With the increasing environmental pressure caused by waste plastic (WP), incorporating recycled plastics into asphalt concrete has become a promising strategy for sustainable pavement construction. In this study, waste polyethylene terephthalate (PET) was utilized to replace mineral aggregates through a dry process, and the effects of particle size and replacement level on the mechanical performance of asphalt concrete were systematically evaluated. High-temperature deformation resistance was assessed using wheel-tracking tests, followed by dynamic modulus measurements to examine the viscoelastic behavior and structural stiffness. Low-temperature cracking resistance was studied through fracture toughness and fracture energy tests, and fatigue performance was investigated using four-point bending fatigue tests. In addition, SCB (semi-circular bending) crack propagation observations and crack length analysis were conducted to clarify the influence of PET on crack development behavior. The research results indicated that coarse PET particles effectively participate in the load-bearing skeleton, significantly enhancing rutting resistance and high-frequency stiffness, whereas fine PET particles exhibit superior dispersion and void-filling capability, thereby improving low-temperature cracking resistance. An optimal PET replacement level was identified, as excessive substitution disrupts the mineral skeleton and leads to performance deterioration. PET increased crack tortuosity and final crack length, with a modest rise for fine PET but a larger, replacement-dependent increase for coarse PET due to stronger skeleton interference. Overall, moderate PET replacement provides balanced improvements in high-temperature stability, low-temperature cracking resistance, and fatigue durability, demonstrating the potential of waste PET as an effective aggregate substitute for sustainable asphalt pavement applications.
Jia et al. (Thu,) studied this question.