Electrochemical chloride extraction on reinforced concrete contaminated external chloride: Efficiencies of intermittent applications and impacts on hydration products

• Published in: Cement & concrete composites Vol. 121; p. 104076
• Main Authors: Nguyen, Thi Hai Yen, Tran, Van Mien, Pansuk, Withit, Cao, Nguyen Thi, Bui, Van Hong Linh
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2021
• Subjects: Applied charge number; C-S-H; C-S-H decomposition; Chloride removal efficiency; Electrochemical chloride extraction; Intermittent application; C-S-H; C-S-H decomposition; Chloride removal efficiency; Electrochemical chloride extraction; Applied charge number; Intermittent application
• ISSN: 0958-9465; 1873-393X
• DOI: 10.1016/j.cemconcomp.2021.104076

This paper aims to assess the efficiency of electrochemical chloride extraction (ECE) using the intermittent application and its impacts on cement hydration products in concrete contaminated external chloride ions. Continuous application (Mode 1) and two modes of intermittent application (Mode 2 and Mode 3) were conducted for 10 weeks. The results indicated that while the final efficiencies of chloride extraction on three modes were approximate, the charge efficiency, which is the content of chloride removed per one unit charge applied, was much greater on samples using Mode 2 and Mode 3 than that in Mode 1. Portlandite content in concrete at the electrodes increased after the treatment. The decomposition of C-S-H was proportional to the cumulative applied charge number. By using a much less applied charge number, Mode 2 and Mode 3 caused less decomposition of C-S-H in concrete than that in Mode 1. The accumulation of NaOH in concrete near the steel reinforcement was observed. Intermittent applications can apparently alleviate the adverse impacts of ECE treatment on C-S-H. Furthermore, the total cumulative charge number employed should not exceed 800–900 A h/m2. •Final efficiencies of chloride extraction in three modes of treatment were approximate.•Intermittent applications improved charge efficiency greatly in removing chloride.•Decomposition of C-S-H due to ECE can be alleviated by using intermittent treatment.•After extraction, NaOH was precipitated in concrete at steel reinforcement.•Cumulative charge applied for ECE treatment should not be greater than 800–900 A h/m2.