TiO2- containing cement pastes and mortars : measurements of the photocatalytic efficeintcy using a rhodamine B - based colourimetric test

The photocatalytic activities of cement pastes and mortars, containing various amounts of titanium dioxide (TiO2) in the anatase form, were evaluated and compared. The density, total porosity and pore size distribution of the materials were measured, and the amount of TiO2 being at their surfaces was estimated. The photocatalytic efficiency was evaluated by monitoring the discolouration of rhodamine B applied to the surface of the materials which were then exposed to artificial sun light; this evaluation was based on the use of a dimensionless specific activity coefficient. For TiO2 contents higher than 1 wt% (up to 5 wt%), cement pastes exhibited a photocatalytic activity higher than that of mortars because their activity was roughly proportional to the TiO2 content, whereas the activity of mortars levelled off. On the other hand, the type of cement used to prepare the materials had a low effect on the photocatalytic performances.