Road Salt Use in Canada

The term “road salts” generally refers to the four common chloride salts used as deicers in Canada: sodium chloride (NaCl), calcium chloride (CaCl), magnesium chloride (MgCl) and potassium chloride (KCl), along with an anti-clumping agent, ferrocyanide salt.

Road salts work by lowering the freezing point of water. When snow or ice accumulates it forms a bond with the surface of a roadway or sidewalk. Road salts dissolve with the available water in snow or ice to form brine. The brine breaks the bond of ice or snow to the surface of the roadway by lowering the freezing temperature.

Road salts came into common use in the 1940’s as a melting agent for removing ice and snow. Driven by growing urbanization and increasing density of road networks, as well as changes in services levels requiring more “bare pavement” policies on roadways, total road salts usage and application rates have been on the rise in Canada since the 1970’s.

The federal government has estimated that almost 5 million tonnes of road salts were used on Canadian roadways in 1997/98 – approximately 165 kilograms of road salts per Canadian. Since that time, the total amount of road salts has continued to rise, with an estimated 6.8 million tonnes of road salts sold for highway deicing in Canada in 2003.

Sodium chloride is by far the most predominant road salt in use, with more than 4.7 million tonnes used in 1997/98. Quantities of the other types of road salts used during that period included 107,992 tonnes of calcium chloride, more than 25,000 tonnes of magnesium chloride and 2,000 tonnes of potassium chloride.