Electrochemical Chloride Extraction Method to Control and Mitigate Corrosion in Rebar Embedded in Concrete

Abstract

This study determines the effectiveness of the electrochemical chloride extraction (ECE) method on a bridge deck with a high concentration of chloride. ECE was applied on a pedestrian bridge in Iowa to control and mitigate corrosion that occurred in the embedded reinforcing steel. First, chloride content was measured from the existing bridge deck; it ranged from 1.64 lbs/cy to 24.58 lbs/cy. ECE was applied to remove chloride from the bridge deck for 8 weeks. Afterward, chloride content was significantly reduced to 0.32 lb/cy and to 4.96 lb/cy. To simulate corrosion in the bridge deck, 2 reinforced slabs and 12 reinforced beams were prepared, cracked, and saturated with salt solution for 4 months, followed by ECE application. Initially, half-cell potentials were measured from test specimens; they all were below −200 mV; this indicated a 5% probability of corrosion. At introduction of 3% salt solution, the potential increased and remained at −500 mV for 4 months; this indicated 95% of corrosion. To remove chloride from test specimens, ECE was applied for 1.5 months. Afterward, average chloride content from the surface to 2 in. below the surface of test specimens with salt solution was significantly reduced from 10.68 lbs/cy to 4.12 lbs/cy, and half-cell potential decreased to below −200 mV. From limited laboratory test specimens, it can be concluded that the ECE method can effectively reduce corrosion activity by removing a significant amount of chloride.