Construction Research & Technology Gmbh

Evonik Degussa Gmbh

Kerstin Becher

Harald Grassl

Alexander Kraus

Philipp Wieland

Gerhard Albrecht

Jochen Mezger

Ulrich Fischer

Eva Jetzlsperger

Stefanie Scheul

Christian Hübsch

Christian Huebsch

Dispersion which is free of binders and which contains silica and at least one superplasticizer, the silica being a precipitated silica having a surface area greater than 50 m/g, the aggregates and/or agglomerates in the dispersion having a median diameter of less than 1 &#x3bc;m and the proportion of silica being from 5 to 50% by weight, based on the total amount of the dispersion, and a process for the preparation thereof and the use thereof as a concrete admixture in cement-containing preparations.

Aqueous dispersions of silica for increasing early strength in cementitious preparations

The invention relates to a process for the preparation of a copolymer by free radical mass polymerization of a maleic acid monoester derivative with vinyl ester in the presence of an acid having a pKa of less than 1.8. The copolymer is suitable as a dispersant for hydraulic binders.

Vinyl ester maleic acid derivative copolymers

Pulverulent polycondensation products are described, consisting of The pulverulent polycondensation products according to the invention are outstandingly suitable in construction material mixtures in an amount of from 0.1 to 5% by weight, based on the weight of the construction material. The pulverulent polycondensation products have a number of advantages here, such as, for example, excellent storage stability, good liquefying action at low dosage and industrially simple production.

Pulverulent polycondensation products

Disclosed is a polycondensation product that is a reaction product of A) an aromatic or heteroaromatic compound containing 5 to 10 C atoms or heteroatoms and is provided with an average of 1 to 300 oxyethylene groups and/or oxypropylene groups per molecule which are linked to the aromatic or heteroaromatic compound via an O atom or N atoms, and B) an aromatic compound and C) an aldehyde selected among the group of formaldehyde, glyoxylic acid, and benzaldehyde or mixtures thereof. Surprisingly, the inventive polycondensation product causes very good liquefaction of hydraulic binding agents, eg. Cement, resulting in substantially improved liquefaction of the construction material at a lower dose while pourability can be maintained over a longer period of time as opposed to naphthalene sulfonates or melamine sulfonates.

Polycondensation product based on aromatic or heteroaromatic compounds, method for the production thereof, and use thereof

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Waldhausen, Germany

Kerstin Becher