Hardened oil well cement paste modified with TiO2@SiO2 nanoparticles: Physical and chemical properties

Core/shell TiO2@SiO2 nanoparticles (nTS) were added to cement class G, and their physical and chemical properties were investigated with and without polycarboxylate (PC). The hardened cement pastes were analyzed through gas pycnometry, Brunauer-Emmett-Teller (BET), field emission scanning electron microscopy (FE-SEM), and compressive strength. For hydration characterization, portlandite quantification, and C-S-H analysis, Xray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and 29Si magic-angle spinning nuclear magnetic resonance (29Si MAS NMR) were performed. The nTS demonstrated a self-dispersive behavior and increased the specific mass and matrix compacity. Moreover, the total pore volume decreased, and the compressive strength increased. The nTS improved the hydration degree, reduced portlandite content, and increased C-S-H main chain length.