A new method for studying stress-induced microcracks in concrete

The experimental technique described below makes it possible to preserve the compressive stress-induced microcracks in concrete as they exist under applied loads. The results can be used to better understand and quantify the general relationship between stress level and crack development, as well as the effect of confinement on crack behavior. Also, it allows observations into the way small cracks are formed and then propagate in concrete, thereby making the application of fracture mechanics to concrete more accurate. Cylindrical specimens of concrete were subjected to testing under uniaxial and confined compression utilizing special testing equipment designed and developed specifically for this experimental study. An alloy with a low melting point was used as a pore fluid. At a specific stress, this alloy was solidified to preserve the stress-induced microcracks as they exist under load. Scanning electron microscopy was employed to capture images from the cross sections of normal and high-strength concrete specimens.