Abstract 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.

中文翻译：

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颗粒形态对混凝土断裂行为的作用：一种中尺度建模方法

摘要 混凝土是最常用的胶凝材料，通常被认为是具有砂浆基体、骨料和界面过渡区的三相复合材料，所有这些都可以破裂甚至碎裂。在本文中，以原位 X 射线显微计算机断层扫描和衍射实验为基准的有限元和离散元组合方法 (FDEM) 被应用于弥合中尺度混凝土断裂行为中的这一差距。为此，基于 Voronoi 细分和球谐函数开发了用于逼真形状的粒子、堆积和高质量 FEM 网格生成的算法。使用虚拟生成的中尺度混凝土样品的综合模拟，发现混凝土中的粗糙颗粒可以通过增强骨料内断裂路径来增加其应力承受能力。结果表明，分形维数所表示的分级骨料形态更直接地决定了抗压强度。在可获得的常规形状指数中，凸度是关联整体混凝土断裂应力的最有效参数。