Which statement correctly describes the purpose of dampening subgrade or wood forms before placing concrete?

Which statement correctly describes the purpose of dampening subgrade or wood forms before placing concrete?

• A. Prevent Rapid Extraction of the Mixing Water From the Concrete
• B. Cause a High Water / Cement Ratio And Greatly Reduce the Strength
• C. Promote Organic Growth And Should Be Avoided
• D. Cause an Excess of Surface Water to Appear After Floating

Answer: (A)

Dampening the subgrade or wood forms helps control moisture transfer between the fresh concrete and its immediate surroundings. When concrete is placed, it can draw water out into dry forms or a dry subgrade through suction and capillary action. If the forms or substrate are dry, they wick water from the concrete rapidly, which lowers the mix’s slump, reduces workability, and can lead to surface issues or premature stiffening. Pre-wetting the forms and subgrade minimizes that suction, keeps the concrete moisture more uniform, helps maintain the intended consistency and finishing quality, and supports proper strength development. The other statements describe undesirable or unrelated effects: increasing the water-cement ratio would weaken the concrete; promoting organic growth is not relevant to form dampening; and creating excess surface water after floating is not the purpose of dampening and would indicate other issues like bleeding.

Dampening the subgrade or wood forms helps control moisture transfer between the fresh concrete and its immediate surroundings. When concrete is placed, it can draw water out into dry forms or a dry subgrade through suction and capillary action. If the forms or substrate are dry, they wick water from the concrete rapidly, which lowers the mix’s slump, reduces workability, and can lead to surface issues or premature stiffening. Pre-wetting the forms and subgrade minimizes that suction, keeps the concrete moisture more uniform, helps maintain the intended consistency and finishing quality, and supports proper strength development.

The other statements describe undesirable or unrelated effects: increasing the water-cement ratio would weaken the concrete; promoting organic growth is not relevant to form dampening; and creating excess surface water after floating is not the purpose of dampening and would indicate other issues like bleeding.