Question

In case of good quality bricks, absorption of water should be more than _______ of its weight after immersion in water for 16 hours.

• A. 10 %
• B. 20 %
• C. 30 %
• D. 40 %

Hint:

Low water absorption = High durability. For standard first-class bricks, 20% is the "magic number" to remember.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
This question pertains to Dairy Plant Engineering and construction materials.
Bricks used for dairy plant construction must be durable and resistant to moisture.
Water absorption is a key test to determine the quality and porosity of a brick.

Step 2: Detailed Explanation:
According to standard civil engineering codes (like IS: 1077 in India), bricks are classified based on their compressive strength and water absorption properties.
For a "First Class" or good quality building brick:
1. The water absorption should not exceed 20% of its dry weight after being immersed in water for 24 hours (or sometimes specified as 16 hours in older texts).
2. If the absorption is less than 20%, it indicates a dense, well-burnt brick that will not allow moisture to seep through walls, which is essential for maintaining hygiene in a dairy plant.
In the context of the question's phrasing, "absorption ... should be more than" usually implies the upper limit or the threshold of a specific class.
If a brick absorbs 30% or 40% (Options 3 and 4), it is considered porous and low-quality, likely to fail in damp environments.
If it absorbs only 10% (Option 1), it is an exceptionally high-grade engineering brick (Class AA).
The standard benchmark for "good quality" building bricks is the 20% mark.

Step 3: Final Answer:
The standard value is 20 %.