Ice melters Source: North Carolina State Extension
There are five main materials that are used as chemical deicers: calcium chloride, sodium chloride (table salt), potassium chloride, urea, and calcium magnesium acetate. Calcium chloride is the traditional ice-melting product. Though it melts ice to about -25 degrees fahrenheit, it forms slippery, slimy surfaces on concrete and other hard surfaces. Plants are not likely to be harmed unless excessive amounts are used.
Rock salt is sodium chloride and is the least expensive material available. It is effective to approximately 12 degrees fahrenheit, but can damage soils, plants and metals.
Potassium chloride can also cause serious plant injury when washed or splashed on foliage. Both calcium chloride and potassium chloride can damage roots of plants.
Urea (carbonyl diamide) is a fertilizer that is sometimes used to melt ice. Though it is only about 10% as corrosive as sodium chloride, it can contaminate ground and surface water with nitrates. Urea is effective to about 21 degrees fahrenheit.
Calcium magnesium acetate (CMA), a newer product, is made from dolomitic limestone and acetic acid (the principal compound of vinegar). CMA works differently than the other materials in that it does not form a brine like salt, but helps prevent snow particles from sticking to each other or the road surface. It has little effect on plant growth or concrete surfaces. Performance decreases below 20 degrees fahrenheit.
Limited use of any of these products should cause little injury. Problems accumulate when they are used excessively and there is not adequate rainfall to wash or leach the material from the area. Since limited use is recommended it is best to remove the ice and snow by hand when possible.
When these products are applied, practice moderation. Resist the temptation to over apply just to make sure the ice and snow melts. Keep in mind this can damage concrete surfaces as well as the plants and grass growing along the walks and driveways. These problems are normally latent and do not show up until spring or summer.