Safety Analysis of Rebar Corrosion Depth at the Moment of Corrosion-Induced Cover Cracking

Concrete cover cracking induced by reinforcement corrosion is an important indication of the durability limit state for reinforced concrete (RC) structures and can be used to determine the structural service life. The process of rebar corrosion from the beginning of rusting to the occurrence of cover cracking due to corrosion expansion can be divided into two phases: the phase of the free expansion of the corrosion product and the phase of cover cracking. Based on the assumption of the uniform corrosion of the reinforcement, one model for predicting the reinforcement corrosion depth from corrosion initiation to cover cracking was established according to the cylindrical cavity expansion theory. The main factors affecting the reinforcement corrosion depth were analyzed. The main factors affecting the corrosion depth of reinforcement were analyzed. The quantitative sensitivity analysis of the factors influencing the calculation formula shows that the depth of reinforcement corrosion and the thickness of the concrete protective layer are approximately linearly increasing, with a growth rate of 0.2366 μm/mm; the diameter of the reinforcement is approximately linearly decreasing, with a decrease rate of 0.2122 μm/mm; the volume expansion rate of rust is approximately power function decreasing; the overall influence range of the yield criterion selection parameter is 0.15 μm; for the concrete strength grade, the overall influence range is 0.1 μm. The coefficient of determination R2 is 0.87, and the overall accuracy of the calculated formula is high, which can be used to predict the service life of reinforced concrete structures and guide the durability design in combination with the research results on the corrosion rate of reinforcement under different environments.