In this paper, studies of the mechanical properties and photocatalytic activity of new photoactive cement mortars are presented. The new building materials were obtained by the addition of 1, 3, and 5 wt % (based on the cement content) of nitrogen-modified titanium dioxide (TiO2/N) to the cement matrix. Photocatalytic active cement mortars were characterized by measuring the flexural and the compressive strength, the hydration heat, the zeta potential of the fresh state, and the initial and final setting time. Their photocatalytic activity was tested during NOx decomposition. The studies showed that TiO2/N gives the photoactivity of cement mortars during air purification with an additional positive effect on the mechanical properties of the hardened mortars. The addition of TiO2/N into the cement shortened the initial and final setting time, which was distinctly observed using 5 wt % of the photocatalyst in the cement matrix.

The studies of some mechanical properties and photocatalytic activity of new cements with photocatalytic activity are presented. The new building materials were obtained by addition of semi-product from titanium white production. Semi-product was calcined at 300 and 600 °C for one, three, and five hours and then this material was added to cement matrix in an amount of 1 and 3 wt.%. New materials were characterized by measuring the flexural and compressive strength and the initial and the final setting time. The photocatalytic activity was tested during NOx photooxidation. The cement with photocatalytic activity was also characterized by sulphur content measurements. The measurement of reflectance percentage of TiO2-loaded cements in comparison with pristine cement and TiO2 photocatalyst calcined at 600 °C were also performed. It should be emphasized that although in some cases, the addition of photocatalyst reduced the flexural and the compressive strength of the modified cements, these values were still within the norm PN-EN 197-1:2012. It was also found that the initial and the final setting time is connected with the crystal size of anatase, and the presence of larger crystals significantly delays of the setting time. This was probably caused by a water adsorption on the surface of anatase crystals.

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