Study on damage of concrete under uniaxial compression based on electrical resistivity method

This study investigated the relationship between concrete electrical resistivity and compressive damage. The electrical resistivity and damage variable D of concrete under uniaxial compression were measured by the electrode method and ultrasonic method. The mathematical relationship between electrical resistivity and concrete damage variable D was derived. And the mechanism of change of concrete electrical resistivity under stress was explored by Nuclear Magnetic Resonance (NMR). The results showed that the electrical resistivity curve of concrete shows a phased trend of decreasing first and then increasing during loading, which corresponds to the damage evolution of concrete. The derived relationship between electrical resistivity and damage variable D is well correlated with the experimental data. Based on the NMR test results and considering the excess pore water pressure, it was found that the increase in connectivity of pore solution caused by the extruded pore solution filled cement matrix microcrack under stress may be the main reasons for the decrease in electrical resistivity of concrete specimens. Toward failure, the instability and penetration of macrocrack lead to the cutting of concrete matrix, which is the main reason for the increase of electrical resistivity. (C) 2020 Elsevier Ltd. All rights reserved.