Insights on the ion migration throughout the nano-channel of ettringite under an external electric field: Structure, dynamics, and mechanisms. (30th November 2020)

• Record Type: Journal Article
• Authors: Li, JinHui; Gao, Lanjuan; Hou, Dongshuai; Wang, Pan; Zhou, Yang; Ding, Qingjun; Xiong, Chenchen
• Is Part Of: Construction & building materials. Volume 262(2021)
• Publication Date: 2020-11-30
• Subjects: Ettringite crystal -- Electrochemical -- Diffusion mechanisms -- Sodium immobilization; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2020.120074
• Languages: English
• ISSNs: 0950-0618

Abstract

Graphic abstract: The directional migration of ions was induced by the external electric field, which generated the current in the nano-pores of ettringite. Highlights: The directional migration of ions was induced by the external electric field, which generated the current in the nano-pores of ettringite. The magnitude of the current is proportional to the electric field intensity. The chlorides account for about 80% of the total ion current intensity. Abstract: In this research, molecular dynamics simulations were employed to unravel the transmission mechanisms of chloride ions and sodium ions throughout ettringite nanopores as exposed to an external electric field 0–0.04 V/Å. The current was generated by the directional migration of cations and anions, proportional to the intensity of electric field, among which chlorides account for 80% while sodium contributes little. The migration of sodium ions was limited as a result of the attraction from the oxygen atoms in the sulfate ions on the ettringite surface. This effect weakened due to the increase in the electric field intensity. Furthermore, the relocation rate of ions may obey in the following ranking: Cl − > Ow > Na + . The development of this work can reveal the mechanism of ion migration and diffusion inside the pores of concrete during the application of the electrochemical desalination method, which has a guiding significance for the durability design of concrete structures.