Mortar types (ASTM C270)
A very soft, high-lime mortar (about 75 psi) reserved for conservation of fragile historic masonry. Not in the standard C270 property table for new work.
| Designation | Type K |
|---|---|
| Ratio (by volume) | 1 : 3 : 10 |
| Portland cement | 1 part |
| Hydrated lime | 3 parts |
| Sand | 10 parts |
| Typical compressive strength | 75 psi · 0.5 MPa |
| Typical use | Historic restoration of very soft masonry. |
A very soft, high-lime mortar (about 75 psi) reserved for conservation of fragile historic masonry. Not in the standard C270 property table for new work.
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.
Same family