Self-cleaning performance of nano-TiO₂ modified metakaolin-based geopolymers

Geopolymer is an alternative binder to Portland cement. In this paper, nano-TiO₂ was incorporated into a metakaolin-based geopolymer matrix to impart photocatalytic properties into the binder. The self-cleaning performance of the resulting binders was revealed under UV and direct sunlight irradiation. The effects of nano-TiO₂ inclusion on compressive strength, microstructure, solar reflectivity, wettability, and decomposition of Rhodamine B (RhB) of the resulting binder were reported. Results showed the compressive strength, total solar reflectance (TSR), and photoinduced hydrophilicity and contaminate decomposition of geopolymer increases with TiO₂ dosage. TiO₂ particles mainly act as fillers to densify the binder. The resulting TiO₂ metakaolin geopolymer has a compressive strength of 61 MPa and a surface TSR of 72%. The addition of TiO₂ imparts photocatalysis properties into the geopolymer, which activates super-hydrophilicity of the surface and assist in the complete decomposition of RhB dye after direct sunlight exposure.