Why Isn't Smog-Gobbling Concrete More Popular?

Right now, Milan is gearing up for a huge environmental and sustainability exposition, the Expo Milano 2015, which opens next May. You can’t miss the Italian Pavilion, which will play host to the event. Armed with an urban forest aesthetic, the white geometrical structure looks a bit like a freezer-burned ice cube. But what makes it truly special is what it's made of: biodynamic cement.

Recently nominated for a European Inventor Award, this “smog-eating concrete” is one of those inventions that feels truly futuristic. The cement is mixed with photocatalytic substances that use sunlight to break down pollutants, washing them away with rainwater.

But the main question is: If Italy is doing it, why hasn’t the rest of the world caught on?

“I’ve been working on it for 20 years,” said Italian chemist Luigi Cassar, the inventor of smog-eating concrete. “Not everyone will invest in the research.”

While with the Italcementi Group, Cassar first invented smog-eating concrete back in the 1990s. The first building was completed in 2000 by architect Richard Meier, while the smog-eating product hit the market in 2006 as TxActive. Today, anywhere between 20 and 50 buildings have been built with smog-eating concrete. (Cassar said there is no official count). But why not more?

“If 15 percent of buildings in cities were coated with TxActive, you could cut 50 percent of the pollution,” he said.

"That’s a lot, especially for car pollutants” said Cassar. “We hope the results will push all the companies to invest more in this material, especially cement manufacturers.”

While it sounds like an ideal solution for Beijing, there have been no meetings with China. While it would be useful for New York, the first American city to line its streets with smog-eating sidewalks is Chicago.

Granted, it’s more expensive than regular concrete, but still cheaper than an alternative option: protective water-repellent, silicone coatings for buildings, which are aimed at protecting exteriors from getting mucked up by pollution. While that was the initial goal of the smog-gobbling concrete, the environmental aspect is a great side benefit.

“Our main motivation was to keep the color of buildings the same and this was accomplished—we have buildings that have remained stable in both in white and grey,” Cassar said.

In the meantime, the focus remains on the Expo designed by Nemesi & Partners, which used over 2,000 tonnes of concrete just for the façade. The team is using biodynamic cement panels with a technology from Styl-Comp, which was developed at Italcemeni's research and innovation lab for architectural sustainability called i.lab. They say the mortar is 80 percent recycled, including scraps from Carrata marble for a bright white look. They named it the “Tree Nursery Italy.”

While Milan is far from having its air quality improved with one (or a few) buildings, the hope is that the technology will continue to take off.

“We have it in part of a town but not a substantial quantity of the town,” said Cassar. “That’s the biggest challenge.”