THE DURABILITY OF INNOVATIVE CEMENTITIOUS COATINGS: PHOTOCATALYTIC ACTIVITY AND COLOUR

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 (TXActive®). 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. Some results are reported, 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 lab activity was based on 6 cycles of accelerated ageing induced to the samples by the alternation of varying conditions of temperature (2 to 70°C), humidity (0 to 100%), rain and UV radiation. The photocatalytic activity measurements were carried out according to the UNI 11247-2010, in terms of NOx abatement capability, as shown in Fig. 1. The colorimetric measurements were taken on the CIELAB colour space and Fig. 2 shows the results of the monitoring of colour, by spectrophotometer, in terms of Colour Difference (DE*ab) variation. The comparison between the graphs shows an interesting relationship between the two monitored parameters.