Composition of Bricks in Building Construction

Brick is a common building block material that has a uniform shape and size. This is a relatively cheaper construction material. Bricks are manufactured from plastic earth called the brick clay or brick earth.

Composition of Good Brick

The basic composition of good brick is:

1. Alumina
2. Silica
3. Magnesia
4. Lime
5. Oxide of Iron

1. Alumina

Alumina is one of the principal constituents of the brick, which constitutes around 20 to 30 percent by weight of the clay. The hardness of the brick is provided by the alumina content. Excess amounts of alumina will result in the shrinking of the brick and also tend to warp the brick with drying and burning.

2. Silica 

Silica in brick constitutes 50 to 60% in amount. It is the element that provides shaping property to the brick. This element in a desirable amount help to prevent cracking and warping observed in bricks during the burning process.

3. Lime

The lime content constitutes 5% in brick. This element contributes to 5 to 6 % in brick. The lime content in a desirable amount helps to prevent shrinkage. This helps in the hardening of the cement water mix. This also helps in the fuming of sand during brick manufacturing.

4. Oxide of Iron

The oxide of iron constitutes around 5 to 6 percent. This is the factor that gives red color to the brick. This also helps in the fuming of sand during brick manufacturing.
Oxide of iron is excess gives, blue color to the brick. Lesser amount results in the yellow color of the brick.

5. Magnesia

This content gives a yellow color to the brick. It also helps to decrease shrinkage in bricks. Magnesia present in excess amount results in the decay of the bricks.