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

Abstract

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.

Keywords

cement composites / photocatalytic TiO₂ / sol-gel / C-S-H gel / microstructure

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