A novel framework for realistic modelling of 3D mesostructure and fracture behaviour of recycled aggregate concrete

Recycled aggregate concrete (RAC) offers a sustainable alternative to natural aggregate concrete, while its meso-scale modelling is often limited by overly simplified geometries. This study presents a novel 3D computational framework using Voronoi tessellation and hierarchical clustering to realistically generate 3D mesostructure of RAC. The model equips six distinct phases including old aggregate, old mortar, new mortar, two interfacial transition zones (ITZs) and voids, and employs splining and scaling techniques to control morphology. It produces irregular recycled aggregates with realistic size distribution, volume fraction, old mortar content, and shape descriptors in terms of sphericity, roundness and convexity. Validation indicates consistence with experimental findings in terms of geometry and composition. 3D meso-scale modelling of fracture processes in RAC under uniaxial compression can accurately capture the crack initiation at old ITZs and shear-dominated failure. The proposed modelling framework offers a robust tool for understanding the mesostructure-mechanical property relationships in RAC and optimising material design of RAC.