Chloride ion control of under-constructing concrete structure based on ECE with different electric field intensities

Abstract

Electrochemical chloride extraction (ECE) technology can effectively reduce the harmful chloride ions in concrete and decline the durability failure risk of concrete structures. In this study, early-age sea-sand concrete was treated by ECE with strong electric field and conventional electric field, respectively. The chloride ion content analysis and microscopic observation were adopted to evaluate the durability improvement effect with ECE treatment. The results showed that at the early ages of 3, 5, and 7 d, the chloride ions were drastically reduced upon the application of a strong electric field for 40, 80, and 120 min or the conventional electric field for 15 d. Treating time of ECE with strong electric field is 0.19 %–0.56 % of that of ECE with conventional electric field. Under a strong electric field, the distribution of residual chloride ions in specimens was more uniform. Application of an electric field during the curing period caused the directional migration of ions and subsequently changed the pore structure and microhardness of the specimen. However, these changes were recovered with the continuous hydration of concrete during the curing period. Finally, based on engineering cases, the field implementation schemes of the strong electric field and conventional electric fields were analyzed. The energy consumption of ECE with strong electric field is 17.8 %–53.3 % of that of ECE with conventional electric field. The results of this study provide the technical means for the timely treatment of excessive chloride ion concentration in sea-sand concrete structures.