Microstructural and photocatalytic characterization of cement-paste sol-gel synthesized titanium dioxide

摘要

A route for the in paste synthesis of TiO_2 loaded cement is described. TiO_2 sols are blended with fresh cement paste as an alternative process to add photocatalytic functionality to cement. The modification of cement paste structure after the addition of TiO_2 sols is analyzed by XRD, SEM and TGA. As a particular microstructural feature, TiO_2 containing calcium silicate hydrate (C-H-S) particles are identified as networking centers of a C-S-H gel fiber matrix. The increase of the TiO_2 sol concentration induces a decrease of pore size and an increase in the specific surface area in the cement composites. The photocatalytic activity of the TiO_2/cement system is evaluated from the degradation of Methylene Blue (MB) under UV irradiation, monitored through the absorbance at 665 nm. The results show that, although TiO_2 phases reveal no long range order structure, the cement paste exothermal treatment in presence of hydrate products and alkaline conditions leads to a photocatalytic composite. Such new cement matrix may be twofold advantageous since it additionally promotes the formation of C-S-H gel, main determinant of cement mechanical properties.