Efflorescence of brunt clay Bricks

When the brick earth contains an excess amount of alkaline salts, after absorbing moisture from the atmosphere and on drying it leaves a greenish white deposit on the surface of the brick. The Efflorescence test is performed as per IS 3495 Part 3 to know the presence of alkaline matter in the bricks using a shallow flat bottom dish containing sufficient distilled water to completely saturate the brick.

Procedure:

1. Take the sample as per IS 5454, for a brick lot of 2001 to 10000, 5 bricks are taken as sample.
2. Place the end of the brick in the dish, the depth if the immersion being not less than 25 mm.
3. Place the whole arrangement in a warm $(\text{20 to 30}^\circ {C})$ well ventilated room untill all the water in the dish is absorbed by the brick, cover the whole arrangement with suitable glass cylinder to arrest the excess evaporation of water.
4. When all the water has been abosorbed and the brick appears to be dry, place a smiliar quantity of water in the dish and allow it to evaporate as before.
5. Examine the brick after the second evaporation and report the results.

The liability to efflorescence is recoreded in-accordance with the following standards:

Liability	Definition
Nil	When there is no perceptible deposit of efflorescence.
Slight	When not more than 10% of the exposed area of the brick is covered with a thin deposit of salts
Moderate	When there is a heavier deposit than under "slight" covering up to 50% of the exposed area of the brick surface but unaccompanied by powdering or flaking of the surface.
Heavy	When there is a heavy deposit of salts covering 50% or more of the exposed area of the brick surface but unaccompanied by powdering or flaking of the surface.
Serious	When there is a heavy deposit of salts accompanied by powdering and/or flaking of the exposed surface.

The rating of efflorescence shall not be more than "moderate" upto class 12.5 and "slight" for higher classes.

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