Determination of migration efficiency of amino alcohol based migrating corrosion inhibitor through concrete

Abstract

The migration efficiency of an amino alcohol based migrating corrosion inhibitor (MCI) through hardened concrete of two different strengths (20 and 30 MPa) with two different thicknesses (25 and 40 mm) has been studied using diffusion test cell arrangement. The corrosion current I_corr was measured using Tafel extrapolation technique. There is a 20 times reduction in I_corr of steel in presence of MCI compared to that of bare steel. The migration efficiency decreases with an increase in thickness as well as strength of concrete. The density of concrete influences the diffusion rate of MCI. The diffusion rate is two times higher in 20 MPa concrete than that of 30 MPa concrete. The studies have indicated that the passive layer formed on the rebar surface is not stable in presence of 1% of chloride in 20 MPa concrete. Because of higher chloride threshold level the MCI has performed better in 30 MPa concrete. The results conclude that if higher protection efficiency is needed where structure is exposed to high chloride environments, it is more appropriate that the MCI shall be added at the rate of 2·45 kg m⁻³ along with concrete/repair mortar than applied on the concrete surface.