Comparative study on cementitious products containing titanium dioxide as photo-catalyst

Motivated by the promising results of the research on photo-catalytic materials and their application in building materials, various products have been introduced onto the European market so far. First applications have been carried out as coating on glazing and tiles. In recent years, this has been extended to cementitious products such as paving blocks. A comprehensive scientific description is often limited to the advertised product – to the authors’ knowledge comparative analyses of different products have not been presented yet. This paper presents the first results of a comparative study carried out with concrete products suitable for air purification. Tests are performed using a set-up based on the draft version of the ISO standard TC 206/SC N for the degradation of nitric oxides under laboratory conditions. Based on the laboratory observations, recommendations in regard to the practical execution of tests as well as their analysis are given. This practical experience motivated the development of an alternative test setup for the assessment of UV-A-induced degradation processes considering the variation of boundary conditions like UV-A irradiance, humidity, volume flow, and pollutant concentration. A brief technical description of this test setup will be presented to the reader.