Multiscale and multiphysics discrete model of self-healing of matrix and interfacial cracks in fibre reinforced cementitious composites: Formulation, implementation and preliminary results

This paper focuses on the numerical modelling of autogenous and stimulated healing of cracks in fibrereinforced cementitious composites, with the aim of showing the potential that a multiphysics and multi-scale discrete model has in capturing the complex hygro-thermo-chemo-mechanical processes governing concrete ageing and its capability of autonomously repairing cracks. This study expands a prior research on numerical modelling of self-healing of normal-strength concrete, to simulate the autogenous and stimulated healing of cracks in fibre-reinforced cement-based composites. The proposed extended model explicitly differentiates between (i) major cracks in the cementitious matrix and (ii) debonding cracks at matrix–fibre interface. The increased fibre-matrix bond due to the healing products along the interface cracks is explicitly implemented to capture the possibility of having a healing-induced mechanical recovery even when major cracks are totally or partially unhealed, complying with experimental evidence available in the literature. The model can also simulate the material ageing. After the model formulation and implementation in the Multiphysics-Lattice Discrete Particle Model (M-LDPM) framework, an example of calibration and validation for one of the Ultra High Performance Concrete (UHPC) mixes developed within the Horizon 2020 project ReSHEALience is presented.