Fire bricks or Refractory Bricks

Fire bricks is a block of refractory ceramic material used in furnaces, kilns and fireboxes.

They are primarily built to resist excessive temperatures, usually have to decrease thermal conductivity for higher power efficiency.

Fire bricks can preserve excessive heat without melting or fusion, which usually consists of silicon dioxide and aluminium oxide.

The process involved in the manufacturing of firebricks at high temperatures to attain the specified results.

Typically, dense firebricks are used with excessive mechanical, chemical, or thermal stresses such as friction, wooden, or ash inside a furnace manufactured from wood for high-temperature diffusion.


Properties of fire bricks:

They are yellow-white or white in colour.

They can range in size from 9 X 4.5 X 2.5 inches to 9 X 2.75 X 2.25 inches.

A typical fire brick weighs about 30 to 35 N.

The compressive strength of fire brick ranges from 200 to 220 kg / cm2.

The water absorption ratio is 5 to 10%.

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Types of fire bricks:

Fire brick are broadly classified into three types:

1. Acidic Fire Bricks:

Acidic fire brick often referred to as acid-resistant brick, are especially used to withstand weathering chemical substances or acidic actions.


Generally, a traditional brick made of natural fire clay is nearly as good as a brick, but when more acid resistance is required, a further amount of silica is added to the fire clay, which increases its composition, up to 97%.

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 contain high quantities of magnesia, lime can be used as a bonding material.

The various fire bricks are magnetite bricks, magnesia-carbon, magnesia-chrome bricks, and many others.

3. Neutral Fire Bricks:

These are good in both acidic and basic lining functions.

They present good resistance to acidic fumes as well as corrosive actions.

Neutral bricks are of two types, namely, alumina bricks and chromite bricks.

High alumina bricks include large amounts of alumina while chromite bricks include chromium, iron oxide, silica, iron ore and bauxite in variable proportions.

fire brick
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Advantages of fire clay bricks:

1. Fire clay brick is environmentally friendly,

2. Fire clay brick is fireproof and heats insulation.

3. Fire clay brick is very inexpensive and very durable,

4. Fire clay brick has a good moisture-proof function

Disadvantages of refractory bricks:

1. Clay brick is made of concrete and much heavier than other masonry materials.

2. The soundproofing effect of clay brick is poor.

3. The main raw material of clay brick is clay, and it will harm the environment.

Use of fire bricks:

  • Fire brick is used for the following purposes as follow:
  • They are used for lining the inner floor of kilns, furnaces, chimneys, and many others.
  • To construct fire-resistant structures in order to reduce structural damage to fire accidents.
  • For the inner lining of an oven made from wood.
  • Ovens as an insulating material for furnaces, due to their low thermal conductivity.

Also, read 1. Clay Bricks

Frequently Asked Questions:

What is fire brick used for?

Fire bricks are used in lining furnaces, kilns, fireboxes, and fireplaces.

Do I need fire bricks in my fireplace?

Yes, fire bricks protect the steel sides from excess temperature.

What is the difference between fire brick and regular brick?

Fire bricks are used in building cooking chambers in ovens made of wood, and for building fireplaces, whereas regular or masonry bricks are more porous.

Are bricks safe for a fire pit?

Kiln-bricks are safe to use in a pit built from above ground.


Fire bricks are primarily built to withstand the high temperatures but will typically have lower thermal conductivity for greater energy efficiency.


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