Electrochemical and microstructural analysis of reinforcement corrosion in concretes exposed to cyclic chloride-carbonation conditions

Abstract

The current study evaluated the corrosion behaviour of fly ash-based Portland pozzolanic cement (PC) concrete compared to conventional ordinary Portland cement (OC) concrete under cyclic chloride and carbonation exposure. Corrosion monitoring was done on reinforced concrete cube samples using three methods: half-cell potential, linear polarisation resistance, and electrochemical impedance spectroscopy. In addition, carbonation depth and chloride ion penetration profiles were measured on 100 mm concrete cubes to establish the most critical component impacting corrosion formation. After the testing time, the concrete surface and the removed steel bars were examined under a microscope to check how much and what type of corrosion damage they had. The study examines how well PC and OC concretes work in harsh environmental conditions. The outcomes revealed that although the chloride ions diffuse faster, carbonation plays a vital role in pushing the chlorides toward deeper depth, increasing the risk of pitting corrosion. Corrosion was initiated after 10 cyclic exposures in both concrete types. PC concrete was more vulnerable, with higher corrosion rates than OC. The surface cracks on PC concrete at the end of the testing were more significant than those in OC, signifying the severity of corrosion.