乳化沥青冷再生混合料长期性能劣化机理及衰变规律研究

Due to the characteristics of material composition, construction process, and service environment for cold recycled (CR) asphalt mixture with emulsion, the fatigue cracking behavior of CR asphalt pavement becomes complex; The present studies on the long-term performance of CR asphalt mixture mainly focused on the macro laboratory study. However, these studies cannot quantify the evolution of micro-structure and damage mechanic parameters for CR asphalt mixture under the combined action of load and environment. Based on multi-scale analysis method, the chemical composition, molecular distribution and apparent morphology of emulsified asphalt-cement binder were obtained by micro-test method in this project; Damage mechanics parameters of emulsified asphalt-cement mortar were studied based on viscoelastic continuous damage model. Moreover, the evaluation indexes of coarse aggregate, contact line, void and mortar distribution were obtained by morphological analysis; The macro fatigue behavior of CR asphalt mixture with emulsion was studied by tension-compression fatigue test. In addition, considering the correlation between the initial structure and fatigue damage parameters at different scales, combined with the principle of micro-strain gradient and anisotropy, the mechanism of long-term performance deterioration for CR asphalt mixture was established by static analysis; According to the multi-factor fatigue life test method, the failure law of CR asphalt mixture with emulsion under the overall failure mode was explored by dynamic analysis, which provides basic theoretical support for the durability improvement of CR asphalt mixture with emulsion.

乳化沥青冷再生混合料的材料组成、施工工艺及服役环境的特殊性导致了其疲劳损伤行为的复杂性。目前，针对冷再生混合料长期性能的研究主要偏重宏观疲劳试验，难以定量分析荷载和环境耦合作用下冷再生混合料微细观结构与损伤力学参数的演化规律。本项目基于多尺度分析方法，采用微观试验获取乳化沥青-水泥胶结料的化学成分、分子分布、表观形态等；基于粘弹性连续损伤模型，研究乳化沥青-水泥砂浆的损伤力学参数。通过形态学分析，获取乳化沥青冷再生混合料粗集料、接触线、空隙以及砂浆分布等评价指标；采用拉压疲劳试验，研究乳化沥青冷再生混合料的宏观疲劳行为。考虑不同尺度上的初始结构与疲劳损伤参数之间的相关性，结合微观应变梯度和各向异性原理，采用静态分析，建立材料长期性能的劣化机理；根据多因素疲劳寿命试验方法，采用动态分析，探究乳化沥青冷再生混合料在整体失效模式下的衰变规律，为乳化沥青冷再生混合料耐久性的提升提供基础理论支撑。

乳化沥青冷再生混合料在干线公路的中下面层能够有效地延缓反射裂缝，目前针对乳化沥青冷再生混合料的长期性能及劣化机理，尤其是重复荷载作用下的疲劳损伤机理与衰变规律还缺乏研究。本研究旨在通过多尺度的试验及虚拟数值仿试验，在考虑乳化沥青冷再生混合料的损伤及愈合规律的同时，研究了乳化沥青冷再生混合料的长期性能劣化机理及衰变规律。本研究首先基于多尺度分析方法，采用微观试验获取乳化沥青-水泥胶结料的化学成分、分子分布、表观形态等，采用分子动力学方法，从纳微观角度探究沥青分子内的相互作用机理，从根本上了解沥青材料的性能，研究了沥青混合料微观视角下的接触行为；之后通过CT无损扫描技术获取乳化沥青冷再生混合料的细观结构和粗集料接触结构的评价指标，研究了疲劳试验过程中粗集料接触结构演变规律；其次基于分子动力学模拟的手段，模拟分子水平下沥青与集料界面的拉拔试验，研究了乳化沥青与集料界面在拉力作用下的力学响应行为；基于纳-微-细-宏观跨尺度研究乳化沥青材料的疲劳行为，考虑了不同尺度上的初始结构与疲劳损伤参数之间的相关性，采用有限元方法根据不同尺度下的乳化沥青混合料的疲劳开裂行为，建立了道路基础设施沥青基材料-结构一体化的材料长期性能评价体系；根据多因素疲劳寿命试验方法，基于离散元方法预估了乳化沥青冷再生混合料细观结构的疲劳寿命和失效模式下的衰变规律。本研究为深刻认识冷再生沥青混合料的疲劳损伤机理，准确评价冷再生沥青混合料的疲劳性能，分析乳化沥青冷再生混合料长期性能的劣化机理和衰变规律提升提供基础理论支撑。