Early strength development of cement composites using nano-calcium silicate hydrate (C-S-H) based hardening accelerator

Abstract

A nano- C-S-H is used as a seeding material for the early strength development of cement composites. This work mainly focused on the synthesis process for preparing a C-S-H using the low-cost chemical method for early strength gain in cement composites. The synthesis process involves the utilization of industrial waste (rice husk ash) as a silica source. A synthetic C-S-H was synthesized by extracting silica from rice husk ash and calcium-bearing salt used as a calcium source. A sodium silicate solution is prepared from rice husk ash and then a diluted calcium solution is added over a continuous stirring in order to precipitate C-S-H. Finally, this C-S-H is used as a hardening accelerator in cement composites. The synthesized C-S-H was further characterized using X-ray diffraction (XRD), Scanning electron microscopy (FE-SEM) imaging. The C-S-H in aqueous solution is used at different dosages to investigate the early strength development using isothermal calorimetric and compressive strength tests. The microstructural changes also be investigated using characterization studies. The findings indicate that incorporating C-S-H results in higher compressive strength early ages (at 1 day). Furthermore, the addition of C-S-H resulted an acceleration in cement hydration and suggested an additional hydration product at early stages of cement hydration.