Preparation of eco-friendly organic active zeolite and its impact on rejuvenated SBS modified asphalt and mixture: From pavement performance to fume suppression

To promote the green and sustainable development of asphalt recycling technology, this study employed hexamethylene diisocyanate (HDI) to organically modify zeolite, producing an eco-friendly reactive zeolite bearing active isocyanate groups (AIG-Z). The chemical structure, crystalline configuration, particle size distribution, pore characteristics, and micromorphology of the obtained material were systematically characterized. Subsequently, the aged SBS modified asphalt (PmA) was rejuvenated using a composite of AIG-Z and cardanol. A comprehensive evaluation was conducted on the physical properties, rheological behavior, aging resistance, and fume emission characteristics of the rejuvenated PmA. Additionally, the road performance of the corresponding asphalt mixture was analyzed. The results indicated that AIG-Z was successfully prepared, with HDI achieving surface grafting without altering its crystal structure. Moreover, AIG-Z exhibited improved dispersibility and a reduction in particle size. Both unmodified zeolite and AIG-Z were able to enhance the overall performance of the rejuvenated PmA and its mixture, with AIG-Z showing the most pronounced improvement. Compared to unmodified zeolite, AIG-Z decreased the storage segregation of rejuvenated PmA by 76.47 % while also reducing the emissions of VOCs, H 2 S, SO 2 , and NO x by 39.75 %, 45.45 %, 48.89 %, and 31.36 %, respectively. The high-temperature stability of the rejuvenated PmA was improved by the AIG-Z, with the critical rutting temperature increasing by 2.5°C, and the R̄ 0.1 and R̄ 3.2 values rising by 14.12 % and 17.98 %, correspondingly. Concurrently, AIG-Z also significantly enhanced the aging resistance of the rejuvenated PmA. In terms of mixture performance, AIG-Z could further increase the dynamic stability of the recycled mixture by 1563 times/mm, enhance the maximum flexural tensile strain by 658 με, and improve the freeze-thaw splitting strength ratio by 7.97 %.