Identification on acidification damage of external anode system induced by impressed current cathodic protection for reinforced concrete.

Abstract

Impressed current cathodic protection (ICCP) was widely applied for the corrosion control of reinforced concrete. During the ICCP treatment, the anodic reactions happened on the primary anode surface may induce acidification and subsequently pH drop in the vicinity of the anode, leading to damage of the external anode mortar. In this study, the relationship between the applied current (simulating ICCP treatment) on the Ti mesh anode and pH alterations in simulated concrete pore (SCP) solution (with/without chlorides) was investigated. It was found that the applied current slightly reduced the corrosion resistance of Ti mesh; this negative effect was more pronounced in the presence of chlorides. The pH value of SCP solution near Ti mesh anode decreased when the external current was applied. The consumption rate of OH- ion was higher in the chloride-containing SCP solution. A mathematical model was proposed between the electric charge quantity (Q) and OH- concentration (cOH-) in SCP solution near Ti mesh anode. This model is a useful tool to quantitatively identify the acidification damage induced by impressed current from the perspective of pH alternation near Ti mesh anode.