What would be considered overworking concrete?

• A. Too much water and fine material to the surface.
• B. Too little water and air entrainment.
• C. Excessive vibration after placement.
• D. Over-curing the concrete

Answer: (A)

Overworking concrete refers to the actions taken on freshly mixed concrete that can lead to problems with its surface and overall strength. The correct answer involves the process of manipulating the concrete too much, which can lead to an excess of water and fine material surfacing. When concrete is overworked, especially through excessive finishing techniques, it can cause bleed water—water that rises to the surface during the setting process—to mix with the surface aggregates. This can negatively affect the strength and durability of the final product, as the top layer may become weak or porous.

The idea of overworking indicates that there must be a balance in handling the concrete to ensure it sets correctly without compromising its integrity. This makes the first choice particularly insightful, as it directly addresses a common pitfall in concrete finishing.

In contrast, the other options highlight different issues associated with concrete work. Too little water and air entrainment focus on inadequate mixing and preparation, while excessive vibration after placement tends to concentrate on the potential for segregation of materials rather than surface issues. Over-curing reflects a concern for curing methods rather than the handling of fresh concrete.