Bricks MCQ with answer and solution

Concept

Water absorption test measures the porosity and quality of bricks; lower absorption indicates better quality and higher strength.

Step-by-step solution

1. Weigh the dry brick (W1). 2. Immerse the brick in water for 24 hours. 3. Weigh the wet brick (W2). 4. Calculate water absorption percentage as ((W2 - W1) / W1) × 100. 5. For first-class bricks, this value must not exceed 15%.

Explanation

According to IS 1077, first-class bricks should have a water absorption of not more than 15% of their dry weight after 24 hours of immersion in cold water. This ensures good strength, durability, and resistance to weathering.

Why the other options are wrong

A: 10% is too stringent and generally not required for standard first-class bricks. C: 20% is the permissible limit for second-class bricks. D: 25% is the permissible limit for third-class bricks.

Shortcut

Remember the sequence for brick classes: 1st class = 15%, 2nd class = 20%, 3rd class = 25%.

Common mistake

Confusing first-class brick water absorption (15%) with second-class (20%) or third-class (25%).