Study on the damage cracking characteristics of cement-stabilised macadam base material: experiments and simulations

Fracture characteristics of semi-rigid bases significantly influence pavement service performance. However, understanding the multi-scale damage evolution from mesoscopic interfacial debonding to macroscopic crack propagation remains challenging. This study investigates the fracture characteristics of cement-stabilised macadam using semi-circular bending tests integrated with acoustic emission and digital image correlation techniques. A parallel discrete element method model was developed to elucidate mesoscopic energy dissipation mechanisms. Results reveal that the fracture process evolves through three stages: elastic deformation, microcrack coalescence and unstable propagation. A Weibull-based acoustic emission energy-damage model was established, identifying a critical displacement threshold of 0.335 mm for damage initiation. Furthermore, Gaussian mixture model analysis of acoustic emission signals, corroborated by digital image correlation strain fields, confirms that tensile failure dominates the fracture process, while the interfacial transition zone serves as the primary weakness for energy dissipation. This study establishes a quantitative multi-scale framework for monitoring and predicting fractures in semi-rigid bases.