Efflorescence is the usual sulphate of magnesium, calcium, sulphate and carbonate (and sometimes chloride and nitrates) of sodium and potassium terms for deposit of soluble salts, formed in or near the surface of a porous material, as a result of evaporation of water in which they have been dissolved.
EFFLORESCENCE TEST OF BRICK
OBJECTIVE
To determine the efflorescence of the brick.
EQUIPMENT AND MATERIAL
1) Distilled water
2) Bricks sample to be tested for efflorescence.
3) Flat bottom shallow dish made up of glass, porcelain or glazed stoneware having following details
For square dish :- width- 180 mm
length- 180 mm
depth- 40 mm
For circular dish :- Depth = 40 mm
Diameter- 200 mm
4) Glass cylinder
5) Oven
PROCEDURE
1) Fill distilled water in shallow dish and placed the ends of the bricks are in the dish, the depth of immersion in water being 25 mm.
2) Placed the whole arrengment in a warm well ventilated room (between 200c and 300c) until all the water in the dish is absorbed by the specimens and the surplus water evaporates.
3) To avoid the excessive evaporation from the dish, the dish containing the brick cover with suitable glass cylinder.
4) When the water has been absorbed and bricks appear to be dry, a similar quantity of water is placed in the dish and it is allowed to evaporate as before. Examine the bricks for efflorescence after the second evaporation and report the results.
RESULTS REPORTED
Nil
When the deposit of efflorescence is imperceptible.
Slight
When the deposit of efflorescence does not cover more than 10 per cent of the exposed area of the brick.
Moderate
When the deposit of efflorescence is more than 10 per cent but less than 50% of the exposed area of the brick.
Heavy
When the deposit of efflorescence is more than 50 per cent but the deposits do not powder or flake away the brick surface.
Serious
When the deposits are heavy and powder or flake away the brick surface.
The specifications limit the efflorescence to be not more than moderate (10–50%) up to class 12.5 and not more than slight (< 10 per cent) for higher classes.
TREATMENT OF EFFLORESCENCE
The soluble salts can be removed by frequent repeated washings with clean water and brushing the face of the masonry. The salts from brickwork can also be removed with a solution of zinc sulphate and water. For this application, the surface that has to be treated should be brushed off thoroughly and allowed to dry. A solution containing 1 part of hydrochloric acid or sulphuric acid with 5 parts of water is applied vigorously with scrubbing brushes and water is being constantly sprayed on the work with a hose to prevent the penetration of acid. By doing so, this helps in removing white or yellow blotches from floors or walls due to efflorescence.
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