Type of nano-TiO2 incorporation in to self-cleaning cement mortars has influence on crystal microstructure properties

The present study evaluated the self-cleaning performance of cement mortar samples under prolonged exposure to particulate matter incorporating nano TiO 2 (NT), and assessed through total solids and total dissolved solids. NT particles were incorporated into white Portland cement (WPC) mortars at a minimal dosage to investigate their microstructure and crystallographic properties on intermixed and surface-coated mortar samples. SEM-EDAX and XRD studies were performed to examine the morphology, hydration products and elemental composition of the NT-incorporated WPC mortar discs. Rietveld refinement coupled with XRD was employed for crystal phases quantification, and crystallographic analysis was conducted to examine the crystal parameters such as bonds, atoms, polyhedral structures and lattice characteristics of WPC modified with and without NT. This finding suggested that the improved interconnectivity in the atomic arrangements and bonding within the crystal lattice resulted in a denser cement matrix. The microstructure of the NT-incorporated samples also showed denser microstructures with fewer voids and increased CSH gel compared to those of the control. The bond distances and angles between cations (Ca 2 + , Ti 4+ , Si 4+ ) and oxygen anions (O 2- ) revealed that surface-coated samples coated with NT exhibited enhanced Ca–O bond interactions, while intermixed samples exhibited strong Ca–Ti interactions. However, the strong Ca–Ti bond angle intermixing and greater Ca–O–Si angle in surface-coated samples suggest that NT influences calcium–silicate–hydrate formation, and the O–Ti–O bond angles in intermixed and hardened coatings suggest strong NT–cement matrix interactions.