High-viscosity modified asphalt, as a key material ensuring the durability of permeable pavement structures, is prone to aging during long-term service, severely impacting pavement performance. This study selected three typical high-viscosity modified asphalts: SBS (Styrene-Butadiene-Styrene) type (H-type), composite rubber type (L-type), and TPS high-viscosity modified asphalt (T-type). The multi-stage aging process was simulated using Thin Film Oven Test (TFOT) and Pressure Aging Vessel (PAV) methods. Microscopic characterization techniques, including Fluorescence Microscopy (FM), Fourier Transform Infrared Spectroscopy (FTIR), Gel Permeation Chromatography (GPC), and Thin-Layer Chromatography with Flame Ionization Detection (TLC-FID), were employed to systematically reveal their aging mechanisms. The results indicate that all three types of high-viscosity asphalt follow a typical aging path characterized by "volatilization of light components, accumulation of large molecules, and colloidal instability." The progression and sensitivity of aging primarily depend on the type of modifier. H-type asphalt exhibits a two-stage aging pattern: it remains relatively stable at early stages but undergoes rapid SBS-segment degradation at PAV 20 h, evidenced by a 181 % increase in carbonyl groups and a 67.9 % rise in the large-molecule fraction, indicating accelerated aging. L-type asphalt demonstrates the most severe aging reactions. Due to the abundant unsaturated bonds and carbonyl groups present in the crumb rubber modifier, its oxidation reaction shows a linear progression. After 30 h of PAV aging, its colloidal instability index exceeds 0.7, signifying that the system approaches complete instability. T-type asphalt benefits from its cross-linked network structure, which forms an effective spatial barrier significantly inhibiting oxygen diffusion and structural damage. After PAV 40 h, its loss rate of small molecules is only 15 %, achieving a relatively ordered degradation process. This study clarifies the differences in structural evolution and aging mechanisms among different types of high-viscosity modifiers, providing a theoretical basis for the material design and selection of permeable pavements.
