Study on the Corroded Hollow Section RC Columns Strengthened by ICCP-SS System

Abstract

In this paper, the behavior of corroded hollow section RC (reinforced concrete) columns strengthened by an Impressed Current Cathodic Protection and Structural Strengthening (ICCP-SS) system was investigated. The Carbon Fabric-Reinforced Cementitious Matrix (C-FRCM) composite serves dual functions in the intervention method. The axial compression behavior of strengthened columns was firstly investigated through axial compression tests. The influence of corrosion ratio and C-FRCM strengthening on the test results, such as failure mode, load–displacement curve, ultimate load, and ultimate strain, were analyzed. Test results showed that the ultimate load of the corroded specimens could be enhanced significantly by C-FRCM, and the ductility of the strengthened specimens was larger than the specimens without strengthening, especially for the specimens with higher corrosion ratios. Secondly, the effects of the ICCP-SS system on the migration and distribution laws of chloride ions (Cl−) in hollow section RC columns were analyzed by the potentiometric titration method. The main parameters include charging time, current density, and salt addition. Results showed that the rebar would have a certain blocking effect on the migration of Cl−, which resulted in that the content of Cl− in the inner side of the rebar was always larger than that of the outer side; and research results also showed that the increase of impressed current density and charge time would reduce the Cl− content on both sides of the rebar, while the impressed current would cause the Cl− near the rebars to constantly move toward the vicinity of CFRP.