Recycled plastics as synthetic coarse and fine asphalt aggregate

This study investigates the performance of asphalt concrete containing recycled plastics as synthetic aggregates in the dry mixing process. Two types of recycled plastics were used, namely, acrylonitrile butadiene styrene (RABS) and Polyethylene Terephthalate (RPET), based on the high-temperature properties of the plastics that make them suitable to be treated as synthetic aggregates (i.e. do not melt during the asphalt mixing phase). The proportions of recycled plastics were chosen at 0.5%, 1%, 2% and 4% of the mix mass. The laboratory testing programme includes the evaluation of compactability properties, moisture resistance, cracking resistance via IDEAL-CT test, fatigue resistance via four-point bending beam test and rutting resistance via Hamburg wheel tracking (wet) test. It was found that the inclusion of recycled plastics did affect the compactability of the mixes depending on their relative size and shape. On the other hand, the inclusion of recycled plastics did not significantly vary the moisture resistance of asphalt mixes. The cracking and rutting behaviour of asphalt mixes that incorporated recycled plastics were also modified and some benefits were observed depending on the plastic content and size.