Defrosting is defined as the removal of existing snow, ice or frost from a road, airport runway, or other surface. It includes both mechanical tools such as plowing or scraping, and chemical tools such as the application of salt or other de-icing chemicals. Anti-icing is the treatment with chemicals that melt ice before or during the onset of a storm to prevent or delay the formation of ice and snow and its adhesion to the surface. Saltwater or soaked salt is usually applied shortly before a blizzard begins. When properly applied, anti-icing can significantly reduce the amount of salt required and allow for easier removal by mechanical methods including farming. [one]

Road defrosting has historically been accomplished by snow plows or specially designed dump trucks that spread salt, often mixed with sand and gravel, onto slippery roads. Rock salt is normally used because it is inexpensive and readily available in large quantities. However, brine freezes at -18 ° C (0 ° F) and is therefore ineffective at these low temperatures. In addition, steel used in most vehicles and rebar in concrete bridges have a high tendency to cause rust and corrosion. Newer snow melers use other salts such as calcium chloride and magnesium chloride, which not only lower the freezing point of water to a much lower temperature [2], but also produce an exothermic reaction whose radiated heat further aids melting. In addition, they are a bit safer for concrete pavements, but the excess should still be removed.