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

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 (similar to 50%) in nano silica incorporated C3S system which is accountable for the higher specific surface area as obtained by N-2-adsorption. (C) 2014 Elsevier Ltd. All rights reserved.