concrete. The mixes are selected according to the construction type, project requirements, and mix designs. There are three types of mix rations, which are nominal mixes, standard mixes, and design mixes, that are described below.