Road salt
Road salt is material spread on roadways to lower water’s freezing point and limit ice formation. It is most commonly sodium chloride.
Freezing-point depression: The lowering of a liquid’s freezing point when another substance dissolves in it. Dissolved road salt lowers water’s freezing point, delaying ice formation.
Sodium chloride: An ionic compound, NaCl, commonly known as table salt or rock salt. It is the most widely used and generally least expensive road deicer.
Chloride pollution: The accumulation of chloride ions in the environment at concentrations that can harm ecosystems or water supplies. Road-salt runoff is a major source of chloride in many urban watersheds.
Sand for winter road maintenance: Abrasive material spread on roads to improve tire traction without melting ice. Sand improves grip mechanically, unlike salt’s chemical melting action.
Chloride source control: Measures that prevent chloride from entering water and soil at its source. Calibrated spreading and targeted treatment can reduce unnecessary road-salt losses.
Brine: A solution of salt in water. Salt commonly works after dissolving into a thin brine layer on pavement.
Calcium chloride: An ionic compound, CaCl₂, that dissolves exothermically and attracts water. It can work at lower temperatures than sodium chloride but costs more.
Freshwater salinization: The increase of dissolved salts in rivers, lakes, and groundwater. Repeated winter applications can raise salinity in nearby freshwater systems.
Calcium magnesium acetate: A chloride-free deicing compound made from calcium, magnesium, and acetate ions. It can reduce chloride-related corrosion, though it is more expensive than common salt.
Deicer alternatives: Materials and methods used instead of conventional chloride salts to manage ice on roads. Alternatives must be assessed for effectiveness, cost, corrosion, and ecological effects.