多尺度研究沥青与集料界面的粘附性损伤机理

The interface between asphalt and aggregate plays as one of the most important roles to the durability of asphalt pavement. In last decades, there are few experimental studies on the interface adhesive damage at the molecular scale due to the complexity of sample preparation and the instability of the interface micro-structure. Moreover, the existing macroscopic tests didn't take the influences of multiple factors into consideration comprehensively. Meanwhile the relationship between microscopic and macroscopic experimental results cannot be analyzed sufficiently through a single theoretical model. Therefore, universal characterization methods and evaluation indexes for interface damage remain absent so far..In view of the above problems, this project intends to mainly adopt Atomic Force Microscope (AFM) and Mass Spectrometer (MS) to study the evolution of the interface molecular composition, micro-structure, morphology and micro-mechanical properties with the number of high-low temperature cycling tests, which will reveal the microscopic damage behaviors of the interface. At the macro-scale, on one hand, the tensile strength of the interface will be characterized by the Pneumatic Adhesion Tensile Testing Instrument (PATTI). On the other hand, based on the modified Dynamic Shear Rheometer (DSR), the dynamic evolution of the single/double interface fatigue damage is explored under the coupling effect of various factors, including water, temperature, loading, surface roughness of aggregates, coating shape and so on. Therefore, the evaluation index of interface damage will be put forward. At the same time, combined with the created Molecular Dynamics (MD) model, the relationship between nanoscale properties and macroscopic durability will be established. This project not only contributes to understand the adhesive damage mechanisms of the asphalt-aggregate interface in depth, but also lays experimental and theoretical foundations for the material design and performance improvement of the asphalt pavement.

沥青-集料界面对沥青路面耐久性起至关重要的作用。目前，由于制样的复杂性和界面微观结构的不稳定性，在分子尺度上针对界面粘附性损伤的实验研究较少。同时，现有的宏观试验并未全面地考虑多因素的影响，单一的理论模型无法深入分析微观与宏观实验结果的关联性，缺少适用范围广的界面损伤的表征方法和评价指标。.因此，本项目拟在微观上采用原子力显微镜、质谱仪等技术手段，研究界面的分子组成与结构、形貌特征和力学性质随高-低温循环次数的演变过程，揭示界面微观损伤行为；在宏观上，采用气压式粘附力测试仪表征界面的抗拉损伤能力，采用改进的动态剪切流变仪测试沥青-集料单/双界面疲劳损伤的动态演变，考虑水、温度、加载、集料表面粗糙度、裹覆形状等因素的耦合影响，提出界面损伤的评价方法。本项目将结合分子动力学建立微观与宏观实验的联系，深层次解析沥青-集料界面粘附性损伤机理，为提高路面耐久性的沥青材料设计提供理论基础和技术支撑。

基于微观尺度的沥青-集料界面的粘附性能对沥青路面耐久性起至关重要的作用。目前，由于制样的复杂性和界面微观结构的不稳定性，在分子尺度上针对界面粘附性损伤的实验研究较少。同时，现有的宏观试验并未全面地考虑多因素的影响，单一的理论模型无法深入分析微观与宏观实验结果的关联性，缺少适用范围广的界面损伤的表征方法和评价指标。因此，系统全面地开展沥青混合料界面微观性能的研究至关重要。本项目结合原子力显微镜（AFM）、傅里叶红外光谱（FTIR）、沥青拉拔试验（BBS）和分子动力学模拟（MD）等技术手段，多尺度研究沥青及沥青-集料界面的粘附性能。取得的主要创新性成果如下：（1）采用AFM、FTIR揭示了水热耦合条件下基质沥青、SBS改性沥青表面微观性能的演变规律，考虑水、温度、SBS改性剂等因素的影响，提出了评价指标可评价SBS改性沥青-集料界面水热敏感性，从而揭示其抗水损害能力；（2）构建沥青平均分子模型，模拟沥青与集料损伤界面分子组成、力学性质等性能随着高-低温循环次数的动态演化过程，提出了定量分析沥青与集料界面的粘附性损伤的评价指标，多次高低温循环更容易引起沥青-集料界面的粘附性失效行为；（3）结合BBS、AFM试验及MD模拟，建立了微观与宏观指标的联系，深层次解析了沥青-集料界面粘附性损伤机理，证实平均分子结构模型对模拟界面粘附性损伤及自愈合性能是合理的（4）沥青的自愈合性能与其相变温度密切相关，纳米技术可提高沥青的分子扩散能力自愈合性能。本项目为提高路面耐久性的沥青材料设计提供理论基础和技术支撑。