1. Silica (sand) – 50% to 60% by weight
2. Alumina (clay) – 20% to 30% by weight
3. Lime – 2 to 5% by weight
4. Iron oxide – ≤ 7% by weight
5. Magnesia – less than 1% by weight

Burnt brick is the most common building material eventhough sun dried bricks are also used.

Bricks are hardened by drying. They can be sun dried, which will be a weaker brick. The more common technique is in a kiln, but this uses wood to burn which is not a great sustainability method.

The consitency of a brick is mainly determined by the soil that is used, which varies greatly through out the country. The main factor is the clay/ silt content.

Termite mounds, which are common in Zambia, are often used in the making of burnt brick. The reason being is that this soil has a high clay content due to the process of termites digging.

The addition of concrete to the mix, even in small amounts, can add greater strength and durability.

Bricks are probably one of the most sustainable material. For most communities the clay is right there. There is a concern about the wood used for burning in the kilns. The process would be more sustainable if an alternative fuel could be found.

A factory standard for making of kiln fired clay bricks.