Small transverse cracks visible under the roller may indicate what issue?

Small transverse cracks that appear under the roller during the hot mix asphalt (HMA) process often signal potential over-compaction. This phenomenon occurs when the asphalt mixture is subjected to excessive pressure, leading to an inability of the material to accommodate the stresses imposed by the roller.

When asphalt is compacted beyond its optimal density, it can result in internal structural issues, manifesting as transverse cracks. This is particularly critical in the context of maintaining the integrity and longevity of the pavement. Recognizing these cracks as a sign of over-compaction is essential for inspectors, as it not only affects the immediate appearance and performance of the surface but could also imply long-term durability concerns.

In contrast, the other options address different aspects that do not directly correlate with the appearance of small transverse cracks under the roller. Cold weather effects typically lead to other forms of distress such as thermal cracking, while proper roller operation would generally not induce such cracks. Insufficient asphalt application relates to thickness and coverage issues but not directly to the compacting effects that would produce these cracks. Understanding these distinctions helps inspectors make accurate assessments during pavement construction or rehabilitation.