Upon extensive research in the area of photocatalysis, construction materials and construction products could be equipped with novel functionalities. Photoactive construction materials such as paving stones, saddle stones or roofing tiles reduce the concentration of harmful NO2 (nitrogen dioxide) fast and efficiently.
The effects of photoactive construction materials are due to special titanium dioxide (TiO2) photocatalysts, which can be embedded into the construction materials via different approaches. Regarding paving stones or concrete slabs, either the whole concrete paving stone / slab is equipped with the photocatalyst or only the shell concrete facing consists of TiO2-enriched concrete, which might influence the mode of action.
Figure: Various photoactive construction materials
Regarding roofing tiles only a very thin surface-layer is enriched with the special TiO2, thereby generating the photoactive effects.
The photocatalyst TiO2 is permanently bound in the construction material, but not chemically altered. TiO2 is not consumed during the reaction and transformation of the material does not occur. Thus, the photoactive properties of constructions materials such as concrete stones or roofing tiles last the whole life of the product.
Due to this innovative technology the following advantages can be stated:
- Photoactive paving stones reduce the concentration of nitrogen oxides an hydrocarbons in the air and thereby to contribute to a less polluted environment. The pollutants from exhaust emissions are reduced in the head space of the photocatalytic paving by surface reactions. The reduction of pollutants could be accelerated up to 30fold through the creation of photoactive paving areas.
- The surfaces of the construction materials do not only reduce harmful nitrogen oxides, furthermore certain inorganic and organic pollutants, such as sulfur oxides, volatile organic compounds and ozone, are reduced.
- In addition to the reduction of pollutants, photoactive construction materials exhibit an improved soiling resistance. The risk of a microbial infestation with algae, fungi or mildew is significantly reduced. This can be a positive side-effect of photoactive products with respect to the conservation of value.