A Corrosion Inhibitor Formulated with Calcium Nitrite for Use in Reinforced Concrete

Abstract

The scarcity of good aggregate in Japan led to an investigation of the use of a corrosion inhibitor for reinforced concrete. Corrosion current measured on small test specimens soaked in limewater for one day with an impressed voltage of + 400 mV with respect to the saturated calomel electrode shows that the introduction of calcium nitrite diminishes the corrosion of reinforcing steel in the presence of admixed sodium chloride. Long-term tests on larger specimens partially immersed in saturated sodium chloride solution indicate that admixed calcium nitrite can prevent the open circuit potential of reinforcing steel from entering the active region. Calcium nitrite was found to enhance the strength of concrete. Calcium nitrite complies with the requirements of ASTM Specification for Chemical Admixtures for Concrete (C 494-71). The use of a calcium-based admixture is expected to sidestep the issue of alkali-aggregate reactions and subsequent deterioration of concrete.

Effects of chloride and chloride-free accelerators combined with typical admixtures on the early-age cracking risk of concrete repair slabs

“…Calcium nitrite has been a very popular chloride-free accelerator since patented in 1969 [16]. Calcium nitrites have been shown to be a very effective form of protection from corrosion [16][17][18][19] and have shown strength developments comparable to calcium chloride [20]. Sodium thiocyanate is a hardening accelerator.…”

Ensayos de laboratorio sobre el efecto inhibidor de los NO₂^- sobre la corrosión de las armaduras

“…Los resultados de estas dos últimas propiedades ensayadas con diferentes tipos de cemento se muestran en la figura 3 (21). El efecto sobre las resistencias mecánicas hasta un año pudo apreciarse que fue muy ligero.…”

Anion capture and exchange by functional coatings: New routes to mitigate steel corrosion in concrete infrastructure

“…The presence of NO 3 − and NO 2 − anions in the pore solution can counteract the corrosive actions of Cl − ions [12–17]. These species mitigate corrosion processes by oxidizing Fe 2+ species to Fe 3+ ions, which precipitate and re-form passivating films [7,18].…”