DE102017119096A1 - Wood-concrete ceiling - Google Patents

Abstract

The invention relates to a wood-concrete composite ceiling comprising a high-performance aerosol concrete, to processes for producing these wood-concrete composite ceilings, and to the use of high-performance aerobic concrete in wood-concrete composite ceilings.

Description

The invention relates to a wood-concrete composite ceiling comprising a high-performance aerosol concrete, to processes for producing these wood-concrete composite ceilings, and to the use of high-performance aerobic concrete in wood-concrete composite ceilings.

The upgrading and renovation of the building stock is becoming more and more important. For several years, a shift in emphasis has been observed in the construction industry, away from new construction, to building in existing buildings. This often presents the problem that existing wooden beam ceilings are to be trained in terms of carrying capacity, usability, building physics or fire protection.

The conversion of buildings often leads to higher payloads that can not be accommodated by the existing design. Moreover, beamed ceilings often have sags that make it impossible to use today's usability requirements. The air and impact sound insulation of wooden beamed ceilings is also well below the level required today. The vibration behavior of the relatively light ceilings still does not meet today's requirements.

A particularly great problem is the inadequate fire protection of wooden beam ceilings. More recently, the production of so-called wood composite ceilings has been established as a viable solution to this problem. In the process, a foil is laid on the existing wooden beamed ceilings onto which a reinforced concrete slab, which is usually 60 to 140 millimeters thick, is installed. The shear bond between wooden beams and reinforced concrete slab is ensured by composite elements such as composite screws, grooved in expanded metal or corrugated sheets or the like. The resulting hybrid cross-section increases both load-bearing capacity and serviceability. The soundproofing is improved as well as the vibration behavior and fire protection.

For example, Meyer (Meyer, Bruno, "Reinforcement of old beamed ceilings with lightweight concrete", Cement Bulletin 1990, 58, No. 10) describes the reinforcement of old beamed ceilings with lightweight concrete. Wooden beams and concrete are sheared together. In addition, composite materials such as wood screws, special screws or nails are used.

A composite ceiling made of wood and lightweight concrete with wood screws as connecting means is also proposed by the construction research project Fraunhofer IRB "Composite ceiling wood lightweight concrete" (1986 - 1988, project number 88008001351).

DE 197 02 238 A1 discloses the use of airgel particles, in particular in the form of composite materials for body and / or impact sound insulation.

Because of their positive properties, such ceiling constructions are increasingly also being used for new construction, in particular as prefabricated elements. However, when it comes to building in existing buildings, new problems arise when using wood-concrete composite floor coverings, which have so far remained unresolved. The sometimes considerable weight of the concrete slab consumes a large part of the increased load again. Load-bearing components such as beams, beams, walls or foundations thereby experience an additional burden, which requires additional reinforcements, or possibly even excludes the use of this construction.

The high thermal conductivity of reinforced concrete leads to a significant deterioration of the heat transfer coefficient of such ceilings, which requires additional measures such as the installation of thermal insulation, especially in cellar ceilings or top floors.

The present invention is therefore based on the object to provide wood-concrete composite ceilings with which the disadvantages of the prior art are avoided. In particular, wood-concrete composite ceilings are to be provided, which are characterized by a good ratio of thermal conductivity, load capacity and weight. At the same time, the soundproofing properties should be improved compared with the prior art, but in any case should not be worsened.

• 10 bis 85 Vol.-%/m³ Aerogelgranulat mit einer Korngröße im Bereich von 0,01 bis 4 mm,
• 100 bis 900 kg/m³ anorganisches hydraulisches Bindemittel,
• 10 bis 40 Gew.-% bezogen auf den Gehalt an Bindemittel wenigstens einer Kieselgel-Suspension,
• 1 bis 5 Gew.-% bezogen auf den Gehalt an Bindemittel wenigstens eines Fließmittels,
• 0,2 bis 1 Gew.-% bezogen auf den Gehalt an Bindemittelgehalt wenigstens eines Stabilisierers sowie
• 0 bis 60 Vol.-%/m³ wenigstens eines Leichtzuschlages, beispielsweise Leichtsande, Blähton und/oder Blähglas

enthält.In a first embodiment, this object is achieved by a wood-concrete composite floor comprising a high-performance aerosol concrete, wherein the high-performance aerated concrete is obtainable from a concrete mixture, the

• From 10 to 85% by volume / m ^{3 of} airgel granules having a particle size in the range from 0.01 to 4 mm,
• 100 to 900 kg / m ^{3 of} inorganic hydraulic binder,
• From 10 to 40% by weight, based on the content of binder of at least one silica gel suspension,
• 1 to 5 wt .-% based on the content of binder at least one superplasticizer,
• 0.2 to 1 wt .-% based on the content of binder content of at least one stabilizer and
• 0 to 60% by volume / m ^{3 of} at least one light aggregate, for example light sands, expanded clay and / or expanded glass

contains.

In particular, the concrete mixture may contain 10 to 75% by volume / m ^{3 of} the airgel granulate, 200 to 900 kg / m ^{3 of} the inorganic hydraulic binder, 20 to 40% by weight, based on the binder content of the at least one silica suspension, 2 to 5 % By weight, based on the content of binder of the at least one flow agent, and / or 10 to 60% by volume / m ^{3 of} the at least one lightweight aggregate.

The high-performance aerosol concrete contained in the wood-concrete composite floor is characterized by an extremely favorable ratio between bulk density and compressive strength, compressive strength and thermal conductivity as well as excellent soundproofing properties. Moreover, it is completely inorganic and thus non-flammable and non-toxic or carcinogenic. The high-performance aerosol concrete has only about 30 to 50% of the raw density of reinforced concrete and thus also allows the use of wood-concrete composite ceilings in weight-sensitive areas. Since the sound and fire protection properties far exceed those of normal concrete, the reinforced concrete slabs can be made thinner in the use of high performance aerated concrete in the wood-concrete composite slabs of the invention than corresponding reinforced concrete slabs in wood-concrete composite slabs from the prior art, which is another Weight reduction results. The thermal conductivity is compared to normal concrete only about one-tenth, so that by the use of high-performance aerosol concrete without further measures at the same time also carried out an energetic renovation.

In addition, the excellent sound insulating properties of the high performance aerosol concrete over the prior art to improve the soundproofing properties.

The wood-concrete composite floor comprises high-performance aerosol concrete, which is available based on the blend compositions for high performance concrete (HPC), ultra-high performance concrete (UHPC) and lightweight concrete (LC). The airgel concrete has extraordinary thermal insulation properties and comparable to normal concrete compressive strength. The outstanding thermal insulation properties are achieved by the use of airgel granules, in particular in an amount of 10% by volume to 75% by volume / m ³ , in particular 60 to 65% by volume / m ³ . The grain size of the airgel is 0.01 to 4 mm, in particular 1 to 4 mm. This grain size can be obtained by simple sieving. This fine particles, especially dust are removed. The presence of these fines leads to a deterioration of the compressive strength values.

The hydraulic binder is preferably contained in a proportion of 500 to 550 kg / m ³ in the concrete mixture for the high performance aerosol concrete of the wood-concrete composite ceiling of the present invention. In a preferred embodiment, the hydraulic binder comprises cement, in particular Portland cement.

The silica gel suspension of the concrete mixture preferably comprises 1 to 60% by volume of active substance (solids content). The silica gel suspension particularly preferably comprises 50% by volume of active substance (solids content).

The concrete mixture preferably has a w / c of 0.20 to 0.60, more preferably a w / c of 0.28 to 0.35.

• • Portlandzement,
• • Mikrosilika (Staub und Suspension),
• • Verschiedene übliche Zuschläge,
• • Quarzsand,
• • Betonverflüssiger,
• • Stabilisierer,
• • Aerogelgranulat,
• • Wasser,
• • Leichtzuschläge (beispielsweise Leichtsande, Blähton, Blähglas).

The composition of the individual components of the airgel concrete takes place taking into account the known mixing compositions for HPC, UHPC and LC. The examined components are listed below:

• • Portland cement,
• Microsilica (dust and suspension),
• • various common surcharges,
• • quartz sand,
• • concrete liquefier,
• • stabilizer,
• Airgel granules,
• • Water,
• • Light surcharges (eg light sands, expanded clay, expanded glass).

The mixtures prepared and tested from these components are described below:

According to the invention, the influence of the components listed above was investigated. For this purpose, 25 mixtures (prismatic specimens) were prepared with the aim of increasing the compressive strength. The concentrations of the additives, the concrete liquefier, the microsilica and the Portland cement were varied. After that, the best mixtures were further optimized. Cube specimens with a side length of 15 cm were tested in accordance with German standardization (EN 12390-3: 2009-7 Testing hardened concrete - Part 3: Compressive strength of test specimens, Berlin: Beuth Verlag, 2009). The following description refers to these optimized mixtures M1 to M13 ,

Another important aspect for the development of the compressive strength of airgel concrete is the type of storage. Three different types of storage were considered during the tests: Dry storage at an ambient temperature of 20 ° C ± 2 ° C, mixed storage according to EN 12390-2 (EN 12390-2 Ber 1: 2012-02 Testing hardened concrete - Part 2: Making and Berlin, Beuth Verlag, 2012) for six days under water at a water temperature of 20 ° C ± 2 ° C and the following 12 days in air at an ambient temperature of 20 ° C ± 2 ° C. In Schachinger, I. Studies on high performance fine grain concrete. 38th DAfStb Research Colloquium. TU Munich; 2000 p. 55-66, positive effects of a heat treatment on the compressive strength of HPC are reported. Therefore, also 24-h sample cubes were heat-treated in a drying oven for 24 hours. All cubes were switched off at 24h in the concrete age before being stored under the three different storage conditions specified.

Three samples were required for each mixture and each type of storage. In addition, the compressive strength was determined as specified above in the concrete age of seven and 28 days. Therefore, a total of 18 specimens were prepared for each mixture.

In order to determine the influence of the heat treatment and the heat of hydration of the airgel concrete, the temperature during the hydration process was measured by a temperature sensor embedded in the core of the sample cube. For each mixture three temperature measurements were carried out according to the three types of storage ( 1 ). 1 shows the temperature curves for the mixture M10 , During the first few hours, a significant increase in core temperatures was observed. After five to eight hours, the maximum temperature was reached. The high core temperature resulted from the high cement content and the addition of silica fume (see also Held M. High-strength construction lightweight concrete. Concrete 1996; 7: 411-415 ). The three temperature curves do not decrease as much as they rise. Regardless of the maximum temperature, the core temperature was for the blends M1 to M13 after 26h between 20 ° C and 25 ° C. During this period the air or water temperature was kept between 20 ° C and 25 ° C. Therefore, it can be assumed that the hydration process was completed after 26 h.

The heat treatment of the sample cube is also in 1 shown. The drying oven had an ambient temperature between 84 ° C and 93 ° C. The core temperature of the concrete cubes reached a maximum of 80 ° C and depends mainly on the high cement content and the silica content. The influence of the selected heat treatment on the compressive strength is low.

The results of the compressive strength tests and the associated densities are listed in Table 1. Table 1: Compressive strengths (f _{cm, cube, 150} ) of the optimized mixtures after 28 days (7 days) mixture M8 M5 M7 M1 M10 M9 M6 M12 M2 M11 M3 M4 M13 Dry Bulk Density ρ [kg / m ³ ] 730 750 810 850 860 880 940 1010 1015 1050 1070 1130 1170 Dry storage: f _cm [MPa] 3.1 6.2 7.9 7.4 8.9 9.9 9.8 13.0 11.5 15.3 13.8 17.1 21.1 Heat treatment: f _cm [MPa] 3.0 6.6 7.2 7.8 10.0 9.5 9.2 12.0 12.7 16.3 12.8 12.7 23.6 Mixed storage: f _cm [MPa] 3.7 7.3 7.9 8.4 9.3 9.2 10.1 11.7 13.9 16.5 12.7 15.8 23.1 Mixed storage: f _{cm, 7 days} [MPa] 3.7 5.6 7.4 8.1 8.9 6.6 7.7 11.6 10.3 14.5 10.9 16.2 19.2

Most blends achieved the highest compressive strength on mixed storage. The early heat treatment did not lead to significantly higher compressive strengths. With regard to the compressive strengths after seven and 28 days, no clear trend could be observed.

Another important aspect that has been identified in the investigations is the relationship between bulk density and compressive strength. In 2 the compressive strength of the 13 mixtures with mixed storage is plotted as a function of the bulk density. For this purpose, a linear regression analysis was performed. The coefficient of determination was calculated to be 0.93, which shows a high correlation between bulk density and compressive strength. According to Gibson LJ, Ashby MF Cellular solids. Cambridge University Press. 2nd Edition. Cambridge; 1997; p. 213, the compressive strength of porous bodies can be calculated as a function of the bulk density. Here, the values of the Portland cement used were used for ρ ₀ and σ _cr ⁰ . $${\sigma }_{cr}=0.2\cdot {\mathrm{<figure-callout\; id="0"\; label="\sigma \; c\; r"\; filenames="DE102017119096A1\_0002.png,DE102017119096A1\_0003.png"\; state="\{\{state\}\}">\sigma \; </figure-callout>}}_{cr}^{}\cdot {\left(\rho /{\rho }_0\right)}^{\left(3/2\right)}$$

Taking into account the investigations on airgel concrete from ratchet (loc.cit.), The exponent 3/2 in this equation should be replaced by ¾. Both functions are in 2 shown. In the experimental studies of the Institute for Solid Construction (IfM), most optimized mixtures achieved higher compressive strengths than due to Eq. (1) according to Ratke (loc.cit.) And Gao et al. (loc.cit) was to be expected. 3 shows the compressive strength of 13 mixtures in a concrete age of 28 days in relation to the bulk density.

The thermal conductivity of some mixtures ( M5 . M8 to M13 ) was determined using the Transient Hot Bridge (THB) measurement method. The results of the IfM and Gao et al. (loc.cit) are in 3 shown. A correlation between compressive strength and thermal conductivity is clearly visible. In both investigations, the thermal conductivity increases with increasing compressive strength (and bulk density). The test results from Gao et al. (loc.cit.) are between 8 MPa and 62 MPa with associated thermal conductivities between 0.26 W / (m · K) and 1.9 W / (m · K), while the compressive strengths and thermal conductivities determined according to the invention between 6 MPa and 25 MPa or 0.17 W / (m · K) and 0.26 W / (m · K). That is, for the high-performance aerosol concrete of the wood-concrete composite slabs according to the invention, smaller values for the thermal conductivity and thus better thermal insulation properties were found at comparable compressive strengths. 3 shows the relationship between compressive strength and thermal conductivity.

On the basis of the known formulations for HPC, UHPC and LC wood composite concrete ceilings can be obtained according to the invention with an airgel concrete with a compressive strength increase while maintaining good thermal insulation properties.

The compressive strength correlated with the bulk density and reached values up to 25.0 MPa. With regard to the compressive strengths after seven and 28 days, no clear trend could be observed. The thermal conductivities were determined to be 0.16 ≦ λ ≦ 0.26 W / (m · K), which is to be equated with good thermal insulation properties. The best mixture achieved a compressive strength of 10 MPa with an associated bulk density of 860 kg / m ³ and a thermal conductivity of 0.17 W / (m · K).

According to the invention, the wood-concrete composite ceiling comprises composite elements made of wood and composite elements made of high-performance aerosol concrete. The composite elements of wood, for example, a include conventional wooden beamed ceiling. Such a beamed ceiling comprises wooden supporting elements in the form of sawn or hewn (ceiling) beams resting on the walls. The upper end may be a board floor made of boards attached across the beams. The high performance aerosol concrete may in a preferred embodiment rest on the plank sheet. It can also be laid, for example, a film between the plank floor and the layer of high-performance aerosol concrete. The layer of high performance aerosol concrete preferably has a thickness of 60 to 300 millimeters, in particular a thickness of 60 to 200 millimeters, most preferably of 140 millimeters. The high-performance aerosol concrete may also comprise a reinforcement, for example made of steel.

In an alternative embodiment, the wooden composite elements may also comprise wooden beams with which the airgel concrete is directly connected. On the plank floor in the form of wooden boards can be omitted, for example.

Preferably, the composite elements made of wood with the composite elements of airgel concrete are non-positively connected. The frictional connection can be achieved, for example, by means of composite means. Here, all conventional and known from the prior art composite means, in particular those which are suitable for conventional wood composite cover, can be used.

• 4 zeigt beispielhaft eine Verbindung der hölzernen Verbundelemente mit den Verbundelementen aus Aerogelbeton mithilfe von stiftförmigen Verbindungsmitteln, beispielsweise Spezialschrauben.
• 5 zeigt beispielhaft eine Verbindung der hölzernen Verbundelemente mit den Verbundelementen aus Aerogelbeton mithilfe von Lochblechen.
• 6 zeigt beispielhaft eine Draufsicht auf die Verbindung mit Lochblechen, die in 5 dargestellt ist.
• 7 zeigt beispielhaft eine Verbindung der Verbundelemente mithilfe von Nuten/Kerven.

The composite means may include, but are not limited to, dowels, screws, adhesives, grooved expanded, perforated or corrugated sheets, nails, and / or cervels 4 to 7 ).

• 4 shows by way of example a connection of the wooden composite elements with the composite elements of airgel concrete using pin-shaped connecting means, for example special screws.
• 5 shows an example of a compound of the wooden composite elements with the composite elements of aerated concrete using perforated plates.
• 6 shows by way of example a plan view of the connection with perforated plates, which in 5 is shown.
• 7 shows an example of a compound of the composite elements using grooves / cervels.

The composite means may be made of metallic materials and / or wood, for example. In an alternative embodiment composite anchors made of concrete, in particular of ultra-high performance concrete, can be used. The composite anchors made of concrete can be used in the previously described form. In particular, grooves or cements made of concrete can be used.

The high-performance airgel comprised in the wood-concrete composite slabs according to the invention can be produced, for example, using water using the mixture described above. It is of particular importance to first mix the solid at room temperature components together before the liquid at room temperature ingredients, especially water-solvent or water-silica mixture and optionally water, are added.

Particularly low w / c values and associated high compressive strengths are obtained by cooling the addition water before mixing with the solid components, in particular to a temperature of less than 10 ° C, more preferably to less than 5 ° C.

Silica gel suspensions in the context of the present invention are commercially available and in particular comprise a highly reactive, high specific surface area, amorphous microsilica-water mixture, for example MC Centrilit Fume SX: Blaine value 20000, ie 4 to 5 times greater than cement / Binder. Mixing ratio 1: 1 (by volume).

Flow agents in the context of the present invention are commercially available and include in particular commercially available polycarboxylates, for example Powerflow 3100: polycarboxylate ethers having 30 wt.% Solids content, high charge density and short side chains.

Stabilizers according to the present invention are commercially available and include in particular commercially available organic polymers, for example MC Stabi 520, water-absorbent and water-storing cellulose.

In addition to the above components of the airgel concrete mixture, the mixtures may also contain other conventional concrete admixtures and concrete admixtures.

• „Ein Stoff, der während des Mischvorgangs des Betons in einer Menge hinzugefügt wird, die einen Masseanteil von 5 % des Zementanteils im Beton nicht übersteigt, um die Eigenschaften der Betonmischung im frischen/ und/oder erhärteten Zustand zu verändern.“

Concrete admixtures are defined in European Standards EN 934 "Additives for concrete, mortar and grout", which are mandatory in all CEN member countries. Part 2 of EN 934 contains the definitions and requirements for concrete admixtures:

• "A substance which is added during the mixing process of the concrete in an amount not exceeding 5% by mass of cement in the concrete in order to change the properties of the concrete mixture in the fresh / and / or hardened state."

• • Betonverflüssiger,
• • Fließmittel,
• • Stabilisierer,
• • Luftporenbildner,
• • Beschleuniger: Erstarrungsbeschleuniger und Erhärtungsbeschleuniger,
• • Verzögerer und
• • Dichtungsmittel.

EN 934-2 contains definitions and requirements for the following individual action groups:

• • concrete liquefier,
• • flow agent,
• • stabilizer,
• • air entraining agents,
• • accelerator: solidification accelerator and hardening accelerator,
• • Retarder and
• • sealant.

Sand (ρ ≥ 1400 kg / m ³ ) is generally not required because it is replaced by airgel granules.

The load-bearing capacity and the thermal conductivity of the wood-concrete composite slabs according to the invention comprising high-performance aerosol concrete can be further optimized by using the building material high-performance aerosol concrete graded or graded.

Airgel concretes dry within a few days and show only a low water absorption capacity after hardening. Aerogels are non-toxic, not carcinogenic and have been classified by the Federal Environmental Agency of the Federal Republic of Germany as "largely harmless material". Airgel concrete is an excellent fire protection material and has a high sound absorption.

The wood-concrete composite ceiling according to the invention thus also has the advantage that it retards the spread of fire stronger than wood-concrete composite ceilings from the prior art. Thus, the high-performance aerosol concrete conducts the heat emitted by a fire source much worse than conventional reinforced concrete, thus increasing the time until the ignition of the wooden composite elements. A particularly advantageous fire behavior results when the composite elements made of wood are completely surrounded by the composite elements of high-performance aerosol concrete.

In the wood-concrete composite ceilings according to the invention, the rebar reinforcement used hitherto also be replaced for example by a reinforcement made of glass fiber reinforced plastic. This reinforcement is commercially available, but so far used only in normal or conventional lightweight concrete. Investigations of the composite behavior between high-performance aerobic concrete and GRP reinforcement have shown that the bond stresses of up to f _b = 3 MPa are considerably higher than those previously determined for aerogra- phic concrete with reinforcing steel reinforcement and, moreover, in the value range of conventional reinforced concrete. The high-performance aerosol concrete contained in the wood-concrete composite slabs according to the invention thus enables the production of GFRP-reinforced airgel concrete components. Moreover, GRP reinforcement with a coefficient of thermal expansion of 6 × 10 ^-6 1 / K is much better suited for use in aerated concrete than reinforcing steel. Since airgel concrete components are used almost exclusively in areas where high demands are placed on heat insulation, the use of GRP reinforcement also proves particularly advantageous in this respect: the thermal conductivity of GFRP is 0.7 W / (m · K ) by a factor of 85 under the thermal conductivity of reinforcing steel. Since GRP reinforcement, unlike rebars, makes no demands on an alkaline environment, smaller concrete coverages and thus better cross-sectional utilization are possible.

The high-performance aerosol concrete has a much better ratio between compressive strength and thermal conductivity (λ ≦ 0.26 W / (m · K) at an average compressive strength of f _c = 25 MPa).

In a further embodiment, the object of the invention is achieved by a method for producing a wood-concrete composite floor, wherein the airgel concrete mixture on the wooden ceiling is poured on site, the concrete is connected to the timber ceiling frictionally, optionally composite material are introduced and the concrete is then cured. Preferably, the concrete mixture is prepared by first mixing all solid at room temperature ingredients before the liquid at room temperature ingredients, in particular water-flow agent or water-silica mixture and optionally water, are added.

In a preferred embodiment of the method according to the invention, in the preparation of the airgel concrete mixture, the addition water is cooled before mixing to a temperature of less than 10 ° C., more preferably to a temperature of less than 5 °.

In a further embodiment, the object according to the invention is achieved by the use of a high-performance aerosol concrete as a composite element in a wood-concrete composite floor.

• 10 bis 85 Vol.-%/m³ Aerogelgranulat mit einer Korngröße im Bereich von 0,01 bis 4 mm,
• 100 bis 900 kg/m³ anorganisches hydraulisches Bindemittel,
• 10 bis 40 Gew.-% bezogen auf den Gehalt an Bindemittel wenigstens einer Kieselgel-Suspension,
• 1 bis 5 Gew.-% bezogen auf den Gehalt an Bindemittel wenigstens eines Fließmittels,
• 0,2 bis 1 Gew.-% bezogen auf den Gehalt an Bindemittel wenigstens eines Stabilisierers und
• 0 bis 60 Vol.-%/m³ wenigstens eines Leichtzuschlages,

enthält.Preferably, a high performance aerosol concrete is used which is obtainable from a concrete mix which

• From 10 to 85% by volume / m ^{3 of} airgel granules having a particle size in the range from 0.01 to 4 mm,
• 100 to 900 kg / m ^{3 of} inorganic hydraulic binder,
• From 10 to 40% by weight, based on the content of binder of at least one silica gel suspension,
• 1 to 5 wt .-% based on the content of binder at least one superplasticizer,
• 0.2 to 1 wt .-% based on the content of binder at least one stabilizer and
• 0 to 60% by volume / m ^{3 of} at least one light aggregate,

contains.

The use of such a high performance aerosol concrete in a wood-concrete composite floor leads to the aforementioned advantages over the prior art wood-concrete composite ceilings.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 19702238 A1 [0007]

Cited non-patent literature

• Held M. High-strength construction lightweight concrete. Concrete 1996; 7: 411 to 415 [0024]

Claims (15)

A wood-concrete composite floor comprising a high performance aerosol concrete, said high performance aerated concrete being obtainable from a concrete mix containing 10 to 85% by volume / m ^{3 of} airgel granules having a particle size in the range of 0.01 to 4 mm, 100 to 900 kg / m ³ inorganic hydraulic binder, 10 to 40 wt .-% based on the content of binder at least one silica gel suspension, 1 to 5 wt .-% based on the content of binder at least one superplasticizer, 0.2 to 1 wt .-% relative on the content of binder at least one stabilizer and 0 to 60 vol .-% / m ^{3 of} at least one lightweight aggregate. Wood-concrete composite ceiling after Claim 1 , characterized in that the concrete mixture contains 60 to 65 vol.% of the airgel granules. Wood-concrete composite ceiling after Claim 1 or 2 , characterized in that the airgel granules have a particle size in the range of 1 to 4 mm. Wood-concrete composite ceiling after one of Claims 1 to 3 , characterized in that the concrete mixture comprises 500 to 550 kg / m ^{3 of} the inorganic hydraulic binder. Wood-concrete composite ceiling after one of Claims 1 to 4 , characterized in that the inorganic hydraulic binder comprises cement, in particular Portland cement. Wood-concrete composite ceiling after one of Claims 1 to 5 , characterized in that the silica gel suspension 1 to 60 vol .-%, in particular 50 vol .-% active substance (solids content). Wood-concrete composite ceiling after one of Claims 1 to 6 , characterized in that the concrete mixture has a w / c value of 0.20 to 0.60, in particular from 0.28 to 0.35. Wood-concrete composite ceiling after one of Claims 1 to 7 , characterized in that it comprises wooden beams and wooden boards placed crosswise to the wooden beams, the high-performance aerosol concrete resting on the wooden boards. Wood-concrete composite ceiling after one of Claims 1 to 7 , characterized in that it comprises wooden beams and the high-performance aerosol concrete is connected directly to the wooden beams. Wood-concrete composite ceiling after one of Claims 1 to 9 , characterized in that it comprises composite means which effect a frictional connection between wood and concrete. Method for producing a wood-concrete composite floor according to one of Claims 1 to 10 wherein the concrete mixture is poured onto the wooden ceiling on site, the concrete is non-positively connected to the wooden ceiling, optionally composite materials are introduced and the concrete is then cured. Method according to Claim 11 , characterized in that the concrete mixture is prepared by first mixing all solid at room temperature components before the liquid at room temperature ingredients, in particular water-flux or water-silica mixture and optionally water, are added. Method according to Claim 12 , characterized in that in the preparation of the concrete mixture, the addition of water before mixing to a temperature of less than 10 ° C, in particular to less than 5 ° C, cools. Use of a high-performance aerosol concrete as a composite element in wood-concrete composite ceilings. Use after Claim 14 characterized in that the high performance aerosol concrete is obtainable from a mixture comprising 10 to 85% by volume / m ^{3 of} airgel granules having a particle size in the range of 0.01 to 4 mm, 100 to 900 kg / m ^{3 of} inorganic hydraulic binder, 10 to 40 wt .-% based on the content of binder at least one silica gel suspension, 1 to 5 wt .-% based on the content of binder at least one superplasticizer, 0.2 to 1 wt .-% based on the content of Binder of at least one stabilizer and 0 to 60 vol .-% / m ^{3 of} at least one lightweight aggregate contains.

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