4. New-Generation Cement-Based Nanocomposites with Nano SiO₂-Coated TiO₂

Nano SiO₂-coated TiO₂ combines the excellent mechanical and functional properties of nano TiO₂ with the pozzolanic activity of nano SiO₂. Owing to the modification of the interface of TiO₂ by coating with nano SiO₂, Ti–O–Si bonds can be formed at TiO₂ surface. Such chemical bonds can bring more negative charges at the surface of NT, which are conducive to its dispersion in water due to electrostatic repulsion. Therefore, nano SiO₂-coated TiO₂ is a kind of highly dispersed nanoparticle with core–shell structure. The cement-based nanocomposites incorporated with nano SiO₂-coated TiO₂ demonstrate very strong static and dynamic mechanical properties as well as improved bond properties due to the high dispersibility and the modification effect of nano SiO₂-coated TiO₂ on the structures of cement-based composites. They also show good electromagnetic shielding and absorption properties because of the high dielectric constant of nano SiO₂-coated TiO₂. Especially, the cement-based nanocomposites incorporated with nano SiO₂-coated TiO₂ exhibit notably anti-corrosion properties because of the antibacterial, self-cleaning, and photocatalytic abilities of nano SiO₂-coated TiO₂, indicating their considerable potential application in sewage, marine, health care, and education infrastructures.