How much water should be placed in the dish initially?

Distilled water to a depth of 25 mm (Clause 4.1).

How many evaporation cycles are required?

Two cycles. After the first complete evaporation, a similar quantity of water is added and allowed to evaporate again (Clause 4.1).

What constitutes 'Moderate' efflorescence?

Salt deposits covering between 10% and 50% of the exposed area without any powdering or flaking of the surface (Clause 5.1.3).

What is the acceptable limit of efflorescence for common bricks as per IS 1077?

Usually 'Moderate' up to class 12.5, and 'Slight' for higher classes, but one must refer to IS 1077 for exact compliance.

IS 3495 Part 3

: 1992

Methods of Tests of Burnt Clay Building Bricks: Part 3 Determination of efflorescence

CurrentFrequently UsedTesting MethodMaterials Science · Masonry and Bricks

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This standard specifies the laboratory test method to determine the efflorescence in burnt clay building bricks by evaluating the surface deposition of soluble salts after cycles of distilled water absorption and evaporation.

Specifies the procedure for determining the efflorescence of burnt clay building bricks.

Quick Reference Values

depth of water in dish25 mm

room temperature for test20 to 30°C

nil efflorescence0% (No perceptible deposit)

slight efflorescenceNot more than 10% of exposed area

moderate efflorescence10% to 50% of exposed area (no flaking)

heavy efflorescenceMore than 50% of exposed area (no flaking)

serious efflorescenceHeavy deposits accompanied by powdering/flaking

Practical Notes

Strictly use distilled water; using tap water introduces external salts leading to false positive efflorescence results.

Ensure the test is conducted in a well-ventilated room to facilitate proper natural evaporation.

The crucial distinction between 'Heavy' and 'Serious' efflorescence relies on whether structural degradation (flaking or powdering of the brick) occurs.