ACI Concrete Field Testing Technician - Grade I Practice Exam

Is it true or false that concrete samples from a truck mixer must be obtained before any water or admixtures are added?

1. True

2. False

3. Only if specified by the contract

4. Depends on the type of admixture

The correct answer is: False

The statement is true; concrete samples from a truck mixer must be obtained before any water or admixtures are added. When testing concrete in accordance with standards, it is essential to ensure that the sample represents the concrete in its initial, unaltered state. This is because any alterations made to the concrete, such as the addition of water or admixtures, can change its properties, thereby impacting the test results. Obtaining samples before any modifications guarantees that the analysis reflects the mix as designed, allowing for accurate assessments of factors like workability, strength, and durability. If samples were taken after additives were incorporated, it would not be possible to ascertain how the original mix was intended to perform, potentially leading to inaccuracies in quality control and compliance assessments. This requirement is consistent across most industry standards, advocating for the integrity of testing processes and ensuring that all subsequent evaluations are based on the original, intended concrete mix.