Interesting factoids about salt and ice.

It's very common for people to think salt is put down on the roads during a snowstorm because salt melts ice. Well, technically speaking, that isn't true. Salt does not melt ice. Salt creates a freezing point depression. That means a mixture of salt and water lowers (depresses) the freezing point of water from 32 degrees to 25 degrees.

The freezing point depression only works up to a certain point. At temperatures below 10 degrees salt becomes useless and the roads are treated with chemicals. Most chemical liquid sprays contain either magnesium chloride, calcium chloride, potassium chloride and sodium chloride. And then there's "produced brine" which has some controversy attached to it. 

Road De-Icing Fluids May Contain Unhealthy Chemicals