How do varying levels of compaction influence the long-term performance and durability of pavement patches?

Compaction is the process of densifying asphalt or concrete mixtures by reducing air voids. Varying levels of compaction significantly influence the long-term performance and durability of pavement patches. Inadequate compaction results in a patch with a higher air void content, making it more susceptible to several distresses. Water infiltration is a major concern as higher air voids allow water to penetrate the patch, weakening the bond between the asphalt and aggregate (stripping) or causing freeze-thaw damage in concrete. Reduced strength and stability occur due to the higher air void content reduces the strength and stability of the patch, making it more susceptible to rutting and deformation under traffic loads. Accelerated oxidation, meaning the asphalt binder oxidizes more rapidly due to the increased surface area exposed to air, leading to embrittlement and cracking. Raveling, the loss of aggregate from the patch surface, occurs because the asphalt binder is not adequately supporting the aggregate particles. On the other hand, excessive compaction can also be detrimental. Over-compaction can crush aggregate particles, reducing the strength and durability of the patch. It can also lead to a reduction in permeability, which can trap moisture within the patch. Proper compaction, achieving the target density specified in the mix design, is essential for ensuring the long-term performance and durability of pavement patches. This requires using appropriate compaction equipment and techniques, controlling the moisture content of the mixture, and monitoring the compaction process. Density gauges or core samples are used to verify that the desired compaction level has been achieved.