ACI Certification Practice Exam

When sampling from a paving mixer, how many different portions are needed for a composite sample?

1. 3 different portions

2. 4 different portions

3. 5 different portions

4. 6 different portions

The correct answer is: 5 different portions

To create a composite sample from a paving mixer, it is essential to ensure that the sample accurately represents the material being produced. The correct answer indicates that five different portions are necessary for this composite sampling process. This requirement arises from the need for thoroughness in sampling; it allows for variability in the material being mixed to be effectively captured. In taking multiple portions, one can account for differences in consistency throughout the batch, ensuring that the composite sample reflects a true representation of the entire quantity of material. The process of combining these portions helps mitigate the risk of anomalies or outliers that might be present in a single sample, thus leading to more reliable testing results. Sampling five portions meets the standard practices in quality control and materials testing, making this approach widely accepted in the industry.