What are the required characteristics of the tamping rod used in the concrete testing method?

The required characteristics of the tamping rod used in the concrete testing method are outlined in standard testing procedures. Specifically, the tamping rod must be a round, smooth, and straight steel rod with dimensions that meet the specified requirements, typically around 16 mm in diameter and 610 mm in length. This design ensures that the rod can effectively consolidate the concrete mix without deforming or leaving any imprint that might affect the density measurement.

Using a smooth surface prevents the rod from adhering to the concrete, allowing for consistent and reliable compaction. These characteristics are crucial in maintaining uniformity in testing and achieving accurate results when measuring the workability or density of concrete mixtures. The other options, such as a flat steel rod, a flexible rubber rod, or a wooden rod, do not conform to the established standards and would not provide the necessary functionality or consistency required for effective concrete testing.