ACI Certification Practice Exam

What is the significance of rapid evaporation when obtaining a concrete sample?

1. It improves sample quality

2. It can lead to inaccurate test results

3. It is unimportant

4. It helps in mixing

The correct answer is: It can lead to inaccurate test results

The significance of rapid evaporation when obtaining a concrete sample lies primarily in its potential to lead to inaccurate test results. When concrete samples are exposed to rapid evaporation, especially in warm or windy conditions, the moisture content of the sample can decrease significantly before testing takes place. This loss of water can alter the physical and chemical properties of the concrete, resulting in misleading test outcomes. For instance, testing a sample that has lost water can yield incorrect measurements of workability, strength, and other performance characteristics. Understanding this impact is critical in ensuring that concrete samples reflect their actual intended properties. Proper handling and curing techniques are essential to maintain the moisture content until testing is conducted, thereby ensuring that the results obtained are reliable and representative of the concrete as it would perform in its final application.