Characterizing Splitting Failure of Concrete Influenced by Material Heterogeneity Based on Digital Image Processing Techniques

Concrete, as a composite material, is subject to heterogeneity in its mechanical properties and damage characteristics responding to load. In this paper, a numerical approach for analyzing the heterogeneous characteristics and the mechanical behavior of concrete specimens in tensile splitting tests using DIP techniques is introduced. The experiment involves the preparation of three types of concrete specimens with different strengths and performances of the tensile splitting test. The contour and position information of the different components in the split surface of a concrete specimen are reflected in the numerical model using the DIP techniques and the fracture of the split surface is realized by three types of cohesive elements in the finite element software ABAQUS. The results of the proposed numerical model are highly consistent with the experimental results with a maximum error of 4.77%, whereby the evolution of the splitting process is discussed. The simulation shows that the concrete fracture develops from the periphery towards the center of the concrete and the ITZ region splits first at similar strain levels, followed by the mortar region and finally the aggregate region. In addition, a simplified modeling scheme with faster computational efficiency and higher accuracy is proposed, which indicates that the shape of the heterogeneous components in concrete has a low effect on mechanical strength. The proposed model can accurately reflect the splitting fracture process of concrete which is instantaneous in the actual process, contributing to the understanding of the mechanism of the splitting fracture process and proposing a new methodology for simulating the fracture process of heterogeneous materials (e.g., concrete, rock). This work contributes to the understanding of the effect of material heterogeneity on concrete’s mechanical behavior and fracturing process and provides valuable hints for the research on the non-destructive prediction of concrete strength.