USING SAME

FIELD OF THE INVENTION

[0001] The present invention relates to a reinforcement connector for a form panel and related systems for building concrete filled reinforced structural elements such as walls, columns and beams. In particular, it relates to systems where removable, and ideally, re-useable form panels are used as the external components of the formwork to define the outside surfaces of the finished element.

[0002] The invention has been developed primarily for use in offsite prefabrication of structural forms for building elements such as steel reinforced concrete walls and columns and will be described herein with reference to this preferred use. However, it will be appreciated by those skilled in the art that the invention may also be suited for use in constructing formwork structures for steel reinforced structural forms that are fabricated on site.

BACKGROUND TO THE INVENTION

[0003] Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

[0004] Lost formwork methods of construction, where the form panels remain in place and become part of the finished structure, are widely used in the building industry for forming structural load bearing walls and columns and the like. Such systems typically include a number of panels that define the external surfaces of the form, with an arrangement of steel reinforcing elements disposed within the form. In most heavy load bearing applications, the reinforcing elements are supported and/or tied together into a three-dimensional arrangement. This arrangement of reinforcing elements is ideally disposed a predetermined distance from the external panels, to ensure adequate and even concrete coverage of the steel reinforcement after the concrete has been poured into the form.

[0005] One of the biggest challenges in structures of this kind is ensuring that the formwork panels are supported to resist the hydrostatic pressures applied by the wet concrete during the pour and prior to the concrete curing, while at the same time ensuring that the reinforcing elements remain in their designed location. This is particularly relevant in tall structures like walls and columns where the head of flowable concrete creates significant pressure against the formwork panel cladding.

[0006] While external bracing may be used in some applications, this is dependent on the nature of the structure to which the form is to be secured and reliance on external bracing doesn’t help facilitate offsite prefabrication.

[0007] Most commonly in wall and column structures, removable tensile tie elements in the form of long bolts (generally known as “Z-bars”) are used that extend through conduits that pass through the reinforcing and opposing cladding panels and are secured by external fasteners against the external surfaces of the formwork cladding panels. Where needed, internal spacers are disposed between the reinforcing elements and the panels to position the reinforcement and panels in their designed locations, which are secured in place by the tensile forces applied by the tie elements. This method is time consuming and results in a number of holes in the finished concrete structure which need to be patched and finished.

[0008] An improvement was proposed by the Applicant in WO2016/061627 which describes, in one embodiment, the use of tensile ties in the form of high strength flexible strapping, which results in a lighter structure and an outer surface that is much easier to finish, as the strapping is easily covered over with further cladding or simply cut and removed. It also readily facilitates off-site prefabrication of forms pre-loaded with correctly positioned reinforcement. However, there is still a need to provide openings in the formwork cladding panels to receive the tensile ties and once again forming the holes and securing the ties is still relatively labour intensive.

[0009] Further improvements were proposed by the Applicant in WO2017/201577 which included a two-part connector having an internal part and an external part, which easily snapped together to secure to the cladding in between, but again this requires openings to be provided in the cladding. While another alternative embodiment was proposed that secured at one end to the reinforcement and at the other to the inner surface of the cladding, the need to screw and/or glue or otherwise secure the connector flanges to the inner surface of the cladding was time consuming.

[0010] Additional improvements were proposed by the Applicant in WO2019/14825 whereby specially configured form panels are used that include some form of dovetail slot or t-slot formations at spaced intervals. Specialist clips are then used to snap on, at a first end, to the internal reinforcement cage. The second end of the clips include t-formations or dovetail formations that correspond with those provided in the panels. In that way, the clips can be pre attached to the reinforcement cage and the panels slid over the second end formations, preventing separation of the panel from the clips under loads applied along the length of the clip. In this way the clips hold the panels in place during the concrete pour and post construction.

[0011] There are also other systems that obviate the requirement for drilling through holes and inserting tie elements, by providing rigid internal web elements of metal, plastic or other suitable materials that extend between opposing formwork cladding panels. However, these rigid web elements take up a lot of internal space and often section the void internally, thereby reducing the space available for the reinforcing and limiting the design to certain structures. For example, in Australia, use of systems of this kind are limited to structures classified as walls as defined by the relevant concrete design code AS3600. The rigid web elements in these systems can also inhibit the concrete flow and access to the reinforcement during the concrete pour making it difficult to ensure the structural integrity of the final form.

[0012] While the lost formwork systems described above have worked well, and have provided the benefits of enabling off-site prefabrication, it is now becoming increasingly desirable to provide a labour saving pre-fabricated formwork system where the form panels can be removed post construction to inspect and approve the finished concrete and reinforcement structure. It is also desirable to provide systems which readily enable re-use of materials to reduce waste.

[0013] It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

SUMMARY OF THE INVENTION

[0014] According to one general aspect of the invention there is provided a connector for securing a formwork panel or intermediate component at a fixed distance from a reinforcement element, the connector including: a compression resistant spacer having a first end and a second end defining a spacer depth there between; first connection means being provided at the first end for releasably securing the connector to the formwork panel or intermediate component; and second connection means being provided at the second end for securing the connector to the reinforcement element. [0015] The reference to reinforcing element used herein includes reference to any reinforcement bar element and includes, horizontal bar elements or tie elements commonly referred to as ligatures.

[0016] Preferably the connector is made of a polymeric material and more preferably from a tough but not brittle material such as HDPE, PVC, Nylon, or any other suitable polymer.

[0017] According to a first aspect of the invention, there is provided a connector for securing a formwork panel at a fixed distance from a reinforcement element, the connector including: a compression resistant spacer and tensile tie element having a first end and a second end defining a spacer depth there between; first connection means being provided at said first end for releasably securing the connector to the formwork panel or intermediate component; and second connection means being provided at the second end for securing the connector to said reinforcement element; wherein the first connection means comprises a panel abutment surface to bear against an adjacent form panel and a fastener receiving region adapted to retainingly receive a releasable fastener applied through an opening in an adjacent form panel placed against the abutment surface.

[0018] In a preferred form, the fastener is a threaded fastener, preferably with a head formation at one end and a surface engaging formation at the other, such as is provided by a bolt or screw, and the fastener receiving region is formed to receive and engage the surface engaging end of the fastener. Preferably, the fastener receiving region is in the form of a metal insert.

[0019] In one such embodiment, the fastener is in the form of a tek type screw and the fastener receiving region is adapted to receive the threaded end of the screw. The tek type screw may be a self-drilling and/or may be a self -tapping.

[0020] In one preferred embodiment, the connector is made of a polymeric material and a metal insert is provided in the form of a metal sheet which is penetrable by the threaded end of the self-drilling screw. The insert may be integrally moulded into the connector during moulding or added to the connector post moulding and/or post connection to the reinforcement element. [0021] In another embodiment the fastener is in the form of a bolt. In one form the receiving region is formed within the body material of the connector itself. This region is in the form of a threaded hole. In another form, the region is formed by a threaded insert which could be in the form of a nut. Preferably, a guide formation is also provided adjacent the fastener receiving portion to assist in guiding the surface engaging formation end of the bolt into the threaded hole or nut. The guide may comprise some form of tapering formation such as a conical formation.

[0022] According one embodiment, the compression resistant spacer of the above connectors includes a first part and a second part. Preferably, the first part is slidably engageable with the second part. More preferably, the first part includes one or more dovetail tabs for sliding complementary engagement with corresponding dovetailed apertures in the second part.

[0023] According to a second aspect of the invention there is provided a method of constructing a reinforced concrete structure using the connector of the first aspect of the invention, the method comprising the steps of: selecting a reinforcement structure including a reinforcement element; securing the second end of at least one connector to the reinforcement element; releasably securing at least one formwork panel to the first end of the at least one connector by means of a fastener applied through the formwork panel and completing the form; pouring concrete into the form and allowing the concrete to solidify; and removing the formwork panel by releasing the panel from the first end of the connector by removing the fastener.

[0024] In some embodiments where a metal insert is used to receive the end of the screws or bolts, the method may include the step of inserting the metal insert into the connector after securing the second end to the reinforcement element.

[0025] In one embodiment which uses self-drilling and self-tapping screws, the screws can be screwed directly through the panel and in to the second end of the connectors, which ends may include a metal insert to receive and retain the screws.

[0026] In other embodiments that use fasteners in the form of bolts, holes are pre-drilled in the panels through which the fasteners can be inserted to engage the threaded holes in the second ends of the connectors. The pre-drilled panels can also be used as templates for marking the reinforcement to determine the correct location and spacing prior to assembly. [0027] According to a third aspect of the invention there is provided a formwork system including: a form panel; a reinforcement element; a connector according to the general aspect of the invention configured for securing to an intermediate element to be located between the connector and the form panel; wherein the intermediate element is configured for releasable connection with the form panel.

[0028] Preferably, the intermediate element includes a channel type formation which engages with the connector by means of a complementary formation provided on the first end of the connector that is slidably receivable within the channel but cannot be removed from the channel in a direction transverse to the direction of sliding. In one form, the intermediate element may be a simple c-section channel element and the first end of the connector includes formations that extend outwardly so as to slide within the channel but be held captive under a transvers load as applied along the spacer depth of the connector.

[0029] In a preferred form the intermediate element is adapted for releasable connection with the form panel by means of self-drilling screws or similar fasteners applied from an outer surface of the form panel.

[0030] According to a fourth aspect of the invention there is provided a method of constructing a reinforcement and formwork panel assembly using the formwork system of the third aspect of the invention comprising the steps of: selecting a reinforcement structure including a reinforcement element; securing the second end of at one connector to the reinforcement element; securing an intermediate element to the first end of said connector; releasably securing at least one formwork panel to the intermediate element and completing the form; pouring concrete into the form and allowing the concrete to solidify; and removing the formwork panel by releasing the panel from the intermediate element which remains captive in the structure.

[0031] The reinforcement element may form part of a prefabricated reinforcement cage, or other reinforcement configuration including secured bar or mesh. [0032] Preferably, the connector is generally longitudinal, extending in a longitudinal direction generally transverse to the spacer depth to align with a length of reinforcing rod. In one preferred form, the compression resistant spacer is in the form of a spacer web.

[0033] In one preferred form, the connector is a single piece structure preferably made of a suitable polymeric material that has two opposing halves configured to resiliency deform about its second end where a reinforcing rod retention formation is provided, so that it can be opened up and placed over a reinforcing rod from a side remote from the formwork panel to which it is to be secured. At a location between the rod receiving second end of the connector and the second connection formations at the opposite end, catch formations are provided, one on each half, to thereby secure the connector in a closed position to the reinforcing rod. The catch formations can again be of any suitable configuration, but this time configured to retain the two connected halves of the connector together in a direction transverse to the spacer depth and the reinforcing rod retention means. In one form this is achieved by provision of interacting resiliency deformable hook or barb arrangements provided on each half, which deform as the two parts are bought together and then snap into inter- locking engagement to secure the connector.

[0034] In this same embodiment, the distal ends of the two opposing halves of the connector form flanges which extend longitudinally outwardly from the top to form protruding slide formations which are configured to slidingly engage corresponding channel formations provided on the intermediate element. The slide formations may be continuous along the longitudinal length of the connector, corresponding to the longitudinal extent of a reinforcing rod, or more preferably may be in the form of two opposing L formations that define an intermediate gap to accommodate a formwork panel join or fastener receiving insert as described below. In this manner, one connector design can be configured for multiple different connection methods.

[0035] The shape of the reinforcing rod receiving means may be arcuate to conform closely to an adjacent portion of the circular periphery of the reinforcing rod, or may include flat regions or resilient finger formations. In one particularly preferred form, the mould for producing the connector is configured to produce a connector that will closely fit the largest diameter commonly used reinforcement rods, and mould inserts are provided that can be used to tailor the connectors for smaller diameter rods by defining finger formations that extend radially inwardly to grip the smaller rods. [0036] According to a fifth aspect of the invention there is provided a connector wherein the second connection means for securing the connector to the reinforcement element comprises a closed aperture extending through the second end of the connector.

[0037] In one preferred form, the connector is made from a simple length of bar, with one end of the bar defining the first end for releasably securing to the formwork panel, and a through aperture is provided adjacent the other end second end to receive a reinforcement element there through.

[0038] In one preferred form, the bar has a simple square or rectangular cross-section of sufficient size to provide the required tensile and compressive strength after accommodating the through aperture for the reinforcement element. Desirably, a channel is also provided through the centre region of the first end to allow concrete flow around the securing fastener in use and minimise the area of exposed connector material after the formwork has been removed. In one preferred form the bar is made from plastic with a 30mm by 30mm square cross-section. Securing of the panels to the first end of the bar is by self-tapping tek type screws or similar as discussed herein.

[0039] According to a sixth aspect of the invention there is provided a method of manufacturing a connector according to the fifth aspect of the invention including the steps of: cutting a suitable length of bar material; and drilling a through hole at the second end to suit the reinforcement element material it is to be used with.

[0040] Preferably the method includes the additional step of providing a channel across the surface of the first end. In one preferred form, this is achieved by drilling spaced holes along a length of bar and cutting the bar through one of said holes to form the firs end with a u-shaped half cylinder channel extending across same.

[0041] It will be appreciated that connectors according to the fifth aspect of the invention cannot be clipped onto a closed reinforcement element such as a cage after the cage has been constructed but must instead be slid on to the reinforcement elements during manufacture of the cage.

[0042] For example, a typical cage structure for a wall type construction, will include two parallel sheets of reinforcement elements welded together into a two-dimensional orthogonal grid, most usually comprised of multiple parallel vertical and horizontal reinforcement elements, with the two sheets spaced from each other and retained by further tie elements that extend transversely between the two sheets. In other cage structures the tie elements may bound the sheets and be integrally formed with say the horizontal reinforcement elements to extend across and between the sheets.

[0043] According to a seventh aspect of the invention there is provided a method of a method of constructing a pre-fabricated reinforced concrete form using the connector of the fifth aspect of the invention, the method comprising the steps of; constructing a reinforcement element structure wherein connectors of the fifth aspect of the invention are slid into selected positions on the cage to extend outwardly therefrom during construction; and releasably securing at least one formwork panel to the first end of the connectors by means of a fastener applied through the formwork panel to each connector.

[0044] According to an eighth aspect of the invention there is provided a method of a method of constructing a pre-fabricated reinforced concrete structure using the connector of the fifth aspect of the invention, the method comprising the steps of constructing a pre-fabricated reinforced concrete form according to the seventh aspect of the invention;

Installing the form on site and completing same; pouring concrete into the form and allowing the concrete to solidify; and removing the formwork panel or panels by releasing the panel or panels from the first end of each connector by removing the associated fastener.

[0045] According to a ninth aspect of the invention there is provided a dual function connector that also acts as a cage tie element as described above, wherein the bar has two opposing first ends and two spaced through apertures between the two first ends for securing to spaced reinforcement elements, the length of bar extending between the through apertures serving as tie elements between the spaced reinforcement elements.

[0046] The connectors may be made from suitable polymeric materials which include high density polyethylene (HDPE), polypropylene and nylon, but other suitable plastics materials may also be used which may include polycarbonate. Preferably the material will be suitable for CNC machining, injection moulding or extrusion (as required), have a tensile yield strength of at least 30Mpa, a flexural strength of at least 30Mpa and a suitable impact toughness. [0047] Preferably, the form panels are made from a material that enables multiple re-use to minimise wastage and cost. Suitable materials may include plywood and/or polymeric materials. Where polymeric materials are used, the panels may optionally be at least partially transparent or translucent whereby it is possible to view some or all of the concrete after, or as it is being, poured into the form. Subject to the material and form of the form panels, the use of some form of releasing agent may be needed to assist in removal of the panels and minimise clean up required for re-use.

[0048] In one form the panels are made from a polycarbonate material which is ideally at least partially translucent and which may include rib formations to provide increased stiffness and strength which may also contribute to increased life if designed to be re-used.

[0049] Reference throughout this specification to “one embodiment”, “some embodiments” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment”, “in some embodiments” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Preferred embodiments of the invention will now be described, by way of example only, with reference to the following drawings in which:

[0051] Figure 1 is a front view of a first embodiment connector according to a first aspect of the invention shown in situ between a form panel and reinforcing element;

[0052] Figure 2 side view of the connector assembly shown in Figure 1 ;

[0053] Figure 3 is a front view of a second embodiment connector according to a first aspect of the invention shown in situ between a form panel and reinforcing element;

[0054] Figure 4 is a side view of the connector assembly shown in Figure 2; [0055] Figure 5 is a front view of the elements of a formwork system according to a first embodiment of the third aspect of the invention;

[0056] Figure 6 is side view of the system shown in Figure 5;

[0057] Figure 7 is a perspective view illustrating partial assembly of the formwork for a wall structure using the system shown in Figures 5 and 6;

[0058] Figure 8 is a perspective view of the completed formwork for the wall assembly;

[0059] Figure 9 is a front view of the completed wall assembly of Figures 8 and 9 once the external form panels have been removed;

[0060] Figure 10 is a front view of a third embodiment connector according to the first aspect of the invention illustrating an alternative means for securing the clip around the reinforcement element;

[0061 ] Figure 11 is a side view of the embodiment shown in Figure 10;

[0062] Figure 12 is a schematic perspective view of a reinforcement structure for a wall illustrating potential locations of connectors according to the fifth aspect of the invention;

[0063] Figure 13 is a sectional side view and part sectioned front view of a first embodiment connector according to the fifth aspect of the invention;

[0064] Figure 14 is a part sectioned front view and sectional side view of a first embodiment dual function connector in accordance with the ninth aspect of the invention;

[0065] Figure 15 is a sectional front view of a two-part connector shown in situ between a form panel and reinforcing element in accordance with a further embodiment on the invention;

[0066] Figure 16 is a sectional side view of a two-part connector of Figure 15; and

[0067] Figure 17 is sectional front and side view of each part of the two-part connector of Figure 15. DESCRIPTION OF PREFERRED EMBODIMENTS

[0068] Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the drawings, the same elements are denoted by the same reference numerals throughout. In the following description, detailed descriptions of known functions and configurations incorporated herein have been omitted for conciseness and clarity.

[0069] Referring to Figures 1 and 2 there is shown a first embodiment connector 1 according to a first aspect of the invention shown in situ between a form panel 2 and reinforcing element in the form of reinforcement rod 3. The connector 1 includes a compression resistant spacer and tensile tie element shown generally at 4. The tie element has a first end 5 and a second end 6 and defines a spacer depth there between.

[0070] In the majority of preferred forms, the connector is made from a high strength moulded polymeric material such as polycarbonate, nylon or polypropylene.

[0071] First panel connection means are provided at the first end 5. In this particular embodiment, the panel connection means includes a panel abutment surface 7 for bearing against the inside surface 8 of the adjacent form panel 2, and a fastener receiving region shown generally at 9 which is adapted to receive a releasable fastener 10 applied through an opening 11 provided or created in the form panel 2.

[0072] The releasable fastener 10 in this embodiment is in the form of a self-drilling and self tapping tek type screw with a head 13 and threaded region 14 and the fastener receiving region is formed by a high strength insert 15. The insert can be added to the connector after moulding or during the moulding process. Preferably the insert is metal and sufficiently strong to resist pull out when tensile forces are applied. In one example the insert is a steel strip of approximately 50mm length, 25mm width and thickness of around 3mm. One suitable type of tek screw is such as those supplied by Masbolt™ 10 to 12 gauge and 35 to 45mm long, part number 23HB1235.

[0073] The compression resistant spacer element and tensile tie 4 of this embodiment and that shown in Figures 3 to 9 is in the form of opposing webs 17 that also define the panel abutment surface or surfaces 7 at the first end of the connector. The webs 17 are resiliently connected at the second end 6 to form a reinforcing rod retention means in the form of an openable contoured region 18 that has inwardly directed stop formations shown at 19. [0074] The connector 1 also includes catch means 20 for securing the hinged halves of the connector about the reinforcement rod 3. In the illustrated embodiment these are in the form of opposing resiliently deformable hook or barb extensions 21 provided on an inner surface of each web. These barbs 21 deform in a transverse direction as the two parts are bought together and then snap into inter-locking engagement to secure the connector 1 to the rod 3. In the illustrated embodiment, one barb extends outwardly and downwardly, and the other extends outwardly and upwardly.

[0075] The illustrated connector also includes additional formations at the first end 5 which will enable the connector to be used in a different panel connection configuration as will be described in more detail in relation to the second embodiment shown and described in relation to Figures 5 to 9. These formations are not relevant to the connection means described in relation to the first and second embodiment of the first aspect of the invention.

[0076] In use, a reinforced concrete structure can be constructed using the first embodiment connector 1 as follows. Firstly, the reinforcement elements are secured to each other as needed. In most embodiments, the reinforcement elements will be joined in the form of a pre-fabricated cage which are bound by ligatures which will be the reinforcement rod 3 shown in the drawings. The connectors 1 are then secured to these ligatures at predetermined spacing by pulling open the two resilient webs 17, feeding the clip about the rod 3 until it is seated within the contoured region 18 and then clipping the connector halves together by forcing the webs toward each other until the deformable barbs 21 are driven apart from each other and then snap back in place to retain the two webs as best shown in Figure 2. At that point the connector will be securely held to the rod 3 which is retained at that second end 6 by means of the stop formations 19 contacting the ligatures. In the illustrated embodiment, the metal insert 15 is then slid into a channel formed in the clip so that it is captive as shown.

[0077] Once the connectors 1 have all been attached to the ligatures, the form panel 2 can be aligned such that the panel abutting formations 7 bear against the inside surface 8 and the self-drilling self-tapping screws 10 can be driven through from the opposite side of the panel and into the fastener receiving region 9 and into the metal insert 15. The panels 2 can be made of any suitable material that can be removed post curing such as plywood or a polymeric material. In one form, the panel is made from translucent polycarbonate enabling flow of the concrete within the form to be viewed during construction. [0078] Once all the formwork has been erected and the concrete has been poured and has cured sufficiently to hold its form, the fasteners can be unscrewed while the concrete is still green and the form panels 2 can be removed. In this manner, the concrete can be readily inspected and the form panels can be re-used multiple times, depending on the material. The only finishing required will be to patch the small holes around the fastener receiving regions of the connectors.

[0079] Turning next to Figures 3 and 4 there is shown a second embodiment connector T according to the first aspect of the invention and like reference numerals will be used to denote corresponding features.

[0080] The essential difference between this second embodiment and the first embodiment of Figures 1 and 2, lies in the form of the fastener 10’ and receiving region 9. In this embodiment of the connector T, the fastener 10’ is in the form of a bolt designed to screw directly into an aperture 22 in the material of the connector. In this embodiment this region of the connector is built up to provide more material to receive and hold the end of the fastener.

[0081] While the illustrated embodiment has a similar profile to that shown in Figures 1 and 2 and uses the same two-part hinged structure that snaps together, it is envisaged that future embodiments may have a larger fastener receiving region 9 to enable a more secure hold on the fastener and reduce the alignment tolerances needed to ensure the fastener is adequately surrounded by connector material. For example, the abutment region 7 may be larger and wider than the form illustrated in Figures 3 and 4. The aperture 22 may be pre-formed and pre threaded and include a tapered guide region 12 as shown. Flowever, in other variations, the threaded hole may be defined by a threaded insert such as a nut. The nut could be incorporated into the connector during moulding or manually inserted post production or during the connector installation process.

[0082] In yet further variations it may be possible to use special self-drilling and tapping screws that will work with the plastic material of the connector such that minimal if any pre forming is required. In this way it will operate in a similar way to the first embodiment but obviate the need for a metal insert.

[0083] In the illustrated form of the second embodiment that uses a bolt as the fastener, the form panel 2 will have pre-drilled holes that correspond to the desired spacing on the reinforcement rods 3 as determined by the structure of pre-fabricated the reinforcement cage. To help determine the corresponding location on the reinforcement cage, the panel can be positioned as required and spray paint or other suitable marking material can be used to mark the rod locations by marking through the panel holes.

[0084] Turning next to Figures 5 to 9 there is shown a first embodiment of a formwork system according to a first embodiment of the third aspect of the invention and again like reference numerals will be used to denote corresponding features.

[0085] This embodiment varies from those that use the connector of the first aspect of the invention in that the connector does not connect directly to the form panel by releasable fasteners. Instead, the connectors 1” firstly connect to an intermediate member which is to be located between the connector 1” and the form panel 2. In this particular embodiment, the intermediate member is in the form of a c-shaped channel 25. The channel 25 has a panel engaging surface 26, sides 27 and return edges 28 as shown.

[0086] In order for the connector 1” to secure to the channel, the first end 5 incorporates an overall T shaped profile formed by opposing formations 29 which each includes longitudinally outwardly extending L shaped formations with indents 30 that are configured to slidingly seat around the channel return edges 28. As can be seen from Figure 6 the opposing formations 29 preferably taper outwardly towards the end 5 to increase width and maximise the amount of material at the connection end and thereby enhance the holding capability of the connector 1”.

[0087] Referring in particular to Figures 7 to 9 the method of construction is as follows. Firstly, the reinforcement is preferably in the form of a pre-fabricated cage structure 35 bound by ligatures or some other tie system connecting the two layers of reinforcement. In this case, the connectors 1” are secured to horizontal bars 36 on the cage as described in relation to the embodiment of Figures 1 to 4 whereby they are vertically aligned as required.

[0088] Once the connectors 1” are secured, the channels 25 are slid over the connectors which then form a series of spaced beams to which the panels 2 can be secured. Preferably this is done by use of self-drilling metal screws 13 that can be screwed in from the outside of the panels and into the panel engaging surface 26 (See Figure 5).

[0089] Once all the panels have been secured to define the full form, the concrete can be poured. After the concrete has been sufficiently cured, the panels can then be removed by simply unscrewing the screws that connect to the channels and the completed structure retains the channels 25 as shown in Figure 9. While the channels may be polymeric or metal or indeed any suitable material, if the connectors are polymeric, the use of metal channels is fine as there is no metal extending from adjacent the outer surface to the cage, the connectors acting as a non-corrodible insulator that protects the embedded reinforcement.

[0090] While the embodiments illustrated in relation to Figures 1 to 9 all show an interacting barb connection system for snapping and retaining the connector in place about the ligature/reinforcement element 3, an alternative securing arrangement is shown in the connector 1 in Figures 10 and 11 . The basic shape is very similar, but the two webs 17’ do not have any barbs, but instead have grooves 38 which slidingly receive a u-shaped connector 39 that once inserted, retains the two webs in a connected orientation as shown.

[0091] The formwork system of the third aspect of the invention offers significant advantages over the prior art by enabling simple pre-fabrication of forms and reinforcement when needed, whilst still enabling removal of the form panels to inspect the formed concrete structure and enable re-use of the form panels. Post forming surface finishing is also minimised. Additionally, the optional use of translucent panels enables assessment of the quality of the structure and successful vibration of the concrete during the construction process. There are also significant cost savings over lost formwork systems in that the cost of material left in the structure is limited to the intermediate elements rather than whole panels.

[0092] The formwork system of the first and second aspects of the invention offer the additional significant advantage of still enabling simple pre-fabrication and re-use of panels, whilst reducing the cost of components lost to the finished structure to the cost of the connectors.

[0093] The connectors of all embodiments may be made from suitable polymeric materials which include polycarbonate, polypropylene and nylon, but other plastics materials can also be used. Preferably the material will be suitable for injection moulding or extrusion, have a tensile yield strength of at least 30Mpa, a flexural strength of at least 30Mpa and a suitable impact toughness.

[0094] In a preferred form, the connectors are injection moulded from ‘nylon 6’, have a length of about 65mm at the panel engaging end and 25mm at the reinforcing rod engaging end.

[0095] Preferably, the design of the connector is optimised for a short moulding cycle to minimise production cost by incorporating web like structures to avoid thick regions of material which will be slow to set. [0096] Preferably, the form panels are made from a material that enables multiple re-use to minimise wastage and cost. Suitable materials may include plywood and/or polymeric materials. Where polymeric materials are used, the panels may optionally be at least partially transparent or translucent whereby it is possible to view some or all of the concrete after or as it is being poured into the form. Subject to the material and form of the form panels, the use of some form of releasing agent may be needed to assist in removal of the panels and minimise clean up required for re-use.

[0097] In one form the panels are made from a polycarbonate material which is ideally at least partially translucent, and which may include rib formations to provide increased stiffness and strength which may also contribute to increased life if designed to be re-used. Wherever possible, it is preferable that recycled polymeric materials be used.

[0098] While the embodiments of connectors illustrated in Figures 1 to 11 are generally longitudinal to extend along a reinforcement element, this is not essential and could be proportionally shorter or longer or of different peripheral shape, so long as the rod engagement means securely attaches to the reinforcing elements, the spacer element operates to space and retain the rod element from the formwork panel, and the panel engagement means form a strong connection with the associated formwork panels.

[0099] Similarly, while the connector embodiments described in Figures 1 to 11 use an arrangement with two opposing arms or webs to secure to the reinforcement rods, this is not essential and could be varied. For example, the connector could include rod retention means in the form of an open end with two resilient curved arms that can deform by push fit over the ligature to form the connection to the reinforcement, and the panel engaging formations extend at the opposite end, with a single interconnecting web formation in between.

[00100] In another form, the rod retention means could be openable and snap back or otherwise secure to a web extending between the two ends, such that no split is provided at the panel engaging or intermediate element engaging end. This may be particularly advantageous for the embodiments of the first aspect of the invention where a continuous mass of connector material may enable a more secure fastener receiving region.

[00101] Flaving particular regard to connectors of the first aspect of the invention that are configured to secure directly to the form panels, variations to the design are anticipated to enable post production adjustment of the offset length of the connector, to allow for variations in the reinforcement elements and structures. One such variation is the replacement of the flat panel abutment surfaces 7 with a plurality of finger like formations that could readily be cut down as needed to shorten the connector offset length.

[00102] It will also be appreciated that while one particular arrangement has been disclosed in relation to the embodiment described in Figures 5 to 9 relating to the third aspect of the invention by which the distal ends of the connectors lockingly engage the selected channel elements, other interlocking configurations that avoid the need for separate fasteners or adhesives could also be used. For example, the ends of the connectors could include a T-shaped or dovetailed aperture adapted to receive correspondingly configured protruding formations formed on an alternative intermediate element to the channel. Other conventional press fit, key hole or cam type interactions could also be used.

[00103] T urning next to Figures 12 to 14 there are shown further embodiment connectors that are designed to be secured to a reinforcement structure, such as that shown schematically in Figure 12, during manufacture of that structure. The advantage of these connectors is that they are simple to produce and very strong.

[00104] A preferred embodiment connector 40 according to the fifth aspect of the invention is shown in the two views of Figure 13. Where convenient, like reference numerals have been used to denote corresponding features.

[00105] This embodiment differs most significantly from the prior embodiments by the form of the second connection means for securing the connector 40 to the form panels 2. In this regard, the connector is no longer in the form of a clip type arrangement that can be opened up into two pivotably connected arms that can re-join to secure over a reinforcement bar, but instead connects to the ligature or reinforcement element via a suitably sized closed through aperture 41 located at the second end. Typical aperture sizes would be selected to suit reinforcement bars having diameters or 10/12/16/20mm diameter. The aperture will ideally be sized to suit the reinforcement rod 3 to which it is to be secured, such that there is frictional engagement enabling the connector to be moved into the required position and be retained in that position. This may be by means of an interference fit or other suitable means.

[00106] In one preferred form, the connector is made from a simple length of bar, with one end of the bar defining the first end 5 for releasably securing to the formwork panel, and a through aperture is provided adjacent the other end second end to receive a reinforcement element there through.

[00107] In one particularly preferred form, the bar has a simple square or rectangular cross- section of sufficient size to provide the required tensile and compressive strength after accommodating the through aperture for the reinforcement element. Desirably, a channel 42 is also provided through the centre region of the first end to allow concrete flow around the securing fastener in use and minimise the area of exposed connector material after the formwork has been removed. For example, in the illustrated embodiment, only two spaced parallel strips of plastic at the first end 5 will be visible once the form panels have been removed. In one preferred form the bar is made from plastic with a 30mm by 30mm square cross-section. Securing of the panels to the first end of the bar is by suitable fasteners 10 such as self-tapping tek type screws or similar screws designed specifically for use with plastics.

[00108] One method of manufacturing a connector 40 includes the steps of: cutting a suitable length of bar material; and drilling a through hole 41 at the second end 6 to suit the reinforcement element material it is to be used with.

[00109] Preferably the method includes the additional step of providing a channel 42 across the surface of the first end 5. In one preferred form, this is achieved by drilling spaced holes along a length of bar and cutting the bar through one of said holes to form the first end with a u- shaped half cylinder channel extending across same as shown.

[00110] It will be appreciated that connectors 40 must be slid on to the reinforcement elements during manufacture of the pre-fabricated reinforcement structure or cage.

[00111] For example, a typical cage structure 43 for a wall type construction, will include two parallel sheets 44 of reinforcement elements welded together into a two-dimensional orthogonal grid as shown in Figure 12. These are each comprised of multiple parallel vertical elements 45 and horizontal reinforcement elements 46, with the two sheets spaced from each other and often retained by further tie elements (see example marked in broken line 47) that extend transversely between the two sheets. In other cage structures the tie elements may be in the form of ligatures 48 that bound the sheets and which are integrally formed with the horizontal reinforcement elements 46 to extend across and between the spaced sheets 44. [00112] A method of constructing a pre-fabricated reinforced concrete form using the connector 40 of the fifth aspect of the invention includes the steps of constructing a reinforcement element structure wherein connectors 40 are slid into selected positions on the cage to extend outwardly therefrom during construction, and releasably securing at least one formwork panel to the first end of the connectors by means of a fastener applied through the formwork panel to each connector. The connectors 40 could be connected to the horizonal elements 46 as shown in positions marked “X” on Figure 12, and/or to the vertical elements 45 as shown in positions marked “O”.

[00113] This form can then be used in a method of a method of constructing a pre-fabricated reinforced concrete structure by: installing the form on site and completing same; pouring concrete into the form and allowing the concrete to solidify; and removing the formwork panel or panels by releasing the panel or panels from the first end of each connector by removing the associated fastener.

[00114] Turning to Figure 14 there is shown one embodiment of a dual function connector 50 that also acts as a cage tie element as described above. In this embodiment, the connector does not terminate at the reinforcement rod receiving through apertures 41 but instead has two opposing first ends 5 and two spaced through apertures 41 between the two first ends for securing to spaced reinforcement elements 3, the length of bar extending between the through apertures serving as tie elements between the spaced reinforcement elements.

[00115] It will be appreciated that while many reinforcement structures are similar to that shown in Figure 14 with two parallel spaced sets of reinforcing elements necessitating two spaced apertures 41 , there may be other variations where only one aperture or more than two apertures may be required. Similarly, it will be appreciated that by constructing the connectors 40 and 50 from plain bar material, the costs and limitations of moulding are avoided, and the connectors can be easily cut to suit an application during construction of the form. For example, the connectors can be made to provide a non-standard offset to achieve, for example, a particular exact concrete cover for a particular application, something that is not easily done with moulded components.

[00116] The connectors 50 of the fifth aspect would typically be applied to a reinforcement structure at say 200mm centres in one direction and about 250 - 300mm spacing in a transverse direction. Suitable fasteners are considered to include a type 17 timber screw with an overall embedment length of at least 25mm, although it is envisaged that other fasteners specifically designed for plastics may also be suitable or preferable.

[00117] With reference to Figures 15 to 17 there is provided a two-part connector 51 in accordance with a further embodiment of the invention. Where convenient, like reference numerals have been used to denote corresponding features.

[00118] The two-part connector 51 includes a first part 52 and a second part 53. By having the connector in two parts, it should be noted that attachment of the form panel 2 to the reinforcement rod 3 is independent of the manufacture of reinforcement cage 43. This can now be done off site or at a construction site.

[00119] As best shown in Figure 17, the first part 52 of the connector 51 is based on the connector 1 of the first aspect for placement around the reinforcing rod 3. As such, the first part 52 includes a reinforcing rod retention means in the form of an openable contoured region 18 that has inwardly directed stop formations shown at 19. The first part further includes dovetailed tabs 54 for complementary sliding engagement with corresponding dovetailed apertures 56 in the second part 53. The second part 53 includes a first connection means in the form of a panel abutment surface to bear against an adjacent form panel and a fastener receiving region adapted to retainingly receive a releasable fastener applied through an opening in an adjacent form panel placed against the abutment surface.

[00120] It is proposed that during installation, the first part 52 is first engaged with the reinforcing rod 3. The second part 53 of the connector 51 is then slid over the first part 52 such that the dovetailed tabs 54 slidingly engage with the dovetailed apertures 56. Once this occurs, a slight interference fit is created over reinforcing rod 3 to ensure the assembled connector 51 does not slip or rotate.

[00121] Once the two parts are engaged with each other, the form panel 2 can then be attached to the connector 51 in the similar method as described in the fifth aspect in Figure 13. Under these circumstances, the form panel 2 is aligned such that the panel abuts to bear against the second part 53. Securing of the panels to the second part 53 is by way of suitable fasteners such as tek type screws or similar screws which are designed specifically to screw into and engage with the PVC material of the second part 53. In one proposed form, the tek type screw is a 35mm long Type 17 Flex head Masbolt™, part number 17HC1235. [00122] In one possible method, once the form panel 2 is in the correct position, a pilot hole is first drilled into the second part, via the hole in the form panel. The tek screw is then screwed through the hole in the form panel and into the pilot hole creating a female thread thereby securing the form panel to the second part 53. As with the earlier embodiments, once all the formwork has been erected and the concrete has been poured and has cured sufficiently to hold its form, the fasteners can be unscrewed while the concrete is still green and the form panels 2 can be removed. In this manner, the concrete can be readily inspected and the form panels can be re-used multiple times, depending on the material. The only finishing required will be to patch the small holes around the fastener receiving regions of the connectors.

[00123] It should be appreciated that the tabs 54 are dovetailed to prevent the second part 53 from spreading when load is applied. The use dovetailed tabs also reduces the cross section of the first part 52 thus decreasing the cycle time for plastic injection. The first part 52 is preferably manufactured from ‘nylon 6’ or similar high strength ductile plastic. The second part 53 is preferably extruded from PVC. Using an extrusion process allows the part to be then cut into pieces of differing length to suit the load required. Chamfers 55 are also provided as part of the second part 53 to assist the extrusion process and help minimise the area of connector showing at the formed concrete surface.

[00124] Advantageously, using the two-part connector 51 of the present embodiment allows the form panels 2 to be installed independent of the construction of the reinforcement cage. In this way, the reinforcement cage may be prefabricated as in the earlier aspects and embodiments. Installation is therefore much more flexible and less onerous because the connectors 51 can be positioned where required. The two-part connectors 51 of the present embodiment can be positioned on the reinforcement rods 3 before the holes in the form panels are drilled, or after to align with pre-drilled holes. No additional metal inserts are required as the screws 13 are simply screwed into the PVC material of the second part 53 simplifying manufacture, distribution and tracking.

[00125] It will also be appreciated that while one particular arrangement has been disclosed in relation to the embodiment described in Figures 15 to 17, other dovetail tab configurations could also be used.

[00126] It should be appreciated that in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, Figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this invention.

[00127] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

[00128] While there has been described what are believed to be the preferred embodiments of the invention, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as falling within the scope of the invention. For example, any formulas given above are merely representative of procedures that may be used. Functionality may be added or deleted from the block diagrams and operations may be interchanged among functional blocks. Steps may be added or deleted to methods described within the scope of the present invention.