EFFECT OF WELL-DISPERSED NANO-TiO₂ ON SULPHOALUMINATE CEMENT HYDRATION AND ITS APPLICATION IN PHOTO-DEGRADATION

Nano-TiO ₂ and sulphoaluminate cement have been received sustained attention due to their environment-friendly characteristic, respectively. Particular attention was paid to their materials composite. To better understand the effect of nano-TiO ₂ on sulphoaluminate cement hydration and its application in photo-degradation, the composite systems of cement paste (mortar) with well-dispersed nano-TiO ₂ were investigated by mechanical analysis, Rietveld/XRD, SEM, porosity analysis and photocatalytic test. The results reveal that nano-TiO ₂ can be well dispersed under ultrasonic treatment of 15min when the sodium hexametaphosphat is chosen as the dispersant. And the well-dispersed nano-TiO ₂, with the dosage of 0.2wt%, has the most significant effect on the mechanical improvement. Micro-analysis show that the mechanical promotion by nano-TiO ₂ is not attributed to the hydration degree increase but microstructure optimization. It is reflected in the decrease of porosity, mainly affecting the transitional pores (D=10~100nm), and spatial structures modification of cement paste where AFt was more likely to form as needle shape with shorter length-diameter ratio. The photocatalytic test demonstrates that the composite system (cement paste) has long-term effective photo-degradation property