What is the difference between rock salt, calcium chloride and magnesium chloride?
Rock salt is the cheapest and melts the most ice, but works best on pavement above about 15°F. Calcium chloride and magnesium chloride keep working much colder, to about -20°F and -10°F in Minnesota's Smart Salting guidance, and cost more.
Calcium and magnesium chloride can leave a slick surface if over-applied, so they are used where and when they are needed rather than across a whole lot. Blends and treated salt sit in between.
Pavement temperature, not the air temperature in the forecast, decides which one is right on a given morning.
Go deeper
Sources
- Minnesota Pollution Control Agency, Smart Salting for Roads Manual (2023)
- Minnesota Stormwater Manual: how salt works and deicing chemicals
More on salt & ice
- At what temperature does rock salt stop working?
- Why is my parking lot icy even though it was salted?
- Why did my contractor salt when it didn't snow?
- What is pre-treatment or brine, and is it worth it?
- Is sand better than salt for ice?
- Does salt damage concrete sidewalks?
- What ice melt is safe for pavers and natural stone?
- Is ice melt safe for pets and landscaping?
- Do I have to buy plowing to get salting and de-icing?
From JRW Services LLC, commercial snow and ice management across Sussex, Passaic, Bergen, Morris and Warren counties, NJ. All answers
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