Functionalized transition metal doped silicate hydrate/PCE nanocomposites: an innovative hardening accelerator

Some inorganic and organic chemicals have been known for a long time for their ability to accelerate the hydration reaction of Portland cement. These species include chlorides, thiocyanates, nitrates, formates, alkanolamines and other chemicals and the mechanism through which the acceleration occurs vary according to the specific admixture. More recently, metal silicate hydrate MeSH/PCE nanocomposites aqueous suspensions were developed as hardening accelerator; they constitute the most powerful accelerator available today and they do not suffer from any shortcoming. In our previous works, we have demonstrated that copper is well suited for the preparation of MeSH/PCE nanocomposites. We then demonstrated that, in such nanocomposites, copper ions occupy surface silicate sites. Copper is known for its tendency to easily form complexes with a variety of chemical species, in particular N-donor ligands, such as alkanolamines. In this work we investigate the existence of interactions between different alkanolamines and the copper ions on the surface of a copper doped MeSH/PCE nanocomposite. The new surface functionalized MeSH/PCE nanocomposite is tested as hardening accelerator in mortars prepared with Portland cement where it is shown to be far superior compared to the amine-free copper-MeSH/PCE. In addition, we show how the accelerating performance of the surface functionalized MeSH/PCE nanocomposite is much higher than the sum of the effects of the copper-CSH/PCE nanocomposite and the alkanolamine, suggesting a synergetic effect of the functionalized product.