What is the purpose of on-site sampling in relation to acceptance criteria?

• A. To verify only color match with project design.
• B. To replace the need for cylinder tests.
• C. To verify the concrete properties meet project specifications and document compliance or discrepancies.
• D. To schedule curing time.

Answer: (C)

On-site sampling is used to verify that the concrete being placed meets project specifications and to document whether it complies or shows discrepancies. By collecting representative samples at the job site, field tests can check the properties specified in the mix design and contract, such as slump, air content, temperature, and ultimately strength through cylinder tests. These results provide the evidence for acceptance decisions: if the tests meet the acceptance criteria, the concrete is accepted; if they don’t, any deviations are documented and corrective actions are taken. This process does not replace the need for cylinder tests; it works alongside them to provide the necessary field data. Color is not the defining factor for acceptance, since structural and durability properties drive the decision. Scheduling curing time is determined by the project requirements and conditions, not by the sampling itself.