A Reinforced concrete structure has to be constructed along sea coast. The minimum grade of concrete to be used as per IS 456-2000
- AM15
- BM20
- CM25
- DM30Correct
Solution
Concept
Minimum concrete grade for coastal exposure
Formula
NONE
Step-by-step solution
1. A reinforced concrete structure built along a sea coast is subject to severe exposure conditions. 2. IS 456-2000 Table 5 details durability requirements including minimum concrete grade for varying exposures. 3. For severe exposure in RCC structures, the minimum recommended grade of concrete is M30. Answer: D
Explanation
Structures built along a sea coast are classified under severe environmental exposure conditions according to IS 456-2000. For severe exposure, the code mandates a minimum concrete grade of M30 for reinforced concrete to resist coastal chemical attacks and chloride-induced corrosion. This ensures long-term structural integrity and adequate durability in marine environments.
Why the other options are wrong
A) M15 is not permitted for structural RCC under IS 456-2000. B) M20 is the minimum grade for RCC under mild exposure conditions. C) M25 is the minimum grade for RCC under moderate exposure conditions.
Shortcut
Sea coast exposure is Severe = Minimum M30 grade for RCC.
Common mistake
Confusing the minimum concrete grade for RCC (M30) with plain concrete (M20) in sea coast exposure.
Correct answer: D) M30