Comparison of corrosion products formed on black and corrosion resistant steel reinforcement embedded in cement paste

摘要

Present research compares morphology and composition of corrosion products formed during accelerated corrosion of black and corrosion resistant steel embedded in ordinary cement paste. For this purpose, cement paste samples with different types of embedded steel were cast and cured. After curing, samples were placed in to 3.5% NaCI solution to simulate marine environment exposure. During this period samples were kept under constant potential of 500 mV vs SCE. When a significant increase in current was reached, samples were removed from the solution. The formed corrosion products in the steel/cement paste interface were investigated through scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX) and x-ray diffraction (XRD). Analysis of corrosion products showed that depending on the chemical composition of the reinforcing steel, different corrosion products were formed around different types of steel. Morphology and chemical composition of the corrosion products changed with the amount of Cr present in the steel. The findings on the corrosion products were also compared to resistances obtained by long-term monitoring using electrochemical impedance spectroscopy (EIS). Based on these results, a pattern of formation of corrosion products during corrosion of stainless steel in concrete was proposed.