Effectiveness of a calcium silicate hydrate – Polycarboxylate ether (C-S-H–PCE) nanocomposite on early strength development of fly ash cement

[Display omitted] •Synthetic C-S-H–PCE nanocomposite prepared by co-precipitation from Na2SiO3/Ca(NO3)2.•C-S-H–PCE enhances early strength (6–24 h) of mortar and concrete of fly ash cement.•No any adverse effect on final strength.•C-S-H–PCE accelerates silicate hydration•C-S-H–PCE also stimulates the pozzolanic reaction of fly ash. C-S-H–PCE nanocomposites are known seeding materials for Portland cement. Here, the effectiveness of a C-S-H–PCE admixture on early strength development of a fly ash blended cement (35 wt% fly ash) was investigated. It was found that addition of C-S-H–PCE drastically increases the compressive strength of mortar and concrete, particularly at 6–24 h of hydration. XRD and calorimetric measurements confirm that the hydration of C3S/C2S in cement is greatly accelerated. Most interestingly, however, the C-S-H–PCE nanocomposite also stimulates the pozzolanic reaction of fly ash, thus explaining the exceptionally high early strength values. Accordingly, C-S-H–PCE might also be useful in other CEM II cements holding pozzolanic materials.