Hydration, mechanical performance and porosity of Portland cement pastes with functionalized nanosilica with APTES

Abstract

This study reports on the microstructure of Portland cement pastes with nanosilica (NS) and amino-functionalized nanosilica (NSF). For this, NSF dispersion was prepared in a two-phase reaction system, consisting of an aqueous dispersion with dichloromethane, using 3-aminopropyltriethoxysilane (APTES):NS molar ratio 1:28.62. Cement pastes were analyzed in the fresh state by consistency and in the hardness state by compressive strength, conduction calorimetry, X-ray diffraction (XRD), thermal analysis (TGA), infrared spectroscopy (FTIR) and mercury intrusion porosimetry (MIP). It was verified that the functionalized nanoparticles affected the hydration kinetic properties, indicating the extension of the induction period. Through microstructural analysis, it was observed that NSF increased the amount of the main mineralogical phases generated during Portland cement hydration or the pozzolanic reaction. Therefore, the NSF improves the Portland cement hydration and contributes to the densification of the microstructure of the cement pastes at 28 days.