Studies on early stage hydration of tricalcium silicate incorporating silica nanoparticles: Part I

• Dissolution of C3S is accelerated in presence of nanosilica.
• XRD results revealed the presence of additional C–S–H at early stages of hydration in nanosilica incorporated C3S.
• Nanosilica causes supersaturation of calcium hydroxide 30 min later.
• 50% addition C–S–H formed in the presence of nanosilica.
• More polymerized C–S–H is formed using nanosilica.

Hydration of tricalcium silicate (C3S) in presence of nano silica at early stage has been investigated and formation of addition calcium silicate hydrate (C–S–H) has been quantitatively estimated. Prepared C3S was hydrated in the presence of powder nanosilica (30–70 nm) using w/b ratio 0.4 for paste study and 5.0 for aqueous phase study. Results of ICP and XRD showed that the stage of supersaturation of Ca2+ is delayed by 30 min and formation of secondary/additional C–S–H starts at the early stages of C3S hydration in the presence of nano silica. This additional C–S–H is responsible for higher dissolution of C3S as observed by FTIR. SEM/EDX results show the formation of denser C–S–H with low C/S ratio in the presence of nano silica, whereas TG analysis revealed the formation of additional C–S–H (∼50%) in nano silica incorporated C3S system which is accountable for the higher specific surface area as obtained by N2-adsorption.