Correct option is C
The minimum clear cover to the main steel bars in structural elements is specified in IS 456:2000 (Code of Practice for Plain and Reinforced Concrete). The values depend on the type of structural element and exposure conditions:
Slab:
Minimum clear cover: 20 mm (for mild exposure conditions).
This ensures adequate protection for the reinforcement against corrosion and fire.
Beam:
Minimum clear cover: 25 mm.
Beams are larger structural members and require a greater cover for durability.
Column:
Minimum clear cover: 40 mm.
Columns are vertical members subjected to compression and require a higher cover for protection against fire and environmental effects.
Footing:
Minimum clear cover: 50 mm.
Footings are in direct contact with soil, and a larger cover is essential for durability and to prevent reinforcement corrosion due to moisture and soil chemicals.
