الفهرس 
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Abstract
Corrosion of steel rebars in reinforced concrete structure is considered a major economic loss besides seriously threatening inhabitants’ lives. Corrosion of steel reinforcement mainly occurs due to the ingression of acidic species such as (CO2) gas, in industrial zones or ingression of chlorides in regions of marine atmosphere, through the concrete pores. The use of corrosion inhibitors is one of the most important methods applied to decrease the corrodibility of steel rebars either with freshly prepared concrete mix or applied to concrete surface after being hardened.
We studied decreasing the corrodibility of steel rebars in the simulated carbonated concrete pore solutions besides simulated concrete pore solutions containing 3.5 wt.% NaCl. We used three safe and environmentally friendly organic compounds: Polyethylene glycol, Quaternary Amine and Ginger Extract which is considered also as a green inhibitor.
In Simulated Concrete pore solution “Calcium Hydroxide” Ca(OH)2 with a (pH=12), potentio-dynamic polarization tests revealed that corrosion rate was 2.84 mpy owing to the formation of a protective passive film on rebar’s surface. Due to carbonation of simulated concrete pore solution (pH= 8) caused by the ingression of CO2, corrosion rate increased to 11.67 mpy because of the dissolution of the passive film. The addition of 200 ppm of Polyethylene glycol, Quaternary Amine and ginger extract has declined the corrosion rate of steel rebars in simulated carbonated concrete pore solution (pH=8) from 11.67 mpy to 8, 3.75 and 1.13 mpy, respectively.
In Simulated Concrete pore solution Ca(OH)2 containing 3.5 wt.% NaCl, Addition 200 ppm of Polyethylene glycol, Quaternary Amine and ginger extract has declined the corrosion rate of steel rebars from 13.78 mpy to 8.82, 4.82 & 1.93 mpy, respectively.
Scanning Electron Microscopy (SEM) showed the rough, damaged corroded rebar surface in case of carbonated solution with pH=8 and smoother surface topography when adding inhibitors. Energy Dispersive Spectroscopy (EDS) assessment showed the presence of oxygen which can explain the formation of protective iron oxide / hydroxide layer on steel surface. Also, the presence of Carbon indicated the formation of carbonaceous organic film on steel surface via physical adsorption. In case of Quaternary Amine, the presence of nitrogen indicated the formation of protective iron nitride on steel surface.
X-Ray Diffraction (XRD) patterns revealed the formation of protective passive layers of iron oxides on steel rebar’s surface. Regarding Quaternary Amine, XRD has emphasized the formation of iron nitride in addition to iron oxides which provided higher protection against corrosion.