The standard deviation used to calculate the mean strength of concrete for grade M25 is 4.0 N/mm2 as per IS: 10262-2009.
Standard Deviation for Concrete Mix Design
When designing a concrete mix, the standard deviation plays a crucial role in determining the target mean strength. This value reflects the expected variability in concrete strength for a given grade. According to the Indian Standard IS: 10262-2009, specific standard deviation values are assumed based on the concrete grade.
Standard Deviation Values as per IS: 10262-2009
The following table summarizes the assumed standard deviation values for different concrete grades, as per IS: 10262-2009:
| Grade of Concrete | Assumed Standard Deviation (N/mm2) |
|---|---|
| M20 | 4.0 |
| M25 | 4.0 |
| M30 | 5.0 |
| M35 | 5.0 |
| M40 | 5.0 |
| M45 | 5.0 |
| M50 and above | 5.0 |
It is important to note that these values are assumed initially. During the execution of the project, the standard deviation should be established based on actual test results, and the mix design adjusted accordingly to achieve the required target mean strength.
