Canadian Council of Independent Laboratories (CCIL) Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

The correct choice specifies the required sampling interval from a mixer or truck agitator when obtaining a concrete sample. In the context of concrete sampling, obtaining a representative sample is critical to ensure that testing reflects the actual composition and properties of the entire batch.

Sampling from 10% to 90% of the concrete load captures the mid-range of the material, which is essential because it allows for the collection of a sample that consists of well-mixed concrete, avoiding the potentially less homogeneous material at the very start or the end of the discharge process. Sampling at the beginning (0% to 10%) may result in material that hasn't been fully mixed, while sampling at the very end (90% to 100%) runs the risk of obtaining concrete that has started to segregate or is otherwise not representative of the whole batch.

This approach is aligned with standard practices in concrete testing, where the aim is to minimize the effects of segregation and differential mixing that can occur during the loading and mixing process. As a result, the sampled concrete more accurately represents the entire volume rather than isolated sections that may not be reflective of the entire material.