Question

As per IS 456 ∶ 2000, the minimum grade of concrete to be used for plain concrete and reinforced concrete, respectively, in concrete works exposed directly along the sea coast are:
1. M20 and M30
2. M15 and M25
3. M25 and M40
4. M20 and M25

Answer 1

Correct Answer - Option 1 : M20 and M30

Explanation:

Concrete in Sea-water (as per IS 456: 2000)

Concrete in sea-water or exposed directly along the sea-coast shall be at least M 20 Grade in the case of plain concrete and M 30 in case of reinforced concrete.

The use of slag or pozzolana cement is advantageous under such conditions.

Exposure	Minimum grade of  Plain Concrete	Minimum grade of  reinforced concrete
Mild	-	M20
Moderate	M15	M25
Severe	M20	M30
Very severe	M20	M35
Extreme	M25	M40