What is the primary reason for using calcium nitrate in concrete?

Using calcium nitrate in concrete is primarily for its ability to inhibit rusting of reinforcement steel, which is crucial for the longevity and durability of reinforced concrete structures. When embedded steel reinforcement experiences moisture and oxygen, it can corrode, leading to structural integrity issues over time. Calcium nitrate acts as a corrosion inhibitor by providing a protective layer on the steel surface and adjusting the pH level of the pore solution in concrete, which helps reduce the onset of corrosion.

This property makes calcium nitrate particularly useful in areas where concrete may be exposed to aggressive environments, such as coastal regions or de-iced roadways, where chloride ions can accelerate rusting. By using calcium nitrate, engineers can enhance the lifespan of concrete structures, ultimately contributing to safer and more sustainable construction practices.

Other agents like workability enhancers, heat of hydration reducers, and curing property enhancers serve different functions in the concrete mix but do not directly address the corrosion issue that calcium nitrate specifically targets.