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In order to research the effect of viscosity modifying admixture (VMA) on the rebar rust resistance in self-compacting concrete, stereoscopic microscope, linear polarization, electrochemical impedance spectroscopy and Tafel polarization test method were utilized to study the effect of three commonly used viscosity modifying admixtures, polyacrylamide (PAM), hydroxypropyl methyl cellulose (HPMC) and hydroxyethyl cellulose (HEC) on the rebar rust resistance performance in simulated concrete pore solution. Results showed that PAM, HPMC and HEC could effectively inhibit the corrosion of rebar in simulated concrete pore solution. With the content of VMAs increasing, the corrosion resistance of rebar was enhanced. The rust resistance ability of the three VMAs on rebar increased in the following order: HEC< HPMC< PAM. Furthermore, the inhibition effect of PAM, HPMC and HEC on the cathodic corrosion process of rebar was stronger than that of the anodic process. Among them, PAM and HPMC were cathode type rust inhibitors, while HEC was a mixed type rust inhibitor that mainly suppressed the cathode.