ABSTRACT
Protective coating is considered to be one of the most economical and effective methods to protect steel from corrosion, as it can establish a physical barrier between the steel and the corrosive environment. In this study, silicate dioxide particle modified enamel (SDPME) coating is proposed for improved corrosion resistance and enhanced bond strength of steel bars in concrete structures. Plain steel bars with a diameter of 12 mm were used. Enamel slurry was made by mixing enamel frits with tap water, and silicate dioxide particle with an average size of 0.50 mm was added. The silicate dioxide particle is 10 wt.% of the enamel frits. The steel bars were dipped into the enamel slurry for 2 minutes and moved out, and then placed in a furnace at 800°C for 5 minutes, and finally cooled down to room temperature to produce SDPME-coated steel bars. The corrosion resistance of the SDPME-coated steel bar was tested by immersing in saturated calcium hydroxide solution containing 3.5 wt.% NaCl with open circuit potential, linear polarization resistance and electrochemical impedance spectroscopy. The bond strength was determined by using pull-out tests of SDPME-coated steel bar when embedded in concrete specimens. For comparison, both the corrosion resistance and bond strength of uncoated and pure enamel coated steel bars were also tested. Electrochemical corrosion results show that the corrosion resistance of SDPME-coated steel bar is ~300 times higher than that of the uncoated one. Pull-out tests demonstrate that the bond strength of SDPME-coated steel bar is 3.63 times greater than that of the uncoated steel bar. Therefore, SDPME coating increases both the corrosion resistance and the bond strength of steel bar.
