Study on the Influence of Stray Current on Ion Migration Under Multi-factors

The purpose of this study is to explore the migration law of chloride ions and sulfate ions under the action of electric field, and to evaluate the influence of stray current on the deterioration process of concrete under the coupling of multiple factors. Through multi-factor coupling test, 0 V~40 V direct current was applied to the concrete specimens with built-in steel bars, and they were placed in 3% NaCl solution and 3% NaCl+1% Na₂SO₄ mixed solution, respectively. Ion concentration distribution and microstructure of hydration products were obtained by ion chromatography and scanning electron microscopy. The results show that the stray current significantly accelerates ion migration. The higher the voltage, the greater the penetration depth and concentration of chloride ions and sulfate ions. When the voltage is 40 V, in the depth range of 25 mm~30 mm, the chloride ion content in the single salt system is 0.395%, and the chloride ion content and sulfate ion content in the mixed salt system are 0.195% and 0.2030%, respectively. The sulfate reaction product fills the pores and changes the microstructure of the concrete, thereby inhibiting the penetration of chloride ions, and the maximum decrease of chloride ion concentration at the same depth can reach 87%. Studies have shown that electromigration is the main cause of accelerated ion intrusion; the sulfate ion reaction has a double effect, and the concrete is compacted first and then destroyed. The stray current shortens the time of each stage of sulfate attack and aggravates the deterioration of concrete durability.