Reliability analysis of reinforced concrete based on Wiener stochastic process in heavy salt soil electrified environment

In order to explore the influence of corrosion ion and current on the durability of reinforced concrete in the service environment, reinforced concrete prismatic specimens of three strength grades were placed in the heavy saline soil for constant current acceleration test. The electrochemical workstation and crack detector were used for nondestructive testing regularly. The degradation process of reinforced concrete durability was analyzed by polarization curve and alternating current impedance graph. Non-monotone Wiener stochastic degradation process was selected for modeling and maximum likelihood method was used for parameter estimation. According to the crack width of concrete and crack failure criterion, the failure threshold of corrosion current density in the electrified accelerated environment of saline soil was obtained, and the relationship curve between electrified time and reliability was established. The results show that in the electrified environment of saline soil, corrosive ions enter into the concrete through diffusion, infiltration and electric field adsorption, and then migrate to the surface of reinforcement. pH value of the concrete decreases and the conductivity increases. The polarization curve moves toward the negative potential. The probability and rate of corrosion increase, and the alternating current impedance spectrum shows double capacitive reactance arc. At the beginning of power on, the arc radius of low frequency capacitive reactance decreases sharply and shrinks to the real part of impedance. When the crack width is 0.2 mm, the failure thresholds of corrosion current density of reinforced concrete for C35, C40 and C45 are 2.353, 1.817 and 1.187 μA/cm2, respectively. The higher the strength grade of concrete is, the longer the reliability is maintained at 1.0, and the stronger the anti erosion ability is. Under the coupling action of corrosive ions and current, the degree of reliability for C35, C40 and C45 specimens decrease to below 1.0 at 160, 240 and 430 h, respectively. The longer the time of power on is, the lower the reliability of reinforced concrete is. © 2020, Central South University Press. All right reserved.