Question:easy
What is the minimum grade of concrete recommended in coastal areas according to IS 456:2000?
What is the minimum grade of concrete recommended in coastal areas according to IS 456:2000?
Show Hint
For durability:
\[
\boxed{
\begin{array}{c|c}
\text{Exposure Condition} & \text{Minimum Grade} \\ \hline
\text{Mild} & \mathrm{M20}\\
\text{Moderate} & \mathrm{M25}\\
\text{Severe / Coastal} & \mathrm{M30}
\end{array}
}
\]
Updated On: Jul 23, 2026
- M20
- M25
- M30
- M15
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: Classifying the exposure.
IS 456:2000 groups exposure conditions as mild, moderate, severe, very severe and extreme. A coastal or marine structure is constantly attacked by chloride-laden moisture and salt spray, which puts it in the severe to very severe exposure bracket.
Step 2: What that exposure demands.
For such harsh exposure the concrete needs to be dense and impermeable so that chlorides cannot reach the reinforcement and trigger corrosion. The code ties this need directly to a minimum grade of concrete, and for coastal exposure that minimum is $\text{M30}$.
Step 3: Selecting the option.
Among M15, M20, M25 and M30, only M30 satisfies this durability requirement for coastal conditions.
\[ \boxed{\text{M30}} \]
IS 456:2000 groups exposure conditions as mild, moderate, severe, very severe and extreme. A coastal or marine structure is constantly attacked by chloride-laden moisture and salt spray, which puts it in the severe to very severe exposure bracket.
Step 2: What that exposure demands.
For such harsh exposure the concrete needs to be dense and impermeable so that chlorides cannot reach the reinforcement and trigger corrosion. The code ties this need directly to a minimum grade of concrete, and for coastal exposure that minimum is $\text{M30}$.
Step 3: Selecting the option.
Among M15, M20, M25 and M30, only M30 satisfies this durability requirement for coastal conditions.
\[ \boxed{\text{M30}} \]
Was this answer helpful?
0
Top Questions on Concrete
M20 concrete as per IS 456: 2000 refers to concrete with a design mix having
- GATE CE - 2023
- Civil Engineering
- Concrete
- Consider the beam section shown in the figure, with \( y \) indicating the depth of neutral axis (NA). The section is only subjected to an increasing bending moment. It is given that \( y = 18.75 \, {mm} \), when the section has not yielded at the top and bottom fibres. Further, \( y \) decreases to 5 mm, when the entire section has yielded. The shape factor of the section is ........ (rounded off to 2 decimal places).
\begin{center} \includegraphics[width=8cm]{53.png} \end{center} - Consider a reinforced concrete beam section of 300 mm width and 700 mm depth. The beam is reinforced with the tension steel of 2000 mm² area at an effective cover of 50 mm. Concrete in the tension zone is assumed to be cracked. Assume the modular ratio of 12 and Young's modulus of 200 GPa for steel. When the extreme fibre in the compression zone undergoes the strain of 0.0004 due to the applied bending moment, the stress in the steel (in MPa) is ..... (rounded off to the nearest integer).
Consider the beam section shown in the figure, with \( y \) indicating the depth of neutral axis (NA). The section is only subjected to an increasing bending moment. It is given that \( y = 18.75 \, {mm} \), when the section has not yielded at the top and bottom fibres. Further, \( y \) decreases to 5 mm, when the entire section has yielded. The shape factor of the section is ........ (rounded off to 2 decimal places).
- Want to practice more? Try solving extra ecology questions todayView All Questions