Sodium chloride is not used effectively when the temperature is below what?

Sodium chloride, commonly known as rock salt, is often used for de-icing roadways and pavements. However, its effectiveness diminishes significantly at lower temperatures. Below approximately -20° F, sodium chloride begins to lose its ability to lower the freezing point of water efficiently, leading to reduced melting performance on icy surfaces. At these frigid temperatures, the salt does not dissolve as readily into the ice, thus its ability to create a brine solution that can effectively melt ice is compromised.

This understanding is crucial for managing winter road safety and ensuring that appropriate measures are taken for ice control in severe cold conditions. Alternatives or supplementary de-icing materials may be needed in scenarios where temperatures drop below this threshold to maintain effective ice management.