ACI Concrete Field Testing Technician - Grade I Practice Exam

What is the specified number of strokes required when rodding each layer of a concrete sample?

1. 15

2. 20

3. 25

4. 30

The correct answer is: 25

The specified number of strokes required when rodding each layer of a concrete sample is 25. This standard is established to ensure that the concrete is properly consolidated in the mold, which is critical for obtaining an accurate measurement of the mix's properties, such as its strength and workability. When performing this task, each layer of concrete is typically placed in the mold in increments, and rodding is used to eliminate air voids and ensure uniform compaction. The requirement of 25 strokes for each layer helps achieve a consistent and homogeneous sample, which ultimately leads to more reliable test results. This standardization is crucial in the field of concrete testing as it minimizes variability and enhances the reproducibility of test outcomes. Using fewer or excessive strokes can lead to either inadequate consolidation or over-compaction, both of which can significantly impact the test results and the quality assessment of the concrete mixture. Therefore, adhering to the established guideline of 25 strokes is essential for accurate and effective concrete field testing.