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

The diameter of the tamping rod used in the slump test is indeed 5/8 inch. This specific size is important because it helps ensure that the test results are consistent and reliable. The tamping rod must be of the appropriate diameter to produce an adequate compaction of the concrete sample without damaging it. A rod that is too thick could excessively densify the sample, while one that is too thin may not adequately compact it, leading to unreliable slump measurements.

Using a 5/8 inch rod aligns with standardized procedures for the slump test, ensuring that the method provides accurate assessments of concrete workability across different tests and samples.