Harmful Ingredients In Brick Earth/ composition of bricks

Composition Of Bricks


Brick is one of the key materials used in the construction of structures. The quality of the bricks matters a lot. Good composition of materials leads to the durability and high strength of the brick. Brick is the composition of Silica, Alumina, Iron Oxide, Magnesia, Organic matter, etc. The composition of bricks should be:



Percentage in brick

Silica (SiO2)55%
Alumina (Al2O3)30%
Iron Oxide (Fe2O3)8%
Magnesia (MgO)5%
Organic Matter1%


Composition of Bricks


 i) Alumina

* It is the main principle constituent of every kind of bricks.

* It gives plasticity to the earth and makes the brick hard.

* It is not mixed sand shrinkage may occur.

* Good brick contains about 30% of alumina.


ii) Silica

* It exists in brick mixed with clay as sand.

* Silica imparts hardness to brick.

* Addition of silica also increases durability and resistance to heat.

* Good brick contains about 55% of silica.


iii) Lime

* When lime present in small quantities in freely divided states it reduces shrinkage of bricks, helps silica melt at lower temperature and binds the particles of the brick together resulting in greater strength of brick.

* Excess of lime causes the brick to melt and lose the shape.

* Good brick contains about 1% of lime.


iv) Iron Oxide

* This oxide act as soft that it is lower down the softening of the temperature of silica and other components during firing or burning.

* Iron Oxide imparts a red colour to the bricks.

* Good brick contains about 8% of Iron oxide.


v) Magnesia

*A small proportion of magnesium decreases shrinkage and gives a yellow tint to the bricks.

*An excess amount of it causes bricks to decay.

* Good brick contains about 5% of magnesia.



Read Also: Harmful Ingredients in Brick Earth


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