EP1945589A1

EP1945589A1 - Use and method for reduction of corrosion

Info

Publication number: EP1945589A1
Application number: EP06819238A
Authority: EP
Inventors: Urs Mäder; Franz Wombacher; Beat Marazzani
Original assignee: Sika Technology AG
Current assignee: Sika Technology AG
Priority date: 2005-11-04
Filing date: 2006-11-03
Publication date: 2008-07-23
Also published as: WO2007051833A1; RU2008122344A; BRPI0618187A2; KR20080072036A; US20090218545A1; CN101331093A; US8012543B2; CA2628484A1; AU2006310541A1; JP2009515038A

Abstract

The invention relates to a use of a composition containing polyorganosiloxane S and a method of reducing corrosion on steel reinforcement in reinforced concrete constructions, and also a concrete structure which is produced using such compositions. It is highly suitable for the renovation of old concrete but also for inhibition of corrosion of reinforcing iron in fresh concrete.

Description

USE AND METHOD FOR CORROSION REDUCTION

Technical area

The invention relates to the field of corrosion inhibition of steel reinforcements in concrete structures. More particularly, the invention relates to the use of a composition comprising aminoalcohol-modified polyorganosiloxanes to reduce corrosion on reinforcing steel of concrete structures, and to a method of reducing corrosion of reinforcing bars of concrete structures.

State of the art

Steel as a reinforcing agent in buildings is widely used. Of particular importance is reinforcing steel. The steel is introduced into a hydraulically setting material and reinforces this. The steel is used in particular strand-shaped, in particular as rods or grids, for use, and is often referred to by the skilled person as a reinforcing iron. Of particular importance is reinforced concrete. The corrosion of steel, which is present in hydraulically hardened materials, is of great economic importance. The corrosion of the steel core reduces its strength and thus the strength of the concrete. In addition, the corrosion products such as iron oxides or iron oxide hydrates have a larger volume than the non-corroded steel itself. As a result, create stresses in the concrete, which can lead to cracks or chipping of whole pieces. Concrete structures can be rehabilitated by superficially removing or blasting concrete and exposing the steel reinforcement. The steel reinforcement can then after removal of corrosion products, for example by sandblasting, with corrosion inhibitors or Treated corrosion-containing products and finally covered with concrete or a repair mortar, or reprofiled, are. This method is used mainly in cases of advanced corrosion of the reinforcing steel (in case of excessive cross-sectional loss this is to be replaced by new reinforcing steel) and concrete spalling, as well as presence of higher chloride concentrations in the steel reinforcement covering concrete layer. This procedure is very complicated and causes considerable costs.

It is known to add fresh concrete corrosion inhibitors, such as nitrites, amines, alkanolamines, their mixtures with inorganic or organic acids or phosphoric acid esters, or to treat surfaces of hardened reinforced concrete with a penetrating corrosion inhibitor. However, to be effective, the corrosion inhibitors must penetrate through the concrete to the steel insert. Depending on the thickness of the concrete cover, this can be a distance of several centimeters and the penetration takes a correspondingly long time. A considerable part of the applied amount of these corrosion inhibitors thus does not reach the steel insert at all and accordingly can not develop any corrosion-inhibiting effect. The inhibitors must therefore be used in large quantities, which makes many operations necessary, and is uneconomical. Furthermore, amino alcohols are very volatile and often very odor-intensive, which is disadvantageous both for the applications, in particular when dealing with large-area applications.

It is also known to prevent the penetration of water in reinforced concrete structures by suitable coatings based on silicon compounds and reaction resin coatings. EP-A-0 177 824 describes a hydrophobing agent of resinous organopolysiloxanes and organic solvents as well as layered silicates. However, such paints are hydrophobic, but not corrosion inhibiting, and have the disadvantage of being easily damaged, for example, by mechanical interference, UV rays or acid rain, which results in the chloride ions still penetrating the concrete over time can penetrate and lead to corrosion on the steel inserts. EP-A-1 308 428 describes an agent based on alkylalkoxysilane or alkylalkoxysiloxane for reducing the corrosion currents on steel reinforcements in concrete. In the silanes and siloxanes described, the Si atom is exclusively connected by Si-alkylene bridges, that is to say by a Si-C bond, with substituents carrying the amino function. For this purpose, a solution of the corrosion inhibitor is applied or sprayed onto the concrete surface several times in succession, the corrosion inhibitor penetrating the surface. However, such a composition contains only a low concentration of migratory corrosion inhibitor. In order to obtain the desired corrosion-inhibiting effect on the steel reinforcements, therefore, the composition must be applied in a very large amount and in a large number of operations, which is uneconomical and very labor-intensive. There is therefore a need to provide a composition for reinforced concrete that can be applied to existing concrete structures that protects against corrosion both quickly and for a long time, and that serves both to inhibit corrosion and to impregnate mineral building materials. In particular, there is a need for a composition which is stable on storage and with which a corrosion inhibitor can be applied in a high concentration to a concrete surface or introduced into a concrete mixture.

Presentation of the invention

The object of the present invention is therefore to provide compositions for the reduction of the corrosion of steel reinforcements, which overcome the disadvantages of the prior art. Surprisingly, it has been found that this object can be achieved by a use according to the independent claims. In addition, such compositions have excellent processability and high stability. These compositions containing polyorganosiloxanes have the great advantage of combining the properties of corrosion inhibition and hydrophobization. A concrete treated with it is treated on the surface, or in a layer on the surface, hydro- phobicized and on the other hand amino alcohol is split off, which penetrates into the concrete and protects the reinforcing steel from corrosion. In particular, it has been found that with this use at the same time strong hydrophobing takes place and in this way large amounts of amino alcohol can be introduced without causing precipitations of the siloxanes or silanes. Furthermore, these compositions allow the application of large quantities, without the application of large amounts of amino alcohols are released into the ambient air. This is not possible with the methods of the prior art. The method can thus be used both for the renovation of old concrete, as well as for the corrosion protection of reinforcing iron in fresh concrete.

Further advantageous embodiments of the invention will become apparent from the dependent claims.

Way to carry out the invention

The present invention relates to compositions and their use for reducing corrosion on steel reinforcements of steel structures.

The composition here contains at least one polyorganosiloxane S which has at least 4 repeat units of the general formula (I).

[A ¹ _z (B ¹ O) p SiO _(4- pz) / 2] (I)

B ¹ here represents either H, an alkyl or aryl radical having up to 18 C atoms or a radical of the general formula (II)

Furthermore, X ¹ and X ² independently of one another represent O, S or NR ⁴

A ¹ , R ² , R ³ and R ⁴ are each independently

Hydrogen or hydrocarbon radical containing up to 18 carbon atoms and may additionally contain heteroatoms which are selected from the group consisting of O, S, Si, Cl, F, Br, P and N.

Furthermore, R ⁵ , R ⁵ and R ⁶ independently of one another are an unbranched or branched alkylene radical having 1 to 8 C atoms. Further, z and p independently represent the values O, 1, 2 or 3. Further, m is 0 or an integer value of 1 to 10 and q is 0 or an integer value of 1 to 10.

In the polyorganosiloxane S is at least 1 radical of the general formula (II), at least one alkoxy or aryloxy having up to 18 carbon atoms and at least one repeat unit of the general formula (I) in which the silicon atom is bonded to 3 oxygen atoms present.

In all formulas of this document, the silicon atom is tetravalent and dashed lines symbolize the junctions with the other residues. If z, respectively p, is greater than 1, different ones can be used

Residues A ¹ , and B ^{1 be} present.

Compared to the amino-functional silanes and siloxanes of the prior art, in which the Si atom having an Si-C bond is bonded to the substituents carrying the amino function, the nitrogen-function-bearing radicals of the general formula (II) are attached to the silicon by an oxygen atom bound. This results in a dramatically altered reactivity of this bond, for example, in terms of hydrolyzability.

A ¹ may be hydrocarbon radicals, and are preferably aliphatic linear or branched or cycloaliphatic radicals or phenyl radicals. This preferably has 1 to 10, in particular 1 or 8 carbon atoms. Particularly preferred hydrocarbon radicals are phenyl, n-butyl, isobutyl, n-propyl, iso-propyl, ethyl, iso-octyl, n-octyl and methyl radicals. Particularly preferably, A ^{1 is} a hydrocarbon radical which is selected from the group consisting of the group methyl, n-octyl and iso-octyl. Also preferred hydrocarbon radicals A ¹ are radicals containing heteroatoms and may have functional groups selected from the group consisting of mercapto group, isocyanato group, wherein the isocyanato may be optionally blocked to protect against chemical reactions, hydroxy group, epoxy group, morpholino, piperazino, primary , secondary or tertiary amino groups having one or more nitrogen atoms, wherein the nitrogen atoms may be substituted by hydrogen or monovalent aromatic, aliphatic or cycloaliphatic hydrocarbon radicals, carboxylic acid group, carboxylic anhydride group, aldehyde group, urethane group, urea group, phosphonic acid monoester group, phosphonic acid diester group, phosphonic acid group, methacryloyloxy group, Acryloyloxy- group and mixtures thereof.

Also preferred hydrocarbon radicals A ¹ have the formula -OC (= O) -R ¹⁰ , wherein R ^{10 is} a monovalent linear or branched aliphatic or cycloaliphatic hydrocarbon radical or a monovalent aromatic hydrocarbon radical, preferably having 1 to 18, in particular 1 to 6 carbon atoms.

Preferred amino-containing radicals A ¹ have the general formula (V).

R ¹¹ here is a divalent to C-C hydrocarbon radical, in particular C ₂ -, C ₃ -, C ₄ -, C ₅ - or C ₆ -hydrocarbon radical, preferably a propylene radical, is.

R ¹² and R ¹³ independently of one another represent a hydrogen atom or an optionally fluorine-, chlorine- or bromine-substituted d- to C 18-

Hydrocarbon radical, preferably C ₂ -, C ₃ -, C ₄ -, C ₅ - or C ₆ -hydrocarbon radical, which optionally has cycloaliphatic or aromatic moieties. Furthermore, c stands for a value of 2, 3, 3, 5, or 6, in particular of 2, and d stands for 0 or a value of 1, 2, 3 or 4, in particular of 0 or 1.

B ¹ may be an alkyl or aryl radical. Preferred alkyl or aryl radicals are aliphatic, linear or branched or cycloaliphatic radicals or phenyloxy radicals bonded to the silicon atom via an oxygen atom. The radicals B ¹ preferably have 1 to 6, in particular 1 to 3 carbon atoms. Particularly preferred radicals B ¹ are ethyl or methyl. Furthermore, B ¹ may be a radical of the formula (II).

In a preferred embodiment, R ^{6 represents} an ethylene, propylene, isopropylene or -C (CH ₃ ) 2-CH ₂ - or a polyethylene or polypropylene. In particular, R ^{6 represents} an alkylene radical of the formula (III)

where n is an integer value of 1 to 10, in particular from 1 to 4. N is particularly preferably 2.

In a preferred embodiment of the invention, m = q = 0. In a further embodiment, R ² and / or R ^{3 are} methyl, ethyl, isopropyl, n-propyl, isobutyl, n-butyl, isopentyl, n-pentyl or linear or branched hexyl, heptyl or octyl. Particularly preferred are methyl, ethyl or n-butyl.

In a further preferred embodiment of the invention

R ² and / or R ^{3 is} H or a linear or branched aliphatic radical having 1 to 12 carbon atoms, in particular methyl, ethyl, n-propyl, iso-

Propyl, n-butyl, iso-butyl, sec-butyl or tert-butyl. Particularly preferred are methyl, ethyl or n-butyl.

In a further preferred embodiment of the invention, R ^{2 is} H and R ^{3 is} a linear or branched aliphatic radical having 1 to 12

Carbon atoms, in particular methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl or tert-butyl. Particularly preferred are methyl, ethyl or n-butyl. The at least 4 repeat units of the formula (I) may be the same or different, independently of each other, as long as the conditions formulated above for the polyorganosiloxane S are fulfilled.

The polyorganosiloxanes S may have, in addition to the 4 recurring units of the general formula (I), further siloxane repeating units. The further siloxane repeating units preferably contain radicals which are selected from the group consisting of hydrogen, hydroxyl, methyl and phenyl radicals.

Preferred polyorganosiloxanes S are those which contain at least 0.5 percent by weight, but not more than 60 percent by weight of radicals OB ¹ . Particularly preferred are those polyorganosiloxanes S containing at least 1 percent by weight, but not more than 50 percent by weight based on the weight of the polyorganosiloxane S radicals B ¹ . Preferably in the polyorganosiloxane S at least 70 mole percent, in particular at least 90 mole percent of the radicals B ¹ radicals of the general formula (II).

The molecular weights of the preferred polyorganosiloxanes S have a molecular weight average _Mw , which is from 500 to 5000, particularly preferably from 600 to 3500, g / mol.

The preferred polyorganosiloxanes S are at least 10 mol%, in particular at least 50 mol%, of so-called T units, where T units are those in which the Si atom is bonded to three oxygen atoms, irrespective of whether the oxygen atom links two Si atoms together or is part of a hydroxy, alkoxy or aryloxy radical OB ¹ .

The further repeating units are preferably D units or M units, that is to say those in which the Si atom is bonded to two oxygen atoms (D unit) or has a bond to only one oxygen atom (M unit).

The polyorganosiloxanes S can be obtained by a reaction of polyorganosiloxanes C containing hydrolyzable groups and which are composed of at least 4 repeat units of the general formula (VI)

[A ¹ _z (R ¹ ) p SiO _(4- pz) / 2] (VI) with an aminoalcohol of the formula (VII)

The radical R ¹ hereby means an alkoxy or aryloxy radical with up to

18 carbon atoms, a hydroxyl radical, H or via CH ₂ group bonded to Si, or phosphonic acid group, and Phosphonsäureesterrest

The radicals A ¹ , R ² , R ⁴ , R ⁵ , R ^{5 '} , R ⁶ , X ¹ , X ² , p, z, m and q have the above meanings. In the polyorganosiloxane C is at least one alkoxy or aryloxy having up to 18 carbon atoms and at least one repeat unit of the general formula (VI), in which the silicon atom is bonded to 3 oxygen atoms, but contrary to the polyorganosiloxane S, no radical of the general formula ( II) available. Examples of suitable amino alcohols of the formula (VII) are

one-sidedly amino-terminated polyoxyalkylenediols, in particular polyethylene glycols or polypropylene glycols

-einseitig alkoxylated polyoxyalkylene-polyamines, especially as obtained by unilateral alkoxylation of polyoxyalkylene polyamines which are obtainable for example under the trade name Jeffamine ^® from Huntsman Chemicals;

-einseitig alkoxylated polyethyleneimines, in particular as obtained by unilateral alkoxylation of polyethyleneimines, as obtainable for example under the trade name Lupasol ^® from BASF polyoxyalkylene polyamines;

Ammonia or primary amine or secondary amine initiated addition products of ethylene oxide and / or propylene oxide Ethanolamine (2-aminoethanol), 3-aminopropanol, 1-amino-2-propanol, 2-amino-1-propanol (alaninol), 4-amino-1-butanol, 2-amino-1-butanol, 2-amino 2-methyl-1-propanol, 2-amino-2-methyl-1-propanol (AMP) and their N-alkylated or N-dialkylated derivatives; -2- (2-aminoethoxy) ethanol and its N-alkylated or N-dialkylated derivatives;

Preferred primary amino alcohols are ethanolamine, 1-amino-2-propanol, 2-amino-1-propanol, 2-amino-2-methyl-propanol and 2- (2-aminoethoxy) ethanol.

Preferred secondary amino alcohols are N-methyl-ethanolamine, N-methyl-1-amino-2-propanol, N-methyl-2-amino-1-propanol, N-methyl-2- (2-aminoethoxy) -ethanol; N-ethyl-ethanolamine, N-ethyl-1-amino-2-propanol, N-ethyl-2-amino-1-propanol, N-ethyl-2- (2-aminoethoxy) -ethanol; N-butyl-ethanolamine, N-n-butyl-1-amino-2-propanol, N-n-butyl-2-amino-1-propanol, N-n-butyl-2- (2-aminoethoxy) -ethanol.

Preferred teritäary amino alcohols are N, N-dimethyl-ethanolamine, N, N-dimethyl-1-amino-2-propanol, N, N-dimethyl-2-amino-1-propanol, N, N-dimethyl-2- (2 -aminoethoxy) ethanol, N, N, N'-trimethyl-aminoethylethanolamine; N ₁ N-diethyl-ethanolamine, N, N-diethyl-1 -amino-2-propanol, N, N-diethyl-2-amino-1-propanol, N, N-diethyl-2- (2-aminoethoxy ) -ethanol, N, N, N'-triethyl-aminoethyl-ethanolamine; N, N-di-n-butylethanolamine, N, N-di-n-butyl-1-amino-2-propanol, N, N-di-n-butyl-2-amino-1-propanol, N, N-di-n-butyl-2- (2-aminoethoxy) -ethanol, N, N, N'-tri-n-butyl-aminoethylethanolamine, N, N, -Dibuytl-N'-methyl-aminoethyl-ethanolamine.

The polyorganosiloxanes C are compounds known to the person skilled in the art and can be prepared in a known manner, as described, for example, in Andreas Tomanek, "Silicones and Technology", ed. Wacker Chemie GmbH, Carl Hanser Verlag, Munich, 1990, pp. 24-25. is described.

The reaction of the polyorganosiloxane C with an aminoalcohol of the formula (VII) is preferably carried out as completely as possible, that is, in the Essentially as far as possible no unreacted amino alcohol is present in the reaction product. Typically, bases such as alkoxides are used for the reaction. Cleavage products formed during the reaction, such as, for example, alcohols, are preferably separated off from the reaction mixture by applying a vacuum, if appropriate at elevated temperature, in order to achieve as complete a conversion as possible.

The composition may consist only of the polyorganosiloxane S or contain other compounds. As preferred further constituents are, in particular, on the one hand

To call silanes and on the other hand hydraulically setting binders.

In one embodiment of the invention, in addition to the polyorganosiloxane S, the composition furthermore contains at least one organosilane of the formula (IV)

The radical R ⁷ here is H or an alkyl or aryl radical having up to 18 C atoms or a radical of the formula (II). The radical R ⁸ here is H or an alkyl or aryl radical having up to 18 C atoms and A ^{2 is} a radical as is possible for A ¹ . The radical A ² may be the same or different from A ¹ . Finally, a is a value of 0.1 or 2. If there are several radicals R ⁷ (ie a ≠ 2), these radicals can be identical or different, independently of one another.

Organosilanes in which A ^{2 is} an alkyl radical having 3 to 12 C atoms, in particular having 5 to 9 C atoms, are particularly suitable.

Further preferred are organosilanes in which R ^{7 represents} methyl or ethyl or a radical of the formula (II).

Particular preference is given to organosilanes in which a has a value of 0.

Preferred such silanes are pentyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, isooctyltrimethoxysilane, decyltrimethoxy silane and dodecyltrimethoxysilane, in particular octyltrimethoxysilane and iso-octyltrimethoxysilane and their ethoxy variants.

It has surprisingly been found that the penetration of the corrosion inhibitor is markedly improved by the addition of organosilanes, in particular those of the formula (IV), in particular with ethyl as R ⁷ , to polyorganosiloxanes. In particular, it has been shown that penetration is much faster. This is particularly advantageous when several wet-in-wet applications are performed. It also turns out that there is no or almost no discoloration or darkening of the treated concrete surface compared to the untreated surface. Thanks to the addition of organosilane, it is easy to adjust the concentration of polyorganosiloxane S, and thus the concentration of amino alcohol, which is split off upon penetration, to the particular needs of the application.

Organosilanes which have one or more radicals R ⁷ which are H or an alkyl or aryl radical having up to 18 C atoms are commercially widely available or can be readily prepared from the corresponding methoxy derivatives (ie R ⁷ = methyl), in particular by transesterification, produce. Preferred such silanes are pentyltrimethoxysilane, hexylthmethoxysilane, octyltrimethoxysilane, isooctylthymethoxysilane, decyltrimethoxysilane and dodecyltrimethoxysilane, in particular octyltrimethoxysilane and isooctylthymethoxysilane.

Organosilanes of the formula (IV) in which the radical R ^{7 is} a radical of

Formula (II) can be prepared by the same method as has already been described for the polyorganosiloxanes S. Typically, a transesterification of an alkoxyorganosilane (ie R ⁷ = alkyl, in particular methyl) is also reacted here with an aminoalcohol. Again, it is advantageous that the provided amino alcohol is implemented as fully as possible. Depending on the amount of aminoalcohol used, in the case of di- or trialkoxysilanes (a = 0 or 1), all alkyl groups or only a part of which are replaced by radicals of the formula (II). By way of example, the reaction products of octyltrimethoxysilane with aminoethanol may be mentioned here:

In a further embodiment of the invention, in addition to the polyorganosiloxane S, the composition also contains at least one hydraulically setting binder. The hydraulically setting binder is especially a mineral binder such as cement, gypsum, fly ash or slag, as well as additives. Preferred hydraulic binders comprise at least one cement, in particular at least one cement according to Euronorm EN 197 or calcium sulfate, in the form of anhydrite, hemihydrate or dihydrate gypsum; or calcium hydroxide. Portland cements, sulfoaluminate cements and high-alumina cements, in particular Portland cement, are preferred. Cements of cements can lead to particularly good properties. Cementitious rapid binders, which preferably contain at least one high-alumina cement or some other source of aluminate, such as, for example, aluminous clinker, and optionally, are used for rapid curing Calcium sulfate, in the form of anhydrite, hemihydrate or dihydrate gypsum; and / or calcium hydroxide.

The composition may range from low viscosity to high viscosity, i. pasty or gelatinous form. The composition is preferably low-viscosity and readily penetrable. The composition preferably has a viscosity of from 1 to 100 mPas, more preferably from 1 to 50 mPas, even more preferably from 1 to 20 mPas or from 5 to 10 mPas.

To improve the application properties, the composition can be formulated depending on the use as a low or high viscosity emulsion or solution. For example, the composition can be added as an aqueous emulsion or solution to the concrete mixing water to ensure the most homogeneous possible distribution. Particularly suitable for application to a reinforced concrete surface are compositions which are sufficiently viscous that they can be applied in a few operations, preferably in one operation, even on vertical surfaces in an amount of more than 100 g / m ² , in particular from 100 to 400 g / m ² . can be applied by drainage without major product losses.

Also, the composition may contain additional components such as solvents, dyes, luminescent agents, diluents, water, emulsifiers, thickeners, thixotropic agents, corrosion inhibitors or a mixture thereof. Particularly suitable solvents are alcohols, preferably methanol, ethanol, propanol, isopropanol, butanol, higher alcohols, such as ethylene glycol, glycerol, polyether polyols, such as polyethylene glycols and ether alcohols, such as butylglycol, methoxypropanol, and alkylpolyethylene glycols, but also aldehydes, esters, Ethers, amides or ketones, in particular acetone, methyl ethyl ketone, hydrocarbons, in particular methyl esters, ethyl esters, isopropyl esters, heptane, cyclohexane, xylene, toluene, white spirit and mixtures thereof. As thickening aids are, for example, fine-grained clay minerals, precipitated silica or fumed silica suitable. Particularly suitable corrosion inhibitors are amino alcohols, in particular those of the formula (VII).

It has surprisingly been found that the composition described above is perfectly suitable for application to concrete surfaces, and which penetrates well into those concrete layers in which the steel reinforcements are usually present. Thus, such a composition is well suited to reduce or prevent corrosion of the steel reinforcement.

The present invention therefore relates to the use of the described composition for reducing corrosion on steel reinforcements of reinforced concrete structures.

In a further aspect, the invention relates to a method for reducing or reducing corrosion on steel reinforcements of reinforced concrete structures, wherein the composition is preferably applied to a reinforced concrete surface.

The application of the composition can advantageously be done by spraying, brushing, spraying, pouring, brushing or rolling and as needed a tool such as brush, airless spray, Druckspeichersprühgerät, paint roller, spray can or the like can be used. In this case, the composition is in an amount of 50 to 2000 g / m ² , preferably from 100 to 1000 g / m ² , more preferably from 150 to 500 g / m ^2, most preferably from 200 to 300 g / m ² to the reinforced concrete surface applied. Optionally, the composition is applied in multiple layers, preferably in two, three or four layers, especially if the desired amount of active agent can not be applied in a single operation due to low absorbency of the substrate or the nature of the composition. In the case of multiple application, a drying time between operations may be required, the drying time being between minutes to several days, preferably between half an hour to 24 hours, more preferably between 1 and 12 hours, most preferably between 2 and 5 hours. In a further embodiment, the present invention comprises a process wherein the composition is added to the fresh concrete, ie a concrete that has not set yet. In this case, the composition is preferably added to the mixing water of the concrete. In this case, the composition is preferably added in an amount of 0.2 to 10 wt .-%, preferably 0.5 to 5 wt .-%, more preferably 1 to 3 wt .-% based on the weight of the cement mixture.

The present invention therefore also provides a hydraulically setting composition comprising the composition described above, a hydraulic binder, in particular a mineral binder such as cement, gypsum, fly ash or slag, and additives. Preferred hydraulic binders comprise at least one cement, in particular at least one cement according to Euronorm EN 197 or calcium sulfate, in the form of anhydrite, hemihydrate or dihydrate gypsum; or calcium hydroxide. Preference is given to Portland cements, sulfo-aluminate cements and high-alumina cements, in particular Portland cement. Cements of cements can lead to particularly good properties. Cementitious quick-release agents are preferably used for rapid curing, which preferably comprise at least one high-alumina cement or other aluminate source, such as, for example, aluminum-donating clinker, and optionally calcium sulfate, in the form of anhydrite, hemihydrate or dihydrate gypsum; and / or calcium hydroxide. As additive any liquid or powdered concrete admixtures can be used. Advantageous is the use of accelerators, condensers, thickeners, retarders, shrinkage reducers, defoamers, etc. Such additives, such as solidification accelerator or condenser, etc. are well known. Particularly important for the spraying of concrete are accelerators which are sold by Sika Schweiz AG, for example under the trade name Sigunit®. For example, those which are sold by Sika Schweiz AG under the trade name Sika® ViscoCrete® can be used as the plasticizer or retarder. Another object of the present invention is a against

Corrosion of steel reinforcement protected concrete structure, which has been treated by a process according to the invention. The concrete structure is advantageously a building of civil engineering, in particular a building or tunnel, a road or a bridge.

The polyorganosiloxane S can split off amino alcohol. When the described composition is applied to concrete, the polyorganosiloxane penetrates into the concrete. By hydrolysis, the polyorganosiloxane S separates amino alcohol and can undergo condensation reactions. As a result, a hydrophobic layer forms on the surface, in particular in a surface layer of the concrete. The aminoalcohol formed can in turn continue to penetrate into the concrete, so that it is possible to reach reinforcing iron, which are deeper, and to protect against corrosion. It is thus possible with the described method to simultaneously render reinforcing concrete hydrophobic on the surface and to protect reinforcing steel from corrosion.

Finally, compositions containing polyorganosiloxane S, as compared to compositions containing the corresponding aminoalcohol in the corresponding concentration, also have working toxicological and transport advantages, which may result in a more advantageous classification. During application, less volatile amino alcohols are released into the ambient air. This also leads to the particular advantage that the odor load during application is massively reduced. Examples

1. Compositions

The production of exemplary compositions containing polyorganosiloxanes S and / or comparative examples is described below. All percentages are by weight. Unless otherwise stated, all manipulations are carried out at room temperature of 23 ° C and under normal pressure (1013 mbar (abs.)). The devices are commercially available laboratory equipment as they are commercially available from numerous equipment manufacturers.

Example 1: 1

Reaction of an isooctylmethylsilicone resin, having a molecular weight average Mw of 1200 and containing 18% methoxy groups, with trimethylaminoethylethanolamine:

600.00 g of the silicone resin and 1122.88 g of trimethylaminoethylethanolamine are mixed in a 2 liter three-necked flask under nitrogen purge. The apparatus further comprises a reflux condenser and an internal thermometer. To the mixture is added 0.86 g of sodium methylate. The mixture is heated until reflux forms (112 ° C internal temperature). It is refluxed for 1 h. Thereafter, the mixture is cooled and exchanged the reflux condenser for a distillation bridge. The mixture is distilled for 3 hours under normal pressure, whereby the internal temperature increases to 135 ° C. Thereafter, a vacuum of 60 mbar and distilled for a further 2 hours under vacuum. This gives a slightly yellowish, clear, slightly viscous liquid with a slight odor.

Yield: 634 g, viscosity: about 100 mPa * s (Brookfield viscometer (RVT), rotational viscometer with defined velocity gradient, spindle No.3, based on DIN EN ISO 3219). The liquid has remained stable over the entire storage period observed. Characterization ( ¹ H-NMR):

MeSiO 3/2 37.2 mol% 21, 7 wt% i-octyl-SiO 3/2 10.5 mol% 15.1 wt%

MeOSi 0.11 mol% 0.02 wt%

(CH _g) ₂ NCH ₂ CH ₂ N (CH ₃₎ CH ₂ CH ₂ OSi 42.3 mol% 50.5 wt .-%

Trimethylaminoethylethanolamine 9.88 mol% 12.6 wt.%

Example 2: 2

Reaction of an isooctylmethylsilicone resin, with a molecular weight average Mw of 1200, which has 18% methoxy groups, with N-methylethanolamine:

254.94 g of the silicone resin are mixed with 245.06 g of N-methylethanolamine and added 0.25 g of sodium methylate. The preparation of the mixture is carried out under nitrogen purge. The mixture is prepared in the 1 l one-necked round bottom flask of a rotary evaporator. The charged flask is attached to a rotary evaporator. At the beginning, a vacuum of 300 mbar is applied and the oil bath is then heated to 110 ^° C. If the oil bath temperature of 110 ⁰ C is reached, the vacuum is carefully lowered to 60 mbar. To keep the distillation alive, the bath temperature is raised to 140 ° C over 2 hours. After 2 hours no more distillate passes. This gives 305.87 g of a yellowish orange colored, clear, slightly viscous liquid with a low odor. Viscosity: approx. 100 mPa * s (Brookfield viscometer (RVT), rotational viscometer with defined velocity gradient, spindle No.3, based on DIN EN ISO 3219). The liquid has remained stable over the entire storage period observed.

Characterization ( ¹ H-NMR):

MeSiO3 / 2 40.0 mol% 34.4 wt% i-octyl-SiO3 / 2 11, 7 mol% 24.8 wt%

MeOSi 0.59 mol% 0.17 wt%

CH ₃ NHCH ₂ CH ₂ OSi 45.9 mol% 38.9 wt.%

CH ₃ NHCH ₂ CH ₂ OH 1, 69 mol% 1, 63% by weight

MeOH 0.01 mol% 0.01 wt% Example 3: 3

Reaction of an isooctylmethylsilicone resin, having a molecular weight Mw of 1200 and containing 18% methoxy groups, with N-butylethanolamine:

266.70 g of the silicone resin are mixed with 400.00 g of N-butylethanolamine and 0.33 g of sodium methylate was added. The preparation of the mixture is carried out under nitrogen purge. The mixture is prepared in the 1 l one-necked round bottom flask of a rotary evaporator. The charged piston is attached to the rotary evaporator. At the beginning, a vacuum of 300 mbar is applied and the oil bath is then heated to 110 ^° C. If the oil bath temperature of 110 ⁰ C is reached, the vacuum is carefully lowered to 60 mbar. To keep the distillation alive, the bath temperature is raised to 140 ° C over 2 hours. After about 2 hours no more distillate passes. This gives 406.26 g of a yellowish, clear, slightly viscous liquid with a slight odor. Viscosity: approx. 150 mPa * s (Brookfield viscometer (RVT), rotational viscometer with defined velocity gradient, spindle No.3, based on DIN EN ISO 3219). The liquid has remained stable over the entire storage period observed.

Characterization ( ¹ H-NMR):

MeSiO3 / 2 32.8 mol% 21, 6 wt% i-octyl-SiO3 / 2 9.2 mol% 14.9 wt%

MeOSi 0.03 mol% 0.01 wt%

CH ₃ (CH ₂ ) ₃ NHCH ₂ CH ₂ OSi 35.9 mol% 38.1 wt%

CH ₃ (CH ₂ ) ₃ NHCH ₂ CH ₂ OH 22.1 mol% 25.4 wt%

MeOH 0 mol% 0 wt%

Example 4: 4

A mixture of 50% by weight of Example 3 and 50% by weight of isooctyltrimethoxysilane by pouring together the two liquid produced. The liquid has remained stable over the entire storage period observed.

Example 5: 5 A mixture of 66.6% by weight of Example 3 and 33.3

Wt .-% iso-octyltrimethoxysilane prepared by pouring together the two liquids. The mixture has a low odor. The liquid has remained stable over the entire storage period observed.

Example 6: 6

A mixture of 66.6% by weight of Example 2 and 33.3% by weight of isooctyltrimethoxysilane was prepared by pouring together the two liquids. The mixture has a low odor. The liquid has remained stable over the entire storage period observed.

Example 7: 7

A mixture of 66.6% by weight of Example 1 and 33.3% by weight of isooctyltrimethoxysilane was prepared by pouring the two liquids together. The mixture has a low odor. The liquid has remained stable over the entire storage period observed.

Example 8: 8

A mixture of 50% by weight of Example 2 and 50% by weight of dipropylene glycol monomethyl ether was prepared by pouring together the two liquids. The mixture has a low odor. The liquid has remained stable over the entire storage period observed.

Example 9: 9

A mixture of 55.6% by weight of Example 2 and 44.4% by weight of dipropylene glycol monomethyl ether was prepared by pouring together the two liquids. The mixture has a low odor. The liquid has remained stable over the entire storage period observed.

Reference Example 1 Ref. 100% by weight of isooctyltrimethoxysilane. Reference Example 2 Ref.2

It was a mixture of 98.49 wt .-% iso-octyltrimethoxysilane and 1.51 wt .-% N-n-butylethanolamine by pouring together the two

Made liquids. The mixture has a significant odor. The liquid has remained stable over the entire storage period observed.

Reference Example 3 Ref.3

A mixture of 66.6 wt% iso-octyltrimethoxysilane and 33.3 wt% N-n-butylethanolamine (stoichiometric, i.e., 50 mol%: 50 mol%) was prepared by pouring together the two liquids. The mixture has a very strong odor.

Reference Example 4 Ref

Protectosil® CIT, commercially available from Degussa.

2. Application attempts

The compositions were applied to 3 year old concrete slabs using a brush in the amount shown in Tables 1 and 2. For the production of the concrete slabs a concrete was used which was produced using the following and water: 11.25 kg Portland cement PC CEM I 42.5 according to standard EN 197-1 0.75 kg limestone filler 24 kg sand 0 - 1.2 mm 15 kg sand 1.2 - 4.0 mm 11.25 kg Sand 4.0 - 8.0 mm 24 kg Sand 8.0 - 16.0 mm

No concrete admixtures were used. The water / cement value (w / c value) was 0.64, the slump measured according to the standard EN

12350-5 (1999) 45 cm, the water conductivity q _w measured according to the norm

SIA 162/1 A (2003) 3.8 g / m ² h, the water absorption coefficient w, measured according to the standard DIN 52617 (mod. 1996) 720 +/- 80g / m ² h ^{0 5} and the air pores Content measured according to standard EN 12350-7 (2000) 3.6%. There are concrete slabs produced in the sizes of 300x300x80 mm, 28 days at 20 ⁰ C and 95% relative humidity and then stored for weather-exposed. The compressive strength after 28 days was 30.9 MPa. Prior to application of the compositions, the plates were sawn in two halves of the size 300x148x80 mm. After rinsing with water, the plate-like specimens thus obtained were conditioned for about 2 weeks in a climatic chamber at 23 ° C and 50% relative humidity.

After applying the corrosion-inhibiting composition to the concrete sample plates, the samples were stored for weather-exposed on a flat roof surface for one month and then the

Discoloration of the concrete slabs, the beading effect, as well as the penetration of the

Composition analyzed.

Surface hydrophobing: beading effect

The beading effect of dripped water was evaluated by measuring the contact angle or contact angle. Large contact angles of more than 90 ° indicate good bead-off effects, average to small contact angles of less than 90 ° rather indicate poor bead-off effects (Table 1).

Hydrophobization: Intrinsic behavior

The penetration behavior of the hydrophobic compounds was determined by determining the thickness of the hydrophobic zone at the surface. After removal of a core (75mm core bit) and drying of the wall of the hole in the concrete slab, the wall was wetted by means of water. The boundary line from wetting to non-wetting by water was clearly visible. The thickness of the non-wetted hydrophobic zone on the surface indicates the penetration depth of the hydrophobic compounds. With the penetration depth, the water absorption of the concrete decreases while increasing its hydrophobicity.

Table 1: Determination of hydrophobic zone and beading effect. ^* unchanged = unchanged

Intrinsic behavior of the corrosion inhibitor: Amino alcohol detection by Ninhvdrin color reaction

The penetration behavior of the corrosion inhibitor was determined by determining the depth profile, i. by determining the amino alcohol concentrations in different concrete layers of the sample plates, i. a depth of 0-8mm, 11-19mm, 22-30mm, 33-41mm, and 44-52mm, analyzed by ninhydrin color reaction (Table 2).

The ninhydrin color reaction was carried out as follows: 1 g of crushed concrete sample from different layers of the concrete sample plate was weighed into a pilling glass, admixed with 1 ml of distilled water, shaken well and left for 30 min. ditched. The liquid was filtered through a 0.45 μm membrane filter. The extract was prepared in an oven at 120 ⁰ C for 2 h activated TLC plate (TLC finished plates silica gel 60 F ₂ 54, 20x20cm, Merck Art. No. 105735) was applied to 10 ul in several portions. In between was dried with a hair dryer. After brief drying, the TLC plate was sprayed completely with a spray solution consisting of 0.15 g ninhydrin in 50 ml butanol and 1.5 ml glacial acetic acid (Merck reagent 231) and after further brief drying with a spray solution consisting of 0.1 g ninhydrin in 50 ml ethanol (Merck reagent 231 ) sprayed. Subsequently, the TLC plate was developed for about 1 h at 120 ⁰ C in a drying oven until the evaluation. The identification help became a standard solution. (100ng monoethanolamine / 10μl H ₂ O) and a blank (distilled water) with applied. A red spot on an orange background means that alkanolamine was detected in the sample layer. At the blank value finds no color reaction taking place. The red color was subdivided into "very intense", "intense", "medium", "light", "trace" and "undetectable" according to the intensity of the coloration. In Table 2 the codes are given: Very intensive: 5 intensive: 4 medium: 3 easy: 2

Track: 1 n.n .: undetectable

Of particular interest is the amino alcohol detection at a depth of 22-30 mm, where usually the steel reinforcement is located.

The results of Table 2 show that Reference Examples Ref. 1 to Ref. 4 can introduce no or only minimal amounts of aminoalcohols into the concrete. Examples 1 to 9 have a lower odor than the reference examples. In particular, Reference Example Ref.3 with an increased concentration of aminoalcohol has a dramatic difference in odor and volatility compared to Examples 1-9. It has been shown that the examples with polyorganosiloxane S and an organosilane (Examples 4 to 7) show an extremely good penetration behavior.

Of course, the invention is not limited to the embodiments shown and described. It is understood that the abovementioned features of the invention not only in the combination specified, but also in other modifications,

Combinations and modifications or alone can be used without departing from the scope of the invention.

K)

Table 2: Depth profile analysis (amino alcohol detection) by ninhydrin color reaction. after application.

Claims

claims

Use of a composition for reducing corrosion on steel reinforcements of reinforced concrete structures, said composition comprising at least one polyorganosiloxane S having at least 4 repeat units of the general formula (I)

[A ¹ _z (B ¹ O) _p SiO (4-pz) / 2] (I)

wherein B ^{1 is} either H, an alkyl or aryl radical having up to 18 carbon atoms or a radical of the general formula (II)

and wherein X ¹ and X ² independently represent O, S or NR ⁴ ;

A ¹ , R ² , R ³ and R ⁴ independently represent a hydrogen or

Hydrocarbon radical containing up to 18 carbon atoms and in addition

May contain heteroatoms selected from the group consisting of O, S, Si, Cl, F, Br, P and N;

R ⁵ , R ⁵ and R ⁶ independently of one another represent an unbranched or branched alkylene radical having 1 to 8 C atoms; z and p independently of one another represent the values 0, 1, 2 or 3; m is 0 or an integer value of 1 to 10; q is 0 or an integer from 1 to 10;

with the proviso that in the polyorganosiloxane S at least 1 radical of the general formula (II), and at least one alkoxy or aryloxy having up to 18 carbon atoms, and at least one repeat unit of the general formula (I), wherein the silicon atom to 3 Oxygen atoms is bound, are present.

2. Use according to claim 1, characterized in that R ^{6 is} an alkylene radical of the formula (III)

where n is an integer value of 1 to 10.

3. Use according to claim 2, characterized in that n is 2.

4. Use according to one of the preceding claims, characterized in that R ² and / or R ^{3 is} H or a linear or branched aliphatic radical having 1 to 12 carbon atoms, in particular methyl, ethyl, n-propyl, iso-propyl, n Butyl, iso-butyl, sec-butyl or tert-butyl, preferably methyl, ethyl or n-butyl.

5. Use according to claim 4, characterized in that R ^{2 is} H and R ^{3 is} a linear or branched aliphatic radical having 1 to 12

Carbon atoms, in particular methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl or tert-butyl, preferably methyl, ethyl or n-butyl.

6. Use according to one of the preceding claims, characterized in that A ^{1 is} a hydrocarbon radical, in particular a hydrocarbon radical which is selected from the group consisting of methyl, n-octyl and iso-octyl.

7. Use according to one of the preceding claims, characterized in that the polyorganosiloxane S to at least 50 mol% of so-called T units are constructed, wherein T units are those in which the Si atom is bonded to three oxygen atoms.

8. Use according to one of the preceding claims, characterized in that the proportion of the radicals OB ¹ in the polyorganosiloxane S is 10 to 50% by weight.

9. Use according to one of the preceding claims, characterized in that in the polyorganosiloxane S at least 70 mole percent of the radicals B ^{1 are} radicals of the general formula (II).

10. Use according to one of the preceding claims, characterized in that the composition further comprises at least one

Organosilane of formula (IV) contains

wherein R ^{7 is} H or an alkyl or aryl radical having up to 18 C atoms or a radical of the formula (II);

R ^{8 is} H or an alkyl or aryl radical having up to 18 C atoms; A ^{2 is} a radical as is possible for A ¹ ; and a is a value of 0.1 or 2.

11.Use according to claim 10, characterized in that A ² for g

XR ---, where R ^{9 is} a divalent organic radical, optionally

Heteroatoms selected from the group consisting of O, S, N and P;

X is H or a functional group selected from the group consisting of hydroxyl, epoxy, mercapto, amino, urethane, carboxyl aldehyde, (meth) acryloyloxy, stands.

12. Use according to one of the preceding claims, characterized in that the composition further contains at least one hydraulically setting binder.

13. Use according to any one of claims 1 to 12, characterized in that the composition is applied to a reinforced concrete surface.

H.Use according to one of claims 1 to 12, characterized in that the composition is applied to Stahlarmierungen.

15. Use according to any one of claims 1 to 12, characterized in that the composition is added to fresh concrete.

16. Method of reducing corrosion on steel reinforcements of

Reinforced concrete structures, characterized in that a composition, as used in the use according to one of

Claims 1 to 12 is applied to a reinforced concrete surface.

17. The method according to claim 16, characterized in that the composition is applied in several layers on the reinforced concrete surface.

18. The method according to any one of claims 16 or 17, characterized in that the composition is applied with a brush or paint roller on the reinforced concrete surface, sprayed or sprayed.

19. The method according to any one of claims 16 to 18, characterized in that the composition in an amount of 50 to 2000 g / m ² , preferably from 100-1000 g / m ² , more preferably from 200-500 g / m ² am most preferably from 250 to 300 g / m ^{2 is} applied to the reinforced concrete surface.

20. Concrete construction treated by a method according to one of claims 16 to 19.

21. Concrete construction according to claim 20, characterized in that the concrete structure is a building of civil engineering, in particular a building, a road, a bridge or a tunnel.