基于氢化还原与端基钝化的老化沥青化学修复机制与性能评价

针对废旧沥青因性能劣化引起的再生沥青混合料路用性能不佳的问题，选用氢化还原剂三乙氧基硅烷将老化沥青中的强极性羰基和亚砜基还原成羟基，生成极性较低的酯或者醚；再通过端基钝化剂异氰酸酯与羟基进行酯化反应，实现端基钝化。通过测试老化沥青各修复阶段的微观化学结构与极性变化，研究其修复机理；进而以基质沥青为参比，分析测试老化沥青性能修复前后的动力粘度和低温性能，评价氢化还原与端基钝化对老化沥青的化学修复效果。结果表明，氢化还原与端基钝化使老化沥青的化学结构发生了本质的变化，三乙氧基硅烷可将老化沥青中羰基和亚砜基还原成羟基，异氰酸酯可将羟基酯化成酯；经氢化还原与端基钝化之后，老化沥青的极性显著减弱，分子间作用力和粘度明显降低，低温变形能力得以显著改善，且老化沥青的低温性能与官能团指数之间具有良好的相关性。

Mechanism and properties evaluation of chemical remediation of aged asphalt based on hydrogenation reduction and end group deactivation

Addressing the issue of poor pavement performance in reclaimed asphalt mixture caused by the deterioration of aged asphalt properties, this study explores the use of triethoxy silane to convert strong polar carbonyl and sulfoxide groups in aged asphalt into hydroxyl groups. Simultaneously, low polarity ester or ether are generated. Subsequently, the hydroxyl groups are esterified with the end group deactivator isocyanate to achieve end group deactivation. The chemical repair mechanism was explored through analyzing the microcosmic chemical structure and polarity changes of aged asphalt at each repair stage. By comparing the results to matrix asphalt, the chemical repair effects of hydrogenation reduction and end-group deactivation on aged asphalt were evaluated by the analysis and testing of dynamic viscosity and low temperature properties of aged asphalt before and after repair. The results show that the chemical structure of aged asphalt is changed by hydrogenation and passivation. The carbonyl and sulfoxide groups in aged asphalt are reduced to hydroxyl groups by triethoxylsilane, which are then esterified to ester by isocyanate. After hydrogenation and passivation, the polarity of aged asphalt significantly weakens, leading to a substantial reduction in intermolecular forces and viscosity. Consequently, the low temperature deformation capacity is significantly improved. Furthermore, a strong correlation between low-temperature properties and the functional group index of aged asphalt was observd.