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Public Radio's Environmental News Magazine (follow us on Google News)

The Road to Better Air

Air Date: Week of

A greener form of blacktop is in the works. Sandra Larson reports.


GELLERMAN: It’s Living on Earth, I’m Bruce Gellerman. Just ahead: for peat’s sake, residents of a Scottish island say no to a wind farm. But first this Cool Fix for a Hot Planet from Sandra Larson.


LARSON: Vehicles on the road are often blamed for unhealthy air and global warming. But what about the road itself?

It turns out asphalt – or at least the production of it – also emits unhealthy fumes and greenhouse gases.


LARSON: Researchers at the National Center for Asphalt Testing, along with the Federal Highway Administration, are studying a new and more environmentally-friendly asphalt.

About 60 million tons of “hot mix asphalt” pave US roads every year. It’s made by mixing a sand and rock aggregate with a hydrocarbon liquid, and heating the brew to around 300 degrees. This energy-intensive process spews greenhouse gases and hazardous fumes.

European countries have developed a way to make asphalt at temperatures fifty to one hundred degrees lower. This “warm mix” process cuts carbon dioxide emissions by 30 to 40 percent and nitrous oxides by up to 70 percent. Dust and fumes are reduced, too - and it takes less fuel to make.

The U.S. researchers are studying how the pavement will hold up here under harsh temperatures and heavy use, and how to adapt the new process to larger manufacturing plants.

Last year, an experimental road was paved in Yellowstone Park using warm mix asphalt. And it’s in the plans for other projects, from highways in Texas to runways in Massachusetts. So it looks like warm asphalt is a hot prospect.

In the traffic jam of the future, you may be comforted to know that at least the road you’re stuck on is fuel-efficient.

That’s this week’s cool fix for a hot planet. I’m Sandra Larson.



The National Asphalt Pavement Association

Warm Mix Asphalt Technologies and Research at The Federal Highway Administration

The National Center for Asphalt Testing at Auburn University

Boston Logan Airport to use WMA on runway project


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