Finite Element Modeling of Chloride Ion Ingress and Reinforcement Bar Depassivation in UHPC

Resumo

This study addresses the challenge of predicting chloride ingress in UHPC and depassivation of reinforcing steel, which is essential for durability assessment. A numerical model was calibrated using experimental data to estimate the time for chloride to reach the critical threshold (0.3%) at reinforcement depth. Simulations considered cover depths of 15, 20, and 25 mm under chloride concentrations of 0.5% and 1.95%. Results show that under low chloride exposure, the UHPC cover can protect steel for more than 100 years before depassivation, whereas under severe marine conditions, this duration drops to 16–25 years, depending on the cover. Matrix diffusivity and chloride concentration are the key parameters governing chloride ingress and the time to reach 0.3% at reinforcement depth, critically influencing service-life prediction. Numerical simulation proved efficient in overcoming the time limitations of experimental programs and supports service-life design.