Dampening of the subgrade or the wood concrete forms prior to the placement of concrete will have which effect?

Dampening of the subgrade or the wood concrete forms prior to the placement of concrete will have which effect?

• A. promote organic growth and should be avoided
• B. cause a high water/cement ratio and greatly reduce the strength of the concrete
• C. prevent rapid extraction of the mixing water from the concrete
• D. cause an excess of surface water to appear after floating

Answer: (C)

Moisture movement between fresh concrete and the surrounding surfaces matters because proper curing depends on keeping enough water in the mix during early hydration. Dampening the subgrade or wood forms reduces their tendency to pull water out of the concrete. With less rapid moisture loss at the surface, the concrete retains its mixing water longer, minimizing plastic suction, reducing surface drying, and supporting better curing and strength development. This is why preventing rapid extraction of the mixing water is the best description of the effect. The other ideas don’t fit: dampening doesn’t promote organic growth, the mix’s water–cement ratio is not set by the dampness of the forms, and dampening doesn’t create excess surface water after finishing.

Moisture movement between fresh concrete and the surrounding surfaces matters because proper curing depends on keeping enough water in the mix during early hydration. Dampening the subgrade or wood forms reduces their tendency to pull water out of the concrete. With less rapid moisture loss at the surface, the concrete retains its mixing water longer, minimizing plastic suction, reducing surface drying, and supporting better curing and strength development. This is why preventing rapid extraction of the mixing water is the best description of the effect. The other ideas don’t fit: dampening doesn’t promote organic growth, the mix’s water–cement ratio is not set by the dampness of the forms, and dampening doesn’t create excess surface water after finishing.