Which term describes concrete that has begun to stiffen and lose workability?

• A. Set
• B. Bleed
• C. Set or stiffening
• D. Slump loss

Answer: (C)

As concrete hydrates, it shifts from a workable plastic state to a stiffer, less workable one. This transition is described by the term set, with initial set marking the start of stiffening and final set when the concrete becomes firm enough to resist surface shaping. “Stiffening” is a natural way to describe what you’re observing. So, the condition described—concrete that has begun to stiffen and lose workability—fits the phrase set or stiffening.

Bleed refers to water rising to the surface, not to a change in workability. Slump loss describes a decrease in workability over time, but it’s about the change in slump rather than the concrete’s current state. The option that combines set and stiffening best captures the situation.