Nanoparticle Injection into Concrete Using Electromigration

Abstract

This paper aims at investigation of possibilities and effectiveness of chloride extraction from concrete and nanoparticle injection into existing reinforced concrete structures by means of electromigration technique. Concrete specimens are exposed to accelerated chloride penetration tests in order to simulate a natural chloride exposure. The developed chloride profile is removed by electroextraction by reversing the polarity in the testing chamber. In a similar manner, concrete specimens are injected with different concentrations of colloidal nanosilica particles. It was shown in the paper that chlorides can be effectively extracted from the concrete using small voltage lasting for several days. Higher concentration solutions of nanosilica can also be effectively transported into concrete via the electric field. Once injected nanosilica can act as microstructure densifier and further reduce chloride penetration as demonstrated by decreased diffusivity of the treated concrete.

Mitigation of chloride induced corrosion in reinforced concrete structures and its modeling

“…Non-destructive extraction of chlorides from the concrete can be significantly accelerated by electrochemical methods that involve application of an external electric field. In the lab, extraction of chlorides is realized in electromigration cells consisting of electrolyte filled upstream and downstream chambers with embedded electrodes connected to an external electric source [7]. On a structure, the electric circuit is realized between the steel rebars and externally attached net electrode that is placed in a conductive environment [9].…”

“…A novel method of repairing concrete is based on electromigration of nanoparticles [6][7][8]. The injection decreases concrete permeability and slows subsequent penetration of chlorides toward rebars down.…”

“…The injection decreases concrete permeability and slows subsequent penetration of chlorides toward rebars down. Works on electromigration of nanosilica [21,22] which is an anionic particle in the colloidal form or a few cationic nanoparticles can be found in the literature [6][7][8]. Colloidal nanoparticles are small particles, typically 5-50 nm in diameter, with a surface charge that can be utilized for their transport.…”

“…None of them is easy and long-lasting. Reverting corrosion in the first and second stages can also be performed via several non-destructive methods such as lowering chloride concentration in concrete by electrochemical chloride removal [2], electro-migration of corrosion inhibitors towards reinforcement [3][4][5] or injection of nanoparticles into concrete [6][7][8]. Some of the processes can be applied simultaneously, e.g.…”

Experimental Studies of Accelerated Chloride Transport in Concrete

“…Electrochemical extraction [7,8] is one of the solutions that can be used to repair reinforced concrete structure already attacked by chlorides. Besides chlorides, other particles with the charge, such as corrosion inhibitors or nanoparticles, can also be transported via electric field [8,[11][12][13]. The convective flux of ions caused by the electromotive force is much larger that the diffusive flux and leads to radical shortening of the time needed for extraction of chlorides from the structure.…”