Slump Test – what property does it primarily measure? In fresh concrete testing, the slump test is primarily a measure of which characteristic?

Introduction / Context:
The slump test is one of the simplest and most widely used field tests for fresh concrete. It provides a quick indication of how easily a mix can be placed and compacted without segregation. Distinguishing what slump actually measures prevents misuse of the result for properties it does not represent.

Given Data / Assumptions:

• Abrams cone apparatus with standard dimensions and procedure.
• Normal-weight, non-flowing concretes without special self-compacting behavior.
• Test performed on level, non-absorbent surface.

Concept / Approach:

Slump quantifies consistency/workability by measuring subsidence of the concrete after removing the cone. Higher slump indicates greater ease of placement, all else equal. It does not measure compressive or tensile strength directly, nor is it an impact test; correlations with strength are weak because admixtures can change slump without changing water–cement ratio.

Step-by-Step Solution:

Verification / Alternative check:

Standards specify slump ranges for different placement methods (paving, pumped concrete, heavily reinforced sections) precisely as a workability control.

Why Other Options Are Wrong:

Strength must be checked by cube/cylinder tests; impact value pertains to aggregate tests; setting time is determined by Vicat apparatus, not slump.

Common Pitfalls:

Using extra water to increase slump and inadvertently lowering strength; not re-mixing the sample before test; performing the test on a porous base.

Final Answer:

Consistency (workability)