Mesomechanism of the dynamic tensile fracture and fragmentation behaviour of concrete with heterogeneous mesostructure

As a typical multi-phase material, due to its heterogeneous mesostructure, concrete exhibits complicated mechanical responses when subjected to high-rate loads. Considering concrete is much weaker in tension than in compression, it is of significance to investigate the mesomechanism of the dynamic tensile fracture behaviour of concrete under high-rate loading conditions. In this study, the meso-heterogeneity of concrete is considered by random mesostructure generation with efficient algorithm of Entrance block between A and B (E(A, B)). A 2D meso-scale model is developed by implementing a combined FDEM scheme with zero-thickness cohesive elements in ABAQUS software. The proposed model is validated by quasi-static uniaxial tension and uniaxial compression tests as well as dynamic Brazilian tensile split Hopkinson pressure bar (SHPB) test and then used in a series of Brazilian tensile SHPB tests to investigate the influences of the loading rate, aggregate area fraction and the mechanical properties of the interfacial transition zone (ITZ) on dynamic tensile behaviour of concrete. The numerical results indicate that the dynamic tensile strength increases with increasing loading rate and the fragmentation experiences a transition from parse fracturing to dramatic pulverization. A higher aggregate content has an adverse effect on the dynamic tensile strength of concrete. Moreover, the results also suggest that the mechanical properties of the ITZ play a significant role on the dynamic tensile behaviour of concrete. (C) 2019 Elsevier Ltd. All rights reserved.