Enhancing the service life of crumb rubber modified asphalt under intense ultraviolet radiation: Assembled with hydrotalcite by controlling temperature and pretreatment process

Waste crumb rubber (CR) has been demonstrated to enhance the rheological performances of modified asphalt. However, crumb rubber modified asphalt (CRMA) is susceptible to ultraviolet (UV) degradation under intense UV radiation, which shortens its service life and leads to increased maintenance costs. To address this limitation, layered double hydroxides (LDHs) with superior UV-shielding were combined with CR particles via screw extrusion technology to fabricate an assembled composite modifier in this study. Meanwhile, the screw extrusion temperature and CR pretreatment process were precisely controlled to stabilize the composite structure and enhance the service performances. To evaluate the effectiveness of CR pretreatment process, multi-scale characterizations were conducted to analyze the modifier’s morphology, functional groups, interfacial interaction with asphalt matrix and service properties of corresponding modified asphalts. Grey relational analysis was simultaneously employed to establish the correlation between multi-scale parameters. The results indicated that pre-swelling CR with waste cooking oil enhanced the thermal storage stability and low-temperature UV aging resistance of LDHs-CR modified asphalt by 55.3% and 87.5%, respectively. This enhancement is attributed to the strengthened interfacial interaction between the composite modifier and asphalt matrix. Additionally, microwave activation process improved the UV aging resistance index by up to 62.7%, which is driven by surface structural evolution of composite modifier. By comparison in the variations of elevated extrusion temperatures from 150℃ to 250℃, it can be concluded that the CR pretreatment methods deliver equivalent effects in key service performances, providing a robust theoretical basis for preparing high-performance, low-cost and environmentally friendly LDHs-CR modified asphalt.