Mesoscale Fracture Evolution in Concrete: Insights from GPU-Accelerated 3D Discrete Element Simulations with Realistic Aggregate Morphologies

Abstract

Deciphering the fracture mechanisms of concrete at the mesoscale is pivotal for predicting the structural integrity of quasi-brittle materials. This study develops a high-fidelity 3D discrete element method (DEM) framework, characterized by real-shaped, crushable aggregates and a sophisticated contact constitutive model designed to address the inherent limitations of traditional DEM, such as insufficient compression-to-tension ratios and the lack of softening effects. Implemented on the open-source platform MUSEN with GPU-accelerated computing, the model enables large-scale simulations of wedge splitting tests (WST) with unprecedented efficiency. Validation against laboratory experiments confirms the model’s capability to capture the macroscopic mechanical response and the intricate F–CMOD relationship. Through the evolution of internal principal stress fields, the study clarifies how boundary-induced end effects and mesoscopic heterogeneity govern crack initiation and propagation. Furthermore, a parametric analysis of aggregate and interfacial transition zone (ITZ) strengths reveals a fundamental transition from transgranular to intergranular failure modes. The results quantify the crack-bridging and toughening mechanisms provided by aggregates, providing a robust computational tool for the multiscale design and safety assessment of concrete structures.