Impact of nano-TiO2 on white Portland cement mortars: a combined XRD coupled rietveld, crystallographic and microstructural analysis

Abstract

Abstract The present study investigated the structural, microstructural, and crystallographic changes associated with the addition of nano-TiO2 (NT) by intermixing and surface coating on freshly cast and hardened coatings on white Portland cement matrix samples at minimal dosages. Scanning electron microscopy (SEM) and VESTA were employed to analyze the microstructure morphology of the hydration products and the crystal structure parameters of the NT-modified white Portland cement mortar. Additionally, Rietveld refinement analysis was performed to quantify the crystal phases coupled with XRD using Xpert High Score Plus and Expo-2014 software. The Rietveld refinement analysis of the hardened coating surface followed by the fresh cast coating resulted in the most refined structural model compared with that of the intermixed and reference samples. The integration of NT also reduced the bond distances and polyhedral volumes, indicating denser atomic packing and enhanced interactions between the smaller NT particles and the white Portland cement matrix and enhancing the structural integrity within the matrix. Furthermore, SEM micrographs revealed a compact microstructure with enhanced CSH and reduced CH crystals in the NT-modified white cement mortar samples. The presence of hydration products and corresponding bonds were confirmed by Fourier Transform Infrared Spectroscopy.

Keywords

• Nano TiO2 (NT)
• White Portland cement
• Microstructure
• Crystallography