Prospective LCA of valorizing end-of-life tires in asphalt mixtures with emerging pretreatment technologies of crumb rubber

Despite numerous research studies devoted to quantify the environmental impacts associated with the valorization of crumb rubber (CR) derived from end-of-life tires (ELTs) in asphalt pavement construction, the number of life cycle assessment (LCA) studies scrutinizing the implementation of emerging CR pretreatment technologies remains scarce. Therefore, this study aims to conduct a prospective LCA study on the ELTs valorization in asphalt mixtures, with a focus on the application of two emerging supercritical pretreatment technologies of CR, namely the supercritical swelling pretreatment and the supercritical de-crosslinking pretreatment. The findings show that the supercritical swelling pretreated crumb rubber modified asphalt (CRMA) materials with a 40 % dosage obtained the lowest environmental impact score in the majority of the impact categories. Further, the supercritical pretreatment process of CR played a critical role in driving the environmental impacts of pretreated CRMA materials. Desipite this, the environmental impacts of supercritical pretreated CRMA materials exhibited relatively higher uncertainty. Finally, the analysis of scaled-up scenarios highlights the effectiveness of reusing carbon dioxide as reaction medium and reducing the use of dry ice and chemical reagent in minimizing the overall environmental impacts.