Aging evolution and sustainability implications of crumb rubberized asphalt binder: A state-of-the-art

Crumb rubberized asphalt binder achieves value-added recycling of waste scrap tires, as well as enhancement of mechanical properties and aging resistance of asphalt pavements. This paper provides a systematic literature review of the aging evolution and sustainability implications of crumb rubberized asphalt binder based on peer reviewed publications during 1993-2022. The analysis of the literature shows that aging methods, chemicalmicrostructural characterization, rheological-mechanical properties, and environmental benefits are the main research directions in studying aging of crumb rubberized asphalt binder. Furthermore, recent investigations mainly concentrate on the thermal aging behavior of crumb rubberized asphalt binder, while ultraviolet-induced aging and weathering aging lack attention. Rubber degradation is a characteristic manifestation of crumb rubberized asphalt binder during aging that can be characterized by chemical investigations. Aging-induced cracks are mitigated by rubber particles shown by microstructural observations. Rheological-mechanical investigations show different evolutions in high-temperature properties of crumb rubberized asphalt binder after aging, but a superior low-temperature cracking resistance as compared to base asphalt as well as styrene-butadiene-styrene modified asphalt has been observed. The inconsistent findings in the fatigue properties of aged crumb rubberized asphalt binder are compared and attributed to the selection of evaluation indicators. Life cycle assessment shows that depending on the local waste management policy, significant environmental benefits of crumb rubberized asphalt binder in terms of reduced energy consumption and global warming potential are possible.