Determining effect of cementitious repair materials on embedded steel reinforcement exposed to chloride environment using electrochemical NDT methods




Rodulfo Gomez, Perla

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For many years, Reinforced Concrete has been used to construct buildings all around the globe. Corrosion-affected RC structures may lose durability, possibly reducing life expectancy or failing catastrophically if timely action is not taken. Critical content of chloride accumulated at the rebar-concrete interface may break the protective passive film of the rebar surface by the diffusion of chloride through the concrete cover. Specialized cementitious repair materials can be used to restore and extend the service life of RC structures that have been exposed and damaged due to corrosion caused by a marine environment. This research evaluated three different types of cementitious repair materials and a control mix. Electrochemical NDT techniques: Half-Cell Potential (HCP), Macrocell current and Linear Polarization Resistance (LPR) were used in this study to measure and monitor corrosion potential, current passed and the corrosion current on the three types of cementitious repair materials and control under examination throughout the duration of the research. The effectiveness of repair materials assessed in this study when monitoring the corrosion potential, current passed and corrosion current, when exposed to a chloride environment was compared to that of regular concrete using Ordinary Portland Cement. From the Electrochemical NDT results, it was found that Mix F outperformed Mix M, Mix P and control when exposed to a chloride environment. Further examination of the three different repair cementitious materials was done through Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDX) analysis. Through the EDX microscopy analysis, it was found that Mix F cementitious repair material was the one showing the least amount of chloride per % atomic weight of sample compared to Mixes P, M and Control. As a result, Mix F was the most effective in delaying or retarding the transport of chloride ions reaching the rebar through the concrete matrix and initiating the corrosion process. Furthermore, observation of all the repair materials through SEM showed that the Mix F repairs have the densest microstructure. The results obtained in this study helped in the determination of the best cementitious repair material for the inhibition of corrosion of RC structures in contact with marine environments.



Half Cell Potential, Linear Polarization Resistance, Macrocell Current, Electrical Conductivity, Corrosion repair, Correlation analysis