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.                  

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.
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• 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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