Compaction for wearing and binder course must be completed before the temperature of the mix falls below what temperature?

In asphalt paving, compaction is a critical process that must be executed while the asphalt mix is still hot to ensure proper density and performance. The temperature at which compaction is required to be completed plays a significant role in the effectiveness of the mix and the longevity of the pavement.

Completing compaction before the mix falls below 90°C is essential for several reasons. At higher temperatures, the asphalt binder is more fluid, which allows for better coating of the aggregates and the ability to achieve proper interlock between the particles. This improves the overall strength and durability of the asphalt layer.

If compaction occurs below this threshold, the viscosity of the asphalt binder increases, making it challenging to achieve adequate density and potentially leading to voids in the mix. Voids can compromise the durability and load-bearing capacity of the pavement, resulting in premature failures or other issues down the line.

This 90°C benchmark is established based on both empirical evidence from field studies and laboratory tests that assess the performance of asphalt under various temperature conditions. It strikes a balance between ensuring optimal workability of the mix and preventing insufficient compaction that could compromise the pavement's performance over time.