The present invention relates to a permanent formwork system for reinforcing concrete structures and in particular to a system utilising lightweight hollow panels which are pre-manufactured, erected on site and filled with concrete to form the structure. The lightweight hollow panels may also be insulated panels having a sheet of insulation on one or both faces.

The panels are generally formed from sheets of fibre cement board which themselves form the outer wall surfaces of the actual formwork structure. The sheets of fibre cement board are kept apart in a mutually parallel arrangement by a plurality of connectors which are evenly distributed in the space between the sheets to allow for an even distribution and flow of concrete. The connectors and any strengthening bars supported by the connectors are incorporated into the final structure.

Typical prior art connectors come in many forms and can be made from metal, timber or plastics material. All have to be of identical size so that the boards are kept spaced apart in a mutually parallel arrangement.

The disadvantage associated with prior art connectors in particular is that different sized connectors are required for walls of different thickness and it is necessary to carry a large inventory of different sized connectors.

The object of the invention is to alleviate the above disadvantage.

The present invention provides a wall connector for locating between two parallel sheets of fibre cement formwork boards, for maintaining the sheets in a parallel arrangement with other like wall connectors, each wall connector comprising an oblong shaped body having two pairs of mutually opposed side walls and a pair of open ends, with the first pair of mutually opposed side walls being spaced apart from one another by a first distance and the second pair of mutually opposed side walls being spaced apart from one another by a second distance which is greater than or less than the first distance but not equal to the first distance, each of the respective pairs of side walls being securable to the sheets so as to maintain the sheets apart by either the first or second distance, and the ends of the oblong body being substantially open to allow for the flow of concrete, cement or other setting material.

Advantageously, the edges of each of the four side walls of the connectors are provided with at least one open ended opening for receiving at least one vertical reinforcing bar for a structure, with the openings in each wall connector being arranged in a staggered layout when secured to a sheet, so that the vertical reinforcing bar can extend through alternate openings in a column of wall connectors, and with an inner wall being provided within the body and one or more openings being provided in the inner wall to accommodate at least one horizontal reinforcing bar, or alternatively the connectors are arranged in a non-staggered layout in which the horizontal reinforcing bar rests on the U channels in a row of wall connectors and the vertical reinforcing bar extends through the openings in the inner walls of the connectors.

The open ended openings may comprise U-shaped channels.

Conveniently, the wall connectors are manufactured from a material such as a high impact polystyrene (HIPS).

Preferably, the wall connector is a three dimensional oblong construction having a length "X", a width "Y" and a height "Z" having two side walls each of which is securable to the formwork sheets separated by an upper wall and a lower wall so that the sheets are maintained apart by the distance "Y". Ideally, the wall connector may be orientated through 90 ^° , so that the upper walls are securable to the formwork sheets with the distance "Z" of the side walls being the spaced apart distance between the sheets the distance "Y" and the distance "Z" determining the reinforced concrete wall thickness.

Conveniently located in the central region of the wall connector, is an inner wall which gives structural rigidity to the wall connector which is further strengthened by a plurality of ribs extending from both sides of the inner wall in between a plurality of air holes in the inner wall, at the centre of the inner wall being a central orifice having a plurality of rounded comers, and the side walls, the top wall and the bottom wall have U-shaped channels or receivers. Advantageously located in the side walls and the upper and lower walls are a plurality of triangular shaped air holes which facilitate the flow of concrete when poured into the formwork, the holes also assisting in the adhesion of the walls to the sheets of fibre cement board.

The present invention also provides a method of assembling a formwork structure from two parallel sheets of fibre cement formwork boards and a plurality of wall connectors as herein defined comprising laying a first sheet on an assembly jig, marking the location of the connectors on the first sheet using a marking means to provide a staggered arrangement for the connectors; applying a deposit of bonding means to each location; placing a side wall of a connector on each deposit of bonding means; applying further bonding means to the opposite side wall of each connector; and then laying a second sheet on the connectors so that the second sheet is bonded to the connectors to complete an assembled formwork panel. A further aspect of the invention provides an apparatus for assembling a formwork structure comprising panel assembly jig utilised for assembling a stack of completed rectangular formwork panels, irregular shaped formwork panels and small sized panels, the panel assembly jig comprising a box section frame, which is open at one side, and includes an elongate side section and two end sections located about two adjustable platforms between which is locatable a pallet, extending upright from the elongate side sections are two locating upright arms mounted on sleeves having lateral side arms, mounted on each lateral side are is a movable and pivotable sleeve from which extends an upright locating arm which can be positioned to keep the formwork panels in position and parallel to one another or moved away to allow access to a stack of assembled panels, the panels being assembled one on top of another until the uppermost panel reaches the top of the locating arms.

Ideally, the arms are adjustable to accommodate an angled wall panel and a smaller wall panel, thus enabling the panel assembly jig to be used to align and secure stacks of the angled wall panels and the smaller wall panels.

Conveniently, the formation of corner units is achieved utilising a corner assembly jig in which the comer unit comprises a right angled strip of metal or any other suitable material to which is attached two elongate sheets of fibre cement board of the desired width which are screwed into position on the strip along the corner support of the jig, the cut outs along the support allowing clearance for the screws, the location of the cut outs being also marked on the lower edge of the support and the movable supports are adjustable to allow for the different widths of the sheets.

Advantageously, an end-trim jig is utilised in the formation of end-trim panel to close off each section of an exposed wall panel using an end-trim panel which comprises two right angle members to which is attached an elongate sheet of fibre cement board, the right angle members are located in position on the end support which has an end stop which is adjustable in the different dimensional slots, it also being possible to locate the end stop in one of the slots so that the elongate sheet of fibre cement board overhangs the right angle members by an amount equal to the thickness of the board so as to close off the edges of the completed wall panel exactly.

The invention will hereinafter be described with reference to the accompanying drawings which show, by way of example only, two embodiments of a wall connector used in a formwork system according to the invention and also three jigs for use in assembling the formwork system. In the drawings: Figure 1 is a perspective view from one side and from above of a first embodiment of wall connector for use in assembling a wall connector according to the invention; Figure 2 is a perspective view from one end of the first embodiment of wall connector as shown in Figure 1 ;

Figure 3 is an end view of the wall connector located between two sheets of material or boards, with the shorter sides of the connector being used to space apart the sheets or boards;

Figure 4 is an end view of the wall connector similar to Figure 3 but with the longer sides being used to space apart the sheets or boards; Figure 5 is a perspective view of an assembled wall structure with the front wall removed and showing a plurality of wall connectors secured to the rear wall and retaining a series of horizontal and vertical reinforcing bars for the reinforcement of concrete which will be poured into the structure;

Figure 6 is a plan view of the assembled formwork wall structure showing a number of wall connectors, a horizontal reinforcing bar and two vertical reinforcing bars;

Figure 7 is an end elevation showing end views of two wall connectors, a vertical reinforcing bar and two horizontal reinforcing bars; Figure 8 is a perspective view from one side end from above of a second embodiment of wall connector for use in assembling a wall connector according to the invention;

Figure 9 is a perspective view from one end of the second embodiment of wall connector as shown in Figure 8;

Figure 10 is an end view of the wall connector located between the two sheets of material or boards, with the shorter sides of the connector being used to space apart the sheets or boards;

Figure 1 1 is an end view of the wall connector similar to Figure 10 but with the longer sides being used to space apart the sheets or boards;

Figures 12 to 15 are a series of four perspective views of a panel assembly jig for assembling and stacking assembled formwork wall panels in accordance with the invention, illustrating the sequential assembling and stacking of wall panels as shown in Figure 15;

Figures 16 and 17 are perspective views of the panel assembly jig rearranged for the assembly and stacking of different shaped and different sized wall panels respectively; Figure 18 is a perspective view of a corner assembly jig used to form corner connections for fixing to two wall panels which end at a corner;

Figure 19 is an exploded perspective view of the key elements of the corner assembly jig;

Figure 20 is a further exploded perspective view of a comer connection and its components being assembled on the corner assembly jig;

Figure 21 is an end view of the corner assembly jig showing an alternative setting for a different sized comer connection ;

Figure 22 is a perspective view of the end-trim jig used to form end-trim panels to close off the end section of an exposed wall panel; Figure 23 is an exploded perspective view of an end-trim panel and its components being assembled on the end-trim jig;

Figure 24 is a perspective end view of the upper components of the end-trim jig; and Figure 25 is an exploded perspective view of the end-trim jig as shown in Figure 24.

Referring to the drawings and initially to Figures 1 to 7, the first embodiment of a wall connector 100 according to the invention is used for spacing apart, with a plurality of other similar wall connectors, two sheets of fibre cement boards 101 and 102 (see Figures 3 and 4) to maintain both sheets apart an equal and uniform distance prior to the pouring of a wet concrete material between the sheets 101 , 102 which act as a permanent formwork for the wall structure.

The wall connector 100 is a three dimensional oblong construction having a length "X", a width "Y" and a height "Z". It has two side walls 104, 106 each of which is securable to the formwork sheets 101 , 102 separated by an upper wall 108, and a lower wall 1 10 as shown in Figure 3 so that the sheets are maintained apart by the distance "Y". However, as shown in Figure 4, the wall connector may be orientated through 90 ^° , so that the upper walls 108 and 1 10 are securable to the formwork sheets 101 , 102 with the distance "Z" of the side walls 104, 106 being the spaced apart distance between the sheets 101 , 102. In a non-limiting example, the distance "Y" is 75mm and the distance "Z" is 100mm. This distance determines the reinforced concrete wall thickness.

Located in the central region of the wall connector 100 as shown in Figure 3, is an inner wall 1 15 which gives structural rigidity to the wall connector 100 which is further strengthened by eight ribs 1 17 extending from both sides of the inner wall 115 in between a series of air holes 1 16. At the centre of the inner wall 1 15 is a central orifice 118 having four rounded corners 120. Formed at each end of the wall connector 1 00 in the side walls 104, 106, the top wall 108 and the bottom wall 1 10 are four U- shaped channels or receivers 124.

With reference to Figure 2, located in the side walls 104, 106, upper and lower walls 108, 1 10 are a series of triangular shaped air holes 126 which facilitate the flow of concrete when poured into the formwork. These holes 126 also can assist in the adhesion of the walls 104, 106 or 108 to 1 10 to the sheets 101 , 102 of fibre cement board.

The use of the connectors 100 will now be explained in relation to Figures 5 to 7. The connectors 100 are mounted in regular and alternately staggered rows 130 and 131. In practice a first sheet of fibre cement board is laid out flat on a working surface of jig 300 and the connectors 100 are bonded to the sheet by a strong bonding agent or glue following a template marked up on the first sheet. Each side wall 106 of the connectors is pressed firmly against the deposit of glue at each particular location according to the staggered layout. After all the connectors 100 are located in situ, a deposit of the bonding agent or glue is provided on the side wall 104 of each connector 100.

The second sheet of fibre cement board is then laid down on the plurality of connectors 100 and firmly sandwiched together to form a completed wall panel on the jig 300. The next panel is then assembled on the jig 300 by laying another first sheet on the assembled panel, applying the glue according to the template, laying down the connectors, applying glue to the connectors and laying a second sheet on top of the connectors. When the panels are erected on site to be used as structural formwork, reinforcing bars are inserted into the wall panels as shown in Figures 5 to 7 according to an engineer's specification for the particular structure. Horizontal reinforcing bars 140 are threaded through the central orifice 1 18 of each connector 100, so that the reinforcing bars 140 rest on the lowermost corners 120. Vertical reinforcing bars 150 are then threaded through each alternate forward and rearward facing U-shaped channels 124 on each of the staggered rows 130 and 131 .

The amount of stagger between the rows 130 and 131 of the connectors 100 can be varied so as to vary the size of the included hole formed by the offset U-shaped channels 124 on each alternate row. This can make it easier to thread a reinforcing bar through the U-shaped channels 124. A tighter included hole may be more useful on a short panel so that the reinforcing bar is not located at an angle. In an alternative arrangement not shown in the drawings, the connectors 100 are turned through 90 ^° and are aligned without any stagger, thereby providing a large vertical channel between the connectors allowing for the insertion of additional elements such as multiple conduits for services. In this way the horizontal reinforcing bars are seated in the U-shaped channels 124 and the vertical reinforcing bars extend through the central orifices 1 18.

Referring now to Figures 8 to 1 1 , the second embodiment of a wall connector 200 according to the invention is used for spacing apart, with a plurality of other similar wall connectors, two sheets of fibre cement boards 201 and 202 (see Figures 10 and 1 1 ) to maintain both sheets apart an equal and uniform distance prior to the pouring of a wet concrete material between the sheets 201 , 202 which act as a permanent formwork for the wall structure.

The wall connector 200 is a three dimensional oblong construction having a length "X-X", a width "Y-Y" and a height "Z-Z". It has two side walls 204, 206 each of which is securable to the formwork sheets 201 , 202 separated by an upper wall 208, and a lower wall 210 as shown in Figure 10 so that the sheets are maintained apart by the distance "Y-Y". However, as shown in Figure 11 , the wall connector may be orientated through 90 ^° , so that the upper walls 108 and 210 are securable to the formwork sheets 201 , 202 with the distance "Z-Z" of the side walls 204, 206 being the spaced apart distance between the sheets 101 , 102. In a non-limiting example, the distance "Y-Y" is 125mm and the distance "Z-Z" is 150mm. In a non-limiting example, if the sheets are 6mm thick, then the total thickness of the finished wall will be 137mm or 162mm. In a further non-limiting example, if the sheets are 9mm thick, the first wall thickness will be 143mm or 168mm.

Located in the central region of the wall connector 200 is an inner wall 215 which gives structural rigidity to the wall connector 200. Ribs (not shown) may also be provided to give extra structural rigidity to the connector 200. At the centre of the inner wall 215 are two central orifices 218 having four rounded corners 220 as well as a number of air holes 216. Formed at each end of the wall connector 200 in the side walls 204, 206, the top wall 208 and the bottom wall 210 are eight U-shaped channels or receivers 224.

Located in the side walls 204, 206, upper and lower walls 208, 210 are a series of triangular shaped air holes 226 which facilitate the flow of concrete when poured into the formwork.

The connectors 200 are used in a similar fashion as the connectors 100 except that the horizontal reinforcing bars may be inserted through one or both of the central orifices 218 and the vertical reinforcing bars may be inserted through one or both of the central orifices. In an alternative embodiment, the connectors 200 are turned ninety degrees, the amount of stagger between the two rows of the connectors is reduced to zero, thereby providing a large vertical channel between the connectors allowing for the insertion of additional elements such as multiple conduits for services. In this way the horizontal reinforcing bars are seated in the U-shaped channels 224 and the vertical reinforcing bars extend through the central orifices 218.

Referring now to Figures 12 to 17, panel assembly jig 300 is utilised for assembling a stack of completed rectangular formwork panels 310, irregular shaped formwork panels 320 and small sized panels 330. panel assembly jig 300 comprises a box section frame 340, which is open at one side 341 , and includes an elongate side section 342 and two end sections 343 located about two adjustable platforms 345 between which is locatable a pallet 346. Extending upright from the elongate side sections 342 are two locating upright arms 350 mounted on sleeves 351 having lateral side arms 352. Mounted on each lateral side are 352 is a movable and pivotable sleeve 354 from which extends an upright locating arm 360 which can be positioned as shown in Figure 12, 14 and 15 to keep the formwork panels in position and parallel to one another or as shown in Figure 13 moved away to allow access to a stack of assembled panels 310. The panels 310 may be assembled one on top of another until the uppermost panel 310 reaches the top of the locating arms 350 and 360. A weight may also be placed on top of the stack to assist in the gluing process. In Figures 16 and 17 the arms 350 and 360 are adjusted to accommodate an angled wall panel 320 and a smaller wall panel 330. This enables the panel assembly jig 300 to be used to align and secure stacks of the angled wall panels 320 and the smaller wall panels 330.

The formation of corner units is achieved utilising the corner assembly jig 400 shown in Figures 18 to 21 . When the two panels 310 meet at a right angle, it is necessary to close off the open corner with a comer unit 450 which is assembled on the corner assembly jig 400. The corner unit comprises a right angled strip of metal or any other suitable material 452 to which is attached two elongate sheets of fibre cement board 454 of the desired width which are screwed into position on the strip 452 along the comer support 420 of the jig. The cut outs 422 along the open of the support 420 allow clearance for the screws. The location of the cut outs 422 are also marked on the lower edge 424 of the support. The movable supports 430 are adjustable to allow for the different widths of the sheets 454 even when two separate different widths are needed as shown in Figure 21 .

End-trim jig 500 is shown in Figures 22 to 25 and is utilised in the formation of end-trim panel to close off each section of an exposed wall panel. When it is desired to close off the end of a wall panel, use is made of an end-trim panel 550 which comprises two right angle members 552 to which is attached an elongate sheet of fibre cement board 554. The right angle members 552 are located in position on the end support 520 which has an end stop 522 which is adjustable in the different dimensional slots 525. It is also possible to locate the end stop 552 in one of the slots 525 so that the elongate sheet of fibre cement board 554 overhangs the right angle members 552 by an amount equal to the thickness of the board 554 so as to close off the edges of the completed wall panel exactly.

It is to be understood that the invention is not limited to the specific details described herein which are given by way of example only and that various modifications and alterations are possible without departing from the scope of the invention as defined in the appended claims.