Old Faithful spews thousands of gallons of water high into the air, but elsewhere at Yellowstone National Park, another wonder is quietly gulping water down.
The park recently unveiled a new 4,000-square-foot walkway built with Flexi-Pave, an asphalt replacement made of recycled tires and stone. Just one square foot of the material can absorb 3,000 gallons of water per hour.
Kevin Bagnall, founder and CEO of KBI, the company that created Flexi-Pave in 2001, says the technology is especially useful for Yellowstone because the park’s geothermal system supports two-thirds of the world’s geysers.
Unlike asphalt or concrete, which wicks water away from the surface, Flexi-Pave’s porous material allows rainwater to shoot straight into the earth, where it can settle in nearby aquifers.
Flexi-Pave is 23% porous, thanks to a careful combination of tires, stone, and a proprietary binder invented by KBI. That allows it to absorb rainwater quickly, which keeps storm runoff from mixing with local contaminants before entering the water supply. That helps decrease water pollution, which is especially important at Yellowstone.
“We were the material of choice because of the zero environmental impact that we have,” Bagnall tells Business Insider.
In total, the park used 1,536 shredded Michelin tires to create a 4,160-square-foot path.
Bagnall has a larger vision for Flexi-Pave outside Yellowstone. As urbanisation and population density both increase, he says conserving clean water will become a much larger concern.
Flexi-Pave is already being used in 200 to 300 cities across the US, Bagnall says. But in time he hopes KBI can expand to every major city around the world so that Flexi-Pave can become the default material used in all urban construction projects: roads, footpaths, parking lots.
Flexi-Pave isn’t the only “thirsty” concrete on the market. There’s also Topmix Permeable, a similar product made by British building materials company Tarmac. The material uses fine pieces of granite instead of recycled rubber and can absorb 880 gallons of water per minute, according to the company.
But Bagnall believes rubber is the superior choice to granite because it won’t crack or settle — a quality he calls flexibility.
“Our most valuable resource is water,” Bagnall says. “If [Flexi-Pave] can be used in better urban planning, that valuable water is going to go back into the earth where it would naturally go, and therefore we’d be keeping the levels of our aquifer for potable water supplies.”
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