Influence Mechanism Of Aggregate-Asphalt Interface Interaction Based On Dynamic Shear Rheometry

Asphalt pavement mixture is a multi-phase heterogeneous material composed of asphalt binder,aggregates and voids.The asphalt-aggregate interface plays a key role in the bonding mechanism and overall structural properties of the asphalt mixture.In recent years,scholars at domestic and abroad have mostly considered the influence of asphalt components and aggregates on the adhesion,but did not consider the evaluation of asphalt performance under the condition of aggregate adhesion,and the mechanism of the interaction between aggregateasphalt interface on the mechanical properties of asphalt is not yet clear.In order to study the influence of the interaction between aggregate and asphalt,the microscopic morphological differences of the aggregate surface were analysed using scanning electron microscopy and atomic force microscopy;the differences of the mineral composition of the aggregate were compared using X-ray diffractometer;after obtaining the mineral composition of the aggregate,the wettability of asphalt on the surface of granite,limestone and basalt under medium and high temperature conditions was compared;based on the prepared The dynamic shear rheometer test platform was constructed based on the prepared aggregate parallel plates,and the dynamic shear rheometer test and direct tensile test of asphalt under aggregate adhesion conditions were completed.The main findings are as follows:(1)The results of atomic force microscopy and scanning electron microscopy show that the microscopic morphology of the granite,basalt and limestone are very different,and the narrow band distribution on the surface of the limestone interferes with the flow filling of the bitumen,indicating that the microscopic coating effect between the bitumen and the aggregate is highly dependent on the type of aggregate.The mineral composition of limestone is dominated by calcite which has a higher adsorption capacity with asphalt.The contact angle results show that the limestone is optimally infiltrated with bitumen under medium temperature conditions and the basalt is optimally infiltrated with bitumen under high temperature conditions.(2)From the frequency scan test and the direct tensile test,it is clear that microform and chemical composition are the most important factors influencing the strength of the aggregate-asphalt interface interaction.The effect of the interaction on the mechanical properties of the asphalt depends on the loading mode(shear vs.tensile),temperature/frequency and interlayer thickness.In shear mode,the complex shear modulus decreases with decreasing interlayer thickness,while in tensile mode,the tensile strength decreases with increasing interlayer thickness.In both the shear and tensile modes,the microstructure of the aggregate is the dominant factor for the critical thickness of the interface.(3)Through the research on the high temperature,medium temperature and low temperature performance of aggregate-asphalt-aggregate interlayer,it is found that the limestone-asphalt interface interaction with strong chemical adsorption improves the intermediate temperature and low temperature performance of asphalt,and the mechanical meshing slightly stronger basalt-asphalt interface interaction Improve the high temperature performance of asphalt.