Multiscale modelling and characterization of adhesion between bitumen and aggregate

本项目的重点是沥青-集料界面体系，即与沥青混合料的微损伤形成和水分敏感性密切相关的粘结性能。两个主要的研究问题指导了这个项目。第一个问题是关于集料的化学和形态的非均质性及其对沥青-集料界面性能的影响。第二个问题是基于细观力学(本构)模型的宏观性能预测，在不同的环境和荷载条件下，研究内容分为五个工作包：第一个工作包对滚动瓶试验(目前使用的方法)进行了全面的调查，考虑了沥青和集料的不同组合。第二个工作包采用基于能量的方法来定量描述沥青与集料之间的粘结性能。通过接触角测试，分别测定了沥青-集料体系的界面粘附能以及沥青和集料的表面自由能。第三个工作包将分子动力学模拟引入本项目，在原子水平上研究沥青-集料界面行为。为此，进行了包括薄层色谱和X射线衍射在内的化学测试，以分别表征沥青和集料的化学和矿物组成。在第四个工作包中，对动态剪切流变仪平台进行了改进，将钢质试验板替换为真实的集料板，从而可以直接测量沥青-集料体系的力学性能。从而可以建立考虑沥青-集料粘结的沥青混合料细观损伤模型。最后，在第五个工作包中，结合第四个工作包中建立的细观力学损伤模型进行有限元模拟，将细观力学特性映射到沥青混合料的宏观力学性能特征上，并预测沥青(粘结)材料的性能。结合这五个工作包，揭示了一个基本框架(包括不同尺度上的实验和计算模拟)，它联系了沥青-集料系统中最重要的因素。该项目的预期成果将有助于从根本上理解沥青与集料之间的粘结机理，并将大大提高宏观层面上对沥青性能的预测。

This project has focused on the bitumen-aggregate interface system known as the adhesion properties that have an intense connection with the micro-damages formation and the moisture susceptibility in asphalt mixtures. Two main research concerns have guided this project. The first one asks about the chemical and morphological heterogeneities of aggregates and their influence on the bitumen-aggregate interface performance. The second question revolves around the macroscale performance prediction based on the micro-mechanical (constitutive) model in the face of varying environmental and loading conditions.The research content is divided into five work packages: The first work package applies a comprehensive investigation on the rolling bottle test (currently used approach) taking into account different combinations of bitumen and aggregates. The energy-based method involved in the second work package is carried out to quantitatively describe the adhesion property between bitumen and aggregate. The interfacial adhesive energy of the bitumen-aggregate system, as well as the surface free energy of bitumen and the aggregate respectively, are measured by the contact angle test. The third work package introduces the molecular dynamic simulation into this project to study the bitumen-aggregate interfacial behavior at an atomistic level. For this purpose, chemical tests, including the thin-layer chromatography and X-Ray diffraction are performed to feature the chemical and mineral compositions for bitumen and aggregates respectively. In the fourth work package, Dynamic Shear Rheometer platform is modified with the concept of replacing the steel testing plates with real aggregate plates so that the mechanical property of bitumen-aggregate system can be directly measured. Consequently, the development of micromechanical damage model for asphalt mixture concerning the bitumen-aggregate adhesion can be achieved. Finally, in the fifth work package, the Finite Element simulation incorporating the micromechanical damage model developed in the fourth work package is performed to map the micromechanical properties onto the macro mechanical performance characteristics of asphalt mixtures and to predict asphalt (adhesion) material behavior.Combining the five work packages reveals a basic framework (comprising experiments and computational simulations on different scales) that relates the most important elements regarding the bitumen-aggregate system. The anticipated achievements of this project will contribute to the fundamental understandings of adhesion mechanisms between bitumen and aggregate and will allow for significantly improving predictions of asphalt performance on the macro level.