Mortar

Mortar is a workable paste used to bind building blocks such as stones, bricks, and concrete masonry units together, fill and seal the irregular gaps between them, and sometimes add decorative colors or patterns in masonry walls.

The mortar paste is prepared by adding required quantity of water to a mixture of binding material like cement or lime and fine aggregate like sand. The binding material is also commonly referred to as the matrix and the aggregate is called adulterant. Cement mortar becomes hard when it cures, resulting in a rigid aggregate structure; however the mortar is intended to be weaker than the building blocks and the sacrificial element in the masonry, because the mortar is easier and less expensive to repair than the building blocks. Mortars are typically made from a mixture of sand, a binder, and water. The most common binder since the early 20th century is Portland cement but the ancient binder lime mortar is still used in some new construction. Lime and gypsum in the form of plaster of Paris are used particularly in the repair and repainting of buildings and structures because it is important the repair materials are similar to the original materials: The type and ratio of the repair mortar is determined by a mortar analysis. There are several types of cement mortars and additives.

Properties of good mortar

It should be capable of developing good adhesion with building units such as stones and bricks.
It should be capable of developing the desired stress levels
It should resist moisture penetration.
It should be durable and at the same time economical.
It must be workable and does not affect the strength of the materials it comes in contact with.
They should have minimum setting time so as to achieve fast construction.

Classification of mortars

On the basis of bulk density