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.

Concrete Mix Ratio For Various Grade Of Concrete

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.                  


2. Designed Concrete Mix 

In designed concrete mixes, the proportion of ingredients of concrete are determined to obtain concrete of specified properties with the overall economy.

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.

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