Wall construction made of stone slabs as a co 2 sink with fibres composed of biomass

Abstract

The invention relates to the construction of more or less thin fibre-stabilized house walls, the load-bearing slabs of which are stabilized such that they form an insulating intermediate layer for reinforcement across the cross section, wherein the intermediate layer contains pure carbon which is preferably derived from atmospheric CO2, and the stabilizing fibres are derived from carbon fibres made from lignin or flax fibres and are preferably applied in part to the outer side of the stone slabs.

Description

[0001] Wall construction made of stone slabs as a COg sink with fibers from biomass

[0002] The present invention relates to a wall construction as already described in EP08874021.2. This wall construction has a symmetrical structure composed of pressure-resistant panels held at a specific distance. The insulating layer, which stiffens the construction across its cross-section, is located between the panels. The two panels absorb the compressive forces and are made of particularly pressure-resistant materials such as natural stone, all types of artificial stone, concrete, and other earthenware, as well as ceramics, glass-containing substances, or glass—hereinafter referred to as earthenware—which, while pressure-resistant, are generally also characterized by a brittle and fragile structure.Particularly suitable here are natural stones such as granite, granite-like rocks such as gneiss, as well as marble, limestone, high-pressure-resistant modern ceramics, glass ceramics, or glass, as well as all other materials made of stone or ceramic, naturally or artificially formed earthenware. The two panels can be made of the same material or different materials, for example, the outer stone panel made of natural stone and the inner stone panel made of concrete.

[0003] These materials are characterized by high compressive strength combined with a comparatively low specific gravity. However, they are also relatively unstable under tensile and flexural loads, especially when they are designed to be as thin as possible, save material, and, above all, be as lightweight as possible. An additional goal of this invention is to bind as much carbon as possible in the insulation material, which stiffens the overall structure, in order to make the building material CO2-negative overall.

[0004] This is primarily highly porous coal, either plant-based or synthetically produced, which is incorporated into the insulation layer. This coal serves the purpose of providing good thermal insulation, reducing the weight of the insulation layer, and storing carbon in a highly concentrated form.

[0005] The present invention proposes a method for sustainably and inexpensively stabilizing such thin stone or earthenware slabs, or ceramic or artificial stone slabs, and for additionally serving as carbon sinks, using the method proposed here to create a self-supporting wall element. The stone, ceramic, or glass, and other pressure-resistant materials such as thin concrete slabs—generally referred to here as earthenware—which previously represented additional weight for building construction purely as facade cladding, now become the load-bearing element of the house wall itself. The insulation layer, together with the carbon fiber, when made from organic oil, becomes an efficient carbon sink and, due to its high temperature resistance, is capable of setting concrete in the event of a fire.Gabbro rocks are dimensionally stable up to 1050°C. They lose compressive strength, but even in the form of slender slabs, they remain capable of absorbing compressive loads if the wall is weakened by fire loads. Conventional structural concrete, when thin slabs are used, is unable to withstand such high fire loads without losing all load-bearing capacity. This is important for future lightweight construction potential in the building sector.

[0006] It is important that such wall elements remain dimensionally stable across a wide temperature range and that the "bimetallic effect" is suppressed. To achieve this goal, it is not only necessary to stabilize the earthenware or ceramic tiles against tension and the associated fractures, but also to establish an expansion distribution on the stone side to be stabilized at the interface between the stone to be stabilized and the insulation layer, the gradient of which approaches virtually zero. This ensures that the stone slab does not bend to one side or the other, even under fluctuating temperatures, and thus the visible surface remains largely straight and flat, rather than dished.

[0007] For this, it is important that the insulating intermediate layer is porous enough that the fiber material is able to accommodate the expansion of all components without the boundary layers separating from each other. The invention proposes such an approach with a symmetrical wall structure, whereby the feature of the flatness of the stone slab over wide temperature and pressure ranges becomes an essential core of the invention, in combination with a second characteristic feature of using the facade element itself as a load-bearing component: a tensile-stable fiber layer, preferably made of plant-based carbon or, alternatively, of low-energy fibers such as glass fibers or stone fibers.

[0008] This method ensures that the earthenware is stabilized under a wide range of thermally induced mechanical loads, as well as purely mechanical loads, so that it is protected from mechanical destruction through cracking of the wall panel, on the one hand, and, in particular, from thermally induced bending, on the other hand, by a stabilization suitable for the respective application and load cases. Dimensional stability in the presence of temperature differences on the inside and outside of the wall, and also the resulting temperature changes on the weather-dependent side, is also of significant importance, which can also be supported by making the panels from different materials with different expansion coefficients.

[0009] The key to finding the most suitable insulation material for self-supporting sandwich-type walls is to keep the overall expansion coefficient of the inner and outer panels as low as possible and, in particular, as equal as possible, to allow for carbon absorption, ensure good fire protection, and possess high insulation values, as well as be dimensionally stable, waterproof, and frost-resistant. Promising candidates for bonding the individual elements of such a wall are mineral adhesives, which possess sufficient flexibility and tensile strength to prevent buckling when bonded to the fiber-stabilized earthenware panels and to transfer loads.

[0010] The optimal statics are achieved by the fact that such a natural stone slab, for example, made of gabbro, has twice the load-bearing capacity of a comparable concrete slab of the same weight. This enables lighter, taller, and more spacious construction compared to traditional concrete and brick construction. Weight and space are also saved compared to steel construction because, for example, granite, with a specific weight of aluminum, is 2.7 times lighter than steel, yet has a compressive strength very close to that of structural steel.

[0011] The following is a structural description of the wall construction. The invention filed for application relates to the construction sector, in particular to building construction, more specifically to residential buildings, including service buildings, residential buildings, pavilions, halls, and any type of building in general. The core of the invention concerns a novel technique for constructing a house wall as a building element, with the functions of static load transfer and a facade with all the functions of a building envelope and the corresponding physical requirements according to current standards.

[0012] The wall elements are prefabricated and installed on site. The ceiling structures are placed on top of the wall elements. The wall elements combine all static and building physics requirements in a sandwich structure. The outer thin panes made of earthenware or other pressure-resistant materials primarily absorb the normal forces (pane forces). They can be used directly as finished, visible surfaces both indoors and outdoors. The core of the sandwich consists, for example, of a shear-resistant, thermally insulating foam that is rigidly connected to the outer panes. The core absorbs the shear forces from bending stresses, resulting in sufficient flexural rigidity perpendicular to the element. The element is thus protected against buckling and can absorb horizontal loads occurring perpendicular to the element, such as wind loads.The load transfer and load transfer structure, made of well-insulating stone, from the floor slabs to this sandwich element, transfers the vertical loads symmetrically to the panels without creating a thermal bridge that would be unacceptable from a structural point of view. Watertightness and vapor tightness are ensured by the interaction of the sandwich materials with special connection details. The load level without additional structural structures is >= 75 kN / m. The elements are installed as pendulum supports in the slabs at the top and bottom, using structural principles. The thermal insulation values ​​can achieve the Swiss Minergie standard.

[0013] The thin panels are made of a compressive and shear-resistant, waterproof material such as concrete, natural stone, glass, or ceramic. They are secured by reinforcement against tensile stresses from thermally asymmetric deformations and against tensile stresses in the stress distribution area of ​​the load introduction zones, which could lead to unannounced total brittle fractures. Imperfections in the material and structure can also be bridged, creating a benign, ductile material behavior. The sandwich core consists of a shear-resistant, highly thermally insulating structure, usually made of a sufficiently strong foam.

[0014] The load introduction consists of a thermally weakly conductive, compression- and shear-resistant element made of stone or wood or a combination of stone and wood, which is force-fitted to the stone discs with mineral adhesive material or dovetail galvanization or both.

[0015] The connections between the panes and the load introduction, the panes and the stiffening ribs, are created using permanent, shear-resistant bonds. Commercially available mineral adhesives, such as high-temperature water glass with a temperature resistance of at least 600°C, are used. Carbon materials made from CO2 are used as insulating layers.

[0016] To stabilize the stone slabs themselves, the use of fiber materials with a mineral matrix is ​​proposed, such as carbon fibers, preferably those made from biomass and, in turn, preferably from lignin or flax-based fibers, which stabilize the stone over a large area and prevent expansion and fracture. Natural stone itself has a very low expansion modulus, which can be adjusted with fiber stabilization, as natural stone is compressible due to its porous structure. If the fiber tension is sufficiently large and the correct fiber is used, or if the fiber can be used to introduce appropriate prestress into the composite of fiber matrix and stone, temperature-induced expansion of the stone slab is minimized.The invention described here relates to carbon fibers made from lignin or flax fibers, as these are cheaper than PAN fibers and also possess sufficient stiffness for the purpose described here, as in this case they are attached to the exterior of the stone slabs as tensile reinforcement. These fibers are ultimately all produced from CO2 and are bio-based.

[0017] Another innovation is the use of a fiber matrix on the outside of one or both load-bearing stone slabs to promote buckling of the flat slabs despite the relatively low stiffness of a lignin-based or flax-based fiber. For aesthetic reasons and also as a protective function of the matrix, this fiber layer can then be covered with a thin layer of stone. The result is a flat slab that can withstand compression and tensile stress, which in this application ensures sufficient stabilization of the stoneware against cracking and breakage. This makes this slab, in the symmetrical overall composite - fiber-stabilized stone slab, insulation cross-section - another fiber-stabilized stone slab - not only visually attractive both indoors and outdoors, but also represents a completely new type of wall construction that is about twice as light or even more with the same load-bearing capacity.can be kept thinner than conventional house walls and building structures.

[0018] The carrier material, hereinafter referred to as the "carrier," consists of a fiber-reinforced matrix based on water glass, as described, for example, in patent application EP 106 20 92. Carbon fibers, for example, are used, which can withstand high tensile loads and contract under the influence of heat. They therefore have a negative coefficient of thermal expansion and provide long-term stabilization for a more or less thin stone slab. This protects the slab, in particular, against cracks caused by overstretching and counteracts breakage caused by mechanical stress perpendicular to the stoneware. Depending on the application, such slabs must also be made statically stable (including against buckling forces) against mechanical stresses, as described in EP 106 20 92 with a sandwich insert. In this invention, this is achieved by a layer consisting of the insulation material solutions outlined above.

[0019] With the help of, for example, temperature-stable mineral water glass adhesives in combination with, for example, carbon fibers, which have a negative thermal expansion coefficient, such secure stabilization is possible even for very large stone slabs. Furthermore, the requirement to optimize the mechanical and thermal load-bearing capacity of thin stone structures is met so that the overall expansion coefficient of the slab is controlled over wide temperature ranges, thus preventing warping of the entire slab while still achieving a lightweight construction. To transfer the compressive forces that must be absorbed by such a house wall into the wall, the invention describes stiffening ribs that are bonded to the stone slabs using mineral adhesives. The bond can be improved by galvanizing.Wood can be particularly useful in construction for fire protection reasons, for example, for connecting internal or even external stiffening ribs that prevent walls from buckling. Wood is fire-resistant in the construction and can withstand even extreme temperatures when no air supply is available. In the case of external ribs, galvanizing techniques can be used not only to connect them to the stone slab, but also to connect the ribs to each other in a high-temperature-resistant manner to prevent the slabs from buckling in the event of a fire. The overall design of the innovative wall construction described here takes into account the fact that special vapor barriers are not necessary, as the stone is sufficiently waterproof, but its porosity ensures the necessary moisture permeability.The stone panels can absorb, transmit, and release a certain amount of water over extended periods, thus regulating the moisture balance between the interior and exterior spaces. If such walls are additionally designed to have a high carbon content in the insulation layer, this carbon not only improves the insulation properties and moisture regulation, reducing the expansion coefficient and the weight of the insulation layer, but also transforms the insulation layer's high volume relative to the load-bearing structure into an efficient carbon sink, enabling the achievement of climate targets through a building material adapted to the climate challenge itself. While previous building materials have caused CO2 emissions, this new building material concept is intended to reverse CO2 emissions and help recapture and rebind the CO2.

[0020] One of the many possible embodiments is shown in Fig. 1, the horizontal section through the wall. The wall is shown with two stone slabs (1) which are stabilized on the outside with a carbon fiber or flax fiber layer with a water glass matrix (2). An insulation layer (3) made of a fill of CC>2-based coal, which has a high carbon content, is inserted between the fiber-coated stone slabs. Figs. 2, 3 and 4 show the vertical sections through the wall at the points where the sufficiently compressive and tensile stable ribs (5) are located. These ribs are attached to the inside of the slabs and are force-fitted to one side of the stone slabs with mineral adhesive. The load introductions (4) at the top and bottom transfer the compressive forces into and out of the wall. Figs. 2 and 3 show points where the ribs are glued with galvanization, Fig.Figure 4 shows the wall with one internal and one external rib reinforcement at a location without galvanization. Figure 3 shows the rib reinforcements, which are connected to each other with a dovetail-shaped wooden wedge (6) to absorb the kick forces for as long as possible, even in the event of a fire. If necessary, the carbon fill can be mechanically supported by embedded rock wool fibers.

[0021] Fig. 5 shows the cross-section at a location where there is no bracing in the wall and where, in contrast to Figure 1, only one of the two stone slabs (1a) is stabilized on the outside with carbon fibers or flax fibers, or a mixture of such fibers, and the other stone slab (1b) is stabilized on the inside. Which of the two sides has the matrix fiber layer on the inside may depend, for example, on which stone slab is subjected to higher or longer-lasting temperature stress in the event of a fire. If the interior is subjected to higher temperature stress, it makes sense to coat the stone slab located in the interior with carbon on the inside.

Claims

Patent claims 1) Load-bearing wall element for buildings with two symmetrically arranged support plates made of stone, natural stone, artificial stone, ceramic, concrete, glass or glass-containing material, - whereby a cross-sectionally increasing, insulating layer of insulation material between both support plates stiffens the overall arrangement, - the carrier plates are stabilized with a fiber-containing matrix based on water glass, - the load-bearing wall element has a load introduction structure at the top and bottom, which is connected to the support panels via permanent shear-resistant adhesives, thus connecting them force-fittingly, - the cross-sectional increasing insulation layer consists of a bed of CO2-based carbon with high porosity - whereby the two carrier plates each consist of different or similar plate material, - and wherein the fiber material of the reinforcement consists of lignin-based carbon fibers or flax-based or flax fibers or a mixture of these fibers. 2) Load-bearing wall element according to claim 1, characterized in that the layer of stabilizing carbon fiber or flax fiber is arranged on the inside of at least one of the load-bearing stone slabs. 3) Load-bearing wall element according to claim 1 and 2, characterized in that the layer of carbon-based insulation material originates from atmospheric CO2. 4) Load-bearing wall element according to claims 1 to 3, characterized in that the layer of carbon-based insulation material is mechanically supported by means of rock wool. 5) Load-bearing wall element according to claims 1 to 4, characterized in that the support plates on the inner sides or the outer sides are each partially connected to the support plates with stiffening ribs made of stone at certain intervals with the aid of mineral adhesive, which are either attached only to each support plate individually or, in the case that all ribs are located on the inside, the support plates are attached in a force-fitting manner. 6) Load-bearing wall element according to claims 1 to 5, characterized in that the force-fitting connection of the ribs with the load-bearing plates is connected by means of galvanization. 7) Load-bearing wall element according to claims 1 to 6, characterized in that the force-fitting connection of the ribs to one another is made by means of a galvanization of wood. 8) Load-bearing wall element according to claims 1 to 7, characterized in that the supporting rock wool embeds the coal in one or more layers, wherein the layers of rock wool and layers of coal fill alternate.

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