ACI Concrete Field Testing Technician - Grade I Practice Exam

If the concrete sample is to be consolidated by rodding, how many layers should the measure be filled with?

1. 1 thick layer

2. 2 equal layers

3. 3 equal layers

4. 4 uneven layers

The correct answer is: 3 equal layers

When consolidating concrete by rodding in a standard cylindrical measure, the procedure involves filling the measure with three equal layers. This method is essential for ensuring uniformity and consistency in the sample. Each layer should be rodded a specified number of times (typically 25 times) to thoroughly consolidate the concrete and eliminate any air pockets, which might affect the density and strength of the cured concrete. Filling the measure with three equal layers is the standard procedure outlined in ASTM standards, which ensures that the concrete is evenly mixed and that the test results are reliable. This approach not only facilitates the removal of air bubbles effectively but also allows for better representation of the concrete's properties. Using one thick layer would not sufficiently consolidate the concrete, leading to improper testing results due to trapped air. Two equal layers may not provide enough variation for proper mixing and consolidation. Four uneven layers would complicate the process and potentially result in an inconsistent sample, which might not accurately reflect the properties of the concrete mixture being tested. Thus, adhering to the three equal layers method is crucial for achieving accurate and reliable test results.