TiO2-treated different fired brick surfaces for biofouling prevention: Experimental and modelling results

Biofouling on building façades, caused by the growth of bacteria, algae, cyanobacteria, fungi, lichens and plants leads to aesthetical degradation and to an increase in the maintenance costs consequently. Recently, the use of nanotechnology to prevent this phenomenon has been increased due to their efficiency and affordable cost. Currently, the research focuses on the numerical modelling of biofouling in order to simulate the biofouling processes and to find the correlations between physical properties of substrata and growth of microorganisms. In this paper, biofouling tests were conducted on fired brick substrata with different intrinsic characteristics (porosity and roughness) by means of an accelerated growth test. Biofouling was evaluated through time by digital image analysis of specimens׳ surface and then the Avrami׳s law was applied to modelize the biofouling process. The model was adapted to include the inhibitory effect of TiO2 and a modified equation of Avrami was proposed. Results show a good agreement between simulation and the experimental data. Furthermore, the assumptions taken into account to discretize the real phenomenon were acceptable. The experimental analysis and the numerical modelling showed how the roughness and the porosity influenced the algal attachment.