Reliability life analysis of reinforced concrete in a salt corrosion environment based on a three-parameter Weibull distribution

To study the corrosion law and life distribution of reinforced concrete in a coupled salt environment, the reinforced concrete specimens were placed in 0.32 mol·L⁻¹ NaCl and 0.4 mol·L⁻¹ MgSO₄ salt solutions. The performance of reinforced concrete was tested regularly using an electrochemical workstation. The durability was analyzed through a polarization curve, an AC impedance spectrum, and electrochemical parameters. A three-parameter Weibull distribution was selected for reliability modeling, and a prior false test was performed by the Anderson-Darling (A-D) method. The parameters were estimated by the correlation coefficient optimization method (CCOM), maximum likelihood method (MLM), and moment estimation method (MEM). The reliability curve, density curve, and failure rate curve were each used to analyze the life of reinforced concrete in chloride, sulfate, and magnesium-based corrosion environments. Results show that under the combined action of corrosion ions, the polarization curve gradually moves toward increasing corrosion current density and negative potential, and the AC impedance spectrum moves to the left and shrinks to the real part of the impedance. The resistance of steel bar corrosion gradually decreases whereas the probability gradually increases. The reliability curve is unchanged at the initial stage and rapidly decreases at the later stage. The density curve is symmetric with a single peak, and the failure rate curve remains unchanged at the initial stage and increases linearly at the later stage. Among the three-parameter estimation methods, CCOM and MLM parameter estimation values are similar, stable, and accurate, and the obtained reliability curves are similar. It is suggested that CCOM and MLM should be used for parameter estimation and reliability analysis of small sample failure data that is obtained from an accelerated test of reinforced concrete. The reliability life of C35 reinforced concrete in magnesium sulfate and sodium chloride corrosion environments is about 760 d.