What exactly is deicing salt? This is a common question among consumers, followed by questions about the difference between deicing salt, road salt, and rock salt. These may be basic questions, but they lie at the heart of an important safety industry. Deicing salt is any product spread on the ground or a road surface to either remove or prevent the accumulation of ice. Road salt, the same material as deicing salt, is often applied in small amounts to some surfaces before ice or snow occur, in order to cause a layer of salt-water to more rapidly prevent snow and ice from “sticking.”
Deicing salt may refer to a variety of chemicals, but the best material is in rock salt form. Rock salt, when used as road salt on cement driving surfaces, is not as likely as more powdery minerals to be blown from the surface of the road, causing damage to surrounding soil. Road salt, is often purchased a year or two in advance by large carriers, in order to be prepared for extreme weather. This prevents the logistic catch-22 of ordering deicing salt in the midst of icy conditions. For areas where the temperature does not reach twenty degrees below freezing, simply layering the ground with road salt will cause ice and snow to melt.
Applying Deicing Salt
As long as plenty of rock salt, or deicing salt is available, the method of spreading the salt is secondary to the presence of a fresh supply. Roads are traditionally treated with snowplows and trucks which spread a combination of gravel and sodium chloride.
This is thought to be more cost effective than spreading deicing salt alone, but does not increase the capacity of the salt to lower the freezing point of the ice. There are all sorts of other chemicals which have been used recently to replace rock salt, but virtually all of these are several times more expensive than the rock salt itself.
The concern for deicing salt is that it may cause the corrosion of some metal surfaces. Mixing the salt with gravel and sand will serve to limit this effect. Because sodium chloride is much more widely available than alternatives, it remains the favorite deicing material for homes, businesses, and transit organizations alike.
So, deicing salt is usually sodium chloride, and is often mixed with sand and gravel for large scale road salt projects. For the home, the most important consideration is that road salt is safer than the garden variety salt, as it is less likely to blow into fertile areas of the lawn or garden. Other materials are available, but most of them are not cost effective for businesses or homes.