When the temperatures drop and roads get icy, de-icing a sidewalk is a great way to reduce your risk of injury.
Five chemicals are usually associated with de-icers. While sometimes used alone, these chemicals are often combined with each other or with other materials in order to improve overall performance, reduce costs, and prevent damage to plants, ground water, or concrete.
Calcium chloride (CaCl2) is available in several forms: flake, pellet, or liquid. This chemical out-performs most other de-icing agents, especially in lower temperatures. As it works, calcium chloride releases heat because it produces an exothermic reaction.
Sodium chloride (NaCl), also known as rock salt, began being used as a de-icer in the 1940s. This is an effective de-icer for areas that receive a lot of road traffic because it draws heat from the environment instead of creating it itself through exothermic reactions. Rock salt works best when temperatures are below 25 degrees Fahrenheit.
Potassium chloride (KCl) occurs naturally and is used, besides as a de-icer, in fertilizer and as a substitute for food salt. Potassium chloride is not used widely, however, because of its potential to damage foliage and inhibit rooting.
Urea (NH2CONH2) is a synthesization of ammonia and carbon dioxide (CO2). Though it is most often used as a fertilizer, it is used in de-icers more frequently than potassium chloride because it has a lower potential to burn plants.
Calcium magnesium acetate (CMA) is a relatively new chemical agent that works without salt. It is made from a combination of acetic acid and dolomitic limestone. CMA causes little damage to concrete or plants, and is used as an alternative to salt varieties in environmentally sensitive areas.
Depending on the type of de-icer you choose to use, you should look for certain features. Uniformly shaped, spherical pellets penetrate ice fastest and more efficiently than any other shapes. Flake forms perform worse than any other form because they melt horizontally and vertically, making them too diluted by the time they reach the pavement, thus rendering them ineffective at undercutting and disbonding ice.
Calcium chloride and calcium magnesium acetate cause the least amount of damage to concrete and metal. Calcium magnesium acetate is the safest for plants. Calcium chloride is the only effective de-icing agent in extreme cold; for example, sodium chloride is most effective around 15 degrees Fahrenheit, but calcium chloride works to temperatures around -20 degree Fahrenheit.