Feasibility study of reactive mass transport modelling to support service life design: Numerical simulation of chloride ingress

Abstract

This report discussed the applicability of reactive mass transport (RMT) models for the durability design of concrete structures. The study focussed on supporting service life modeling of chloride-induced reinforcement corrosion of immersed concrete structures in the Norwegian coastline. First, model results were compared to experimental data of selected case studies for chloride ingress in mortar and concrete mixes. The modeled data showed a relatively good agreement with the experimental results of concrete specimens exposed to seawater in the Norwegian Atlantic coast for 25 years. Second, a parametric study was carried out to evaluate the model performance to predict the minimum concrete cover required to avoid chloride-induced corrosion of reinforcing steel in a concrete element immersed in seawater. A sensitivity study covering the main model input parameters was carried out using the Partial Least-Square (PLS) method. The results of the study indicated that model uncertainty does not solely comprise parameters that must be adjusted (e.g., the tortuosity factor) but also parameters that shall be selected based on engineering judgment. Third, a machine-learning-based regression model was trained using the parametric study results to provide a fast interpolation method between the parameter study variables. The regression model effectively provided fast and consistent interpolation between the data. The methodology presented in this study has shown an excellent potential to be implemented in existing performance-based durability models, such as fib Model Code 34, where RMT models can provide a robust physically-based transport model to replace existing analytical solutions.