Strength of concrete at various ages
Following table shows the strength of concrete at different ages.
| Age | Strength % |
| 7days | 65% |
| 14days | 90% |
| 28days | 99% |
Compressive strength of different grades of concrete at 7 and 28 days
| Grade of Cement | Minimum compressive strength N/mm2 at 7 days | Specified characteristic compressive strength (N/mm2) at 28 days |
| 15 | 10 | 15 |
| 20 | 13.5 | 20 |
| 25 | 17 | 25 |
| 30 | 20 | 30 |
| 35 | 23.5 | 35 |
| 40 | 27 | 40 |
| 45 | 30 | 45 |