| Publication number | WO2010072641 A1 |
| Publication type | Application |
| Application number | PCT/EP2009/067359 |
| Publication date | Jul 1, 2010 |
| Filing date | Dec 17, 2009 |
| Priority date | Dec 22, 2008 |
| Also published as | CN102264665A, 5 More » |
| Inventors | Dimitrios Moussios, Mohammed Sanaobar, Jürgen BEZLER |
| Applicant | Wacker Chemie Ag |
| Export Citation | BiBTeX, EndNote, RefMan |
ABSTRACT
The invention provides hydraulically setting sealing composition based on a) a hydraulically setting compound out of the group comprising high-alumina cement, ordinary portland cement, blast furnace slag, b) protective-colloide stabilized polymer of one or more ethylenically unsaturated monomers in form of an aqueous polymer dispersion or a water-redispersible polymer powder, and c) one or more fillers.
CLAIMS (OCR text may contain errors)
1. Hydraulically setting sealing composition based on a) a hydraulically setting compound out of the group comprising high-alumina cement, ordinary portland cement, blast furnace slag, b) protective-colloide stabilized polymer of one or more ethylenically unsaturated monomers in form of an aqueous polymer dispersion or a water-redispersible polymer pow- der, and c) one or more fillers.
2. The cementitious sealing composition as claimed in claim 1 comprisinq a combination of high-alumina cement and blast furnace slag.
3. The cementitious sealing composition as claimed in claim 1 comprising ordinary portland cement as the only component a) .
4. The cementitious sealing composition as claimed in claim 1 comprising blast furnace slag as the only component a) .
5. The cementitious sealing composition as claimed in claims 1 to 4 , wherein polymers b} used are vinyl acetate ho- mopolymers, copolymers of vinyl acetate with ethylene, copolymers of vinyl acetate with ethylene and with one or more other vinyl esters, copolymers of vinyl acetate with ethylene and (meth) acrylic ester, copolymers of vinyl ace- tate with (meth) acrylates and other vinyl esters, copolymers of vinyl acetate with ethylene and vinyl chloride, copolymers of vinyl acetate with acrylates , styrene- acrylic ester copolymers, styrene-1, 3 -butadiene copolymers, vinyl chloride-ethylene-copolymers ,
6. The use of the cementitious sealing composition as claimed in any of claims 1 to S as a coating for the protection of concrete materials.
7. The use of the cementitious sealing composition as claimed in claim 6 as a salt resistant coating for concrete structures which are exposed to seawater.
DESCRIPTION (OCR text may contain errors)
Hydraulically Setting Sealing Composition
The present invention concerns hydraulically setting sealing compositions for the protection of concrete structures.
Accelerated detoriation of reinforced concrete structures is a well reported phenomenon. It occurs particulary in regions with aggressive environment. An example for such regions are the coastal areas of the Arabian Gulf. The environmental conditions of the Arabian Gulf are characterized by high temperature and humidity. Due to the closed nature of the Arabian Gulf, the salinity of the seawater is more than that in other areas of the world. The same is right for the salt concentra- tion in the air, particulary in costal regions. Such climatic effects reduces significantly the durability of concrete structures as well on shore as offshore.
Coppola L. et al , American Concrete Institute, SP (2000) , SP- 192-73, p, 1209-1220 describe the use of sealing slurries for the protection of concrete structures. The sealing slurries are composed of an acrylic polymer emulsion, cement and meta- kaolin. In JP 09-087061 a composition for coating concrete structures is recommended, composed of a vinyl acetate ethyl - ene copolymer emulsion, which is stabilized with nonioniσ emulsifier, alumina cement and silica sand. JP 03-039387 refers to a protection material for concrete composed of a polymer latex, alumina cement, transition metal oxide, iron oxide and sand. For the protection of corrosion on a surface con- tacted with seawater JP 55-121869 recommends a double-layered coating, with a first layer built with a mixture composed of aqueous polymer emulsion, portland cement or blast furnace cement, and a topcoat composed of copper sulphate and an aqueous polymer emulsion.
DE 3048818 Al describes the improvement of concrete structures with polymer latex compositions containing waxy additives. Concrete modified with these latex compositions shows an im- proved corrosion resistance in contact with salt water. The coating of concrete structures with a curable polymer resin is the subject of DE 3445396 Al. WO 86/04889 Al concerns the utilization of compositions based on polymer latex, aluminous cement and gypsum for obtaining crack- free concrete compositions with low water-permeability. US 4668541 B describes a method for protecting concrete structures against damages caused by chloride-initiated corrosion. The method is characterized in that a layer of slag-cement concrete is applied to the concrete structure. The patent US 4894405 is related to a coating composition formed by a polyurethane component and and an organosiloxane component. The main objective is to stop corrosion generated by chlorine ions .
It is an object of the invention to protect concrete structures even if exposed in harmful environment, like marine or splash zone environment where the conditions are severely corrosive. The surface of the concrete structures shall be protected against mechanical erosion due to wind (sand storms) or pounding waves , too .
This object has surprisingly been able to be achieved by the inventive combination of hydraulically setting components with a polymer component .
The invention provides hydraulically setting sealing composition based on a) a hydraulically setting compound out of the group comprising high-alumina cement, ordinary portland cement, blast furnace slag, b) protective-colloide stabilized polymer of one or more ethylenically unsaturated monomers in form of an aqueous polymer dispersion or a water-redispersible polymer powder, and c) one or more fillers.
In general the composition contains from 5 % by weight to 50 % by weight of component a) , preferably 5 % by weight to 25 % by weight, in each case based on the total weight of the dry materials a) to c) .
Component a) comprises high-alumina cement or ordinary port- land cement or blast furnace slag. Prefered high-alumina cement is calcium aluminate cement (CAC) according to DIN EN 14647. Prefered ordinary portland cement is ordinary portland cement (OPC) according to DIN EN 197-1 (CBM I to CEM V) . In general blast furnace slag contains 30 to 45 % by weight CaO, 30 to 45 % by weight SiO2, 5 to 15 % by weight Al2O3, 4 to 17 % by weight MgO, 0,5 to 1 % by weight S and traces of further elements. Commercially available blast furnace slag is Slag- starR of Baumit or Merit 5000 of SSAB Merox.
In a prefered embodiment the components a) are used alternatively in the composition. Particulary prefered as the only component a) is blast furnace slag. Prefered combinations of components a) are the combination of high-alumina cement with blast furnace slag, or the combination of ordinary portland cement with blast furnace slag. If couϊbinations are used in the composition, the composition contains from 5 % by weight to 50 % by weight of the combination, preferably 5 % by weight to 25 % by weight, in each case based on the total weight of the dry materials a) to c) ,
In general the composition contains from 10 % by weight to 50 % by weight, preferably from 10 % by weight to 30 % by weight of the polymer b) , in each case based on the total weight of the components a) to c) . In the case of polymer dispersions the amount in % by weight refers to the solids content of the polymer dispersions.
Preferably the aqueous polymer dispersion or the water- redispersible polymer powder is based on polymers of one or more monomers from the group consisting of vinyl esters,
(raeth) acrylates, vinyl aromatics, olefins, I1 3-dienes and vinyl halideε and, if required, further monomers copolymer!z- able therewith. Examples of suitable homo- and copolymers are vinyl acetate homopolymars , copolymers of vinyl acetate with ethylene, copolymers of vinyl acetate with ethylene and with one or more other vinyl esters, copolymers of vinyl acetate with ethylene and (meth) acrylic ester, copolymers of vinyl acetate with (meth) acrylates and other vinyl esters, copolymers of vinyl acetate with ethylene and vinyl chloride, copolymers of vinyl acetate with acrylates, styrene-acrylic ester copolymers, sty- rene-1, 3 -butadiene copolymers, vinyl chloride-ethylene- copolymers .
Preference is given to vinyl acetate homopolymers; Copolymers of vinyl acetate with from 1 to 40% by weight of ethylene;
Copolymers of vinyl acetate with from 1 to 40% by weight of ethylene and from 1 to 50% by weight of one or more other co- monomers from the group of vinyl esters having from 1 to 15 carbon atoms in the carboxylic acid radical, e.g. vinyl propi- onate, vinyl laurate, vinyl esters of alpha-branched carboxylic acids having from 9 to 13 carbon atoms {versatic acids) , such as VeoVa9, VeoValO, VeoVall;
Copolymers of vinyl acetate, from 1 to 40% by weight of ethylene, and preferably from 1 to 60% by weight of {meth) acrylic ester of unbranched or branched alcohols having from 1 to 15 carbon atoms, in particular N-butyl acrylate or 2-ethylhexyl acrylate; and
Copolymers using from 30 to 75% by weight of vinyl acetate, from 1 to 30% by weight of vinyl laurate or vinyl esters of an alpha-branched carboxylic acid having from 9 to 13 carbon atoms, and also from 1 to 30% by weight of (meth) acrylic esters of unbranched or branched alcohols having from 1 to 15 carbon atoms, in particular n»butyl acrylate or 2 -ethyl hexyl acrylate, where these also contain from 1 to 40% by weight of eth- ylene,-
Copolymers using vinyl acetate, from 1. to 40% by weight of ethylene, and from 1 to 60% by weight of vinyl chloride,- where the % by weight data in each case give a total of 100% by weight .
Preference is also given to (meth) acrylate copolymers, for ex- ample copolymers of n-butyl acrylate or 2-ethylhexyl acrylate, or copolymers of methyl methacrylate with n-butyl acrylate and/or 2-ethylhexyl acrylate;
Styrene-acrylic ester copolymers using one or more monomers from the group of methyl acrylate, ethyl acrylate, propyl acrylate, n~butyl acrylate, 2-ethylhexyl acrylate;
Vinyl acetate-acrylic ester copolymers using one or more monomers from the group of methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and, where appropriate, ethylene,- Styrene-1, 3 -butadiene copolymers; Vinyl chloride-ethylene copolymers ; where the % by weight data in each case give a total of 100 % by weight .
Aqueous polymer dispersions and the water-redispersible powders of the abovementioned polymers that are obtainable from them by drying are known and are available commercially. The polymers are prepared in a conventional manner, preferably by the emulsion polymerization process. Processes for the prepa- ration of aqueous polymer dispersions and redispersible polymer powders are described in WO 2004/092094, which is incorporated here by reference.
The dispersions are stabilized with a protective colloid. Sui- table protective colloids are partially hydrolyzed or fully hydrolyzed polyvinyl alcohols,- polyvinylpyrrolidones; polyvi- nylacetals; polysaccharides in water-soluble form such as starches (amylose and amylopectin) , celluloses and their car- boxymethyl, methyl, hydroxyethyl , and hydroxypropyl deriva- tives,- proteins such as casein or caseinate, soya protein, and gelatin; lignin sulfonates; synthetic polymers such as poly (meth) acrylic acid, copolymers of (meth) acrylates with car- boxy- functional comonomer units, poly (meth) acrylamide, polyvi- nylsulfonic acids, and the water-soluble copolymers thereof; melamine-formaldehyde sulfonates, napthaline- formaldehyde sulfonates, and styrene-raaleic acid and vinyl ether-maleic acid copolymers. Partially hydrolyzed or fully hydrolyzed polyvinyl alcohols are preferred. Particular preference is given to partially hydrolyzed polyvinyl alcohols having a degree of hydrolysis of from 80 to 95 mol% and a Hόppler viscosity in 4% strength aqueous solution of from 1 to 30 mPas (Hδppler method at 2O0C, DIN 53015) . Most prefered are polymer compositions without emulsifier.
Suitable fillers c) are quartz sand, quarts flour, calcium carbonate, dolomite, aluminum silicates, fumed silica, talc or mica, fibers, or lightweight fillers such as pumice, foamed glass, aerated concrete, perlites or vermiculites . Mixtures of said fillers may also be used. The filler fraction is preferably from 10 to 90 % by weight, with particular preference from 75 to 90 % by weight, in each case based on the total weight of the components a) to c) .
The sealing compositions may contain further common ingredients out of the group of pozzolanic compounds, thickener, re- tardants .
Most prefered further ingredients are additives having poz~ zolanic properties (pozzolanas) . Pozzolanas are silica- containing or silica- and alumina- containing natural or synthetic materials which are not themselves able to act as binders but together with water and lime form water- insoluble com- pounds having cement -like properties. A distinction is made between natural and synthetic pozzolanas. Natural pozzolanas include glass-rich ashes and rocks of volcanic origin, for example pumice, trass {finely milled tuff), Santorin earth, kie- selguhr, hornstones (silica rocks) , chert and moler earth. Synthetic pozzolanas include fired, ground clay {ground brick) , fly ashes such as ash from a coal- fired power station, silica dust, oil shale ash {oil shale = bituminous, lime- containing shale) and calcined kaolin (metakaolin) . The synthetic pozzolanas are preferably selected from the group consisting of ground brick, fly ash, silica dust, oil shale ash and metakaolin. The greatest preference is given to fly ash or silica dust . The amount used is from 0 to 20 % by weight, preferably from 0,5 to 10 % by weight, in each case based on the total weight of the dry materials a) to σ) .
Examples of thickeners are polysaccharides such as cellulose ethers and modified cellulose ethers, starch ethers, guar gum or xanthan gum, phyllosilicates, polycarboxylic acids such as polyacrylic acid and the partial esters thereof, polyvinyl alcohols, which optionally have been acetalized and/or hydropho- bically modified, casein, and associative thickeners. It is also possible to use mixtures of these or other thickeners. Preference is given to the cellulose ethers, modified cellulose ethers, optionally acetalized and/or hydrophobically modified, polyvinyl alcohols, and mixtures thereof. It is preferred to use from 0.05 to 2.5% by weight, with particular preference from 0.05 to 0.5% by weight, of thickeners, in each case based on the total weight of the dry materials a) to c) .
Frequently used retardants have been selected from hydroxycar- boxylic acids or dicarboxylic acids or salts thereof, as well as saccharides. Examples include oxalic acid, succinic acid, tartaric acid, gluconic acid, citric acid, sucrose, glucose, fructose, sorbitol and pentaerythritol . Further examples of retarders are polyphosphates, metaphosphoric acid, and borax.
If the polymer component b) is used in form of a redispersible polymer powder, the cementitious sealing compositions is generally prepared by mixing components a) to c) , and optionally one or more of the above mentioned further ingredients, to a dry mortar in conventional powder mixers and homogenizing the mixture. The amount of water needed for processing is added immediately prior to processing. Another possible procedure is to add individual components only subsequently to the mixture prepared by stirring with water. If the polymer component b) is used in form of an aqueous polymer dispersion, the components a) to c) , and optionally- further ingredients, and if necessary an additional amount of water are mixed for obtaining a pasty mortar.
The water ratio to be added to the dry mix depends on the type of application. Usually water is added in an amount of 25 % by weight to 50 % by weight, based on the dry weight of the ce- mentitious sealing composition.
The cementitious sealing composition is used as a coating for the protection of concrete materials, particulary as a salt resistant coating for concrete structures which are exposed to seawater, especially at waterline (splash zone area) .
Examples :
For testing the cementitious sealing compositions the following polymer components have been used:
Polymer 1:
Redispersible polymer powder on the basis of a vinyl aσetate- ethylene -copolymer with a glass transition temperature Tg of - 70C.
Polymer 2 :
Redispersible polymer powder on the basis of a vinyl acetate- ethylene-versatiσ acid ester-copolymer with a glass transition temperature Tg of -140C.
The sealing slurry compositions of table 1 have been prepared with the following method:
The constituents of the formulation were mixed dry for 3 minutes in a mortar mixer. The water was then added, and mixing was continued for a further 2 minutes. After a maturing time of 10 minutes, the mortar was mixed for 30 seconds and then spread by means of a trowel in a Teflon template to give a 2 mm thick sealing coat, after drying it was removed from the template and then stored at the following conditions:
28 days standard conditions (SC) 14 days SC + 14 days water immersion (WI) 14 days SC + 7 days WI + 7 days SC 7 days SC + 21 days sea salt water (300C) (SSW) 7 days SC + 21 days SSW + 2 days SC
After storage, tensile bars were stamped from the sealing coats and the tensile strength (N/mrn2) and elongation at break (%) of these were determined in a tensile test in accordance with DIN 53504 on an Instron tensile tester at an extension rate of 10 mm/min. Crack bridging (mm) was determined according EN 14891.
The mean values of the individual series of measurements are given in Table 1.
Table 1:
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