What must be done before testing concrete containing coarse aggregate over 1.5" in size?

In testing concrete that contains coarse aggregate larger than 1.5 inches, it is essential to perform wet sieving over a 1.5-inch sieve. This process ensures that the larger particles are appropriately separated from the smaller ones before any testing is conducted. Wet sieving helps in achieving a more uniform particle distribution and minimizes the risk of aggregate segregation, which can significantly affect the concrete's properties and the accuracy of testing results. By using water in the sieving process, any clay, silt, or dust that may adhere to the surface of the aggregate is removed, allowing for a more accurate assessment of the coarse aggregate's quality.

The other options do not appropriately address the need to separate the large coarse aggregate particles effectively. Dry screening through a fine sieve may not provide the necessary separation for larger aggregates, while visual inspection of aggregate alone lacks the precision needed for concrete testing. Mixing with finer aggregates does not resolve the issue of properly preparing the concrete for testing and may introduce variability that could affect the results. Therefore, wet sieving is the correct procedure to ensure reliable and valid test outcomes for concrete containing larger coarse aggregates.