Offenbach: Novel asphalt is supposed to cool down cities

• fromFabian Scheuermann

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The road construction company Lutz Weiler has developed a road surface that absorbs water and lets it evaporate again. A test track will be built in Offenbach this year.

An employee of “Asphaltbau und Mischwerke GmbH” in Offenbach uses a fire hose to spray water onto the asphalt. It almost disappears – as if you were pouring it into a hole and not on a road surface. Lutz Weiler stands next to it and is pleased that the demonstration makes an impression. The architect and road construction company developed the new type of covering that swallows the water. In fact, the asphalt, for which Weiler has applied for a patent under the name “Klimaphalt”, is said to be a true all-rounder and to arm the cities for several consequences of climate change.

But from the beginning. First there was a conversation a year and a half ago between Weiler, who runs several road construction companies in Offenbach, and his two daughters. Politicized through “Fridays for Future”, they told their father about the expected violent consequences of climate change in this country too. “I had to find out that I have no idea,” admits Weiler. But the topic didn’t let him go. He immersed himself in the subject, read specialist literature every evening. And developed his new asphalt – it is not the first surface that the Bad Vilbeler created.

“We are building a field,” the 59-year-old tries to explain his invention with the water after the demonstration. So the new asphalt should work more like nature and less like the city. First, by properly storing rainwater in a layer filled with volcanic rock. This relieves the burden on the canals, which are often insufficiently dimensioned for the heavy rain to be expected as a result of climate change. Furthermore, the asphalt releases part of this water back into the environment via evaporation. This ensures that the cities, which continue to heat up, cool down somewhat around the new streets.

In addition, the covering is lighter than usual, which means that it reflects more sunlight and remains cooler. On a test piece on his company premises on Sprendlinger Landstrasse, you could see this clearly in winter, as Weiler shows in the photos. Nowhere did the snow stay long – only on a piece of lawn and on the area with the new asphalt.

Of course, that also has its price. “Klimaphalt” is more expensive than the dark standard goods. Nevertheless, Offenbach’s city service ESO is planning this summer to install a 150 square meter test area on the Upper Grenzstrasse, which is also used by buses, to test whether the material does what it says on the tin. An engineering office accompanies the experiment. The head of road construction and maintenance at ESO, Thomas Möller, says that reliable data will probably only be available in a few years: Then you know how the asphalt reacts to permanent stress and weather changes and whether it retains its grip, for example.

Weiler moved from Frankfurt-Harheim to Offenbach five years ago with his companies and around 85 employees – including aerospace technicians. He hadn’t found a suitable site in Frankfurt. In Offenbach, on the other hand, he ran open doors for business development: “I was helped within three days,” he recalls. He found what he was looking for on the factory premises of the Fredenhagen company, which produced, among other things, conveyor systems for the automotive industry on Sprendlinger Landstrasse until 2009.

Gradually, the entrepreneur is now converting the site according to his ideas: He has just had a hall roof painted white – so that solar radiation and therefore heat is also reflected there. Next is a facade greening. “We’ll have to pull the brake soon,” says Weiler. Otherwise our environment would hardly be worth living in the future.

More infoat www.klimaphalt.de.

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