North Carolina Building Contractor License Practice Exam

What is the minimum relative humidity required for curing concrete to continue effectively?

1. 50 percent

2. 70 percent

3. 80 percent

4. 90 percent

The correct answer is: 80 percent

The minimum relative humidity required for curing concrete to continue effectively is 80 percent. Maintaining proper humidity levels is crucial in the curing process because it significantly affects the hydration of the cement particles within the concrete mix. Sufficient humidity helps to prevent the concrete from drying out too quickly, which can lead to cracking and weaken the final product. When humidity levels are at or above 80 percent, the conditions are generally optimal for curing. This humidity level inhibits rapid moisture loss from the surface of the concrete, allowing it to hydrate adequately and strengthen over time. While lower humidity levels might still allow for some curing to occur, they do not provide the ideal environment for maximum strength and durability of the concrete. Thus, ensuring a humidity level of at least 80 percent is essential for effective curing processes.