This article about salting roads is republished here with permission from The Conversation. This content is shared here because the topic may interest Snopes readers; it does not, however, represent the work of Snopes fact-checkers or editors.
Brrr … it’s cold out there! Children are flocking to the television in hopes of hearing there will be a snow day; the bread and milk aisles at grocery stores are empty because of an impending snow storm; and utility trucks are out spraying salt or salt water on the roads.
We all know why the first two happen – kids are excited for a day off of school filled with hot chocolate and snowmen. Adults are stocking up on necessities. But what’s up with those trucks?
Salt that’s dumped on top of ice relies on the sun or the friction of car tires driving over it to initially melt the ice to a slush that can mix with the salt and then won’t refreeze. Pre-treating with solid salt relies on the warmer road surface to initially melt any snow or freezing rain so that it can properly mix with the salt. This is also why pre-treatment of bridges – which are colder than other roads – does not typically work, and why you see “bridge freezes before road” signs.
These salt solutions decrease the freezing temperature of water to around 15 F. So, unfortunately for folks facing truly frigid temps, treating with salt won’t get rid of ice on their roads.
An alternative strategy used at these lower temperatures is putting sand on the ice. Sand doesn’t change the melting temperature, it just provides a rough surface for your tires to prevent slipping and sliding.
The science of freezing point depression can be applied to any solution, and many research groups have focused on developing alternatives with fewer negative environmental consequences. They include additives such as molasses and beet juice. So maybe you can look forward to cleaning not just white salt off the bottom of your jeans after a winter walk, but pink salt as well.