North Carolina Building Contractor License Practice Exam

What should be done if the relative humidity falls below the required level during concrete curing?

1. Increase the cement content

2. Use additional water

3. Provide cover to retain moisture

4. Apply curing compound

The correct answer is: Provide cover to retain moisture

During concrete curing, it's essential to maintain the right moisture levels to ensure proper hydration of the cement. When the relative humidity falls below the required level, providing cover to retain moisture is an effective method to combat the drying effects of the environment. This can be achieved through the use of wet burlap, plastic sheeting, or similar materials that help keep the surface of the concrete moist. This approach prevents the concrete from drying out too quickly, which can lead to cracking and weaken the final strength of the concrete. Keeping the curing environment as steady as possible supports the chemical reactions necessary for the concrete to achieve its designed strength and durability. In contrast, simply increasing the cement content or using additional water may not adequately address the issue of moisture loss. While applying a curing compound can help form a film to retain moisture, it does not directly solve the problem of low relative humidity as effectively as providing a cover. Using a cover creates a controlled environment that directly addresses the main concern of moisture retention during the crucial curing period.