What Temperature Does Road Salt Not Work?

October 10, 2023

When it comes to winter weather, salting the roads is a tried and true method of melting snow and ice and keeping traffic moving. But it's not immune to extreme temperatures and conditions.

The most common road treatment is plain old road salt-sodium chloride, the same stuff you'd sprinkle on your dinner plate. It works well enough when the temperature is above freezing and the sun is out, but as the temperature drops, it starts to lose its effectiveness. This is when other chemicals are used to help with the de-icing process.

Other chemical solutions like calcium magnesium acetate, potassium acetate, potassium chloride some brines, and even beet juice are combined with the standard road salt to increase its effectiveness at lower temperatures. These other chemicals work by lowering the freezing point of water and making it more difficult for ice and snow to form on top of the road surface.

Another reason that some salt alternatives are being used is because plain road salt can be rough on cars and concrete driveways and it's also bad for the environment as it speeds up rusting of vehicles, kills plants, and turns freshwater streams and ponds into saline lakes. The good news is that there are new technologies that can encapsulate the salt particle with a premium chloride liquid like calcium or magnesium, and synergize it to improve its performance at colder temperatures. This is the way that many of these new products work, and they're already being used to some degree in places like Canada, where they have seen positive results.


Traffic Dave is on a mission to help traffic engineers, transportation planners, and other transportation professionals improve our world.
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