Concrete Grade M40: Strength, Mix Ratio, and Uses
M40 concrete reaches a characteristic cube strength of 40 newtons per square millimeter at 28 days. Here is what goes into it and where it belongs.
Characteristic strength: 40 N/mm² cube at 28 days
| Grade designation | M40 |
| Characteristic cube strength | 40 N/mm² |
| Approximate cylinder strength | 32 N/mm² |
| Mix | design mix only |
| Typical cement content | commonly 380 to 450 kg per cubic meter, by design |
| Typical uses | marine structures, piles, prestressed girders, severe exposure |
Notes for design and site
M40 is as much a durability specification as a strength one: low water cement ratios near 0.40 produce a dense matrix that resists seawater and sulfates. Placing it is less forgiving, since the mix is sticky and sets with more heat, so plan pours, joints, and curing before the truck arrives.
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.