48 / 2022-03-29 19:49:25

Quartz sand modified enamel coating for enhanced corrosion resistance of steel rebar

Reinforcement steel corrosion,,Enamel coating,,Microstructural characterization,electrochemical impedance spectroscopy;,linear polarization resistance

Chloride-induced reinforcement steel corrosion is one of the main causes of premature deterioration of reinforced concrete (RC) structures in marine environment or in cold regions subjected to the use of deicing salts. Corrosion causes concrete cracking, bond loss between steel and concrete, mechanical degradation of reinforcement steel, and reduction in carrying capacity of structural components and systems. Therefore, it is of paramount importance to develop some methods or technique to prevent or mitigate steel rebar corrosion. In this study, quartz sand modified enamel coating is developed for enhanced corrosion resistance of steel reinforcement in RC structures. Quartz sand (~0.50 mm diameter), tap water and enamel powder were first mixed together to make enamel slurry, and then cleaned steel rebars were immersed in the enamel slurry. The wet enamel coated steel rebars were moved into a furnace for firing 10 minutes at 840 °C, and finally cooled down to form quartz sand modified enamel coated steel rebars. The microstructure of the quartz sand modified enamel coating including the thickness and the porosity was examined with an optical microscopy. The corrosion performance of the quartz sand modified enamel coated steel rebars was evaluated by immersion tests in 3.5 wt.% NaCl solution with open circuit potential, linear polarization resistance and electrochemical impedance spectroscopy. Uncoated steel rebars were also tested for comparison. Results show that quartz sand modified enamel coating has an average thickness of around 300 µm with isolated air bubbles. The corrosion resistance of quartz sand modified enamel coated steel rebars is significantly higher than uncoated steel rebars.