# 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

#### 1. Nominal 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:-

1. Ordinary Grade Of Concrete ( Nominal Mix Concrete)

 S.No. Grade Designation Proportion of Concrete Mix Compressive Strength at 28 Days In (N/mm2) Quantity of water per 50Kg of cement in litres 1 M-5 1:5:10 5 60 2 M-7.5 1:4:8 7.5 45 3 M-10 1:3:6 10 34 4 M-15 1:2:4 15 32 5 M-20 1:1.5:3 20 30

2. Standard Grade Of Concrete (Designed Mix Concrete)

 S.No. Grade Designation Proportion of Concrete Mix Compressive Strength at 28 Days In (N/mm2) 1 M-25 Design Mix 25 2 M-30 Design Mix 30 3 M-35 Design Mix 35 4 M-40 Design Mix 40 5 M-45 Design Mix 45

3. High Strength Grade of Concrete

 S.No. Grade Designation Proportion of Concrete Mix Compressive Strength at 28 Days In (N/mm2) 1 M-50 Design Mix 50 2 M-50 Design Mix 55 3 M-60 Design Mix 60 4 M-65 Design Mix 65 5 M-70 Design Mix 70

Application of Different Grade 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.