North Carolina Building Contractor License Practice Exam

What does the upward migration of water in freshly placed concrete refer to?

1. Bleeding

2. Seepage

3. Curing

4. Wicking

The correct answer is: Bleeding

The upward migration of water in freshly placed concrete is referred to as bleeding. This phenomenon occurs due to the settlement of the solid particles in the concrete mix, which causes the water, often referred to as pore water or bleed water, to rise to the surface. As the heavier solid particles settle to the bottom, the lighter water moves upward and collects on the surface. Understanding bleeding is essential because it can affect the surface finish and durability of the concrete. Excessive bleeding may lead to issues such as scaling, poor bonding with subsequent layers, or reduced strength due to a high water-cement ratio. The other terms presented do not accurately describe this specific process. Seepage typically refers to the movement of water through soil or materials, often due to pressure or gravity, and is not specific to the behavior of water in concrete mixtures. Curing is the process of maintaining adequate moisture, temperature, and time for concrete to achieve desired strength and durability. Wicking refers to the movement of moisture along materials due to capillarity and is not limited to conditions within concrete during placement. Thus, bleeding is the most appropriate term for upward water migration in freshly placed concrete.