- Sand- The most common fine aggregate used in mortars is sand
- Cement- The component used to bind the aggregate
- Water- Potable water is used to hydrate the mixture
- Lime- may be added to increase workability, promote self-healing, and increase plasticity.
The most common type of mortar is the basic Portland Cement Mortar, a mixture of sand, portland cement, and water. It features a high compressive strength, it hardens at a consistent rate, it is effective in resisting damage during freeze/thaw cycles, and has a low water retention.
Lime mortar is a mixture of sand, slaked lime, and water, and is a breathable mortar (that is, it allows moisture to pass through it). It is used commonly in old buildings, and should be used when repointing them, as using a Portland Cement Mortar may trap moisture inside the wall system when it was originally designed to breathe.
Pozzolana mortar is a mixture of pozzolanic ash, lime, and water. It is a dense mortar and according it can be set underwater and can be stronger than Portland Cement Mortars.
There are five basic mortar types:
- Type M- high strength, used in reinforced masonry, usually below grade
- Type S- high strength, where lateral reinforcement is required
- Type N- medium strength, a general purpose type used above grade
- Type O- interior applications or non-loadbearing walls
- Type K- lowest strength, interior applications only