Use of aqueous emulsions based on propylethoxysilane oligomers as an additive in hydraulically setting cement compositions for reduction of shrinkage characteristics

1. An aqueous emulsion, comprising:

a propylethoxysilane oligomer mixture or a mixture of a propylethoxysilane oligomer mixture and octyltriethoxysilane in a weight ratio of 3:1 to 1:3,

at least one emulsifier or an emulsifier system,

at least one content of N,N-diethyl-2-aminoethanol, and

water,

wherein said emulsion has a pH of 8 to 12; and

wherein, when added to a cement mixture, shrinkage of a hardened cement mixture is reduced relative to a hardened cement mixture which does not contain said emulsion

wherein the emulsion has a content of propylethoxysilane oligomer mixture of 20% to 85% by weight, based on the total weight of the emulsion, wherein an oil phase totals 40% to 85% by weight, based on the total weight of the emulsion.

2. The aqueous emulsion according to claim 1 , wherein the propylethoxysilane oligomer mixture contains oligomers of the formula (I)

wherein

the R 1 groups are independently n- and i-propyl,

the R 2 groups are ethyl, and

n determines the oligomerization level at 2 to 20.

3. The aqueous emulsion according to claim 1 , wherein the emulsion contains 0.1% to 1% by weight, based on the total weight of the emulsion, of N,N-diethyl-2-aminoethanol.

4. The aqueous emulsion according to claim 1 , wherein the emulsion comprises at least one further additive selected from the group consisting of preservatives, anticorrosion aids, drip-off aids, rheology aids, sodium hydrogencarbonate.

5. The aqueous emulsion according to claim 1 , wherein the emulsifier or the emulsifier system which is based on at least two of the emulsifiers which follow is selected from the group consisting of alkyl sulphates having C 8 -C 18 -alkyl, alkyl ether sulphates and alkaryl ether sulphates having C 8 -C 18 -alkyl in the hydrophobic radical and having 1 to 40 ethylene oxide (EO) and/or propylene oxide (PO) units, alkylsulphonates having C 8 -C 18 -alkyl, sodium laurylsulphate (C 12 -C 16 ), alkarylsulphonates having C 8 -C 18 -alkyl, and monoesters of sulphosuccinic acid with monohydric alcohols or alkylphenols having 5 to 15 carbon atoms, alkali metal and ammonium salts of carboxylic acids having 8 to 20 carbon atoms in the alkyl, aryl, alkaryl or aralkyl radical, alkyl and alkaryl phosphates having 8 to 20 carbon atoms in the organic radical, alkyl ether or alkaryl ether phosphates having 8 to 20 carbon atoms in the alkyl or alkaryl radical and 1 to 40 EO units, alkyl polyglycol ethers and alkaryl polyglycol ethers having 8 to 40 EO units and C 8 -C 20 carbon atoms in the alkyl or aryl radicals, ethylene oxide/propylene oxide (EO/PO) block copolymer having 8 to 40 EO and/or PO units, addition products of alkylamines having C 8 -C 22 -alkyl radicals with ethylene oxide or propylene oxide, alkyl polyglycosides having linear or branched, saturated or unsaturated C 8 -C 24 -alkyl radicals and oligoglycoside radicals having 1 to 10 hexose or pentose units, silicon-functional surfactants or mixtures of two or more of these emulsifiers.

6. The aqueous emulsion according to claim 1 , wherein the emulsifier or emulsifier system is a mixture of at least one anionic emulsifier and at least one nonionic emulsifier which is present in an amount of 0.02% to 3% by weight, based on the total weight of the emulsion.

7. The aqueous emulsion according to claim 1 , wherein the emulsion is used to an extent of 0.1% to 5% by weight, based on the amount of cement present in the cement mixture.

8. The aqueous emulsion according to claim 1 , wherein the hydraulically setting cement mixture is a mortar, screed or concrete.

9. A hydraulically setting cement mixture, comprising:

the aqueous emulsion according to claim 1 .

10. The hydraulically setting cement mixture according to claim 9 , which is selected from the group consisting of mortar, screed and concrete.

11. The hydraulically setting cement mixture according to claim 9 , which is selected from the group consisting of porous concrete, reinforced concrete, underwater concrete, textile fiber concrete, concrete repair mortar, mortar, 2-component mortars and screed.

12. A method for reducing of a shrinkage characteristic of a hydraulically setting cement mixture, said method comprising:

adding the aqueous emulsion according to claim 1 to a hydraulically setting cement mixture;

wherein said shrinkage characteristic of said hydraulically setting cement mixture is reduced compared to the shrinkage characteristic in a standard mortar according to EN 196 as measured according to DIN EN 52450, 1985-08, using measuring instrument B of the DIN procedure.