Test procedure and Acceptance criteria of bricks for building construction

The following tests are frequently performed before accepting the bricks for building construction.

1. Compressive Strength Test.
2. Water absorption Test.
3. Dimension and Tolerance Test.
4. Efflorescence Test.

Compressive strength test
• Approximate 6 no brick required to be taken from random sampling.
• The bricks must be submerged /immersed into the water at room temperature for 24 hours.
• After take out the bricks from the water surplus and excess water required to be removed from surfaces.
• Voids must be filled with cement sand mortar of ratio(1:1).
• Bricks must be stored in gunny bag for 24 hours and there after immerse them into the water for 72 hours.
• After that, bricks take out from water and wipe off dry, then and hollow portion must be filled with cement
mortar and bring to it in compressive testing machine.
• By application of load at a rate of 140 kg/cm2 per minute till the brick fails.
• The average value of compressive strength of all the bricks required to be taken.
• Generally the compressive strength of a common brick should be 50 kg/cm2.

Water absorption test

This test is required to determine the water absorption level of the brick. If the water absorption capacity of the brick is more , then strength of the brick is comparatively low.
• Select six no of brick as a random sample.
• Now dry all the bricks in a oven at a temperature of 100o to 120o C.
• After that all the bricks must be removed from oven and cool them in a room temperature.
• Average bricks weight is taken as W1.
• Now bricks must be immerse in water at a temperature of 27o+/- 2C for 24 hrs.
• After removing the brick from water surface cleaned by cloth.
• Now average weight of brick taken W2.
• So water absorption capacity= W2 – W1 / W1 X 100.
• In case of 1st class brick water absorption capacity should not be more than 20%.

Dimension and tolerances test

First Class Bricks

These are well burnt brick, having plain and even surfaces. Out side appearance is dark reddish colour and good rectangular shape. Whenever two bricks are struck heavy metallic sound rings. Its water absorption capacity is less than 20%.

Second Class Bricks

The shape of the brick is not perfectly rectangular. Surface is not so smooth, but comparatively hard.
It is slightly over burnt and almost equivalent colour in all sides. Metallic ringing sound has come with strucking to each other. Water absorption capacity should not be more than 22%.Little portion efflorescence has observed.

Third Class Bricks

These bricks are not burnt properly , either under burnt or over burnt. It is comparatively not hard and broken down easily with hard struck. The colour of the brick is red and yellowish. Water absorption capacity should not be more than 25%.
Moderate efflorescence has been observed in this type of brick.

Jhama Brick or Over burnt Brick

Due to excessive heat and temperature these bricks get over burnt. Shape has been lost and twisted and form bluish and blackish colour.

Test procedure

• Few no of brick sample has been taken.
• Proper dimension required to be measure as per standard specification.

Efflorescence Test

This test has been performed to know the alkali percentage present in the brick.

• Randomly few no of brick sample has been taken.
• Bricks are immersed into the distilled water at a temperature of 20o to 30oC till the water has been evaporated.
• Again the same process is repeated .
• If any precipitation has been observed then efflorescence may exist.

Stack of 1st class brick