Cementitious Composite Materials for Self-Sterilization Surfaces

This paper studies the antibacterial activity of different TiO2 nano -structures (fine-particulate TiO2, TiO2-anatase, and TiO2-rutile) for self-sterilization applications. It is divided into three parts. The first part deals with the investigation of radical production by means of the p-nitrosodimethylaniline (RNO)-bleaching method. In the second part, the effect of incorporating TiO2 into a cement-based composite on its microstructure is evaluated. In the third part, the antibacterial performance is assessed. The results demonstrated that fine-particulate TiO2 has the highest rate of hydroxyl radical production (2.5 times higher than that of TiO2-anatase) owing to its high specific surface area. TiO2 nanoparticles tend to agglom-erate/aggregate during the mixing process, reducing the surface area available for the photocatalytic process. However, fine -particulate TiO2 agglomeration can be suppressed under strong alkaline conditions. A significant antibacterial effect was achieved by the sample with fine-particulate TiO2. The percentage of the infected area is less than 5% for the cement sample containing 5% of fine-particulate TiO2, while the control specimen has more than 15% of the infected area.