Analysis of corrosion risk due to chloride diffusion for concrete structures in marine environment

Tristan Senga Kiesse,Stéphanie Bonnet,Ouali Amiri,Anne Ventura

doi:10.1016/j.marstruc.2020.102804

Abstract

The chloride-induced steel corrosion is one of the main causes of deterioration for reinforced concrete structures exposed to marine environments. The chloride ingress into reinforced concrete structures is even more complex since it depends on random parameters linked to transport and chemical properties of materials, which results in variability of corrosion initiation. This variation raises the need of statistical approaches to evaluate the risk of corrosion initiation due to chloride ingress. To address this issue, we use sensitivity analysis to identify the influence of input parameters on critical length of time before corrosion initiation predicted by our chloride diffusion model. Exceedance probabilities of corrosion initiation time given that input parameters exceed certain thresholds were also calculated. Results showed that the corrosion initiation time was most sensitive to: chloride effective diffusion coefficient De in concrete, that is a parameter controllable by relevant stakeholders; surface chloride concentration Cs, a non-controllable parameter depending on surrounding conditions. Reducing the chloride diffusion coefficient enables us to postpone the maintenance of structures. However, the interaction between controllable parameters and non-controllable surrounding conditions was revealed influential on the reliability of results. For instance, the probability that corrosion initiation time exceeds 15 years given an effective diffusion coefficient (De) equal to 0.1 × 10−12 m2⋅s-1 can vary from 19 to 41% according to stochastic variations of chloride concentrations (Cs) values. Postponing the corrosion initiation time was combined with a decreasing probability of its occurrence.

Highlights

Corrosion of steel reinforcement due to chloride ingress is one of the major causes of degradation of Reinforced Concrete (RC)structures [1]
This kind of approach was already developed and applied to a RC structure located in Madrid and submitted to carbonation [9]. In complement to this previous work, the present study focuses on probabilistic assessment of corrosion risk due to chloride ingress into RC structures exposed to marine environment
Results of sensitivity analysis (SA) concerning the influence of input parameters diffusion coefficient (De), xrebar, Cs,Ccrit, p and α of the studied model are given in Table 2. 3.1.1

Summary

Introduction

Corrosion of steel reinforcement due to chloride ingress is one of the major causes of degradation of Reinforced Concrete (RC)structures [1]. Corrosion of steel reinforcement due to chloride ingress is one of the major causes of degradation of Reinforced Concrete (RC). The corrosion initiation corresponds to the process of chloride ingress into concrete until the chloride concentration has reached the steel rebar and exceeds a threshold value. Steel is de-passivated and the corrosion propagates into the reinforcement. We define the service life as the period of penetration of chloride into the concrete cover until the chloride content exceeds a threshold value at the position of the reinforced steel bar. It is important to improve service life predictions, and to determine influent parameters and to evaluate levels of potential risk in order to provide recommendations for longer service life to engineering designers when designing concrete structure exposed to chloride

Methods

Results

Conclusion