Classification of Bricks

CLASSIFICATION OF BRICKS

Bricks can be classified based on the following aspects:

❖ Based on their Quality 

❖ Based on constituent materials

❖ Based on usage

(i) Classification of Bricks based on their quality:

Bricks used for construction works are burnt bricks. They are classified into four categories based on their manufacturing process as given below.

First Class Bricks:

First class bricks are table moulded and are burnt in kilns. They are of standard shape and size with sharp edges. The colour should be uniform and bright. The bricks should give a clear metallic ringing sound when struck with each other. They fulfill all the qualities of good bricks and are used for superior work of permanent nature.

Second Class Bricks:

Second class bricks are ground moulded and they are burnt in kilns. The surface of these bricks is slightly rough and is somewhat irregular in shape. These bricks may also have hairline cracks and their edges may not be uniform and sharp. These bricks are generally used at the wall construction which are to be provided with a coat of plaster.

Third Class Bricks:

Third class bricks are ground moulded and they are burnt in clamps. These bricks have rough surfaces with irregular and distorted edges and are not hard enough. They cause dull sound when struck together. They are used for insignificant and temporary structures and also at places where rainfall is not heavy.

Fourth Class Bricks:

Fourth class bricks are over burnt bricks having dark colour with irregular shape. They are used as brick jelly for PCC works in foundations, floors, roads etc, since they have a compact structure

(ii) Classification of Bricks based on constituent materials:

There are various types of bricks used in masonry. They are classified into the following categories based on their constituent materials:

Common Burnt Clay Bricks

Common burnt clay bricks are formed by pressing in moulds, dried and burnt in a kiln. These bricks are used for general masonry work which requires plastering or rendering.

Sand Lime Bricks

Sand lime bricks are made by mixing sand, lime and fly ash pursued by a chemical process during wet mixing. The bricks are formed by moulding under pressure. The colour of the sand lime bricks are grey instead of the regular clay bricks which are in reddish colour. Their shape is uniform having smoother finish, hence plastering is not required.

Engineering Bricks

Engineering bricks are bricks manufactured at enormously high temperatures, resulting in a dense and strong brick. Engineering bricks offer outstanding load bearing capacity, damp-proof characteristics and chemical resisting properties.

Concrete Bricks

Concrete bricks are bricks made from solid concrete. These bricks can be manufactured in different colours by pigmented during its production. These bricks are usually used in facades, fences to provide beautiful aesthetic appearance.

Fly Ash Clay Bricks

Fly ash clay bricks are manufactured with clay and fly ash, at extremely high temperatures like 1000°C. When these bricks come into contact with moisture and water, they tend to expand.

(iii) Classification of Bricks based on usage:

Based on their utilization, bricks are classified into the following categories:

Building Bricks:

Building bricks are used for the construction of walls. Generally first class bricks are used for building works.

Building Bricks:

These are a porous form of brick formed by mixing small stone hardcore, dyes, cement and sand and other materials in various amounts. Brick Pavers are used in driveways, walkways, pool decks and other general outdoor surfaces.

Fire Bricks:

A fire brick or refractory brick is a block of ceramics used in lining furnaces, kilns, fireboxes, and fireplaces. These bricks are specially made to withstand furnace temperature. Silica bricks belong to this category.

Special Bricks:

Special bricks are different from the conventionally used bricks in their shape and utilization. Some of the special bricks are detailed below.

Specially Shaped Bricks:

 To meet the requirements of different situations, sometimes bricks are manufactured in special shapes. Some of these kind are bull nosed brick, coping brick, cant brick, channel brick, cornice brick, plinth brick etc,.

Perforated Building Bricks:

These bricks are manufactured with perforation which is uniformly distributed over the surface. The area of perforation should be 30 to 45% and each perforation should not exceed 500 mm2. The standard sizes are 190 × 190 x 90 mm and 290 x 90 x 90 mm

Facing Bricks:

Facing bricks are manufactured to be used for facing (façade) works at the exterior of the wall. These bricks are different from other structural brickwork and carry a very clean and even appearance. The standard sizes are 190 × 90 × 90 mm and 190 × 90 × 40 mm.

Burnt Clay Hollow Bricks:

These bricks are light in weight and are used for the construction of partition walls. The thickness of any shell should not be less than 11 mm and that of any web not less than 8 mm. They provide good thermal insulation to buildings. The standard sizes are 190 x 190 x 90 mm, 290 x 90 x 90 mm and 290 × 140 x 90 mm.

Acid Resistant Bricks:

Acid-resistant bricks are made of clay or shale, with low lime and iron content, and are vitrified at high temperatures in ceramic kilns. These bricks are used for floorings probable to be undergoing acid attacks, chamber lining in chemical plants, sewer lining carrying industrial wastes etc.

Sewer Bricks:

 Sewer bricks are made from shale or clay, burned to a greenish blue color in a flame of low oxygen in a kiln, and used in drainage structures for the conveyance of sewage, industrial wastes, and storm water. They standard sizes are 190 × 90 × 90 mm and 190 × 90 × 40 mm.