Irregularly shaped particles tend to melt randomly in all directions. Flakes melt as much horizontally as they do vertically. There are five chemicals commonly used as deicers. While they can be used alone, they often are blended together or combined with other materials to enhance their performance. Calcium chloride Available in flakes, pellets or liquid.
Calcium chloride produces an exothermic reaction, giving off heat.
Because of this, it often performs better than many other deicing salts, especially at lower temperatures. Some highway departments spray liquid calcium chloride over rock salt to lower its melting temperature. Sodium chloride Rock salt first was used as a road deicer in the 1940s. An estimated 10 to 14 million tons will be used yearly on roads in the United States and Canada. Sodium chloride is relatively inexpensive, but it can burn plants and corrode metal and concrete.