Asphalt pavements are prone to various distresses under complex environmental influences during service, which significantly affects their fatigue life. This study conducted complex environmental simulation tests, including pressure aging, ultraviolet (UV) aging, and coupling effects with salt solutions at different concentrations. A dynamic shear rheometer (DSR) was employed to perform frequency sweep tests, linear amplitude sweep (LAS) tests, and fatigue–healing–fatigue tests. The fatigue self-healing properties of fast-melting SBS (SBS-T)-modified asphalt were evaluated based on the viscoelastic continuous damage theory. The results indicate that coupled aging effects significantly increase the viscoelastic characteristic parameters of SBS-T-modified asphalt, with more elastic components transforming into viscous components. Compared to other aging effects, the coupled pressure-UV-salt solution condition induces the most severe degradation in the fatigue durability of SBS-T-modified asphalt. Simultaneously, the self-healing capability of aged asphalt is also reduced. Specifically, with increasing strain, more complex aging conditions lead to the faster deterioration of asphalt fatigue life and lower self-healing capacity. While asphalt demonstrates measurable fatigue life restoration through self-healing, the synergistic coupling of salt solution exposure and multi-factor aging significantly compromises both the absolute fatigue resistance and the relative recovery efficiency.

Increasing the frequency and duration of extreme heat events significantly compromises asphalt pavement performance, particularly in critical urban infrastructure such as heavily trafficked pavements, BRT lanes, and intersections subjected to slow-moving heavy traffic under extreme temperatures. This study systematically investigates rutting formation mechanisms through integrated theoretical and numerical approaches, addressing significant knowledge gaps regarding rutting evolution under coupled extreme-temperature (70 °C), heavy-load (100 kN–225 kN), and braking conditions (1 m/s²–7 m/s²). A three-dimensional thermo-mechanical finite element model integrating solar radiation heat transfer with the Bailey–Norton creep law was developed to quantify synergistic effects of axle loads, travel speeds, and braking accelerations. Results demonstrate that when the pavement surface temperature rises from 34 °C to 70 °C, the rutting depth is increased by 4.83 times. When the axle load is increased from 100 kN to 225 kN, the rutting of conventional asphalt pavements under 70 °C is increased by 56.4%. Rutting is exacerbated by braking acceleration; due to prolonged loading duration under low acceleration, the rutting depth is increased by 30–40% compared with that under emergency braking. These findings establish theoretical foundations for optimizing pavement design and material selection in slow-moving heavy-load environments, delivering significant engineering value for transportation infrastructure.