DE102020112292A1 - Process for the production of a foam concrete mixture for the production of highly deformable foam concrete products, highly deformable foam concrete products and their use - Google Patents

Abstract

A method for producing a foam concrete mixture for the production of highly deformable foam concrete products with providing a foam concrete mixture comprising binders (212), foaming agents (232) and granules, with: establishing a required minimum compressive strength (110); Establishing a required minimum deformability (120); Determining (130) depending on the required minimum compressive strength and the required minimum deformability percentage of at least the following substances: binding agent (212), foaming agent (232) and grain groups of the granulate according to a grading curve (214), and providing and mixing the determined percentage of at least the Binder (212), the foaming agent (232) and the grain groups of the granulate according to a grading curve (214) as a foam concrete mixture (140).

Description

Field of invention

The invention relates to a method for producing a foam concrete mixture for the production of highly deformable foam concrete products, highly deformable foam concrete products and their use.

State of the art

Deformable components and their various applications are known in tunnel construction. In particular, deformable components are used in tunnel construction for temporary expansion in order to reduce loads that can arise from pressure-sensitive or swellable rock by means of deformation. Deformable components can have different geometries and properties. Beam-shaped components or flat systems are used in tunnel construction. Deformable components and systems that are used can consist of different materials or material combinations, for example steel, concrete or mortar.

For example, hiDCon® elements are available from Solexperts AG, Switzerland, which are deformable. However, in some applications, even more extensive deformability or even more extensive predictability of the deformation behavior may be desirable.

Disclosure of the invention

The object of the invention is to provide a method for producing the foamed concrete mixture for the production of improved highly deformable foamed concrete products and improved highly deformable foamed concrete products, the foamed concrete products mentioned or their uses in particular having improved deformation properties.

The object is achieved with a method according to claim 1 and devices according to independent claims. Advantageous developments and embodiments emerged from the subclaims and from this description.

One aspect of the invention relates to a method for producing a foam concrete mixture for the production of highly deformable foam concrete products with the provision of a foam concrete mixture comprising binders, foaming agents and granules, with: determining a required minimum compressive strength, determining a required minimum deformability, determining percentage proportions of at least the following substances: binding agent, Foaming agents and grain groups of the granulate according to a grading curve depending on the required minimum compressive strength and the required minimum deformability, and providing and mixing the determined percentage of at least the binder, the foaming agent and the grain groups of the granulate as a foam concrete mixture.

Typical embodiments of the highly deformable foam concrete products described here have largely predictable or definable deformation properties after overcoming their elastic deformation range over a comparatively large plastic deformation range.

In embodiments, the method comprises establishing a required minimum compressive strength, in particular establishing a minimum compressive strength under the action of tension. In the context of this application, the term “tension” encompasses mechanical tension, in particular mechanical compressive tension. For example, stress in the foam concrete product can be caused by rock stress of a pressing rock.

Typically, the minimum compressive strength of a foam concrete is determined here DIN EN 12390-3 defined, in particular analogously in a pressure test DIN EN 12390-3 defined, i.e. tested in compression tests on cylinders, cubes or drill cores of foam concrete at the age of 7 days, 21 days or 28 days. In particular, the minimum compressive strength of a foam concrete is after DIN EN 12390-3 , especially in a pressure test analogously DIN EN 12390-3 , be tested on a cube with at least 100 mm, for example 200 mm edge length. For this, the minimum compressive strength of a foam concrete under a uniaxial stress state or a multidimensional Stress state, for example under a three-dimensional stress state, can be checked. Typically the minimum compressive strength is 0.5 MPa, 5 MPa or 10 MPa. In the present disclosure, the term “uniaxial” refers to a compression test without lateral support of the specimen. The terms “three-dimensional” or “multi-dimensional” refer to a pressure test with lateral support of the specimen on all sides.

Typically, the method includes establishing a required minimum deformability. For example, deformability or deformation of a material in a compression test can analogously DIN EN 12390-3 be measured. After DIN EN 12390-3 only the minimum compressive strength is tested; the standard test then typically ends after the first break. The term “first break” is typically used to describe a first stress maximum after which a stress drop can be observed in the test due to plastic deformation processes or breaks in the material. A minimum deformability is not dealt with in this standard. To measure the minimum deformability, the test is typically continued over the range specified by the standard. The term “minimum deformability” can refer to a plastic deformation range that lies between the elastic limit and the breaking limit of the foam concrete product. In the case of typical foam concrete in accordance with aspects of the invention, a different behavior compared to standard concrete with regard to the fracture behavior can be observed. After the first break, the force or tension does not drop to a massively low value, but remains at a high level, typically at least 50%, at least 60% or at least 70% of the tension at the first break.

Conventional concrete, which is described in the standards, reaches the maximum compressive strength in the uniaxial compression test after a very small deformation or elongation of the test body. The elongation is in the per thousand range, according to the standard at around 2 ‰. After the maximum compressive strength has been reached, the stress or force that can be absorbed in the test specimen drops sharply with further deformation, typically a drop of> 50% in compressive strength. In the case of the foam concrete described here, the behavior is different. In the uniaxial compression test, a maximum of compressive strength is achieved after a slight deformation, analogous to conventional concrete technology. In contrast to conventional concrete, the subsequently absorbable tension does not drop to a comparable extent (e.g. between 5 - 40%), but the tension can be maintained through permanent forced deformation. The tension is at least substantially maintained if the forced deformation is continued or maintained. The lowest value reached here defines the minimum compressive strength. The minimum compressive strength described herein for typical embodiments is significantly lower than that of a foam concrete with comparable cement, foam and aggregate proportions. This can be explained by the fact that additional pore volume is introduced in particular through the porous aggregate. Aggregates such as sand usually do not contain this pore volume. By using a grading curve optimized as described herein, the additional proportion of pores can be further maximized.

The minimum deformability describes the range in which, with increasing deformation, the absorbable stress of the test specimen is below the maximum compressive strength but above the minimum compressive strength. Deformability is not defined in conventional concrete technology in connection with pressure loads, since the expansion that occurs should always be in the elastic range. With increasing deformation, the stress increases continuously and exceeds the maximum compressive strength that was reached at the beginning of the deformation. This behavior can be described with an elastic, plastic, bi-linear material model, where E _{T is} not constant.

Typical methods include determining percentages of at least the following substances for the foam concrete mixture: binders, foaming agents and granules, in particular grain groups of the granules according to a grading curve, depending on the required minimum compressive strength and the required minimum deformability. The minimum deformability can be adjusted via the composition of the grading curve and the pore volume it contains. A high proportion of a small fraction increases the minimum compressive strength and reduces the deformability.

Typically, highly deformable foam concrete, in particular highly deformable foam concrete products, is produced with one of the typical foam concrete mixtures described herein. Typical foam concrete products have an increased air void content, in particular of generally more than 20% by volume or more than 30% by volume. Typical foam concrete products described herein do not resemble concrete DIN EN 206-1 / DIN 1045-2 . Typical foamed concrete products according to aspects of this invention also correspond to non-typical conventional foamed concrete which conventionally is not Has grain groups. Typical foamed concrete products according to the invention comprise groups of grains with at least a proportion which has larger grains than sand.

Typically, the term “highly deformable” in relation to a foam concrete product means that the foam concrete product is subjected to a compression test DIN EN 12390-3 , especially by analogy DIN EN 12390-3 , without lateral support of the specimen, in particular after overcoming an elastic limit, at 50% deformation a compressive stress of less than 200% of the minimum compressive strength, preferably at 55% deformation a compressive stress of less than 250% of the minimum compressive strength and more preferably at 60% deformation a compressive stress of shows less than 350% of the minimum compressive strength. In the compression test, in typical embodiments, the compressive strength measured in the same test or in a further test on the same foam concrete product can be used instead of the minimum compressive strength.

The term “highly deformable” typically means, in relation to a foam concrete product, that a typical foam concrete product described herein after 35% deformation in a compression test DIN EN 12390-3 , especially by analogy DIN EN 12390-3 , without lateral support or with lateral support of the specimen on all sides, a compressive stress of less than 200% of the minimum compressive strength, preferably with 40% deformation a stress of less than 300% of the minimum compressive strength and more preferably with 45% deformation a stress of less than 500% shows the minimum compressive strength. In the compression test, in typical embodiments, the compressive strength measured in the same test or in a further test on the same foam concrete product can be used instead of the minimum compressive strength.

The binder is typically cement or suitable synthetic resin mortar, typically fire-safe or fire-retardant synthetic resin mortar. Typically, drinking water or naturally occurring water is used as the added water.

Typically, cement or a cement paste is used as the basis for preparing a foam concrete mix. Typically, cement paste comprises a binding agent, in particular cement, added water and possibly additives. Thus, a foam concrete mixture can be produced with the further addition of a separately prefabricated foam made of foaming agent, in particular with the further addition of a separately prefabricated foam made of a mixture of foaming agent and water for foam formation and possibly additives. The water for the foam formation can be taken from the added water or measured in addition to the added water, i.e. not counted towards the amount of the added water. Typically, the physical foaming used to produce the foam concrete or foam concrete mixture does not require any blowing agent or the production is typically carried out without blowing agent. Typical processes are thus in contrast to other processes with chemical foaming, for example with the addition of substances that react with the release of gases in or with the cement paste and thus form pores. Alternative typical methods for producing the foam concrete or foam concrete mix additionally use chemical blowing agents.

Typically, a foam concrete mixture is formed by introducing foam filled with air or with other gases from foaming agent or from a mixture of foaming agent and water, for example into a cement paste. Typically, only inert gases are used for foam formation or are introduced into a mixture of foaming agent and water, for example nitrogen, argon or helium. This can be advantageous in particular when used in connection with final storage sites for nuclear waste or in applications which are sensitive to oxygen. The pressure of the air or other gases introduced is typically a maximum of 5 bar, typically a maximum of 3 bar, or typically a maximum of 1.5 bar or typically at least 0.3 bar.

In the case of physical foams, similar to chemical foams, the gas bubbles generated with the foaming agent can only serve temporarily as a supporting body until a stable solid structure of the foam concrete mixture has formed during curing or drying.

Typically, cement is an inorganic, finely ground hydraulic building material. For example, cement is made by burning the starting materials limestone, sand or clay or mixtures of these materials at the sintering limit of around 1,450 ° C. In the context of the present disclosure, a hydraulic building material is a building material which, after the addition of water, independently solidifies and hardens as a result of chemical reactions with the added water and, after hardening, is solid and stable under water remains. From a chemical point of view, cement can mainly contain calcium silicate with proportions of aluminum and iron compounds.

In the context of the present disclosure, portland cement (CEM I), portland composite cement (CEM II), blast furnace cement (CEM III or VLH III), pozzolan cement (CEM IV or VLH IV), or composite cement (CEM V or VLH V), in particular according to the types of cement after DIN EN 197-1 or DIN EN 14216 , be suitable as a binder. Portland cement is typically made by grinding clinker and gypsum or anhydrite. For example, for typical processes described herein, a Portland cement with approx. 58 to 66% calcium oxide (CaO), 18 to 26% silicon dioxide (SiO ₂ ), 4 to 10% aluminum oxide (Al ₂ O ₃ ) and 2 to 5% iron oxide (Fe ₂ O ₃ ) can be used.

The foaming agent is typically a surfactant, proteins or enzymes or mixtures thereof. Protein-based foaming agents typically have a high level of stability. The choice of surfactant or proteins can influence the cement chemistry and the rheological properties of the cement paste or foam concrete mixture. In particular, the high ion concentration and the high pH value in a foam concrete mixture can reduce or suppress the foaming effect of many surfactants or proteins.

In the context of the present disclosure, suitable proteins are typically those that have negative charges in the alkaline cement paste. In typical processes, such proteins are used to create a close connection between the loosened protein strands, so that the foam stability is increased. For example, the foaming agent can have a protein, in particular a hydrolyzed protein or protein fractions, which are in particular 50% by mass, 70% by mass or 90% by 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 molar mass between 20,000 and 120,000 Daltons. The remaining 10% by mass, 30% by mass or 50% by mass can be other amino acids, in particular other anionic amino acids.

In principle, particularly strongly foaming alkali-stable or alkaline-reacting surfactants are particularly suitable as surfactants. A high foaming power is typically important here. Anionic surfactants and in particular sulfonates, alkyl sulfonates, in particular alkali alkyl sulfonates, alkylene sulfates or alkyl ether sulfonates are preferred. The alkyl chains or alkylene chains of the sulfonates and sulfates are in particular long-chain and more preferably unbranched. Chain lengths greater than or equal to C8 and in particular between C10 and C20 can be regarded as typical.

Preferred surfactants include i.a. linear alkylate sulfonates, alpha olefin sulfonates, beta olefin sulfonates, alkyl ether sulfates, ethoxylated alkyl phenols. Typical surfactants that are used are alpha olefin sulfonates, e.g. B. sodium C14-16 olefin sulfonate, among the alkyl sulfates SDS and SLS and / or certain alkali, ammonium or ethanolamine salts of sulfuric acid esters of alkoxylated alcohols.

Other anionic surfactants that can be used are acylamino acids and their salts, including acyl glutamates, such as sodium acyl glutamate, Di-TEApalmitoyl aspartate, sodium caprylic / capric glutamate or sodium cocoyl glutamate, acyl peptides, sarcosinates, taurates, acyl lactylates, arginates, alinolines, acyl lactylates, arginates, alinates Propionates, lactylates, and amide carboxylates. Typically, phosphates / phosphonates can be considered. Further examples are sulfosuccinates, sodium cocomonoglyceride sulfate, sodium lauryl sulfoacetate or magnesium PEG-n-cocoamide sulfate, alkylarylsulfonates and acyl isethionates, ether and ester carboxylic acids, preferably fatty acids, and other known foaming anionic surfactants such as are commercially available.

In typical embodiments it is provided that the ionic foam-forming surfactant contains or consists of at least one anionic surfactant or consists exclusively of anionic surfactants or exclusively anionic surfactants are used. A single surfactant or a mixture of several surfactants can be used. In a mixture of further typical embodiments, in addition to at least one anionic surfactant, at least one other, in particular nonionic surfactant can be included. In particular, Sika ^® Lightcrete-400 with a density of 1.07 kg / L can be used as a foaming agent in typical embodiments.

In typical embodiments of the invention, a foam concrete mixture contains at least 10 g, at least 30 g, at least 50 g, at least 75 g or at least 100 g or a maximum of 3 kg, a maximum of 2 kg or a maximum of 1 kg of the foaming agent based on 1 m ³ of the foam concrete mixture.

In the context of the present disclosure, the term “aggregates” can include granules, fibers or mixtures thereof. The term "additives" can include limestone powder, pigments, or mixtures thereof. The term “additive” can include concrete plasticizers, retarders, setting accelerators, hardening accelerators, flow agents, sealants, organic and inorganic stabilizers or mixtures thereof. For this purpose, an additive can be added to a foam concrete mixture or a cement paste, a binder or a foaming agent.

Typical granules, which are used in the context of embodiments, consist of a natural granule from mineral deposits, an artificial granule or a combination of these two. For example, granules comprise or consist of natural granules such as pumice, tuff, lava sand, lava gravel, kieselguhr, vermiculite or mixtures thereof. A typical granulate consists of or comprises artificial granulate such as expanded slate, expanded clay, expanded glass, expanded mica, expanded perlite, coal fly ash, brick chippings, slag pumice (slag pumice), ceramic, plastic and boiler sand or mixtures thereof. In the context of the present disclosure, a granulate made of expanded glass can be a foam glass granulate.

In typical embodiments of the invention, granules comprise or consist of foam glass granules, expanded clay granules, clay granules, vermiculite granules or mixtures thereof. Typical granules used in embodiments are porous. Typically, a foam glass granulate can be a mineral lightweight building material, which is made in particular from pure waste glass. In particular, the foam glass granulate consists of closed-pore foam glass granulate, which typically has an essentially spherical grain shape. Alternatively, broken foam glass is used. For this purpose, foam glass can be the name for a solidified expanded glass with air-tight closed cells which are in particular filled with gas. Typically, the gas composition in the pores or honeycombs can depend on the manufacturing process. In particular, at least partially Poraver ^{®, ®} Liaver or mixtures exclusively in typical embodiments, these two or used as granules.

In typical embodiments, the granules are at least substantially spherical. “Essentially spherical” typically means a grain shape with an average diameter ratio of largest to smallest diameter, in particular average largest diameter to average smallest diameter, of less than 9: 1, less than 6: 1, less than 3: 1, less than 2 : 1 or less than 1.5: 1, in particular less than 1.3: 1. Typically, the term “granules” refers to granular solids. The term "substantially spherical" can mean that more than 50%, more than 75%, or more than 90%, or all of the grains correspond to a specific maximum average diameter ratio.

Typical grains have an average diameter in the range of at least 0.02 mm, at least 0.03 mm or at least 0.04 mm or up to 10 mm, up to 8 mm or up to 4 mm. An average diameter of the spherical grains of the present disclosure can typically be determined by applying a laser diffraction method according to ISO 13320: 2009, a SEM (scanning electron microscopy) image analysis method according to ISO 13322-1: 2014, or a sieve analysis device according to ISO 6274: 1982.

Typically, the granulate is divided into grain groups. In particular, the grain groups can be defined by specifying two limiting sieves (d _min and d _max ).

In the context of the present disclosure, d _min can be defined as the screen size of the lower limiting sieve or the diameter of the smallest grain of a grain group or a grain mixture or granulate in mm. For this purpose, dmax can be defined as the mesh size of the upper limiting sieve or the diameter of the largest grain of a grain group or a grain mixture or granulate in mm. Typically, the grain groups of the granulate can be at least one of the grain groups with the limiting sieve (d _min / d _max ) 0.25 / 0.5 mm, 0.5 / 1 mm, 1/2 mm, 2/4 mm, 4/6 mm and 4/8 mm. In particular, the ratio of the screen widths of the lower and upper limiting sieves of the grain groups is not less than 1.4.

Typically, sieving to check the grain composition according to DIN EN 933 part 1 and part 2 be carried out. Grain groups which are used in embodiments typically have a grain group minimum compressive strength, in particular an average grain group minimum compressive strength of 0.5 MPa, preferably 1.0 MPa and more preferably 1.5 MPa. A grain group minimum compressive strength, in particular an average grain group minimum compressive strength, can typically according to DIN EN 13055-1 to be determined. In particular, the percentages of the Grain groups of the granulate depending on the required minimum compressive strength and the required minimum deformability by selecting grain groups with a certain grain group minimum compressive strength or certain limiting sieves. In typical embodiments, the required minimum compressive strength and the required minimum deformability in a foam concrete or foam concrete product produced with the foam concrete mixture are achieved in this way.

In typical embodiments, the percentage of at least the grain groups of the granulate are determined as a function of the required minimum compressive strength, taking into account the respective average compressive strength of the respective grain group. In typical exemplary embodiments, the minimum compressive strength of a foam concrete product produced later can be calculated or estimated when determining the percentage of the grain groups by weighting the compressive strengths of the respective grain groups according to their percentage shares, in particular volume shares, and thus calculating an overall compressive strength becomes. This calculation can include the compressive strength and the volume of the binder in the foam concrete product, as well as the volume of the voids formed with the foaming agent (compressive strength zero).

For production, the volume fractions are typically converted into weight fractions to make the fractions easier to provide. The calculation of the grain pattern is based on the volume proportions, since typically the mechanical properties such as strength or yield strength can be estimated according to the area and thus the volume proportions in the finished product. The binder is typically included in an initial calculation and may not be included in subsequent calculations.

Typically, the percentages of the binder, the foaming agent and the grain groups of the granulate are determined iteratively according to a grading curve. In the context of the present disclosure, the term "iterative" stands for step-by-step and repeated calculations to determine the percentage of at least the following substances: binders, foaming agents and grain groups of the granules up to the required minimum compressive strength through the weighted, in particular volume-weighted average of the compressive strengths of the respective percentage shares is achieved.

The minimum deformability can be estimated from the volume of the foamed foam. Typically, the minimum deformability corresponds to 0.8 to 0.9 times the volume fraction of the foamed foam or the volume fraction of the pores in the finished product.

auftragen lässt, wobei:

• - V_Zementleim das Volumen des Zementleims ist,
• - V_gesamt das Volumen der Schaumbetonmischung mit aufgeschäumtem Schaum ist,
• - U_Granulat das Volumen des Granulates ist,
• - U_Schaum das Volumen des aufgeschäumten Schaumes ist,
• - D_Schaumbeton die geforderte Mindestdruckfestigkeit des Schaumbetons ist,
• - D_Zementleim die Druckfestigkeit des Zementleims ist, und
• - D_Granulat die Druckfestigkeit des Granulats ist.

Typically, the percentage of the binder, the foaming agent and the grain groups of the granulate is determined according to the equation $${\mathrm{D.}}_{\mathrm{S.}cHaumbetOn}=\left(\frac{V_{Zementleim}}{V_{Gesamt}}\right).{\mathrm{D.}}_{Zementleim}+\left(\frac{V_{Granulat}}{V_{Gesamt}}\right).{\mathrm{D.}}_{Granulat}+\left(\frac{V_{\mathrm{S.}cHaum}}{V_{Gesamt}}\right).0$$

can be applied, whereby:

• - V _{cement paste is} the volume of the cement paste,
• - V _{total is} the volume of the foam concrete mix with foamed foam,
• - U _{granulate is} the volume of the granulate,
• - U _{foam is} the volume of the foamed foam,
• - D _{foam concrete is} the required minimum compressive strength of the foam concrete,
• - D _{cement paste is} the compressive strength of the cement paste, and
• - D _{granulate is} the compressive strength of the granulate.

If the granulate comprises several grain groups with different compressive strengths, the compressive strengths are typically weighted according to the volume proportions of the grain groups in the above equation in the term of the compressive strength of the granulate. Typically, a calculated or determined compressive strength of the granulate is a weighted average of the typical compressive strengths of all grain groups of the granulate in a foam concrete mixture, for example specified by the manufacturer.

Typically, determining the percentage of the grain groups of the granulate according to a grading curve as a function of the required minimum compressive strength and the required minimum deformability includes stipulating the number of grain groups in the granulate. Typically, the granulate consists at least essentially of percentages of a plurality of grain groups. The granules typically consist of percentages of at least two or at least three different grain groups.

For example, in order to achieve a desired packing density of the granulate in the foam concrete mixture, the percentage of the grain groups is calculated using a grading curve. The grading curve used typically deviates from a Fuller grading curve. For example, in order to achieve a high degree of deformability, in embodiments the aim is for the granulate to be as dense as possible. In order to achieve as dense a grain structure as possible from several selected grain groups of a granulate, percentages of a plurality of grain groups of a granulate are compiled using a grading curve.

Typically, a grading curve is a transition or cumulative curve, by means of which the grain size distribution or grain composition of a granulate is graphically represented. The grain sizes can be plotted on the horizontal axis (abscissa) of a grading curve diagram, and the percentage of the respective sieve passes or grain sizes on the vertical axis (ordinate).

Typical processes use a grading curve, which is called the ideal grading curve in technical terms, or which ensures a dense grain structure in which the amount of glue required to fill the gaps between the grains is low. With grading curves typically used, the surface area of the grains is minimized in relation to the volume of the grains in order to minimize the cement required to coat the grains.

wobei:

• - A der Siebdurchgang in M.-% (Massenanteil) ist, der durch das Sieb mit dem Durchmesser d hindurchgeht,
• - d der Durchmesser oder durchschnittliche Durchmesser mit einem Wert zwischen 0 und d_max ist, für den der prozentuale Anteil in einem Korngemisch, Granulat berechnet werden soll,
• - d_max der Durchmesser des Größtkorns der zu berechnenden Sieblinie, und
• - n der Exponent zur Berücksichtigung der Kornform ist.

A grading curve used by typical processes can be a Fuller grading curve. Typical Fuller grading curves correspond to the equation $$\mathrm{A.}=100\ast \left(\frac{d}{d_{max}}\right){\begin{array}{c}n\\ \end{array}}_{,}$$

in which:

• - A is the sieve passage in M .-% (mass fraction) that passes through the sieve with the diameter d,
• - d is the diameter or average diameter with a value between 0 and d _max , for which the percentage in a grain mixture, granulate is to be calculated,
• - d _{max is} the diameter of the largest grain of the grading curve to be calculated, and
• - n is the exponent for taking the grain shape into account.

Typically, in the method according to the invention, a sphere is assumed as the grain shape. Typically, the exponent n is set at at least 0.3, at least 0.35 or in particular at least 0.4 and at most 0.47, at most 4.5 or in particular at most 0.43.

In typical embodiments of the invention, the percentages are calculated using a non-Fuller grading curve. Typical embodiments use a grading curve which, compared with a Fuller grading curve, has a reduced proportion of small grain sizes. A typical grading curve that is used in embodiments is a Funk-Dinger grading curve. A Funk-Dinger grading curve shows a reduced proportion of small grain sizes compared to a comparable Fuller grading curve. However, other grading curves with a proportion of small grains that is reduced compared to a Fuller grading curve can also be used in typical embodiments.

The term “reduced proportion of small grain sizes” typically means that in the grain groups of the granules less than 10%, typically less than 5%, typically less than 2%, typically less than 1% or typically at least essentially 0% grains with a diameter less than 250 µm, less than 100 µm, or less than 50 µm. The term "essentially 0% grains" typically means that only unavoidable residues of grains with a Diameters smaller than 250 µm, less than 100 µm or less than 50 µm are present. Unavoidable residues can arise, for example, during production or typically be present in material supplied by a manufacturer.

In typical embodiments of the invention, the percentages of a plurality of grain groups are calculated using a grading curve, at least essentially according to the Funk-Dinger grading curve.

auftragen lässt, wobei:

• - A der Siebdurchgang in M.-% (Massenanteil) ist, der durch das Sieb mit dem Durchmesser d hindurchgeht,
• - d der Durchmesser oder durchschnittlicher Durchmesser mit einem Wert zwischen d_min und d_max ist, für die der prozentuale Anteil in einem Korngemisch, Granulat berechnet werden soll,
• - d_max der Durchmesser des Größtkorns ist, die zu berechnenden Sieblinie,
• - d_min der Durchmesser des Kleinstkorns ist, die zu berechnenden Sieblinie, und
• - n der Exponent zur Berücksichtigung der Kornform ist.

Typically, a Funk-Dinger grading curve is a curve that follows the equation $$\mathrm{A.}=100\ast \frac{\left(d^n-d_{min}^n\right)}{\left(d_{max}^n-d_{min}^n\right)}$$

can be applied, whereby:

• - A is the sieve passage in M .-% (mass fraction) that passes through the sieve with the diameter d,
• - d is the diameter or average diameter with a value between d _min and d _max , for which the percentage in a grain mixture, granulate is to be calculated,
• - d _{max is} the diameter of the largest grain, the grading curve to be calculated,
• - d _{min is} the diameter of the smallest grain, the grading curve to be calculated, and
• - n is the exponent for taking the grain shape into account.

Typically, a Funk-Dinger grading curve takes an ideal sphere into account as the grain shape. In particular, the corresponding exponent n for this grain shape for the Funk-Dinger grading curve is 0.37.

Typically, the determination of the percentage of the grain groups of the granulate according to a grading curve includes a calculation of the bulk volume and the grain volume of the grain groups of the granulate on the basis of the quantities of bulk density and gross grain density. The bulk density of the grain groups used is typically between 125 kg / m ³ and 500 kg / m ³ , typically between 150 kg / m ³ and 475 kg / m ³ , typically between 170 kg / m ³ and 450 kg / m ³ . Typical grain densities of grain groups are between 250 kg / m ³ and 1100 kg / m ³ , typically between 275 kg / m ³ and 1050 kg / m ³ , typically between 300 kg / m ³ and 1000 kg / m ³ .

Typically, determining the percentage of the grain groups of the granulate according to a grading curve includes calculating the pore space, calculating a water-binding agent value, in particular calculating a water-cement ratio, calculating an amount of binding agent, in particular calculating an amount of cement, calculating an amount of water added or calculating a glue density the foam concrete mix.

For example, the pore space of a foam concrete mixture can be calculated by using the bulk volume and grain volume of the percentage of the several selected grain groups of the granulate. The term pore space refers to the space that is present in the foam concrete mixture without the addition of foaming agents.

In typical embodiments, the mixing of the proportions in order to obtain the foam concrete mixture takes place by means of a compulsory mixer, a free-fall mixer, a truck mixer or a planetary mixer with or without a vortex. For example, the mixing of the proportions of the binding agent, the foaming agent and the grain groups of the granulate can comprise a mixing-in process or a foaming process or can be carried out exclusively by means of a mixing-in process or a foaming process. In the mixing process, the foam concrete mix is typically produced in a compulsory mixer with the addition of a foaming agent. In the foam process, a prefabricated foam is mixed into the binder and the grain groups, for example on the construction site or in a concrete plant.

In embodiments, the foam is generated with the aid of a foaming device such as a foam generator and a foaming agent. Typically, all components except for the foaming agent, for example binding agent, grain groups of the granulate and added water, are premixed and Last of all, the prefabricated foam or foaming agent was added. In further embodiments, the foam is generated and added to the binding agent or a mixture of binding agent and added water, with the addition of, for example, the grain groups only then.

In further embodiments of the invention, the foam concrete mix can be provided and mixed with fibers. The deformation behavior of foam concrete can be influenced with fibers. In embodiments, fibers can produce the effect of improved tensile strength. Typically, the term “fibers” includes at least one of the following fibers: vegetable fibers, plastic fibers, glass fibers, carbon fibers and steel fibers. The fibers, in particular plastic fibers, can, for example, have a minimum length of 1 mm, 5 mm, 10 mm, or 30 mm. The fibers, in particular plastic fibers, typically have a maximum length of 80 mm, 90 mm, and 120 mm.

Glass fibers with a minimum length of 0.5 mm, 1 mm, or 3 mm and / or with a maximum length of 60 mm, 80 mm, 100 mm or a maximum of 120 mm are typically used. Typically, the fibers comprise monocomponent fibers or bicomponent fibers or a mixture thereof or consist of one of these fibers or a mixture thereof. In embodiments, the fibers are used as fiber bundles or individual fibers. The foam concrete mixture typically contains less than 100 kg of fibers based on 1 m ^{3 of} the foam concrete mixture, typically less than 50 kg of fibers based on 1 m ^{3 of} the foam concrete mixture, in particular less than 20 kg of fibers based on 1 m ^{3 of} the foam concrete mixture or typically less than 5 kg Fibers based on 1 m ^{3 of} the foam concrete mixture. In particular, Concrix ^® , Dramix 2D or Dramix 3D, 4D or 5D are used as fibers - exclusively or in a mixture with other fibers.

A typical highly deformable foam concrete or a typical highly deformable foam concrete product is made with one of the foam concrete mixes described herein. In particular, the typical highly deformable foam concrete products described herein are used underground. In particular, the typical highly deformable foam concrete products described herein will be used in tunnel construction or mining or in a protective structure. For this purpose, highly deformable foam concrete products can be bar-shaped or plate-shaped compression elements or tubbing elements. For example, the bar-shaped or plate-shaped compression elements or tubbing elements can be used in compressive or swellable mountains.

Typical advantages of embodiments according to the invention are high deformability with comparatively low forces, so that rock movements underground can be absorbed without complete failure of the shell constructed with the embodiments. This offers a wide range of uses, particularly in tunnel construction or underground structures.

Figure list

• 1 zeigt schematisch einen Ablauf einer typischen Ausführungsform eines erfindungsgemäßen Verfahrens;
• 2 zeigt schematisch einen weiteren Ablauf einer typischen Ausführungsform eines erfindungsgemäßen Verfahrens;
• 3 zeigt schematisch die Ergebnisse von einachsigen Spannungsversuchen an Würfeln aus unterschiedlichen Schaumbetonmischungen;
• 4 zeigt schematisch die Ergebnisse von dreidimensionalen Spannungsversuchen an Würfeln aus unterschiedlichen Schaumbetonmischungen.

The invention is explained in more detail below with reference to the accompanying drawings, the figures showing:

• 1 shows schematically a sequence of a typical embodiment of a method according to the invention;
• 2 shows schematically a further sequence of a typical embodiment of a method according to the invention;
• 3 shows schematically the results of uniaxial tension tests on cubes made of different foam concrete mixes;
• 4th shows schematically the results of three-dimensional tension tests on cubes made of different foam concrete mixes.

Description of exemplary embodiments

Typical embodiments of the invention are described below with reference to the figures, the invention not being restricted to the exemplary embodiments, rather the scope of the invention is determined by the claims. In the description of the embodiment, the same reference symbols may be used for the same or similar parts in different figures and for different embodiments in order to make the description clearer. However, this does not mean that corresponding parts of the invention are limited to the variants shown in the embodiments.

In the 1 is a schematic overview of a sequence 100 of a typical method of making a foam concrete mix for the manufacture of highly deformable foam concrete products.

The method includes establishing a required minimum compressive strength 110 , a stipulation of a required minimum deformability 120 , a determination as a function of the required minimum compressive strength and the required minimum deformability percentage of at least the following substances: binders, foaming agents and grain groups of the granulate according to a grading curve 130 , and providing and mixing the determined percentages of at least the binder, the foaming agent and the grain groups of the granulate as a foam concrete mixture 140 .

Im in the 1 The exemplary embodiment shown comprises determining, depending on the required minimum compressive strength and the required minimum deformability, percentage proportions of at least the following substances: binders, foaming agents and grain groups of the granulate according to a grading curve 130 those in the overarching block 130 comprised blocks 132 - 139 . Determining the percentage of the binder, the foaming agent and the grain groups of the granulate according to a grading curve is typically done iteratively in the blocks 132 to 138 carried out.

In the block 132 Depending on the required minimum compressive strength and the required minimum deformability, percentage proportions of the grain groups of the granulate are determined or estimated according to a grading curve. Typically, several grain groups of the granulate are selected, for example in order to achieve a dense grain structure.

For example, in a first calculation, percentages of the grain groups of the granulate are calculated or estimated by means of a weighted, in particular volume-weighted average of the compressive strengths of the percentages of selected grain groups of the granulate. Furthermore, the corresponding percentage of the binder and possibly also of the foaming agent (compressive strength of the cavities created with the foaming agent equal to zero) can be determined in order to estimate or determine the total compressive strength of the later foamed concrete product (blocks 134 and 136 ).

In the block 138 It is checked whether the percentage of at least the following substances: binder, volume of the foam foamed by means of the foaming agent and grain groups of the granulate according to a grading curve, result in the required minimum compressive strength and the required minimum deformability. If this check is positive, the block 140 proceeded. If the check ends negative, the method continues with the block 139 to execute an iterative loop.

In the block 139 an estimation and adjustment of at least a portion of the percentage proportions takes place: binders, foaming agents and grain groups of the granulate according to a grading curve. For example, if the desired minimum compressive strength is not reached, a different binder can be used, fewer foaming agents can be used or other grain groups can be selected. If the minimum deformability is not achieved, for example the proportion of foaming agent and thus the voids created by the foaming agent can be increased. The process then jumps to the block 132 back.

In the block 140 take place after a positive outcome of the check in the block 138 providing and mixing the determined percentages of at least the binder, the foaming agent and the grain groups of the granules as a foam concrete mixture.

In the 2 is a schematic overview of a typical process for providing and mixing the percentages of the following substances: binders, foaming agents and grain groups of the granulate according to a grading curve and for producing a foam concrete mixture for the production of highly deformable foam concrete products 200 shown.

In a first mixer 210 uses cement as a binder 212 with grain groups of the granulate according to a grading curve 214 mixed. This is done with added water 220 in the first mixer 210 mixed to cement paste. The binder 212 is typically up to a W / C value of a maximum of 0.6, typically a maximum of 0.55, typically a maximum of 0.50, in particular a maximum or approximately 0.47 with added water 220 premixed. One or more additives are optionally added to the cement paste 216 such as concrete liquefier or setting accelerator added. Furthermore, one or more additives are optionally added to the mixture 218 added, which affects the workability of the fresh or the strength of the hardened concrete can influence. In contrast to the additives 216 they are taken into account in the material space calculation in typical exemplary embodiments.

It also becomes water 222 typically in a foam generator 230 with a foaming agent 232 and air 234 or at least one other gas, e.g. nitrogen, mixed to form a foam. For example, the foaming agent is mixed with the water for foaming in a storage tank of a foam generator. The foam produced is typically weighed. The foam density is typically checked. The foam generator 230 preferably works at an operating pressure of 4 bar maximum. In typical embodiments, additives can optionally be added to the cement paste or the foaming agent.

In typical embodiments, the water mixed with the foaming agent can be taken from the added water or all of the added water is mixed with the binder and an additional amount of water is provided for the foaming agent to be mixed with the foaming agent. Typically, the amounts of water required for foam formation are small, so that they do not necessarily have to be taken into account when calculating the mixture.

In a second mixer 240 is the cement paste from the first mixer 210 with the one in the foam generator 230 formed foam mixed and formed a flowable and pumpable foam concrete mixture. A foam concrete mix can also be made by mixing in the foam generator 230 foam formed in the first mixer 210 be formed with a cement paste.

From the second mixer 240 comes with a feed pump 250 or a means of transport for pouring out the foam concrete mixture at the place of use or applied in a casting mold in which it can set and a highly deformable foam concrete product 260 can generate.

The method according to the invention is further explained in more detail using the following exemplary embodiments:

Embodiment 1

For example, a cubic meter of a typical foam concrete mix for the manufacture of typical highly deformable foam concrete products may consist of or include: Poraver 0.5-1 mm 44.97 kg Poraver 1-2 mm 45.95 kg Poraver 2-4 mm 55.90 kg Poraver 4-6 mm 69.97 kg Foaming agent (total mass with water for foaming) 10.67 kg of which: foaming agent (Sika Lightcrete 400) 0.27 kg Binder (cement) 245.96 kg Added water 103.30 kg Plastic fibers (Concrix) 3.00 kg

In the exemplary embodiment, the water for mixing with the foaming agent is not taken from the added water. Specifically, 10.67 kg of foam are used per cubic meter of foam concrete mixture in the exemplary embodiment. The foaming agent Sika Lightcrete 400 is premixed with water. The 10.67 kg of foam contain 0.27 kg of Sika Lightcrete foaming agent 400 (corresponds to about a 2.5-3% solution of Sika Lightcrete 400 in water). The foaming agent is mixed with the water for foaming (here: 10.67 kg - 0.27 kg = 10.40 kg of water for foaming) in a storage tank of a foam generator and then the foam produced is weighed and the foam density produced is checked. By checking the foam density, it can be achieved that the required voids are also present in the foam concrete mixture according to the calculation. Sika Lightcrete 400 is available from Sika Schweiz AG, Tueffenwies 16 , CH 8048 Zurich.

The percentage of the grain groups in the granulate according to a Funk-Dinger grading curve.

A cubic meter of a comparable example with the same glue density as the glue density of the foam concrete mixture of embodiment 1 comprises or consists of: Foaming agent (total mass with water for foaming) 10.67 kg of which: foaming agent (Sika Lightcrete 400) 0.27 kg Binder (cement) 683.40 kg Added water 287.00 kg Plastic fibers (Concrix) 3.00 kg

In the 3 and 4th the results of the corresponding uniaxial and three-dimensional printing tests on cubes are shown in a schematic overview. The cubes are made from foam concrete mixes with grain groups of the granulate according to a grading curve and from foam concrete mix without grain groups. The foam concrete mixes are made with identical glue density values.

In 3 and 4th it can be clearly seen that a typical highly deformable foam concrete product 310 after overcoming the elastic deformation area, a smaller ratio between the minimum compressive strength and the stress in the plastic area of the highly deformable foam concrete product 310 as a corresponding typical foam concrete product 320 shows which, however, was produced without grain groups of the granulate according to a grading curve.

For example, the results of the uniaxial compression test in 3 for a highly deformable foam concrete product 310 according to the invention, a minimum compressive strength with a value of 0.9 MPa and a uniaxial stress with a value of 2.7 MPa with a deformability of 60%. In comparison, the results show for a typical foam concrete product 320 without granules in the 3 a minimum compressive strength with a value of 3 MPa and a uniaxial stress with a value of 12 MPa with a deformability of 60%. Thus, for a deformability of 60%, the ratio between the minimum compressive strength and the uniaxial stress is 3 in the case of a highly deformable foam concrete product 310 with typical grain groups. The corresponding value is 4 for a typical foam concrete product 320 without typical grain groups of the granulate according to a grading curve.

Furthermore, the results of the three-dimensional printing test in 4th for a typical highly deformable foam concrete product 410 a minimum compressive strength with a value of 1.5 MPa and a stress between 1.5 MPa and 4.0 MPa in the area of deformation between 0% and 40%. This is the ratio between the minimum compressive strength and the stress in the plastic range of the highly deformable foam concrete product 410 between 1.0 and 2.7 with 2.7 at 40% deformation.

In comparison, shows a typical foam concrete product 420 Without typical grain groups of the granulate according to a grading curve in the three-dimensional compression test, a minimum compressive strength of 4 MPa and a stress between 4 MPa and 13.5 MPa in the area of deformation between 0% and 40% ( 4th ). This is the ratio between the minimum compressive strength and the stress in the plastic range of the foam concrete product 420 between 1.0 and 3.4 with 3.4 with 40% deformation.

The ratio of the maximum stress to the minimum stress is in the range of up to 40% deformation in typical highly deformable foam concrete products 410 lower in the three-dimensional printing test.

List of reference symbols

210

first mixer

212

binder

214

Grain groups of the granulate according to a grading curve

216.236

Additives

220

Added water

230

Foam generator

232

Foaming agent

234

air

240

second mixer

250

Feed pump

260, 310, 410

highly deformable foam concrete product

320, 420

typical foam concrete product

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Non-patent literature cited

• DIN EN 12390-3 [0009, 0010, 0015, 0016]
• DIN EN 206-1 [0014]
• DIN 1045-2 [0014]
• DIN EN 197-1 [0022]
• DIN EN 14216 [0022]
• DIN EN 13055-1 [0037]

Claims (17)

Method for producing a foam concrete mixture for the production of highly deformable foam concrete products (260, 310, 410) with providing a foam concrete mixture comprising binding agent (212), foaming agent (232) and granulate, with: - Establishing a required minimum compressive strength (110); - Establishing a required minimum deformability (120); - Determine (130) depending on the required minimum compressive strength and the required minimum deformability percentage of at least the following substances: ◯ binders (212), ◯ Foaming agent (232) and ◯ Grain groups of the granulate according to a grading curve (214), and - Provision and mixing of the determined percentages of at least the binder (212), the foaming agent (232) and the grain groups of the granulate according to a grading curve (214) as a foam concrete mixture (140). Procedure according to Claim 1 , the percentages of the grain groups of the granulate being determined according to a grading curve (214) using a grading curve which deviates from a Fuller grading curve. Procedure according to Claim 1 or 2 , wherein the grading curve has a reduced proportion of small grain sizes compared to a Fuller grading curve. Method according to one of the preceding claims, wherein the foam concrete mixture contains at least 10 g and / or a maximum of 3 kg of the foaming agent (232) based on 1 m ³ of the foam concrete mixture. Method according to one of the preceding claims, wherein the granulate comprises foam glass granulate. Method according to one of the preceding claims, wherein the granulate consists of at least 50% spherical grains which have a grain shape with a diameter ratio of the largest to the smallest average diameter of less than 3: 1. A method according to any one of the preceding claims, wherein the foam concrete mixture is provided and mixed with fibers. Method according to one of the preceding claims, wherein the fibers comprise at least one of the following fibers: vegetable fibers, plastic fibers, glass fibers, carbon fibers and steel fibers. Method according to one of the preceding claims, wherein the foam concrete mixture contains less than 100 kg of fibers based on 1 m ^{3 of} the foam concrete mixture. Method according to one of the preceding claims, wherein the grain groups of the granulate according to a grading curve at least one of the grain groups with the limiting sieve (d _min / d _max ) 0.25 / 0.5 mm, 0.5 / 1 mm, 1/2 mm, 2/4 mm, 4/6 mm, and 4/8 mm. Method according to one of the preceding claims, with determining the percentages of the grain groups of the granulate according to a grading curve as a function of the required minimum compressive strength and the required minimum deformability (132) by selecting grain groups with a certain grain group compressive strength and / or a certain size range to achieve the required minimum compressive strength and the required minimum deformability in a foam concrete made with the mixture. Method according to one of the preceding claims, wherein the determination is carried out iteratively. Method according to one of the preceding claims, wherein the foam concrete mixture comprises so much added water (220), foaming agent (232) and binding agent (212) that the grain groups of the granulate form a dense grain structure according to a grading curve (214). Highly deformable foam concrete product (260, 310, 410), in particular intended for use underground, produced with a foam concrete mixture which is produced using a method according to one of the Claims 1 to 13 is made. Highly deformable foam concrete product (260, 310, 410) according to Claim 14 , the highly deformable foam concrete product (260, 310, 410) showing a corresponding compressive stress of less than 350% of the minimum compressive strength at 60% deformation. Use of a highly deformable foam concrete product (260, 310, 410) according to Claim 14 or 15th in tunnel construction or mining or in a protective structure. Use after Claim 16 , wherein the highly deformable foam concrete product (260, 310, 410) is a bar-shaped or plate-shaped compression element or a tubbing element.

Images