Red Seal Concrete Finisher Practice Exam

What does "setting time" refer to in concrete work?

1. The time it takes for concrete to fully cure

2. The period it takes for concrete to harden sufficiently to be walked on

3. The duration required for morning dew to evaporate

4. The time needed for aggregates to bond with cement

The correct answer is: The period it takes for concrete to harden sufficiently to be walked on

Setting time in concrete work specifically refers to the period it takes for concrete to harden enough to support weight, typically to the point where it can be walked on. This is a crucial phase in the concrete curing process, as it indicates when the concrete has reached a level of stiffness that allows for the safe movement of personnel and equipment over its surface. During the setting time, the initial chemical reactions between water and cement begin to take place, which leads to the formation of a solid mass. This timeframe is important for planning purposes, as it determines when subsequent construction activities can commence without damaging the fresh concrete. Other options, like the curing process or environmental factors like dew evaporation, do not specifically define the setting time but are related to the overall behavior and treatment of concrete during and after the pouring phase. The bond between aggregates and cement is part of the hydration chemistry but occurs over a longer duration than the initial setting time.