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Today, in a world context characterized by high pollution levels and increasingly limited natural resources, even in the building sector, focusing on environmental issues, through energy saving and a more rational use of these resources, both during construction and management, is fundamental. An important contribution in this direction is given by the knowledge of the durability of products and building components, especially when innovative products are applied and no information are available on the reliability and service life. The research concerns the evaluation of the durability of cement-based photocatalytic coatings ("rasanti" in the Italian diction), containing different types of pigments, used for the external finishing of the buildings envelope and applied in low thicknesses on different supports. These products were prepared using photocatalytic cements by Italcementi (TX ActiveR) The investigated aspects are: the photocatalytic properties, conferring self-cleaning attitude and reduced maintenance to the treated surfaces, and the colorimetric ones, meaning the conservation of colour and giving aesthetic quality to the building envelope. The paper presents some results carried out on TX ActiveRcement-based coatings, performed according to the ISO 15686 methodology, aimed at defining the Reference Service Life, through accelerated ageing tests in climatic chamber and the corresponding monitoring of photocatalytic and colorimetric properties. The photocatalytic tests were carried out according to the UNI 11247-2010, in terms of NOx abatement capability, and the colour measurements were taken on the CIELAB colour space.

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.