NASCLA Commercial Building Practice Exam 2025 – Comprehensive Prep Guide

The additive that can shorten the setting time or produce high early strengths in concrete is an accelerator. Accelerators are chemical additives that are mixed with concrete to speed up the hydration process, which decreases the time it takes for the concrete to set and reach strength. This can be particularly beneficial in cold weather conditions or when rapid construction schedules are in place.

Using accelerators allows for quicker completion of concrete works, improving the overall efficiency of construction projects. They enhance the early strength development of the concrete, allowing for earlier form removal and faster placement of subsequent layers or construction activities. Typical examples of accelerators include calcium chloride and non-chloride accelerators that help facilitate faster curing.

In contrast, other options like retarders are used to delay the setting time, while water reducers improve workability without impacting the setting time significantly. Fiber reinforcement primarily serves to enhance the structural integrity and toughness of concrete, though it does not directly influence the setting time or early strength significantly.