Canadian Consulting Engineer

New cement eats pollution

December 13, 2007
By Canadian Consulting Engineer

One of the sessions at Construct Canada in Toronto at the beginning of December featured a cement additive with fut...

One of the sessions at Construct Canada in Toronto at the beginning of December featured a cement additive with futuristic qualities. Not only does the technology enable concrete to clean itself, but it also enables the concrete structure to clean up pollutants in surrounding air.
Jim Whiting of Essroc/Italcementi explained that their TX Active technology uses photocatylitic cements that work through molecular adsorption and an oxidative reaction. Basically the sun’s ultraviolet rays react with the treated cement, then rainwater can wash pollutants off the concrete surface. The catalyst is part of the cement and so is present in the concrete for ever. It can remove most organic and some inorganic pollutants within a few hours, although certain graffiti will take a long time to go. It will not remove mineral oxide pigments and rust.
Essroc has two products: TX Arca cement provides the self-cleaning, and TX Aria cement gives an added ability to eat up pollution in the surrounding environment up to a few metres around the surface.
Whiting showed some demonstration tests done in Milan, Italy, one of the most polluted cities in Europe. The product was applied in a thin coating of less than a centimeter on the surface of concrete walls, and air conditions up to three metres around the walls were measured. The tests showed that air levels of nitrogen oxides were reduced by 50-60%, he said, and VOCs “somewhat.”
The technology has been used on a number of buildings in France, Italy and in the U.S. The prize case is the Misericordia church in the Vatican City, otherwise known as the Jubilee church. It opened in 2003 and was designed by architect Richard Meier. The slides showed a gleaming white building with a series of vertical curving “shells” treated with TX Arca that were as pristine as the day they were poured. Other buildings where TX Arca been used include Air France’s headquarters in Paris, a school, a prison, and a tunnel where the coating was used with artificial UV light sources. On a building where the walls were in permanent shade tests showed the technology still worked.
Asked what the formula of the product is, Whiting said it uses titanium dioxides, but would not elaborate.
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