An ascorbic benzoate (AB) was synthesized and its inhibitive activity towards steel rebar corrosion in 3.5% NaCl saturated Ca(OH)₂ solution was investigated by corrosion electrochemical and surface analysis techniques. Together with the quantum chemical calculations and molecular dynamics simulation (MD), the adsorption behavior at the Fe surface and the inhibition mechanism of the compound were discussed. The results indicate that the addition of AB can effectively decrease the corrosion current density of steel rebar and enhance its corrosion resistance suggesting that the Cl^－ induced corrosion of steel rebar is strongly retarded by the inhibitor, which acts as a cathodic type inhibitor. A protective film can be formed on steel rebar surfaces via the adsorption and the formation of insoluble complex with iron ions, hence blocking the Cl^－ access to the metal surface, and the adsorption on Fe surface obeys to the Langmuir adsorption isotherm. The theoretical calculations and MD show that the moieties of lactone and benzene rings in the molecules are the preferred active sites for the electrophilic attack, also for the nucleophilic attack, and thereby the inhibitor molecules can easily adsorb onto metal surface through the sharing of electrons with iron atoms in the parallel mode to the Fe surface.

Key words: steel rebar corrosion, corrosion inhibitor, inhibition mechanism, quantum chemical calculation, molecular dynamic simulation