NASCLA Accredited Commercial General ContractorConcreteEasy
A concrete contractor is preparing to pour a concrete slab for a commercial building. The specifications require a minimum compressive strength of 4,000 psi at 28 days. Which of the following tests is performed on fresh concrete to assess its workability and consistency, but does not directly measure its strength?
- AFlexural strength test
- BRebound hammer test
- CSlump test
- DCompression test
Show answer & explanationAnswer & explanation
Correct answer: C. Slump test
The slump test is a common method used to determine the workability and consistency of fresh concrete. It does not provide a direct measure of the concrete's compressive or flexural strength, which are typically determined by other tests after the concrete has hardened.
Why the other options are wrong
- A. Flexural strength tests measure the tensile strength of hardened concrete in bending.
- B. The rebound hammer test is a non-destructive test used on hardened concrete to estimate its compressive strength.
- D. Compression tests are performed on hardened concrete cylinders to measure compressive strength.
Slump Test
A test performed on fresh concrete to measure its consistency and workability, indicating how fluid or stiff the mix is.
- Measures workability, not strength.
- Uses a truncated cone mold.
- Result is measured by how much the concrete 'slumps' after the cone is removed.
Memory trick: Fresh as a Daisy, Slump away lazy.