Nonlinear behavior in the pre-peak and strain-softening phenomenon can be explained in terms of microcracks and macrocracks. Numerous microstructural features that absorb energy make concrete a quasi-brittle material. Microcracks form at relatively low stresses, and as the stress increases, the…
Nonlinear behavior in the pre-peak and strain-softening phenomenon can be explained in terms of microcracks and macrocracks. Numerous microstructural features that absorb energy make concrete a quasi-brittle material. Microcracks form at relatively low stresses, and as the stress increases, the microcracks tend to localize into macrocracks that ultimately to specimen failure. Experiments to study the compressive fracture of lead cement-based materials were conducted. The permeability or durability of concrete is directly related to the formation of microcracks, and thus accurate observation is essential. Microcracks, which are the precursors of macrocracks, form at early stages of stress and cannot be easily detected due to small sizes. Computer vision, which is based on digital image correlation, was used to measure microcrack openings. The authors dramatically improved the accuracy by increasing the image resolution. The microcrack propagation near aggregates was examined with subregion scanning computer vision. The formation of cracks were monitored through several loading steps. Nonuniform local displacements were observed with different end conditions as well as with different material composition.