Most modern building bricks are mainly made from clay and shale that are shaped and then fired at high temperatures to become hard and durable units. Other common bricks can be made from sand–lime mixes, concrete, or unfired earth (mudbricks), depending on the use and region.

Basics: What are bricks?

Bricks are small, usually rectangular blocks used in masonry walls, pavements, and other structures. Traditional bricks are designed to be strong in compression, weather‑resistant, and easy to stack with mortar into stable walls and arches.

Main materials in clay bricks

Most standard “red” clay bricks contain a mix of clay (alumina) and sand (silica), with smaller amounts of lime, iron oxide, and magnesia. Typical composition by weight is roughly 50–60% silica, 20–30% alumina, and smaller percentages of iron oxide, magnesia, lime, and traces of organic matter.

Other types of bricks

Not all bricks are fired clay; several other types are widely used. Common variants include:

  • Sand‑lime (calcium silicate) bricks made mostly from sand and lime, hardened under heat and pressure.
  • Concrete bricks made from cement, sand, and aggregates, often with pigments for color.
  • Fly ash bricks using fly ash, lime, and gypsum or cement, popular in some regions for sustainability and workability.

Unfired and traditional bricks

Mudbricks are unfired bricks made from a mix of clay, silt, sand, and sometimes straw or other fibers, dried in the sun instead of fired in a kiln. These earthen bricks have been used for thousands of years and can have a low environmental impact when properly protected from moisture.

Information gathered from public forums or data available on the internet and portrayed here.