Synergistic enhancement mechanism of nano-TiO 2 on the mechanical properties and photocatalytic performance of geopolymers

Nano-TiO 2 was used as a photocatalytic material in combination with FA-GGBS-based geopolymer materials to study the mechanism by which the photocatalytic and mechanical performance of geopolymers containing nano-TiO 2 is enhanced synergistically. Test results showed that the highest NOx degradation efficiency (58.1%) was achieved in the photocatalytic test at a nano-TiO 2 content of 3%. Mechanical performance tests showed that the performance of the test specimens significantly improved at an admixture content of 3% compared with the control group. Improvement in flexural strength was more pronounced than improvement in compressive strength, increasing by 125.43% after 28 day. The photocatalytic polymer exhibited the most effective pore filling at a nano-TiO 2 content of 3%. Nano-TiO 2 promotes the formation of N-A-S-H gel but inhibits that of C-A-S-H gel. In the later stages of curing, the ratio of N-A-S-H to C-A-S-H gels in photocatalytic geopolymers changes accordingly. Existing studies on the effect of nano-TiO 2 on the mechanical properties of geopolymers reveal that nano-TiO 2 improves the mechanical performance of geopolymers via pore filling effect and serving as nucleation sites to accelerate hydration reactions.