For the slump test, the ends of the tamping rod must be which shape?

For the slump test, the ends of the tamping rod must be which shape?

• A. Be flat
• B. Be chamfered
• C. Be pointed
• D. Be hemispherical rounded

Answer: (D)

In a slump test, the tamping rod is used to consolidate the concrete inside the slump cone after each lift, and the contact ends must be hemispherical rounded. This shape provides gentle, even contact that distributes force without gouging or tearing the surface, which would bias the measured slump by altering the surface profile or volume displaced. A flat, pointed, or chamfered end could create marks, channels, or additional compaction in localized areas, introducing variability in the test result. The rounded ends ensure a consistent, repeatable consolidation that yields an accurate slump measurement.

In a slump test, the tamping rod is used to consolidate the concrete inside the slump cone after each lift, and the contact ends must be hemispherical rounded. This shape provides gentle, even contact that distributes force without gouging or tearing the surface, which would bias the measured slump by altering the surface profile or volume displaced. A flat, pointed, or chamfered end could create marks, channels, or additional compaction in localized areas, introducing variability in the test result. The rounded ends ensure a consistent, repeatable consolidation that yields an accurate slump measurement.