Fire Brick: Composition, Properties, Types, Uses of Fire Bricks

Fire Brick

Fire brick is also called refractory brick. It is a type of brick that is built from fire clay. Fire clay has a very high melting temperature level of more than 1500 degrees Celsius as a result of its high alumina material. These bricks are designed to have high-temperature resistance, low thermal conductivity. Fire bricks are mainly used in kilns, fireplaces, and various other similar places where there is direct facing to high-temperature conditions.

Composition of Fire Brick


Fire brick is composed of mostly silica 60% to 90% with a smaller percentage of 10% to 30% of alumina and other materials like calcium oxides, magnesium, iron, potassium, and titanium which should not be

more than 5%, making it very dense and good quality fire brick.


Fire brick are generally categorized into three types


  1. Acidic Fire Bricks
  2. Basic Fire Bricks
  3. Neutral Fire Bricks

1. Acidic Fire Bricks

Acidic fire bricks usually described as acid-resistant bricks are particularly used to endure weathering chemical materials or acidic attacks.

Usually, a standard fire brick is made from natural fire clay, however, when extra acid resistance is needed, a further quantity of silica is added to the fire clay, which raises its composition, up to 97%. Maximum 2% of lime may be added for binding purposes. Acid bricks are burnt at high temperatures for a very long time.

2. Basic Fire Bricks

They are good for corrosion resistance and chemical resistance. They consist of high amounts of magnesia. Lime can be used as a bonding component. These bricks are magnetite bricks, dolomite Bricks, bauxite Bricks, magnesia-carbon, magnesia-chrome bricks, and many others.

3. Neutral Fire Bricks

These are good for both acidic and basic lining purposes. They present great resistance to acidic fumes and also corrosive actions.
Neutral bricks are of different types, chromite bricks, carborundum, chrome magnesite bricks, spinal bricks, forsterite Bricks, and alumina bricks. High alumina bricks consist of large quantities of alumina while chromite bricks include chromium, iron oxide, silica, iron oxide, and bauxite in variable proportions.


Use of Fire Bricks

Because fire bricks are manufactured to resist such high temperatures, they are the best bricks for fireplaces, kilns, furnaces, and various other high-temperature applications. While normal brick, stone, and some other materials will break from exposure to high temperatures, fire brick has the strength to stand up to fiery conditions for many years.

Fire brick can find in various sizes, and since it can be stained during the production procedure, and also get the desired shade. Fire brick is an appealing and reliable option for fire pit and fireplace. When using fire brick, make sure that it is fire-resistant and durable. The use of fire brick also benefits from its natural energy efficiency, as the fire brick insulates heat so the fireplace and fire pit stay as warm as possible.


Properties of fire brick

  • The color of fire bricks is usually white, or yellowish-white.
  • The standard brick size varies from 9 X 4.5 X 2.25 inches to 9 X 4.5 X 3 inches and is also manufactured in various sizes.
  • A standard fire brick weighs about 3kg each.
  • The compressive strength of fire brick ranges from 13.9Mpa to 15Mpa or 200 to 220 kg/cm2.
  • The water absorption ratio is less as compared to an ordinary brick about 5% to 8%.