How do you melt ice/snow when the temperature is under 5F (-15C)

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I live in the mid-atlantic region in USA, where we get the regular change of seasons, and our winters are frequently around 30F (-1C). When it snows, we use rock salt to melt the ice on the sidewalks and roads. However, most rock salt that you would buy at Home Depot/Lowe’s says it works on temperatures as low as 5F (-15C).

So I must beg the question: In areas such as the Great Lakes region or Canada, where winters frequently are below this 5F (-15C) threshold, what do you use to melt the ice if rock salt doesn’t work at these temperatures?

In: Chemistry
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You use something like calcium chloride, which works down to -25F, or magnesium chloride, which works down to 0F. There are also some preventative treatments that help prevent ice from forming in the first place, instead of working to melt it after the fact.

In general, no. If you want to remove ice you have to do it before it becomes that cold or by scraping it away while it is frozen. But this is not as big of an issue as you might imagine. Ice is a bigger problem at around the freezing temperature and the colder it gets the less of a problem it is. Firstly ice needs to be flowing water to form. If it is too cold then it will form snow crystals and not ice. Snow is not as slippery as ice and can also be easily plowed away. The only problem with snow is that if you compress it then it will turn into ice because small sections of it can melt at once due to the pressure. But this is something which happens over time and is also slower the colder it gets. A second reason is that when ice is very cold it becomes much more solid then at higher tempeatures. It becomes having properties more associated with steel then with soap. So if the ice have a rough finish, which it often have when people drive on it with snow ploughs and studded tyres, it will keep its rough finish for longer and not form the smooth slippery finish you might associate with ice. So the colder it gets the more traction you would expect on ice.

In some locations you just don’t, it becomes counter productive to try instead you deal with the conditions.

Mostly in Canada when it gets below a temperature where sales is effective, they switch to sand and gravel after lowing the roads. This provides traction, and is cleaned in the spring by road sweepers.