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

A route for the in paste synthesis of TiO2 loaded cement is described. TiO2 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 TiO2 sols is analyzed by XRD, SEM and TGA. As a particular microstructural feature, TiO2 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 TiO2 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 TiO2/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 TiO2 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.