Concrete Mix Ratio Design Types and their Strengths

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Generally concrete mixture ratios are the proportions of all the concrete components that include sand, cement, water and aggregates. All these substances mix ratios depends totally in the construction types and designs of mix. However, the building codes give the standard as well as nominal concrete mixture ratios for different construction works depending on the testing and experience. All these concrete mix type ratios are clearly explained below.

Types of Concrete Mix Ratio and their Strengths

Nominal Concrete Mix Ratios

Generally in past, the concrete specifications had recommended the proportions of cement, coarse and fine aggregates. These constant cement-aggregate ratio mix that gives the sufficient strength are marked as the nominal mixes. These nominal mixed provide simplicity and in normal circumstances, they do consists a strength more than specified. But due to difference in ingredients mix, these nominal concrete ratio for the workability given would widely vary in terms of strength.

Nominal mix ratios for these concrete mix are 1:2:4 for M15, 1:1.5:3 for M20 etc.

Standard Mixes or Ratio

The nominal mixes as mentioned above for cement aggregate ratio would result in wide variation of strength and also could lead to over or under-rich mixes. That why, the minimum compressive strength has got added in most of the specifications and it is called as standard mixes.

IS 456 2000 model has designated it’s concrete mixes as M40, M35, M30, M25, M20, M15, M10.

which are called as number of grades. In it the letter M indicates the mix and also the the twenty eight day cube strength mix in the units of N/mm2.

Designed Mix Ratio of Concrete

In this designed mixes, the concrete performance of given by the designer but the proportions or mix is specified by the concrete producer. However, the content of minimum cement could be excluded and can be paid down. This method is used mostly for the mix proportions sections that includes particular materials in mind consisting of less or more unique characteristics. This technique gives the concrete production with

appropriate properties most economically. However, these designed mixtures does can not be the guides as they doesn’t assure the exact mix proportions for the required performance.

Table given below gives the details of various types of concrete mix ratios and their strengths.

Concrete Grade, Mix Ratio, Compressive Strength, MPa (N/mm2)    psi

Standard Concrete Grade

M45    Design Mix    45 MPa    6525 psi

M40    Design Mix    40 MPa    5800 psi

M35    Design Mix    35 MPa    5075 psi

M30    Design Mix    30 MPa    4350 psi

M25    1 : 1 : 2    25 MPa    3625 psi

High Strength Concrete Grades

M70    Design Mix    70 MPa    10150 psi

M65    Design Mix    65 MPa    9425 psi

M60    Design Mix    60 MPa    8700 psi

M55    Design Mix    55 MPa    7975 psi

M50    Design Mix    50 MPa    7250 psi

Normal Concrete Grade

M20    1 : 1.5 : 3    20 MPa    2900 psi

M15    1 : 2 : 4    15 MPa    2175 psi

M10    1 : 3 : 6    10 MPa    1450 psi

M7.5    1 : 4 : 8    7.5 MPa    1087 psi

M5    1 : 5 : 10    5 MPa      725 psi

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