Influence of initial defects on crack propagation of concrete under uniaxial compression

Abstract

In order to evaluate the safety of concrete structures with the initial defect, the meso-scale mechanical characteristics needed to be studied. The uniaxial loading failure process of concrete containing expanded polystyrene (EPS) particles was studied by X-ray computed tomography (X-CT), acoustic emission (AE) and numerical simulation in this manuscript. The results show that cracks were observed preferentially at the corners and the defects close to the outside. The bearing capacity was seriously affected by splitting cracks. The location where open cracks often appear was the largest macroscopic defect in the horizontal projection. The method of prefabrication of defects was reasonable. A polygon aggregate modeling method was proposed considering statistical features. The established model can accurately describe the mechanical behavior, which verifies the consistency of meso-simulation and mechanical experiments. Several meso-scale models with cavities were provided. The size of the defect radius was positively correlated with the macro cracks and the damage degree of tension crack, but negatively correlated with the total damage parameter, the damage degree of mortar and ITZ, and the damage degree of shear crack. The size of the defect mainly plays a major role in the damage of the mortar.