New semiempirical temporal model to predict chloride profiles considering convection and diffusion zones

Chloride ions are primarily responsible for reinforcement corrosion in concrete structures in the marine envi-ronment. Thereby, analyses regarding chloride penetration into concrete are fundamental for service life esti-mates, in which the chloride concentration profiles provide quantitative information for prediction models. However, the conventional modeling method based on the solution of Fick's second law of diffusion usually only fits the diffusion profile zone and does not represent the convection zone. Therefore, this article shows a new model for complete chloride profile modeling. The semiempirical double exponential model was developed by approximating Fick's second law using the finite difference method and validated with chloride profiles from structures under natural degradation for more than 40 years. The double exponential model proposed can fit in the two profile zones, showing higher efficiency than Fick's model, and stands out for expressing the variation in chloride peak depth over time.