Process for producing hydrothermally hardened aerated or foamed concrete moldings and aerated or foamed concrete moldings produced according to the process

Abstract

The present invention relates to a process for producing hydrothermally hardened aerated or foamed concrete moldings and to aerated or foamed concrete moldings produced according to the process.

Description

[0001] Process for the production of hydrothermally cured aerated or foamed concrete moldings and aerated or foamed concrete moldings produced by the process

[0002] The present invention relates to a process for producing hydrothermally cured aerated or foamed concrete moldings, in particular in the form of aerated or foamed concrete blocks. Particularly preferred are aerated concrete blocks of standardized grades regarding strength and bulk density according to DIN EN 771-4:2015-11 in combination with DIN 20000-404:2018-04 with bulk densities of 305 to 1000 kg / m³. 3 However, non-standardized bricks can also be produced, e.g. with a density between 200 and < 305 kg / m 3 and aerated or foam concrete insulation material, preferably aerated or foam concrete insulation boards, with a bulk density between e.g. 70 and < 200 kg / m 3 , preferably 70 to 150 kg / m 3Furthermore, reinforced aerated or foam concrete precast elements with bulk densities such as standardized or non-standardized aerated or foam concrete blocks can also be manufactured.

[0003] Furthermore, the invention relates to such a porous or foam concrete molded body produced by means of the method.

[0004] Aerated concrete moldings consist of hydrothermally cured, porous calcium silicate hydrate material. They are produced from an aqueous mixture or fresh concrete mass containing at least one CaO component reactive in the hydrothermal process and at least one SiO2 component reactive in the hydrothermal process, a blowing agent, in particular aluminum powder and / or paste, and optionally, particularly inert, additives. Furthermore, the fresh concrete mass often contains at least one admixture, e.g., a plasticizer and / or a dispersant. The pourable or ready-to-cast fresh concrete mass is poured into a mold, allowed to expand and stiffen, cut, and then subjected to steam curing. In contrast to conventional, non-autoclaved concrete, aerated concrete material does not contain coarse aggregates with a grain size > 2.0 mm.

[0005] To produce hydrothermally cured foam concrete moldings, pre-formed foam is mixed into the fresh concrete mass instead of the foaming agent, or the fresh concrete mass containing a foaming agent is directly foamed by stirring, and then the pourable or ready-to-cast fresh concrete mass is poured into the mold. In both cases, the foaming process is omitted.

[0006] Conventional porous and foam concrete moldings therefore essentially consist of a solid web structure, which generally consists primarily of calcium silicate hydrate phases (CSH phases). "Primarily" means that the solid web structure consists of more than 50 mass% of the CSH phases, based on its dry mass. At high densities, e.g., > 650 kg / m 3, the content can also be below 50 mass%. The solid web framework can also contain, for example, residual quartz grains and possibly the inert additives. The residual quartz grains and the inert additives are embedded in the CSH phases. The solid web framework has webs that surround the pores (= macropores) artificially created by porosification or the addition of foam or foaming. In addition, the solid web framework has nano-, gel- and micropores that are embedded in or distributed within the CSH phases. The nano-, gel- and micropores are part of the solid web framework. The CSH phases of the solid web framework thus function as a binding phase in the solid web framework. They are largely cryptocrystalline to crystalline, usually CSH(I) and mainly 11 Å tobermorite.

[0007] Aerated or foam concrete blocks are building blocks made of aerated or foam concrete material. These generally unreinforced aerated or foam concrete blocks are primarily used as masonry units. Depending on the manufacturing tolerances, they are also referred to as aerated or foam concrete blocks or blocks. Reinforced aerated or foam concrete preforms are primarily used as large-format aerated or foam concrete components.

[0008] As already explained, porous or foam concrete moldings with very low bulk density are used as porous or foam concrete insulation bodies, preferably in the form of porous or foam concrete insulation boards.

[0009] Currently, aerated concrete blocks of standardized grades (EN 771-4 2015-1 1 and DIN 20000-404:2018-04) with bulk densities < 800 kg / m 3usually manufactured using so-called lime-cement formulations. Lime-cement formulations contain cement, usually Portland cement (CEM I), as both a CaO and SiO2 component. However, lime-cement formulations can also contain other standardized (e.g., CEM II or CEM III) or non-standardized cements. In addition to the cement, quicklime and / or hydrated lime are also included as a CaO component. In addition to the cement, lime-cement formulations also contain another SiO2 component, e.g., ground quartz, preferably ground sand, or fly ash. Furthermore, lime-cement formulations usually contain a sulfate carrier in the form of anhydrite and / or gypsum. The sulfate carrier in the cement acts as a setting regulator and is already contained in the cement. For standardized cements, the SO2 content is specified in DIN EN 197-1:2011-11. However, an additional sulfate carrier is usually added to the aerated concrete mixture.

[0010] Furthermore, pure lime formulations for the production of aerated concrete moldings are also known in the field. These lime formulations contain only quicklime and / or hydrated lime as the CaO component, but no cement or cement clinker. Consequently, they do not contain a sulfate carrier as a setting regulator. Generic lime formulations are known, for example, from WO 2009 / 121635 A1.

[0011] In addition, both lime-cement and lime formulations often contain aerated concrete aggregate. The aerated concrete aggregate is also known in the industry as aerated concrete flour or aerated concrete chippings. The aerated concrete aggregate typically comes from ongoing production. This means that scrap material and / or material from overproduction is crushed, usually using a roller crusher, screened, and used to manufacture new aerated concrete moldings. The aerated concrete aggregate is typically screened to achieve a consistent grain distribution with a maximum grain size of < 1200 μm.

[0012] Furthermore, for environmental reasons, efforts are being made to use aerated concrete material from demolition and dismantling projects for the production of aerated concrete moldings.

[0013] (https: / / www.bauhandwerk.de / news / ytong-startschuss-fuer-porenbeton-recycling-im-werk-wedel_3197859.html). The aerated concrete material must be recycled separately and is also crushed and sieved to a grain size of 0-1 mm. The reuse of recycled aerated concrete material contributes significantly to improving the carbon footprint.

[0014] Furthermore, other processes for the (re)use of aerated concrete aggregates are known:

[0015] DE 10 2006 049 836 A1 discloses the production of a hydraulic binder from construction waste, e.g., for the production of hydrothermally produced building materials, such as aerated concrete or sand-lime brick. The construction waste contains calcium silicate hydrates or cement stone as the binding phase and aggregates. According to the process of DE 10 2006 049 836 A1, fillers are first separated, and the remaining material is thermally treated to form a hydraulically active phase. For this purpose, the construction waste is crushed to a grain size of < 10 mm, the binding phase of the construction waste is enriched by sieving and / or sifting, and then heated to 600 to 800 °C for a period of 0.25 to 10 hours. According to DE 10 2006 049 836 A1, the construction waste can also be aerated concrete rubble.The binder-rich fine fraction is also obtained by sieving and / or classifying a grain fraction < 0.063 mm from the construction waste crushed to grain sizes < 10 mm.

[0016] In addition, the binder can be used to produce hydrothermally produced building materials, e.g. aerated concrete or sand-lime brick.

[0017] CN 113213846 A discloses a cement mortar containing crushed, calcined, and ground aerated concrete powder. Crushing initially produces aerated concrete granulate with a grain size of < 0.16 mm. Subsequent calcination and grinding activate the aerated concrete powder, making it a suitable replacement for cement.

[0018] CN 111439964 A discloses a dry mortar mixture containing aerated concrete waste, which has been ground into a powder with a grain size of < 45 pm. The aerated concrete waste is thermally treated at 700 to 900°C.

[0019] DE 20 2018 105 762 U1 discloses a concrete mixture in which the hydraulic binder is replaced by aerated concrete waste, which has a sieve residue of < 50% at a 45 pm sieve.

[0020] Aerated and foam concrete blocks exhibit good physical properties as building materials. In particular, aerated and foam concrete blocks exhibit high compressive strengths with a relatively low bulk density and low thermal conductivity. The so-called A-number is derived from a calculated relationship between the compressive strength and the dry bulk density. This represents the relative compressive strength of the aerated or foam concrete block. The higher the A-number, the better the compressive strength level. The A-number is calculated as follows:

[0021] A-number [ - ] = Compressive strength [N / mm 2 ] / ((Dry density [kg / dm 3 ]) 2 ■ 0.016 [Ndm 6 / mm 2 kg 2 ])

[0022] The goal in the production of aerated concrete moldings is always to achieve the lowest possible thermal conductivity while maintaining the best possible strength properties. To reduce thermal conductivity, it is known, for example, to use limestone flour as an additive in the production of aerated or foam concrete. Limestone flour is chemically inert and autoclave-resistant. The specific surface area of ​​the commonly used limestone flour is 4000–6000 cm2. 2 / g according to Blaine. The addition of limestone powder also reduces shrinkage and sorption moisture because it is incorporated into the solid web structure, thus reducing the CSH phases. This simultaneously reduces the compressive strength (A-number).

[0023] DE 10 2013 011 742 A1 also discloses the addition of PCC instead of natural, ground limestone powder. This slightly reduces thermal conductivity while maintaining strength.

[0024] DE 20 2008 017 703 U1 also addresses the reduction of thermal conductivity. According to DE 20 2008 017 703 U1, this is achieved by the solid web framework containing up to 10 mass % residual quartz grains and / or rock grains. This results in particular from the use of quartz powder with a Blaine specific surface area of ​​at least 6000 cm2. 2 / g and a corresponding autoclaving time.

[0025] The object of the present invention is to provide a method for producing a porous or foam concrete material with good strength properties.

[0026] Furthermore, a porous or foam concrete molded body produced by the process having good strength properties is to be provided.

[0027] These objects are achieved by a method having the features of claim 1 and a porous or foam concrete molded body having the features of claim 27. Advantageous developments of the invention are characterized in the respective subclaims. The invention is explained in more detail below with reference to a drawing. They show:

[0028] Figure 1 : The mineralogical composition of a ground suspension after different grinding times

[0029] Figure 2: The mineralogical composition of the ground suspensions used in the exemplary embodiments and the raw mixture of one of the suspensions

[0030] Within the scope of the invention, it was surprisingly found that the strength level (A-number) of a porous or foam concrete molded body can be improved compared to the use of a conventional porous or foam concrete grain if the porous or foam concrete grain is wet-ground together with at least a portion of the quicklime and / or hydrated lime used for production and at least a portion of the water used for production and only then is it mixed with the remaining components of the porous or foam concrete fresh mass.

[0031] According to the invention, at least a portion of the porous and / or foamed concrete grain used is mixed with at least a portion of the quicklime used and / or with at least a portion of the hydrated lime used and with at least a portion of the water used to form a suspension before mixing with the other components of the fresh concrete mass, the suspension is ground and the ground suspension is mixed with the other components of the fresh concrete mass.

[0032] In wet grinding, the material to be ground is mixed with a liquid, and a suspension or slurry is ground in the mill. In dry grinding, however, a bulk material or loose mixture of solids is ground. A suspension is generally a mixture in which the solid contained in the suspension is dispersed throughout the liquid, and the individual solid particles are completely wetted by the liquid.

[0033] A suspension is also flowable. A mixture is considered flowable if it has a consistency at which a slump can be determined according to DIN EN 1015-3: 2007-05.

[0034] Within the scope of the invention, it was surprisingly discovered that the strength of a porous or foam concrete molded body can be improved if the conventionally used porous or foam concrete grain is wet-ground together with quicklime and / or hydrated lime and water. During the wet grinding according to the invention, the porous or foam concrete grain and, if appropriate, also the quicklime and / or hydrated lime are comminuted to a grain size of < 100 pm, determined by laser light diffraction according to ISO 13320:2020-01. For the measurement, the suspension was dried to constant weight at 40°C and then mechanically deagglomerated.

[0035] This can compensate for or at least reduce the loss of strength that normally occurs when using aerated or foam concrete aggregates.

[0036] The cause of this effect has not yet been conclusively clarified. It is assumed to be a mechanochemical activation process of the mineral surfaces. Mineral transformations may also occur during grinding.

[0037] Within the scope of the invention, some of the suspensions were mineralogically examined using X-ray diffraction after wet grinding. It was found that, as expected, the quicklime reacted with the water to form hydrated lime (portlandite), and that carbonation occurred during the further course of wet grinding. Apparently, the hydrated lime and possibly also some of the amorphous CSH phases contained in the porous or foamed concrete aggregate reacted to form calcium carbonate (calcite and / or vaterite).

[0038] It is also possible that the amorphous CSH phases undergo structural changes and become more reactive, thus acting as nucleating agents. The amorphous CSH phases may react with the CaO from the quicklime and / or hydrated lime, increasing the C / S ratio of the CSH phases. It is also possible that the CaO from the quicklime and / or hydrated lime reacts with some of the residual quartz contained in the aerated or foamed concrete aggregate and, upon application of energy (grinding), forms new CSH nuclei. Consequently, the residual quartz from the aerated or foamed concrete aggregate is exposed during grinding and reduced in size, making it more reactive.

[0039] Considering the formation of calcium carbonate during wet grinding, the improvement in the A-number observed in the invention was surprising. It is known that the addition of limestone flour improves thermal conductivity but worsens the A-number.

[0040] The production of the porous or foam concrete molding according to the invention takes place in a manner known per se from a fresh concrete mass which has quicklime and / or hydrated lime as the hydrothermally reacting CaO component, at least one hydrothermally reacting SiO2 component, optionally at least one setting regulator, water and at least one blowing agent or prefabricated foam or a foaming agent.

[0041] According to the invention, the ground or activated suspension is also used to produce the fresh concrete mix. For this purpose, the ground suspension is mixed with the remaining water and, if used, the residual sludge, and then the solids are added. As is common in the production of aerated or foamed concrete, all components used for the fresh concrete mix preferably have a grain size of < 2 mm, determined according to DIN EN 1015-1:2007-05.

[0042] In the context of the invention, moreover, all components used for the fresh concrete mass preferably have a grain size of < 1 mm, preferably < 500 pm, particularly preferably < 150 pm, determined according to DIN EN 1015-1:2007-05 or, in the case of the suspension and the return sludge, determined as stated above by means of laser light diffraction.

[0043] The fresh concrete mass preferably contains Portland cement clinker flour. Portland cement clinker flour provides CaO and SiO2 for the reaction in the autoclave. It is therefore both a CaO and SiO2 component.

[0044] In addition, the at least one setting regulator is preferably a sulfate carrier, preferably anhydrite and / or hemihydrate and / or gypsum.

[0045] For the purposes of the invention, a sulfate carrier is understood to mean a raw material consisting of alkali metal sulfate or alkaline earth metal sulfate, preferably calcium sulfate. Of course, these raw materials may contain minor components or impurities. Minor components are undesirable and should therefore be interpreted as impurities.

[0046] In contrast, raw materials which contain sulfate minerals or sulfate compounds only as minor components are not referred to as sulfate carriers in the context of the invention.

[0047] Portland cement (CEM I) according to DIN EN 197-1:2011-11 is preferably used for the production of the fresh concrete mass. Portland cement is known to contain Portland cement clinker and at least one sulfate carrier, in particular anhydrite and / or hemihydrate and / or gypsum. Ground quartz, preferably ground quartz sand, and / or amorphous silica, preferably microsilica, are also preferably used as (further) SiO2 components for the production of the fresh concrete mass.

[0048] The quartz, preferably the quartz sand, preferably makes up the predominant proportion (i.e. > 50 mass%) of the SiO2 in the fresh concrete mass.

[0049] The fresh concrete mass may also contain other inert additives known in the art, preferably natural ground limestone flour and / or precipitated calcium carbonate (PCC).

[0050] The fresh concrete mass may also contain at least one additive known in the art, preferably a superplasticizer and / or a dispersant and / or a sedimentation inhibitor. The superplasticizer is preferably polycarboxylate ether (PCE). The dispersant is preferably polyacrylate (PAR) or an acrylic polymer or copolymer. The sedimentation inhibitor is preferably modified starch.

[0051] As already explained, the aerated and / or foamed concrete grains and the quicklime and / or hydrated lime are activated according to the invention by wet grinding. For this purpose, the aqueous suspension is first prepared from at least a portion of the aerated and / or foamed concrete grains used for production, at least a portion of the quicklime and / or hydrated lime used for production, and at least a portion of the mixing water used for production, and this suspension is wet-ground. As already explained, grinding is continued at least until the aerated and / or foamed concrete grains and the quicklime and / or hydrated lime have a grain size of < 100 pm.

[0052] At least the aerated or foamed concrete grains are therefore crushed during wet grinding. The ground suspension preferably also has a dgo value of 20 to 55 pm, preferably 25 to 40 pm, and / or a d50 value of 2 to 10 pm, preferably 3 to 6 pm, determined by laser light diffraction according to ISO 13320:2020-01 on the dried suspension as described above.

[0053] The at least one aerated or foamed concrete grain used for producing the suspension also preferably has a dgo value < 10 mm, preferably < 5 mm, particularly preferably < 2 mm, determined by means of the sieve passage according to DIN EN 1015-1:2007-05.

[0054] Unless otherwise stated, grain sizes are determined within the scope of the invention by means of sieve passage according to DIN EN 1015-1:2007-05.

[0055] The porous or foam concrete grain preferably has a maximum grain size of < 12 mm, preferably < 6 mm, particularly preferably < 3 mm.

[0056] Furthermore, the aerated or foamed concrete aggregate is preferably coarse-grained, meaning it also contains grains with a grain size > 125 pm, preferably also grains with a grain size > 250 pm. The aerated or foamed concrete aggregate therefore contains a coarse grain content.

[0057] In addition, the aerated or foamed concrete aggregate preferably has a bulk density of 400 to 700 g / l, preferably 450 to 600 g / l, according to DIN EN 1097-3:1998-06.

[0058] The aerated or foam concrete grain used to produce the suspension is preferably a by-product from aerated or foam concrete production, which has preferably been mechanically crushed by means of a crusher into the aerated or foam concrete grain with the specified grain size. The by-product is, in particular, technological rubble. Alternatively, the aerated or foam concrete grain is recycled material, which has also preferably been mechanically crushed by means of a crusher into the aerated or foam concrete grain with the specified grain size. The recycled material can also be recarbonated. In addition, it is known to contain adhering plaster and mortar residues. The advantage of the grinding according to the invention is that homogenization takes place and the adhering plaster and mortar residues are finely distributed.

[0059] Of course, the aerated or foam concrete aggregates can also be produced by mechanical crushing of specially manufactured aerated or foam concrete moldings.

[0060] In addition, it can also be aerated concrete material which was produced according to the process according to EP 3 789 362 A1 or according to WO 2009 / 121635 A1.

[0061] Furthermore, the aerated or foamed concrete aggregate is preferably not dried before grinding, nor is any other heat treatment at elevated temperatures carried out.

[0062] The suspension preferably has a W / F ratio (water / solids ratio) of 0.3 to 3.0, preferably 0.5 to 3.0, particularly preferably 1.0 to 2.5, most preferably 1.6 to 2.2. The W / F ratio is determined in a conventional manner from the dry mass of all solids used to prepare the suspension, the moisture content of the solids used, and the water used.

[0063] According to the invention, the upper and lower limits of the individual ranges for the W / F value can all be combined with one another.

[0064] Unless otherwise stated, the moisture content in this application is determined in accordance with DIN EN ISO 17892-1: 2022-08. On the one hand, the water / water ratio should be sufficiently high to ensure sufficient water is available for the reactions taking place and the suspension is sufficiently fluid for grinding and does not clump. The upper limit of the water / water ratio is limited, among other things, by the fact that additional irrigation water must be available for mixing the other components of the fresh concrete mass and ensure good grinding.

[0065] If necessary, the viscosity of the suspension can also be adjusted by adding a flow agent and / or liquefier.

[0066] Furthermore, the proportion of porous and / or foam concrete grains in the suspension is preferably 50 to 90 mass%, preferably 70 to 80 mass%, based on the dry mass of all solids used to produce the suspension.

[0067] Preferably, the suspension also contains the entire proportion of porous and / or foam concrete grains used to produce the porous or foam concrete molded body.

[0068] In addition, the suspension preferably does not contain the entire proportion of quicklime and / or hydrated lime used to produce the aerated or foam concrete molding. This means that a portion of the quicklime and / or hydrated lime used to produce the aerated or foam concrete molding is used directly to produce the fresh concrete mass. This has the advantage that the proportion of quicklime and / or hydrated lime can be varied depending on the recipe, while the amount added via the suspension remains in a constant ratio to the proportion of aerated and / or foam concrete aggregate.

[0069] The wet grinding is also carried out in a mill, preferably a drum mill, preferably in the form of a ball mill and / or rod mill, and / or a roller mill. The grinding time is preferably 45 minutes to 180 minutes, preferably 60 minutes to 120 minutes.

[0070] Within the scope of the invention, it was also discovered that a certain proportion of aerated or foamed concrete aggregate added via the ground suspension is advantageous. The fresh concrete mass preferably contains 10 to 35 mass%, preferably 10 to 30 mass%, particularly preferably 10 to 25 mass%, and most particularly preferably 15 to 25 mass%, of aerated or foamed concrete aggregate added via the suspension, based on the solids content (=total solids) in the fresh concrete mass.

[0071] The solids content is defined as the sum of all dry matter or solids, i.e., the dry mass of the freshly added dry matter or solids, as well as the dry matter or solids contained in the returned sludge and the dry matter or solids used to produce the suspension. The solids contained in additives, such as flow agents or dispersants, and in the blowing agent or foaming agent, are not included in the total solids; their content is related to the solids content.

[0072] In particular, the minimum proportion of aerated or foamed concrete aggregate added via the suspension should be 10 mass% in order to achieve a significant technical effect and be economically interesting.

[0073] As already explained, Portland cement clinker flour is preferably used as CaO and SiO2 component in the production of the fresh concrete mass.

[0074] The fresh concrete mass preferably has a Portland cement clinker powder content of 5 to 45 mass%, preferably 10 to 40 mass%, particularly preferably 15 to 35 mass%, based on the total solids content of the fresh concrete mass. The fresh concrete mass may also contain return sludge. The dry matter contained in the return sludge is the hydrate phase formed from the binder components and, if appropriate, inert substances such as porous or foamed concrete powder or rock powder. The hydrate phases have already reacted to such an extent that they no longer contribute to the green strength. They only react further during hydrothermal curing in the autoclave.

[0075] The fresh concrete mass preferably contains 2 to 30 mass%, preferably 2 to 20 mass%, particularly preferably 5 to 15 mass%, of return sludge (dry mass) based on the solids content in the fresh concrete mass.

[0076] The return sludge stabilizes the fresh concrete mass and the green porous or foam concrete molding.

[0077] The fresh concrete mass preferably contains 25 to 70 mass%, more preferably 35 to 60 mass%, of ground quartz, based on the solids content of the fresh concrete mass. This ensures, in particular, the formation of a sufficient amount of CSH phases.

[0078] Fly ash as a SiO2 component is preferably not included because it has a different solubility than quartz and the CSH phase formation is generally poorer.

[0079] The fresh concrete mass preferably also contains 5 to 40 mass%, preferably 5 to 30 mass%, particularly preferably 10 to 25 mass%, of quicklime and / or hydrated lime, based on the solids content of the fresh concrete mass. This ensures, in particular, the formation of a sufficient amount of CSH phases.

[0080] The W / F value (water / solids value) of the fresh concrete mass is also preferably 0.5 to 1.2, more preferably 0.5 to 1.1, more preferably 0.6 to 0.9, most preferably 0.6 to 0.8. The W / F value of the fresh concrete mass is calculated in a manner known per se from the dry mass of all solids used to produce the fresh concrete mass, the moisture content of the solids used, and the water used. This means, for example, that the water used to produce the suspension and the moisture content of the solids are also included in the total water content of the fresh concrete mass. And the dry mass of the solids used to produce the suspension is included in the total solids content of the fresh concrete mass.

[0081] Optionally, the fresh concrete mass also contains 0 to 20 mass%, preferably 0 to 17 mass%, particularly preferably 0 to 10 mass%, of inert additives, in particular rock flour, based on the solids content of the fresh concrete mass. The rock flour is preferably limestone flour. The limestone flour can, for example, also result from the addition of a Portland limestone cement, in particular a CEM II according to DIN EN 197-1:2011-11.

[0082] It may also contain fired clays and / or calcined clays.

[0083] In addition, the fresh concrete mass preferably contains 0 to 9 mass%, preferably 2 to 8 mass%, particularly preferably 3 to 7 mass% of sulfate carriers.

[0084] The aluminum component used for the fresh concrete mix can be aluminum powder, paste, or suspension, as is known per se. The active ingredient content of the aluminum component, based on the total solids, is preferably 0.03 to 0.8 mass%, more preferably 0.05 to 0.6 mass%. As with the admixtures, the solids contained in the aluminum component are not included in the total solids; their content is based on the solids content.

[0085] In addition, an aluminum component or, alternatively, a foam component or a foaming agent is always present. Aluminum components, foam components, and foaming agents are thus used alternatively.

[0086] As already explained, the production of the porous or foam concrete moldings according to the invention is carried out in the usual way, with the ground suspension being added additionally:

[0087] Basically, quicklime and / or hydrated lime, at least one hydrothermally reacting SiO2 component, preferably return sludge, at least one blowing agent or pre-made foam or a foaming agent and water are used to produce the fresh concrete mass as CaO component.

[0088] The preparation preferably proceeds as usual, by first mixing the residual sludge (if present) with the irrigation water, then adding the quartz powder, then the binder (cement, quicklime, hydrated lime), and finally the aluminum component. The suspension according to the invention is also mixed with the irrigation water and (if present) the residual sludge before adding the inert components.

[0089] The fresh concrete mass is poured into a casting mold. If reinforced aerated concrete molds are to be produced, reinforcement can be suspended in the casting mold. Alternatively, the reinforcement can be suspended in the casting mold after the mold has been filled with fresh concrete.

[0090] In the case of the production of aerated concrete moldings, the fresh concrete mass is allowed to expand.

[0091] In the production of foam concrete molds, the foaming process is eliminated. For the production of foam concrete molds, either the fresh concrete mass containing a foaming agent is whipped to form the foam, or the prefabricated foam is mixed in. This occurs before the fresh concrete mass is poured into the mold. The fresh concrete mass is then allowed to set into a green porous or foam concrete cake.

[0092] After stiffening, the aerated or foam concrete cake is cut into individual aerated or foam concrete moldings in a conventional manner.

[0093] The cut porous or foam concrete moldings are then hydrothermally cured in the autoclave in a conventional manner under saturated steam conditions.

[0094] For example, autoclaving is carried out with a holding phase of 6 to 12 hours at a temperature of 180 to 190 °C.

[0095] The start-up and shut-down phases are preferably linear, with no intermediate stop phases. In addition, the start-up and shut-down phases each last, for example, 1.5 to 6 hours. In a very preferred autoclave operating mode, the autoclave begins with a vacuum phase. After the autoclave is closed, the air is pumped out until a negative pressure of, for example, 0.4 bar is reached. This process takes, for example, 20 - 30 minutes. Steam is then fed into the autoclave, and the start-up phase begins. In another preferred operating mode, the air present in the autoclave is reduced by pressureless purging with steam. This process takes, for example, 20 - 40 minutes.

[0096] As already explained, it has been found according to the invention that the fresh concrete mass and the aerated or foamed concrete cake can be easily processed and that the aerated and / or foamed concrete moldings produced according to the invention have good strength properties despite the addition of aerated or foamed concrete grain.

[0097] As already explained, a measure of the strength of aerated and foam concrete forms is the so-called A-number, which indicates the compressive strength relative to the bulk density. The A-number is derived from a mathematical relationship between the compressive strength and the dry bulk density. It represents the relative compressive strength of the aerated or foam concrete form. The higher the A-number, the better the compressive strength level.

[0098] Preferably, the porous or foam concrete moldings according to the invention have an A-number of 900 to 2700 []. The compressive strength is determined for porous or foam concrete moldings with a dry bulk density of 0 to 150 kg / m 3 according to DIN EN 826:2013-05 after drying at 40°C to constant mass and for aerated or foam concrete bodies with a dry bulk density po > 150 kg / m 3 Tested for mass constancy on a cube with an edge length of 100 mm according to DIN EN 772-1: 2011-07 after drying at 70°C.

[0099] Preferably, the porous or foam concrete moldings according to the invention also have a compressive strength of 0.1 to 10.0 N / mm 2 The compressive strength is determined for porous or foam concrete bodies with a dry density of up to 150 kg / m 3 according to DIN EN 826:2013-05 after drying at 40°C to constant mass and for aerated or foam concrete bodies with a dry bulk density po > 150 kg / m 3Tested for mass constancy on a cube with an edge length of 100 mm according to DIN EN 772-1: 2011-07 after drying at 70°C.

[0100] If the porous or foam concrete shaped bodies according to the invention are, preferably unreinforced, porous or foam concrete shaped blocks, they preferably have a compressive strength of 1.0 to 10.0 N / mm 2 , preferably from 1.5 to 8.0 N / mm 2 , particularly preferably from 2.0 to 7.0 N / mm 2 , tested on a cube with an edge length of 100 mm according to DIN EN 772-1 : 2011-07 after drying at 70°C for mass constancy.

[0101] If the porous or foam concrete shaped bodies according to the invention are porous or foam concrete insulating bodies, in particular porous or foam concrete insulating panels, they preferably have a compressive strength of 0.1 to 0.7 N / mm 2 , preferably from 0.1 to 0.5 N / mm 2 , particularly preferably from 0.2 to 0.4 N / mm 2, according to DIN EN 826:2013-05 after drying at 40°C to constant mass.

[0102] In addition, the porous or foam concrete moldings according to the invention preferably have a dry bulk density po of 70 to 800 kg / m 3 , according to DIN EN 772-13: 2000-09 or DIN EN 1602: 2013-05.

[0103] If the aerated or foamed concrete moldings according to the invention are, preferably unreinforced, aerated or foamed concrete molding blocks, they preferably have a dry bulk density po of 151 to 800 kg / m 3 , preferably from 220 to 800 kg / m 3 , particularly preferably from 255 to 600 kg / m 3 , according to DIN EN 772-13: 2000-09.

[0104] If the porous or foam concrete shaped bodies according to the invention are porous or foam concrete insulating bodies, in particular porous or foam concrete insulating boards, they preferably have a dry bulk density po of 70 to 150 kg / m 3 , preferably from 80 to 120 kg / m3 , particularly preferably from 85 to 115 kg / m 3 , according to DIN EN 1602: 2013-05.

[0105] Preferably, the porous or foam concrete moldings also have a thermal conductivity X , dry, unit of 0.039 to 0.180 W / (m K), according to DIN EN 12664: 2001-05 and DIN EN 12667:2001-05.

[0106] If the aerated or foam concrete moldings according to the invention are, preferably unreinforced, aerated or foam concrete molding blocks, they preferably have a thermal conductivity X , dry, unit of 0.060 to 0.180 W / (m K), preferably of 0.065 to 0.160 W / (m K), particularly preferably of 0.070 to 0.140 W / (m K), according to DIN EN 12664: 2001-05 and DIN EN 12667:2001-05.

[0107] If the aerated or foam concrete shaped bodies according to the invention are aerated or foam concrete insulating bodies, in particular aerated or foam concrete insulating boards, they preferably have a thermal conductivity X10, dry, unit of 0.039 to 0.055 W / (m K), preferably of 0.041 to 0.049 W / (m K), particularly preferably of 0.042 to 0.048 W / (m K), according to DIN EN 12664: 2001-05 and DIN EN 12667:2001-05.

[0108] In the following, the invention will be illustrated by means of some embodiments.

[0109] Examples of implementation:

[0110] In the examples, aerated concrete moldings were produced with different recipes.

[0111] The following raw materials were used to conduct the tests:

[0112] Table 1 : Raw materials used

[0113] Table 2: Additive used

[0114] The production of the aerated concrete moldings was always carried out as follows: The test samples were mixed with a dissolver mixer at 550 rpm (disk diameter 12 cm) in a 20 l mixing vessel as follows:

[0115] 1. Place water and, if necessary, the ground or activated suspension in the mixing vessel 2. Add quartz powder, mixing time 30 seconds

[0116] 3. Addition of the binding agents (quicklime, cement), if necessary the aerated concrete grain, mixing time 30 seconds

[0117] 4. Addition of the flow agent

[0118] 5. Add aluminum as a suspension (100 ml), mixing time 20 seconds 6. Pour into a polystyrene container with lid

[0119] The test samples were then demolded after 3 - 4 hours (at 20° C), transferred to the hardening base and subsequently autoclaved.

[0120] The autoclaving started with a vacuum phase lasting 30 minutes, during which a pressure of 0.4 bara bs was reached. The pressure was then increased linearly to 12 bar over 1.5 hours a bs increased, maintained for 7 hours and then, also linearly, reduced to ambient pressure over 1.5 hours.

[0121] Production of aerated concrete aggregates (PBK):

[0122] The production of the aerated concrete aggregates was initially carried out analogously to the production of aerated concrete moldings from the following recipes:

[0123] Table 3: Recipes for the production of the sulfate-containing aerated concrete aggregate PBKSH and the sulfate-free aerated concrete aggregate PBKSF

[0124] The steam-cured aerated concrete specimens were sawn into prisms with maximum dimensions of 40 mm x 50 mm x 500 mm using a band saw. The prisms and any small sawdust residues were crushed in a jaw crusher (Retsch, type BB1). The crushed material was sieved through a 1 mm sieve. The fraction < 1 mm formed the aerated concrete aggregate. A mixed sample was prepared from all small test specimens. The aerated concrete aggregates were not dried. The moisture content was determined according to DIN EN ISO 17892-1:2022-08 and included in the water content of the suspension and the fresh aerated concrete mass.

[0125] Table 4: Results of the measurements of the properties of the starting material of the aerated concrete aggregates

[0126] Production of ground suspension: A suspension was prepared from the previously prepared, undried aerated concrete grains and the quicklime with water, and the suspension was ground.

[0127] The production and grinding took place in a drum mill with the following properties:

[0128] Table 5: Properties of the drum mill and process parameters

[0129] Drum mill

[0130] Manufacturer WELTE a) Grinding technology, Cologne

[0131] Year of construction 1995

[0132] Type designation WGN-WGT 100

[0133] Armor rubber

[0134] Mill diameter 46.5 cm

[0135] Mill length 48 cm

[0136] Rotation speed 48 rpm

[0137] Type of grinding: dry grinding

[0138] Ground material mass as specified

[0139] Grinding balls

[0140] Manufacturer CeramTec GmbH, Plochingen

[0141] Material AI2O3

[0142] Purity 92%

[0143] Classification

[0144] Total grinding mass 70000 g

[0145] Proportion of ball 0 = 40 mm 50%

[0146] Proportion of ball 0 = 30 mm 30%

[0147] Proportion of ball 0 = 20 mm 20 % a) Company liquidation 1998, service by AAM Mahltechnik GmbH, Cologne

[0148] Table 6: Process parameters of the grinding process

[0149] Grinding time fin the mass of grinding material* Starting temperature

[0150] Rule) Ground material

[0151] [min] [g] [°C]

[0152] 120 22500 20 * Total of solids and water (including water from PBK). The particle size distribution of the ground suspensions was determined using laser light diffraction as described above. The ground suspensions all had a particle size of < 100 pm.

[0153] Measurements carried out:

[0154] The dry bulk density of the produced aerated concrete molded bodies was determined according to DIN EN 772-13:2000-09 and the cube crush strength according to DIN EN 772-1:2011-07, and the resulting A-value was calculated. In one case, the thermal conductivity X, dry, unit was also determined according to DIN EN 12664:2001-05 and DIN EN 12667:2001-05.

[0155] In addition, the mineralogical phase composition of several ground suspensions was determined using X-ray diffraction. This was done as follows:

[0156] The suspensions were removed from the mill drum using a spoon. The ground material (10 g) was rinsed, rinsed four times with 5 ml of 2-propanol (AnalaR NORMAPUR, VWR) each time, and filtered for 24 h through hard filter paper (84 g / m 2, No. 1291; Sartorius) under a fume hood. The material was then dried on the filter in a drying cabinet for 24 h at 40°C. For the subsequent wet grinding, 10 wt.% internal standard zincite (ZnO from JT Baker Avantor Performance Materials, Inc.) was added to each sample, corresponding to 1.8 g of substance and 0.2 g of ZnO. Wet grinding in the micron mill (McCrone micronising mill) was carried out in 10 ml of 2-propanol for 4 min in PVC grinding jars with ZrO2 grinding cylinders. The ground material was rinsed, rinsed four times with 5 ml of 2-propanol each (AnalaR NORMAPUR, VWR) and filtered for 24 h on hard filter paper (84 g / m 2, No. 1291; Sartorius) under a fume hood and dried at room temperature (20°C). The powder, brushed off the filter paper and homogenized for 2 minutes in an agate mortar, was pressed into a diffractometer powder tablet (backloading method). A powder tablet was prepared from each sample taken and measured. The samples were measured on a Panalytical MPD Pro diffractometer. Qualitative phase determination was performed using the Panalytical HighScorePlus software. The measurement conditions and further information are listed in Table 7. Table 7: Measurement conditions and further information

[0157] Quantitative determination was performed using the Rietveld method. Bruker AXS Topas (version 5) was used as the analysis software. To determine the amorphous phase fraction, 10 wt.% zinc oxide (see above) was added to the sample as an internal standard and subtracted accordingly during the analysis. The remaining phases, including X-ray amorphous phases, were normalized to 100%.

[0158] The following structures from the ICSD database (Inorganic Crystal Structure Database, as of 2016) were used to evaluate the quantitative phase composition: 11Ä-Tobermorite (# 92943) Quartz (# 34636) Anhydrite (# 15876) Gypsum (# 10101981) Zincite (# 65120)

[0159] Calcite (#18165) Vaterite (#1508970) Portland it (#7020138) CaO (#75785) Ettringite (#16045)

[0160] 1. Series of experiments:

[0161] In the first series of tests, aerated concrete moldings in the density range 350-400 kg / m 3For the production of the aerated concrete fresh masses according to the invention, 10 mass % of

[0162] Aerated concrete aggregates were used, based on the total solids. The fresh aerated concrete mass of the reference aerated concrete molded bodies also contained 10 mass% aerated concrete aggregates.

[0163] In experiment 4R e f the suspension contained only aerated concrete aggregates and no quicklime.

[0164] In addition, sulfate-containing aerated concrete aggregate PBKSH was used for tests 1-4 and sulfate-free aerated concrete aggregate PBKSF was used for tests 5 and 6.

[0165] The ground suspension was prepared as described above.

[0166] The grinding time was 120 minutes each.

[0167] Table 8: Compositions of the recipes of the 1st test series

[0168] *Added in the production moist state, moisture was subtracted from the irrigation water (SH =

[0169] 17.3% humidity, SF = 3.1%) The results of the measurements of the properties of the 1st test series are in

[0170] Table 9 shows the results.

[0171] Table 9: Results of the measurements of the properties of the 1st test series Table 9 clearly shows that the A-number for the inventive aerated concrete bodies 2, 3, and 6 is significantly higher than the A-number of the respective reference aerated concrete body 1 Ref and ÖRef, respectively. The A-number for the inventive aerated concrete bodies 2 and 3 is also higher than the A-number of the reference aerated concrete body 4Ref, in which only the aerated concrete grain was wet-ground without quicklime.

[0172] The addition of 10 mass% aerated concrete aggregate, which was wet-ground together with quicklime before being used to produce the aerated concrete fresh mass, increases the compressive strength level compared to the use of 10 mass% conventional aerated concrete aggregate and also compared to aerated concrete aggregate ground alone.

[0173] 2nd series of experiments:

[0174] In the second test series, 20 mass% aerated concrete aggregate was used.

[0175] In addition, for experiment 10, soft quicklime 4 / 2 was used for the suspension instead of hard quicklime 10 / 1.

[0176] Table 10: Compositions of the recipes of the 2nd test series

[0177] The results of the property measurements of the second test series are shown in Table 11. Table 11: Results of the property measurements of the second test series

[0178] Table 11 clearly shows that the A-number for the aerated concrete moldings 8-10 according to the invention is significantly higher than the A-number of the reference aerated concrete body "Ref." The addition of 20 mass % aerated concrete aggregate, which was wet-ground together with quicklime before use to produce the aerated concrete fresh mass, thus increases the compressive strength level compared to the use of 20 mass % conventional aerated concrete aggregate.

[0179] 3rd series of experiments:

[0180] In the third series of tests, a suspension according to the invention with 75 wt.% sulfate-containing aerated concrete grain PBKSH and 25 wt.% white fine lime 10 / 1, based on the total solids and a W / F value of 2, was produced and wet ground with the mill parameters given above for 60, 120, 180 and 300 minutes.

[0181] In addition, the suspension was mineralogically examined after the specified grinding time and the grain size distribution was determined by laser light diffraction as described above.

[0182] The results of the mineralogical investigations of the third test series are shown in Figure 1. Figure 1 also shows the mineralogical composition of the dry raw mixture (RM) used for the suspension.

[0183] It can be seen that additional calcium carbonate (calcite / vaterite) is formed even after a milling time of 1 hour. Carbonation also increases with increasing milling time. The proportion of hydrated lime (portlandite) resulting from the reaction of the quicklime is also correspondingly lower than if the hydrated lime had not reacted.

[0184] The proportion of amorphous phases also seems to decrease with longer milling times.

[0185] Furthermore, ettringite was formed in all suspensions.

[0186] The formation of calcium carbonate and a reduction in the hydrated lime content were also observed in the suspensions used for test series 1 and 2 (see Figure 2). However, as expected, no ettringite was formed when sulfate-free aerated concrete aggregates were used.

[0187] Table 12 shows the results of particle size distribution measurements for the suspensions after different grinding times. Table 12: Results of particle size distribution measurements

[0188] It can be seen that the maximum grain size for all suspensions is < 100 pm, and the fineness no longer changes significantly after 120 minutes. Finally, it should be noted that all of the mentioned, particularly claimed, features of the process and / or the porous or foam concrete molded body are particularly advantageous, both individually and in any combination, and are the subject of the present invention.

[0189] In addition, the upper and lower limits specified for each individual range can all be combined with one another according to the invention.

Claims

Claims 1. A process for producing hydrothermally cured aerated or foamed concrete moldings, comprising the following process steps: a) Producing a fresh concrete mass using at least one hydrothermally reacting SiO2 component, quicklime and / or hydrated lime, at least one aerated and / or foamed concrete grain, water and at least one blowing agent or prefabricated foam or a foaming agent, b) Optionally foaming the fresh concrete mass containing the foaming agent by stirring, c) Pouring the ready-to-cast fresh concrete mass into a casting mold, d) Optionally allowing the fresh concrete mass containing the blowing agent to expand, e) Allowing the fresh concrete mass to stiffen to form a aerated or foamed concrete cake, f) Cutting the aerated or foamed concrete cake into individual aerated or foamed concrete moldings, g) Curing the aerated or foamed concrete moldings in an autoclave,characterized by the following process steps: h) producing a suspension comprising at least a portion of the porous and / or foamed concrete grain used, at least a portion of the quicklime used and / or at least a portion of the hydrated lime used and at least a portion of the water used, i) grinding the suspension, j) mixing the ground suspension with the other components of the fresh concrete mass.

2. Method according to claim 1, characterized in that the suspension is ground to a grain size < 100 pm, determined by laser light diffraction according to ISO 13320:2020-01 on the dried suspension.

3. Method according to claim 1 or 2, characterized in that the porous or foam concrete grains are crushed when the suspension is ground.

4. Process according to one of the preceding claims, characterized in that the suspension is ground to a dgo value of 20 to 55 pm, preferably 25 to 40 pm, and / or a dso value of 2 to 10 pm, preferably 3 to 6 pm, determined by laser light diffraction according to ISO 13320:2020-01 on the dried suspension.

5. Process according to one of the preceding claims, characterized in that the suspension is prepared with a W / F value of 0.3 to 3.0, preferably 0.5 to 3.0, more preferably 1.0 to 2.5, particularly preferably 1.6 to 2.

2.

6. Process according to one of the preceding claims, characterized in that the proportion of porous and / or foam concrete grains in the suspension is 50 to 90 mass%, preferably 70 to 80 mass%, based on the dry mass of all solids used to produce the suspension.

7. Method according to one of the preceding claims, characterized in that the entire proportion of the porous and / or foam concrete grain used to produce the porous or foam concrete molded body is used to produce the suspension.

8. Method according to one of the preceding claims, characterized in that only a part of the quicklime and / or lime hydrate used to produce the aerated or foam concrete molded body is used to produce the suspension.

9. Method according to one of the preceding claims, characterized in that 10 to 35 mass%, preferably 10 to 30 mass%, particularly preferably 10 to 25 mass%, very particularly preferably 15 to 25 mass%, based on the solids content of the fresh concrete mass, of porous or foam concrete grains are added via the suspension.

10. Method according to one of the preceding claims, characterized in that the porous and / or foam concrete grain used for the production of the suspension has a dgo value < 10 mm, preferably < 5 mm, particularly preferably < 2 mm, determined by means of the sieve passage according to DIN EN 1015-1:2007-05.

11. Method according to one of the preceding claims, characterized in that the porous and / or foam concrete grain used for the production of the suspension has a maximum grain size of < 12 mm, preferably < 6 mm, particularly preferably < 3 mm, determined by means of the sieve passage according to DIN EN 1015-1:2007-05.

12. Method according to one of the preceding claims, characterized in that the porous and / or foam concrete grain used for the production of the suspension has a coarse grain fraction comprising grains with a grain size > 125 pm, preferably grains with a grain size > 250 pm, determined by means of the sieve passage according to DIN EN 1015-1:2007-05.

13. Process according to one of the preceding claims, characterized in that the grinding of the suspension takes place in a mill, preferably in a drum mill, preferably in the form of a ball mill and / or rod mill, and / or in a roller mill.

14. Method according to one of the preceding claims, characterized in that Portland cement clinker is used as SiO2 and CaO component for the production of the fresh concrete mass, wherein the fresh concrete mass preferably has a Portland cement clinker powder content of 5 to 45 mass%, preferably 10 to 40 mass%, particularly preferably 15 to 35 mass%, based on the solids content of the fresh concrete mass.

15. Method according to one of the preceding claims, characterized in that quartz is used as the SiO2 component for the production of the fresh concrete mass, wherein the quartz preferably makes up the predominant proportion of SiO2 in the fresh concrete mass.

16. Method according to claim 15, characterized in that For the production of the fresh concrete mass, 25 to 70 mass%, preferably 35 to 60 mass%, quartz, based on the solids content of the fresh concrete mass, may be used.

17. A method according to any one of the preceding claims, characterized in that 5 to 40 mass%, preferably 5 to 30 mass%, particularly preferably 10 to 25 mass%, of quicklime and / or hydrated lime, based on the solids content of the fresh concrete mass, are used for the production of the fresh concrete mass.

18. Method according to one of the preceding claims, characterized in that return sludge is used for the production of the fresh concrete mass, wherein the fresh concrete mass preferably has a return sludge content (dry mass) of 2 to 30 mass%, preferably 2 to 20 mass%, preferably 5 to 15 mass%, based on the solids content of the fresh concrete mass.

19. Method according to one of the preceding claims, characterized in that a fresh concrete mass is produced with a water / solids ratio of 0.5 to 1.2, preferably 0.5 to 1.1, particularly preferably 0.6 to 0.9, most particularly preferably 0.6 to 0.

8.

20. Method according to one of the preceding claims, characterized in that all components mixed for the production of the fresh concrete mass have a grain size of < 1 mm, preferably < 500 pm, particularly preferably < 150 pm. 21 . Method according to one of the preceding claims, characterized in that Porous or foam concrete moldings with a thermal conductivity Xio, dry, unit of 0.039 to 0.180 W / (m K) can be produced.

22. Method according to one of the preceding claims, characterized in that Porous or foam concrete moldings with a dry bulk density po of 70 to 800 kg / m 3 , according to DIN EN 772-13: 2000-09.

23. Method according to one of the preceding claims, characterized in that Porous or foam concrete moldings with a compressive strength of 0.1 to 10.0 N / mm 2 , are manufactured.

24. Method according to one of the preceding claims, characterized in that Porous or foam concrete moldings with an A number of 900 to 2700 [] can be produced.

25. Method according to one of the preceding claims, characterized in that Aerated or foam concrete blocks a) with a thermal conductivity X , dry, unit of 0.060 to 0.180 W / (m K), preferably of 0.065 to 0.160 W / (m K), particularly preferably of 0.070 to 0.140 W / (m K), according to DIN EN 12664: 2001-05, and / or b) with a dry bulk density po of 151 to 800 kg / m 3 , preferably from 220 to 800 kg / m 3 , particularly preferably from 255 to 600 kg / m 3 , according to DIN EN 772-13: 2000-09, and / or c) with a compressive strength of 1.0 to 10.0 N / mm 2 , preferably from 1.5 to 8.0 N / mm 2 , particularly preferably from 2.0 to 7.0 N / mm 2, tested on a cube with an edge length of 100 mm after drying at 70°C for mass constancy in accordance with DIN EN 772-1 : 2011-07.

26. Method according to one of claims 1 to 24, characterized in that a) aerated or foam concrete insulation bodies with a thermal conductivity X , dry, unit of 0.039 to 0.055 W / (m K), preferably of 0.041 to 0.049 W / (m K), particularly preferably of 0.042 to 0.048 W / (m K), according to DIN EN 12667:2001-05, and / or b) aerated or foam concrete insulation bodies, in particular aerated or foam concrete insulation boards, with a dry bulk density po of 70 to 150 kg / m 3 , preferably from 80 to 120 kg / m 3 , particularly preferably from 85 to 115 kg / m 3 , according to DIN EN 1602: 2013-05, and / or c) aerated or foam concrete insulation bodies, in particular aerated or foam concrete insulation boards, with a compressive strength of 0.1 to 0.7 N / mm 2 , preferably from 0.1 to 0.5 N / mm 2 , particularly preferably from 0.2 to 0.4 N / mm 2, according to DIN EN 826:2013, and conditioning at 40°C to constant mass.

27. Hydrothermally cured porous or foam concrete body comprising a solid web framework surrounding pores resulting from a foam or produced by a blowing process, wherein the solid web framework comprises calcium silicate hydrate phases and micropores, characterized in that the porous or foam concrete molded body is produced by a process according to one of claims 1 to 26 and preferably has the features of at least one of claims 21 to 26.

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