DE3840579A1 - Process for producing gas concrete - Google Patents

Abstract

Process for producing gas concrete (aerated concrete) by mixing a slurry comprising binders, aggregates and water with a hydrogen-developing expanding agent (foaming agent, gas-developing agent) and optionally further additives, with aqueous solutions or aqueous dispersions of organopolysiloxanes containing Si-bonded hydrogen being used as expanding agent.

Description

The invention relates to a method for producing Gas concrete using Si-bonded hydrogen having organopolysiloxane as a blowing agent, which developed hydrogen under basic conditions.

Gas concrete components are light and have a high heat insulation. They are easy to edit and are considered fire-resistant according to DIN 4102.

The production of gas concrete is known per se (R. Wende Horst, "Building Materials Science", Vincentz-Verlag Hannover 21st ed., 1975, pages 225-8; Karl Krenkler, "Chemistry in Building", Vol.1: Inorganic Chemistry, Springer-Verlag Berlin Heidelberg New York, 1980, pages 310-3). Here are übli aggregates, binders and water into one Porridge mixed and with a gas-generating agent (propellant tel), such as Aluminum powder, calcium carbide or water fabric peroxide, mixed. That for the production of gas concrete aluminum powder mainly used so far developed under given basic conditions within about 30 Minutes of hydrogen, which leads to the formation of pores in the gas concrete mass leads, the volume of the mass depending on the The amount of blowing agent used increased considerably. The long drive time is caused by the fact that as a drive medium a solid is used, which is in the slurry Additives, binders and water is insoluble and  therefore only slowly by the basic solution due to a chemical reaction must be solved. This long driving time has the consequence that the gas concrete is not on assembly line systems can be manufactured. In addition, the long drift prevents time the use of gas concrete as an inorganic foam insulation fabric with voids, e.g. Cable ducts, can be foamed.

As an alternative to aluminum powder, DDR-PS 7 53 387 (chemical factory of Heyden; issued March 2, 1953) describes the use of "dioxodisiloxane" as a blowing agent with the sum formula H ₂ Si ₂ O ₃ . From this patent together with contemporary literature, such as G. Becherer, O. Düring, Naturwissenschaften 43 (1956) 13, 300 and E. Wiberg, W.Simmler, Z.anorg.allg.Chem. 283 (1956) 26, 401- 13, it is apparent that the not common name "Dioxodisiloxan" a high polymer, crystalline compound having the empirical formula is _x meant (HSiO _3/2). The correct systematic name for this compound would be poly (silsesquioxane).

The process according to GDR PS 7 53 387 has two major disadvantages. On the one hand, there is the blowing agent used "Dioxodisiloxane" is a powder that is in water and mei most other solvents is completely insoluble (cf. E.Wiberg, W.Simmler, Z.anorg.allg.Chem. 283 (1956) 26, 401- 13). This will slow the problem outlined above Gas development with aluminum powder with "dioxodisiloxane" unsolved.

Secondly, the blowing agent "dioxodisiloxane" is not easily accessible in larger quantities (see e.g. E.Wiberg, W.Simmler, Z.anorg.allg.Chem. 283 (1956) 26: 401-13; US 27 31 485; US 28 44 435), so that an application in industrial Scale is eliminated.  

The task was to create a blowing agent of gas concrete, which is the propellant very much quickly developed and at the same time, if desired, as Water repellents can act. This task is accomplished by solved the invention.

The invention relates to a method for manufacturing of aerated concrete by mixing a paste of binders, Develop aggregates and water with a hydrogen the blowing agent and, if necessary, other additives, since characterized in that as blowing agent aqueous solutions or aqueous dispersions of Si-bonded hydrogen having organopolysiloxanes are used.

The aqueous solutions of Si bound hydrogen-containing organopolysiloxanes preferably contain organopolysiloxanes from units of formula

wherein R is identical or different, monovalent, free of basic nitrogen, SiC-bonded organic radicals, R ¹ monovalent, SiC-bonded radical with basic nitrogen, which may also be the same or different, R ² identical or different alkyl radicals with 1 to 4 Carbon atom (s) per radical means x 0, 1, 2 or 3, on average 0 to 2, on average preferably 0 to 1.8, y 0 or 1, on average 0.1 to 0.6, on average preferably 0.15 to 0.3, z 0 or 1, on average 0.2 to 1, on average preferably 0.5 to 1, p 0.1.2 or 3, on average 0 to 0.8, on average preferably 0.01 to 0, 6 and the sum of the respective average values of x, y, z and p is at most 3.4.

Examples of free of basic nitrogen, SiC-bound organic radicals R are in particular hydrocarbon radicals with 1 to 20 carbon atoms per radical, such as alkyl radicals, e.g. the methyl, ethyl, n-propyl and isopropyl radical and Octadecyl residues; aliphatic hydrocarbon residues with at least one double bond, e.g. the vinyl and alkyl residue and butadienyl residues; cycloaliphatic hydrocarbons leftovers e.g. the cyclohexyl radical and methylcyclohexyl radical te; aromatic hydrocarbon residues, e.g. the phenyl radical and naphthyl residues; Alkaryl residues, e.g. Tolyl residues and aral alkyl residues, e.g. the benzyl radical. These hydrocarbon residues may have substituents that are Si-bonded Hydrogen, basic nitrogen and hydroxyl groups Temperatures below 50 ° C are inert. Examples of such Substituted hydrocarbon residues are fluorinated carbons hydrogen residues, such as the 3,3,3-trifluoropropyl residue; out Carbon, hydrogen, ether oxygen and fluora tom (s) constructed monovalent aliphatic radicals, such as the 1,1,2,2,3,3-hexafluoropropyloxypropyl and the 1,1,2,2- Tetrafluoroethoxypropylrest, and ether oxygen as the only one monovalent coal water containing ge (n) substituents radicals such as p-methoxyphenyl.

Especially because of the easy accessibility are considered as of basic nitrogen-free, SiC-bound organic residues in the organopolysiloxanes used according to the invention Methyl residues preferred. It is further preferred that at each Silicon atom to which a hydrogen atom is directly bonded is also a hydrocarbon residue, especially a Me thylrest, is bound.  

SiC-bonded radicals with basic nitrogen and thus as radicals R ¹ are those of the formula

R³₂ NR⁴-

preferred, in which R ^{3 is} hydrogen or identical or different alkyl or amino or iminoalkyl radicals and R ^{4 is} a divalent hydrocarbon radical.

The examples of alkyl radicals R also apply in full to the alkyl radicals R ³ . However, preferred is at each nitrogen atom in the residues of the formula

R³₂ NR⁴-

bound at least one hydrogen atom.

The divalent hydrocarbon radicals R ⁴ preferably contain at most 20 hydrocarbon atoms per radical. Examples of such hydrocarbon radicals are the methylene and ethylene radical, and also propylene, butylene, cyclohexylene, octadecylene, phenylene and butenylene radicals. The n-propylene radical is preferred in particular because of the easy accessibility. The radical of the formula is particularly preferred as the SiC-bonded radical with basic nitrogen and thus as the radical R ¹

H₂N (CH₂) ₂NH (CH₂) ₃-

Further examples of SiC-bonded radicals with basic nitrogen and thus for radicals R ¹ are those of the formula

H₂N (CH₂) ₃-
H₂N (CH₂) ₂-
H₃CNH (CH₂) ₃-
H₂N (CH₂) ₅- and
n-C₄H₉NH (CH₂) ₂NH (CH₂) ₃-

Examples of radicals R ² are in particular the methyl, ethyl and isoproyl radical.

The compounds used according to the invention with Si-bun denen hydrogen and at least one SiC-bound radical with basic nitrogen can for example by equilibrium burn or condense e.g. gamma-aminoethylaminopro pyltrimethoxysilane or gamma-aminoethylaminopropylmethyldi methoxysilane or mixtures of such silanes with Organopolysiloxanes that are free of basic nitrogen, however, contain Si-bonded hydrogen will. The organopolysiloxanes used here are available methyl endblocked by trimethylsiloxy groups hydrogenpolysiloxanes or copolymers of trimethyl siloxy groups, dimethylsiloxane and Methylhydrogensiloxane units.

Examples of such organopolysiloxanes are those of the formula

(CH₃) ₃Si- (O-Si (CH₃) ₂) _x - (O-SiHCH₃) _y -OSi (CH₃) ₃

with the proviso that x is 0 to 100 and y is 50 to 200, with x being 0 and y being 40 to 60 being particularly preferred.

The organopolysiloxane used in the invention or a Mixture of at least two such organopolysiloxanes in water, optionally with the addition of acid, such as vinegar acid, dissolved.

The aqueous dispersions used as blowing agents Organopolysiloxanes containing Si-bonded hydrogen preferably contain organopolysiloxanes from units of formula

wherein a is 0, 1, 2 or 3, on average 1.0 to 2.0 and b is 0, 1 or 2, on average 0.0 to 0.5 and where R ^{5 may be the} same or different, is a hydrogen atom or a monovalent one Hydrocarbon radical having 1 to 8 carbon atoms per radical, which may have substituents which are inert to water, and R ^{6 may be the} same or different, a hydrogen atom or an alkyl or alkoxyalkylene radical each having 1 to 4 carbon atoms Rest means.

In the manufacture of the aq containing dispersions of Si-bonded hydrogen Organopolysiloxanes are in accordance with the German application the file number P 37 17 075.9 (M. Wolfgruber, Wacker-Chemie GmbH, registered on May 21, 1987) or the corresponding Registration in the United States with US Ser. 1 95 567, US 34 33 780 (J. Cekada, Jr. and D.R. Weyenberg, Dow Corning Corporation, issued March 18, 1969) and U.S. 4,424,297 (A.E. Bey, Dow Corning Corporation, issued January 3 1984) preferably silanes or mixtures of silanes formula  

R⁵ _a Si (OR⁷) _{4- a}

used, where a and R⁵ each have the meaning given above and where R⁷ may be the same or different, an alkyl or alkyloxyalkylene radical having 1 to 4 carbon atoms per radical or a radical of the formula

-COCH₃, -COC₂H₅ or -CH₂CH₂OH

means.

Mixtures of silanes of the formula HSi (OR ⁷ ) ₃ and R ⁵ _a Si (OR ⁷ ) _{4- a} , which are preferably in a molar ratio of 100: 0 to 10:90, particularly preferably 100: 0 to 30:70, are used are set, wherein a, R ⁵ and R ⁷ each have the meaning given above, with the proviso that the silane R ⁵ _a Si (OR ⁷ ) _{4- a} at least one SiC-bonded hydrocarbon radical having 1 to 8 carbon atoms (en ) per residue that may have substituents that are inert to water.

These mixtures can be used to prepare aqueous dispersions which, when used as blowing agents, additionally impart water-repellent properties to the gas concrete produced according to the invention.
Examples of radicals R ⁵ are the methyl, ethyl, propyl and octyl radical.
Examples of R ⁷ radicals are the methyl, ethyl, propyl and butyl radical.
Preferred radicals R ⁵ are the propyl and octyl radical.
Preferred R ⁷ radicals are the methyl and ethyl radicals.

In the manufacture of the aq gene dispersions of Si-bonded hydrogen containing  Organopolysiloxanes can also partially hydrolyzate the first mentioned silanes or silane mixtures with no more than 10 Si atoms can be used per partial hydrolyzate.

To produce the aqueous used according to the invention Dispersions of Si-bonded hydrogen Organopolysiloxanes can optionally from alkoxy groups free organo (poly) siloxanes with a maximum of 8 siloxane units per molecule in a mixture with at least one alkoxysilane and / or its partial hydrolyzate can be used. As Or gano (poly) siloxanes with a maximum of 8 siloxane units each For example, linear organo (poly) siloxanes can be used as molecules of the formula

R⁵₃SiO (SiR⁵₂O) _nSiR⁵₃

are used, where n 0 is an integer from 1 to 6 and where R ^{5 has} the meaning given above for it. Preferably n is 0, and hexamethyldisiloxane is particularly preferred. Cyclic organo (poly) siloxanes of the formula, for example, can also be used as organo (poly) siloxanes with a maximum of 8 siloxane units per molecule

(R⁵₂SiO) _m

can be used, where m is an integer from 3 to 8, preferably 4, and wherein R ^{5 has} the meaning given above for it.

The aqueous dispersions used according to the invention are by adding at least one alkoxysilane and / or its partial hydrolyzate and optionally in a mixture with organo (poly) siloxane free of alkoxy groups with a maximum of At least 8 siloxane units per molecule in the presence of water of emulsifier with a maximum rate of 5 moles  Organosilicon compound per hour and liter of water, esp special from 0.5 to 1.0 mole of organosilicon compound each Hour and liter of water and subsequent distillation of the hydrolytically formed alkanol. The Her position takes place in an acidic, neutral or basic environment, preferably at 15 to 90 ° C and preferably at pressure the surrounding atmosphere, i.e. at about 1020 hPa (absolute), or, if desired, even higher or lower To press.

The preparation of the aqueous used according to the invention Dispersions can be discontinuous, semi-continuous or be carried out continuously. Preferably the production by a method according to the German Registration with file number P 37 17 075.9 (M. Wolfgruber, Wacker-Chemie GmbH, registered on May 21, 1987) or the corresponding registration in the USA with US Ser. 1 95 567, in which ge continuously from each other separates the above organosilicon compounds and that Water, with at least one of the two substances emulsifier contains, is fed to a reactor.

The Dis Emulsifiers used include carboxylic acids 9 to 20 carbon atoms, aliphatic-substituted benzenesulfonic acid ren with at least 6 carbon atoms in the aliphatic Substi tuenten, aliphatic-substituted naphthalenesulfonic acids with at least 4 carbon atoms in the aliphatic substituents ten, aliphatic sulfonic acids with at least 6 carbon atoms in the aliphatic substituents, with silylalkylsulfonic acids at least 6 carbon atoms in the alkyl substituents, alipha table-substituted diphenyl ether sulfonic acids with at least 6 carbon atoms in the aliphatic substituents, alkylhydro gene sulfates with at least 6 carbon atoms in the alkyl substitutes quaternary ammonium halides and quaternary  Ammonium hydroxides. All acids mentioned can be used as such or optionally used in a mixture with their salts will.

The preferred emulsifier is dodecylbenzenesulfonic acid.

The emulsifier is preferably used in amounts of 0.5 to 2.9 % By weight, particularly preferably 1.0 to 2.0% by weight, based on the weight of those contained in the aqueous dispersion Organosilicon compound used.

The aqueous dispersions of Organopolysiloxanes containing Si-bonded hydrogen preferably have an average particle diameter of 10 to 150 nm and preferably have a Solids content of up to 20 wt .-%, based on the Ge total weight of the dispersion.

The aqueous solutions used according to the invention or aqueous dispersions of Si-bonded hydrogen Organopolysiloxanes can send in any way the porridge from binders, additives and water ver to be mixed.

Mixtures of binders, coarse-grained aggregates and water are generally referred to as concretes (cf. R. Wendehorst, "Baustoffkunde", Vincentz-Verlag Hannover 21st ed., 1975, page 254) and can be produced in a manner known to the person skilled in the art. The binders are, in particular, lime (CaO or Ca (OH) ₂ ) and Portland cement. Examples of additives are sand, vermiculite (expanded mica), perlite (expanded mava), gravel, wood flour and asbestos.

Immediately after adding the blowing agent, the gas concrete Blend hydrogen evolution, which is essentially is completed after a few minutes.

The amount of Si-bonded hydrogen required by the organopolysiloxane, which rapidly develops hydrogen under the given basic conditions, depends - as in the prior art, on the addition of the gas-developing propellants, such as aluminum powder - according to the desired bulk density of the hardened gas concrete and Composition of the gas concrete mix.

The required amount of organo used according to the invention polysiloxane can be based on the chemical reaction that the Development of hydrogen under the given basic conditions based on the chemical structure of the organopolysiloxane used can be calculated. Preferred two They are 0.01 to 0.15 gram atom, particularly preferably 0.03 up to 0.06 gram atom, Si-bound hydrogen per kilogram of the paste from binders, aggregates and water used.

After adding the blowing agent according to the invention Gas concrete mixture in the vessel or for the shaping poured into a cavity to be foamed.

In addition to binder, aggregate, water and blowing agent medium can the porridge before, during or after pouring further additives can be added. examples for this are Setting retarders such as gluconic acid, pigments, e.g. Oxidfar ben and water repellents based on organopoly siloxanes according to DE-OS 30 04 130 (Sumitano Metal Mining Co.- Ltd .; Kanto Denka Kagyo G., Ltd; August 7, 1980), DE-OS 30 44 948 (Wacker-Chemie GmbH, July 1, 1982) and DE-OS 30 04 346 (Internationella Siporex AB, August 28, 1980).  

The amount and the time of addition depend on the nature of the respective additive and is the expert knows.

The process according to the invention is preferably at 10 to 30 ° C and the pressure of the surrounding atmosphere, i.e. about 1020 hPa (absolute), carried out, or if desired, too at higher or lower pressures.

After sufficient green stability has been achieved (see Karl Krenkler, "Chemistry in Building", Vol.1: Inorganic Chemistry, Springer Verlag Berlin Heidelberg New York, 1980, page 80) can the gas concrete molded body depending on the additives used and the desired end product are removed from the shaping vessel and in an autoclave with steam after the Processes known to those skilled in the art that have also been used for setting and curing any building blocks or components under Steam generation were applied to be hardened.

The steam curing in the autoclave can also be omitted especially when using fast curing cements and limes is an advantage.

The process according to the invention for the production of gas concrete using a blowing agent which is very quick Developed hydrogen is suitable for the production of Gas concrete of any kind. In particular, it enables continuous production of gas concrete on a flow tied where common blowing agents due to their long blowing time or other technical difficulties are not used can be. In addition, due to the rapid Hydrogen development of fast-curing cements and limes be used. This makes the use of gas concrete Foaming voids, e.g. a cable duct,  allows, gas concrete in this cavity as inorganic shear, completely non-flammable insulation material.

For the manufactured by the inventive method Gas concrete are all applications of the previous method ren manufactured gas concrete possible.

The following examples are intended to illustrate the invention Procedures are explained in more detail.

In the following, the unit of measurement "parts" always refers to unless another reference is expressly mentioned, to parts by weight.

The aqueous dis used in the following examples persions of Si-bonded hydrogen containing Or Ganopolysiloxanes were made as follows:

In a 5 l three-necked flask with stirrer, dropping funnel, Thermometer and distillation attachment are 3 l of water and 6 g of dodecylbenzenesulfonic acid as an emulsifier and placed on Heated to 65 ° C.

With stirring at 65 ° C and about 300 hPa (abs.) half 4 h 930 g of an organosilicon compound from Table 1 dosed through a capillary immersed in the template. The methanol formed during the hydrolysis is removed distilled, the pressure being regulated so that the Volume of the flask contents constant during the silane addition remains.

After the addition of silane is at 65 ° C and about 300 hPa (Absolutely) constantly stirred for 0.5 h. There are water receive ge dispersions that have a solids content of 10  % By weight, based on the total weight of the dispersion Zen.

Table 1

example 1

1065.0 g crystal quartz powder (type no. 6, Amberger Kaolinwerke) are mixed well with 750.0 g of deionized water. 67.5 g of Portland cement (PZ 350, Heidelberger Zement AG). Then be 270.0 g of fine white lime (type gas concrete, SKW, Trost berg) incorporated.  

36.0 g of the above are described for this gas concrete slurry given dispersion A. In the aerated concrete slurry sets immediately hydrogen evolution. The mud is now in poured an oiled mold container. The Gasent winding is essentially within 2 minutes closed.

After sufficient green stability is achieved Shaped molded body and in an autoclave with the help of Superheated steam (10,000 hPa pressure / 180 ° C) hardened.

After curing, the shaped body has a density of 650 kg / m ³ . The water absorption of the gas concrete after storage for 2 hours on a polyurethane sponge saturated with deionized water is 13 kg / m ² .

Example 2

The procedure described in Example 1 is repeated with the modification that the blowing agent is 67.0 g of the above described dispersion B can be added.

As in Example 1, the driving time of the Ansat is also here zes about 2 minutes.

After hardening, a gas concrete with a density of 640 kg / m ^{3 is obtained} . The water absorption of the gas concrete is 6.5 kg / m ² after storage for 2 hours on a polyurethane sponge saturated with deionized water.

Example 3

The procedure described in Example 1 is repeated with the modification that the blowing agent is 67.0 g of the above described dispersion C can be added.  

As in Examples 1 and 2, the blowing is also here time of preparation about 2 minutes.

After hardening, a gas concrete with a density of 650 e kg / m ^{3 is obtained} . The water absorption of the gas concrete after storage for 2 hours on a polyurethane sponge saturated with deionized water is 5.5 kg / m ² .

Example 4

A mixture of 400 g of a methyl hydrogenpolysiloxane endblocked by trimethylsiloxy groups with a viscosity of about 20 mm ² / s at 25 ° C. and 165 g of gamma-aminoethyl aminopropyltrimethoxysilane is heated to 140 ° C. under nitrogen for 6 hours. The organopolysiloxane obtained in the absence of air is a water-clear liquid with a viscosity of about 7.5 mm ² / s at 25 ° C. It has an amine number (= number of ml of 1-n-HCl required to neutralize 1 g of substance) of 2.63, an amine nitrogen content of 3.7% and contains 1.1% Si-bonded hydrogen.

2 parts of this siloxane and 1 part of acetic acid are ge mixes and dissolved in 3 parts of deionized water.

106.5 g crystal quartz powder (type no. 6, Amberger Kaolinwerke) are mixed well with 125.0 g of deionized water. 6.5 g of Portland cement (PZ 350, Heidelberger Zement AG) and 1.7 g of alumina melt ment stirred. Then 27.0 g of white fine lime (type gas concrete, SKW, Trostberg) incorporated.

To this gas concrete slurry, 4.0 g of that in this Example described aqueous solution of organopolysiloxane  given. Hydrogen Ent immediately sets in the sludge wrapping up. The slurry is now oiled in a Poured molding container. The gas evolution is essential completed within 2 minutes. After reaching The molded body becomes sufficiently green switched off and left at room temperature.

After curing, the molded body has a density of 600 kg / m ³ . The water absorption of the gas concrete after storage for 2 hours on a polyurethane sponge saturated with deionized water is 15 kg / m ² .

Example 5:

The procedure described in Example 4 is repeated with the modification that aminopropyltrimethoxysilane is used instead of the gamma-aminoethylamino propyltrimethoxysilane. The organopo lysiloxane obtained in the absence of air is a water-clear liquid with a viscosity of about 8 mm ² / s at 25 ° C. It has an amine number of 1.3, an amine nitrogen content of 1.1% and contains 1.1% Si-bonded hydrogen.

2 parts of this siloxane and 1 part of acetic acid are ge mixes and dissolved in 3 parts of deionized water.

To produce gas concrete, as in Example 4 wrote procedure. As in Example 4, this is also The batch takes about 2 minutes to drive.

After curing, the molded body has a density of 600 kg / m ³ . The water absorption of the gas concrete after storage for 2 hours on a polyurethane sponge saturated with deionized water is 15 kg / m ² .

Claims (13)

1. A process for the preparation of gas concrete by mixing a slurry of binders, additives and water with a hydrogen-developing blowing agent and, if appropriate, further additives, characterized in that aqueous blowing agents or aqueous dispersions of organopolysiloxanes containing Si-bonded hydrogen are used. 2. The method according to claim 1, characterized in that mixing before shaping, setting and / or the hardening takes place. 3. The method according to claim 1 or 2, characterized net that as aqueous solutions of Si-bound water organopolysiloxanes containing aqueous solutions of such organopolysiloxanes, at least in part in the same molecule both Si-bound What hydrogen as well as at least one SiC-bound residue have with basic nitrogen, are used. 4. The method according to claim 3, characterized in that as aqueous solutions of Si-bonded hydrogen containing organopolysiloxanes, which have at least partially in one and the same molecule both Si-bonded hydrogen and at least one SiC-bonded radical with basic nitrogen, such be used by dissolving organopolysiloxanes from units of the formula wherein R is the same or different, monovalent, free of basic nitrogen, SiC-bonded organic radicals, R ¹ monovalent, SiC-bonded radicals with basic nitrogen, which may also be the same or different, R ² identical or different alkyl radicals having 1 to 4 carbon atoms (en) per residue means x 0, 1, 2 or 3, on average 0 to 2, y 0 or 1, on average 0.1 to 0.6, z 0 or 1, on average 0.2 to 1, p 0 , 1, 2 or 3, on average 0 to 0.8, and the sum of the respective average values of x, y, z and p is at most 3, 4, in water, optionally with the addition of acid, preferably acetic acid . 5. The method according to claim 1 or 2, characterized in net that as aqueous dispersions of Si-bound Organopolysiloxanes containing hydrogen are those which by adding at least one alkoxysilane and / or its partial hydrolyzate and optionally in a mixture with organo (poly) siloxane free of alkoxy groups with maximum at least 8 siloxane units per molecule to water in counter were from emulsifier at a rate of at most 5 moles of organosilicon compound per hour and Liters of water were produced. 6. The method according to claim 5, characterized in that as aqueous dispersions of Si-bonded hydrogen containing organopolysiloxanes those of Or ganopolysiloxanes from units of the formula wherein a is 0, 1, 2 or 3, on average 1.0 to 2.0, and b is 0, 1 or 2, on average 0.0 to 0.5, and where R ^{5 may be the} same or different, a hydrogen atom or a monovalent hydrocarbon radical having 1 to 8 carbon atoms per radical, which may have substituents which are inert to water and R ^{6 may be} identical or different, a hydrogen atom or an alkyl or alkoxyalkylene radical having 1 to 4 carbon atoms each rest means to be used. 7. The method according to claim 5, characterized in that for the preparation of the aqueous dispersions, a mixture of silanes of the formula HSi (OR ⁷ ) ₃ and R ⁵ _a Si (OR ⁷ ) _{4- a} , wherein a 0, 1, 2 or 3rd , on average 1.0 to 2.0, and in which R ^{5 can be} identical or different, denotes a hydrogen atom or a monovalent hydrocarbon radical with 1 to 8 carbon atoms per radical, which may have substituents which are inert to water, and R ^{7 may be the} same or different, an alkyl or alkyloxyalkylene radical having 1 to 4 carbon atoms per radical or a radical of the formula -COCH ₃ , -COC ₂ H ₅ or -CH ₂ CH ₂ OH, is used. 8. The method according to claim 7, characterized in that the silane R ⁵ _a Si (OR ⁷ ) _{4- a} , wherein a is 0, 1, 2 or 3, by average 1.0 to 2.0, and wherein R ⁵ may be the same or different, is a hydrogen atom or a monovalent hydrocarbon radical having 1 to 8 carbon atoms per radical which may have substituents which are inert to water and R ^{7 may be the} same or different, an alkyl or alkyloxyalkylene radical having 1 up to 4 carbon atoms per radical or a radical of the formula -COCH _3, -COC ₂ H ₅ or -CH ₂ CH ₂ OH means at least one SiC-bonded hydrocarbon radical with 1 to 8 carbon atoms per radical against water may have inert substituents. 9. Water repellent gas concrete available by the process according to claim 8. 10. The method according to any one of claims 1 to 8, characterized characterized in that per kilogram of porridge Binding agents, additives and water 0.01 to 0.15 Gram atom of Si-bonded hydrogen is added. 11. The method according to any one of claims 1 to 8 or claim 10, characterized in that the pulp from bindemite additives, water and propellant additives, selected from the group of water repellents, Pigments and setting retarders can be added. 12. The method according to any one of claims 1 to 8 or 10 to 11, characterized in that the gas concrete according to shape steam-hardened in the autoclave. 13. The method according to any one of claims 1 to 8 or 10 to 12, characterized in that the gas concrete is continuous Lich can be produced.