Porous mineral building material and its use

Abstract

Porous mineral building material mass in the form of a foamed concrete, the composition of which comprises at least water, cement and a foaming agent, characterized in that the composition consists of a cement paste mixture as a dry mass, comprising Portland cement, calcium sulfoaluminate and calcium aluminate, additives for accelerating hardening and / or for adjusting the setting time and / or for hydrophobing and optionally fillers, which is mixed with a foaming agent comprising a mixture of a rhamnolipid alginate polymer complex, sodium lauryl sulfoacetate, decyl glycoside, polyoxyethylene(20) sorbitan monolaurate, alkyl polyglycosides, tetrasodium N,N-bis(carboxylatomethyl)-L-glutamate and water.

Description

[0001] The invention relates to a composition of porous mineral building materials in the form of a foam concrete, the term “foam concrete” being understood to mean a hydrothermally hardened, porous mineral material whose composition contains at least water, cement and foaming agent, as well as its use.

[0002] Porous mineral materials of various types are known as building materials or masses. 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 capacity.

[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] EP 3 599 228 B1 describes a process for producing a porous mineral building material based on calcium silicate hydrate, wherein the aqueous mixture comprises, based on the total solids content, 25-35 wt.% SiO2, 18-35 wt.% hydrated lime, 25-45 wt.% cement, 1-5 wt.% potassium silicate, optionally 5-10 wt.%, preferably 6-8 wt.% kaolin and 3-8 wt.% of a hardening accelerator, and the aqueous mixture is mixed with a foaming agent comprising a surfactant or protein.

[0006] DE 10 2010 062 762 B4 describes a process for producing foam concrete comprising the steps of a) forming a cement paste consisting of cement, water, a networking agent, which is a mixture of negatively charged inorganic substances and organic substances with amide groups with corresponding cations, which comprise divalent or trivalent cations or a mixture thereof and / or an organic compound with excess positive charges from the class of cationic surfactants and / or quaternary ammonium compounds, and optionally at least one additive, by mixing the components in a mixer;b) Formation of a foam consisting of water, air and a protein-based foaming agent made of non-polar and polar amino acids by means of a foam generator, wherein the foaming agent is a protein which consists of 50 to 80 mass% of the amino acids A (alanine), E (glutamic acid), G (glycine), I (isoleucine), L (leucine), M (methionine), P (proline), Q (glutamine) and V (valine), with a molecular weight between 20,000 and 120,000 Daltons and the remaining 20 to 50 mass% are other amino acids; c) Mixing the cement paste formed in step a) and the foam formed in step b) in a mixer and / or in a truck mixer; and d) Drying the foam concrete.

[0007] 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.

[0008] DE 10 2009 052 435 A1 relates to a mixture for foam concrete, in particular a raw material mixture for autoclave foam concrete, comprising cement, sand, a protein-containing foam-generating agent, and water. Sodium fluoride and fine ash and slag residues from solid fuel combustion are used as additives. This raw material mixture, Addiment Sb-31, contains the additional additive NaF as a protein-containing foam-generating agent, as well as fine ash and slag residues from solid fuel combustion with a specific surface area of ​​S sp of at least 300 m 2 / kg.

[0009] DE 10 2012 205 372 A1 describes a process and its composition in which two separate binder pastes, comprising cement, water, and at least one foaming agent, are produced separately. These pastes are then foamed into two separate cement foams of different compositions, which are then combined and homogenized into a single foam. The foaming agents used include a protein hydrolysate and Portland cement, calcium aluminate, or calcium aluminate with a sulfate component.

[0010] DE 10 2019 113 570 A1 describes a method for producing a foam concrete and a building element by combining a first mixture containing a first type of cement—regular cement—and a second mixture containing a second type of cement—rapid-setting cement. A CSA cement is preferably used as the rapid-setting cement.

[0011] DE 10 2012 205 372 A1 relates to the use of hydrolysates of glutamine-rich proteins for use as air-entraining agents in building materials, in particular as additives for building material mixtures that influence the air content of these building material mixtures. In addition to glutamine-rich peptides or peptide mixtures, the compositions can contain one or more additives selected from flow agents, binders, retarders, setting accelerators, anti-shrink additives, solvents, preservatives, pigments, antifreeze agents, polymers, additives for internal post-treatment, thickeners, hydrophobic agents, and / or flow agents. Preferred binders are selected from cement and binders containing calcium sulfate (or modifications thereof containing water of crystallization), such as gypsum. Preferred binders are cement or gypsum, particularly preferably cement. Any known cement can be used as the cement.Preferably, a cement containing at least one calcium silicate, aluminate, and / or ferrite is used. Portland cement (CEM I), Portland composite cement (CEM II), blast furnace cement (CEM III), pozzolanic cement (CEM IV), composite cement (CEM V), or high-alumina cement are preferred.

[0012] DE 10 2017 129 140 A1 relates to a method for producing a building element from foam concrete and a building element, in particular an insulating element. First, a cement paste comprising water, a special cement, and at least one additive from the group consisting of metakaolin, microsilica, nanosilica, hydroxyapatite, tricalcium phosphate, and / or fumed silica is produced in a high-speed colloid mixer. Second, a foam is produced from a foaming agent and air. Third, the cement paste and the foam are combined in a mixing station by mixing them together to form foam concrete.

[0013] DE 10 2015 013 396 A1 describes a process for producing a fast-setting mineral foam and its composition. Two separate binder pastes, comprising cement, water, and at least one foaming agent, are produced separately. These pastes are then foamed separately to form two separate cement foams of different compositions. These foams are then combined and homogenized into a single foam. The foaming agents used include a protein hydrolysate and Portland cement, calcium aluminate, or calcium aluminate with a sulfate component.

[0014] DE 10 2010 062 762 A1 describes a process for producing foam concrete with a dry density of less than 400 kg / m 3A cement paste and a protein foam are prepared separately and then mixed together. The protein foaming agent consists of nonpolar and polar amino acids.

[0015] 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.

[0016] 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.

[0017] The invention is based on the object of providing an improved porous mineral building material in the form of a foam concrete, the composition of which contains at least water, cement, and foaming agents, and which is characterized by both low thermal conductivity and high mechanical strength. The porous mineral building material, in the sense of the present application, is a material based on calcium silicate hydrate. More specifically, the invention relates to an improved foam concrete, whereby the term "foam concrete" is understood to mean a hydrothermally cured, porous mineral material, the production of which uses at least water, cement, and foaming agents, preferably based on surfactants or proteins.

[0018] According to the invention, the object is achieved by a porous mineral building material mass in the form of a foam concrete with the composition of a cement paste mixture as dry mass, comprising Portland cement, calcium sulfo-aluminate (CSA cement) and calcium aluminate (SCA cement), additives for accelerating the hardening and / or for adjusting the setting time and / or for hydrophobization and optionally consisting of fillers, and a foaming agent comprising a mixture of a rhamnolipid-alginate polymer complex, sodium lauryl sulfoacetate, decyl glycoside, polyoxyethylene(20) sorbitan monolaurate, alkyl polyglycosides, tetrasodium N,N-bis(carboxylatomethyl)-L-glutamate and water.

[0019] The cement linseed mixture contains Portland cement, calcium sulfo aluminate (CSA cement) and calcium aluminate (SCA cement) in a ratio of 1 to 0.4 to 0.1 to 1 to 1 to 0.8 based on the dry mass.

[0020] A foam is stirred into the cement paste mixture in dry form, the foam being formed from a foaming agent and water in a ratio of 1 to 10 to 1 to 50, preferably 1 to 15, and having a foam density of 30 to 100 g / l, preferably 60 g / l.

[0021] 0.01 to 1.0 wt.% of a polyacrylic derivative and up to 0.1 wt.% lithium carbonate are added to the cement paste mixture as a dry mass as additives to adjust the setting time. Furthermore, 18 to 22 wt.% calcium sulfate and 0.1 to 1.0 wt.% aluminum hydroxide can be added to the cement paste mixture as a dry mass as additives to accelerate curing.

[0022] As an additional additive, 0.5 to 3.0 wt.% aluminum stearate, based on the dry mass, can be added to the cement paste mixture to make it water-repellent. This water-repellent treatment improves the foam's stability.

[0023] The building material mass contains 50 to 85 wt.%, preferably 65 wt.%, dry mass of the cement paste mixture, the additives and optionally the fillers, whereby water can be added to the mixture if necessary, and 30 to 40 wt.%, preferably 35 wt.%, of the liquid foaming agent foamed from foaming agent and water.

[0024] The foaming agent used is a mixture of a rhamnolipid-alginate polymer complex, sodium lauryl sulfoacetate (anionic foaming agent), decyl glycoside (nonionic foaming agent), polyoxyethylene(20) sorbitan monolaurate (nonionic foaming agent), alkyl polyglycosides (nonionic surfactants), tetrasodium N,N-bis(carboxylatomethyl)-L-glutamate (complexing agent) and water, preferably demineralized water.

[0025] The porous mineral building material has a dry bulk density of 80 to 150 kg / m 3 , preferably 125 kg / m 3, and a compressive strength after curing of 80 to 140 kPa, preferably 115 kPa. The thermal conductivity is in the range of 0.03 to 0.05 W / mk, preferably 0.038 W / mk.

[0026] The building material mass contains a composition based on the dry mass of 20 to 70 wt.% Portland cement, preferably 25 to 35 wt.%, 20 to 70 wt.% CSA cement, preferably 25 to 35 wt.%, 3 to 30 wt.% SCA cement, preferably 18 to 22 wt.%, 10 to 40 wt.% anhydride, preferably 18 to 22 wt.%, 0.1 to 1.0 wt.% aluminum hydroxide, preferably 0.15 to 0.35 wt.%, 0.5 to 3.0 wt.% aluminum stearate, preferably 0.5 to 1.0 wt.%, 0.01 to 1.0 wt.% polyacrylic acid derivative, preferably 0.05 to 0.5 wt.% and up to 15 wt.% alumina and up to 0.1 Wt.% lithium carbonate.

[0027] The porous mineral building material 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 or for producing insulation panels for thermal insulation composite systems.

[0028] The invention will be described in more detail using an embodiment.

[0029] The porous mineral building material composition according to the invention comprises a cement paste for producing foam concrete, wherein this cement paste comprises at least the following components: water, a cement mixture comprising a first type of cement, in particular a standard cement (Portland cement), a second type of cement, in particular a CSA cement, and a third type of cement, in particular an SCA cement. Additives to accelerate hardening, in particular calcium sulfate (anhydride) and / or aluminum hydroxide, can be added to the cement paste. Furthermore, additives such as polyacrylic acid derivatives as plasticizers and / or lithium carbonate as a reaction accelerator for adjusting the setting time, and aluminum stearate for hydrophobicization, as well as fillers such as alumina and / or calcium silicate, can be added.

[0030] Depending on the application, specific aggregates and fillers are used. The aggregates make up a total weight percentage 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 percentage of between 0.01 wt.% and 20 wt.%.

[0031] In a preferred embodiment, the mineral building material composition according to the invention is further explained using the following example. A cement paste is used, which, depending on the machine technology and ambient conditions, consists of the following components: 18.7 kg of Portland cement, 18.7 kg of calcium sulfo-aluminate cement (CSA cement), and 11.9 kg of amorphous calcium aluminate (SCA cement). 11.9 kg of anhydride (alumina), 0.15 kg of polyacrylic acid derivative, 0.5 kg of aluminum stearate, 0.18 kg of aluminum hydroxide, and 0.02 kg of lithium carbonate are added. The total dry mass of the cement paste is approximately 62.1 kg, to which rhamnolipids, in particular, are subsequently added as a foaming agent. In this way, very stable foam concrete mixtures can be achieved with pleasingly low thermal conductivities. In this way, thermal conductivities of the components of between 0.03 and 0.05 W / mK, preferably between 0.03 and 0.04 W / mK, can be achieved.

[0032] 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.

[0033] The foaming agent comprises a mixture of 1.0 wt% secondary sodium alkyl sulfonates, 1.0 wt% sodium lauryl sulfoacetate, 2.0 wt% rhamnolipid alginate polymer complex, 1.5 wt% decyl glycoside, 0.5 wt% polyoxyethylene(20) sorbitan monolaurate, 3.0 wt% alkyl polyglycosides, 0.5 wt% tetrasodium N,N-bis(carboxylatomethyl)-L-glutamate and the balance demineralized water.

[0034] For the production of foam concrete, a superhydrated foam agent, also known as foam water, is preferably used. The foaming agent and water are mixed in a ratio of 1:15 using local continuous or batch mixing technology. In a foam generator, a foam is created from water, foaming agent, and air via a foam pipe. The foam has a foam density of 75 g / l.

[0035] Approximately 37.9 kg of foam water is mixed into the total dry mass of approximately 62.1 kg, resulting in a raw foam concrete mix. According to this example, approximately 100 kg of fresh foam concrete is produced with a bulk density of 125 kg / m 3 .

[0036] The resulting raw mixture is placed in a mold, producing a block with a volume of approximately 0.8 m 3is created and further processed into a building element. Further processing may include shaping by sawing or cutting into panels or blocks and / or a drying process.

[0037] Alternatively, if the building element is to be designed as an insulation panel, the foam concrete, which may still be liquid or slurry, 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.

[0038] The inventive composition of the porous mineral building material as foam concrete surprisingly makes it possible, on the one hand, to significantly reduce thermal conductivity and achieve a thermal conductivity of less than 0.05 W / mK. On the other hand, it succeeds in ensuring high mechanical strength of the material. The porous mineral building material produced according to the invention is preferably characterized by significantly improved compressive strength and flexural tensile strength compared to hydrothermally cured foam concrete obtained by other methods from the same components. The compressive strength is 115 kPa and the thermal conductivity is 0.039 W / mK. The inventive composition of the porous mineral building material is therefore particularly suitable as an insulating material for thermal insulation and as a fire protection material.

[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.). This sustainable thermal insulation offers extensive potential for use in both new buildings and energy-efficient renovations.

[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.

Claims

[1] Porous mineral building material in the form of a foam concrete, the composition of which includes at least water, cement and foaming agent, characterized by that the composition consists of a cement paste mixture as a dry mass, comprising Portland cement, calcium sulfo-aluminate and calcium aluminate, additives for accelerating the hardening and / or for adjusting the setting time and / or for hydrophobization and optionally of fillers, which is mixed with a foaming agent comprising a mixture of a rhamnolipid-alginate polymer complex, sodium lauryl sulfoacetate, decyl glycoside, polyoxyethylene(20) sorbitan monolaurate, alkyl polyglycosides, tetrasodium N,N-bis(carboxylatomethyl)-L-glutamate and water. [2] Porous mineral building material according to claim 1, characterized bythat the foaming agent is foamed with water in a ratio of 1 to 10 to 1 to 50 to form a liquid foam agent with a foam density of 50 to 100 g / l. [3] Porous mineral building material according to claim 1, characterized by that 18 to 22 wt.% calcium sulfate and 0.1 to 1.0 wt.% aluminum hydroxide, based on the dry mass, are added as additives to accelerate curing. [4] Porous mineral building material according to claim 1, characterized by that 0.01 to 1.0 wt.% of a polyacrylic derivative and up to 0.1 wt.% of lithium carbonate, based on the dry mass, are added as additives to adjust the setting time. [5] Porous mineral building material according to claim 1, characterized by that up to 15 wt.% clay and / or up to 5 wt.% calcium silicate, based on the dry mass, are added as filler. [6] Porous mineral building material according to claim 1, characterized bythat the building material mass contains 50 to 85 wt.% dry mass from the cement paste mixture, the additives and, if applicable, the fillers and 15 to 50 wt.% of the liquid foaming agent foamed from foaming agent and water. [7] Porous mineral building material according to claim 1, characterized by that the building material mass has a dry bulk density of 80 to 150 kg / m 3 has. [8] Porous mineral building material according to claim 1, characterized by that the building material mass has a compressive strength of 80 to 140 kPa after curing. [9] Porous mineral building material according to claim 1, characterized by that the building material mass has a thermal conductivity of 0.03 to 0.05 W / mk after curing. [10] Use of the porous mineral building material according to claim 1 and at least one of claims 2 to 9 as in-situ foam concrete for filling cavities. [11] Use of the porous mineral building material according to claim 1 and at least one of claims 2 to 9 for the production of wall, floor or ceiling elements in plate or block form. [12] Use of the porous mineral building material according to claim 1 and at least one of claims 2 to 9 for the production of insulation boards for thermal insulation composite systems.