Reinforcement for cement-based structures, having undulating surface geometry

Abstract

The invention relates to reinforcement lamellae made of multi-layered stone and fiber material, characterized in that the surfaces of the lamellae at least partially have a symmetrically or asymmetrically undulating or toothed geometry along the cutting contour.

Description

[0001] Reinforcement for cement-based structures with corrugated surface geometry

[0002] Reinforced concrete is a combination of cement-based mineral mixture and steel reinforcement to provide the mineral component with the missing tensile stability.

[0003] This allows the mineral component to absorb pressure without breaking or failing under static or dynamic loads. This makes the material suitable for use in the construction industry for buildings, bridges, and other structures and their components, such as prefabricated beams, walls, ceilings, floors, or even railway sleepers.

[0004] The connection therefore functions excellently under changing temperature conditions, which buildings are usually exposed to during operation, because the thermal expansion coefficients of steel and concrete are virtually identical at approximately 10-12 x 10^ / K. The thermal expansion coefficients for the various materials are determined, for example, using a dilatometer, with the respective linear expansion coefficients expressed in units (K 1 ) must be specified.

[0005] For various reasons, the steel insert has its limitations, on the one hand, in terms of its longevity being limited by rust, and on the other hand, steel has come under criticism from climate research due to the high CCh emissions during the production of crude steel as a mass application, since about 50% of all steel produced today is used in the construction sector in the form of reinforcement material for concrete.

[0006] Unlike steel, other tensile-stable materials can be used as reinforcement, which are less energy- and CCE-intensive. However, the excellent fit of rolled section steel with concrete is difficult to achieve with other materials at such a low cost. For this reason, the invention proposed here goes a step further in paving the way for materials to replace steel in concrete structures, thereby becoming more environmentally friendly without being too disruptive or simultaneously challenging many existing industries. Initially, only steel as reinforcement for concrete will be replaced.

[0007] The invention is based on the previous patented inventions for using fiber materials to stabilize all types of stone materials. This is EP 106 20 92, which describes how stone materials, as they occur in nature, can be made more flexible by reinforcing them with carbon fibers. Stone and carbon have the perfect properties to remain stable over a wide temperature range without separating. The further invention EP 08 850 003.8 describes why this works. The porosity of the stone compensates for the different expansion coefficients through volume compressibility as long as the stone is under compressive prestress. This manifests itself in the form of flexibility. The thermal expansion coefficient of the stabilizing fiber is less than or equal to that of the stoneware to be stabilized.

[0008] WO 2013 / 026566 A1 describes structures made of carbon and basalt rock. Even basalt has the necessary flexibility to remain stable and straight with the carbon fiber over a wide temperature range without the stone layer detaching from the carbon layer, even though basalt is a rather inflexible natural stone. The coefficient of thermal expansion of the stabilizing fiber layer is even smaller than that of the directly bonded basalt rock.

[0009] The same applies to the two patent applications WO2014 / 086481 Al and WO 2009 / 129839 Al; the thermal expansion coefficient of the fiber layer is in each case smaller or similar to that of the stone material to be stabilized. EP3723976 describes that a specific intermediate material is the solution to the problem that the different thermal expansion coefficients of concrete and carbon fibers must be addressed so that the composite maintains a permanently crack-free bond between the reinforcement and the concrete interface during changing temperatures. This is achieved, for example, with natural stone, which has an expansion coefficient exactly midway between that of the concrete and the reinforcing carbon fiber, in the "sweet spot" with almost the same difference in both directions, and which, due to its porous surface, creates a perfect bond with the concrete.This intermediate material, which has a thermal expansion coefficient that lies between that of the materials to be combined, also has a flexible structure based on its volume compressibility due to a porous crystal structure.

[0010] This porosity is the reason for the good bond between the rock as an intermediate layer and the matrix that binds the fibers, typically a two-component synthetic resin on one side and the concrete on the other. The resin also achieves optimal adhesion to the porous stone surface. The shape, such as a serpentine geometry of the entire reinforcing bar or lamella, should also contribute to this, as suggested in Figure 1 in EP3723976.

[0011] However, EP3723976 only deals with this elementary feature in a non-specific manner, since the serpentine shape of the entire bar does indeed represent a possibility to improve the anchoring in the composite and to make it more difficult to pull out the lamella, which in practice is only possible with great effort, giving the entire bar a serpentine shape, which also allows an undesirable stretching of the lamella and thus also of the tensile reinforcing fiber if the entire lamella has a serpentine shape, which reduces the stiffness of the reinforcement.

[0012] This new invention describes an optimized surface shape that compensates for these disadvantages. The invention describes reinforcing lamellas characterized by the fact that the surface of the lamellas only partially exhibits a corrugated geometry or a counter-directional corrugation.

[0013] For improved stabilization through optimized force transfer of concrete through a targeted geometry of the lamella surface along the cutting contour, which simultaneously utilizes compression of the lamella under load, so-called CFS lamellas (CFS - Carbon Fiber Brick) are described below. These propose a symmetrical or asymmetrical geometry of the lamella surface in the concrete bed with respect to the longitudinal axis. In contrast to the serpentine shape of the lamella axis itself proposed in the arrangement in EP3723976, a straight lamella axis with, for example, a mirror-symmetrical waveform along the axis or a section through a mirror-symmetrical waveform along the straight axis is proposed.The wave pattern on both sides can also be asymmetrical with respect to the axis, as long as the entire lamella does not always have wave peaks and troughs at the same position, i.e. it does not deliberately have a uniform serpentine shape, as suggested in EP3723976.

[0014] Otherwise, the wavy surface of one side can be completely asymmetrical with respect to the wavy surface on the other side, as explicitly shown in Figure 3.

[0015] Figure 2 shows a concrete module (1) stabilized with a strip (lamella) of fiber-coated granite (2). The flat carbon fiber layer (3) is located between the two essentially flat stone layers, having little or no direct contact with the concrete, except for the end faces on the sides and the heads created by a cut through an essentially flat slab. The shape of the cut contour line (5) determines the frictional bond between the lamella and the concrete. The thickness of the stone layer determines the temperature range within which detachment of the layers is not exceeded due to the stress of the differently expanding materials. The tolerable temperature range increases with the ratio of the thickness of the stone layers to the thickness of the carbon layer.By avoiding a serpentine shape of the lamella, the tensile stress of the fiber layer remains linear and is not deflected by a curved course of the lamella axis. Nevertheless, the lamella cannot be pulled out of the concrete by the corrugated surface. Due to the consistently linear course of the forces, a crushing of the lamella in the concrete form occurs under load, which creates high friction forces that increase the adhesion between the lamella surface and the concrete under load. Figure 1 shows a symmetrical course of the corrugated surfaces of the lamella on the top and bottom with respect to the longitudinal axis (4), and Figure 4 shows the geometry with a one-sided wave shape of the lamella surface on one side, while the other side has a straight surface.Figure 5 shows that the lower surface is only half-waved along the entire length of the slat. This tapers in the middle, causing the slat to be pulled into a bottleneck formed by the surrounding concrete block when the concrete block is subjected to bending load. This pushes the stone layers into the middle, firmly clamping the carbon fiber layer between the two stone layers. Figure 6 shows a slat with a significantly wider geometry at both ends. This ensures that the tensile forces are optimally transmitted along the entire length of the slat right up to the ends. The ends are also protected from being pulled out of the concrete material due to overload and find an optimal anchor at the ends. This is particularly helpful in the event of a fire, when temperatures are higher in the middle of the room than near the walls.This can be advantageous in the stabilization of concrete slabs in the event of a fire, when the resins fail at high temperatures, and the carbon fibers are then held to the porous stone surface only by frictional forces, preventing the tensile reinforcement of the carbon fibers from failing. This case is best addressed by the configuration in Figure 6. Figure 7 shows the section contour line of the lamella with a view from one of its sides. Notches (8) are provided on the stone surfaces at the top and bottom ends (6) and bottom (7), which improve load transfer at the ends.

[0016] In all cases, the matrix-bonded long-fiber layers can consist of carbon fibers, glass fibers, or stone fibers, or a mixture of these fibers, and ideally keep the stone material under prestress, as described in EP 08 850 003.8. Ideal adhesion between cement and stone is achieved when the stone has a rough surface and, ideally, is not completely linear, for example, it has grooves at regular intervals on both sides or surfaces and / or, if appropriate, has a symmetrical or only one-sided undulation, which improves the adhesion between stone and concrete by squeezing the intermediate layer of fibers under load. The matrix, which creates the bond between the fibers and the stone material, consists either of synthetic resins or water glass-based binders; here, too, a rough stone surface is helpful.All high-tensile long fibers that are suitable for reinforcing concrete as a replacement for steel are used as fibers. These include, in particular, unidirectionally laid carbon fibers, but also highly rigid glass fibers and stone fibers or, under certain circumstances, natural fibers or a mixture of these fibers.

Claims

Claims 1) Arrangement with a plate or a block or any geometry of a component made of concrete, cement-based mineral, which is stabilized by means of one or more lamellae consisting of fiber materials and an intermediate layer, wherein as an intermediate layer between concrete or cement-based mineral and the fiber material a stone material is used with a thermal expansion coefficient that lies between the thermal expansion coefficient of the respective concrete, cement-based mineral used and the thermal expansion coefficient of the respective fiber used, wherein the respective thermal expansion coefficient is in the unit K' 1can be determined by measurement, characterized in that the cutting contour lines of the essentially flat lamella have a wave shape or toothing running in opposite directions on both sides with respect to its longitudinal axis, or have a wave shape or toothing only on one side and a flat, straight or slightly curved contour on the respective opposite other side. 2) Arrangement according to claim 1, characterized in that the cut contour surfaces of the lamella have a symmetrical wave shape with respect to its longitudinal axis. 3) Arrangement according to claim 1 and 2, characterized in that the stone material is a natural stone, artificial stone or ceramic. 4) Arrangement according to claim 3, characterized in that the fibers stabilizing the stone are either carbon fibers, glass fibers, stone fibers or natural fibers or a mixture of these fibers. 5) Arrangement according to claims 1 to 4, characterized in that the stone layers are prestressed by the fiber. 6) Arrangement according to claims 1 to 5, characterized in that the fibers are bound with resin or water glass and connected to the stone. 7) Arrangement according to claims 1 to 6, characterized in that the fiber-reinforced lamellae have a rough surface. 8) Arrangement according to claims 1 to 7, characterized in that the fiber-reinforced lamellae have a non-linear, toothed shape along the cutting contour line. 9) Arrangement according to claim 8, characterized in that the fiber-reinforced lamellae have a bottleneck contour. 10) Arrangement according to claims 1 to 9, characterized in that the slats have grooves, notches or depressions at certain intervals which improve the frictional connection between stone and concrete or cement. 11) Arrangement according to claims 1 to 10, characterized in that the layer of the carbon layer is wider than it is high. 12) Arrangement according to claims 1 to 11, characterized in that the lamella is made stronger or thicker at one end or both ends than in the middle or in the parts between the reinforced ends. 13) Arrangement according to claims 1 to 12, characterized in that the reinforcing structures made of stone-carbon-stone shown in Figure 2 consist of a plurality of lamellae. 14) Arrangement according to claims 1 to 13, characterized in that the reinforcing structures made of stone and fibers are used as a bottom chord for the renovation of concrete bridge construction or as reinforcement of concrete ceilings. 15) Arrangement according to claims 1 to 14, characterized in that the lamella has notches at least at one end or both ends or over the entire length on the substantially flat underside and / or upper side, which increase the frictional connection between the lamella and the concrete embedding, in particular at the ends.

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