In this study, four types of anti-ultraviolet aging agents—layered double hydroxides (LDHs), organic montmorillonite (OMMT), titanium dioxide (TiO₂), and ultraviolet absorber (UV326)—were employed to modify asphalt. The modified asphalt samples underwent Rolling Thin Film Oven Test (RTFOT) and xenon-lamp aging treatments, and we examined the evolution of their physical properties, rheological performance, and chemical composition. A principal component analysis (PCA) model built on representativeness, discriminative power, and non-redundancy reduced the multidimensional data to two principal components, which together captured 87.540% of the total variance. The dynamic principal component trajectories, plotted from the reduced-dimension data for the unaged–short-term-aged–xenon-lamp-aged process, revealed that anti-aging agents sharing the same protection mechanism led to comparable rates of high- and low-temperature performance deterioration during xenon-lamp aging, whereas agents with different mechanisms resulted in distinctly different patterns of performance deterioration. In the critical xenon-lamp aging stage, the neat asphalt exhibited a trajectory vector change of ΔPC1 = 0.92 and ΔPC2 = 1.25, corresponding to an angle of 54°, reflecting a low-temperature degradation. By contrast, the physical shielding agents LDHs and OMMT produced much steeper trajectories with angles of approximately −80°, where ΔPC2 values rose to as high as 3.67 and 2.19 respectively despite modest reductions in overall aging. The reflective agent TiO₂ showed a more moderate angle of 84°, with ΔPC1 and ΔPC2 values of 0.16 and 1.45, indicating a slight retardation of high-temperature performance loss. Notably, the UV absorber UV326 maintained the same trajectory angle of 56° as the neat asphalt but with reduced magnitudes of ΔPC1 = 0.63 and ΔPC2 = 0.94, suggesting a balanced delay in aging without altering its relative progression. This study proposes a novel analytical framework for mechanism-based clustering analysis and the precise selection of anti-aging agents for asphalt.

To address the low resource-recovery efficiency of waste polyethylene terephthalate (PET) and the shortage of high-performance eco-friendly asphalt modifiers, PET-derived functional additives were fabricated in this work via zinc-acetate-catalyzed alcoholysis of waste PET followed by repolymerization of the obtained degradation fragments. Owing to the diverse origins of waste PET feedstock, noticeable fluctuations in molecular-weight parameters are commonly encountered. Nevertheless, waste PET can be effectively depolymerized into relatively low-molecular-weight derivatives under the proposed catalytic alcoholysis conditions. This study systematically investigated the effects of different PET degradation pathways on the molecular architecture, molecular-weight distribution, and thermal stability of as-prepared PET-derived asphalt additives. It further uncovers the intrinsic structure–performance relationships between molecular characteristics and critical asphalt properties, including rheological behavior, interfacial adhesion, high-temperature rutting resistance, and low-temperature elastic recovery. Homogeneous alcoholysis conducted at 220 °C enables efficient depolymerization of waste PET to yield derivatives with tailorable molecular weights. The resultant amphiphilic alcoholysis products can reduce asphalt viscosity and ameliorate water stability, rendering them promising warm-mix anti-stripping additives. By contrast, repolymerized PET derivatives are capable of constructing cross-linked networks within asphalt matrix, which substantially boost the high-temperature modulus and fatigue resistance of modified asphalt. Distinct from conventional physical blending approaches that are plagued by inferior interfacial compatibility and marginal performance improvement, this chemical modification strategy affords PET-based additives with tunable functions for different engineering scenarios. These findings provide technical support for high-value recycling of waste PET and the development of sustainable low-carbon asphalt materials.