Evaluation of HDPE plastic waste as a coarse aggregate substitute in Hot Rolled Sheet-Wearing Course asphalt mixtures

Abstract Plastic-based goods are commonly used in daily life, but their waste poses significant environmental challenges due to its durability. This study investigates the use of recycled plastic as an artificial coarse aggregate in asphalt mixtures, specifically assessing the effects of High-Density Polyethylene (HDPE) on Hot Rolled Sheet Wearing Course (HRS-WC) mixtures. The objectives are to evaluate the physical properties of the artificial coarse aggregates, identify the optimal asphalt content and Marshall characteristics, and determine the maximum feasible substitution level for these aggregates. A test specimen (briquette) was produced for the Marshall test to assess the mixture properties. Our findings indicate that the maximum allowable substitution of HDPE plastic in HRS-WC mixtures is 42%. With an optimal asphalt content of 7.30%, HDPE substitution levels of 30%, 35%, 40%, 45%, and 50% yielded the highest stability at 45% (1176.696 kg), the highest VMA at 30% (21.250%), and the highest VIM within specifications at 30% (4.998%). The highest VFB value was observed at 45% (88.767%), while the highest Marshall Quotient was at 30% (364.527 kg/mm). The study recommends a maximum HDPE plastic waste substitution level of 40%, highlighting the potential for using HDPE plastic waste in asphalt mixtures to promote more sustainable construction practices.