Environmental impact of pavements formulated with bitumen modified with PE pyrolytic wax: A comparative life cycle assessment study

Abstract

This study aimed to evaluate the environmental impacts of various bitumen modifiers on asphalt production, given its significant contribution to greenhouse gas emissions, waste generation, and the depletion of non-renewable resources. Four bitumen modifiers were compared, namely, recycled polyethylene (PE) pyrolytic wax, ethylene-vinyl acetate (EVA), recycled polypropylene (PP), and a combination of PE pyrolytic wax and PP, using the life cycle assessment method with one km of road as the functional unit. Results showed that the use of asphalt mixtures formulated with bitumen modified with PE pyrolytic wax had the lowest environmental impact, with a 5.9% decrease compared to traditional pavement. This reduction was attributed to the generation of environmental credits from pyrolysis and a decrease in the amount of virgin bitumen needed for asphalt mixture formulation. Conversely, binders modified with EVA and recycled PP had the highest environmental impact due to high maintenance requirements and environmental impacts in their corresponding additives, with 12% and 5% more impact than traditional pavement, respectively. The study further noted that overall environmental performance was highly sensitive to the amount of bitumen required and the yield of wax produced during pyrolysis, indicating the importance of carefully selecting bitumen modifiers. Based on the findings, the study recommends the use of asphalt mixtures formulated with bitumen modified with PE pyrolytic wax due to their favourable environmental performance.