Dynamic self-balanced electrochemical model for non-uniform corrosion of steel reinforcement in concrete under combined effects of heat-moisture-chlorine-oxygen

• Published in: Journal of Building Engineering 2023-12, Vol.80, p.108117, Article 108117
• Main Authors: Zhang, Guoyi, Tian, Ye, Zhao, Ruoyi, Liu, Yu, Shao, Yinzhe, Feng, Huiping, Jin, Nanguo, Jin, Xianyu, Wu, Hongxiao, Yan, Dongming, Zhou, Zheng, Wang, Shenshan, Zhang, Zhiqiang, Li, Bei, Wang, Jiaxi
• Format: Article
• Language: English
• Subjects: Artificial climate accelerated corrosion experiment; Electrochemical polarization; Multi-field coupled transmission; Steel corrosion; Time-varying environment
• ISSN: 2352-7102; 2352-7102
• DOI: 10.1016/j.jobe.2023.108117

In this study, we developed a dynamic self-balanced electrochemical model to explore the intricate interplay between coupled heat-moisture transmission and the corrosion process of steel reinforcement in concrete structures. The model accounts for the diffusion, convection, and adsorption mechanisms of chloride ions in both the cement paste and interfacial transition zone (ITZ) phases. Additionally, it incorporates the balance between gaseous and dissolved oxygen, along with oxygen consumption during cathodic reactions. This framework allows for the dynamic self-balancing of macrocell and microcell, thus offering a comprehensive understanding of the non-uniform corrosion process under various environmental factors including temperature, humidity, chloride ions, and oxygen. To validate the model, we employed comprehensive monitoring approaches, coupled with artificial climate-accelerated corrosion experiments. These were designed to record variables such as temperature, humidity, oxygen concentration, and corrosion current density under time-varying environmental conditions. Our results indicate that while temperature within the concrete remains relatively uniform, humidity exhibits a non-uniform distribution. This non-uniformity in humidity is particularly noticeable at concrete cover surface, leading to convection and accumulation effects of chloride ions. Moreover, we observe a strong correlation between oxygen concentration and relative humidity. Corrosion current density for steel rebar is found to be higher at edge regions compared to central regions, owing to varying distances from the external soaking solution. The insights gained from this research offer valuable theoretical guidance for the design, construction, and maintenance of reinforced concrete structures, particularly those exposed to marine environments. •An electrochemical model for non-uniform corrosion of steel reinforcement in concrete.•Comprehensive monitoring approaches with artificial climate accelerated corrosion experiment.•Combined effects of temperature, humidity, chloride ions, and oxygen.•Humidity variation leads to convection and accumulation effects of chloride ions.•Guidance for durability design of reinforced concrete under marine environment.