Last edited 16 May 2018

Types of mortar

Mortar is one of the oldest building materials, enabling large structures to be constructed from small, easy-to-handle components. It was used by the Romans, Greeks and Egyptians, and the oldest example may date back as far as 10,000 years in Israel (ref. Mortar Industry Association).

It is composed from a mixture of a fine aggregate, a binder and water which creates a paste used in masonry construction as a bedding and adhesive to bind and fill the gaps between adjacent blocks of brick, concrete or stone. There are many different types of mortar that are used in building construction.

Mortars can be categorised based on the type of application they will be used for:

Mortar can also be categorised according to the type of binding material that is used, as this, along with quantities, will determine the quality and strength of the mortar:

Another way of categorising different types of mortar is based on their bulk density in a dry state. These include:

  • Heavy mortar: Bulk density of 15 kN/m3 or more. Typically, heavy quartzes are added as adulterants.
  • Lightweight mortar: Bulk density of less than 15 kN/m3. Typically, light porous and soft sands are added as adulterants.

There are also several special purpose mortars, including:

  • Fire resistant mortar: Aluminous cement is mixed with the fine powder of fire bricks to create a mortar which can be used to act as a fireproofing agent.
  • Sound absorbent mortar: Binders can be cement, lime, gypsum and slag, with pumice and cinders as adulterants, to create a sound-insulating layer.
  • X-ray shielding mortar: Heavy mortar with a bulk density of approximately 22 kN/m3 used to protect against X-rays.
  • Chemical resistant mortar: Additives can resist chemical attack.

Mortar is typically supplied in two different forms:

  • Wet ready-to-use mortar that requires no further mixing.
  • Dry ready-to-use mortar which requires the addition of water.

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