Which factor is critical to achieving proper compaction of asphalt layers?

The timing of the compaction process is indeed critical for achieving proper compaction of asphalt layers. When asphalt is laid down, it is essential to compact it while the temperature is optimal. If compaction occurs too early or too late, the mix may not be malleable enough to form a proper bond between the asphalt particles, leading to inadequate compaction. Proper timing ensures that the asphalt remains hot enough to achieve the necessary workability, allowing for effective densification and minimizing air voids.

Temperature plays a significant role in the effectiveness of the roller and the overall performance of the pavement. Once the asphalt cools below a certain point, further compaction can lead to cracking or other defects, which may compromise the integrity of the pavement over time. Thus, understanding and executing the compaction process at the right moment is essential for the long-term performance of asphalt layers.

While factors like water content, thickness, and type of aggregate can influence the overall quality and durability of the pavement, they are secondary to the immediate need for precise timing during the compaction process to achieve optimal results.