WO2014089611A1

WO2014089611A1 - Sacrificial formwork

Info

Publication number: WO2014089611A1
Application number: PCT/AU2013/001436
Authority: WO
Inventors: William Harm ROUW
Original assignee: Omega Grating Pty Ltd
Priority date: 2012-12-10
Filing date: 2013-12-10
Publication date: 2014-06-19

Abstract

Formwork (10) for a concrete construction (18). The formwork includes at least one section to define at least part of an edge or side of the concrete construction (18). A plurality of reinforcing mounts (26) are provided on the at least one section for mounting concrete reinforcing (32). The reinforcing mounts (26) are engageable with a fastener (28) for attaching a superstructure (40) to the concrete construction (18).

Description

Sacrificial Formwork

Field of the invention

The present invention relates to formwork for a concrete construction. In particular, the invention relates to sacrificial formwork for a concrete construction, which means that the formwork bonds to the concrete construction, possibly by being partly embedded in the concrete construction. The invention also relates to a method of concrete construction and a method of forming formwork for concrete constructions. While the invention has been described primarily in respect of concrete slabs, it is to be appreciated that the invention is not limited thereto and may be used for other types of concrete constructions such as precast panels. Background of the invention

US patent number 3479785 describes a form of sacrificial formwork in the form of a metal template to which a number of inserts are formed. The metal template is secured to a length of timber which serves, together with the template, as the formwork. The template remains embedded in the concrete and in this sense is sacrificial. The length of timber is removed. The template has frustoconical inserts extending from one side thereof which will become embedded in the concrete once poured. The inserts included an internally threaded bore which will be accessible once the length of timber has been removed. A bolt engages in the bore to secure a superstructure such as an angle member to the concrete.

This arrangement has some shortcomings because the template does not form the whole side of the formwork and therefore does not provide much protection to the side or edge of the concrete. Furthermore, the inserts, while embedded into the concrete are bound to the concrete only by the bond between the concrete and the inserts.

Therefore, it is an object with a present invention to provide formwork or a method of concrete construction or a method of forming formwork which overcomes or at least addresses some of the abovementioned disadvantages.

It is also an object of the present invention to provide formwork for or a method of concrete construction, or a method of forming formwork which provides the public with a useful choice over known methods. Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art. Summary of the invention

In accordance with a first aspect of the present invention, there is provided form work for a concrete construction, the formwork including: at least one section to define at least part of an edge or side of the concrete construction; and a plurality of reinforcing mounts provided on the at least one section for mounting concrete reinforcing, wherein said reinforcing mounts are each engageable with a fastener for attaching a superstructure to the concrete construction.

The section may comprise any suitable shape to form at least part of a side or edge of any concrete construction. The invention has particular application to concrete slab constructions. Therefore, it is particularly preferred that the section forms a side of the slab along the thickness direction. As such, the section may extend for the whole thickness of the slab. Additionally, preferably the section forms part of the top surface by means of a top wall or flange and the bottom surface of the slab by means of a bottom wall or flange immediately adjacent to the formed side. Accordingly, the section is most suitably channel shaped. In addition, the channel may include a return from the top flange and optionally a return from the bottom flange. These returns will become embedded in the concrete and therefore serve to bond the section to the concrete construction. As it will be appreciated, a channel section creates an external region which defines the side of the slab in the thickness direction, together with an upper and lower flange immediately adjacent to the side. The channel or section also creates an internal region into which the concrete flows to envelop the reinforcing mounts and the returns. The returns thus extend into the internal region. The channel section could be a C-section with its walls or flanges arranged at right-angles to each other. However, rounded C-sections are also possible. An I-section might also be used in the present invention. Preferably the sections are of uniform cross-section. The sections may be provided in predetermined lengths. Alternatively, the sections may be provided in indefinite length and cut to size on site. In this case, the reinforcing mounts may be secured after cutting to size.

Suitably, a plurality of such sections will be joined to define the outer periphery of the concrete slab. However, it is not essential that the formwork of the present invention be used on all sides of a slab. For example, in the design of a floor slab with a balcony extension or portion, the formwork of the present invention may only be used on the balcony extension where the formwork will remain to form the edges of the balcony extension. The formwork may then be used for the mounting of balustrade sections, for example. The remaining portion of the floor slab may use conventional formwork which is removed in the conventional fashion.

Where sections are joined, they may be mitred joints and/or the sections may be welded together or may be joined using joining plates with fasteners, which are later removed once the concrete has set.

The reinforcing mount may be provided in a variety of forms including short cylindrical members such as ferrules or tubes. The reinforcing mounts could be frustoconical. Suitably, the reinforcing mounts are provided on any face of the section so as to be embedded in the concrete once poured. Most preferably, the mounts are provided to extend from the wall of the section which is aligned with the thickness direction of the slab. However, it is also possible that the reinforcing mounts extend from the underside of the top flange or from the upper side of the bottom flange. Any combination of these arrangements may be employed in a section.

The reinforcing mounts may be attached to the section. For example, they may be secured by welding or an adhesive. In a most preferred form of the invention, the reinforcing mounts may be secured to the sections by the use of a fastener. This may be the same fastener which will ultimately be used to attach the superstructure. Alternatively, the same fastener might not be used, as the size of the fastener depends on the superstructure being fitted. High grade bolts (generally Grade 8.8) are used in construction industry. Temporary bolts may be used for fixing the reinforcing mounts to the section and are prefereably discarded, and replaced with an appropriate fastener to attach the superstructure.

For this purpose, each reinforcing mount preferably has a threaded bore to receive a fastener such as a screw or bolt. This threaded bore suitably aligns with a hole in the section to permit passage of the fastener. The location of the reinforcing mounts and the holes is preferably predetermined to align with parts of the superstructure which will be attached to the concrete construction.

The superstructure may include a wide variety of structures attachable to the concrete construction, post pour. The superstructure may include a balcony or a railing, an awning or facade, just to name a few examples. The superstructure may be above, to the side of, or suspended from the concrete construction.

The reinforcing mounts are adapted to mount reinforcing by locating and/or securing the reinforcing, which may comprise reinforcing bars. The reinforcing mounts may include a retainer to locate and/or secure the reinforcing. For example, the reinforcing mounts may include a through-hole which enables insertion of a reinforcing bar therethrough. Where there is a plurality of reinforcing mounts arranged in a line, preferably their through-holes align to permit passage of the reinforcing bars. The retainer to locate and/or secure the reinforcing may come in a variety of other forms. For example, the reinforcing mounts may have a hook end. The reinforcing mounts may have a barbed or threaded recess to retain the end of the reinforcing bar. In the claimed method of the present invention, the method may include inserting the reinforcing into the retainer.

In an alternative form of the invention, the reinforcing bar might be welded to the reinforcing mounts. The claimed method may also include the step of welding. In accordance with the second aspect of the present invention, there is provided a method of concrete construction comprising: providing formwork to define a concrete construction, the formwork including at least one section to define at least part of an edge or side of the concrete construction, the at least one section including a plurality of reinforcing mounts wherein each of said reinforcing mounts is engageable with a fastener for attaching a superstructure to the concrete construction; and mounting reinforcing to the reinforcing mounts.

Suitably, the method also includes pouring concrete and allowing the concrete to set and form a permanent bond to the section and the reinforcing mounts. The section thus remains with the concrete construction and in this sense becomes sacrificial formwork. The method may further comprise attaching a superstructure to the concrete construction by using the fasteners which engage with the reinforcing mounts. Alternatively, the same fastener might not be used, as the size of the fastener depends on the superstructure being fitted. Cheap bolts may be used for fixing the reinforcing mounts to the section and are prefereably discarded, and replaced with an appropriate fastener to attach the superstructure.

In a preferred form of the invention where the reinforcing mounts are initially attached to the section by a fastener, this fastener may be removed after the concrete pour, the superstructure positioned and then attached by using a suitable fastener.

Any of the features described above in connection with the first aspect of the invention may be applied to the second aspect of the invention.

In accordance with a third aspect of the invention, there is provided, a method of forming formwork for cast concrete constructions, the method including: forming from sheet metal, a section defining an internal region and an external region to define at least part of an edge or side of the concrete construction, with a plurality of holes in predetermined locations in a wall of the section; and at each of said holes, positioning a reinforcing mount in said internal region, wherein said reinforcing mount is engageable with a fastener for attaching a superstructure to the concrete construction.

The section may be formed from sheet metal by initially cutting to size and forming the holes by punching, laser cutting or any other appropriate means. Secondly, the sheet metal may be shaped in a press, folder or roll forming machine.

In a preferred form of the method, a fastener is positioned through each of the holes in the section to be received in the associated reinforcing mount to hold the reinforcing mount in position in the internal region. Further, the method may include locating and/or securing reinforcing in the reinforcing mounts. Further, the method may include pouring concrete so that the concrete flows into the internal region and envelops the reinforcing mounts. The concrete may be allowed to set and permanently bond to the section and the reinforcing mounts.

The method may further include removing each of the fasteners and attaching the superstructure by inserting the fasteners through the superstructure and back into engagement with the reinforcing mounts.

In accordance with a fourth aspect of the present invention, there is provided, formwork for cast concrete constructions including: a section of sheet metal formwork, the section defining an internal region for concrete flow and an external region to define at least part of an edge or side of the concrete construction, with a plurality of holes in predetermined locations in a wall of the section; a reinforcing mount positionable at each of said holes in said internal region, wherein said reinforcing mount is engageable with a fastener for attaching a superstructure to the concrete construction. As used herein, except where the context requires otherwise, the term "comprise" and variations of the term, such as "comprising", "comprises" and "comprised", are not intended to exclude further additives, components, integers or steps.

Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

Brief description of the drawings

In order that the invention may be more fully understood, one embodiment will now be described by way of example with references to the Figures in which:

Figure 1 is a longitudinal sectional view through a part of a slab, illustrating the sacrificial formwork in accordance with a first preferred embodiment;

Figure 2 is a longitudinal sectional view through a part of a slab, illustrating sacrificial formwork according to a second preferred embodiment of the present invention; Figure 3 is a longitudinal sectional view through a part of a slab, illustrating sacrificial formwork according to a third preferred embodiment of the present invention;

Figure 4 is a transverse sectional view through A-A of the slab of any of Figures 1, 2 or

3; Figure 5 is a longitudinal sectional view through part of a slab showing sacrificial formwork in accordance with a fourth embodiment of the present invention;

Figure 6 is a transverse sectional view through B-B of Figure 5;

Figure 7 is a longitudinal sectional view through part of a slab showing sacrificial formwork according to a fifth embodiment of the present invention; Figure 8 is a plan view of part of the slab illustrated in Figure 7;

Figure 9 is a transverse sectional view through C-C of Figure 7;

Figure 10 is a plan view of a larger portion of a slab, illustrating how sections of sacrificial formwork define a formed edge along the portion of the slab;

Figure 1 1 is a longitudinal sectional view of a part of a slab, showing sacrificial formwork according to a sixth embodiment of the present invention together with a superstructure attached to the sacrificial formwork;

Figure 12 is a longitudinal section through a part of a slab, showing sacrificial formwork according to a seventh embodiment of the present invention, together with a superstructure attached to the formwork; Figure 13A is a longitudinal section corresponding to Figure 11, except with an alternative type of superstructure attached to the formwork;

Figure 13B is a longitudinal section through a part of a slab showing sacrificial formwork according to an eighth embodiment of the present invention, together with a superstructure attached to the formwork; Figure 14 is a longitudinal section corresponding to Figure 12, except with an alternative type of formwork attached; Figure 15 is a plan view of a part of the slab shown in Figure 1 .

Detailed description of the embodiments

Figure 1 illustrates a first preferred form of the sacrificial form work 10 comprising a section in the form of a C-channel. The channel is comprised of a side wall 12, a top flange 14 and a bottom flange 16. The sacrificial formwork 10 has been erected as formwork to define the edge of a slab 18, only part of which is shown in Figure 1. The slab 18 has a thickness and the side wall 12 extends in the thickness direction, thus forming this boundary of the slab. Additionally, the top flange 14 and the bottom flange 16 protect the corners of the slab 18. The channel section also includes a return 20 from the top flange 14 and a return 22 from the bottom flange 16. These returns 20,22 become embedded in the slab 18 when the concrete is poured.

The side wall 12 also includes holes 24. In the embodiment shown in Figure 1, there are two rows of holes, one above the other, each row including two holes (as depicted in Figure 4). However, in preferred forms of the invention, each row may contain any number of holes, depending upon the superstnlcture to be mounted to the slab 18. The holes 24 may be regularly spaced. Ideally, the holes 24 are specifically located to accommodate matching holes in the superstructure as will be explained in connection with Figures 11 onwards.

Positioned at each hole is a reinforcing mount 26. Each reinforcing mount 26 has an internally threaded bore which is arranged substantially co-axial with the associated hole 24. The reinforcing mount 26 is retained in position by receipt of a threaded fastener 28, in this case a bolt.

In a preferred method according to the invention, the channel section is formed from sheet metal. Initially, the sheet metal is cut to length and the holes 24 are accurately punched, drilled or laser/plasma cut. The sections are then shaped in a press, folder or roll former according to the desired cross-sectional shape. In the case of Figure 1, the bottom return 22 is at right angles to the bottom flange 16, whereas the top return 20 is at an oblique angle to the top flange 14. In Figures 2, 3, 5 and 7 both the top and bottom returns are at right angles to their respective top and bottom flanges. In the embodiments of Figures 11, 12, 13A, 13B and 14, both of the returns are arranged at an oblique angle to their respective top and bottom flanges. In all cases, the bottom flange 16 extends further along the slab 18 than the top flange 14. A wide variety of cross-sectional shapes is permissible and the illustrated shapes shall in no way be seen as limiting.

Following shaping of the channel section, the reinforcing mounts 26 are positioned at respective holes 24. A bolt 28 is inserted into the threaded bore of the reinforcing mount 26 to secure the reinforcing mount 26 to the channel section.

Reinforcing is then mounted to the reinforcing mounts 26. In the examples illustrated in Figures 1 to 4, each of the reinforcing mounts 26 has a through-hole 30, arranged at 90° to the threaded bore and substantially aligned with the longitudinal direction of the channel section. Each row of reinforcing mounts 26 is arranged with the through-holes 30 aligned so that reinforcing in the form of a reinforcing bar 32 may be inserted therethrough, as best shown in Figure 4. The reinforcing bar 32 may be of any suitable length.

Once the sacrificial formwork 10 and the reinforcing bar(s) have been assembled, together with any other required formwork, the slab 18 is poured. As will be understood from a study of the channel section, the channel section defines an internal region in which the reinforcing mounts 26 and the reinforcing bars 32 are disposed. The concrete flows into this internal region and envelops the reinforcing mounts 26 and the reinforcing bars 32. These, together with the returns 20, 22 become embedded in the slab 18. The concrete of the slab 18 is allowed to cure and harden and at the appropriate time, any non-sacrificial formwork is removed. The sacrificial formwork 10 remains in position. The sacrificial formwork may be used to attach a superstructure 40 to the slab 18 (see Figures 11 to 15). Specifically, the superstructure 40 is attached by use of the reinforcing mounts 26. The reinforcing mounts 26 thus have dual functionality. In order to attach a superstructure 40 (for example see Figures 11 onwards), the bolt 28 is removed from the reinforcing mount 26. Suitably, the superstructure 40 will have holes which align with the holes in the sacrificial formwork 10. The superstructure 40 is positioned at the slab 18 with the holes in alignment and appropriate mounting bolts are inserted into the reinforcing mounts 26 and secured therein to secure the superstructure 40 to the slab 18. The holes in the sacrificial formwork which are positioned during manufacture ensure accurate location of the reinforcing mounts 26 and thus accurate placement of the superstructure. The subsequent Figures show alternative embodiments of the present invention. Many of the parts are the same as with the first embodiment and therefore like numerals will be used to represent like parts. The differences will now be explained.

As already mentioned, the embodiments in Figures 2 and 3 have different shaped returns 20,22. The embodiment of Figure 3 only includes a single row of reinforcing mounts 26.

In the embodiment illustrated in Figures 5 and 6, there is a single row of reinforcing mounts 26. These reinforcing mounts 26 do not have through-holes aligned with the longitudinal direction of the channel section. Instead, the reinforcing 32 extends away from the reinforcing mount 26 in a direction which aligns with the longitudinal axis of the reinforcing mount 26. For this purpose, the reinforcing mount 26 may have an aperture into which the end of the reinforcing 32 is received. Alternatively, the reinforcing 32 may be welded to the end of the reinforcing mount 26. The reinforcing shown in Figure 6 is bent but any shape is permissible.

Figures 7 to 9 illustrate an alternative embodiment in which the reinforcing mounts 26 are provided both in the side wall 12 and in the top flange 14. Figure 10 illustrates a portion of a slab 18 which has its external periphery bordered by sacrificial form work 10. Specifically, there are four pieces which define four respective sides of the portion of the slab 18. The pieces have mitred joints where they meet at the corners. Alternatively, the sections may have a square cut end on one section and the top and bottom flange removed from the adjoining section. The sections may be welded together or joined by tabs, which are secured by fasteners.

Figure 11 illustrates the sixth embodiment of the present invention in which the reinforcing mounts 26 are provided at the top flange 14 of the channel section. This provides a mounting for the superstructure 40 on the top surface of the slab 18 as illustrated. The superstructure 14 may comprise a balcony railing. In the seventh embodiment of Figure 12, there are two rows of reinforcing mounts 26 providing attachment for the superstructure 40 at the side wall 12.

Figure 13A is similar to Figure 1 1 in that it provides for mounting of the superstructure 40 on the top of the slab 18. In this version, the bolt 28 can be seen. Figure 13B is similar to Figure 12 in that it provides for mounting of the superstructure 40 to the side wall 12. However, there is only one row of reinforcing mounts 26.

Figure 14 is similar to the embodiment of Figure 12 in that it provides for mounting of the superstructure 40 to the side wall 12. In this particular case, the superstructure 40 is a bracket which may be used for mounting another item onto the slab 18.

The foregoing only describes some embodiments of the present invention and modifications may be made thereto without departing from the scope of the present invention .

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

Claims

1. Formwork for a concrete construction, the formwork including: at least one section to define at least part of an edge or side of the concrete construction; and a plurality of reinforcing mounts provided on the at least one section for mounting concrete reinforcing, wherein said reinforcing mounts are each engageable with a fastener for attaching a superstructure to the concrete construction.

2. The formwork as claimed in claim 1 wherein the section includes a side wall to define a side of the concrete construction and a top wall or flange and a bottom wall or flange.

3. The formwork as claimed in claim 1 or claim 2 w^rherein the section defines an internal region for concrete flow to envelop the reinforcing mounts, the reinforcing mounts being positioned within the internal region.

4. The formwork as claimed in any one of the preceding claims wherein the section is a channel.

5. The formwork as claimed in claim 4 wherein the channel includes a return from the top flange and a return from the bottom flange.

6. The formwork as claimed in claim 5 wherein the channel defines an internal region for concrete flow to envelop the reinforcing mounts and the returns, the returns extending into the internal region.

7. The formwork as claimed in any one of the preceding claims wherein the reinforcing mounts are in the form of short cylindrical members.

8. The formwork as claimed in claim 2 wherein the reinforcing mounts are provided to extend from the side wall of the section or from the underside of the top wall or from the upper side of the bottom wall.

9. The formwork as claimed in any one of the preceding claims wherein the reinforcing mounts each have an internally threaded bore which aligns with a hole in the section to permit passage of said fastener, the reinforcing mounts being secured to the section by said fastener or a temporary fastener, the location of the reinforcing mounts and the holes being predetermined to align with parts of the superstructure.

10. The formwork as claimed in any one of the preceding claims wherein the reinforcing mounts include aligned through-holes for insertion of a reinforcing bar therethrough.

11. A concrete slab construction including the formwork as claimed in any one of the preceding claims.

12. A building construction including the concrete slab construction as claimed in claim 1 1 and further including a superstructure attached to the formwork, wherein the superstructure is attached to the slab by the use of said fasteners.

13. The building construction as claimed in claim 12 wherein the concrete slab construction includes a balcony portion and a plurality of such formwork sections are joined to define the outer periphery of the balcony portion and wherein the remaining portion of the floor slab uses conventional formwork.

14. A method of concrete construction comprising: providing formwork to define a concrete construction, the formwork including at least one section to define at least part of an edge or side of the concrete construction, the at least one section including a plurality of reinforcing mounts wherein each of said reinforcing mounts is engageable with a fastener for attaching a superstructure to the concrete construction; and mounting reinforcing to the reinforcing mounts.

15. The method as claimed in claim 14 wherein the reinforcing mounts are secured to the section by fasteners and the method further comprises: pouring concrete and allowing the concrete to set and form a permanent bond to the section and the reinforcing mounts; and attaching a superstructure to the concrete construction by using said fasteners or alternatively, other appropriate grade fasteners.

16. Formwork for cast concrete constructions including: a section of sheet metal formwork, the section defining an internal region for concrete flow and an external region to define at least part of an edge or side of the concrete construction, with a plurality of holes in predetermined locations in a wall of the section; a reinforcing mount positionable at each of said holes in said internal region, wherein said reinforcing mount is engageable with a fastener for attaching a superstructure to the concrete construction.

17. The formwork as claimed in claim 16 wherein said fastener or a temporary fastener is positioned through each of the holes in the section to be received in the associated reinforcing mount to hold the reinforcing mount in position in the internal region.

18. The formwork as claimed in claim 16 or 17 wherein the section includes a side wall to define a side of the concrete construction and a top wall or flange and a bottom wall or flange.

19. The formwork as claimed in claim 18 wherein the section is a channel and the channel includes a return from the top flange and a return from the bottom flange.

20. The formwork as claimed in claim 18 wherein the reinforcing mounts are provided to extend from the side wall of the section or from the underside of the top flange or from the upper side of the bottom flange.

21. The formwork as claimed in any one of the preceding claims wherein the reinforcing mounts each have an internally threaded bore which aligns with a respective one of the holes in the section to permit passage of said fastener.

22. A concrete slab construction including the formwork as claimed in any one of claims 16 to 21.

23. A building construction including the concrete slab construction as claimed in claim 22 and further including a superstructure attached to the formwork, wherein the superstructure is attached to the slab^' by the use of said fasteners which engage with the reinforcing mounts.

24. The building construction as claimed in claim 23 wherein the concrete slab construction includes a balcony portion and a plurality of such formwork sections are joined to define the outer periphery of the balcony portion and wherein the remaining portion of the floor slab uses conventional formwork.

25. A method of forming formwork for cast concrete constructions, the method including: forming from sheet metal, a section defining an internal region and an external region to define at least part of an edge or side of the concrete construction, with a plurality of holes in predetermined locations in a wall of the section; and at each of said holes, positioning a reinforcing mount in said internal region, wherein said reinforcing mount is engageable with a fastener for attaching a superstructure to the concrete construction.

26. The method as claimed in claim 25 wherein the section is formed from sheet metal by initially cutting to size and forming the holes by punching, laser cutting or any other appropriate means and subsequently shaping the sheet metal in a press, folder or roll forming machine.

27. The method as claimed in claim 25 or 26 wherein each reinforcing mount is positioned prior to concrete pour by said fastener or a temporary fastener inserted through the hole to engage with the reinforcing mount.

28. The method as claimed in any one of claims 25 to 27 wherein the method- further includes locating and/or securing reinforcing in the reinforcing mounts.

29. The method as claimed in any one of claims 25 to 28 further including pouring concrete so that the concrete flows into the internal region and envelops the reinforcing mounts.

30. The method as claimed in claim 29 further including removing each of the fasteners or said temporary fasteners and attaching the superstructure by inserting said fasteners through the superstructure and into engagement with the reinforcing mounts.