There are five main materials that are used as chemical de-icers:
calcium chloride, sodium chloride (table salt), potassium chloride, urea,
and calcium magnesium acetate.
Calcium chloride is the traditional ice-melting product. Though it will melt
ice to about -25 degrees F, it will form 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 F, 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 F.
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 rather 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 F.
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 they 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.
By: Ward Upham