Rhodamine B Discolouration on TiO2in the Cement Environment: A Look at Fundamental Aspects of the Self-cleaning Effect in Concretes

The present work addresses the photocatalytic properties of two commercial titanias for application in concrete technology. A microsized, m-TiO2(average particle size 153.7 nm ± 48.1 nm) and a nanosized, n-TiO2 (average particle size 18.4 nm ± 5.0 nm) have been tested. Cement paste samples (CEMI 52.5 cement, w/c=0.4) containing both photocatalysts have been evaluated based on Rhodamine B (RhB) discolouration under U.V. light, a standard test for self-cleaning cementitious materials. Experimental data are discussed in relation to photocatalyst properties (e.g.: particle size), dye adsorption and degradation characteristics. The influence of the chemical environment on photocatalyst performance and its impact on applications in construction concrete are also discussed.