In Situ Monitoring of Anodic Acidification Process Using 3D μ-XCT Method

Debonding of the primary anode caused by anodic acidification is one of the major failure modes of the impressed current cathodic protection (ICCP) system in reinforced concrete structures. This study used 3D micro X-ray computed tomography (μ-XCT) to monitor the in situ evolution of the anodic acidification-affected zone. Samples were scanned after 0 to 40 days of the accelerated anodic acidification test. The anodic acidification-affected zone was identified in μ-XCT images using the gray level segmentation method. The total volume of this zone was measured using the 3D reconstruction method. It was found that detailed 3D information can be extracted using the 3D reconstruction method. The spatial heterogeneity was analyzed using this reconstructed volume information. The Faraday efficiency was calculated and found to increase after 20 days of operation. It was also found that the affected zone was proportional to the input electrical energy. The proposed model is useful for estimating the durability of an ICCP system.