Laboratory Testing and Field Evaluation of Electrochemical Chloride Extraction Method to Reduce Corrosion in Rebar Embedded in Concrete
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, two reinforced slabs and 12 reinforced beams were prepared, cracked, and saturated with salt solution for four months, followed by ECE application. Initially, half-cell potentials were measured from test specimens; they all were below -200 mV; this indicated a five percent probability of corrosion. At introduction of three percent salt solution, the potential increased and remained at -500 mV for four months; this indicated 95 percent of corrosion. To remove chloride from test specimens, ECE was applied for 1.5 months. Afterward, average chloride content from the surface to two inches 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.