Recent snow and the condition of the roads

[xud]

Maybe it's me but I can't help thinking that all the snow/ice on the roads in the last few weeks has caused considerable damage to our roads.
Once the snow cleared I noticed lots of pot-holes and marble like pieces all over the road.

My question is how does the snow cause this damage?
Is it some kind of chemical reaction or is the snow getting underneath the tarmac somehow and then lifting it?

[Milvus]

It's the action of water freezing and thawing. Water seeps into the surface and when it freezes it expands breaking the surface, more water seeps underneath and when it refreezes more damage is done and so on, showing up as the potholes we are all seeing on the roads

[mxyzptlk]

Water gets into tiny cracks, freezes and expands. which forces the road surface apart,
is my guess

[ll_billym]

This link explains all. With diagrams.

http://news.bbc.co.uk.../magazine/8453969.stm

[Old_Geezer]

It is down to the abnormally mild winters we've had over the last few decades that the damage caused by traditional winter weather looks so severe.

That said, the surfaces are clearly very susceptible to ice damage. I'm a bit surprised we haven't found a way to make them more weatherproofed by now.