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:
- Bricklaying or stone-laying mortar: This type of mortar is used to bond together stones or bricks.
- Finishing mortar: This type of mortar is used for pointing and plastering works.
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:
- Cement mortar: The binder is cement and the fine aggregate is typically sand (ratio of 1:2 – 1:6). This provides good strength and water resistance.
- Aerated cement mortar: Air-entraining agents are added to cement mortar to increase its plasticity and workability.
- Lime mortar: The binder is lime, which is more ‘breathable’ than cement mortar, meaning that it is less likely to trap moisture within the construction.
- Lime putty mortar. Made by slaking quicklime with excess water without adding aggregate.
- Gypsum mortar: The binder is plaster. This type of mortar has low durability in damp conditions.
- Gauged mortar: A composite of lime, cement and sand, which combines the plasticity of lime with the strength of cement.
- Surkhi mortar: The binder is lime and the fine aggregate is surkhi (finely-powdered burnt clay). This provides more strength than sand.
- Hot-mixed lime mortar. Prepared by adding specific measures of quicklime to aggregate and water and mixing together to form a mortar that is hot.
- Dry hydrate lime mortar.
- Gauged mortar.
- Textile-reinforced 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.
[edit] Related articles on Designing Buildings
- Aggregate.
- Binding agent.
- Cement.
- Cement mortar.
- Dry hydrate lime mortar.
- Gauged mortar.
- Grout.
- Hot-mixed lime mortar.
- Hot-mixed mortars: the new lime revival.
- Lime mortar.
- Lime putty mortar.
- Mortar.
- Mortar analysis for specifiers.
- Plasticiser.
- Pointing.
- Portland cement.
- Rendering.
- Technical Paper 32 – A Data Driven Approach to Understanding Historic Mortars in Scotland.
- Textile-reinforced mortars TRM.
- Types of cement.
Featured articles and news
The UK's Modern Industrial Strategy: A 10 year plan
Previous consultation criticism, current key elements and general support with some persisting reservations.
Building Safety Regulator reforms
New roles, new staff and a new fast track service pave the way for a single construction regulator.
Architectural Technologist CPDs and Communications
CIAT CPD… and how you can do it!
Cooling centres and cool spaces
Managing extreme heat in cities by directing the public to places for heat stress relief and water sources.
Winter gardens: A brief history and warm variations
Extending the season with glass in different forms and terms.
Restoring Great Yarmouth's Winter Gardens
Transforming one of the least sustainable constructions imaginable.
Construction Skills Mission Board launch sector drive
Newly formed government and industry collaboration set strategy for recruiting an additional 100,000 construction workers a year.
New Architects Code comes into effect in September 2025
ARB Architects Code of Conduct and Practice available with ongoing consultation regarding guidance.
Welsh Skills Body (Medr) launches ambitious plan
The new skills body brings together funding and regulation of tertiary education and research for the devolved nation.
Paul Gandy FCIOB announced as next CIOB President
Former Tilbury Douglas CEO takes helm.
UK Infrastructure: A 10 Year Strategy. In brief with reactions
With the National Infrastructure and Service Transformation Authority (NISTA).
Ebenezer Howard: inventor of the garden city. Book review.
The Grenfell Tower fire, eight years on
A time to pause and reflect as Dubai tower block fire reported just before anniversary.
Airtightness Topic Guide BSRIA TG 27/2025
Explaining the basics of airtightness, what it is, why it's important, when it's required and how it's carried out.
Construction contract awards hit lowest point of 2025
Plummeting for second consecutive month, intensifying concerns for housing and infrastructure goals.
Understanding Mental Health in the Built Environment 2025
Examining the state of mental health in construction, shedding light on levels of stress, anxiety and depression.