A Mesoscale Multi-Phase Elasto-Plastic Phase-Field Framework for Fracture Modelling of Concrete

Concrete deterioration, driven by progressive micro-crack formations that naturally develop in concrete either due to mechanical stress or material degradation, poses critical challenges for structural safety and durability. Though capturing crack propagation in concrete elements is essential for determining damage fracture patterns and nonlinear failure mechanisms, it is complex to describe it accurately using conventional continuum mechanics approaches. This paper presents a mesoscale multi-phase phase-field framework for concrete that explicitly accounts for energy dissipation across its heterogeneous constituents. The model incorporates the Drucker-Prager yield criterion and spectral decomposition to capture plasticity and the asymmetric tensile-compressive response of cementitious materials. At the mesoscopic scale, realistic concrete geometries are generated using polygonal aggregates with a separating axis theorem-based overlap detection algorithm, enabling improved representation of aggregate shape and spatial distribution. To validate the proposed model, three sets of experiments from the literature, are utilized to explore the impact of the volume content on the properties of concrete composites. Results demonstrate that the numerical model agrees well with the experimental results from the perspectives of load-deflection curves and crack patterns, confirming its efficacy. This model offers a robust and flexible framework for predicting crack propagation in concrete with varying volume fractions of the constituents, which can efficiently incorporate the effects of multiple physical fields. This work provides an in-depth understanding of damage evolution and can be utilized to guide the development of more effective mitigation methods.