Eco-friendly asphalt mixtures: examining the performance of PE pyrolytic wax-modified bitumen for road construction

Abstract

This study investigates the potential of plastic waste use in road construction as a means for recycling and environmental impact reduction. The impact of polyethylene (PE) pyrolytic wax-modified bitumen on asphalt properties was examined in this study. Asphalt samples were formulated with virgin bitumen, 7% PE wax-modified bitumen, 5% polypropylene (PP), and a combination of both. Optimal bitumen content was established as 6.05% for virgin bitumen, 6.6% for 5% PP, 6.0% for 7% wax, and 6.15% for the blend. Despite the 7% wax sample's lower indirect tensile strength (ITS) of 1.76 MPa, compared to 2.11 MPa for the 5% PP sample, it did not significantly differ from the sample with virgin bitumen. Similar findings emerged for ITS at cold temperatures (3.46 MPa for 7% wax vs. 3.399 MPa for 5% PP) and high temperatures (0.697 MPa for 7% wax vs. 0.861 MPa for 5% PP). The PE wax-modified bitumen samples satisfied dense-graded specifications, displaying consistent resistance to common deterioration mechanisms. Our findings propose that PE wax-modified bitumen is a sustainable approach to plastic waste management, capable of reducing bitumen and energy demand while preserving pavement lifespan. Furthermore, PE wax allows a 7.83% reduction in virgin bitumen content, a decrease in mixing and compaction temperatures by 14 °C and supports higher recycling rates compared to asphalt mixtures modified with untreated plastic waste.