Probabilistic analysis of chloride penetration in reinforced concrete subjected to pre-exposure static and fatigue loading and wetting-drying cycles

Reinforced concrete (RC) structures are subjected to environmental actions and loading that could significantly affect their serviceability and safety. Among these actions these paper focuses on the interaction between concrete cracking produced by static and fatigue loading and chloride ingress. Given the complexity of the problem and its related uncertainties, we carried out an experimental study that provided information for the probabilistic characterization of chloride ingress model parameters by accounting for static and fatigue loading effects. In the experimental part of the study RC specimens (beams) were subjected to pre-exposure loading and wetting-drying chloride exposure. At the end of the simulated chloride environmental attack, phi 100 x 120-mm cylinders were drilled out from the bottom side of the central zone of the beams and used to measure chloride profiles within the concrete cover. The probabilistic analysis of test results showed that static and fatigue loading increases both the mean and standard deviation of chloride content for concrete depths larger than 15 mm. In order to evaluate the effect of loading on modeling chloride ingress processes, experimental data was used to fit the surface chloride concentration and the chloride diffusion coefficient for an analytical chloride ingress model as random variables. The identified random variables are then used to determine the distribution of the time to corrosion initiation for the present experimental configuration and to evaluate the long-term probability of corrosion initiation for other environmental exposures and cover configurations. The overall results confirm that considering pre-exposure loading conditions has an important effect in lifetime assessment. This effect depends on the aggressiveness of the surrounding environment.