NASCLA Accredited Commercial General ContractorConcreteEasy
A concrete technician is performing a slump test on a fresh concrete mix. The concrete cone is filled in three layers, and each layer is rodded 25 times. After the final rodding and striking off the top, the cone is lifted, and the concrete slumps. The measured slump is 4 inches. What does this slump value primarily indicate about the concrete mix?
- AIts workability and consistency.
- BThe water-cement ratio.
- CIts ultimate compressive strength.
- DThe air content of the mix.
Show answer & explanationAnswer & explanation
Correct answer: A. Its workability and consistency.
The slump test is a measure of the consistency or workability of fresh concrete, indicating how easily it can be placed and compacted without segregation.
Why the other options are wrong
- B. While related, the slump test does not directly measure the water-cement ratio; it's an indirect indicator of consistency.
- C. The slump test does not directly measure ultimate compressive strength; cylinder tests are used for that.
- D. The slump test does not measure the air content; an air meter is used for that purpose.
Slump Test Purpose
A test performed on fresh concrete to determine its consistency and workability.
- Measures the vertical drop of a molded concrete cone.
- Higher slump indicates higher workability (within limits).
- Used for quality control on site.
Memory trick: Slump for flow, Air for freeze, Unit for weight, Temp for set.