Decreasing Corrodibility of Steel Rebars in Carbonated Concrete Solution

Corrosion of steel rebars in reinforced concrete structure represents a major economic loss and a huge threat to people’s lives. Corrosion of reinforcement can occur due to ingress of acidic gases (CO2) in industrial areas or ingress of chloride in areas with marine atmospheres, into concrete pores. One of the most important methods utilized to decrease the corrosion of steel rebars is the use of inhibitors either with fresh concrete mixture or applied to concrete surface after hardening. This study focuses on the corrosion occurring due to carbonation in simulated concrete solution and investigates the effect of inhibitors on decreasing corrosion in carbonated concrete solution. In Simulated Concrete solution Ca(OH)2 with (pH=12), corrosion rate was 2.84 mpy due to formation of passive film on rebar’s surface. Due to carbonation of simulated concrete solution (pH= 8) resulting from ingress of CO2, corrosion rate increased to 11.67 mpy due to the dissolution of passive film. Adding 200 ppm of Polyethylene glycol, Quaternary Amine and ginger extract has decreased the corrodibility of steel rebars in carbonated simulated concrete solution (pH=8) from 11.67 mpy to 8, 3.75 and 1.13 mpy, respectively. X-Ray Diffraction (XRD) patterns showed the formation of passive films of iron oxides on rebar’s surface. As for Quaternary Amine, XRD have shown the formation of iron nitride besides iron oxides which provided higher protection from corrosion.