Re: What happens chemically when roads and sidewalks crack in the winter?

Nothing.

Cracking pavement is a physical change, caused by a combination of hard use, 
which makes small cracks, and the freezing of water. You see, water gets into 
the small cracks, then freezes. When water freezes, it expands. This makes 
small cracks into larger cracks.

Even in the absence of freezing temperatures, if you pound on concrete hard 
enough or long enough it will break.

Dan Berger
MadSci Administrator