A prefabricated reinforcing skeletal framework and a method for construction of reinforced concrete structures

Abstract

The invention relates to a prefabricated erectable reinforcing skeletal framework (10), for the construction of reinforced concrete structures, wherein the reinforcing skeletal framework (10) comprises at least two mesh layers, namely a first mesh layer (11) and a second mesh layer (12), and several spaced apart spacers (13) 5 connecting said two layers (11, 12), wherein each spacer (13) is pivotally connected to the first mesh layer (11) in a first connection point (21) and wherein each spacer (13) is pivotally connected to the second mesh layer (12) in a second connection point (22), each spacer (13) is pivotable around substantially parallel axes passing through the first and the second connection points (21, 22). The invention also 0 relates to a method for casting a reinforced concrete slab using a prefabricated erectable reinforcing skeletal framework.

Description

[0001] A prefabricated reinforcing skeletal framework and a method for construction of reinforced concrete structures

[0002] Field of the invention

[0003] The invention relates to a prefabricated reinforcing skeletal framework that is foldable and erectable, for the construction of reinforced concrete structures.

[0004] Background of the invention

[0005] Reinforced concrete is widely used in many different types of structures and components of structures such as slabs, walls, floors, foundations, beams and for civil engineering projects such as for bridges, dams and so on. Most reinforced concrete structures comprise a reinforcing skeletal framework usually a steel framework.

[0006] Reinforcing steel bars where traditionally assembled into a framework on the building structure and then concrete is poured around the framework to form a floor or wall, for example. Constructing the reinforcing framework on site is relatively time consuming and generally skilled steel workers are required. Lately it has become more common to prefabricate the reinforcing framework in modules off site in a factory or similar facility, and then transport the reinforcing framework to the building site in modules.

[0007] In a floor slab, the reinforcing framework typically comprises two layers comprising rebar arranged and fixed in a mesh pattern. The mesh layers are usually arranged with a distance between them of typically 100 - 500 mm (in the Norwegian marked) depending on the thickness of the floor. However, the system according to the invention can easily cover more than 1000 mm. A prefabricated reinforcing skeletal framework for such a floor slab will then have quite a large volume which is a drawback when it comes to transportation. A truck or trailer will be filled up without coming close to the weight limitation of the truck or trailer.

[0008] Transporting such prefabricated reinforcing framework modules is therefore quite costly and the carbon footprint increases drastically as a result of the transport.

[0009] JP H0625419 II discloses a reinforcing steel cage that is foldable. The reinforcing steel cage comprises two mesh steel plates interconnected by spacers. The two mesh steel plates are placed standing, i.e., in a vertical and upright position, and concrete is poured into the gap between the upright mesh steel plates.

[0010] US 1094844 A relates to skeleton structures fabricated of metallic members adapted to be used as columns or beams in concrete reinforcements and consists of a structure composed of a series of longitudinal members arranged in angular relation to each other and having members pivotally connecting the same in such manner that the structure may be collapsed and stored or transported and may be readily opened out to its expanded condition for use.

[0011] WO 0126974 A2 and JPS59179967A disclose collapsible metal cages containing a plurality of metal main bars rotatably connected to a plurality of links.

[0012] Object of the invention

[0013] An object of the invention is to provide a prefabricated reinforcing skeletal framework, with horizontally orientated mesh layers, and that is foldable to take up less room, in for instance a truck during transport.

[0014] Another object of the invention is to provide a prefabricated reinforcing skeletal framework, which is foldable and compact during transport and erectable on site to a rigid and locked configuration. The reinforcing framework can thus withstand both tension forces and compression forces acting from the concrete.

[0015] The system can be lifted in the folded position and the bottom mesh layer hangs using the hinges. The system must withstand the load when rolling out roller nets for the top as well as loads from pump hoses etc. when casting in addition to concrete pressure. The biggest load from the concrete is the pressure when pumping / emptying concrete vats. The concrete is liquid when it puts stress on the reinforcement.

[0016] Yet another object of the invention is to provide a prefabricated reinforcing skeletal framework where only the rebars necessary for the structural integrity of the reinforced concrete is of structural grad quality, in the rest of the prefabricated skeletal framework it can be used scrap metal, cut off / leftovers of rebars or lower quality metal. Summary of the invention

[0017] In one aspect the invention relates to a prefabricated reinforcing skeletal framework that is foldable and erectable, for the construction of reinforced concrete structures, wherein the reinforcing skeletal framework comprises:

[0018] - at least two horizontally orientated mesh layers, namely a first mesh layer and a second mesh layer, and

[0019] - several spaced apart spacers connecting said two mesh layers, wherein each spacer is pivotally connected to the first mesh layer in a first connection point and wherein each spacer is pivotally connected to the second mesh layer in a second connection point, each spacer is pivotable around substantially parallel axes passing through the first and the second connection points, the two horizontally orientated mesh layers are movable relative to each other between a first folded configuration wherein the first mesh layer is adjacent the second mesh layer and a second erected configuration wherein the second mesh layer is rigidly fixed at a predetermined height above the first mesh layer, and wherein the spacers are arranged to be locked substantially perpendicular and upright to said horizontally orientated mesh layers in the second configuration and wherein the first mesh layer and the second mesh layer is arranged in substantially parallel planes in the second configuration.

[0020] The resulting technical effect of the two mesh layers being connected by spacers as disclosed above is that the reinforcing skeletal framework is erectable. Hence, the skeletal framework can be collapsed or folded so that there is no or a verry little space between the first and the second mesh layer. If the first mesh layer is resting on a horizontal surface the second mesh layer can be moved between a first configuration wherein the second mesh layer rests on top of the first mesh layer and a second configuration wherein the second mesh layer is at a predetermined height above the first mesh layer. Said height equals the length of the spacers.

[0021] The advantage of having a foldable prefabricated skeletal framework is that it saves space during transportation. When the skeletal framework is used as reinforcement in a concrete floor slab, the two mesh layers will typically be arranged as two parallel and horizontal layers with a sufficient distance between them. Foldable skeletal framework, will compared to stacking skeletal framework with such thickness on top of each other on a trailer, make room for many more skeletal framework on one trailer load. The skeletal framework can be a skeletal steel framework.

[0022] The mesh layers can comprise rebars and the rebars can be connected in a mesh by tying the rebars together in the intersections using tying wire. Other methods known to the skilled person can also be used and the method of securing the rebars to each other is not essential to the invention.

[0023] The mesh layers can be layers of Y-directional rebars held in place by relatively fewer X-directional rebars (transverse to the Y-directional rebars).

[0024] The purpose of the spacers is to maintain the position of the mesh layers relative to each other until the concrete has cured. The spacers are not intended to contribute to the structural integrity of the cured concrete. Hence, the spacer do not need to have the same material quality and strength as the rest of the skeletal framework.

[0025] When the prefabricated skeletal framework is used as reinforcement in a concrete floor slab, it is desirable that the two mesh layers are arranged in parallel planes. For the construction of other types of reinforced concrete structures, it might be need for two or more mesh layers arranged in non-parallel planes. If the mesh layers are not to be parallel, then the spacers can have different length to achieve this.

[0026] Each of the mesh layers can comprise rebars arranged in a pattern with parallel spaced apart Y-directional rebars and parallel spaced apart X-directional rebars. The Y-directional rebars can be arranged substantially transversal to the X-directional rebars.

[0027] Rebar is short for reinforcing bar.

[0028] The spacer can comprise at least one spacer bar having in each end a section of a pivot pipe being perpendicular to the spacer bar, and the two sections of pivot pipes are arranged in parallel to each other.

[0029] Each of the pipes can accommodate an X-directional rebar.

[0030] A rebar passing through a pivot pipe act as a pivoting joint (a hinge) between a mesh layer and a spacer. The length of the pivot pipe accommodating a X-directional rebar is preferably equal to or less than the space between each of the spaced apart Y-directional rebars. Thus, the spacer being prevented from sliding along the X-directional rebar and at the same time not being jammed between the X-directional rebar and transverse Y- directional rebars of each layer.

[0031] It should be understood that the terms Y-directional and X-directional is only used for the purpose of distinguishing between I defining two different directions in which rebars are arranged. This is only to make it easier for the reader to understand. The skilled person will understand that it just as well could have been written that the pipes of the spacer could be arranged onto a Y-directional rebar.

[0032] The spacer can comprise two spaced apart parallel spacer bars fixed to each other by two transverse connecting bars, and each of the spacer bars can have a pivot eye on each end.

[0033] The transverse bars can be welded to the spacer bars.

[0034] The pivot eyes accommodate X-directional rebars.

[0035] The eyes can be formed by bending the ends of the spacer bars.

[0036] The two eyes, in each end of the spacer arranged to connect to the first mesh layer, can be arranged on a opposite side of the spacer bars compare to the two eyes arranged to connect to the second mesh layer, and the x-directional rebars arranged to be accommodated inside the eyes can be on both mesh layers arranged on the inside of the skeletal framework relative to the y-directional rebars.

[0037] This has the effect that when the skeletal framework is in its folded configuration, it can have a thickness equal to the thickness of only three rebars.

[0038] The spacer can alternatively comprise a pivotal joint in between the first and the second connection point, so that the spacer can be manipulated from a folded configuration to an erected configuration. The spacer can also comprise a snap mechanism so that the spacer locks in the erected configuration. In the above disclosed embodiment, the spacer has a pivotal joint. This pivotal joint can for instance be at the middle of the spacer halfway between the connection point to the first and the second mesh layer. The pivotal joint should be arranged so that it pivots around an axis being parallel with the axis through the connection point to the first and the second mesh layer. When having this additional pivotal joint, the spacer can be folded when the skeletal framework is in its folded or collapsed configuration and when moved to the erected configuration the spacer is unfolded and secured in the erected configuration by the snap mechanism. The snap mechanism can be releasable so that the spacer can be folded again.

[0039] The skeletal framework can further comprise bracings arranged for securing the two mesh layers in the second erected configuration.

[0040] The purpose of the bracing is to maintain the position of the mesh layers relative to each other until the concrete has cured. The bracing is not intended to contribute to the structural integrity of the cured concrete. Hence, the bracing (and the spacers) does not need to have the same material quality and strength as the rest of the skeletal framework.

[0041] The bracing can comprise at least one removable rigid strut arranged between an X- directional rebar in the first mesh layer and an X-directional rebar in the second mesh layer. Said rebar of the first and the second mesh layer can be displaced in relation to each other in the axial direction of the Y-directional rebars when the skeletal framework is in its second erected configuration.

[0042] The bracing can comprise at least two rigid struts, namely a first rigid strut and a second rigid strut. Each having an eye in one end. The eye of the first rigid strut can accommodate a X-directional rebar of the first mesh layer, while the eye of the second rigid strut can accommodate a X-directional rebar of the second mesh layer. The two eyes can be displaced in relation to each other in the axial direction of the Y-directional rebars when the skeletal framework is in its second erected configuration. The two rigid struts can be secured to each other by letting them overlap a distance and fixing them to each other using at least one clamp.

[0043] The clamp can be a wire clamp or Bulldog / U-Bolt clamp. In another aspect the invention relates to a method for casting a reinforced concrete slab using a prefabricated erectable reinforcing skeletal framework. The method comprises the steps of:

[0044] - lifting a prefabricated and folded reinforcing skeletal framework into a formwork for the slab, wherein the skeletal framework comprises:

[0045] - at least two horizontally mesh layers, namely a first mesh layer and a second mesh layer, and

[0046] - several spaced apart spacers connecting said two layers, wherein each spacer is pivotally connected to the first mesh layer in a first connection point and wherein each spacer is pivotally connected to the second mesh layer in a second connection point, each spacer is pivotable around substantially parallel axes passing through the first and the second connection points,

[0047] - erecting the skeletal framework from a first collapsed configuration wherein the first mesh layer is in contact with the second mesh layer and into a second erected configuration wherein the second mesh layer is lifted to a predetermined height above the first mesh layer,

[0048] - locking the second mesh layer in said second erected configuration, and

[0049] - pouring concrete into the formwork, while the skeletal framework is held in its second erected configuration.

[0050] The method can further comprise the step of securing the skeletal framework in the second erected configuration before the step of pouring concrete. The skeletal framework can be secured in its second erected configuration by bracing, and the bracing can comprise at least one removable rigid strut arranged between an X- directional rebar in the first mesh layer and an X-directional rebar in the second mesh layer. Said rebar of the first and the second mesh layer can be displaced in relation to each other in the axial direction of the Y-directional rebars when the skeletal framework is in its second erected configuration.

[0051] Description of the figures

[0052] Fig. 1 shows a section of a prefabricated reinforcing skeletal framework according to the invention in a perspective view. The skeletal framework is erected, and bracing is in place to secure the skeletal framework in its erected position / configuration.

[0053] Fig. 2 shows the same skeletal framework as in Fig. 1 , but from a different angle and from further away. Fig. 3 shows a part of the skeletal framework where a spacer is arranged for holding a distance, i.e., height, between two mesh layers in the skeletal framework.

[0054] Fig. 4 shows the same part of the skeletal framework as in Fig. 3, but from a different angle.

[0055] Fig. 5 shows an embodiment of a spacer alone in a close up view.

[0056] Fig. 6 shows another embodiment of a spacer alone in a close up view.

[0057] Fig. 7 shows a part of the prefabricated erectable reinforcing skeletal framework in a perspective view. In Fig. 7 the skeletal framework is in its collapsed configuration / position and one can see a spacer centrally in the figure. The spacer seen in Fig.7 is a different embodiment of the spacer compared to in the previous figures.

[0058] Fig. 8 shows a section of the same skeletal framework as seen in Fig. 7. In Fig. 8 the skeletal framework is in its erected configuration / position.

[0059] Fig. 9 shows a spacer in a close up view. This spacer is the same embodiment as the one seen in Fig. 7 and Fig. 8.

[0060] Fig. 10 shows an embodiment of a bracing for fixing the skeletal framework in its erected configuration / position. Most of the mesh layer is removed from the figure, but that is only to get a better view of the bracing and its connection to the transversal rebars (X-directional rebars). In Fig. 10 the bracing is not yet secured with clamps as the one seen in Fig. 11.

[0061] Fig. 11 shows an embodiment of a clamp that can be used for securing the bracing. This embodiment is a clamp similar to a standard wire clamp.

[0062] Fig. 12 shows the prefabricated reinforcing skeletal framework in a folded configuration / position.

[0063] Fig. 13 shows the prefabricated reinforcing skeletal framework of Fig. 12 in a configuration / position in between folded and fully erected. Fig. 14 shows the prefabricated reinforcing skeletal framework of Fig. 12 and Fig. 13 now in its fully erected configuration / position.

[0064] Description of preferred embodiments of the invention

[0065] In the following embodiments of the prefabricated foldable and erectable reinforcing skeletal framework 10 will be described with reference to the figures.

[0066] As seen in Fig.1 and Fig. 2 the skeletal framework 10 comprises a first horizontally orientated mesh layer 11 and a second horizontally orientated mesh layer 12 that is connected by upright spacers 13. By horizontally orientated is meant as seen in the figures. The spacers 13 are pivotally connected to both the first and second mesh layers 11 ,12 in the connection points 21 ,22 so that all the spacers 13 can pivot in the same direction, i.e., they can all pivot around parallel axes. The effect of this is that that the two mesh layers 11,12 can move relative to each other between a collapsed or folded configuration and an erected configuration, wherein the first mesh layer 11 is locked at a predetermined height above the second mesh layer 12.

[0067] The number of spacers 13 needed is dependent on the size and the stiffness of the mesh layers 11 ,12.

[0068] The mesh layers 11 ,12 comprises horizontally orientated rebars 15 arranged in a mesh pattern. To be able to distinguish between the two direction which the rebars 15 is arranged in we refer to them as X-directional rebars 15X and Y-directional rebars 15Y. In the embodiments in the figure there are relatively fewer rebars 15 in what we have defined as the X-direction.

[0069] In Fig. 1 and Fig. 2 the skeletal framework 10 is in its erected configuration which is the position / configuration it is intended to be arranged in when cast inside a concrete floor, for instance. The skeletal framework 10 is secured in its erected configuration by bracings 14.

[0070] Fig. 3 and Fig. 4 is centred on an embodiment of a spacer 13 arranged in the skeletal framework 10. The spacer 13 comprises in this embodiment (also see Fig. 5) two parallel spacer bars 13.1 and two pivot pipes 13.2 one in each end of the spacer bars 13.1. The pipes 13.2 are arranged in parallel perpendicular to the spacer bar 13.1. Each pipe 13.2 accommodates an X-directional rebar 15X, and this makes up the pivotal connection or hinge connection between the spacer 13 and the mesh layers 11,12.

[0071] Fig. 5 shows a spacer 13 alone. The spacer 13 being the same embodiment as the one seen in Fig. 3 and Fig 4.

[0072] Fig. 6 shows an embodiment of the spacer 13 which has only one spacer bar 13.1 , but apart from that, the spacer 13 of Fig. 6 is similar to the spacer from Fig. 5.

[0073] Hence, the spacer 13 comprises in this embodiment one spacer bars 13.1 and two pivot pipes 13.2 one in each end of the spacer bar 13.1. The pipes 13.2 are arranged in parallel perpendicular to the spacer bar 13.1. Each pipe 13.2 accommodates an X- directional rebar 15X, and this makes up the pivotal connection or hinge connection between the spacer 13 and the mesh layers 11 , 12.

[0074] The pivot pipes 13.2 will keep the framework 10 steady sideways. That mean that we don't need additional bracing sideways.

[0075] Fig. 7 and Fig. 8 shows another embodiment of the spacer 13 arranged in a skeletal framework 10. In Fig. 7 the skeletal framework 10 is in its collapsed configuration and in Fig. 8 the skeletal framework 10 is in its erected configuration. This embodiment of the spacer can be made exclusively from scrape metal / rebar leftovers and comprises two spacer bars 13.1 each being bent in both ends to form a pivot eye 13.4 in each end and two transvers bars 13.3 to connect the spacer bars

[0076] 13.1 to each other. The eyes 13.4 are accommodating a X-directional rebar 15X and this makes up the pivotal connection / hinge connection between the mesh layers 11 ,12 and the spacers 13.

[0077] Fig. 9 shows the same embodiment of the spacer 13 as the one seen in Fig. 7 and Fig. 8.

[0078] The spacers 13 shown and disclosed in relation to Fig. 5 - 9 can be welded to the X- directional rebars 15X, and thus be locked in the upright position.

[0079] Fig. 10 shows and embodiment of the bracing 14. The Y-directional rebars 15Y is removed to be able to show the bracing 14 more clearly, in reality there would be Y- directional rebars 15Y in place. The bracing 14 comprises four rigid struts 14.1 , each having an eye in one end and the eye is accommodating a X-directional rebar 15X. When the skeletal framework 10 is in the folded configuration the rigid struts 14.1 can be arranged laying parallel to the mesh layers 11 , 12 and when the skeletal framework 10 is erected and is to be secured in the erected configuration the struts

[0080] 14.1 is arranged diagonally between the mesh layers as bracings 14. The struts 14.1 is long enough to overlap a meeting strut 14.1 diagonally and two and two overlapping struts 14.1 can be secured to each other using clamps 14.2, as the one seen in Fig 11. The overlap of the meeting struts 14.1 could possibly also be welded.

[0081] In a further embodiment, the bracing 14 comprises either round or square tubes welded to the end of the struts 14.1 , instead of the eyes. Fig. 12 shows a skeletal framework 10 in its folded configuration. In Fig. 13 the same skeletal framework 10 is moved to a position halfway erected. In Fig. 14 the skeletal framework 10 is fully erected and bracing 14 is in place. The skeleton framework 10 according to the invention can be used together edge elements and starter bars.

Claims

CLAIMS1. A prefabricated reinforcing skeletal framework (10) that is foldable and erectable, for the construction of reinforced concrete structures, wherein the reinforcing skeletal framework (10) comprises:- at least two horizontally orientated mesh layers, namely a first mesh layer(11) and a second mesh layer (12), and- several spaced apart spacers (13) connecting said two mesh layers (11 , 12), wherein each spacer (13) is pivotally connected to the first mesh layer (11) in a first connection point (21) and wherein each spacer (13) is pivotally connected to the second mesh layer (12) in a second connection point (22), each spacer (13) is pivotable around substantially parallel axes passing through the first and the second connection points (21 , 22), the two horizontally orientated mesh layers (11 ,12) are movable relative to each other between a first folded configuration wherein the first mesh layer (11) is adjacent the second mesh layer (12) and a second erected configuration wherein the second mesh layer (12) is rigidly fixed at a predetermined height above the first mesh layer (11), and wherein the spacers (13) are arranged to be locked substantially perpendicular and upright to said horizontally orientated mesh layers (11 ,12) in the second configuration and wherein the first mesh layer (11) and the second mesh layer (12) is arranged in substantially parallel planes in the second configuration.

2. The skeletal framework (10) according to claim 1 , wherein each of the mesh layers (12, 13) comprises rebars (15) arranged in a pattern with parallel spaced apart Y-directional rebars (15Y) and parallel spaced apart X-directional rebars (15X), wherein the Y-directional rebars (15Y) are arranged substantially transversal to the X-directional rebars (15X).

3. The skeletal framework (10) according to claim 1 , wherein the spacer (13) comprises at least one spacer bar (13.1) having in each end a section of a pivot pipe (13.2) being perpendicular to the spacer bar (13.1), and the two sections of pivot pipes (13.2) are arranged in parallel to each other.

4. The skeletal framework (10) according to claim 3, wherein each of the pivot pipes (13.2) accommodate an X-directional rebar (15X).

5. The skeletal framework (10) according to claim 1, wherein the spacer (13) comprises two spaced apart parallel spacer bars (13.1) fixed to each other by two transverse connecting bars (13.3), and wherein each of the spacer bars (13.1) on each end has a pivot eye (13.4).

6. The skeletal framework (10) according to claim 5, wherein the pivot eyes (13.4) accommodate X-directional rebars (15X).

7. The skeletal framework (10) according to claim 5 or 6, wherein the pivot eyes(13.4) are formed by bending the ends of the spacer bars (13.1).

8. The skeletal framework (10) according to claim 7, wherein the two pivot eyes(13.4), in each end of the spacer (13) arranged to connect to the first mesh layer (11), is arranged on a opposite side of the spacer bars (13.1) compared to the two pivot eyes (13.4) arranged to connect to the second mesh layer (12), and wherein the X-directional rebars arranged to be accommodated inside the pivot eyes (13.4) is on both mesh layers (11, 12) arranged on the inside of the skeletal framework (10) relative to the Y-directional rebars (15Y).

9. The skeletal framework (10) according to claim 1 , wherein the spacer (13) comprises a pivotal joint in between the first (21) and the second connection point (22), so that the spacer can be manipulated from a folded configuration to an erected and upright configuration, and wherein the spacer comprises a snap mechanism to lock the spacer in the erected configuration .

10. The skeletal framework (10) according to claim 1, wherein the prefabricated erectable reinforcing skeletal framework (10) further comprises bracings (14) arranged for securing the two mesh layers (11, 12) in the second erected configuration.

11. The skeletal framework (10) according to claim 10, wherein the bracing (14) comprises at least one removable rigid strut (14.1) arranged between an X- directional rebar (15X) in the first mesh layer (11) and an X-directional rebar (15X) in the second mesh layer (12), said rebar of the first mesh layer (11) and the second mesh layer (12) is displaced in relation to each other in the axial direction of the Y- directional rebars (15Y) when the skeletal framework (10) is in its second erected configuration.

12. The skeletal framework (10) according to claim 10 or 11, wherein the bracing (14) comprises at least two rigid struts, namely a first rigid strut (14.1) and a second rigid strut (14.1), each having an eye in one end, the eye of the first rigid strut accommodates a X-directional rebar (15X) of the first mesh layer (11), while the eye of the second rigid strut (14.1) accommodates a X-directional rebar (15X) of the second mesh layer (12), and wherein the two eyes is displaced in relation to each other in the axial direction of the Y-directional rebars (15Y) when the skeletal framework (10) is in its second erected configuration, and wherein the two rigid struts (14.1) is secured to each other by letting them overlap a distance and fixing them to each other using at least one clamp (14.2).

13. A method for casting a reinforced concrete slab using a prefabricated erectable reinforcing skeletal framework (10), wherein the method comprises the steps of:- lifting a prefabricated and folded reinforcing skeletal framework (10) into a formwork for the slab, wherein the skeletal framework (10) comprises:- at least two horizontally orientated mesh layers, namely a first mesh layer (11) and a second mesh layer (12), and- several spaced apart spacers (13) connecting said two mesh layers (11, 12), wherein each spacer (13) is pivotally connected to the first mesh layer (11) in a first connection point (21) and wherein each spacer (13) is pivotally connected to the second mesh layer (12) in a second connection point (22), each spacer (13) is pivotable around substantially parallel axes passing through the first and the second connection points (21, 22),- erecting the skeletal framework (10) from a first collapsed configuration wherein the first mesh layer (11) is in contact with the second mesh layer (12) and into a second erected configuration wherein the second mesh layer (12) is lifted to a predetermined height above the first mesh layer (11),- locking the second mesh layer (12) in said second erected configuration, and- pouring concrete into the formwork, while the skeletal framework (10) is locked in its second erected configuration.

14. The method for casting a reinforced concrete slab according to claim 13, wherein the method comprises the step of securing the skeletal framework in the second erected configuration before the step of pouring concrete, the skeletal framework is secured in its second erected configuration by bracings (14), saidbracing comprises at least one rigid strut (14.1) arranged between an X-directional rebar (15X) in the first mesh layer (11) and an X-directional rebar (15X) in the second mesh layer (12).

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