Canadian Council of Independent Laboratories (CCIL) Practice Exam 2025 – All-in-One Comprehensive Guide to Exam Success!

For testing a slump flow sample, it is essential to sieve off the material retained on a 28mm sieve before conducting the test. This step is crucial because slump flow tests are designed to evaluate the workability of a concrete mixture, and larger aggregates can significantly impact the results. By removing particles that are larger than 28mm, the sample is standardized to ensure that the test measures the flowability of the concrete without interference from oversized aggregates. This process allows for a more accurate assessment of the concrete’s consistency and performance in scenarios like pumping or placement.

The other options do not correctly address the requirements for preparing a slump flow sample. For instance, using a larger sieve would not be appropriate since the goal is to eliminate larger aggregates, not capture them. Mixing the sample thoroughly is a good practice for homogeneity but is not specific to the slump flow sample preparation. Keeping the sample in a refrigerator is not relevant to the preparation of the slump flow test, as this could potentially alter the properties of the concrete mixture.