The minimum grade of concrete for moderate exposure with normal weight aggregates is
- AM 15
- BM 20
- CM 25Correct
- DM 35
Solution
Concept
Minimum cement and grade for exposure
Step-by-step solution
1. IS 456 Table 5: mild M20; moderate M25; severe M30; very severe M35; extreme M40.
Explanation
Higher exposure demands a higher grade of concrete for durability.
Why the other options are wrong
M15 and M20 are below the minimum, and M35 is for very severe exposure.
Shortcut
Mild 20, Moderate 25, Severe 30, V. severe 35, Extreme 40.
Common mistake
Choosing M20.
Correct answer: C) M 25