Efficacies of sodium nitrite and sodium citrate–zinc acetate mixture to inhibit steel rebar corrosion in simulated concrete interstitial solution contaminated with NaCl

Abstract

Investigations were carried out to compare the effectiveness of compounds such as sodium nitrite, trisodium citrate (TSC) and TSC–zinc acetate to inhibit the corrosion of steel rebar in simulated concrete interstitial solution contaminated with chloride and to explain the mechanism of corrosion inhibition on reinforcing steel by these systems. Inhibition efficiency of these systems was studied by electrochemical techniques such as potentiodynamic polarization and half cell potential measurements. Electronic spectral studies of simulated pore solution and FT-IR spectral investigations of the film deposited on steel surface were carried out for understanding the mechanism of corrosion inhibition. Microscopic surface analysis was conducted to obtain the surface morphological behaviour of steel rebar. TSC alone was not exhibited good corrosion inhibition at very low and high concentrations according to electrochemical studies. However, in the presence of zinc acetate, corrosion protection efficiency of TSC increased appreciably. When comparing with sodium nitrite, TSC in the presence and absence of zinc acetate displayed good corrosion inhibition efficiency. Among a number of samples, TSC 100 ppm-zinc acetate 50 ppm combination showed maximum corrosion inhibition efficiency on steel rebar in simulated concrete interstitial solution.