Effects of the use of TiO₂ on the early ages of white cement-based mortars: analysis of chemical, physical, mechanical, and photocatalytic properties

The study of white cement-based mortar mixtures prepared according to ASTM C-109 with self-cleaning and heterogeneous photocatalytic properties after seven days of curing, prepared by mixing white cement 30 CPC 30 RB, water, and silica, is presented here. To achieve the self-cleaning property, titanium dioxide TiO₂ P25 with a crystal structure of anatase and rutile (80:20) and particle size of 20 nm were added by weight proportion of 0.5, 1, 3.0, and 5.0%. X-ray diffraction and scanning electron microscopy coupled with structural characterization revealed that the material which presents the highest degree of cleanliness was the one containing 5% TiO₂ because the presence of the photocatalyst gives a stronger self-cleaning property to the cement-based material, achieving a 26% degradation of Rhodamine B after 8 h of sun exposure. In addition, it was found that the cement containing TiO₂ presented a compressive strength 8–12% lower than the reference material without TiO₂. The thermal expansion coefficient of the specimens was 7.4 × 10^–6 K⁻¹. It is concluded that itis possible to obtain self-cleaning cement-based materials without affecting their physical–mechanical properties and maintain the expansion coefficient.