The science beneath pothole problems - NBC12 - Richmond, VA News

The science beneath pothole problems

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By Andrew Freiden - bio | email

RICHMOND, VA (WWBT) - They're more than a little bump in the road, potholes are a big nuisance this time of year. And you can blame water for these driving hazards.

A lot of you think snow plows are responsible for creating potholes -- although they may occasionally damage pavement, the real culprit is water.

When melted snow and ice seeps into tiny cracks in pavement, it starts the process of creating a pothole.

They key is water's peculiar molecular qualities. When water is cooled to near freezing, it starts expanding.

In fact, when water turns to ice, it gains about 10 percent in volume. Here's proof: we put a container in the freezer to see what happens.

After a few hours, it's frozen solid -- and the lid is bulging outward. That expansion process packs a lot of power and can rip apart roadways.

It works like this: liquid water sneaks into tiny cracks in roads, then freezes. Instead of expanding a plastic container, it's the crack in the pavement that expands. Then as vehicles drive over, those cracks turn into gaping potholes.

Our pothole problem is made worse because we typically see daytime temperatures above freezing. So during cold snaps like the one we've been having can bring a freeze/thaw cycle, and more pavement damage, until eventually a fix is needed.

Next time you see a pothole -- steer clear, and blame good old H2O.

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