Synthesis and application of calcium silicate hydrate (C-S-H) nanoparticles for early strength enhancement by eco-friendly low carbon binders

Abstract

Abstract C-S-H–PCE nanocomposites are known to perform as highly effective seeding materials in Portland cement. Here the effectiveness of a C-S-H–PCE nanocomposite admixture on early strength development of eco-friendly cements (clinker blended with up to 35% fly ash or calcined clay) was investigated. First, C-S-H–PCE nano-composites were synthesized from Ca(NO3)2/Na2SiO3 via a co-precipitation method and their particle size distribution was analyzed. Differently structured PCE comb polymers based on IPEG chemistry were used in the synthesis. Nanofoils of ∼50 nm length were identified as most promising seeding material. Furthermore, addition of such C-S-H–PCE nanofoils was found to substantially increase mortar strength at early ages, particularly after 6–24 h of curing. Isothermal heat flow calorimetry and in-situ XRD measurements indicate that silicate hydration in cement is significantly accelerated. Most remarkably, C-S-H–PCE also was confirmed to speed up the pozzolanic reaction of fly ash and calcined clay and to stimulate the formation of hemicarbo aluminate (Hc), especially in calcined clay cement. Thus, C-S-H–PCE can foster the more widespread use of eco-friendly CEM II/III cements.