An environmental friendly solution for air purification and self-cleaning effect: the application of TIO2 as photocatalyst in concrete

Heterogeneous photocatalysis is a rapidly developing field in environmental engineering. It has a great potential to cope with the increasing pollution by traffic. The addition of a photocatalyst to ordinary building materials such as concrete, creates environmental friendly materials by which air pollution or pollution of the surface itself can be diminished. TiO2 is added to a cement mortar in order to diminish the air polluting effect by exhaust gasses. In particular, the conversion of NOx to NO3 is measured. A detailed study of the principles of photocatalysis and of the interaction between TiO2 and concrete is carried out. The laboratory study pointed at the influence of different parameters, such as temperature, relative humidity, light intensity, applied surface, material characteristics and flow rate. An upscaling of the test set-up has been carried out to see the influence of an increase in photocatalytic active surface. In a more global approach, the application of TiO2 as air purifying material is studied to be implemented in the urban and interurban streets and roads. In the European project NR2C, photocatalytic materials and different application methods are studied. This paper presents an overview of the principle of photocatalysis and the application in combination with cement, as well as the results of the laboratory research, especially towards air purifying action. The implementation of this type of material in an urban and interurban area is discussed. A large scale realization with concrete pavement blocks is accomplished on the main roads (Leien) in the centre of Antwerp. An overview of this realization is given.