Effects of aggregate crushing and strain rate on fracture in compressive concrete with a DEM-based breakage model

This study looked at how breakable aggregates affected the mesoscopic dynamic behavior of concrete in the uniaxial compression condition. In-depth dynamic two-dimensional (2D) studies were conducted to examine the impact of aggregate crushing and strain rate on concrete's dynamic strength and fracture patterns. Using a DEM-based breakage model, concrete was simulated as a four-phase material consisting of aggregate, mortar, ITZs, and macropores. The concrete mesostructure was obtained from laboratory micro-CT tests. Collections of spherical particles were used to imitate aggregate breakage of different sizes and shapes by enabling intra-granular fracturing between them. The mortar was described in terms of unbreakable spheres with different diameters. Compared to the mortar, the aggregate strength was always stronger. A qualitative consistency was achieved between the DEM results and the available experimental data. Concrete's dynamic compressive strength rose significantly with strain rate and just somewhat with aggregate strength. The fracture process was impacted considerably by aggregate crushing and strain rate. The number of broken contacts grew with an increase in strain rate and a decrease in aggregate strength.