Improvement of cement-based mortars by application of photocatalytic active Ti–Zn–Al nanocomposites

Photocatalytic active TiO2 has been extensively applied in construction material science due to its ability to remove pollutants from material surfaces. New inorganic–inorganic nanocomposite photocatalyst based on layered double hydroxides (LDHs) associated to TiO2 were introduced in order to increase the compatibility of photocatalyst with cement-based mortars. Different materials were prepared and characterized: cement paste with Ti–Zn–Al powder, mortar with cement paste finishing layer containing Ti–Zn–Al LDH and mortar with Ti–Zn–Al coatings. Degradation of methylene blue under UV light was selected as photocatalytic test reaction. The correlation between surface properties and photocatalytic activity was analyzed. The synergetic effect between TiO2 and Zn–Al-LDH contributes to pronounced photocatalytic performances, improving at the same time mortar performances as an important indicator of the compatibility of photocatalyst with mortar. The photocatalyst introduction procedure influences the active sites surface concentration, giving preference to surface coating method. However, introduction of photocatalyst into the bulk, having lower photocatalytic activity, results in an overall more stable system for prolonged application.