Concrete is a surprisingly large source of C02 emissions, and it’s the second-most used substance on earth, behind only water.

Our growing maze of concrete freeways and buildings now produces eight percent of global CO2 emissions. That’s even higher than the three percent produced by the aviation industry.

It’s one reason the Minnesota Department of Transportation was out at its MnROAD facility near Albertville this week laying 35 new pavement mixes that incorporate things like fiber and recycled bottles.

They’ll test the mixes beneath the tires of real Interstate 94 drivers. The facilities includes 3.5 miles of highway that run parallel with the westbound lanes. Traffic can be diverted to that stretch, where the test patches are laid.

Glenn Engstrom, director of the facility joined Climate Cast this week to talk about MnDOT’s efforts to reduce the use of concrete.

Click play on the audio player above or subscribe to the Climate Cast podcast to hear the conversation.

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