Formation of C–S–H nuclei using silica nanoparticles during early age hydration of cementitious system

This study is focused on the formation of calcium silicate hydrate (C–S–H) seeds during the pre-induction and induction period of hydration in the presence of silica nanoparticles (SNPs). In addition to this, the effect of the formed C–S–H seeds on the hydration kinetics of tricalcium silicate (C3S) is also well investigated and elucidated. From the X-ray diffractometer results, it is observed that the optimum dosage of SNPs for the formation of C–S–H seeds within 60 min of hydration is 3% and the incorporation of SNPs in C3S phase also results in the delayed formation of crystalline calcium hydroxide nuclei. From the isothermal calorimetry and thermogravimetric analyzer results, it is observed that the presence of SNPs results in the shortening of the induction period of C3S hydration. From the Fourier-transform infrared spectroscopy and field emission scanning electron microscope results, it is observed that the presence of SNPs results in the accelerated early hydration rate of C3S and polymerization in the silicate chain. These results reveal that significant acceleration in C3S hydration occurred after the formation of C–S–H seeds.