Concrete Grade M15: Strength, Mix Ratio, and Uses
M15 concrete reaches a characteristic cube strength of 15 newtons per square millimeter at 28 days. Here is what goes into it and where it belongs.
Characteristic strength: 15 N/mm² cube at 28 days
| Grade designation | M15 |
| Characteristic cube strength | 15 N/mm² |
| Approximate cylinder strength | 12 N/mm² |
| Mix | 1:2:4 nominal |
| Typical cement content | about 317 kg, 6.3 bags per cubic meter |
| Typical uses | plain concrete, footpaths, bedding, small unreinforced footings |
Notes for design and site
M15 is the classic volume batched mix for unreinforced work. Codes generally keep it out of structural reinforced concrete, but it remains the standby for surrounds, thrust blocks, and paths. Keep the water in check: an extra bucket per mix costs more strength than most people expect.
Related Calculators and Reference
- Concrete Mix Proportions and Yield: turn these ratios into bags and cubic meters.
- Construction Cost Risk Calculator: budget the pour with honest uncertainty.
- American Concrete Institute: authoritative concrete practice.