Organic corrosion inhibitor of triethylenetetramine into chloride contamination concrete by eletro-injection method

• Published in: Construction & building materials 2016-07, Vol.115, p.602-617
• Main Authors: Xu, C., Jin, W.L., Wang, H.L., Wu, H.T., Huang, N., Li, Z.Y., Mao, J.H.
• Format: Article
• Language: English
• Subjects: Analysis; Cement; Chemical inhibitors; Corrosion; Corrosion inhibitor; Electric fields; Electrolysis; Electrolytes; Methods; Organic inhibitor; Rust; Steel
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2016.04.076

•TETA as a corrosion inhibitor was capable of being effectively injected into concrete.•The TETA concentration around the rebar was adequate to provide corrosion protection.•Both BIEM and ECE will reduce overall porosity in concrete cover.•Pore distribution in concrete cover will change after BIEM and ECE treatments.•Surface strength reduction is more obvious for carbonizated concrete after BIEM. Triethylenetetramine (TETA), a corrosion inhibitor for steel in aqueous media, was introduced into chloride-contaminated concrete specimens using a novel method called bidirectional electromigration rehabilitation (BIEM). An electric field was applied between the embedded steel cathodes and external anodes to inject the corrosion inhibitor from the external electrolytes to the concrete specimens and extract the chloride ions from the concrete cover zone. After treatment, the specimens were drilled to determine the concentration profiles of the corrosion inhibitor, chloride, and hydroxyl ions within the concrete. Effects of variations in the applied current density, duration of electrolysis, water/cement ratio, initial chloride content, and surface carbonation on the concentration profiles of the proposed ions were determined. Electrochemical chloride extraction (ECE) was applied as a control experiment using saturated Ca(OH)2 solution as an external electrolyte. As expected, the chloride content decreased and alkalinity increased after treatment. The concentration of the inhibitor injected around the embedded steel bars was adequate to provide corrosion protection. Concrete strength and pore distribution were measured before and after the electrochemical process was applied. The ability of TETA to inhibit further corrosion after BIEM treatment was also analyzed. The effects of BIEM and ECE were also compared. The results obtained can provide a direction in designing the BIEM process.