The efficiency of nitrite ions as inhibitors of steel corrosion in carbonated pore simulating solutions

M.B. VALCARCE; M. VÁZQUEZ

Banff, Canada

Congreso; 58th Annual meeting of the international society of electrochemistry (ISE); 2007

International society of electrochemistry

The efficiency of nitrite ions as inhibitors of steel corrosion in carbonated pore simulating solutions M. B. Valcarce and M. Vazquez *  División Corrosión, INTEMA, Facultad de Ingeniería, Universidad Nacional de Mar del Plata J. B. Justo 4302 B7608FDQ  Mar del Plata, ARGENTINA *mvazquez@fi.mdp.edu.ar Nitrite ions are well-known corrosion inhibitors of steel corrosion in concrete. However, in marine environments, the presence of chloride ions can decrease the inhibitor efficiency.  Also, the level of protection provided depends on the ratio between chloride and hydroxyl concentrations. This work is focused on investigating the case of a carbonated (low pH) and contaminated concrete (high chloride concentration). Various inhibitor dosages, together with various chloride contents are tested in simulated pore solution. The inhibition efficiency is evaluated on steel electrodes, measuring electrochemical parameters such as corrosion potential, corrosion current density and polarization resistance, weight loss and performing electrochemical impedance spectra. The results are compared to those obtained for highly passivating solutions (pH 13.9), where the electrochemical tests show no difference in behaviour when using chloride contaminated solutions where the ratio [Cl-]/[OH-] is lower than 1. The presence of chloride induced pitting and the inhibitor was able to prevent pitting only when nitrite/chloride ratio was 0.25.