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 enhance the low-temperature fatigue performance and structural stability of rubber-modified asphalt (RA), activated waste tire rubber powder (ARP) was developed through microwave desulfurization, and activated waste tire rubber composite-modified asphalt (ARA) was prepared. The conventional properties, rheological performance, and microstructure of ARA were comprehensively tested. The results indicate that ARA significantly improves the high temperature, low temperature, and stability compared with RA. The high-temperature resistance to permanent deformation and the elastic recovery ability of ARA were found to be significantly improved. The comprehensive performances of ARA show improvement compared to styrene-butadiene-styrene-modified asphalt as the resin content increases and the ARP decreases. Nuclear magnetic resonance and Fourier transformation infrared spectroscopy analysis indicate that the reduction in internal cross-linking structures and the breaking of chemical bonds in ARP enhance its compatibility with the base asphalt. Furthermore, the formation of a three-dimensional network structure through reactive blending is fundamental to the overall performance improvement of ARA. The performance benefits of ARA in asphalt mixtures are comprehensively confirmed, providing theoretical guidance for the efficient use of waste tire rubber powder in road engineering.

Due to the poor comprehensive performance of traditional rubber powder-modified asphalt (RA) and issues like easy segregation in rubber powder/Styrene–Butadiene–Styrene (SBS) composite-modified asphalt, the application of RA in high-grade highways is limited. This study combined SEBS (Styrene–Ethylene–Butylene–Styrene) and SBS to form SEBS/SBS (SE-S) and investigated the effect of the SE-S system on asphalt performance. The activated desulfurized rubber powder (ARP) was prepared via mechanical thermal oxidation and used to produce ARP/SE-S composite-modified asphalt (ASSA) combined with SE-S. The performance and modification mechanism of ASSA were evaluated through conventional, rheological, and microstructural tests. The results showed that SEBS improved storage stability more effectively than SBS. With SEBS:SBS = 0.4:0.6 and a SE-S content of 2–4%, the modified asphalt exhibited better overall performance. The synergy of ARP and SE-S enhances both low-temperature crack resistance and high-temperature deformation resistance, endowing ASSA with excellent viscoelastic rheological properties. The modification mechanism of ASSA was primarily physical and the changes in chemical bonds were mainly caused by decrosslinking of the rubber powder during ARP preparation. SE-S and ARP fully swelled and crosslinked in the asphalt, exhibiting excellent compatibility and endowing the ASSA with superior stability and performance.