What does the term 'cleanliness' refer to in aggregate quality?

The term 'cleanliness' in aggregate quality specifically refers to the absence of harmful substances such as clay, silt, and dust. These materials can negatively impact the performance of the aggregate in construction applications. For instance, excessive clay or dust can inhibit the bonding of cement to the aggregate, leading to weakened concrete structures. Clean, well-graded aggregates facilitate better compaction and improve the strength and durability of the resulting concrete or asphalt mixes.

Other factors, like the consistency of color, the size of particles, or the grading may influence aggregate quality but do not directly relate to the concept of cleanliness. Cleanliness is strictly concerned with ensuring that the aggregate is free from contaminants that could compromise its structural integrity and performance. Thus, focusing on the removal of unwanted materials is crucial for achieving high-quality aggregate.