Unveiling the rebar/concrete interface of reinforced concrete members with two triethanolamine derivatives under the condition of non-uniform corrosion

The rebar corrosion induced by chloride attack is a major factor threatening the durability of reinforced concrete structures in marine environments. This study examines the concrete matrix and rebar/concrete interface from eccentrically arranged reinforced concrete members incorporating two triethanolamine (TEA) derivatives, namely triethanolamine phosphate (TP) and triethanolamine dodecylbenzene sulfonate (TDS), after electrically accelerated corrosion. The chloride-contaminated concrete matrix was analyzed for microstructure, chemical composition, and pore characteristics, while the extracted rebar/concrete interfaces were evaluated through electrochemical tests, 3D profile scanning, and Vickers hardness measurements. Results show that TEA derivatives have a marked influence on the hydration products and microstructure characteristics of the cementitious materials. TDS exhibits an air-entraining effect, leading to the generation of irregular CH clusters and large-scale hydration pores that facilitate chloride penetration and accelerate steel corrosion. In contrast, TP refines CH morphology, promotes the formation of Friedel's salt, and densifies the cement matrix, thereby enhancing chloride binding and inhibiting localized anodic dissolution. Consequently, specimens with TP exhibit a significantly thinner rust layer (~15 μm) and a mechanically compact interface, ensuring superior corrosion resistance. These findings highlight the potential of phosphate-based TEA derivatives as effective corrosion inhibitors for reinforced concrete exposed to chloride-rich environments.