Method for forming and fixing anchor elements on textile structures made of fibers for prestressed textile-reinforced concrete elements

Abstract

In this process, at least one prefabricated textile structure (1) made of fibers is positioned between two plate-shaped elements (2, 3) made of the same thermoplastic polymer and brought into contact with the textile structure (1). Energy is applied to heat the structure, enabling plastic deformation of the thermoplastic polymer. Once a suitable temperature is reached, pressure is applied from both sides, causing the plate-shaped elements (2, 3) to move towards each other. This plastic deformation of the thermoplastic polymer results in material exchange between the plate-shaped elements (2, 3). The plate-shaped elements (2, 3) are then moved towards each other. Finally, the structure is cooled to ambient temperature.This results in a non-interfacial, materially bonded connection with thermoplastic polymer of the plate-shaped elements (2, 3) to form an anchor element (7) on a textile structure (1) that has been embedded in the thermoplastic polymer.

Description

[0001] The invention relates to a method for forming and fixing anchor elements on textile structures made of fibers for prestressed textile-reinforced concrete elements.

[0002] The invention can be particularly advantageously applied to a technical solution such as that described in DE 10 2016 211 176 A1.

[0003] Prestressed concrete elements are classically defined as concrete elements reinforced with steel and subjected to tensile stresses on the reinforcement, as well as so-called prestressed concrete elements. These can withstand higher external tensile stresses than concrete elements that are not prestressed.

[0004] In recent years, textile-reinforced concrete elements have also been developed and used. These offer advantages over conventional concrete elements because, due to the lower risk of corrosion, they require significantly less concrete than those with steel reinforcement. Textile-reinforced concrete elements are manufactured using textile structures embedded in concrete. These textile structures can be, for example, woven fabrics, knitted fabrics, non-woven fabrics, spun fabrics, or other types of textiles made from a wide variety of fibers. In addition to glass fibers, fibers made from ceramic or organic materials, and especially suitable carbon fibers for so-called carbon concrete components, can be used to produce suitable textile structures. The fibers can be processed into textile structures in various forms, such as spun yarns or rovings.

[0005] If concrete structural elements are to be provided that are prestressed with tensile stresses, it is necessary to form anchor elements on the reinforcements or textile structures provided for this purpose, or such anchor elements should be present there that serve as force application points where the required tensile forces for prestressing can be applied and maintained until the concrete in which the respective prestressed reinforcement or the textile structures have been embedded has sufficiently set or hardened to withstand the tensile stresses.

[0006] With steel reinforcements, it is relatively easy to design or attach suitable anchor elements to reinforcing bars. With textile structures, this is considerably more difficult and complex, as, for example, sufficient deformation or a positive-locking attachment of anchor elements, as with steel, is not possible.

[0007] For example, due to their sensitivity to transverse pressure, fibers in textile structures can be damaged if hard anchor elements are rigidly attached to the fibers. This can even lead to cracking, preventing the desired prestress from being achieved in a concrete element.

[0008] The production of anchor elements using liquid polymer, which is poured into the spaces within a textile structure similar to concrete and then cured, also has its drawbacks. For example, this method requires complex molds to create defined anchor elements. These molds must be sufficiently dense and easily positioned relative to the textile structure to ensure the anchor elements are located correctly and have the desired shape and size. Furthermore, the relatively long curing time required is a significant disadvantage, further impacting productivity.

[0009] The object of the invention is therefore to provide possibilities for a simplified, safer and more productive design and fixing of anchor elements to textile structures, which in turn are to be used for the production of prestressed concrete elements.

[0010] According to the invention, this problem is solved by a method having the features of claim 1. Advantageous embodiments and further developments of the invention can be realized with features specified in dependent claims.

[0011] In the method according to the invention, in a first alternative according to the invention, in which at least one prefabricated textile structure formed from fibers which are particularly insensitive to heating and which may thereby change certain physical properties that do not adversely affect their strength, is placed in an edge region between two plate-shaped elements which are formed from the same thermoplastic polymer, or between at least two plate-shaped elements formed from a metal or a ceramic material and coated with the same thermoplastic polymer at least on the respective surfaces that are oriented towards a textile structure, arranged so that fibers of the textile structure are brought into contact with the surfaces of the plate-shaped elements facing each other.

[0012] By introducing energy in the area where the plate-shaped elements are in contact with fibers of the textile structure or are brought into contact with them, the thermoplastic polymer is heated to a temperature above its glass transition temperature, thus reaching the flow zone that allows plastic deformation of the thermoplastic polymer.

[0013] However, this temperature is at least 20 K below the decomposition temperature of the thermoplastic polymer.

[0014] Once this temperature is reached, a pressure of at least 0.1 MPa and at most 2 MPa is applied to the plate-shaped elements from both sides. This causes the plate-shaped elements to move towards each other, resulting in plastic deformation of the thermoplastic polymer and an exchange of material between the plate-shaped elements.

[0015] In a second alternative according to the invention, which is preferably used for temperature-sensitive fiber materials, the method is carried out such that at least one textile structure with its edge region is positioned at a distance from two plate-shaped elements formed from the same thermoplastic polymer, or between at least two plate-shaped elements formed from a metal or a ceramic material and coated with the same thermoplastic polymer at least on the respective surfaces that are oriented towards a textile structure. arranged so that the surfaces of the plate-shaped elements can be heated under the influence of energy.

[0016] In this process, energy is introduced into the area where the plate-shaped elements, which are not in physical contact with fibers of the textile structure, heat is achieved in the thermoplastic polymer, at which point the respective thermoplastic polymer has reached a temperature above its glass transition temperature and the flow zone, which allows plastic deformation of the thermoplastic polymer, has been reached.

[0017] However, this temperature is at least 20 K below the decomposition temperature of the thermoplastic polymer.

[0018] Then, within a time interval of a maximum of 5 s, preferably a maximum of 3 s, a relative movement occurs between the plate-shaped elements (2, 3) and the at least one textile structure (1), such that surfaces of the plate-shaped elements (2, 3) in an edge region of the at least one textile structure (1) are brought into contact with surfaces of the at least one textile structure (1). In both alternatives according to the invention, after reaching or maintaining this temperature, a pressure of at least 0.1 MPa and at most 2 MPa is exerted on the plate-shaped elements from both sides. The plate-shaped elements are moved towards each other in such a way that the thermoplastic polymer is plastically deformed and a material exchange of the thermoplastic polymer between the plate-shaped elements is achieved.

[0019] The plate-shaped elements are moved towards each other until a maximum deformation of the plate-shaped elements in the direction of the compressive force of 5 mm or a maximum of three times the circumference of fibers of the textile structure has been achieved.

[0020] Subsequently, cooling to ambient temperature takes place and a non-interfacial, material-bonded connection with thermoplastic polymer of the plate-shaped elements is achieved to form an anchor element on a textile structure that has been embedded in the thermoplastic polymer.

[0021] Cooling can be accelerated if temperature control is provided by supplying a suitably tempered coolant.

[0022] It is particularly advantageous that a material exchange of thermoplastic polymer takes place from the various plate-shaped elements, which leads to a homogeneous polymeric material in the area where the material-bonded connection is achieved and where there are no interfaces that could lead to delamination effects.

[0023] To apply and allow tensile stresses to act on a textile structure when one or more textile structures are encased in sufficiently viscous concrete, it is necessary to form at least one additional anchor element on each textile structure and connect it to the textile structure using a material-locking and / or form-locking procedure. This additional anchor element should be formed diametrically opposite to the first anchor element on the respective textile structure and fixed there.

[0024] Coated, plate-shaped elements can be used in which the surface coating made of thermoplastic polymer is bonded to a metallic or ceramic element in a material-locking and / or form-locking manner. For example, contour elements can be present on the surfaces of metallic or ceramic elements in the form of raised areas and / or recesses and / or openings in these elements, in which the thermoplastic polymer of a corresponding coating can be fixed in a form-locking manner.

[0025] On its own or in addition, the coating made of thermoplastic polymer on surfaces of metallic or ceramic elements can have a thickness that is at least twice the thickness of the respective textile structure without any pressure being applied.

[0026] The heating of polymeric or appropriately coated plate-shaped elements can be achieved in a variety of ways. For example, mechanical or kinetic energy can be used to generate heat through vibrations or friction. However, heating via thermal conduction or convection using a radiation source that emits electromagnetic radiation or heat towards at least one plate-shaped element is more advantageous.

[0027] The heating of the thermoplastic polymer can thus be achieved with at least one radiation source that emits electromagnetic radiation within a wavelength range between 0.3 µm and 3 µm.

[0028] The plate-shaped elements should be arranged during heating in such a way that the heating process is as undisturbed as possible by other elements, especially by directly incident electromagnetic radiation. This is particularly important in the second alternative procedure, as it aims to prevent electromagnetic radiation from directly impacting the fibers of a textile structure. If the surfaces of plate-shaped elements are heated alone, i.e., without simultaneously heating textile structures, the relative movement of the plate-shaped elements, heated to a suitable temperature, with respect to their respective positions on the surfaces of textile structures should occur within a time interval that allows for slight cooling while still maintaining sufficient plastic deformability of the thermoplastic polymer.In relative movement, plate-shaped elements and textile elements can each be moved individually for the desired positioning, or both different elements can be moved together.

[0029] At least one anchor element can be formed with several textile structures arranged side by side and / or one above the other, or with more than two plate-shaped elements. If more than one textile structure is arranged one above the other in different planes, at least one plate-shaped element can be bonded to textile structures between the planes. Coated plate-shaped elements should then be coated with the polymer on the two corresponding surfaces or consist entirely of the polymer.

[0030] It is therefore also possible to arrange several textile structures side by side in a plane and, as already described, to connect them to each other with at least two plate-shaped elements starting from two opposite surfaces. The textile structures can be arranged parallel to each other and directly next to each other in the same plane, or at appropriate, preferably equal, distances from each other when connected with the plate-shaped elements.

[0031] However, several textile structures can also be arranged in different planes at intervals from each other, with at least one plate-shaped element placed between the planes in a plane above or below (or next to each other, depending on the orientation of the planes) before heating and the resulting bond is achieved through pressure.

[0032] This makes it possible to provide prefabricated textile structures equipped with anchoring elements, which can be designed in a wide variety of dimensions and for a wide variety of applications. Their width and thickness can vary depending on how many textile structures are arranged side by side or on top of each other and fitted with anchoring elements.

[0033] If one or more textile structures are arranged next to each other, plate-shaped elements should be arranged and used in such a way that at least 90% of the width of the textile structure(s) is covered perpendicularly in relation to the direction of the tensile forces acting on the respective prestressed concrete element.

[0034] Plate-shaped elements made of or coated with polypropylene (PP), acrylonitrile butadiene styrene (ABS), polyamides (PA), polylactide (PLA), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene (PE), polystyrene (PS), polyetheretherketone (PEEK) and polyvinyl chloride (PVC) should be used.

[0035] During the heating of the thermoplastic polymer and / or during the plastic deformation of the thermoplastic polymer due to applied compressive forces, the temperature reached on plate-shaped elements and / or the distance traveled and / or the rate of plastic deformation should be determined and, if necessary, monitored. This can be done with suitable sensors. Their measurement results can be used to control the plastic deformation by influencing the applied compressive forces of the feed mechanism, thus influencing the speed of the movement of the plate-shaped elements towards each other and / or limiting their path length.

[0036] Plate-shaped elements can be used which, as a starting point and also after being attached to a textile structure, have a rectangular, square, other polygonal, circular, oval, elliptical, or multiply curved outer edge geometry.

[0037] The invention will now be explained in more detail using a particularly advantageous example.

[0038] This shows: Fig. 1. In schematic form, the procedure for the formation and firm connection of an anchor element with a textile structure and two plate-shaped elements in two steps and Fig. 2 in schematic form a possibility for the formation and fixing of an anchor element with several textile structures and plate-shaped elements arranged between them.

[0039] In the upper representation of Fig. Figure 1 shows how, in an example, two plate-shaped elements 2 and 3 are arranged at a distance 4 from each other and aligned parallel to each other. In this position, heating advantageously takes place until the temperature or a corresponding temperature range mentioned in the general part of the description has been reached.

[0040] Then, as shown in the illustration below, the following occurs: Fig. Figure 1 shows the insertion of a textile structure 1 between the sufficiently heated plate-shaped elements 2 and 3, before the compressive forces act on the two outwardly facing surfaces of the plate-shaped elements 2 and 3 and the plastic deformation is carried out, in which the embedding of the textile structure in the thermoplastic polymer with the material exchange takes place.

[0041] Fig.Figure 2 shows schematically how n textile structures 1 can be arranged between plate-shaped elements 2 or 3 and joined together to form an anchor element 7. The textile structures 1 and the plate-shaped elements 2 or 3 are arranged one above the other in different planes, parallel to each other.

[0042] For example, an anchor element 7 for two superimposed textile structures 1 can be produced with a plate-shaped element 2, made of thermoplastic polymer, lying on top of the textile structure 1, a plate-shaped element 3, made of the same thermoplastic polymer, arranged between the two textile structures 1, and a plate-shaped element 2, also made of the same thermoplastic polymer, arranged below the second textile structure 1.

[0043] Instead of a horizontal alignment of the plate-shaped elements 2 and 3 made of the thermoplastic polymer and the textile structures 1, these can also be aligned vertically and parallel to each other.

[0044] In any case, the relative positions of the three plate-shaped elements 2 and 3 and the textile structures 1 should be selected in a procedure according to the second alternative of the invention such that, after reaching a temperature greater than the glass transition temperature and at which the flow regime enabling plastic deformation of the thermoplastic polymer has been reached, the required relative movement of the plate-shaped elements 2 and 3 with respect to the textile structures 1 can take place within a time interval T < 2 s, during which the pressure specified in the general part of the description is exerted from the outside on the surfaces of the externally arranged plate-shaped elements 2. Before all the plate-shaped elements 2 and 3 involved, which consist of the same thermoplastic polymer, and the textile structures 1 are brought into contact with each other, the plate-shaped elements 2 and 3 and, if applicable, the textile structures 1, are pressed together.The textile structures 1 are also positioned according to at least one radiation source, preferably at least two radiation sources, which emit electromagnetic radiation from the outside onto externally arranged plate-shaped elements 2.

[0045] The textile structures 1, which are considerably bulkier and more sensitive to handling, or whose fibers are more temperature-stable, can also remain stationary according to the first alternative of the invention. In such an example, they remain in the originally prepared position, in which plate-shaped elements 2 and 3 are in contact with the textile structure, and heating takes place in this position. The plate-shaped elements 2 and 3, which consist of the thermoplastic polymer, are then moved relative to radiation sources and positioned accordingly so that simultaneous heating of the plate-shaped elements 2 and 3 with the textile structure(s) 1 is achieved by means of the electromagnetic radiation emitted by the radiation sources.

[0046] When the temperature of the second alternative according to the invention has been reached, which lies within the flow range and at which plastic deformation of the thermoplastic polymer is possible, the corresponding heated plate-shaped elements 2 and 3 should be repositioned in relation to the textile structures 1 so that an anchor element can be connected at the intended position. This should take place within the aforementioned time interval T.

[0047] For heating the plate-shaped elements 2 and 3, individual radiation sources can be used, which should preferably be individually controllable or also be able to be switched on or off in a controlled manner.

[0048] In the case of two textile structures 1 arranged one above the other, the plate-shaped element 2 arranged above and below can also be heated on one side by irradiating them with electromagnetic radiation from corresponding directions. The plate-shaped element 3 arranged in the middle heats up accordingly due to thermal conduction when the procedure according to the first alternative of the invention is followed. If this procedure is followed, the plate-shaped elements 2 and 3 can already be positioned relative to the textile structures 1 as they are intended to be for pressing together to plastically deform the thermoplastic polymer of the plate-shaped elements 2 and 3 to form an anchor element 7.

[0049] The suitable flow range of the thermoplastic polymer from which the plate-shaped elements 2 and 3 are made can be determined at a beam power of approximately 10 W / cm². 2The temperature of the radiation sources used is reached after approximately 60 seconds. Higher radiation intensities and a smaller distance between the radiation sources and the surfaces of the plate-shaped elements 2 and 3 to be irradiated enable a higher process dynamic, i.e., heating in a shorter time.

[0050] After reaching the temperature for the flow range of the thermoplastic polymer from which the plate-shaped elements 2 and 3 are made, the plate-shaped elements 2 and 3 can also be moved back to their original relative position above, between and below the two textile structures 1 and arranged so that they are in touching contact of their respective surfaces, if the second alternative of the invention is to be used.

[0051] After reaching this position, pressure is applied to the outwardly facing surfaces of the plate-shaped elements 2 for 60 s and at a pressure of 0.2 MPa the plate-shaped elements 2 and 3 are pressed together and thermoplastic polymer embeds the fibers of the textile structures 1.

[0052] Compressive forces act upon the plate-shaped elements 2 and 3, causing movement and plastic deformation. The fibers of the textile structures 1 are embedded in the thermoplastic polymer, and material exchange occurs between the thermoplastic polymer of the heated and deformed plate-shaped elements 2 and 3.

[0053] In this example, plate-shaped elements 2 and 3, which consisted of polypropylene, were joined together with textile structures 1, which were prefabricated as fabrics with carbon fibers, in a material- and form-fitting manner, without any interfaces occurring within the thermoplastic polymer in the correspondingly manufactured anchor element 7.

[0054] To cool it to a temperature below the glass transition temperature of the thermoplastic polymer, a textile structure 1 equipped with at least one anchor element 7 can be placed in a prepared tray trolley. It can then be stored there as a semi-finished product for the production of prestressed concrete elements. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2016 211 176 A1

[0002]

Claims

[1] Method for forming and fixing anchor elements on textile structures made of fibers for prestressed textile-reinforced concrete elements, wherein at least one prefabricated textile structure formed from fibers (1) in an edge area between or at a distance from two plate-shaped elements (2, 3) formed from the same thermoplastic polymer, or between or at a distance from at least two plate-shaped elements (2, 3) formed from a metal or a ceramic material and coated with the same thermoplastic polymer at least on the respective surfaces that are oriented towards a textile structure (1), is arranged such that fibers of the textile structure (1) are brought into contact with the surfaces of the plate-shaped elements (2, 3) facing each other, or are arranged at a distance from the at least one textile structure (1) so that energy can be supplied to the plate-shaped elements (2, 3) from the outside and subsequently by an energy input in the area in which the plate-shaped elements (2, 3) are in contact with fibers of the textile structure (1) or the plate-shaped elements (2, 3) are arranged at a distance from the at least one textile structure (1), a heating of the thermoplastic polymer is achieved, at which the respective thermoplastic polymer has reached a temperature that is above the glass transition temperature and the flow range that allows plastic deformation of the thermoplastic polymer has been reached, and the temperature is at least 20 K below the decomposition temperature of the thermoplastic polymer and the plate-shaped elements (2, 3), which are arranged at a distance from the at least one textile structure (1), are moved within a maximum of 5 s so that they are positioned in relation to the at least one textile structure (1) in such a way that they are in contact with the surfaces of the at least one textile structure (1) at the position where the respective anchor element (7) is to be produced and After reaching or maintaining this temperature, a pressure of at least 0.1 MPa and at most 2 MPa is exerted on the plate-shaped elements (2, 3) from both sides, whereby the plate-shaped elements (2, 3) are moved towards each other, the thermoplastic polymer is plastically deformed and a material exchange of the thermoplastic polymer between the plate-shaped elements (2, 3) is achieved and the plate-shaped elements (2, 3) are moved towards each other to such an extent that a maximum deformation of the plate-shaped elements (2, 3) in the direction of the compressive force of 5 mm or a maximum of three times the circumference of fibers of the textile structure (1) has been achieved and subsequently Cooling to ambient temperature is achieved and a non-interfacial, material-bonded connection with thermoplastic polymer of the plate-shaped elements (2, 3) is achieved to form an anchor element (7) on a textile structure (1) that has been embedded in the thermoplastic polymer. [2] Method according to claim 1, characterized by , that plate-shaped elements (2, 3) are used in which the surface coating made of thermoplastic polymer is materially and / or form-fittingly connected to a metallic or ceramic element and / or the coating made of thermoplastic polymer on surfaces of metallic or ceramic elements has a thickness that is at least twice the thickness of the respective textile structure (1) without any compressive force being applied. [3] Method according to any one of the preceding claims, characterized by, that the heating is achieved by means of thermal conduction or convection with a radiation source with electromagnetic radiation emitted in the direction of at least one respective plate-shaped element (2, 3). [4] Method according to any one of the preceding claims, characterized by , that an anchor element is formed with several textile structures (1) arranged next to and / or on top of each other or with more than two plate-shaped elements (2, 3) when more than one textile structure (1) is arranged in multiple layers on top of each other in different planes. [5] Method according to any one of the preceding claims, characterized by, that one or more textile structures (1) are arranged next to each other and plate-shaped elements (2, 3) are arranged and used in such a way that at least 90% of the width of the textile structure(s) (1) is covered perpendicularly in relation to the direction of the tensile forces acting on the respective prestressed concrete element. [6] Method according to any one of the preceding claims, characterized by , that plate-shaped elements (2, 3) are used which are made of or coated with polypropylene (PP), acrylonitrile butadiene styrene (ABS), polyamides (PA), polylactide (PLA), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene (PE), polystyrene (PS), polyetheretherketone (PEEK) and polyvinyl chloride (PVC). [7] Method according to any one of the preceding claims, characterized by, that the heating of the thermoplastic polymer is achieved with a radiation source that emits electromagnetic radiation within a wavelength range between 0.3 µm and 3 µm. [8] Method according to any one of the preceding claims, characterized by , that during the heating of the thermoplastic polymer its temperature and / or during the plastic deformation of the thermoplastic polymer as a result of acting compressive forces the distance traveled and / or the speed of the plastic deformation is / are determined and monitored. [9] Method according to any one of the preceding claims, characterized by , that plate-shaped elements (2, 3) are used which have a rectangular, square, other polygonal, circular, oval, elliptical, multiply curved outer edge geometry. [10] Method according to any one of the preceding claims, characterized by, that after reaching the temperature at which the respective heated thermoplastic polymer has reached and exceeded the flow range, the compressive forces for plastic deformation are applied by means of press punches or pressure rollers.

Images