How do "excessive fines" in the aggregate impact asphalt pavements?

Excessive fines in the aggregate negatively impact asphalt pavements primarily by leading to reduced durability. Fines refer to the very small particles in the aggregate mix, and when there are excessive amounts, they fill the voids between larger stones. This overabundance can create a dense mix that inhibits the proper binding and compaction of the asphalt. As a result, the formation of air voids is compromised, which is essential for allowing the pavement to withstand environmental stresses.

Moreover, a high quantity of fines can affect the mix's resistance to deformation, cracking, and fatigue, resulting in premature surface distress and reduced lifespan of the pavement. A well-balanced aggregate mix, with the appropriate gradation of particle sizes, ensures that the asphalt is strong enough to withstand loads, resist moisture infiltration, and minimize the development of cracks over time. This is why maintaining an optimal level of fines is crucial for the performance and longevity of asphalt pavements.