Discrete Element Method Simulation of Aggregate Interlock Effects in Concrete with Real Rough Interfaces under Shear Loading

Abstract

It is well known that aggregate interlocking is an important contributing mechanism to the shear capacity of concrete. In this study, 3D discrete element method is employed to elucidate how aggregate interlock affects the shear transfer and interfacial behavior of real rough concrete interfaces. Starting from a high-resolution Stereolithography (STL) model of the crack surface the roughness geometry is imported into discrete element model (DEM) as a rigid boundary while the surrounding concrete is discretized into bonded spherical particles. The shear-slip simulations show that the contact force chain is concentrated near the sharp corner peaks, producing localized dilatation and progressive microcracks. Simulation of experimental displacement-load curves, where the peak shear strength increases nearly linearly to a critical value beyond which particle fragmentation at the surface limits further increases, provides an explanation for the aggregate damage phenomena observed in the pushover tests. By tracking bond fracture and slip localization, the model provides interpretable evidence to explain the interfacial shear resistance of recycled aggregate concrete (RAC) and natural aggregate concrete (NAC). It demonstrates the applicability of discrete element model for real rough interface in numerical simulations of aggregate interlock. It also highlights the differences in DEM results between RAC and NAC, which reflect shearslip through real rough interfaces.