Recycled Plastic Waste Asphalt Concrete via Mineral Aggregate Substitution and Binder Modification

Abstract

Plastic waste (PW) has long been identified among the direct and indirect primary sources of environmental pollution. Currently, global PW generation is more than 300 million tons annually and is increasing at a rate of 4% per year. Recycling has been recognized as a key technique, among others, for addressing the environmental hazards associated with PW. Prior studies on the modification of asphalt concrete (AC) using PW have been mostly about asphalt binder modification or mineral aggregate substitution for better AC properties. Several studies have focused on stone mastic asphalt concrete (SMA) or isolating recycled polyethylene terephthalate (RPET) as an aggregate substitute. In this study, a combined form of recycled plastic waste (RPW) was used as a mineral aggregate supplement in a dense-graded hot mix asphalt (HMA) AC made with RPW-modified asphalt binder. The term hybrid RPW-AC is used to refer to the HMA AC in this study. The viscoelastic performance of ACs containing combined RPW aggregates were compared with those containing RPET-only aggregates. Dynamic modulus (|E*|) tests, flow number (FN) tests, and rutting resistance tests using an asphalt pavement analyzer (APA) were utilized to evaluate the performance of the hybrid RPW asphalt concrete mixes and were compared to fresh, RPET, and crumb rubber AC. The results showed that combined RPW as an aggregate supplement has advantages over the use of RPET-only aggregates. The hybrid RPW-AC showed superior performance compared to the reference mixtures.