Assessment of self-cleaning properties on concrete façade panels

Building façades are affected by atmospheric pollution and other external agents that can impact aesthetic aspects and lead to the appearance of anomalies with impacts on the durability and performance of materials. The reduction in maintenance costs and the preservation of the original characteristics of coatings make the use of photocatalytic semiconductor materials highly attractive, particularly for the conservation of historical heritage. These materials can maintain the cleanliness of building surfaces, promote the degradation of pollutants, and have decontamination and antibacterial effects. Thus, the objective of this study was to develop and evaluate the self-cleaning properties of cementitious panels for façades, aiming to obtain a coating with characteristics to contribute to the preservation of built heritage through the incorporation of titanium dioxide (TiO2) nanoparticles and zinc oxide (ZnO) microparticles. To evaluate the self-cleaning, a Rhodamine B (RhB) solution was deposited on the surfaces of concrete samples, which were subjected to 5 irradiation phases by a lamp simulating sunlight totalling 720 minutes. Visual analysis and colour characterisation tests were carried out to evaluate the self-cleaning capacity. The results showed that the treatment improved surface cleanliness after exposure to light while preserving the original aesthetics of the surfaces.