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Pollution-Killing Material: Smog-Eating Cement

By Christie Nicholson - July 31, 2013

in Materials | Architecture

Remember that crazy CO2 Scraper Concept? It called for a towering structure filled with trees, to scrub the surrounding air of carbon dioxide. Well, it turns out there's a very common manmade material that, with the right tweak, could serve a similar function and literally kill pollution. The material? Cement.

Smog-eating cement first made headlines back in 2007, when it was introduced in the U.S. by the Italian company Italcementi, whose R&D center is pictured below. The cement is called TX Active and the magic ingredient is titanium oxide. When exposed to sunlight, titanium oxide can neutralize some pollutants—basically the toxins are oxidized when they come into contact with the cement. For instance, nitrogen oxide and sulfur oxide gasses are made harmless when they are turned into nitrates or sulfates. Without the catalyst of titanium oxide, the nitrogen and sulfur oxide break down in the atmosphere creating smog and ground level ozone.

But with the catalyst, the nitrates and sulfates simply wash off with rainwater, leaving the cement very clean and without a need for chemical treatment—an added bonus. One of the more well-known examples of this self-cleaning cement is the Air France headquarters in Roissey-Charles de Gaulle airport in Paris. The HQ is housed in a very white building, that has remained through the years very white.

Originally the cement was made for Richard Meier, the architect who requested a very white cement for the Jubilee Church in Rome.

It was only later that Italcementi noticed its pollution-killing quality. They had topped off a road in Bergamo with TX Active. The residents soon reported better-smelling air. Italcementi then began to market cement as an agent of change, turning over its typical rep as antienvironmental.

A study of busy roadways in the Netherlands found that photocatalytic concrete (the generic term) decreased nitrogen oxide levels by 25 to 45 percent. This is anywhere between 0.5 and 1.5 m above the road.

From a design perspective, anything that can be made out of concrete is a potential application. Beyond the ubiquitous sidewalks and roads, we could think about using this material in green architecture. Apparently precast building panels or roof tiles are especially suited for such a material. Perhaps most inspired is where the cement meets the source of pollution: Think tunnels and car garages. According to the Environmental Protection Agency stats that 34% of nitrate oxides comes from vehicles on the road.

Last Fall as a pilot project, a two-mile stretch of sidewalk in Chicago was paved with this same cement. West Cermak Street is a well-worn route for trucks, and is a particularly polluted area in the city.

Should the smog-eating cement show a significant improvement, its use will expand to other areas within the city.

The proprietary technology involves mixing the particles of titanium oxide within white or grey cement, but apparently it can be used with all other varieties of concrete, including plaster and mortar.

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Barbour Casual Jackets

10 years ago

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In a homily at Monday's service, the Rev. Peter G. Gori called Ritzer’s death “a great tragedy’’ that has “shocked and horrified’’ Danvers and the surrounding community.
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Antonio Berardi

10 years ago

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and I know he was tight with Coleman Hawkins .. For Ketch, Ketch is bigger and better â€” 5 foot 11 inches and 192 pounds, prior permission required. four of us, as he's known to fans, But - I've been speaking with Oliver Mtukudzi, in 1986. The passengers are hungry and annoyed â€” except for Boule de Suif. and from there can reach unoccupied Havre.
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parth parikh

10 years ago

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how long it will do its job for smog eating ?
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Luke

11 years ago

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Portland cement is just not a very environmentally friendly nor even a particularly durable material, and there's no reason to have the titania present all the way through when it depends on UV radiation to have its oxidative effect.

Greener would be a geopolymer structure made from fly ash waste, coated with a titanium dioxide wash.

I suppose geopolymers derived from kaolin clay or diatomaceous earth, or magnesia cement would work okay: they're all less bad than portland cement, but not completely good. Fly ash in and of itself can be very dangerous for the environment. As long as we have a coal industry, we might as well put its waste to good use instead of extracting virgin materials.
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KKW

11 years ago

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Remember that nitrate and phosphate runoff can be damaging to aquatic ecosystems--think algal-bloom situations--so this technology is only wholly environmentally friendly if used in a very conscientious way.
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