WOOD-CONCRETE COMPOSITE ELEMENT AND METHOD FOR ITS MANUFACTURING

Description

[0001] The invention relates to a wood-concrete composite element according to the preamble of claim 1 and a method for producing the wood-concrete composite element according to claim 10.

[0002] German patent DE 102 54 043 B4 discloses a method for producing a wood-concrete composite element in which beams of a wooden component are encased in concrete during the production of a concrete slab, thereby creating a connection between the wood and the concrete component.

[0003] European Patent EP 2 787 140 B1 discloses a method for manufacturing a flat ceiling in which a concrete slab is bonded to a wooden slab by adhesive. For this purpose, spacers are placed between the two unbonded slabs, and the resulting gap between them is filled with adhesive. However, filling the gap with adhesive requires openings in the slab that is on top during bonding, both to allow the adhesive to be poured into the gap and / or to monitor the pouring process. Creating these openings and any subsequent sealing are complex steps that increase the cost of manufacturing the flat ceiling.

[0004] Document EP 3 868 970 A1 discloses a wood-concrete composite element according to the preamble of claim 1.

[0005] The object of the invention is therefore to provide an alternative wood-concrete composite element that can be manufactured more easily and cost-effectively.

[0006] This problem is solved according to the invention by a wood-concrete composite element with the features of claim 1 and by a method for producing a wood-concrete composite element according to claim 10.

[0007] The wood-concrete composite element according to the invention comprises a concrete component and at least one wood component, which are bonded together by means of an adhesive.

[0008] The concrete component is, in particular, a concrete slab, especially made of reinforced or prestressed concrete, and especially a concrete ceiling. "Slab" refers to a component whose width and length are many times greater than its thickness, for example, by a factor of at least 8 to 10.

[0009] The wooden component is, in particular, a wooden beam. "Beam" refers to a component whose length is many times greater than its width and height, especially by a factor of 8 to 10. Specifically, the height of the beam is at least equal to its width, and in particular greater.

[0010] The concrete and timber components are bonded together with adhesive to form a composite wood element, which may also include other components. The bonding is applied over a large area. Specifically, at least 20%, at least 50%, and at least 90% of the surface area of ​​the timber component facing the concrete component, hereinafter referred to as the "underside," is covered with adhesive.

[0011] A characteristic feature of the wood-concrete composite element according to the invention is that the concrete component has a recess in which the wood component is arranged. The adhesive, which bonds the two components to form the composite element, is arranged between the wood component and the concrete component.

[0012] The recess extends into the concrete component in the direction of its depth. The recess is located, in particular, on a flat outer surface. This outer surface extends, in particular, in the direction of the width and length of the concrete component, while the depth of the recess extends, in particular, in the direction of the thickness of the concrete component. The outer surface is hereinafter also referred to as the "top" of the concrete component. The recess extends into the concrete component to a base and is designed such that it can at least partially, and in particular completely, accommodate the underside of the wooden component. The base of the recess forms, in particular, a flat surface that is parallel to the outer surface.

[0013] After bonding with the adhesive, the wooden component lies at least partially, and in particular completely, within the recess on its underside. The material-bonded connection is formed primarily via the surfaces of the wooden component's underside that lie within the recess.

[0014] The depression is in particular a groove which has a rectangular or a trapezoidal cross-section that widens outwards from the base of the groove, i.e. the bottom of the depression.

[0015] The adhesive is, in particular, an epoxy resin, specifically a multi-component system, that exhibits sufficient bond strength to wood and concrete to meet the respective structural requirements. Specifically, the adhesive has a sufficiently low viscosity to allow it to flow independently into the recess and, if necessary, into a gap of a few millimeters between the wood and concrete components.

[0016] Preferably, the depth of the recess is less than the height of the wooden component. The height of the wooden component is measured in the same direction as the depth of the recess. Thus, after gluing, the wooden component protrudes from the recess beyond the concrete component, particularly beyond a flat outer surface.

[0017] Preferably, the width of the recess is greater than that of the wooden component and / or the length of the recess is greater than the length of the wooden component. The width of the recess is measured in the direction of the width of the wooden component, and the length of the recess in the direction of the length of the wooden component. In particular, the length of the recess is shorter than the length of the concrete component measured in the same direction and / or the width of the recess is less than the width of the concrete component measured in the same direction, so that the recess has lateral edges that enclose the recess on all sides.

[0018] The recess is designed in such a way that it can completely accommodate the base of a cuboid that circumscribes the wooden component. Specifically, the recess is a groove whose base has a length and width greater than the length and width of the underside of the wooden component.

[0019] Furthermore, it is preferred that the adhesive is arranged in the recess. In particular, the adhesive is arranged exclusively in the recess so that, when the wooden component is bonded to the concrete component as planned, it is located exclusively in the recess and no other area of ​​the concrete component is covered with adhesive for bonding to the wooden component.

[0020] In a preferred embodiment of the wood-concrete composite element according to the invention, the contact area between the adhesive and the concrete component is larger than the contact area between the wood component and the adhesive. This ensures a good bond between the wood component and the concrete component.

[0021] Preferably, the maximum thickness of the cured adhesive after bonding, i.e., once the adhesive has cured, is less than the depth of the recess, with the thickness of the adhesive layer and the depth of the recess being measured in the same direction. This lesser thickness of the adhesive layer than the depth of the recess, when the recess is appropriately positioned during bonding, prevents adhesive from oozing out of the recess and becoming unavailable for bonding, which would otherwise require a larger quantity of adhesive to bond the wooden component to the concrete component.

[0022] According to the invention, at least one spacer is arranged between the concrete component and the wooden component. The spacer prevents the wooden component from directly contacting the concrete component in the area of ​​the spacer. In particular, several spacers are arranged between the wooden and the concrete component, especially at specific points, such that the wooden component is not in direct contact with the bottom of the recess. For this purpose, the spacer is arranged, in particular, between the bottom of the recess and the underside of the wooden component. The spacer prevents the wooden component from lying flat against the concrete component, so that no adhesive can get between the wooden and the concrete component during bonding, or so that the adhesive, if already present in the recess before the wooden component is inserted, would not be completely displaced from the area between the underside of the wooden component and the bottom of the recess.The spacer can be, for example, a cylinder, a sphere, or a ring, such as a standard washer. The spacer can also be permanently attached to the concrete component and / or the wooden component. For instance, the spacer can be formed by the head of a screw driven into the wooden component to a certain depth. The spacer can also be integral with the wooden component and / or the concrete component, for example, by milling and leaving in place a rib or ribs or individual studs on the wooden component, which then form one or more spacers. The milled areas of the wooden component between these ribs then form the underside. It is also possible to incorporate spacers manufactured together with the concrete component in the recess, particularly at the bottom of the recess. These spacers can be shaped, for example, as cuboids, ribs, or frustoconical studs.The thickness of a spacer is in particular 1 to 5 millimeters, in particular 2 to 3 millimeters, which corresponds to the mean thickness of the adhesive layer between the bottom of the recess and the underside of the wooden component after gluing.

[0023] In particular, the adhesive is positioned along the edge of the underside of the wooden component in such a way that it covers the side adjacent to the underside at the transition to the underside. This means that the adhesive is positioned higher in the recess outside the gap than within the gap itself. The maximum thickness of the adhesive is therefore greater than the height of the spacer, but, more importantly, less than the depth of the recess. This has the advantage that, when the adhesive is still sufficiently fluid, it is forced into the gap and fills it simply by static pressure, without the need for complex checks or gluing procedures.

[0024] It is further preferred that the concrete component has several recesses. Several recesses can be provided for bonding a wooden component to the concrete component, wherein, in particular, areas of the wooden component between the areas that engage in the recesses are milled out to allow engagement. Preferably, at least one, and in particular exactly one, wooden component is arranged in each recess. In particular, the wooden component is a wooden beam arranged in exactly one recess.

[0025] The concrete component is preferably a precast concrete element in which the recess is already formed during the manufacturing process. Concrete spacers, which are integral with the concrete component, can also be produced during manufacturing, for example, by means of corresponding shapes in the formwork.

[0026] In particular, the wooden component in the installed position of the wood-concrete composite element in a building forms a beam, while the concrete component forms a ceiling above.

[0027] The inventive method for producing a wood-concrete composite element, as described above, comprises at least the following four steps: a) Production of the concrete component with at least one recess: In particular, production is carried out as a precast concrete element. Specifically, the recess or recesses are already incorporated into the concrete component during production, for example, by arranging one or more corresponding inserts on the formwork. The inserts form a negative of the desired recess and are removed from the concrete component along with the formwork after concreting. Alternatively, the recess can be subsequently formed on the concrete component by milling or similar methods that locally remove concrete. b) Placement of at least one spacer in the recess: After the recess has been created, a spacer can be placed in the recess. Additionally, or alternatively, spacers can also be placed in the recess during the production of the concrete component.A spacer can, for example, be embedded in the concrete component as an insert, such that it protrudes above the bottom of the recess by the desired distance. Alternatively, or in addition, a spacer can be attached to the wooden component. c) Applying adhesive to the recess: The adhesive can be applied to the recess after it has been created and before the wooden component is placed on it in step d), whereby the adhesive does not completely fill the recess. This has the advantage that the adhesive can be applied very easily by brushing, spreading, pouring, or similar methods. Alternatively, or in addition, the adhesive can be applied after the wooden component has been placed in the recess or after the wooden component has been placed on the spacers.For pouring and filling the gap created by the spacer between the concrete and the wooden component, the adhesive has a sufficiently low viscosity so that it can be poured in liquid form and fill even relatively narrow gaps through flow or static pressure alone. The side of the concrete component with the recesses is primarily facing upwards when the adhesive is applied, so that the adhesive moves into the recess and between the wooden and concrete components, or remains there, simply due to gravity. d) Placing the wooden component onto one or more spacers: The wooden component can be placed onto the spacer before or after the adhesive has been applied.

[0028] Preferably, step c) of the method is carried out according to step d). In this case, the wooden component is already in the recess and is placed on at least one spacer, in particular on several spacers, so that the adhesive is subsequently applied and the bond between the wooden and concrete components is created. For this purpose, adhesive is applied in a sufficient quantity to fill the gap, in particular in such a quantity that the adhesive level is higher on the sides of the wooden component in the recess than in the gap under the wooden component.

[0029] Alternatively, step c) can be performed before step d). In this case, the adhesive is first applied to the recess, then the wooden component is placed onto one or more spacers.

[0030] The spacer can be positioned in the recess according to step b) during the preparation of the recess according to step a), particularly when casting a precast concrete element using an insert; after the preparation of the recess according to step a), particularly by inserting, for example, washers of appropriate thickness into the recess; or during the application of adhesive into the recess, but then before step d). Positioning one or more spacers during the application of the adhesive into the recess is achieved, for example, by mixing spacers into the adhesive, for instance, in the form of spheres or particles with appropriate diameters. In this case, the spacers are distributed in the adhesive and are filled into the recess along with the adhesive.

[0031] To prevent adhesive from leaking out of the recess, for example, if the recess extends over the entire length of the concrete component, a sealing element can be placed in or on the recess before step c). The sealing element prevents the adhesive from flowing out of the recess and / or limits the area of ​​the recess where the adhesive is applied, so that only the amount of adhesive actually required for load transfer needs to be placed in the recess. The sealing element can be, for example, a strip made of rubber, plastic, wood, or a similar material. Alternatively, a hardening sealant, such as construction silicone or a construction adhesive, can be used, which is dispensed as a bead from a cartridge and applied to the concrete component.

[0032] The invention is explained in more detail below with reference to several exemplary embodiments shown in the drawing.

[0033] They show: Figures 1 to 5 show the production of a wood-concrete composite element according to the invention according to a first method; Figures 6 to 9 show the production of the wood-concrete composite element according to the invention according to a second method; Figures 10 to 12 show the production of the wood-concrete composite element according to the invention according to a third method; and Figures 13 to 15 show three wood-concrete composite elements according to the invention, each in a top view.

[0034] In the Figures 1 to 5 The production of a wood-concrete composite element 1 according to a first method according to the invention is illustrated. The Figure 5The illustrated wood-concrete composite element 1 consists of a concrete component 2, here a reinforced concrete slab, which has a thickness DB in the image plane, a width BB orthogonal to it in the image plane, and a length LB orthogonal to the thickness DB and to the width BB ( Figure 1 In the exemplary embodiment, the length LB is 6.40 meters, the width BB is 1.5 meters, and the thickness DB is 8 centimeters. The concrete component 2 is a precast concrete element that was manufactured in a first process step in a precast concrete plant with a recess 3 created during concreting by means of an insert arranged on the formwork (not shown). Figure 1The concrete component 2 is visible after formwork removal. The recess 3 is located on an outer surface of the concrete component 2 and extends from a top surface 4 of the concrete component 2 into the concrete component 2, or rather, it recesses the concrete component 2 in the area of ​​the recess 3. In the plane of the image, the recess 3 has a cross-section in the shape of an isosceles trapezoid, which widens from a rectangular, flat base 5 of the recess 3 outwards towards the top surface 4 in its width BV. The recess 3 has a constant depth TV of 1.5 centimeters from the base 5 to the top surface 4. In this embodiment, the width BV of the recess 3 is 20 centimeters at the base 5 and 23 centimeters at the top surface 4. The recess 3 extends over the entire length LB of the concrete component 2 and has a length LV of 6.40 meters, which also means that it is open at its ends 8.

[0035] The next step, which involves Figure 2As shown, spacers 6 are arranged in the recess 3, in this embodiment on the flat base 5. In this embodiment, the spacers 6 are cylindrical plastic bodies with a height HA of 2 millimeters and a diameter of 8 millimeters. Thus, the height HA of the spacers 6 is less than the depth TV of the recess 3.

[0036] As this is in Figure 3As shown, in the following step a wooden component 7, in this embodiment a wooden beam, is placed onto the spacers 6 such that a gap 17 exists between the concrete component 2 and a bottom surface 16 of the wooden component 7, the height HS of which corresponds to the height HA of the spacers 6. The depth TV of the recess 3 is less than the height HH of the wooden component 7, so that the wooden component 7 projects beyond the recess 3 and thus also beyond the top surface 4 of the concrete component 2. Furthermore, the width BV of the recess 3 is greater than the width BH of the wooden component 7, which allows adhesive 14 to be introduced into the recess 3 in a subsequent step even after the wooden component 7 has been inserted into the recess 3, without, for example, the need for openings in the wooden component 7 for filling the adhesive 14. In this embodiment, the wooden component 7 has a width BH of 16 centimeters and a height HH of 24 centimeters.The length LH is also 6.40 meters.

[0037] Since the recess 3 is open at its ends 8, before the next step, the filling of the adhesive 14 into the recess 3, the recess 3 is sealed at its ends 8 with a thick bead of sealant as a sealing element 9, as shown in Figure 13 is shown. Figure 14 The case is shown in which a shorter wooden component 7 is used, and the recess 3 is arranged centrally in the concrete component 2, such that the recess 3 is completely surrounded by an edge 10, i.e., not only at the longitudinal edges 11 as in Figure 13 , but also at end edges 12. The recess 3 is a few centimeters longer than the wooden component 7. Additional sealing is generally not necessary in this case, unless the wooden component 7 is only to be bonded to the concrete component 2 in certain, locally limited areas 13 of the recess 3, as is the case here. Figure 15 shows.

[0038] In the next step, which is in Figure 4 As shown, adhesive 14 is introduced into the recess 3, for example, by a processor pouring it from a bucket 15 into the recess 3. Here, the adhesive 14 is a low-viscosity epoxy resin that is so fluid that it spreads evenly throughout the recess 3 under its own static pressure and completely fills the gap 17. The adhesive 14 is located exclusively in the recess 3. In the area of ​​the gap 17, the thickness DKS of the cured adhesive 14 corresponds to the height HS of the gap 16 or the height HA of the spacers 6. In the exemplary embodiment, the thickness DKM of the adhesive 14 is greater on the side of the wooden component 7 after pouring and curing, and the adhesive 14 also rests against the side of the wooden component 7. Figure 5The maximum thickness DKM of the cured adhesive 14 is not as large as the depth of the depression 3. Therefore, the adhesive 14 does not reach the top surface 4 of the concrete component 2. The contact area between the adhesive 14 and the concrete component 2 is larger than the contact area between the wooden component 7 and the adhesive 14.

[0039] After the adhesive 14 has hardened, the wood-concrete composite element 1 is finished, which Figure 5 shows, and can be incorporated into a building (not shown).

[0040] The Figures 6 to 9 and 10 to 12 Two alternative methods for manufacturing a wood-concrete composite element 1 according to the invention are shown. To avoid repetition, only the differences from the method described above are discussed below. The same reference numerals are used for identical components.

[0041] The two methods differ from the one described in the Figures 1 to 5The method described is achieved by introducing the adhesive 14 into the recess 3 in front of the wooden component 7.

[0042] In the Figures 6 to 9 In the described procedure, after the spacers 6 have been inserted into the recess 3, the adhesive 14 is applied to the recess 3. In this case, the adhesive 14 can be more viscous and can, for example, be dispensed by the user from a cartridge 18. After the adhesive 14 has been applied, it can be spread in the recess, for example, with a spatula. It is advantageous if the spacers 6 are firmly attached to the concrete component 2 to prevent them from being moved along with the adhesive 14 when it is spread with the spatula. Since a low-viscosity adhesive is not required in this case, the selection of a suitable adhesive 14 is simplified.

[0043] In the Figures 10 to 12In the described method, the spacers 6, which are steel balls with a diameter of 2 millimeters, are added to the adhesive 14, so that the spacers 6 together with the adhesive 14 are placed into the recess 3, thus simplifying the process and eliminating one step. After the adhesive 14 has been applied, the wooden component 7 is again placed into the recess 3 and thus positioned onto the spacers 6.

[0044] Regardless of the chosen method, several, in particular parallel, recesses 3 can be provided on a concrete component 2 and a wooden component 7 can be glued into each recess 3 using adhesive 14. Reference symbol list Wood-concrete composite element and method for its manufacture

[0045] 1 Wood-concrete composite element 2 Concrete component 3 Recess 4 Top of concrete component 2 5 Bottom of recess 3 6 Spacer 7 Wood component 8 End of recess 3 9 Sealing element 10 Edge of recess 3 11 Longitudinal edge of recess 3 12 End edge of recess 3 13 Partial area of ​​recess 3 14 Adhesive 15 Bucket 16 Bottom of wood component 7 17 Gap 18 Cartridge DB Thickness of the concrete component 2 BB Width of the concrete component 2 L Length of the concrete component 2 TV Depth of the depression 3 BVB Width of the depression 3 LV Length of the depression 3 HAH Height of spacer 6 DA Diameter of spacer 6 HHH Height of the wooden component 7 BH Width of the wooden component 7 LHL Length of the wooden component 7 HSH Height of the gap 17 DKS Thickness of the cured adhesive 14 in the gap 17 DKM Maximum thickness of the cured adhesive 14

Claims

1. Wood-concrete composite element (1) comprising a concrete element (2), in particular a concrete ceiling, and at least one wooden element (7), in particular a beam, which are connected to each other by means of an adhesive (14), wherein the concrete element (2) has a recess (3) in which the wooden element (7) is arranged, characterized in that at least one spacer (6) is arranged between the concrete element (2) and the wooden element (7), the height (HA) of which is less than the depth (TV) of the recess (3), and / or that at least one spacer (6) is formed on the concrete element (2) in the recess (3), the height (HA) of which is less than the depth (TV) of the recess (3).

2. Wood-concrete composite element (1) according to claim 1, characterized in that the depth (TV) of the recess (3) is less than the height (HH) of the wooden element (7).

3. Wood-concrete composite element (1) according to one of the preceding claims, characterized in that the width (BV) of the recess (3) is greater than the width (BH) of the wooden element (7) and / or that the length (LV) of the recess (3) is greater than the length (LH) of the wooden element (7).

4. Wood-concrete composite element (1) according to one of the preceding claims, characterized in that the adhesive (14) is arranged in the recess (3), in particular exclusively.

5. Wood-concrete composite element (1) according to one of the preceding claims, characterized in that a contact area between the adhesive (14) and the concrete element (2) is larger than a contact area between the wooden element (7) and the adhesive (14).

6. Wood-concrete composite element (1) according to one of the preceding claims, characterized in that the maximum thickness (DKM) of the cured adhesive (14) is less than the depth (TV) of the recess (3).

7. Wood-concrete composite element (1) according to one of the preceding claims, characterized in that the concrete element (2) has several recesses (3).

8. Wood-concrete composite element (1) according to claim 7, characterized in that a wooden element (7) is arranged in each recess (3).

9. Wood-concrete composite element (1) according to one of the preceding claims, characterized in that the concrete element (2) is a precast concrete element.

10. Method for manufacturing the wood-concrete composite element (1) according to one of the preceding claims, comprising the following steps: a) manufacturing the concrete element (2) with at least one recess (3) b) arranging at least one spacer (6) in the recess (3), the height (HA) of which is less than the depth (TV) of the recess (3) c) inserting adhesive (14) into the recess (3) d) placing the wooden element (7) on one or more spacers (6)11. Method according to claim 10, characterized in that step c) follows step d).

12. Method according to claim 10, characterized in that step c) is performed before step d).

13. Method according to one of claims 10 to 12, characterized in that step b) is performed with step a) or step b) is performed after step a) or step b) is performed with step c).

14. Method according to one of claims 10 to 13, characterized in that, before step c), a sealing element (9) is arranged in or on the recess (3) in such a way that the sealing element (9) prevents the adhesive (14) from flowing out of the recess (3) and / or limits a portion (13) of the recess (3) in which the adhesive (14) is arranged in the recess (3).