One is by reacting hydrated lime with NOX gas, which typically comes from a nitric acid plant.

[5] Nitrite's success as a corrosion inhibitor for the protection of embedded steel in reinforced concrete comes from the "smart" behavior of the AFm phase (AFm is shorthand for a family of hydrated calcium aluminate hydrate phases: aluminate-ferrite-monosubstituent phases); normally it stores nitrite in preference to sulfate, carbonate, and hydroxyl ions so that the nitrite concentrations of pore fluid are low.

However, if chloride ingress occurs in service (from sea water or de-icing salt), the AFm undergoes ion exchange, gaining chloride and forming Friedel's salt (Cl-AFm), while releasing soluble nitrite ions to the pore fluid.

[6] The corrosion inhibition mechanism of nitrite in concrete is twofold: on one hand, the concentration of the very corrosive chloride anions (responsible for the pitting corrosion of steel rebars) in the concrete pore water decreases after their uptake into the AFm phases and on the other hand, nitrites also oxidize the Fe2+ ions present around the corroding rebars leading to the precipitation of poorly soluble iron oxy-hydroxides onto the steel surface contributing to its passivation.

Calcium nitrite is widely used in concrete for high-rise construction, highways, bridges, railroads, airports, and large-scale hydraulics.

It can substitute for sodium nitrite, a product often used as a heat transfer fluid in thermal energy storage units for large air-conditioning or process cooling applications.