Effect of surface characteristics of aggregates on the compressive damage of high-strength concrete based on 3D discrete element method

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As the main component of concrete, aggregate has an important influence on the performance of concrete. In this study, the influence of coarse aggregate content and surface characteristics on the compressive mechanical properties and the damage evolution process of high-strength concrete were studied by using a 3D discrete element method (DEM). In order to improve the reliability of simulation results of concrete, a more accurate numerical simulation method was proposed. First, clumped-particle modules from the real aggregate geometry obtained by 3D Scanning were generated and then randomly distributed in the concrete model according to the specified aggregate content. Then the Flat-Joint Model (FJM) which can represent the micro-structure characteristics of concrete more reasonably was used to define the contact mechanical characteristics between different components. Based on this, the compressive strength, number of microcracks and damage evolution process of concrete with different aggregate surface texture factor (STF) and volume ratio were analyzed. The simulation results showed that aggregate surface texture and volume ratio were closely related to the compressive strength of concrete, and both have an exponential correlation with the compressive strength. The STF and volume ratio of aggregate have a significant effect on the proportion of tensile microcracks, and the concrete with large aggregates STF has more uniform stress distribution and wider damage range.