Predicting long-term durability of steel reinforced concrete with calcium nitrite corrosion inhibitor

Steel reinforced concrete is one of the most durable and cost effective construction materials, but it can suffer in high chloride environments from corrosion due to chloride induced breakdown of the normal passive layer protecting the steel. One way of protecting embedded steel reinforcement from chloride induced corrosion is by the addition of corrosion inhibiting admixtures. The most widely used corrosion inhibiting admixture is calcium nitrite, due to its excellent inhibitor properties and its benign effect on concrete properties.One advantage to calcium nitrite is that its protection mechanism is well defined. In this paper data are presented that show the levels of chloride to which given levels of calcium nitrite will protect. Furthermore, it will be shown that once corrosion initiates, the rates are lower with calcium nitrite present. Finally, it is demonstrated how these results can be used by the design engineer in an integrated durability model to produce reinforced concrete structures with durabilities in excess of 50–100 years.