Experimental and mesoscopic simulation study of size effect on splitting tensile performance of spontaneous combustion coal gangue concrete

The spontaneous -combustion coal gangue concrete (SCGAC) demonstrates different mechanical behavior compared to ordinary concrete owing to its distinct porous structure and the presence of fibrous materials in its coarse aggregates. Presently, research on the macroscopic mechanical properties of SCGAC is reasonably comprehensive; however, it falls short of fully understanding its size effect. This study examines the splitting tensile strength of cubic SCGAC specimens with three strength grades, i.e., C30, C35, and C40, and three sizes, i.e., 100 mm, 150 mm, and 200 mm; proposes a mesoscopic modeling approach based on the computer vision; analyzes the intrinsic mechanisms of splitting failure and the size effect of different strength grades on the SCGAC by utilizing mesoscopic simulation methods. Subsequently, an analysis of the size effect on the splitting tensile strength of SCGAC is conducted based on classical size effect laws. The results reveal the following: The method proposed in this study for mesoscopic modeling is recognized for its low cost, high efficiency, and accurate simulations, fulfilling the required standards for mesoscopic mechanical analysis. SCGAC, as a heterogeneous material, demonstrates significant size effect phenomena that become more pronounced with enhancements in strength grades. The Carpinter fractal size effect law is ideally suited to characterize the size effect patterns in SCGAC. This paper enhances the comprehension of the size effect of SCGAC through a combination of macroscopic experiments and mesoscopic simulations, thereby facilitating its engineering applications.