A Comparative Study on Structural, Crystallographic and Microstructural Properties of Nano-TiO2 Intermixed and Surface-Coated Portland Cement Mortars

The present study aimed to investigate the influence of minimal nano TiO2 (NT) on the microstructural and crystallographic analysis of various application methods, such as intermixing, fresh cast coating, and hardened coating, for ordinary Portland cement (OPC 53 grade) mortar. X-ray diffraction coupled with Rietveld refinement was employed to quantify the crystal phases. The structural parameters, such as unit cell dimensions, lattice parameters, volumes, and crystallographic integrity of the OPC mortar discs with and without NT were examined. Additionally, scanning electron microscopy was employed to analyze the microstructural morphology and hydration products with NT integration. The results showed that the hardened NT coating led to the most refined structural model with the shortest bond distances and smallest polyhedral volumes in the crystal structure. This suggests that the denser packing of atoms with stronger atomic interactions between the smaller NT particles within the cement matrix created a more compact and uniform microstructure. This microstructure improvement, which is evident by less calcium hydroxide formation and denser calcium-silicate hydrate formation, improved the overall performance of the OPC cement mortar with minimal NT dosages.