3D RBSM-based mesoscale simulation on the fracture behavior of high-strength concrete under compression: considering aggregate strength grade and shape

Unlike the compressive failure mode of normal-strength concrete (NSC), high-strength concrete (HSC) exhibits highly brittle behavior accompanied by the trans-granular fracture of aggregate. To better understand the mechanical and fracture behavior of HSC, the evolution mechanism of internal cracks is of crucial importance but difficult to obtain by experimentation. To this end, a three-dimensional (3D) mesoscale model is developed in this study to simulate the failure process of HSC under quasi-static compression using a discrete numerical simulation method named Rigid Body Spring Model (RBSM). On this basis, the internal cracks of each constituent phase (mortar, aggregate, and interfacial transition zone-ITZ) can be quantitatively characterized by the area of cracked element faces. Following the validation of the numerical model by comparing simulation and existing test results, the effects of aggregate strength grade and shape on the performance of HSC under compression are investigated. Qualitatively, the simulation results align with the experimental data in terms of the impact of the aforementioned variables on the performance of HSC. More importantly, through the quantitative analysis of the internal cracking development during loading, the differences in macroscopic mechanical behavior between concrete models can be well explained. The mesoscale concrete modeling method developed in this study is significant to the research on cracking behavior of concrete.