基于再生剂分子材料设计原理的热再生沥青混凝土低温开裂机制研究

The north of China is an important area of the Silk Road on land according to the country development strategy of "The Belt and Road". In order to solve the bottleneck problem of transportation existing in the realization of this strategy, the highway infrastructure in this region urgently needs to be repaired, reconstructed and upgraded. The hot recycled asphalt pavement technology, as a main technical measure for developing green and sustainable transportation, must play an important role in the upgrading of the highway infrastructure. As the aging of asphalt binder and the low air temperature could induce the brittle of asphalt mixture, the thermal cracking issue of the hot recycled asphalt concrete would play a key role in determining the durability of asphalt pavement. Therefore, the objective of this project is to improve the thermal cracking resistance of hot recycled asphalt concrete, by conducting the reasonable material design of rejuvenator which is rather important in realizing the addition of high percentages of recycled asphalt pavement and the rejuvenation of asphalt concrete in the same layer. The multi-scale test tools and molecular simulation theory would be utilized to investigate the influencing factors and interaction mechanism of the diffusion characteristics between the rejuvenator and various asphalt, and the adhesion-debond mechanism between the rejuvenated asphalt and mineral aggregate. Finally, the molecular material design principle of rejuvenator and the improvement theory of the thermal cracking resistance of hot recycled asphalt concrete could be developed based on the diffusion and adhesion characteristics. The research can help to supplement and optimize the basic theory of the hot recycling technology, and also provide a strong technical support to the construction of the transportation network of "The Belt and Road".

北方地区是国家“一带一路”发展战略中陆上丝绸之路的重要组成部分。在此背景下，亟需对该区域现有公路基础设施升级改造，以解决发展中的交通瓶颈问题。作为发展绿色可持续交通的主要技术措施，沥青路面热再生在公路升级改造中将发挥重要作用。由于结合料老化和低温易导致混合料脆化，该地区热再生沥青混凝土的低温开裂将是制约沥青路面长期耐久的重要因素。针对此，项目以改善热再生沥青混凝土的低温抗裂性为目标，以实现高掺量旧料和原位再生极为重要的再生剂材料设计为核心，借助多尺度测试工具与分子模拟理论，明确影响再生剂与新旧沥青扩散融合特性的因素及其作用规律，揭示再生沥青与矿料的界面粘附-脱附机制，最终系统提出基于扩散融合改善与界面粘附增强特性的再生剂分子材料设计准则和热再生沥青混凝土低温抗裂性提升理论。研究有助于补充完善寒区沥青路面热再生过程中的基础性理论问题，为“一带一路”交通网络的顺利构建提供强有力的技术支撑。

我国北方冬季寒冷且温差大，材料温度收缩情况严重，再生沥青路面势必面临低温抗裂的重要技术需求。因此，如何增强再生沥青路面抵抗低温开裂的能力，丰富沥青路面再生技术的理论基础，提高旧沥青路面材料的循环利用率，实现路面再生材料的原位利用，是亟待解决的重要议题。本项目从沥青老化机制出发，立足于沥青/再生剂的融合扩散问题，从材料分子设计角度提炼总结沥青再生剂分子属性特征，为再生剂的分子设计提供进一步优化依据，基于此提出再生剂优化设计方法，选取代表性材料制备再生剂，分析热再生沥青混凝土路用性能及其演化规律，同时建立基于界面融合的再生剂性能评价方法，构建相应评价指标及混合料性能之间的关系。重点针对热再生沥青混凝土低温抗裂性能，明确热再生沥青混凝土低温环境中温度裂缝的产生机制、演化过程和控制措施。研究借助多尺度测试工具与分子模拟理论揭示了再生剂与新旧沥青扩散融合机制和黏附机制，系统地提出基于扩散融合改善与界面粘附增强特性的再生剂分子材料设计准则和热再生沥青混凝土低温抗裂性提升理论。本项目可为寒区热再生沥青混凝土的大面积推广与应用奠定理论基础，为“一带一路”交通网络的顺利构建提供强有力的技术支撑。