How do I Choose the Best Deicing Salt?

Dave Slovak

Winter months typically bring cold temperatures, snow, and ice. As a result, people brave the elements to shovel snow and remove ice to have a clear driveway and safe sidewalks. Many people spread deicing salt to melt ice or to prevent it from forming. People can choose from four main types of deicing salts: sodium chloride, also known as rock salt, calcium chloride, potassium chloride and magnesium chloride. When choosing the best deicing salt, you should weigh the pros and cons of each salt’s costs, applicable temperature, and effects on the environment.

Salt is used to combat icy roadway conditions.
Salt is used to combat icy roadway conditions.

Sodium chloride, also known as rock salt, is the most commonly-used deicing salt because it is widely available and the cheapest of the deicing salts. Additional benefits of rock salt are that it is easy to apply and will not damage concrete. The downside, however, is that rock salt will not melt ice when the temperature falls below 15 degrees Fahrenheit (-9 degrees Celsius). In addition, rock salt can be corrosive to metals and can damage grass and trees. When rock salt dissolves, it releases a great number of chloride ions, which can contribute to pollution in streams, rivers, and lakes.

Calcium chloride can melt ice at -25 degrees Fahrenheit.
Calcium chloride can melt ice at -25 degrees Fahrenheit.

Potassium chloride, perhaps best known for its role in the production of fertilizer, can also be used as a deicing salt. This salt does not usually harm vegetation when used properly, and it does not irritate the skin as other deicing salts can. Like rock salt, however, potassium chloride is only effective when the temperature is above 15 degrees Fahrenheit (-9 degrees Celsius) but at twice the cost. Potassium chloride is typically combined with other chemicals to melt ice at lower temperatures. It also can pollute the groundwater with the chlorine it releases.

Calcium chloride is more expensive than rock salt, but this salt is a popular option in colder climates. Calcium chloride produces an exothermic reaction, so it can melt snow and ice at -25 degrees Fahrenheit (-32 degrees Celsius). This salt is safer to use around vegetation, but it can irritate moist skin. Another drawback is that a high concentration calcium chloride can damage concrete. It carries environmental risks similar to those of the other salts.

Magnesium chloride is very similar to calcium chloride. Magnesium chloride can melt snow and ice at -15 degrees Fahrenheit (-26 degrees Celsius) and produces the least amount of chlorine of the common deicing salts, although it still poses a pollution risk to nearby water supplies. When compared to calcium chloride, it is considered less corrosive and less damaging to vegetation, but these benefits come at a higher financial cost.

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Discussion Comments


Pointing out the corrosive nature of salt brings up a good point -- here in the beautiful South, we don't have as much of a problem with the bottoms of our cars rusting out as folks in the north do. That's because winters are milder in these parts so we don't have the problem of rock salt being on the ground for long periods of time.

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