ACI Concrete Field Testing Technician - Grade I Practice Exam

What must be done to a concrete sample containing aggregate larger than permitted before conducting a test?

1. Sent to a lab for analysis

2. Dry sieved

3. Wet sieved

4. Crushed into finer aggregates

The correct answer is: Wet sieved

To ensure accurate testing results, when a concrete sample contains aggregate larger than the specified limits, wet sieving is the appropriate method to prepare the sample before conducting tests. Wet sieving involves passing the sample through a series of sieves with water, which helps to separate the larger aggregates from the smaller particles effectively and minimizes the chance of clumping. This method is particularly useful as it also helps to wash off any excess cement paste that may adhere to the surface of the aggregates, allowing for a more precise assessment of the concrete's properties. In contrast, other methods such as dry sieving could lead to issues where dust or fine particles may not be adequately separated due to the lack of water, and sending the sample to a lab could delay results without addressing the immediate need for testing preparation. Crushing the aggregates into finer pieces alters the sample's characteristics, which is not suitable for the purpose of accurate field testing of the original concrete mix. Thus, wet sieving is the correct and best practice for handling oversized aggregates in field tests.