15 Characteristics of Good Bricks

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Brick is the most common building material used. Hence, it is valuable to understand the qualities of a good brick. The following list presents the characteristics required for good brick:

1. Size
2. Shape
3. Color
4. Texture
5. Compactness
6. Compressive strength
7. Hardness
8. Soundness
9. Toughness
10. Water absorption
11. Expansion
12. Extent of burning during manufacturing
13. Thermal conductivity
14. Efflorescence
15. Good brick earth

Size

The size of the brick should be uniform and must be of standard size. As per IS 1077(1992) the standard size of brick is 190 mm x 90 mm x 90 mm (or) 190 mm x 90 mm x 40mm.  

Shape

The brick must be of rectangular shape. The sides of the brick should be parallel Also, the edges of brick must be sharp and straight.

Color

Good brick must possess uniform color which may be either deep red or cherry. The uniformity in color of bricks represents uniformity in chemical composition and homogeneous burning of brick.

Texture

The surface of the brick must not be too smooth. Excess smoothness of the bricks result in slipping of mortar.

Compactness

The fractured surface of brick should not show fissures, holes or lumps.

Compressive strength

The crushing strength of the brick must not be less than 3.5 N/mm². The compressive strength test of brick is determined using Compression Testing Machine.

Hardness

Scratch the brick with a finer nail. The quality of the brick is considered as good when no impression is to be left on its surface.  

Soundness

Strike two bricks against each other. If a metallic ringing sound is produced, then the bricks are of good quality. A good quality brick must be able withstand severe weather condition.

Toughness

The brick should not break into pieces when dropped flat on hard ground from a height of about 1 m or 1.2 m.  

Water absorption

Water absorption of brick must be limited to 20% or 1/5 of the weight of the brick, whichever is lesser. Determine the water absorption of brick by either 24 hours immersion cold water test or 5 hours boiling water test.

Expansion

When wetted with water, the bricks should undergo minimum change in volume.

Extent of burning during manufacturing

The bricks should neither be under burnt nor be over burnt.

Thermal conductivity

The thermal conductivity of the bricks must be low so that houses constructed using them are cool in summer and hot in winter.

Efflorescence

Soak the brick in water for 24 hours and dry it in shade. The absence of white patches on brick surface indicates that the quality of brick is good. The formation of white patches is due to the presence of excess soluble salts (like sulphates of sodium, magnesium, calcium, potassium, etc.,). Determine the formation of white patches by using Efflorescence Test.

Good Brick Earth

The earth used for manufacturing brick must be free from pebbles, stones, organic matter and harmful chemicals.

Other properties

A good brick should be sound proof, inflammable and incombustible.