Classification of Bricks Based on Raw Materials

Based on raw materials bricks are of the following kinds:

1.   Burnt Clay Brick: It is obtained by pressing the clay in moulds and fried and dried in kilns. It is the most used brick. It requires plastering when used in construction works. 

2.   Fly ash clay Brick: It is manufactured when flying ash and clay are moulded at 1000 degrees Celsius. It contains a high volume of calcium oxide in fly ash. That is why usually described as self-cementing. It usually expands when coming into contact with moisture. It is less porous than clay bricks. It proved a smooth surface so it doesn’t need plastering.

3.   Concrete Brick: It is made of concrete. It is the least used brick. It has low compression strength and is of low quality. These bricks are used above and below the damp proof course. These bricks are used can be used for facades, fences and internal brickworks because of their sound reductions and heat resistance qualities. It is also called mortar brick. It can be of different colours if the pigment is added during manufacturing. It should not be used below ground. 

4.   Sand-lime Brick: Sand, fly ash and lime are mixed and moulded under pressure. During wet mixing, a chemical reaction takes place to bond the mixtures. Then they are placed in the moulds. The colour is greyish as it offers something of an aesthetic view. It offers a smoother finish and uniform appearance than clay bricks. As a result, it also doesn’t require plastering. It is used as a load-bearing member it is immensely strong. 

5.   Firebrick: It is also known as refractory bricks. It is manufactured from a specially designed earth. After burning, it can withstand very high temperatures without affecting its shape, size, and strength. It is used for the lining of chimneys and furnaces where the usual temperature is expected to be very high.

Classification of Bricks Based on Manufacturing Method

Based on the manufacturing method bricks are of the following kinds:

1.   Extruded Brick: It is created by forcing clay and water into a steel dye, with a very regular shape and size, then cutting the resulting column into shorter units with wires before firing. It is used in constructions with limited budgets. It has three or four holes constituting up to 25% volume of the brick.

2.   Molded Brick: It is shaped in moulds by hand rather than in a machine. Moulded bricks between 50-65mm are available instantly. Other sizes and shapes are available 6-8 weeks after the order.

3.   Dry pressed Brick: It is the traditional type of brick which are made by compressing clay into moulds. It has a deep frog on one bedding surface and a shallow frog on another.

Classification of Bricks Based on Building Process

Based on the building process Bricks are of the following kinds:

1.   Unburnt Bricks: These are half-burnt bricks. The colour is yellow. The strength is low. They are used as suki in lime terracing. They are used as soiling under RCC footing or basement. Such bricks should not be exposed to rainwater.

2.   Burnt Bricks: Burnt bricks are made by burning them in the kiln. First-class, Second Class, Third Class bricks are burnt bricks. 

3.   Over Burnt or Jhama Brick: It is often known as the vitrified brick as it is fired at high temperatures and for a longer period than conventional bricks. As a result, the shape is distorted. The absorption capacity is high. The strength is higher or equivalent to first class bricks. It is used as lime concrete for the foundation. It is also used as coarse aggregate in the concrete of slab and beam which will not come in contact with water.

Classification of Bricks Based on Quality

Based on quality, Bricks are of the following kinds:

1.   First Class Brick: The size is standard. The color of these bricks is uniform yellow or red. It is well burnt, regular texture, uniform shape. The absorption capacity is less than 10%, crushing strength is, 280kg/cm2 (mean) where it is 245 kg/cm2 (minimum). It doesn’t have efflorescence. It emits a metallic sound when struck by another similar brick or struck by a hammer. It is hard enough to resist any fingernail expression on the brick surface if one tries to do with a thumbnail. It is free from pebbles, gravels or organic matters. It is generally used-

o in a building of long durability, say 100 years

o for building exposes to a corrosive environment;

o for making coarse aggregates of concrete.

2.   Second Class Brick: The size is standard, color is uniform yellow or red. It is well burnt, slightly over burnt is acceptable. It has a regular shape; efflorescence is not appreciable. The absorption capacity is more than 10% but less than 15%. Crushing strength is 175kg/cm2(mean) where the minimum is 154 kg/cm2. It emits a metallic sound when struck by another similar brick or struck by a hammer. It is hard enough to resist any fingernail expression on the brick surface if one tries to do with a thumbnail. It is used for the construction of one-storied buildings, temporary shed when intended durability is not more than 15 years. 

3.   Third Class Brick: The shape and size are not regular. The color is soft and light red colored. It is under burnt, slightly over burnt is acceptable. It has extensive efflorescence. The texture is non-uniform. The absorption capacity is more than 15% but less than 20%. The crushing strength is 140kg/cm2(mean) where the minimum crushing strength is 105kg/cm2. It emits a dull or blunt sound when struck by another similar brick or struck by a hammer. It leaves fingernail expression when one tries to do with the thumbnail.

TYPES OF BRICKS: DETAILED CLASSIFICATION OF BRICK

Bricks are a regular size rectangular units. Bricks are made of clay. They are usually used for most of the building works. Bricks are most generally used as a substitute for stone when the stone is not available.         

Types of Bricks

Bricks can be of many types depending on –

     i. Quality

  ii. Building Process

 iii. Manufacturing Method

 iv. Raw Material

   v. Using Location 

 vi. Weather-resisting Capability

vii. Purpose of Using 

viii. Shape 

 ix. Region