Study of the self-cleaning performance of cement-based composites under different illumination conditions: Impact of nano-TiO₂ hydrogel modified with KH-570

Fungus and bacteria are ubiquitous, and the construction industry is inevitably affected by microbial corrosion, especially on the surface of hydraulic structures and components in contact with water. At the same time, in the context of the outbreak of COVID-19, it is particularly critical to develop a new type of green building material that is safe for both the environment and human health. In this study, the effects of different nano-TiO₂ contents on the mechanical properties, working properties, and antibacterial properties of cement-based composites were experimentally investigated. The effects of the nano-TiO₂ content on the microstructure were determined via Fourier-transform infrared spectroscopy, computed tomography, X-ray diffraction, and scanning electron microscopy. The results show that a small amount of nano-TiO₂ gel can effectively make the structure more compact and change the number of hydration products, which can improve the working performance and mechanical properties of the cement-based composites. At the same time, cement-based composites mixed with nano-TiO₂ show antibacterial properties under different light conditions. The overall antibacterial properties improve with the increase in the nano-TiO₂ content. For given light conditions, nano-TiO₂ shows the best antibacterial properties under mercury lamp light. The antibacterial properties of cement-based composites doped with 2 % nano-TiO₂ are optimal under 60 min of mercury lamp illumination.