What is the primary use of a soft brass wire brush in aggregate testing?

The primary use of a soft brass wire brush in aggregate testing is to clean aggregates without damaging them. This is crucial because during the testing process, particularly in gradation and quality assessments, any contaminants or debris on the surface of the aggregates can significantly affect the results.

Using a soft brass wire brush allows technicians to remove any adhering fine particles, dust, or other impurities while minimizing the risk of scratching or altering the aggregate's surface. This ensures that the aggregates' natural properties are preserved, leading to more accurate testing results. The brush’s softness is important; it is specifically designed to clean effectively without introducing any additional damage, which would skew test outcomes.

In contrast, options such as polishing aggregates or measuring aggregate size are not the intended functions of the brass wire brush. Mixing aggregates also falls outside the scope of what this tool is designed to do, as it is not meant for combining materials but rather for preparing them for further evaluation.