Foam concrete and its use

Abstract

Foam concrete comprising a cement paste mixture, including Portland cement and calcium aluminate (SCA cement), and the additives aluminum hydroxide for accelerating hardening, aluminum stearate as a hydrophobing additive, polyacrylic acid derivatives as a plasticizer, lithium carbonate as a reaction accelerator, and fillers as a dry mass, which is mixed with a foaming agent comprising a mixture of a rhamnolipid-alginate polymer complex and water, characterized in that the composition contains 50 to 90 wt.% dry mass of the cement paste mixture, the additives, and the fillers, and 10 to 50 wt.% of the liquid foaming agent foamed from the foaming agent and the aqueous solution, wherein the cement paste mixture contains 1 to 30 wt.% mineral and / or organic and / or inorganic substances as fillers, and the foaming agent mixture contains 0.5 to 2.0 wt.% an aqueous solution comprising a mixture of 30 to 85 wt.%.% demineralized water, 5 - 35 wt.% olefin sulfonates and 10 - 35 wt.% butyldiglycol, are added.

Description

[0001] The invention relates to a composition for a foam concrete, wherein the term “foam concrete” is understood to mean a hydrothermally cured, porous mineral material whose composition contains at least water, cement and foaming agent, and its use in construction.

[0002] Porous mineral materials of various types are known as building materials or construction compounds. Due to their high porosity, they have a significantly lower bulk density than concrete. Bulk density is the density of a porous body based on its volume, including the pore spaces.

[0003] While the bulk density of normal concrete is between about 2,000 and 2,600 kg / m 3 porous mineral building materials are usually used to achieve densities in the range of 80 to 600 kg / m 3The high air content results in improved thermal insulation properties. The decisive factor is the thermal conductivity, which is expressed as the thermal conductivity value lambda. The lower the value, the better the insulation.

[0004] Depending on the method of production, porous mineral materials are divided into aerated concrete and foam concrete. Aerated concrete is usually produced by mixing the raw materials quicklime, cement, quartz sand, and water with a pore-forming agent such as aluminum powder or aluminum paste. The metallic aluminum evolves hydrogen gas in the alkaline suspension, creating numerous small gas bubbles that foam the gradually stiffening mixture. After a steam curing process in an autoclave, the finished product consists of a crystalline phase of calcium silicate hydrate, which largely corresponds to the natural mineral tobermorite. In the production of foam concrete, foaming agents based on surfactants or proteins, for example, are used instead of aluminum. Typically, a pre-produced foam is mixed into the concrete, and the raw product is then steam-cured.Alternatively, direct foaming is also possible by blowing air into the building material mixture containing a foaming agent.

[0005] The subject matter of WO 2021 / 180309 A1 are processes for producing foam concrete in which air pores are introduced into aqueous concrete compositions by means of one or more air entraining agents and / or by introducing air, wherein the aqueous concrete compositions are based on one or more foam stabilizers, one or more protective colloid-stabilized polymers of ethylenically unsaturated monomers in the form of aqueous dispersions or water-redispersible powders, 30 to 95 wt.% cement, based on the dry weight of the components for producing the concrete compositions, optionally one or more fillers and optionally one or more additives.

[0006] DE 197 08 779 A1 describes a binder-bound foam and its production process, which contains an industrial waste material as a key component. The waste material is brick dust, which arises from the production of flat bricks and / or brick recycling. The production of the lightweight brick foam takes place in two process steps. First, the brick dust, the binder, the foaming agent, the additives, and, if required, a setting accelerator are mixed with water to form a suspension. This suspension is then foamed with compressed air.

[0007] WO 2018 / 060517 A1 describes a mixture containing rhamnolipids, alginates, and pyoverdine, as well as supramolecular rhamnolipid / alginate / pyoverdine complexes, as well as the use of the mixture according to the invention. In addition to a wide variety of applications, the use of the mixture or the supramolecular rhamnolipid / alginate / pyoverdine complex for foam concrete is also described.

[0008] EP 1 069 090 A1 relates to a hydrothermally cured, fiber-reinforced foam concrete product with micro-reinforcement, particularly in the form of cut slabs, essentially comprising a building material matrix consisting essentially of solid webs made of calcium silicate hydrate phases surrounding foam structure pores. The building material matrix comprises fibers for the micro-reinforcement, the fibers being elementalized flax fibers that have been ultrasonically broken down in a conventional manner. The invention also relates to a method for producing a fiber-reinforced foam concrete product.

[0009] It is known from DE 43 27 074 A1 to increase the structural strength of foam concrete to be used as a thermal insulation material, which is usually produced by mixing a slurry which essentially contains at least one burnt lime product and / or cement, quartz powder and water, and mixing in a separately prefabricated foam, followed by hydrothermal curing, by stirring glass fibres into the slurry.

[0010] WO 92 / 11217 A1 describes the usability of short fibers for so-called micro-reinforcement of fiber-reinforced aerated concrete under autoclave conditions. Most known fibers are unusable due to the autoclave conditions, are too expensive, or are harmful to health. Fibers made from the polymer polymethylpenthene, however, are said to be suitable because these fibers are inert in the autoclave process. Among other things, it is proposed to use the flexible fibers in lengths of 2 to 10 mm if the products are to be cut. The fibers are said to be easily dispersible and to provide a satisfactory bond between the fibers and the matrix material. The fibers are added in amounts of 0.5 to 5 wt.%. If necessary, the fibers are predispersed in water during the production of the aerated concrete.

[0011] DE 42 28 500 A1 relates to mineral foam structures which, by simply mixing a finely ground mixture of oxides of silicon, calcium, aluminum, and / or magnesium with water-soluble alkali silicates, the so-called water glasses, optionally with the addition of inert mineral fillers, and additives and blowing agents known per se, foam after introduction into molds or after application to substrates using suitable application devices and harden without external energy supply to form foam bodies with high strength.

[0012] DE 199 33 298 describes a hydrothermally hardened, fiber-reinforced foam concrete product with a density of less than 200 kg / m 3with a micro-reinforcement, comprising a building material matrix of solid webs of calcium silicate hydrate phases surrounding foam structure pores, wherein the building material matrix has fibers for the micro-reinforcement, wherein the fibers are elementarized flax fibers which are digested by means of ultrasound in a manner known per se, have a length of 0.1 to 5 mm and are contained in an amount of 0.1 to 2 wt.%.

[0013] The invention was therefore based on the object of providing a lightweight, porous insulating material with a low bulk density, whose thermal conductivity is even lower than that of the prior art, and which is characterized by high mechanical strength.

[0014] The invention is based on the object of providing an improved foam concrete whose composition contains at least water, cement and foaming agent and which is characterized by both a low thermal conductivity and a high mechanical strength with reduced cracking.

[0015] According to the invention, the object is achieved by a foam concrete with a composition of a cement paste mixture comprising Portland cement and calcium aluminate (SCA cement), and the additives aluminum hydroxide to accelerate hardening, aluminum stearate as an additive for hydrophobization, polyacrylic acid derivatives as a plasticizer, lithium carbonate as a reaction accelerator and fillers as a dry mass, which is mixed with a foaming agent comprising a mixture of a rhamnolipid-alginate polymer complex and water, wherein the composition contains 50 to 90 wt.% of a dry mass of the cement paste mixture, the additives and the fillers and 10 to 50 wt.% of the liquid foaming agent foamed from foaming agent and water, wherein 1 - 30 wt.% mineral and / or organic substances are added to the cement paste mixture as fillers and 0.5 to 2.0 wt.% of an aqueous solution comprising a mixture of 30 to 85 wt.% demineralized water, 5 - 35 wt.% olefin sulfonates and 10 - 35 wt.% butyldiglycol.

[0016] The foam concrete contains 50-90 wt.% of a cement paste mixture comprising 20-70 wt.% Portland cement, 8-50 wt.% SCA cement, and 0-70 wt.% CSA cement, as dry matter. Mineral substances in powder form and / or mineral dusts and / or organic substances in fiber form and / or powder or granulate form are added to the dry matter, either individually or as a mixture.

[0017] Ground clay or loam powder, ground brick powder, ground pumice powder, and / or ground powder from recycled mineral building materials can be added as mineral substances. Brick grinding dust and / or concrete block grinding dust can also be added as mineral dust.

[0018] Organic materials that can be added in fiber form include down feathers and / or shredded feathers and / or sheep's wool and / or cotton and / or wood fibers, and / or fluff from yarn or wool production and / or fibers from shredded textiles. Other organic materials that can be added include rubber granules and / or rubber powder from recycled tires, and / or inorganic materials that can be added include perlite granules and / or perlite powder. The fiber length is 2 to 30 mm, preferably 10 to 15 mm. The granules have a diameter of 0.5 to 3 mm, preferably 1 to 1.5 mm.

[0019] The cement paste mixture can be supplemented with 0.01 to 1.0 wt.% of a polyacrylic derivative, 0.01 to 0.5 wt.% of lithium carbonate to adjust the setting time, 0.1 to 1.0 wt.% of aluminum hydroxide to accelerate curing, and 0.5 to 3.0 wt.% of aluminum stearate to impart hydrophobicity, based on the dry mass. This hydrophobicity improves the foam's stability.

[0020] A foam is stirred into the dry mixture of cement paste, fillers, and additives. The foam is formed from a foaming agent and water with the addition of the aqueous solution in a ratio of 1:10 to 1:50, preferably 1:20. The foam has a foam density of 30 to 100 g / l, preferably 60 g / l. After curing, the foam concrete has a thermal conductivity of 30 to 42 mW / mK.

[0021] A rhamnolipid-alginate polymer complex and an aqueous solution of demineralized water with additives of olefin sulfonates and butyldiglycol are used as foaming agents. Additional additives to the mixture include sodium lauryl sulfoacetate (anionic foaming agent), decyl glycoside (nonionic foaming agent), polyoxyethylene(20) sorbitan monolaurate (nonionic foaming agent), alkyl polyglycosides (nonionic surfactants), and tetrasodium N,N-bis(carboxylatomethyl)-L-glutamate (complexing agent).

[0022] The foam concrete according to the invention comprises, as dry matter, a composition of 50 to 90 wt.% of a cement paste mixture comprising 20 to 70 wt.% Portland cement, 20 to 70 wt.% CSA cement, 18 to 22 wt.% SCA cement, 0.1 to 1.0 wt.% aluminum hydroxide, 0.5 to 3.0 wt.% aluminum stearate, 0.01 to 1.0 wt.% polyacrylic acid derivative, 0.01 to 0.5 wt.% lithium carbonate, 1 to 15 wt.% mineral substances in powder form and 1 to 15 wt.% organic substances in fiber form.

[0023] The foam concrete according to the invention is suitable as in-situ foam concrete for filling cavities, for producing wall, floor or ceiling elements in panel or block form, for producing insulation panels for thermal insulation composite systems or for filling hollow molded parts made of other materials, in particular building blocks with hollow chambers, and thus subsequently insulating or stiffening them.

[0024] The invention will be described in more detail using an embodiment.

[0025] The foam concrete comprises a cement paste with a first cement type, in particular a standard cement (Portland cement), a second cement type, in particular a CSA cement, and a third cement type, in particular an SCA cement. Depending on the application, certain aggregates and fillers can be added to the cement paste. The aggregates make up a total weight fraction of between 0.01 wt.% and 22 wt.% in the cement paste and / or the finished foam concrete, while the fillers typically make up a weight fraction of between 0.01 wt.% and 20 wt.%.

[0026] A rhamnolipid-alginate polymer complex, produced using microorganisms of the genus Pseudomonas, is used as a foaming agent. The rhamnolipid biosurfactants obtained by culturing bacteria of the genus Pseudomonas have excellent surfactant properties and are particularly useful in the production of building materials, especially foam concrete. The rhamnolipid-alginate polymer complex consists of alginate, mono-, and di-rhamnolipids.

[0027] For the production of foam concrete, a superhydrated foam agent, also known as foam water, is preferably used. The foaming agent and aqueous solution are preferably mixed in a ratio of 1:20 using local continuous or batch mixing technology. In a foam generator, a foam is created from water, foaming agent, and air via one or more foam pipes. The foam has a foam density of 60 g / l. This allows for highly stable foam concrete mixes with pleasingly low thermal conductivities.

[0028] Preferred embodiments of the foam concrete according to the invention are shown below.

[0029] Example 1 describes a foam concrete with a total dry mass of 80 wt.% and 20 wt.% of the foamed liquid foaming agent. The total dry mass comprises a cement paste mixture consisting of 45 wt.% Portland cement, 25 wt.% CSA cement, 20 wt.% SCA cement, 0.5 wt.% aluminum hydroxide, 1.5 wt.% aluminum stearate, 0.3 wt.% polyacrylic acid derivative, 0.2 wt.% lithium carbonate, 7.5 wt.% of a mixture of ground brick powder and brick grinding dust as mineral substances, and 2.5 wt.% feathers as organic substances. The total dry mass is mixed with 20 wt.% of a foamed liquid foaming agent comprising a mixture of rhamnolipid-alginate polymer complex, water with the addition of 1 wt.% of an aqueous solution comprising a mixture of 70 wt.% demineralized water, 10 wt.% olefin sulfonate and 20 wt.% butyldiglycol.The foamed liquid foam agent is formed from the foaming agent and water with the added aqueous solution in a ratio of 1 to 15 and has a foam density of 60 g / l.

[0030] Example 2 describes a foam concrete with a total dry mass of 80 wt.% and 20 wt.% of the foamed liquid foaming agent. The total dry mass comprises a cement paste mixture consisting of 45 wt.% Portland cement, 25 wt.% CSA cement, 20 wt.% SCA cement, 0.5 wt.% aluminum hydroxide, 1.5 wt.% aluminum stearate, 0.3 wt.% polyacrylic acid derivative, 0.2 wt.% lithium carbonate, 7.5 wt.% ground recycled mineral building materials, and 2.5 wt.% fibers from shredded used textiles with a length of 10 to 15 mm as organic matter. The total dry mass is mixed with 20 wt.% of a foamed liquid foaming agent comprising a mixture of rhamnolipid-alginate polymer complex, water with the addition of 1 wt.% of an aqueous solution comprising a mixture of 70 wt.% demineralized water, 10 wt.% olefin sulfonate and 20 wt.% butyldiglycol.The foamed liquid foam agent is formed from the foaming agent and water with the added aqueous solution in a ratio of 1 to 15 and has a foam density of 60 g / l.

[0031] Example 3 describes a foam concrete with a total dry mass of 80 wt.% and 20 wt.% of the foamed liquid foaming agent. The total dry mass comprises a cement paste mixture consisting of 45 wt.% Portland cement, 25 wt.% CSA cement, 20 wt.% SCA cement, 0.5 wt.% aluminum hydroxide, 1.5 wt.% aluminum stearate, 0.3 wt.% polyacrylic acid derivative, 0.2 wt.% lithium carbonate, 7.5 wt.% ground pumice powder as the mineral substance, and 2.5 wt.% fluff from yarn or wool production as the organic substance. The total dry mass is mixed with 20 wt.% of a foamed liquid foaming agent comprising a mixture of rhamnolipid-alginate polymer complex, water with the addition of 1 wt.% of an aqueous solution comprising a mixture of 70 wt.% demineralized water, 10 wt.% olefin sulfonate and 20 wt.% butyldiglycol.The foamed liquid foam agent is formed from the foaming agent and water with the added aqueous solution in a ratio of 1 to 15 and has a foam density of 60 g / l.

[0032] Example 4 describes a foam concrete with a total dry mass of 80 wt.% and 20 wt.% of the foamed liquid foaming agent. The total dry mass comprises a cement paste mixture consisting of 45 wt.% Portland cement, 25 wt.% CSA cement, 20 wt.% SCA cement, 0.5 wt.% aluminum hydroxide, 1.5 wt.% aluminum stearate, 0.3 wt.% polyacrylic acid derivative, 0.2 wt.% lithium carbonate, 4.0 wt.% of a ground clay powder as the mineral substance, and 3.5 wt.% of rubber granulate from recycled tires with a diameter of 1 to 1.5 mm as the organic substance. The total dry mass is mixed with 20 wt.% of a foamed liquid foaming agent comprising a mixture of rhamnolipid-alginate polymer complex, water with the addition of 1 wt.% of an aqueous solution comprising a mixture of 70 wt.% demineralized water, 10 wt.% olefin sulfonate and 20 wt.% butyldiglycol.The foamed liquid foam agent is formed from the foaming agent and water with the added aqueous solution in a ratio of 1 to 15 and has a foam density of 60 g / l.

[0033] Example 5 describes a foam concrete with a total dry mass of 80 wt.% and 20 wt.% of the foamed liquid foaming agent. The total dry mass comprises a cement paste mixture consisting of 45 wt.% Portland cement, 25 wt.% CSA cement, 20 wt.% SCA cement, 0.5 wt.% aluminum hydroxide, 1.5 wt.% aluminum stearate, 0.3 wt.% polyacrylic acid derivative, 0.2 wt.% lithium carbonate, 3.0 wt.% of ground brick powder as the mineral substance, and 4.5 wt.% of perlite granules with a diameter of 1 to 1.5 mm as the inorganic substance. The total dry mass is mixed with 20 wt.% of a foamed liquid foaming agent comprising a mixture of rhamnolipid-alginate polymer complex, water with the addition of 1 wt.% of an aqueous solution comprising a mixture of 70 wt.% demineralized water, 10 wt.% olefin sulfonate and 20 wt.% butyldiglycol.The foamed liquid foam agent is formed from the foaming agent and water with the added aqueous solution in a ratio of 1 to 15 and has a foam density of 60 g / l.

[0034] The resulting foam concrete is placed in a mold, creating a block that can be further processed into a building element. Further processing may include shaping by sawing or cutting into slabs or blocks and / or a drying process.

[0035] Alternatively, if the building element is to be designed as an insulation panel, the still liquid or slurry foam concrete can be poured into a flat mold to dry and harden. The mold could be a formwork, for example. Several insulation panels can also be carved out of one formwork in this way. Other shapes for other building elements are, of course, also readily feasible.

[0036] Shaped bodies of any geometry can be produced from the foam concrete according to the invention. This includes insulating panels for thermal and acoustic insulation, carrier panels for decorative coverings made of other materials, duct systems for ventilation ducts and electrical wiring, e.g., for preventive fire protection, lightweight partition wall structures, core panels for sandwich constructions and composite elements, shaped parts for roller shutter boxes, heat-insulating and lightweight lintels for windows and doors, and half-shells for pipe insulation, to name just a few of the possible applications of bodies made from the foam concrete according to this invention. If necessary, the shaped bodies can be reinforced with inserted reinforcements made of fiber fleece, fabric, metal, etc.

[0037] Since foam concrete adapts to any shape, it is also possible to fill existing hollow molded parts made of other materials, especially building blocks with hollow chambers, and thus subsequently insulate or stiffen them.

[0038] These examples represent the multitude of possible design variants of mineral foam concretes and molded bodies produced therefrom according to the claims of this invention. They are therefore only typical examples.

[0039] This innovative foam concrete opens up a wide range of new applications due to its significant advantages over other thermal insulation materials (cost-effective, non-combustible, environmentally friendly, etc.). Sustainable thermal insulation offers extensive application potential both in new buildings and in energy-efficient renovations of existing buildings.

[0040] A typical application is in exterior wall or roof construction. Foam concrete can also be used on interior walls. It is preferably formed and, for example, sawn and / or cut into slabs or blocks. In this case, it can be used particularly advantageously as an insulation board, especially with particularly low thermal conductivity properties. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2021 / 180309 A1

[0005] DE 197 08 779 A1

[0006] WO 2018 / 060 517 A1

[0007] EP 1 069 090 A1

[0008] DE 43 27 074 A1

[0009] WO 92 / 11217 A1

[0010] DE 42 28 500 A1

[0011] DE 199 33 298

[0012]

Claims

[1] Foam concrete with a composition of a cement paste mixture comprising Portland cement and calcium aluminate (SCA cement), and the additives aluminium hydroxide to accelerate hardening, aluminium stearate as an additive for hydrophobicity, polyacrylic acid derivatives as a plasticiser, lithium carbonate as a reaction accelerator and fillers as a dry mass, which is mixed with a foaming agent comprising a mixture of a rhamnolipid-alginate polymer complex and water, characterized bythat the composition contains 50 to 90 wt.% dry mass of the cement paste mixture, the additives and the fillers and 10 to 50 wt.% of the liquid foaming agent foamed from the foaming agent and the aqueous solution, wherein 1 - 30 wt.% mineral and / or organic and / or inorganic substances are added to the cement paste mixture as fillers and 0.5 to 2.0 wt.% of an aqueous solution comprising a mixture of 30 to 85 wt.% demineralized water, 5 - 35 wt.% olefin sulfonates and 10 - 35 wt.% butyldiglycol are added to the foaming agent mixture. [2] Foam concrete according to claim 1, characterized by that 50 - 90 wt.% of the cement paste mixture comprising 20 - 70 wt.% Portland cement, 8 - 50 wt.% SCA cement and 0 - 70 wt.% CSA cement is added to the foam concrete. [3] Foam concrete according to claim 1, characterized bythat the foaming agent is foamed with the aqueous solution in a ratio of 1 to 5 to 1 to 80 to form a liquid foam agent with a foam density of 50 to 100 g / l. [4] Foam concrete according to claim 1, characterized by that mineral substances in powder form and / or mineral dusts are added to the foam concrete as fillers. [5] Foam concrete according to claim 4, characterized by that a ground clay or loam powder and / or a ground brick powder and / or a ground pumice powder and / or a ground powder from a recycled mineral building material is added as the mineral substance. [6] Foam concrete according to claim 4, characterized by that brick grinding dust and / or concrete block grinding dust is added as mineral dust. [7] Foam concrete according to claim 1, characterized by that organic substances in fiber form, powder or granulate form are added to the foam concrete as fillers. [8] Foam concrete according to claim 7, characterized by that down feathers and / or shredded feathers and / or sheep's wool and / or cotton and / or wood fibres are added as organic substances in fibre form. [9] Foam concrete according to claim 7, characterized by that the organic substances added are fluff from yarn or wool production and / or fibers from shredded textiles. [10] Foam concrete according to claim 7, characterized by that rubber granulate and / or rubber powder from recycled tires are added as organic substances. [11] Foam concrete according to claim 1, characterized by that perlite granules and / or perlite powder are added as inorganic substances. [12] Foam concrete according to claim 1, characterized by that the foam concrete has a thermal conductivity of 28 to 44 mW / mK after hardening. [13] Foam concrete according to claim 1 and at least one of claims 2 to 12 characterized bythat the composition contains 50 to 90 wt.% as dry matter of a cement paste mixture comprising 20 to 70 wt.% Portland cement, 20 to 70 wt.% CSA cement, 18 to 22 wt.% SCA cement, 0.1 to 1.0 wt.% aluminum hydroxide, 0.5 to 3.0 wt.% aluminum stearate, 0.01 to 1.0 wt.% polyacrylic acid derivative, 0.01 to 0.5 wt.% lithium carbonate, 1 to 15 wt.% mineral substances in powder form and 1 to 15 wt.% organic substances in fiber form. [14] Foam concrete according to claim 1 and at least one of claims 2 to 12, characterized by that the composition contains 50 to 90 wt.% as dry matter of a cement paste mixture comprising 20 to 70 wt.% Portland cement, 20 to 70 wt.% CSA cement, 18 to 22 wt.% SCA cement, 0.1 to 1.0 wt.% aluminum hydroxide, 0.5 to 3.0 wt.% aluminum stearate, 0.01 to 1.0 wt.% polyacrylic acid derivative, 0.01 to 0.5 wt.% lithium carbonate, 1 to 15 wt.% mineral substances in powder form and 1 to 15 wt.% recycled materials in powder and / or fiber form. [15] Use of the foam concrete according to claim 1 and at least one of claims 2 to 14 as in-situ foam concrete for filling cavities. [16] Use of the foam concrete according to claim 1 and at least one of claims 2 to 14 for the production of wall, floor or ceiling elements in slab or block form. [17] Use of the foam concrete according to claim 1 and at least one of claims 2 to 14 for the production of insulation boards for thermal insulation composite systems. [18] Use of the foam concrete according to claim 1 and at least one of claims 2 to 14 for filling building blocks with hollow chambers.