TiO2 photocatalysis in cementitious systems: Insights into self-cleaning and depollution chemistry

The present work offers a general overview about application of titanium dioxide (or titania), TiO2, photocatalysis to concrete technology in relation to enhanced aesthetic durability and depollution properties achieved by implementing TiO2 into cement. Chemistry of degradation of Rhodamine B (RhB), a red dye used to assess self-cleaning performances of concretes containing TiO2, as well as oxidation of nitrogen oxides (NOx), gaseous atmospheric pollutants responsible for acid rains and photochemical smog, is investigated using two commercial titania samples in cement and mortar specimens: 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). Experimental data on photocatalytic performances measured for the two samples are discussed in relation to photocatalyst properties and influence of the chemical environment of cement on titania particles. Impacts on applications in construction concrete are also discussed. (C) 2011 Elsevier Ltd. All rights reserved.