CONSTRUCTION OF A WALL MADE WITH STONE SLABS AS A CO2 SINK WITH CARBON FIBERS FROM BIOMASS

Abstract

The invention describes the construction of relatively thin, fiber-stabilized house walls, in which the load-bearing panels are stabilized to form an insulating intermediate layer that stiffens the cross-section. This intermediate layer contains pure carbon in the form of biochar or charcoal, preferably derived from atmospheric CO2. The stabilizing fibers are biogenic carbon fibers applied to the interior or exterior of the stone panels. In combination with the weathering potential of the stone dust generated during production, the house wall becomes significantly CO2 negative.

Description

[0001] Wall construction made of stone slabs as a CO2 sink with carbon fibers from biomass

[0002] The present invention relates to an innovative wall construction that serves as a CO2 sink. This construction is based on the principles of EP08874021 and EP20702566, using a symmetrical arrangement of pressure-resistant panels. An insulating layer is located between these panels, which contributes to the rigidity of the structure. The panels are made of pressure-resistant materials such as natural stone, artificial stone, concrete, glaze, or ceramic, which, while pressure-resistant, are generally brittle and prone to breakage. This includes, in particular, natural stones such as granite, gneiss, marble, limestone, basalt, and gabbro, as well as concrete. These materials weather on their surfaces and absorb CO2 in the process.

[0003] The goal of this invention is to bind carbon in the insulation material to make the building material CO2-negative. Unlike previous patents, the insulation layer in this case consists of pure BioChar. BioChar is a form of coal produced by pyrolysis of biomass. In this thermochemical process, organic material is decomposed in the absence of oxygen at temperatures between 300 and 700 °C. BioChar, incorporated into the insulation layer, provides excellent thermal insulation and reduces the weight of the wall structure. It stores carbon in a highly concentrated form.

[0004] The wall consists of thin stone or ceramic panels, which are stabilized using an innovative method to make them self-supporting. This construction also serves as a highly efficient carbon sink. Materials such as gabbro retain their shape up to 1050°C and only minimally lose their compressive strength, which is particularly important for lightweight structures in the event of a fire. The construction ensures that the stone panels remain dimensionally stable and do not collapse even during temperature fluctuations. Through the use of BioChar and carbon-fiber-reinforced materials, carbon is permanently bound, whereby the wall construction contributes to the reduction of CO2 in the atmosphere.

[0005] The wall construction consists of two pressure-resistant panels sandwiched by an insulating layer of BioChar. The panels can be made of natural stone, engineered stone, concrete, ceramic, or glass. The BioChar insulation layer is highly porous and provides excellent thermal insulation while being lightweight. The carbon fibers, preferably made from biomass such as bioglycerin or lignin, stabilize the panels against tensile and bending loads. The load-bearing panels are bonded together with temperature-stable mineral adhesives such as high-temperature water glass to ensure structural integrity in the event of a fire. The use of gabbro rocks or other heat-resistant materials further contributes to safety and stability at high temperatures.

[0006] To optimize mechanical load-bearing capacity and minimize the risk of buckling of the thin panels, stiffening ribs are formed from temperature-resistant materials and integrated into the structure with the help of wood, glass, or ceramic to prevent thermal bridges. These ribs are designed to distribute loads evenly across the entire wall surface without creating thermal bridges. Another novel aspect of this invention is the use of rock or mineral flour generated during panel production. This flour, which is created when the panels are cut, has a high potential for enhanced weathering, in which CO2 from the atmosphere is permanently incorporated into the mineral structure. The use of weatherable stone for the construction of the wall offers an additional opportunity for CO2 sequestration and contributes to the climate-neutrality of the construction method.

[0007] The present invention describes a novel wall construction that is not only mechanically stable and thermally insulating, but also serves as an efficient CO2 sink. The integration of BioChar and carbon fiber-reinforced materials enables a sustainable and environmentally friendly construction method that actively contributes to the reduction of CO2 emissions. This construction offers a promising solution for modern, sustainable building construction by combining the advantages of natural stone and innovative materials to create a stable, lightweight, and environmentally friendly wall construction.

[0008] In contrast to EP08874021 and EP20702566, the present invention relates to the use of pure BioChar as a stiffening insulation layer which is optionally supported with rock wool.

[0009] This is primarily highly porous carbon, which is incorporated into the insulation layer. This carbon serves the purpose of providing good thermal insulation, reducing the weight of the insulation layer, and storing carbon in a highly concentrated form.

[0010] The present invention proposes a method for using stone or earthenware slabs, ceramic or artificial stone, or concrete slabs that are laid out as thin as possible, which are sustainably and inexpensively stabilized, thus becoming self-supporting wall elements in the process proposed here, while also being enabled to act as highly efficient carbon sinks. The stone, ceramic, or even glaze, and other pressure-resistant mineral materials—generally referred to here as earthenware—which previously represented additional weight for building construction purely as facade cladding, will now themselves become the load-bearing element of the house wall, and the insulation layer, together with the carbon fiber, when made from organic oil or organic lignin, for example, will become an efficient carbon sink. Due to its high temperature resistance, the stone 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. The bond between the fiber and the stone is created using temperature-stable water glass to provide lasting and long-lasting support for the stone in the event of a fire.

[0011] It is also 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, thus ensuring that the visible surface remains largely straight and level and does not sag.

[0012] 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 deformation, on the other hand, by a stabilization suitable for the respective application and load case. 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 the fact that the panels can be made of different materials with different expansion coefficients.

[0013] The core of the solution to find the most suitable insulation material for such self-supporting walls in sandwich construction is to keep the total expansion coefficient of the inner and outer panels as small as possible and, in particular, as equal as possible, to enable the absorption of carbon, to ensure good fire protection behavior and to have a high insulation value, as well as to be dimensionally stable, waterproof and frost-proof and to avoid thermal bridges.

[0014] Promising candidates for bonding the individual elements of such a wall are mineral adhesives that have sufficient flexibility and tensile strength to prevent buckling or other failure even in the event of a fire by bonding to the fiber-stabilized earthenware panels and applying the load.

[0015] 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. Compared to steel construction, weight and space are also saved 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.

[0016] The following is a structural description of the wall structure. The invention filed for patent application relates to the construction sector, particularly to building construction, 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.

[0017] 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 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 across the element. The element is thus protected against buckling and can absorb horizontal loads occurring across the element, such as wind loads.The load introduction and load transfer structure, made of well-insulating stone, from the floor slabs to this sandwich element, transfers the vertical loads symmetrically to the panes 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 elements is >= 75 kN / m. The elements are installed as pendulum supports in the ceilings at the top and bottom, using the structural principle. The thermal insulation values ​​can achieve the Swiss Minergie standard.

[0018] The thin slabs are made of a compressive and shear-resistant, waterproof material such as concrete, natural stone, glazed stone, 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 the most forgiving ductile material behavior possible. The sandwich core consists of a highly thermally insulating material made of BioChar. The load introduction consists of a thermally weakly conductive, compressive and shear-resistant element made of stone or wood, or a combination of stone and wood, which is force-fitted to the stone slabs with a mineral adhesive or dovetail galvanization, or both.

[0019] 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.

[0020] For the stabilization of 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 bioglycerin or lignin. These stabilize the stone either over a large area or only partially with individual rovings, preventing expansion and fracture. Natural stone itself has a very low temperature 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 or even completely prevented.The invention described here also relates to carbon fibers made from lignin, since these are cheaper than PAN-based fibers and have sufficient stiffness for the purpose described here when they are attached to the outside of the stone slabs as tensile reinforcement.

[0021] This innovation of using the fiber matrix on the outer surface of one or both load-bearing stone slabs to promote buckling of the flat slabs despite the relatively low stiffness of a lignin-based fiber is not described in previous applications. For aesthetic reasons and also as a protective function for the matrix, this fiber layer can then be covered with a thin layer of stone.

[0022] The result is a flat, compressive and tensile stress-resistant slab arrangement, which in this application ensures sufficient stabilization of the stoneware against cracking and breakage. This symmetrical assembly – fiber-stabilized stone slab – insulation cross-section – another fiber-stabilized stone slab – not only makes this slab arrangement visually attractive both indoors and outdoors, but also represents a completely new type of wall construction that, with the same load-bearing capacity, is about twice as light or can be made thinner than conventional house walls and building structures made of reinforced concrete.

[0023] The substrate material, hereinafter referred to as the substrate, 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 lasting stabilization for a more or less thin stone slab. By using temperature-stable mineral water glass adhesives in combination with, for example, carbon fibers, which have a negative coefficient of thermal expansion, 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 a wide temperature range, thus avoiding warping of the entire slab while still achieving a lightweight construction. To transfer the compressive forces that such a house wall must absorb 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 the walls from buckling. Wood is safe in the construction and can withstand even extreme temperatures when no air supply is available.In the case of the 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 slabs can absorb, transmit, and release a certain amount of water over extended periods of time, thus regulating the humidity balance between the interior and exterior spaces. The BioChar also exerts an additional effect here through its water absorption and release capabilities.If such walls are now additionally designed to have a high carbon content in the insulation layer, then this carbon not only improves the insulation properties and moisture regulation, and reduces the expansion coefficient and the weight of the insulation layer, but also turns the construction into a large carbon sink due to the high volume of the insulation layer relative to the load-bearing structure. This enables the achievement of climate goals through a building material adapted to the climate problem itself. While previous building materials have caused CO2 emissions, this new building material concept is intended to reverse CO2 emissions and help recapture and bind the CO2.

[0024] The supporting stone or mineral material layers play an important role in the invention as an additional CO2 sink. Depending on the type, the rock or mineral dust produced when cutting the slabs has a high weathering potential. When this dust or dust is exposed to water and CO2, carbonation processes occur that incorporate atmospheric carbon into the mineral structure in the form of CO2, thus permanently binding the carbon. This process is known in climate science as enhanced weathering of stone or enhanced weathering of rock (EWR) and promises to become a de facto infinitely scalable carbon dioxide sink if this dust can be spread in nature or on agricultural land.The stone dust is generated as waste during the house wall construction process, so it does not need to be milled using renewable energy, as initially assumed by climate scientists. The grain size and surface area typically generated during cutting of the slabs correspond to the values ​​predicted to be successful in climate models. EWR thus becomes part of a self-sustaining business model in a rapidly expanding construction sector in the future. This makes the entire construction a driving force for effectively affordable measures against climate change, as the overall cost balance is not fundamentally different from construction with steel and reinforced concrete. On the contrary, it requires less manufacturing energy and does not involve inherently CO2-emitting processes, as is the case with cement production. Gabbro rock, or basalt rock, has a weathering rate of 450 grams of CO2 per kilogram of stone dust.

[0025] In addition, the production of this house wall is highly CO2-negative due to the CO2 capture in the biochar and the stone dust, although calculations show that the CO2 capture in the coal and the stone dust is roughly balanced. The carbon fiber then contributes an additional portion to the CO2-negative effect if it can be permanently stored underground rather than incinerated after use.

[0026] The relatively loose insulation fill means that the load-bearing stone slabs must be stiffened to prevent buckling forces strong enough to break the wall slabs. This is achieved by longitudinally mounted stiffening ribs that are firmly connected to the stone slabs. These stiffening ribs must not form thermal bridges, which is why they do not meet in the middle of the wall. In addition, a force-fit connection is created at least in the middle using a material with poor thermal conductivity. In the event of a fire, the stone slabs, which lose their compressive strength at high temperatures, must still offer sufficient resistance to buckling forces. Since this material must also have not only low thermal conductivity but also the highest possible temperature resistance, wood, glass, or ceramic are used for this purpose, which represent a good compromise.This element should also not be connected to the opposite stiffening ribs by gluing, but should be manufactured purely mechanically using a force-locking geometry, for example by dovetail galvanization, as is common in timber construction.

[0027] As one of the many possible implementation examples, Fig. 1 shows the horizontal section through the wall. The wall is shown with two stone slabs (1) which are stabilized on the outside with a carbon layer with a water glass matrix (2). An insulation layer (3) made of a fill of CO2-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 ribs (5) with sufficient compressive and tensile strength 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 introduction points (4) at the top and bottom transfer the compressive forces into and out of the wall. Figures 2 and 3 show locations where the ribs are bonded with galvanizing. Figure 4 shows the wall with an internal and an external rib reinforcement at a location without galvanizing.Figure 3 shows the rib stiffeners, 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 filling can be mechanically supported by interwoven rock wool fibers.

[0028] 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 panels (1a) is stabilized with carbon fibers on the outside, and the other stone panel (1b) on the inside. Which of the two sides has the matrix fiber layer on the inside may depend, for example, on which stone panel is subjected to higher or longer-lasting thermal stress in the event of a fire. If the interior is subjected to higher thermal stress, it makes sense to coat the stone panel located in the interior with carbon fiber.

Claims

Patent claims 1) Load-bearing wall element for buildings with two symmetrically arranged load-bearing slabs made of stone, natural stone, artificial stone, ceramic, concrete, glazed or glass-containing material, - wherein a cross-sectionally increasing insulating layer of insulation material between both support plates stiffens the overall arrangement, wherein the support plates are stabilized with a fiber-containing temperature-resistant matrix, - 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-sectionally increasing insulation layer consists of a bed of CO2-based carbon with high porosity - and wherein the two carrier plates each consist of different or similar plate materials, the manufacturing waste flour of which has a high weathering rate. 2) Load-bearing wall element according to claim 1, characterized in that the layer of stabilizing fiber matrix is ​​arranged on the inside and / or outside of at least one of the load-bearing stone slabs and contains carbon fibers. 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 consists of pure BioChar. 5) Load-bearing wall element according to claims 1 to 4, characterized in that the carbon fiber originates from atmospheric CO2, which was obtained either from bio-based glycerin or bio-based lignin. 6) Load-bearing wall element according to claims 1 to 5, characterized in that the layer of carbon-based insulation material is mechanically supported by means of rock wool. 7) Load-bearing wall element according to claim 1 to 6, characterized in that the load-bearing plates are connected on the inner sides or the outer sides with their own stiffening rib or stiffening ribs at certain distances by means of temperature-resistant mineral adhesive. 8) Load-bearing wall element according to claims 1 to 7, characterized in that the mineral adhesive has a water glass base. 9) Load-bearing wall element according to claims 1 to 8, characterized in that the support plates are connected to one another in a force-locking manner in the case that the rib or all ribs are located on the inside. 10) Load-bearing wall element according to claims 1 to 9, characterized in that the force-locking connection of the ribs with the load-bearing plates is made by means of galvanizing. 11) Load-bearing wall element according to claims 1 to 10, characterized in that the force-fitting connection of the ribs to one another is made by means of a dovetail galvanization made of wood, cast iron or ceramic. 12) Load-bearing wall element according to claims 1 to 11, characterized in that the overall construction has a CO2-negative footprint, i.e. is CO2-negative and thus a carbon sink. 13) Load-bearing wall element according to claims 1 to 12, characterized in that at least one of the load-bearing stone slabs consists of gabbro and / or basalt rock.