Multiscale modelling and characterization of adhesion between bitumen and aggregate

本项目重点研究沥青-骨料界面系统，即与沥青混合物中微损伤形成和水分敏感性密切相关的粘附性能。两个主要的研究关注点指导了这个项目。第一部分研究了集料的化学和形态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，在不同的环境和载荷条件下。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）进行了全面的研究，考虑了沥青和骨料的不同组合。第二个工作包中涉及的基于能量的方法用于定量描述沥青与骨料之间的粘附性能。通过接触角试验测定了沥青-骨料体系的界面粘接能，以及沥青和骨料的表面自由能。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-骨料界面行为。为此，进行了化学测试，包括薄层色谱和x射线衍射，以分别显示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，以实际骨料板代替钢测试板，从而可以直接测量沥青-骨料体系的力学性能。从而建立了考虑沥青-骨料粘结性的沥青混合料细观力学损伤模型。最后，在第五个工作包中，结合在第四个工作包中开发的微观力学损伤模型进行有限元模拟，将微观力学性能映射到沥青混合料的宏观力学性能特征上，并预测沥青（粘附）材料的行为。结合五个工作包揭示了一个基本框架（包括不同规模的实验和计算模拟），该框架将沥青-骨料系统的最重要元素联系起来。该项目的预期成果将有助于对沥青和骨料之间粘附机制的基本理解，并将在宏观层面上显著改进沥青性能的预测。

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.