# Concrete Mix Ratio For Various Grade Of Concrete

## Concrete Mix Ratio For Various Grade Of Concrete

Cement concrete may be defined as building material obtained by mixing cement, sand, aggregates and water in suitable proportion and then curing this plastic mixture to a hard mass. It can be easily moulded to durable structure members. The volume of aggregates in concrete varies from 60 to 78%.
Concrete mixes are classified by its grade having specified crushing strength at 28 days as measured in standard condition with 150mm x150mm x 150mm size cube, that means the grade of concrete corresponds to its characteristic compressive strength.
M-20 shows the crushing strength of that cube having size 150mm at 28 days is 20 N/mm2.

### Type of Concrete Mix

1. Nominal Concrete Mix
2. Designed Concrete Mix

#### The Nominal concrete mix may be used for concrete of grade M5, M10, M15 and M20. The proportion of its ingredients are given below:

 Grade of Concrete Maximum Quantity of Dry Coarse and Fine Aggregates by Mass per 50 kg of Cement (kg) Proportion of Fine Aggregates to Coarse Aggregates by Mass Maximum Quantity of water per 50 kg of Cement (Litres) M5     M7.5     M10     M15     M20 800         625                  480         350         250 Generally, 1:2 but subject to an upper limit of 1:1.5 and lower limit 1: 2.5 60          45          34          32          60

The proportion of fine to coarse aggregates should be adjusted from the upper limit to lower limit progressively, as the grading of fine aggregates become finer and the maximum size of coarse aggregate become larger. Graded coarse aggregate should be used.

### Concrete is graded according to its compressive strength given in the table below:-

 Grade of Concrete Mix Ratio (Cement: Sand: Aggregate) Compressive Strength At 28 Days 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

Application of Different Grades of Concrete:-

• M-5,M-7.5,M-10,M-15  :- PCC ( Plain cement concrete ) e.g. Levelling course, bedding for footing,etc.
• M-20, M-25, M-30, M-35  :- RCC ( Reinforced Cement Concrete ) e.g. Slab, Beams, Columns ,footing etc ( for mild exposure).
• M-40: RCC e.g. Pre-stressed concrete slabs, beams, column, footing etc.
• M-45, M-50:- RCC e.g. Runways, Concrete Roads( POQ ) Prestressed concrete girders, RCC columns, Prestressed beams etc.
• M-55  :- RCC e.g. Prestressed concrete girders and piers etc.

• M-60, M-65, M-80: -RCC work where high compressive strength is required such as high rise building, long Span bridges, ultra-thin white topping and spillways of dams, coastal construction etc.

Also, Read - Compressive strength of cement concrete.