What does a slump test measure?

• A. Air content
• B. Compressive strength
• C. The workability or consistency of fresh concrete
• D. Water-cement ratio

Answer: (C)

The test is about how workable or flowable the fresh concrete is. In the slump test, a standard cone is filled with freshly mixed concrete, lifted away, and the amount the concrete subsides is measured. A larger subsidence means a more workable, looser mix, while little or no subsidence means a stiffer mix. This directly reflects the consistency and ease of placement and finishing for that batch.

Air content isn’t measured by this test—it's determined with an air meter or similar device and relates to the amount of air voids in the hardened concrete. Compressive strength is tested on cured specimens (like cylinders) after a set period, not from a fresh-mixture slump. The water-cement ratio is a design property of the mix proportions; while the slump can be affected by water content, the slump test itself does not measure the actual W/C ratio.