Electrochemical investigation of the influence of a durable exterior emulsion coating on the corrosion resistance of mild steel in simulated concrete pore solution

In concrete technology, rebars are used to strengthen the structure of concrete.The corrosion resistance of mild steel rebars in simulated concrete pore solution has be evaluated by electrochemical studies such as polarization study and AC impedance spectroscopy.The mild steel rebars have been coated with Nippon paint, SUMO XTRA, Durable exterior emulsion.Corrosion parameters such as linear polarization resistance (LPR), corrosion current density, corrosion potential, Tafel slopes, charge transfer resistance (Rt), double layer capacitance (Cdl), phase angle and impedance value have been derived from electrochemical studies.In the presence of emulsion coating, it was observed that, LPR increases, corrosion current density decreases, Rt increases, Cdl decreases, phase angle increases and impedance value increases.When Durable exterior emulsion coated mild steel was immersed in simulated concrete pore solution, the LPR value increases from 283 Ohm•cm 2 to 1.37×10 5 Ohm•cm 2 ; the corrosion current density decreases from 1.50 ×10 -4 A/cm 2 to 3.323×10 -7 A/cm 2 ; charge transfer resistance increases from 50.25 Ohm•cm 2 to 64351 Ohm•cm 2 ; double layer capacitance decreases from 1.01×10 -7 F/cm 2 to 7.93×10 -11 F/cm 2 ; the impedance increases from 1.81 [log(Z/Ohm)] to 4.82 [log(Z/Ohm)] and the phase angle increases from 36.27° to 51.54°.These observations confirm that the emulsion coating is stable in the presence of simulated concrete pore solution.This has controlled the corrosion of the rebars in the concrete.There will be augment in the life time of the mild steel rebars.The corrosion inhibition efficiency calculated from electrochemical studies is greater than 99%.