North Carolina Building Contractor License Practice Exam

What is the minimum concrete cover (in inches) for a W31 piece of rebar when using high-early strength concrete on a patio slab?

1. 4

2. 6

3. 8

4. 10

The correct answer is: 6

The minimum concrete cover for reinforcement, such as a W31 piece of rebar, is essential for ensuring the durability and performance of the concrete structure. In general, concrete cover protects the rebar from corrosion, helps maintain structural integrity, and influences the bond between the concrete and the reinforcement. In the context of high-early strength concrete, which is often used in situations where a quick set time is required, the specified minimum concrete cover can be different than for normal concrete. According to typical building codes and practices, a minimum cover of 2 inches is often required for slabs that are at ground level under standard conditions. However, when dealing specifically with high-early strength concrete, which may allow for more rapid exposure to environmental factors, a greater concrete cover is frequently recommended. The option of 6 inches for minimum concrete cover in this context aligns with standard best practices for high-early strength concrete. This depth ensures adequate protection against cracking and environmental exposure, while still providing the necessary structural support for the patio slab. In summary, the requirement of 6 inches is consistent with building codes that prioritize reinforcement protection and structural longevity, especially under the conditions that high-early strength concrete presents.