A FIXING

Abstract

A ratchet fixing 5 for connecting an insulation layer 4 to a precast concrete panel 2, a precast concrete panel system 1 comprising the fixing 5 and a method for forming an insulated precast concrete panel system 1 comprising fixing an insulation layer 4 to a concrete panel 2 with fixings 5 in which the fixing 5 is made up of an insulation layer penetrating portion 18 and a concrete penetrating portion 19 contiguous with the insulating layer penetrating portion 18, the insulation layer penetrating portion 18 having a disc-like tension head 20 for abutting against the outer surface of the insulation layer 4 and a pawl 22 and ratchet 25 for securing the tension head 20 to the insulation layer penetrating portion 18.

Claims

1. A fixing for connecting an insulation layer to a precast concrete panel comprising: an insulation layer penetrating portion and a concrete penetrating portion contiguous with the insulation layer penetrating portion wherein the insulation layer penetrating portion comprises a flexible tie.

2. A fixing as claimed in claim 1 wherein the insulation layer penetrating portion further comprises a tension head attachable to the flexible tie.

3. A fixing as claimed in claim 2 wherein the flexible tie comprises a ratchet attachable to the tension head at a pawl.

4. A fixing as claimed in claim 3 wherein the ratchet comprises through holes in the tie.

5. A fixing as claimed in claim 3 or claim 4 wherein the pawl comprises a slot in the tension head.

6. A fixing as claimed in claim 5 wherein the tension head comprises a collar surrounding the slot.

7. A fixing as claimed in any of claims 2 to 6 wherein the tension head comprises indents to define finger grips in the tension head.

8. A fixing as claimed in any of claims 1 to 7 wherein the concrete penetrating portion comprises a wall plug.

9. A fixing as claimed in claim 8 wherein the wall plug comprises a substantially cylindrical head.

10. A fixing as claimed in claim 9 wherein the substantially cylindrical head comprises at least one laterally extending fin for maximizing grip of the wall plug on concrete.

11. A fixing as claimed in claim 9 or claim 10 wherein the substantially cylindrical head comprises at least one notch for maximizing grip of the wall plug on concrete.

12. A fixing as claimed in claim 8 wherein the wall plug comprises a substantially T-shaped head.

13. A fixing as claimed in any of claims 1 to 12 wherein the concrete penetrating portion comprises a flange for stabilising the fixing in position during concrete pouring.

14. A fixing as claimed in claim 13 wherein the flange extends laterally outwards from the concrete penetrating portion.

15. A fixing as claimed in any of claims 1 to 14 further comprising at least one rib for strengthening the fixing.

16. A fixing as claimed in claim 15 wherein the at least one rib is provided on the insulation layer penetrating portion.

17. A fixing as claimed in claim 15 or 16 wherein the at least one rib is provided on the concrete penetrating portion.

18. A precast concrete panel system comprising a fixing as claimed in any of claims 1 to 17.

19. A precast concrete panel system as claimed in claim 18 wherein the system comprises a precast concrete panel reinforced with rebar and insulation fixed to the precast concrete panel by the fixing wherein the rebar and the fixing are spatially separate within the system.

20. A precast concrete panel system as claimed in claim 18 or claim 19 wherein the insulation layer comprises insulation board.

21. A precast concrete panel system as claimed in claim 20 wherein the insulation board comprises expanded polystyrene.

22. A method for forming an insulated precast concrete panel system comprising fixing an insulation layer to a concrete panel with fixings as claimed in any of claims 1 to 17.

23. A method as claimed in claim 22 comprising fitting the fixings to the insulation layer via the insulation layer penetrating portion, laying the insulation layer in a deck and pouring concrete into the deck to encapsulate the concrete penetrating portion of the fixings.

24. A method as claimed in claim 23 further comprising the step of constructing a rebar in the deck before pouring the concrete.

25. A method as claimed in claim 24 wherein the rebar is spatially separated from the fixings to prevent thermal bridging.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The invention will be more clearly understood from the following description of an embodiment thereof, given by way of example only, with reference to the accompanying drawings, in which:-

[0037] FIG. 1 is a cross-sectional view through a precast concrete panel system of the invention made up of a precast panel adapted to define a window opening for receiving a window in which the precast panel is laid on the flat and has an upper concrete layer over a lower insulation layer and the insulation layer is anchored to the concrete panel by a two-part ratchet fixing/anchor extending between the insulation layer and the concrete panel;

[0038] FIG. 2 is an external plan view of the precast panel system of FIG. 1 from the insulation layer side of the precast concrete panel with the render finish omitted to reveal the tension heads of the multiple ratchet fixings visible on the insulation layer;

[0039] FIG. 3 is a partially cutaway view of the precast concrete panel of FIG. 2 showing the wall plug of the ratchet fixings embedded in the concrete layer;

[0040] FIG. 4 is an enlarged perspective view from above and one side and from the concrete penetrating portion of the ratchet fixing;

[0041] FIG. 5 is a perspective view from above and one side of the two-part ratchet fixing of FIG. 4 with the tension head of the ratchet fixing removed i.e. before use of the ratchet fixing;

[0042] FIG. 6 is a perspective view from above and one side and from the insulating penetrating portion of the ratchet fixing;

[0043] FIG. 7 is a perspective view from above and one side and from the insulating penetrating portion of the two-part ratchet fixing with the tension head removed i.e. before use of the ratchet fixing;

[0044] FIG. 8 is a plan view of the ratchet fixing;

[0045] FIG. 9 is a perspective view from above and one side of a second embodiment of a fixing of the invention, with the tension head omitted, in which the wall plug of the concrete penetrating portion is substantially T-shaped and the fixing is provided with stabilising and strengthening ribs to reinforce the fixing;

[0046] FIG. 10 is an enlarged perspective view from above and one side of the tension head of the fixing of FIG. 9;

[0047] FIG. 11 is a side elevation of the tension head of FIG. 10;

[0048] FIG. 12 is a cross-sectional view through the tension head of FIG. 11, and

[0049] FIG. 13 is an enlarged side elevation of the T-shaped wall plug of the concrete penetrating portion of the fixing of FIG. 9 with strengthening ribs provided adjacent the stabilising flange of the wall plug on the insulation penetrating portion.

DETAILED DESCRIPTION OF THE INVENTION

[0050] As shown in the drawings, a precast concrete panel system of the invention is generally indicated by the reference numeral 1 and (when viewed on the flat as shown in FIG. 1) is made up of a precast panel 2 having an upper concrete layer 3 and a lower insulation layer 4 typically of expanded polystyrene or similar secured to the concrete layer 3 by a first embodiment of a two-part ratchet anchor or fixing 5 of the invention. The concrete layer 3 is also provided with a grid of steel rebar (not shown) to reinforce the precast panel 2 while an external render finish 6 is provided on the outer surface of the insulation layer 4 and plasterboard 7 is mounted over a cavity 8 defined by timber stud 9 at the outer face of the concrete layer 3. The cavity 8 contains internal insulation material 10.

[0051] As shall be explained more fully below, the ratchet fixing 5 securely attaches the insulation layer 4 to the concrete layer 3 and is independent of the grid of steel rebar i.e. does not contact the grid of steel rebar thereby minimising thermal bridging across the panel system of the invention whilst, being flexible, the ratchet fixing 5 offers room for expansion and contraction of concrete during curing.

[0052] The precast panel 2 is shaped to define scarf joints 11 for interconnecting individual precast panels 2 during the construction of a building.

[0053] As shown particularly in FIG. 2, the precast panel 2 is substantially rectangular in shape and has a bottom edge 12, a top edge 13 and first and second side edges 14,15 connecting the bottom and top edges 12,13. A window opening 16 is defined in the precast panel 2 for receiving a window 17.

[0054] FIGS. 4 to 8 show enlarged views of the first embodiment of the ratchet fixing 5. As shown in the drawings, the ratchet fixing 5 is made up of an insulation layer penetrating portion 18 and a concrete penetrating portion 19 contiguous with the insulation layer penetrating portion 18. The insulation layer penetrating portion 18 has a disc-like tension head 20 for abutting against the outer surface of the insulation layer 4 as shown in FIGS. 2 and 3 and for urging the insulation layer 4 against the concrete layer 3 in use. The tension head 20 has a rectangular central slot 21 which defines a pawl 22 while a series of circular openings 23 are arranged circumferentially around the central slot 21.

[0055] The insulation layer penetrating portion 18 is also made up of a substantially rectangular elongate flexible tie 24 which extends between the tension head 20 and the concrete penetrating portion 19. More particularly, the flexible tie 24 is insertable in the central slot 21 of the tension head 20 and is securely attachable to the pawl 22 in the central slot 21 via a ratchet 25 formed in the flexible tie 24. In the present embodiment, the ratchet 25 is defined by through holes or notches 26 in the flexible tie 24. However, as will be appreciated by those skilled in the art, the ratchet 25 can be defined by teeth or similar structures on the tie 24 if desired.

[0056] The concrete penetrating portion 19 is made up of a circular stabilising flange 27 extending laterally outwards from the concrete penetrating portion 19 for stabilising the ratchet fixing 5 in position during concrete pouring. The circular stabilising flange 27 has a diameter smaller than that of the tension head 20. A wall plug 28 is mounted on the stabilising flange 27 for anchoring and embedding the concrete penetrating portion 19 in the concrete layer 3 of the precast panel 2. As shall be explained more fully below, the concrete penetrating portion 19, and in particular the wall plug 28, is encapsulated in the concrete layer 3 during manufacture of the precast panel system 1 of the invention.

[0057] In order to provide a highly effective anchor in the concrete layer 3, the wall plug 28 is made up of a substantially cylindrical head 29 having a pointed tip 30 and first and second pairs of laterally extending fins 31, 32 respectively for maximising grip in the concrete layer 3. The cylindrical head 29 is also provided with a first and second pair of notches 33, 34 respectively between the fins 31, 32 to further enhance the grip of the wall plug 24 in the concrete layer 3.

[0058] FIGS. 9 to 13 show a second embodiment of a ratchet fixing 5 of the invention similar to the ratchet fixing of FIGS. 1 to 8 and like numerals indicate like parts. However, in the present embodiment, the wall plug 28 of the concrete penetrating portion 19 is substantially T-shaped and the ratchet fixing 5 is provided with stabilising and strengthening ribs 36 to reinforce the ratchet fixing 5. As shown in the drawings, in the present embodiment, three strengthening ribs 36 are provided on the insulation penetrating portion 18, and more particularly the elongate tie 24, adjacent the stabilising flange 27. The strengthening ribs 36 extend laterally outwards from the longitudinal axis defined by the elongate tie 24 to strengthen engagement between the ratchet fixing 5 and insulation layers 4 in use i.e. the laterally extending ribs 36 increase surface contact between the ratchet fixing 5 and the insulation layer 4 to assist in stabilising the ratchet fixing 5 in the insulation layer 4 whilst still allowing the elongate tie 24 to flex in the insulating layer 4.

[0059] If desired, additional or alternatively positioned strengthening ribs 36 can be provided on the insulation penetrating portion 18.

[0060] In the present embodiment, the circular tension head 20 of the ratchet fixing 5 is provided with peripheral indents 37 to define finger grips 38 for gripping and positioning the tension head 20 in use. The tension head 20 is also provided with a central collar 39 surrounding the central slot 21. The central collar 39 serves to assist in supporting the elongate tie 24 in the toothed pawl 22 of the rectangular central slot 21 in use.

[0061] As shown particularly in FIG. 13, the wall plug 28 is formed as a substantially T-shaped head 40 to assist in anchoring the concrete penetrating portion 19 in concrete. The T-shaped head 40 has an upright portion 41 and an arcuate cross or transverse portion 42. The arcuate transverse portion 42 is curved towards the upright portion 41 and the flange 27 to assist in strengthening the anchoring relationship between the ratchet fixing 5 and the concrete layer 3 in use. The upright portion 41 and the arcuate transverse portion 42 of the T-shaped head 40 are further provided with head ribs 43 to further enhance surface contact with the concrete layer 3 and acts to maintain rigidity of the fixing 5.

[0062] The ratchet fixing 5 of the present embodiment can be easily and simply manufactured using injection moulding techniques.

[0063] The precast concrete panel system 1 of the invention can be manufactured by first constructing a form or deck on the flat in accordance with the shape and size of precast panel 2 required. The deck is made up of supporting sides having a depth greater than the final depth required in the precast concrete panel 2. By way of example for a precast panel system 1 as shown in FIG. 2 having a height of 2400 mm, a width of 2200 mm and a thickness of 150 mm. The total thickness can be 370 mm, comprising 4 mm Hard wall Internal Finish, 12.5 mm Plaster boarding, 44 mm Timber Battens, 150 mm Reinforced Concrete, 150 mm EPS Insulation, 9 mm External Rendering with Reinforced Fiberglass Mesh cloth and Finished using a Silicone Topcoat. An insulation layer 4 in the form of pre-formed perforated insulation boards 4 (e.g. expanded polystyrene), suitable for use with the ratchet fixing 5 are then fitted with the desired number and layout of ratchet fixings 5.

[0064] In particular, elongate ties 24 of the ratchet fixing 5 with the tension head 20 removed as shown in FIGS. 5 and 7 are inserted through the insulation boards 4 so that the free end 35 of each elongate tie 24 is at the outer surface of the insulation layer 4 as shown in the drawings and the stabilising flange 27 of each concrete penetrating portion 19 abuts the opposite internal face of the insulation layer 4. The tension heads 20 are then engaged with the free end 35 of each elongate tie 24 by inserting the free ends 35 of the elongate ties 24 in the central slots 21 of the tension heads 20 so that the pawls 22 in the central slots 21 irreversibly engage the ratchets 25 on the elongate ties 24. The engagement of each pawl 22 and ratchet 25 can be tightened as needed to increase grip or tension across the insulation layer 4 as required.

[0065] The insulation boards 4 are then laid face down in the deck i.e. with the tension heads 20 disposed downwards and the wall plugs 28 disposed upwards in the deck. Upon completion of the above steps, concrete is then poured into the deck to encapsulate the wall plugs 28 of the ratchet fixings 5 and the steel rebar structural support. The resultant precast concrete panel system 1 is a structurally sound, highly insulated structure which exhibits minimal thermal bridging characteristics of about 0.002 W/m.sup.2K or greater and which is suitable for delivery to a construction site for building construction.

[0066] If desired, a rebar can be constructed in the deck before pouring concrete e.g. in the present example a grid of steel rebar made up 506 mm iron ribs placed around the edges of the deck and at centres that do not interfere with the ratchet fixings 5 during manufacturing can be incorporated into the deck.

[0067] The ratchet fixing 5 can be formed from any suitable material such as plastics, nylon and the like and can be sized as required. For example, for the precast concrete panel system described above in FIGS. 1 to 8, a ratchet fixing 5 having an overall length of about 203 mm is suitable with the tension head having a thickness of about 3 mm, the elongate tie 24 having a length of about 150 mm, the stabilising flange 27 having a thickness of about 5 mm and the concrete penetrating portion 19 and in particular the wall-plug 28 having a length of about 50 mm for embedding in the concrete layer 3 and a maximum width of about 30 mm. Such a ratchet fixing 5 exhibits thermal bridging of less than half that of known fixings which, at best, exhibit thermal bridging of about 0.02 W/m.sup.2k. It is envisaged various lengths ranging from 250 mm up to 400 mm can be embodied depending on U-value requirements and insulation options. For example, the ratchet fixing of FIGS. 9 to 13 can have an insulation layer penetrating portion 3 length of about 310 mm, a wall plug length of about 30 mm, a T-shaped head 39 width of about 35 mm and thickness of about 13 mm, a flange 27 diameter of about 28 mm, a tension head 20 diameter of about 60 mm and thickness of about 11 mm.

[0068] In an embodiment there is provided a conical flange positioned near the inside of the tension head, whose function is to hold a second or a stronger pawl depending on kN/mm required.

[0069] In the specification the terms comprise, comprises, comprised and comprising or any variation thereof and the terms include, includes, included and including or any variation thereof are considered to be totally interchangeable and they should all be afforded the widest possible interpretation and vice versa.

[0070] The invention is not limited to the embodiments herein described which may be varied in construction and detail without departing from the scope of the invention.