Mechanical Analysis and Fracture Mechanism of Self-healing Microcapsules in Asphalt Pavement

The multi-scale analysis method and fracture mechanics method for composite materials were conducted to study the mechanical property requirements of microcapsule in asphalt pavement and the rupture mechanism of microcapsule under microcracks. Firstly, the multi-scale model of asphalt pavement with microcapsule was established from macro to meso and then to micro-scale by discrete element method. The mechanical response of microcapsules was analyzed under heavy traffic load. Then, modified extended finite element method was used to study the crack propagation of asphalt mortar composites with microcapsule. The influence of mechanical parameters and distribution of microcapsule on the crack growth trajectories were investigated. The performance requirements of microcapsule were determined for timely breaking and releasing the self-healing agent. The results show that the contact pressure and contact tension of interior of asphalt mortar in asphalt concrete middle layer are 0.347 N and 0.093 N under 1.43 MPa tire pressure. The average contact pressure and contact tension of all microcapsules are found to be 25 mN and 7.7 mN. The fracture mechanics analysis shows that when the elastic modulus of microcapsule is smaller than that of the matrix, the microcapsule would play an important role in strengthening the crack tip fracture parameters. The micro-crack will move towards to the microcapsule, which enables the microcapsule to serve for the self-healing function. For further application of microcapsule in asphalt pavement, some advanced technologies, like nano indentation technology or atomic force microscope, can be used to measure the mechanical properties of microcapsule. © 2022, Materials Review Magazine. All right reserved.