The use of recycled polyester fiber (Re-PET) partially addresses the scarcity of non-renewable polyester (PET), but its thermal resistance in asphalt mixtures is relatively low. To enhance the reutilization and thermal resistance of Re-PET, it was modified through in situ growth grafting with tetrahedral nanoSiO₂. A novel nanoSiO₂ hybrid material (SiO₂/Re-PET) was successfully prepared, and the effects of the surface modification on the morphology and thermal resistance of the Re-PET were investigated with the examination of its mechanism of modification. The results demonstrated an increase in the surface roughness and specific surface area of SiO₂/Re-PET, as well as a higher melting point and structural stability compared to Re-PET. Subsequently, Re-PET and SiO₂/Re-PET asphalt mastics under a filler–asphalt ratio of 1.0 were prepared, and their classical and rheological properties were investigated and compared. The results indicated an increase in the softening point and shear strength of SiO₂/Re-PET asphalt mastic, as well as a significant improvement in its high-temperature performance. Furthermore, subsequent pavement performance tests revealed a significant improvement in the performance of SiO₂/Re-PET asphalt mixtures compared to Re-PET asphalt mixtures. Consequently, the findings of this research promote the recycling of Re-PET, ultimately advocating for the sustainability of pavement construction.

To develop a cost-effective, high-viscosity asphalt for porous asphalt pavement, we utilized SBS, tackifier, and solubilizer as the main raw materials, identified the optimal composition through an orthogonal experiment of three factors and three levels, and prepared a low-cost high-viscosity asphalt. We compared its conventional and rheological properties against those of rubber asphalt, SBS modified asphalt, and matrix asphalt, employing fluorescence microscopy and Fourier transform infrared spectroscopy for microstructural analysis. The results indicate that the optimal formula composition for high-viscosity asphalt was 4–5% styrene-butadiene-styrene (SBS) + 1–2% tackifier +0–3% solubilizer +0.15% stabilizer. The components evenly dispersed and the performances were enhanced with chemical and physical modification. Compared with SBS modified asphalt, rubber asphalt, and matrix asphalt, the softening point, 5 °C ductility, and 60 °C dynamic viscosity of high-viscosity asphalt were significantly improved, while the 175 °C Brookfield viscosity was equivalent to SBS modified asphalt. In particular, the 60 °C dynamic viscosity reaches 383,180 Pa·s. Rheological tests indicate that the high- and low-temperature grade of high-viscosity asphalt reaches 88–18 °C, and that high-viscosity asphalt has the best high-temperature resistance to permanent deformation and low-temperature resistance to cracking. It can save about 30% cost compared to commercially available high-viscosity asphalt, which is conducive to the promotion and application of porous asphalt pavement.