Rheological and micro characteristics of asphalt containing different nanocomposite ratios of CeO2/MMT during thermal-oxidative and ultraviolet aging

To enhance the long-term service performance of asphalt pavements under aging conditions, this study investigated the effects of nano-CeO 2 /montmorillonite (MMT) composites at different ratios (CM0.2, CM0.5, CM1.0) on the rheological properties and microstructural characteristics of asphalt subjected to various aging protocols. By employing dynamic shear rheological (DSR), gel permeation chromatography (GPC), and atomic force microscopy (AFM) tests, the performance changes of nano-CeO 2 /MMT composite-modified asphalt (CMMA) under thermal-oxidative aging (rolling thin film oven (RTFOT, 163 ℃, 85 min), pressure aging vessel (PAV, 100 ℃, 2.1 MPa, 20 h)) and ultraviolet (UV, 60 ℃, 6 d) aging was systematically analyzed. The CM0.5 composite demonstrated superior anti-aging efficacy: the UV absorption capability of CeO 2 synergized with the lamellar physical barrier effect of MMT to effectively inhibit oxidative cross-linking of asphalt macromolecules. Compared to the base asphalt, CMMA with CM0.5 (CMMA0.5) exhibited significantly enhanced rheological properties, including higher complex modulus and rutting factor, along with outstanding high-temperature deformation resistance. Following UV aging, CMMA0.5 showed a 44 % reduction in the complex modulus aging index (CMAI) at 60 °C compared to the base asphalt. AFM results further confirmed the stability of the "bee structure" in CMMA0.5 before and after UV aging, with minimal variations in surface roughness, modulus, and adhesion force. The nano-composite modification strategy proposed here achieves functional complementarity between CeO 2 ’s UV absorption and MMT’s physical barrier, offering an innovative solution for improving asphalt pavement durability.