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US 11,365,151 B2Granted
Accelerating admixture for hydraulic compositions
AssigneeMapei S.P.A.
InventorsGiorgio Ferrari, Alberto Brocchi, Marco Squinzi
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Abstract
The object of the present invention is a novel admixture comprising a hardening accelerator for hydraulic compositions based on Portland cement and other supplementary cementitious materials.
Claims14
Accelerating admixture for hydraulic compositions based on calcium-silicate-hydrate gel (C-S-H) seeds, obtained with the process comprising
- hydrating in aqueous suspension a hydraulic binder based on Portland cement or other hydraulic binders with a mainly silicate base, with a water/binder ratio (W/B) ranging from W/B =1 to W/B=6, at a temperature ranging from 10° C. to 90° C., for times ranging from 2 hours to 300 hours, in the presence of carboxylic acids, the calcium salts thereof, monoethanolamine, isopropanolamine, polyethanolamines, or mixtures thereof,
- wherein dispersing, viscosity-controlling and stabilising agents are added during hydration or at the end of the hydration reaction, and wherein the dispersing agents comprise gluconic acid and the salts thereof, polyethercarboxylate-based polymers, lignin sulphonate, condensates of naphthalene sulphonate and melamine sulphonate with formaldehyde, and derivatives of polysaccharides and phosphonated polymers.
A process for the preparation of an accelerating admixture for hydraulic compositions based on C-S-H seeds, which comprises
- hydrating a hydraulic binder based on Portland cement or other hydraulic binders with a mainly silicate base, in the presence of carboxylic acids or the calcium salts thereof, polyethanolamines or mixtures thereof in aqueous suspension to obtain a suspension,
- wherein the hydrating step reaction of the binder in the aqueous solution is conducted in stirred tanks or reactors at atmospheric pressure, at temperatures ranging from 20° C. to 80° C. and wherein stirring is continuous or discontinuous, with anchor or rotor stirrers, optionally associated with ultradispersion systems.
Dependencies are inferred from the claim text.