A method and a dowel system for securing insulation in concrete elements

Abstract

 A method and a dowel system for attaching insulation materials (9) in the prefabrication of insulated concrete elements, comprising a dowel head and an attachment part. The attachment part comprises a wire having an essentially rectilinear wire member (7) and a hook part, and the dowel head comprises an anchoring disc (1) and a pipe part (2) having a through bore (5,6), through which bore (5,6) the straight part of the wire member (7) is inserted in connection with the attachment of the dowel head. The anchoring disc moreover has an opening in the form of a slot (3) in the anchoring disc and the pipe part (2). It is preferred that the pipe member (8) is placed around the wire member (7) in the bore (5) in connection with the attachment of the dowel head, and that the slot (3) has a width which also allows passage of the pipe member (8) when the wire member (7) and the pipe member (8) are bent for attachment of the dowel head and thereby attachment of the insulation material (9) on the concrete element.

Description

[0001] The invention relates to a method of attaching insulation material to a concrete element with a dowel system, said dowel system comprising an attachment part and a dowel head.

[0002] Moreover, the invention relates to a dowel system for attaching insulation material to a concrete element, which comprises an attachment part and a dowel head.

[0003] Finally, the invention relates to use of a dowel system according to the invention for attaching insulation material in the prefabrication of concrete elements.

The prior art

[0004] The commercially available dowels are all based on securing insulation to existing faces, such as facades - roof surfaces - foundation walls, etc. This means that they are based on subsequent insulation/replacement of insulation on existing faces of the above-mentioned building parts.

[0005] Therefore, the known dowels are constructed such that they are secured mechanically with a screw or an expansion part in the existing faces. The dowels are mounted in that they are drilled through the insulation and into the existing faces, such as brickwork, leca concrete, gas concrete, concrete, wooden bases, etc.

[0006] An example of this may be seen in DE 10139261 A1, in which, during the manufacture of an insulation layer, a sleeve is inserted, which extends through the insulation layer, and a dowel screw is screwed through this sleeve into the wall or the surface.

[0007] It is characteristic of all these known dowels that they must have a firm base in order to be secured. Moreover, all the existing dowels are vitiated by the drawback that it cannot be seen whether the dowels are screwed sufficiently far into the existing faces, since the insulation layer makes it impossible to see the face in which the dowels are to be anchored. This may mean that the dowels are not properly secured in the face, which involves the risk of a defective element, as the carrying capacity in the attachment of the insulation is impaired in the element, if there are many dowels which have not been secured sufficiently in the face. This is a problem, especially if the concrete element is constructed with a surface on top of the insulation layer which is also secured by the dowels, or if one or more plaster coats are applied directly to the outer surface of the insulation, e.g. as described in EP 2224071 A1.

[0008] When insulation is to be secured in connection with the production of prefabricated concrete elements, there is also a problem with "the firm base". Either, the base is too fresh to anchor anything, if it is desired that the insulation and thereby also the dowels are mounted rapidly after the casting of the concrete elements. Alternatively, the mounting of the insulation and the dowels must be postponed until the concrete element has hardened, following which the above-mentioned known dowels will have to be used for mounting in the now firm base. However, this means that the overall production time of the concrete element is long, since the concrete hardening time is included as an independent step in the production of the concrete element. It takes about 12 hours for the concrete to harden to such a sufficient degree as will allow the known dowels to be attached in the faces of the concrete elements. Thus, it is not possible to produce the concrete element in one day with the existing dowel systems or dowels for the anchoring of the insulation in the concrete face.

[0009] Another problem in the production of prefabricated insulated concrete elements is the many thicknesses in which the concrete elements are made. Each construction project has its own requirements with respect to the U value of the concrete elements and thereby the insulation thickness, as well as requirements concerning the selection between various types of insulation, where the λ value of the insulation determines the insulation thickness. This means that the concrete element factory must stock dowels in many different lengths in order to be able to make different concrete elements with different insulation layer thicknesses, so that they satisfy the requirements made with respect to the U value of the element in the individual construction projects.

[0010] However, it is a great wish to be able to manufacture an insulated concrete element, where the working processes to be performed in the manufacture may take place during the shortest possible time and with the fewest possible interruptions in the production, which e.g. the necessary drying times for concrete and other hardening materials normally involve.

The object of the invention

[0011] The present invention solves the above-mentioned drawbacks of the prior art and provides a dowel system and a method of attaching insulation to a concrete element, which make it possible to manufacture a prefabricated insulated concrete element such that all working processes may be performed during one working day. In addition, the invention ensures that the hardening of the concrete is thus no longer a restraint as to when the next steps in the finishing of the concrete element are to take place, and the hardening of the concrete layer in the concrete element may take place while the concrete element is being finished, as well as after completed mounting of insulation and optional application of an outer plaster coat to the insulation layer or coating of the surface of the insulation layer with a firm plate or other common types of coatings.

[0012] Moreover, it is the object of the invention to allow it to be watched during the attachment of the dowel system that the dowel system is secured correctly and also sufficiently safely in the face of the concrete elements, which contributes to ensuring that the carrying capacity of all the dowels in the manufactured concrete elements is far more uniform than the known insulation dowels or dowel systems allow.

Summary of the invention

[0013] This object is achieved by a method which comprises attaching the attachment parts of the dowel system around a reinforcement in a concrete face prior to the casting thereof, whereby the attachment parts are attached in the reinforced face and are held in a position in which they essentially protrude from the cast concrete face, placing the insulation material on the cast concrete face, whereby the attachment parts penetrate through the insulation material, mounting, on each of the attachment parts, a dowel head which has an anchoring disc and a pipe part with a through bore, said attachment part being passed through the bore, and pressing the pipe part down into the insulation material, so that the anchoring disc is essentially flush with the free surface thereof, and bending the attachment part around an anchoring face in a slot in the dowel head for holding the dowel head on the attachment part and thereby holding insulation material on the concrete element.

[0014] The above-mentioned object of the invention is also achieved by a dowel system, including a dowel head, for attaching insulation material to a concrete element, said attachment part comprising a wire in the form of an essentially rectilinear wire element having a hook part, said dowel head having an anchoring disc and a pipe part and having a through bore, through which bore the straight part of the wire member is inserted in connection with the attachment of the dowel head, said dowel head moreover having an opening in the form of a slot in the anchoring disc and the pipe part, said slot having a width which allows passage of the wire member.

[0015] In an embodiment of the method and the dowel system, including the dowel head, a pipe member is applied to the wire member, said pipe member being placed in the bore in the pipe part of the dowel head prior to the bending of the wire member. The pipe member is moved along out through the slot during the bending of the wire member over the anchoring face, thereby achieving a precise bending of the wire, which results in a uniform and sufficiently great stressing of the wire. This also ensures that the dowel head is held on the wire member, and that the insulation material is held on the concrete element with the desired strength.

[0016] Alternatively, a tool may be used for the bending of the wire member, which is capable of gripping a corresponding part of the wire member, so that the wire is bent precisely over the anchoring face, without using the pipe member. In that case, the gripping function of the tool must be designed so as to be easily released from the wire member after the wire member has been passed out through the slot and has been bent down into the insulation material.

[0017] In an embodiment of the method, the free end of the wire member is bent around the free end of the pipe member prior to the bending of the wire member and the accompanying pipe member over the anchoring face. Hereby, the wire member is stressed additionally, which additionally increases the strength of the attachment of the insulation on the concrete element.

[0018] In an embodiment of the method, an insulation strip is inserted into the opening which is produced in the insulation material after the bending of the wire member. This results in a considerable reduction of the risk that a thermal bridge occurs at the dowels.

[0019] It is preferred that the pipe part of the dowel head in the dowel system comprises a tapering part at the end of the pipe part which faces away from the anchoring disc. Hereby, the dowel head may easily be pressed down into the insulation material.

[0020] When the dowel head is provided with depressions and/or openings in the anchoring disc, it is ensured that a plaster coat, which is subsequently applied to the free surface of the insulation material, will also adhere to the dowel heads.

[0021] The above-mentioned advantages are moreover achieved by a use in which the dowel system according to the invention is used for attaching insulation material in the manufacture of insulated concrete elements.

Detailed description of the invention

[0022] The invention will now be described with reference to the drawing, in which

fig. 1a shows a dowel head for a dowel system according to the invention, seen in perspective,

fig. 1b shows a cross-section of a dowel head for the dowel system according to the invention,

fig. 1c shows a suitable attachment part in a dowel system according to the invention and the attachment thereof to the reinforcement in a concrete element,

fig. 2 shows a cross-section, where insulation, wire member, dowel head and pipe member are mounted,

fig. 3 shows the dowel system after the wire member has been shortened and bent the first time,

fig. 4 shows the dowel system after attachment of the wire member to the dowel head at bending out through a slot in the dowel head,

fig. 5 shows the dowel system after insertion of an insulation strip,

fig. 6a shows a tool for bending the outermost part of the wire member for holding the pipe member on the wire member,

fig. 6b shows another tool which grips the pipe member and bends this and the wire member,

fig. 6c shows the bending of the outermost end of the wire member, and fig. 6d shows the bending of the pipe and wire members for holding the dowel head on the wire member.

[0023] The dowel system essentially consists of three parts: A dowel head with an anchoring disc 1 and a pipe part 2, an attachment part, and a pipe member 8 which is mounted inside the pipe part 2 and around the attachment part.

[0024] The anchoring disc 1 of the dowel head and the pipe part 2 are preferably cast in one piece.

[0025] The attachment part comprises a wire member 7, which should have a hook part 7a capable of gripping the reinforcement to be cast into the concrete wall. The shape of the hook part is not essential, as it must merely be capable of gripping the reinforcement and should preferably protrude essentially perpendicularly upwards from the cast concrete face.

[0026] A suitable attachment part is shown in fig. 1c and comprises a straight wire member 7 having at its one end a hook part 7a, which is attached around the reinforcement A to be embedded in the reinforced face of the concrete element. Prior to the casting of the reinforced face, a plurality of attachment parts 7, corresponding to the necessary number of dowels, are thus attached to the reinforcement in a suitable even distribution across the entire area of the concrete element. Alternatively, the wire member 7 of the attachment part is mounted on the reinforcement in the concrete element by other well-known attachment techniques, which are used e.g. for the attachment of wall ties. After the attachment, the wire members 7 protrude essentially perpendicularly upwards from the wall of the concrete element, so that insulation 9 with the desired layer thickness may be pressed down over the vertical wire members 7 immediately after the casting of the reinforced face of the concrete element.

[0027] Since the attachment part of the dowel system, i.e. the wire member 7, is embedded in the reinforced face of the concrete element and is anchored to the reinforcement, it is ensured with great certainty that the carrying capacity of the dowels is well-defined and essentially constant for all the dowels. In addition, the positions of the dowels are constant and well-defined in all directions, i.e. both in a plane in parallel with the carrying face, perpendicularly thereto, and thus cannot rotate relative to the concrete element.

[0028] The wire member 7 has a length allowing it to be used for all thicknesses of the insulation layer 9, so that only a standard length of the wire member 7 is used. The diameter of the wire member 7 must give the dowel system sufficient strength to carry both the insulation layer 9 and a coating and/or plaster coat which is applied to the surface of the insulation layer 9. It has thus been found that wire thicknesses with a diameter between 2 and 6 mm, including preferably between 2.5 mm and 4.5 mm, it having been found that a diameter of about 3 mm is sufficient for most construction tasks. The wire members 7 are made of a material, preferably of metal, which withstands embedding in concrete and also possesses a suitable strength to carry insulation 9 and an optional coating or plaster coat, and is e.g. made of stainless steel.

[0029] The dowel head in the dowel system according to the invention is shown in perspective in fig. 1a, and has an anchoring disc 1 with a through opening 1' which is preferably disposed centrally on the anchoring disc 1, and a pipe part 2. A slot 3 extends in the pipe part 2 and in the anchoring disc 1, and the bottom of this slot 3 has a small elevation forming an anchoring face 4, whose function will be described below. The dowel head is made of a material, e.g. plastics or metal, with a suitable breaking strength. It is preferred that the dowel head is made of plastics, since this reduces the risk that a thermal bridge occurs in the area around the dowel head.

[0030] In an embodiment of the dowel system according to the invention, the anchoring disc 1 has a plurality of depressions and/or through openings 1", which are evenly distributed around the central opening 1'. These depressions and/or openings 1" ensure that an optional plaster coat will also adhere to the anchoring disc 1 itself, when it is applied to the surface of the insulation 9.

[0031] The pipe part 2 of the dowel head has an essentially cylindrical part 2' as well as a tapering part 2", and both the cylindrical part 2' and the tapering part 2" have an inner axially extending bore 5, 6. The central opening 1' of the anchoring disc is connected with the bore 5, 6 in the pipe part 2, and the centre point of the opening 1' in the anchoring disc 1 coincides with the axial centre line of the bore 5, 6 in the pipe part 2. The tapering end 2" ensures that the dowel head may be pressed down into the insulation material 9, so that the anchoring disc 1 is essentially flush with the surface of the insulation material 9.

[0032] The bore 6 in the tapering part 2" of the pipe part 2 preferably has a diameter which is slightly larger than the diameter of the wire member 7, and the bore 5 in the cylindrical part 2' of the pipe part 2 preferably has a diameter which is slightly larger than the pipe member 8.

[0033] The pipe member 8 has an inner diameter which is slightly larger than the diameter of the wire member 7, and the outer diameter of the pipe member 8 is slightly smaller than the width of the slot 4 in the anchoring disc 1 and the pipe part 2. The length of the pipe member 8 is larger than the length of the bore 5. When the pipe member 8 is inserted in the bore 5, the pipe member 8 will protrude a distance outside the dowel head, thereby making it possible to grip it with a tool, see figs. 6a and 6d. The pipe member 8 is made of a material which ensures that it cannot break when the wire and the pipe member are to be bent down into the insulation 9, and is e.g. made of metal, e.g. stainless steel, or, alternatively, of a suitable plastics material.

[0034] In fig. 1a, the anchoring disc 1 and the pipe part 2 are shown to be circular and circular-cylindrical, respectively, but are not restricted to this, as the cross-section of both the anchoring disc 1 and/or of the pipe part 2 may e.g. also be oval or polygonal, e.g. square, rectangular or hexagonal. Correspondingly, the tapering part 2" of the pipe part 2 may also assume the shape of a frustum of a cone with an oval cross-section or have the shape of a frustum of a pyramid with a polygonal cross-section.

[0035] The invention also relates to a method of attaching an insulation layer to a concrete element, using a dowel system according to the invention.

[0036] When a concrete element is to be produced, the casting of the carrying face of the concrete element is prepared by placing the reinforcement R in a mould/shuttering. Prior to the casting of the reinforced face in the concrete element, a suitable number of attachment parts are attached around the reinforcement R, said hook part 7a being mounted around the reinforcement R, e.g. as illustrated in fig. 1c.

[0037] Then the concrete face may be cast, and the wire members 7 then protrude essentially perpendicularly from, i.e. vertically up from, the surface of the cast face. Immediately after the casting of the concrete face, it is then possible to place the insulation 9 in the mould, as insulation plates 9 may be pressed down over the vertical wire members 7. Thus, it is no longer necessary to wait for the concrete to harden before the insulation is attached to the concrete element.

[0038] Then the dowel head 1 is applied, said axial bore 5, 6 through the dowel head 1 being passed down over the wire member 7, following which the pipe part 2' and the tapering part 2" thereof are pressed down into the insulation material 9.

[0039] Then the pipe member 8 is moved down around the wire member 7 and is placed in the bore 5 in the pipe part 2, as shown in fig. 2. As will be seen in fig. 2, the pipe member 8 protrudes from the bore 5 in the pipe part 2, which allows a tool B (see fig. 6b) to grip the pipe member, see figs. 6c-d. Then the wire member 7 is cut off, if necessary, at a suitable distance above the pipe member 8. The remaining wire member is then bent around the pipe member 8 with the tool A, as indicated by the arrows A' (fig. 6c), so that it forms a hook 7b or the like, e.g. as shown in figs. 3 and 6c. Hereby, the pipe member 8 is held on the wire member 7, and the tool A is removed, as indicated by the arrows A" and A"'.

[0040] To achieve stressing of the wire member 7 and thereby achieve holding of the dowel head on the wire member 7 and thus holding of the insulation 9 on the concrete element, the pipe member 8 and the accompanying wire member 7 are bent out through the slot 3 in the dowel head by tilting the tool B, as indicated by the arrows B' in fig. 6d, and subsequently pressed down into the surrounding insulation 9, as shown in fig. 4 and as illustrated in fig. 6d. To achieve the correct stressing of the wire member 7, the slot 3 in the dowel head is configured with an anchoring face 4 in the form of a projection at the bottom of the slot 3 of the pipe part, to ensure that the pipe member 8 and the accompanying wire member 7 bend exactly at the anchoring face 4 in the slot 3. Finally, the tool B is removed, as indicated by the arrows B" and B"' in fig. 6d.

[0041] The pipe member 8 may optionally be omitted, if, instead, a tool supporting the wire member 7 in the entire length of the bore 5 is used, so that the wire 7 bends precisely over the anchoring face 4 at the bottom of the slot, when the wire 7 is bent down into the surrounding insulation material 9.

[0042] The bending down into the insulation 9 thus ensures both the necessary stressing of the wire, which partly ensures holding of the dowel head on the wire member 7 and partly prevents the dowel head from rotating on the wire. This ensures the desired attachment of the insulation 9 on the concrete element, while simultaneously avoiding the occurrence of thermal bridges between the concrete face and the opposite side of the insulation 9 in the areas around the dowels.

[0043] When the wire member 7 is bent down, the anchoring disc 1 is pulled slightly down into the insulation material, so that the upper side face of the anchoring disc 1 is essentially flush with the upper side of the insulation, and at the same time the wire is stressed additionally.

[0044] To additionally reduce the risk of the occurrence of a thermal bridge at the dowels, an insulation strip 10, e.g. a piece of joint rear stop, may finally be placed in the resulting opening in the insulation 9, which is shown in fig. 5. Following this, the insulation 9 is mounted on the cast and still wet concrete element. At the same time as the concrete hardens, the surface of the concrete element may be finished, e.g. by the application of one or more plaster coats. The depressions and/or openings 1" of the anchoring disc 1 ensure that such plaster coats can also adhere to the anchoring disc 1. Thus, the method and the dowel system make it possible to manufacture an insulated concrete element, where the working processes to be performed in the manufacture may take place during the shortest possible time and with the fewest possible interruptions in the production.

[0045] The dowel system is particularly suitable for the attachment of the insulation materials in plate shape. Suitable insulation materials in this connection are particularly mineral wool, e.g. glass or rock wool, foam glass, plastics-based insulation materials, including polystyrene (PS), polyurethane (PU or PUR) or polyisocyanurate (PIR) and/or combinations thereof.

Claims

1. A method of attaching insulation material with a dowel system in the manufacture of a concrete element, said dowel system comprising an attachment part (7) and a dowel head (1, 2), characterized by comprising
attaching a plurality of attachment parts (7) around a reinforcement (R) in a concrete face prior to the casting thereof, whereby the attachment parts (7) are attached in the reinforced concrete face and are held in a position in which the attachment part (7) protrudes essentially perpendicularly from the cast concrete face,
placing the insulation material (9) on the cast concrete face, whereby the attachment parts (7) penetrate through the insulation material (9),
mounting, on each of the attachment parts (7), a dowel head (1, 2), which comprises an anchoring disc (1) and a pipe part (2) with a through bore (5, 6), said attachment part (7) being moved through the bore (5, 6), and pressing the pipe part (2) down into the insulation material (9) so that the anchoring disc (1) is essentially flush with the free surface thereof, and bending the attachment part (7) around an anchoring face (4) in a slot (3) in the dowel head (1, 2) for holding the dowel head on the attachment part (7) and thereby holding the insulation material (9) on the concrete element.

2. A method according to claim 1, characterized in that a pipe member (8) is applied to the attachment part (7), said pipe member being placed in the bore in the pipe part (2') prior to the bending of the attachment part (7), and that the pipe member (8) is moved along out through the slot (3) during the bending of the attachment part (7) over the anchoring face (4).

3. A method according to claim 2, characterized in that a free end of the attachment part (7) is bent (7b) around the free end of the pipe member (8) prior to the bending of the attachment part (7) and the accompanying pipe member (8) over the anchoring face (4).

4. A method according to any one of claims 1-3, characterized in that an insulation strip (10) is inserted into the opening which is produced in the insulation material (9) after the bending of the attachment part (7) and the possibly accompanying pipe member (8).

5. A dowel system for attaching insulation material to a concrete element, said dowel system comprising a dowel head and an attachment part, characterized in that the attachment part comprises a wire having an essentially rectilinear wire member (7) and a hook part (7a), and that the dowel head comprises an anchoring disc (1) and a pipe part (2) having a through bore (5, 6), through which bore (5, 6) the straight part of the wire member (7) is inserted in connection with the attachment of the dowel head, and that the dowel head moreover has an opening in the form of a slot (3) in the anchoring disc (1) and the pipe part (2), said slot (3) having a width which allows passage of the wire member (7).

6. A dowel system according to claim 5, characterized in that it moreover comprises a pipe member (8), which is placed around the wire member (7) in the bore (5) in connection with the attachment of the dowel system, and wherein the slot (3) has a width which also allows passage of the pipe member (8).

7. A dowel system according to claim 5 or 6, characterized in that the pipe part (2) comprises a tapering part (2") at the end of the pipe part (2) which faces away from the anchoring disc (1).

8. A dowel system according to claim 5, 6 or 7, characterized in that the anchoring disc (1) is provided with depressions and/or openings (1") in the anchoring disc (1).

9. A dowel head for attaching insulation material to a concrete element, characterized in that the dowel head comprises an anchoring disc (1) and a pipe part (2) having a through bore (5, 6), through which bore (5, 6) the straight part of the wire member (7) is inserted in connection with the attachment of the dowel head, and that the dowel head moreover has an opening in the form of a slot (3) in the anchoring disc (1) and the pipe part (2), said slot (3) having a width which allows passage of the wire member (7).

10. A dowel head according to claim 9, characterized in that the slot (3) has a width which also allows passage of a pipe member (8).

11. A dowel head according to claim 9 or 10, characterized in that the pipe part (2) comprises a tapering part (2") at the end of the pipe part (2) which faces away from the anchoring disc (1).

12. A dowel system according to claim 9, 10 or 11, characterized in that the anchoring disc (1) is provided with depressions and/or openings (1") in the anchoring disc (1).

13. Use of dowels according to any one of claims 5-8 or dowel heads according to any one of claims 9-12 in the manufacture of concrete elements for attaching insulation material (9) on the concrete elements.

Drawing