BRICKS AS BUILDING MATERIALS

BRICKS AS A BUILDING MATERIALS

MEANING 

Bricks are rectangular units of construction material conveniently handled with one hand. Brick may be made of burnt clay or mixture of sand and lime or of Portland cement concrete. Clay bricks are commonly used since these are economical and easily available.

Brick is obtained by moulding good clay into a block, which is dried and then burnt. This is the oldest building block to replace stone. Manufacture of brick started with hand moulding, sun drying and burning in clamps. A considerable amount of technological development has taken place with better knowledge about to properties of raw materials, better machineries and improved techniques of moulding drying and burning.

Bricks are used in masonry construction, walls, and pavements. It is used as a substitute of stone, where the stone is not readily available. Brick chips are often used as coarse aggregate in the concrete mix.

STANDARD SIZE OF BRICK

The length, width and height of a brick are interrelated as below:

•       Length of brick = 2 × width of brick + thickness of mortar       

•       Height of brick = width of brick

•       Size of a standard brick (also known as modular brick) should be 19 × 9 × 9 cm and 19 × 9 × 4 cm (190 mm × 90 mm × 90 mm and 190 mm × 90 mm × 40mm)

•       With mortar joints, the size of these bricks is taken as 20 × 10 × 10 cm (200 mm × 100 mm × 100 mm)

•       However, the bricks available in most part of the country still are 9" × 4.5 " × 3" and are known as field bricks. 

•       Weight of such a brick is 3.0 kg.

•       An indent called frog, 1–2 cm deep, as shown in Fig below, is provided for 9 cm high bricks. The size of frog should be 10 × 4 × 1 cm. The purpose of providing frog is to form a key for holding the mortar and therefore, the bricks are laid with frogs on top. 

CHARACTERISTICS/PROPERTIES OF BRICKS

The following are the required properties of good bricks:

1. Color

Color should be uniform and bright. The brick should have a uniform deep red or cherry color as indicative of uniformity in chemical composition and thoroughness in burning of the brick.

2. Shape

Bricks should have plane faces. They should have sharp and true right-angled corners.

3.Size

Bricks should be of standard sizes as prescribed by codes.

4.Texture

They should possess fine, dense and uniform texture. They should not possess fissures, cavities, loose grit and unburnt lime. The surfaces should not be too smooth to cause slipping of mortar. The brick should have pre-compact texture.

5.Soundness

When struck with hammer or with another brick, it should produce metallic sound.

6.Hardness

Finger scratching should not produce any impression on the brick.

7.Strength

Crushing strength of brick should not be less than 10N/mm².A field test for strength is that when dropped from a height of 0.9 m to 1.0 mm on a hard ground, the brick should not break into pieces.

8.Water Absorption

After immersing the brick in water for 24 hours, water absorption should not be more than 20 per cent by weight. For class-I works this limit is 15 per cent.

9.Efflorescence

Bricks should not show white patches when soaked in water for 24 hours and then allowed to dry in shade. White patches are due to the presence of sulphate of calcium, magnesium and potassium. They keep the masonry permanently in damp and wet condition

10.Thermal Conductivity

Bricks should have low thermal conductivity, so that buildings built with them are cool in summer and warm in winter.

11.Sound Insulation

Heavier bricks are poor insulators of sound while light weight and hollow bricks provide good sound insulation.

12.Fire Resistance

Fire resistance of bricks is usually good. In fact bricks are used to encase steel columns to protect them from fire.

                                By 

                                                  M.Darneshree

Assistant Professor, Dpt of IDD