Mortar types (ASTM C270)
The strongest ASTM C270 mortar (min 2,500 psi). Used where high compressive strength and ground contact matter — foundations, retaining walls and load-bearing masonry below grade. Low workability.
| Designation | Type M |
|---|---|
| Ratio (by volume) | 1 : 0.25 : 3 |
| Portland cement | 1 part |
| Hydrated lime | 0.25 parts |
| Sand | 3 parts |
| Typical compressive strength | 2,500 psi · 17.2 MPa |
| Typical use | Below-grade, foundations, retaining walls, driveways. |
The strongest ASTM C270 mortar (min 2,500 psi). Used where high compressive strength and ground contact matter — foundations, retaining walls and load-bearing masonry below grade. Low workability.
Mortar type matters more than most people expect: a mortar much stronger than the units it beds will transfer movement into the masonry and spall the faces. Pick the weakest mortar that meets the structural and exposure demand.
Need quantities? The volume calculators give the cubic yards, cubic metres and bag counts for the pour this mix goes into.
Applications
Same family