The role of particle morphology on concrete fracture behaviour: A meso-scale modelling approach

Concrete is the most-used cementitious material and usually considered a three-phase composite with a mortar matrix, aggregates, and interfacial transition zones, all of which can fracture and even fragment. In this paper, the combined finite and discrete element method (FDEM) benchmarked with an in-situ X-ray micro-computed tomography and diffraction experiment is applied to bridge this gap in the meso-scale concrete fracture behaviour. To this end, algorithms are developed for realistic-shaped particle, packing, and high-quality FEM mesh- generation based on Voronoi tessellation and spherical harmonics. Using comprehensive simulations of virtually generated meso-scale concrete samples, it is found that rough particulates in concrete can increase its stress bearing capacity by enhancing intra-aggregate fracture paths. Results show that, the hierarchical aggregate morphology expressed by the fractal dimension more directly determines the compressive strength. Among the accessible conventional shape indices, convexity is the most effective parameter to correlate the global concrete fracture stress. •FDEM benchmarked with XCT and diffraction was used to simulate concrete fracture.•A packing algorithm to explicitly model realistic particle morphology was introduced.•High-quality FEM meshes were generated with the aid of the improved SH function.•Fractal dimension is the key morphology factor influencing concrete fracture.