Question

How does putting salt on frozen roads make the roads less icy?

Answer 1

Hi, Sulikjon!
The main purpose it to lower the freezing point of water, and we use salt for this. 
I hope this helps;)

Answer 2

Icy sidewalks and roadways can lead to disasters. Wintertime slick surfaces can cause a variety of problems, from a simple slip to a major car accident. To prevent property damage, injury or death, it's important for surfaces to be de-iced. This is usually done by distributing sand, chemical de-icers or salt over the ice. Of these three, salt is the most common.

Hope this helps.