ACI Concrete Field Testing Technician - Grade I Practice Exam

What is the diameter of the tamping rod used in the slump test?

1. 1/2 in. [13 mm]

2. 5/8 in. [16 mm]

3. 3/4 in. [19 mm]

4. 7/8 in. [22 mm]

The correct answer is: 5/8 in. [16 mm]

The diameter of the tamping rod used in the slump test is 5/8 in. [16 mm]. This specification is critical to achieving consistent results in the slump test, as the rod's diameter must be appropriate for effectively compressing the concrete sample without affecting the test outcome. A rod that is too thin may not adequately compact the concrete, while one that is too thick could lead to excessive density and skewed results. In the context of the slump test, the tamping rod is utilized to strike the concrete in a specific manner, ensuring that it is properly consolidated in the cone mold. The specified diameter helps maintain standardization across different testing scenarios, thereby creating reliable benchmarks for assessing concrete consistency. Each size has been tested for its impact on the results, and 5/8 in. [16 mm] has been determined to provide optimal performance within established testing guidelines.