Durability and Cover MCQ with answer and solution

Concept

Minimum cement content for mild exposure

Formula

NONE

Step-by-step solution

1. IS 456-2000 Table 5 prescribes minimum cement content based on structural concrete type and exposure severity. 2. For reinforced concrete subjected to mild exposure conditions, the minimum cement content is specified as 300 kg/m³. 3. This minimum requirement ensures long-term structural durability and protection of reinforcement. Answer: D

Explanation

According to IS 456-2000 Table 5, the minimum cement content specified for reinforced concrete subjected to mild exposure conditions is 300 kg/m³. This requirement ensures basic durability and adequate alkalinity to protect the embedded steel reinforcement from corrosion. Using less cement reduces durability and exposes steel to structural degradation over time.

Why the other options are wrong

A) 150 kg/m³ is insufficient for reinforced concrete structures. B) 250 kg/m³ is the minimum cement content for plain concrete under mild exposure. C) 350 kg/m³ is the minimum cement content required for extreme exposure conditions.

Shortcut

Minimum cement content for RCC mild exposure = 300 kg/m³.

Common mistake

Confusing the minimum cement content for RCC (300 kg/m³) with that of plain concrete (220 kg/m³).