Core samples are used in concrete testing for what purpose, in relation to cylinder tests?

• A. Core samples are used for determining slump.
• B. They are used when in-situ strength verification is needed or cylinder results are inconclusive; cores provide direct in-place strength data.
• C. They completely replace cylinder tests.
• D. They are used to determine the water-cement ratio.

Answer: (B)

Core samples are used to verify the actual strength of concrete in the place where it was put, especially when there are questions about cylinder test results. They provide direct, in-situ strength data from the concrete as it cured and hydrated in the structure, which helps confirm whether the concrete meets the required strength when the standard cylinder results are inconclusive or suspect. They’re a supplemental check rather than a universal replacement for cylinder tests. Slump testing and determining the water-cement ratio come from different aspects of the concrete: slump assesses fresh concrete consistency, and the water-cement ratio is a mix-design characteristic, not something you derive from core strength.