GRADES OF CONCRETE
Grades of concrete is defined as “the minimum strength the concrete must posses After 28 days of construction or casting along with the proper quality control” Grade of concrete is denoted by prefixing M to desired strength in MPa
For example
For grade of concrete with 20 MPa strength,
it will be denoted by M20
Where M stands for mix
These grades of concrete is converted in to
various mix proportions
To obtain the optimum strength
For example
M20 concrete
Mix proportions will be
1:1.5:3
Where
1 stands for cement
1.5 stands for sand
3 stands for aggregate
Nominal grade of concrete
|
Mpa
|
Psi
|
|||
M5
|
1
|
5
|
10
|
5
|
725
|
M7.5
|
1
|
4
|
8
|
7.5
|
1087
|
M10
|
1
|
3
|
6
|
10
|
1450
|
M15
|
1
|
2
|
4
|
15
|
2175
|
M20
|
1
|
1.5
|
3
|
20
|
2900
|
Standard grade of concrete
|
Mpa
|
Psi
|
|||
M25
|
1
|
1
|
2
|
25
|
3625
|
M30
|
mix design
|
30
|
4350
|
||
M35
|
mix design
|
35
|
5075
|
||
M40
|
mix design
|
40
|
5800
|
||
M45
|
mix design
|
45
|
6525
|
||
High strength concrete
|
Mpa
|
Psi
|
|||
M50
|
mix design
|
50
|
7250
|
||
M55
|
mix design
|
55
|
7975
|
||
M60
|
mix design
|
60
|
8700
|
||
M65
|
mix design
|
65
|
9425
|
||
M70
|
mix design
|
70
|
10150
|
||
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