Refractory bricks or fire bricks are the type of bricks which can withstand high temperature as a construction material. The color of fire bricks is usually white, or yellowish white, and they weigh about 3 kg each. They must have a high fusion point.
Fire clay is used for making this type of bricks. This clay can resist high temperature without undergoing any appreciable change in structural properties like melting or softening.
Properties of Good Refractory Bricks
To serve the desired purpose the refractory bricks must be good in quality. Followings are the properties of good refractory bricks.
- Refractory bricks must resist stress developed at high temperature in furnace walls and arches.
- They must preserve their rigidity at high temperature.
- Irreversible volume change should not occur at the furnace temperature. Because shrinkage leads to the opening of joints and results in a leaky furnace.
- They must resist the tendency to crack and split off fragments when exposed to a sudden change of temperature.
- They must not easily form fusible products with slags.
- They must not react with furnace gases.
- Refractory bricks should weigh about 150 lbs per cubic ft (cft).
- They should take a compressive strength of about 20000 to 30000 psi.
- They should not absorb more than 6% of water by wt when kept in water for 24 hours.