New cement helps reduce pollution

Castle Cement's TioCem can be used in concrete to decompose air pollutants using a photocatalytic reaction and is based on patented technology.

The emission of exhaust gases from vehicles, heating installations and power stations has increased in recent years, leading to a rise in air pollution.

This has become a growing concern for our health because there is a proven link between poor air quality - particularly evident in congested, densely populated urban areas - and an increased risk of respiratory infections and impaired lung function.

In an attempt to improve air quality, targets have been set to reduce the amount of oxides of nitrogen and this has become a real challenge for local authorities, architects and engineers alike.

That's why TioCem is such an exciting development.

It is cement containing a special nano-crystalline grade of titanium dioxide, which can be used in concrete to decompose oxides of nitrogen and other substances by photocatalysis.

It has also been widely reported to provide "self-cleaning" properties by the same photocatalytic process.

Daylight initiates a reaction where the active concrete surface converts harmful nitrogen oxides (NOx) into harmless nitrates (NO3-) This in turn reacts with the calcium hydroxide of the concrete surface and drains off with the next rainfall.

Furthermore, the reaction doesn't consume the photocatalyst, so it keeps on working.

Other grades of titanium dioxide are used for many aspects of common daily use such as cosmetics and pigments for paints.

Cement-based materials containing TioCem have excellent potential in urban pollution control.

The technique is particularly effective when applied to wide horizontal or vertical surfaces, for example in the construction of pavements for busy streets, roads, parking areas and hard standings.

That makes TioCem suitable for a range of building materials, including paving slabs, roof tiles, facade elements, block paving, tunnel linings and noise barriers.

The results of an environmental monitoring campaign in a central street in Bergamo, Italy, in November 2006 showed a successful reduction of NOx using photocatalytic concrete block paving.

When comparing an untreated section of asphalt road with an adjacent renovated area using photocatalytic concrete block paving, it showed abatement of pollutants within the block paving section up to 56%.

TioCem corresponds to EN 197-1, the recognised European standard for common cements and its processing and durability properties are equivalent to standard cement.

"TX Active" is a quality mark used to validate the photocatalytic activity of building materials where strict standards have been defined for the cement as well as for the products produced using TioCem.

Only manufacturers of products using TioCem will be allowed to show the TX Active logo.

TioCem represents a real opportunity for authorities, architects, engineers and concrete producers to address the problem of air pollution control.

It is available within the UK from Castle Cement under a licence partnership between HeidelbergCement AG and Italcementi SpA.

For further information contact Brian Roach at French Jones on 014091 410987.

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