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