Properties of mortar

A good cement mortar should have the following properties:

1. Workability: it should be easy to mix, spread and use, and plastic enough to fill the joints completely.
2. Adhesion (bond strength): it should stick firmly to bricks and stones.
3. Strength: it must have enough compressive strength (for example 5-10 MPa for 1:4 mix, as required) to carry loads from the masonry.
4. Durability: it should resist weathering, frost and chemical attack.
5. Water retentivity: it should retain water long enough to prevent the masonry units from sucking it out.
6. Setting: it should set neither too fast nor too slow; it should not shrink or crack.
7. Impermeability: it should resist moisture penetration.
8. Economy and appearance: it should be cheap and give a good finish; it should be free from efflorescence-causing salts.
9. Mobility: it should flow under the trowel and fill all spaces.