Comparative life cycle assessment of waste polyethylene utilization for polymer-modified asphalt and pyrolysis oil production

Due to the expanding demand for plastics, waste polyethylene (PE) management has become a global challenge. This study focuses on two pivotal techniques applicable for waste PE utilization as life cycle scenarios, that is, (1) polymer-modified asphalt production and (2) pyrolysis oil production. The study applies standard life cycle assessment (LCA) methodology to evaluate life cycle material flows, energy flows and environmental impacts for the two scenarios processing 1 tonne of waste PE in municipal solid wastes. Utilization of waste PEs at a ratio of 250 tonnes of polymer-modified asphalt/tonne of waste saves 8.19% of energy compared to the normal asphalt preparation process. At the same time, pyrolysis yields a net energy ratio of 1.07. Moreover, results reveal that utilizing waste PEs for polymer-modified asphalt production is more environmentally benign compared to pyrolysis. These implications have significant variations mainly due to yield parameters. Further interpretation of LCA results and sensitivity parameters are analysed to support future implementations.