Red Seal Carpenter Practice Exam

What is one critical step to ensure proper curing of concrete?

1. Place a polyethylene barrier on the ground before concrete placement.

2. Place a polyethylene barrier on the ground and wet it before concrete placement.

3. Place a polyethylene sheet immediately on top of the freshly finished concrete so it does not have a chance to dry out.

4. Place dry burlap on top of the freshly finished concrete and spray it with water an hour later so the concrete can begin to set up.

The correct answer is: Place a polyethylene sheet immediately on top of the freshly finished concrete so it does not have a chance to dry out.

Proper curing of concrete is critical for its long-term strength and durability. When newly poured concrete is exposed to air, it begins to lose moisture through evaporation which can result in cracking and weakening of the concrete. Option A is incorrect because while placing a polyethylene barrier can prevent the ground from absorbing moisture from the concrete, it does not directly address the issue of evaporation. Option B is incorrect because while wetting the polyethylene barrier can slow down the process of evaporation, it may not fully prevent it. Option D is incorrect because while wetting the burlap can provide moisture for the concrete, it is not as effective as directly placing a polyethylene sheet on top of the concrete to prevent it from drying out. Therefore, option C is the critical step as it directly addresses the issue of evaporation by creating a barrier between the concrete and the air.