EP3284874A1

EP3284874A1 - Concrete anchor, concrete anchor system, and process for assembling a concrete anchor in a concrete element

Info

Publication number: EP3284874A1
Application number: EP16184879.1A
Authority: EP
Inventors: Tero Korhonen
Original assignee: SFS Intec Holding AG
Current assignee: SFS Group International AG
Priority date: 2016-08-19
Filing date: 2016-08-19
Publication date: 2018-02-21
Anticipated expiration: 2036-08-19
Also published as: DK3284874T3; PL3284874T3; LT3284874T; EP3284874B1

Abstract

A concrete anchor comprises a head-section (A), a shaft (B) defining a longitudinal axis (6) and a tip section (C). The anchor has essentially the cross-section of a thin-walled tube with a channel extending along its central axis. Shaft (B) exhibits an external thread with a thread height and a thread pitch construed to enable the anchor to selftap a thread in building insulation material.

Such an anchor is being used to in prefabricated concrete elements to secure insulation materials to the concrete body. To achieve this a mould for a concrete element is being provided, a concrete layer is poured into it and at least one layer of insulation material placed on the concrete layer. Then at least one concrete anchor according to the invention is screwed or driven through the insulation material layer into the concrete layer while the concrete has not yet fully hardened.

Description

The present invention refers to a useful concrete anchor, a concrete anchor system in the building industry. It is especially applicable for prefabricated concrete elements.

Background and Prior Art

In the building industry commonly prefabricated concrete elements are being used to allow for simplified and quick erection of buildings. Such prefabricated concrete elements include staircases, ceiling elements, floors, wall elements and others. Manufacturing them in controlled environments in high qualities, irrespective of weather and with specialized equipment helps lowering building cost and time on the construction site. It is of special advantage if not just a concrete element but a constructive element plus insulation, joining elements and other fittings such as piping and wiring can be provided.
Especially for outer wall elements insulation has become an essential and mandatory component to achieve statutory energy savings. In order to attach thermal insulation to a regular wall construction according to Prior Art, holes have to be drilled in the wall and concrete fasteners to be attached to allow for a secure connection between the wall and insulation. This requires a lot of hard manual work on site and includes creation of dust and noise. Such systems are named "External Thermal Insulation Composite Systems" (ETICS) or "Wärmedämmverbundsysteme" (WDVS) in German.
Moreover, modern insulation systems often combine layers of different functionality. Glass and mineral wool, foam glass, expanded polystyrene (EPS) or extruded polystyrene (XPS) are common materials to be used in layers. These materials exhibit different properties regarding size, weight, insulation capabilities, rigidity and toughness. Such layers have to be mounted on the concrete supporting structure, often in a compact arrangement. The numbers of fastening elements needs to be kept at a minimum for cost- and handling reasons.
Prefabricated concrete elements per se are known. Open molds, exhibiting the negative shape of a part to be manufactured are prepared with reinforcements such as armoring iron, sling points and other elements as required. Concrete is being added and allowed to cure and harden. Afterwards the prefabricated element is stripped from the formwork and stored until it is needed on the construction site.

Description of the invention

Consequently, it is an objective of the invention to provide a fixation element or concrete anchor allowing for safely and securely joining a concrete layer with one or more insulation layer without predrilling. Further, a method for manufacturing a concrete element and an anchoring arrangement is described with an anchor to be introduced in a concrete layer before or during hardening of the concrete and construed to allow for a secure joining of said concrete layer with one or more insulation layers.
The invention shall first be described in terms of the application of an anchor and afterwards the embodiments and features of the concrete anchor / fixation element shall be addressed.
Basically, the inventive process for assembling a concrete anchor in a concrete element comprises the following steps:

providing a mould,
providing a concrete layer in said mould
applying at least one layer of insulation material on the concrete while the concrete has not yet fully hardened or cured respectively
Screwing or driving at least one concrete anchor / fixation element according to the invention through the insulation material layer into the concrete layer
Stripping the concrete element including insulation from the formwork or mould after the hardening or curing process

In an embodiment of the invention, after screwing or driving the at least one concrete anchor / fixation element through the insulation material layer into the concrete layer a further layer of insulation material may be attached onto the at least one insulation layer utilizing the same concrete anchor.
In order to allow for this functionality, the concrete anchor has an inventive design hereinafter explained with the aid of Fig. 1. The concrete anchor 1 according to the present invention comprises a head-section A, a shaft B defining a longitudinal axis 6 and a tip section C with a closed tip 2. The anchor's basic geometry is a thin-walled tube with a channel 4 extending along said central axis 6. The shaft B has an external thread 3 with a thread height and a thread pitch chosen and construed to enable the anchor to self-tap a thread in building insulation material. Depending on the application, a man skilled in the art will chose an appropriate geometry. The thread here is shown located in a subsection B2 while a subsection B1 exhibits no thread. The relation between B1 and B2 depends on the technical properties of the first layer of insulation. A man skilled in the art will define the dimensions of the thread (i.e. the number of threads, pitch, height and thus the length required for B2) depending on the application profile.
Preferably said concrete anchor will have a structure or a texture at the tip section C which improves the pull-out resistance once the concrete has cured. The tip section C may exhibit at least one of or a combination of a thread section, a point-shaped tip, a corrugated surface, a protrusion, a recess, a slot, a groove, a roughened surface, each construed and able to be screwed or driven into uncured concrete. Depending of the predominant application a man skilled in the art will choose from this set of options or combine reasonably such features to allow for the desired functionality. With such an embodiment, the tip section of the anchor 1 will constitute a form-locked joint with the concrete after curing even without further mechanical means.
Due to the hollow, tube-like base structure of the anchor it is possible to use sections of said tube as counterparts for further fastening elements 9. An internal thread arranged at least partially on the sidewalls of the inner channel 6 (e.g. in sections B, C, both B and C, or parts of them) easily allows for screwing a screw into said channel. In case a self-tapping screw shall be used, this internal thread could be omitted. In the alternative, notches can be foreseen allowing for a simplified latching connection of fastener 9 and anchor 1 by simply driving the fastener into channel 4.
In a further preferred embodiment the head section A includes a spreading element 5. This spreading element leaves room for adjusting the length of the anchor to the desired sandwich of insulation layers. Such a spreading element represents a preferred embodiment because it will not require a cutting of individual anchors to a suitable length and thus reduce the variety of necessary models. It is being utilized by introducing a fastening element 9 into channel 4 (preferably with an intermediate joint 7 or plate element 8). The fastener will engage with the concrete anchor and drive joint 7 or plate element 8 towards the tip section C thus exerting force on the shaft which results in a forging of head section A in the foreseen part. Such a forging/spreading section can be e.g. realized by weakening the wall thickness of the shaft and thus introducing predetermined inflection points. The spreading part will thus allow compressing the insulation layer permanently in the mounted state.
A combination of a concrete anchor 1 as described above and a fastener 9 can be described as concrete anchor system. As addressed, the fastener may be a screw, a fixing element, a latching element or alike which corresponds with the anchor 1 accordingly. The fastener is introduced via the head section A and may engage with parts of shaft section B or tip section C. Since tip section C is firmly embedded after curing of the concrete, a fastener with a respective length will be able to provide a very strong support function.
An advantageous embodiment of a concrete anchor system includes a plate element 8 or a joint 7 arranged between the fastening element 9 and the concrete anchor 1. The plate element basically has the functionality of a washer, i.e. distributing surface pressure over a wider area. The fastener 9 will drive plate 8 closer to the surface of the uppermost insulation material and thus allow for a firmly locking of said material to the prefabricated concrete element. Given the washer-like nature of plate element 8, it will extend radially away from the central axis 6. The shape of the plate element 8 can be circular or any other appropriate shape. It may be made of plastic, sheet metal, light metal and may exhibit a flat, smooth outer surface (i.e. facing away from anchor 1). It may even offer further connecting elements like threads, holes, protrusions or alike, depending on the application profile.
Functionally, joint 7 serves a similar purpose like plate 8 (securing the uppermost insulation layer), however, in this specific embodiment joint 7 is designed to exert even a higher compressive force to the insulation layer. If fastener 9 is being tightened, joint 7 is being drawn into the layer. The wing-like design provides for a certain anti-torsion effect for the insulation layer. Preferably, joint 7 exhibits pins or cams on its outward-facing surface. This allows for attaching a mesh, net or textile web useful for reinforcing a protective and/or decorative render layer covering the insulation. It goes without saying that for this step the concrete is preferably cured already.
Depending on the application profile the joint 7 or plate element 8 will show different designs to fulfill the desired purpose. In case of a firm connection, even further mounting elements or sub-constructions (battens) may be attachable as well as façade-elements.
The term "concrete" as used herein, shall include all variants of such construction material suitable to be processed in a fluid or semi-fluid state and to be hardened or cured afterwards. The curing or hardening may be achieved by chemical/physical reactions or irradiation, illumination or thermal exposure as the case may be.
As mentioned before, using a mould in a concrete factory to fabricate a concrete element has several advantages. The surface of the mould can be prepared seamless, clean and smooth; it can be arranged ideally for pouring the concrete. Armoring iron can be arranged into the mould as required and environmental conditions can be controlled to achieve a perfect curing or hardening effect. According to the inventive process after the initial pouring of concrete at least a first layer of insulation is arranged atop the surface of the concrete. Preferable an insulation material is being chosen that does not absorb moisture from the concrete and has certain rigidity. This first layer may be arranged covering the full surface of the concrete or just parts of it, leaving e.g. edges or cut-outs free if necessary.
Then a concrete anchor is screwed or driven through the insulation layer into the concrete, which is still wet or has not yet fully hardened. The concrete anchor preferably exhibits at least one threaded section on its shaft allowing for tightly linking the insulation element with the concrete. Since the concrete is still in a tough-flowing or viscous state, no pre-drilling is required; the concrete anchor is joining with the concrete in its tip region; consequently after curing the concrete anchor is permanently fixed.
In another embodiment, the anchor has a shaft with a length dimensioned to allow for applying a further layer of insulation to be fixed using the same concrete anchor. For this purpose the anchor may have a residual section protruding from the first layer of insulation. The further or e.g. second layer of insulation is simply impressed on top of the first layer, the residual section of the anchor simply displaces the insulation material where necessary and thus fixates the second (or further) layer to the first layer. The residual section of the anchor's shaft may exhibit means like a thread or notches, suitable for connecting with a head screw, a top plate or another element adapted to increase the bond between the insulation layers. This element may further exhibit means like holes, hooks, clasps or alike to e.g. allow for connecting a façade element or a sub-construction for the face of the building or to facilitate applying layers of render.
The elements and features described herein (in the description and in the claims) shall be understood as combinable to the extent as technically reasonable and/or desirable.

Short description of the figures

Fig. 1 shows a concrete anchor according to the main embodiment of the invention
Fig. 2a shows a concrete anchor with a sharp tip section incl. thread portion
Fig. 2b shows the anchor of Fig. 2a with a joint 7 mounted
Fig. 3 shows a concrete anchor with an alternative tube-like tip-section C
Fig. 4 shows a plate element 8 in top and side view plus a fastener 9
Fig. 5a-g show the steps of the inventive process for assembling a concrete anchor in a concrete element

Detailed explanation of the figures

Fig. 1 shows a concrete anchor 1 in one basic embodiment with a tip 2, a thread 3 in shaft section B2. The tip section C exhibits a corrugated structure intended to enhance the pull-out forces in a mounted state. Reference 4 marks the channel along the central axis 6, construed to accept a fastener 9 (not shown). The functionality has been addressed above in detail.
Fig. 2a shows a concrete anchor according to an embodiment of the invention with a sharp tip in section C and a short thread portion adjacent to the tip. This short tip thread is intended to facilitate the entry of the anchor into the insulation layer. the sharp-edged tip will facilitate displacing the insulation material.
Fig. 2b shows the anchor of Fig. 2a with a joint 7 mounted such that spreading element 5 is engaged. The spreading element shown has a telescopic design, however this is not mandatory or limiting. The fastener required to achieve the actuation of spreading element 5 has been omitted. The functionality has been described above in detail.
Fig. 3 shows a concrete anchor according to an embodiment of the invention tube-like tip-section C. When using a smooth outer surface, this tip section C will itself provide less grip in the concrete, however, it will act as a dowel when later a fastening element is inserted into the channel extending along the central axis. In the alternative such a tip section C can be equipped with a roughened surface allowing for improved grip in concrete.
Fig. 4 shows a plate element 8 in top and side view plus a fastener 9. Top plate 8 here shows a recess for fastener 9 to allow for a flush surface when mounted.
Fig. 5a-g show the steps of the inventive process for assembling a concrete anchor in a concrete element. Figure 5a shows a mould 10 in an exemplary display and shall not be understood as limiting to the invention; the mould may be of any shape technically feasible and reasonable. Fig. 5b shows the mould 10 partially filled with concrete 11. In Fig. 5c a first layer of insulation 12 has been added. This insulation may be available in plate shape (EPS, XPS), in roles or mats. For the core of the invention it is not important if the insulation layer is covering the whole area of the concrete surface or not. It is also not required that an even layer of insulation is provided, this may vary according to constructive needs.
Fig. 5d shows the stack of concrete 11 and first layer of insulation 12 with a concrete anchor 1 in place. The anchor does not penetrate the concrete layer completely and thius remains invisible later from the concrete side (here bottom of stack). Shaft section B is covered in the first layer of insulation. A sort part, alter identified with spreading element 7 is still visible.
Fig. 5e shows an embodiment of the invention where a further insulation layer 13 has been added (stacked) on top. This may be advantageous if additional insulation of different type is required. This step can be performed while the concrete is hardening or later, after is has cured.
Figure 5f shows the state of Fig. 5e with joint 7 ready for being applied to the concrete anchor 1. This step preferably takes place when the concrete has cured to avoid the concrete anchor being displaced (pulled out) by the forces while tightening the fastener.
Figure 5g shows the final state of the embodiment of Fig. 5f. The joint 7 has been driven into the upper insulation layer 13, thus providing a flush surface of the prefabricated concrete element.

Reference numerals

1: concrete anchor, fixation element
2: tip
3: external thread
4: (axially extending) channel
5: spreading element
6: central, longitudinal axis
7: joint
8: plate element
9: fastening element
10: mould
11: concrete layer
12: (first) layer of insulation
13: further / second layer of insulation

A: head section
B: shaft
C: tip section

Claims

A concrete anchor (1) comprising a head-section (A), a shaft (B) defining a longitudinal axis (6) and a tip section (C) with a closed tip (2), the anchor (1) essentially having the cross-section of a thin-walled tube with a channel (4) extending along said axis (6) wherein the shaft (B) exhibits an external thread (3) with a thread height and a thread pitch construed to enable the anchor to self-tap a thread in building insulation material.
A concrete anchor according to claim 1, wherein the tip section (C) exhibits at least one of or a combination of a thread section, a point-shaped tip, a corrugated surface, a protrusion, a recess, a slot, a groove, a roughened surface, each construed to be screwed or driven into uncured concrete.
A concrete anchor according to claim 1-2, wherein the tip section (C) constitutes a form-locked joint with the concrete after curing.
A concrete anchor according to claim 1-3, wherein the head section (A) includes a spreading element (5).
A concrete anchor according to claim 1-4, wherein the axially extending channel (4) exhibits at least in its tip section (C) an internal thread.
A concrete anchor according to claim 1-5 made from plastic, preferably polyamide or light metal such as aluminum.
A concrete anchor system comprising a concrete anchor (1) according to the preceding claims and a fastening element (9), which can be introduced into the concrete anchor's channel (4) via the head section (A).
A concrete anchor system according to claim 7, wherein the fastening element (9) engages with the internal thread of tip section (C).
A concrete anchor system according to claim 7-8, characterized in that a plate element (8) can be arranged between the fastening element (9) and the concrete anchor (1) such that the plate of the plate element extends radially away from the central axis (6).
A concrete anchor system according to claim 7-8, characterized in that a joint (7) can be arranged between the fastening element (9) and the concrete anchor (1) such that the joint, when installed, is securing the outermost insulation layer and at the same time provides a mounting interface for further constructive elements such as a sub-construction, a façade, render or alike.
A concrete anchor system according to claim 9 or 10, wherein joint (7) or plate element (8) are made from metal such as steel or from plastic.
A concrete anchor system according to claim 7-11, characterized in that the fastening element (9), while being installed, forces joint (7) or plate element (8) towards tip section (C) thereby forging head section (A) and spreading spreading element (7).
A process for assembling a concrete anchor (1) in a concrete element comprises the following steps:
- providing a mould (10),

- providing a concrete layer (11) in said mould (10)

- applying at least one layer of insulation material (12) on the concrete layer (11) while the concrete has not yet fully hardened

- Screwing or driving at least one concrete anchor (1) according to claims 1-6 through the insulation material layer (12) into the concrete layer (11)

- Stripping the concrete element including insulation from the formwork or mould after the hardening or curing process
A process according to claim 13, further comprising introducing a fastening element (9) into channel (4) of concrete anchor (1) via head section (A).
A process according to claim 13-14, further comprising arranging a joint (7) or plate element (8) between fastening element (9) and concrete anchor (1).
A process according to claim 13-15, wherein the fastening element (9) is being screwed or driven into anchor (1) thus forcing joint (7) or plate element (8) towards tip section (C) and forging head section (A) by spreading spreading element (7).