Randomness of critical chloride concentration of reinforcement corrosion in reinforced concrete flexural members in a tidal environment

Abstract

In this paper, the free chloride concentrations at different depths and the corrosion rates of tensile reinforcements in tensile concrete zone of reinforced concrete (RC) beams under flexural loads in a simulated and natural tidal environment are tested. By considering the influence of time-dependent reinforcement corrosion, the time to corrosion initiation and critical chloride concentration (Ccr) in tensile concrete zone of RC beams under different exposure conditions can be obtained. The probability distribution forms of Ccr of tensile reinforcement corrosion initiation subjected to different exposure environments and flexural load levels have been compared by using the Kolmogorov-Smirnov (KS) hypothesis test method. Results indicate that the values of Ccr from the field exposure tests are lower than those obtained from the artificial simulation experiments. In a natural tidal environment, the chloride transport in concrete shows a stronger randomness, and the effect of flexural loads on the probability distribution forms of Ccr are also more significant. Moreover, under the flexural loads, Ccr in the simulated and natural tidal environment obeys a Gumbel distribution with mean value of 0.382% by weight of concrete and a Normal distribution with mean value of 0.328% by weight of concrete, respectively. However, without flexural loads, the values of Ccr in the simulated and natural tidal environment are found to follow a Gumbel distribution with mean value of 0.572% by weight of concrete and a Log-normal distribution with mean value of 0.356% by weight of concrete, respectively.