Bricks: Composition, Ingredients and Types

What are the Bricks?

Bricks are hard structures and shapes in the form of block-type structures. And it can be used to construct buildings, pavements and other masonry structures. Bricks can be of many types, like clay bricks, cement bricks, etc.

Properties of bricks differ based on the types of bricks based on their composition, structure and other parameters. Bricks can be used for different purposes. Brick structures are constructed with the help of mortar joints.

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Composition of Bricks

Brick material generally consists of alumina, silica, lime, iron oxides, manganese, etc. Based on these ingredients, the properties of bricks vary. Excess quantities of these materials may cause harmful effects on the bricks' material. Here are the components of the brick clay are given below.

Ingredients of bricks

Ingredients of bricks are the materials that are used for the construction of bricks. Bricks may also be called harmful ingredients like pebbles, organic matter, alkalies, iron pyrites, etc. Raw materials for bricks include clay, silica and other ingredients. Brick material may contain the following ingredients. These ingredients are given in terms of the percentage of their weight.

• Silica 50% to 60%.
• Alumina 20% to 30%.
• Lime 2 to 5%.
• Iron oxide ≤ 7%.
• Magnesia less than 1%.

Types of Bricks

Based on the ingredients used to construct bricks, they may be classified into different types. Bricks can be classified into different types based on many parameters like manufacturing process, ingredients used, and process for drying bricks. Here some types of bricks are described below.

Fly ash bricks: These bricks are improved quality bricks. Which is used for the construction of many brick structures. It has better properties than clay bricks and can be used as one a replacement for clay bricks.

Cement bricks are light in weight; hence, they can be used to construct lightweight structures. In terms of strength parameters, cement bricks are weaker than clay bricks.

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Properties of Bricks

The properties of brick govern by the ingredients used for manufacturing the brick, the process of the manufacturing, etc. The most important properties of brick are

• Durability
• Colour
• Texture
• Size variation
• Compressive strength
• Absorption

Test for bricks

Certain tests are performed on the brick's material to determine the different characteristics of the bricks. These tests are illustrated below:

Crushing strength:

The crushing strength of bricks depends on the ingredients used for manufacturing bricks and may also depend on the manufacturing process. It also depends on the different classes of bricks. The minimum crushing strength for the first class of bricks is 10 Mpa; for the second class of bricks, it will be 7.5 Mpa.

Absorption capacity:

The maximum amount of water the dry brick can absorb.

Hardness:

In the hardness test of bricks, a finger nail is scratched if an impression has not been made; it is treated as a hard brick.

Shape and size test:

Brick must be tested for its shape and size. A brick should be perfectly rectangular and should have sharp edges. 20 bricks are randomly selected for the test for the shape and size.

Brick Structure:

The brick structure should be compact, homogeneous, and free from any holes, lumps, etc.

Soundness:

Two bricks are considered and struck together for the soundness test. Bricks should be a clear ringing sound and not break.

Classification of Bricks

Bricks can be classified based on the ingredients used and the process of manufacturing bricks. Broadly it can be divided into burnt bricks and unburnt bricks.

Burnt bricks:

Burnt bricks are bricks that are burnt in clay after their moulding. Burnt bricks are classified as first class bricks, second class bricks and third-class bricks.

Unburnt bricks:

Unburnt bricks are dried under the sun after the moulding. These bricks are used only for the construction of temporary structures. These bricks have lesser strength than burnt bricks. In the case of regions exposed to heavy rains, these bricks are not used.

Quality of Good bricks

Brick should be manufactured properly such that it gains maximum strength. Here are some properties of good bricks are listed below.

• The brick should be properly burnt in the kilns.
• Bricks should be free from cracks and have sharp square edges.
• It should be in a uniform shape and have in standard size.
• The brick structure should be compact and free from large voids.
• It should be hard enough to make no impression if it is scratched with the finger nail.
• It should not brittle more such that it will not break into different parts when dropped on a flat surface.
• For every class of bricks crushing strength should be at least 5.5 Mpa.

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