ACI Certification Practice Exam

Before the 25th stroke, what must be added when the top layer of concrete is low?

1. More water

2. More aggregate

3. Additional concrete

4. None of the above

The correct answer is: Additional concrete

When the top layer of concrete is low before the 25th stroke, it is essential to add additional concrete to maintain the proper level and ensure proper finishing. Adding more concrete helps achieve the designated thickness and prevents weak spots that could compromise the integrity and durability of the finished structure. This approach allows for uniformity in the final surface and supports the correct curing process, which is critical for achieving optimal strength and durability in the concrete. In this context, adding more water could lead to an overly fluid mixture, weakening the concrete's strength. Similarly, introducing more aggregate might not address the immediate issue of surface level and could adversely affect the concrete's mix ratios. Therefore, only the addition of concrete directly addresses the problem of the low surface while helping meet the necessary specifications for the project.