Competitive role of inhibitive and aggressive ions in the corrosion of steel in concrete

摘要

The effect of various inhibitive ions (hydroxide, citrate, stannate) for the corrosion of steel in concrete was studied by weight loss measurements, chronopotential studies, anodic polarization technique and compressive strength tests. The salient features of the investigation were: in 100% OPC as well as in OPC + fly ash (3:1 ratio) extracts the passivity of steel was readily destroyed even by the presence of 10 000 ppm of chloride. However in 100% OPC and also in OPC + fly ash (3:1 ratio) extracts containing inhibitive and complexing agents like hydroxide, citrate and stannate, the passivity of steel was maintained even in the presence of 30 000 ppm of chloride. The addition of inhibitive ions like hydroxide, citrate and stannate not only decreased the corrosion rate of steel in simulated concrete environments but also increased the compressive strength of mortars. Citrates, stannates and CaO are effective inhibitors of the corrosion of steel in concrete. [References: 22]