How many strokes of the tamping rod are required when performing a slump test?

In a slump test, the purpose of using a tamping rod is to effectively consolidate the concrete mix within the mold before measuring the slump. The standard procedure stipulates that 25 strokes with the tamping rod are required. This specific number ensures that the concrete is adequately compacted, eliminating any air pockets that may affect the slump measurement. By following this guideline, you achieve consistency in the test results, thereby making it easier to compare the workability of different concrete mixtures.

The 25 strokes also serve to disturb the concrete uniformly, allowing for accurate results that represent the true flow and workability of the mix. This systematic approach is essential in construction and quality control to assess the performance of concrete in various applications, leading to safer and more reliable structures.