Background of the Invention Typically expansion or keyed jointing systems are used to combat problems associated with cracking of concrete due to thermal expansion and contraction.

A typical type of concrete keyed joint is disclosed in Australian patent 604612. This discloses a keyed joint plate assembly which includes a joint plate which is roll formed from sheet metal.

The joint plate consists of upper and lower vertical sections and a central channel section formed by an upper and lower inclined section which converge to a vertical centre section 15 parallel to the top and bottom sections. The inclined upper and lower sections are provided with a pair of aligned holes along the length of their joint plate.

In use a stake formed from sheet metal is received within respective pairs of vertically aligned holes. A wedge is then inserted between each stake and the adjacent wall of the joint plate to ensure that the stake can not easily be moved with respect to the joint plate.

The joint plate assembly described above suffers from a number of deficiencies. As with all types of joint plates it is formed from sheet metal. Once a stake is wedged in position it is difficult to adjust this position with any degree of accuracy. This is because the wedge must be hammered out of position and then hammered back into position when the stake has been realigned. The joint plate assembly because it is made of metal has the problem of being conductive and susceptible to rusting. If it is bent out of shape it is difficult to bend it back to the same shape.

The present invention provides an alternative joint plate and joint plate assembly.

Summary of the Invention

According to one aspect of the present invention a keyed joint plate assembly is provided for concrete including a joint plate having substantially co-planar vertical top and bottom sections and an interconnecting central section comprising a rearwardly directed channel including upper and low wall sections, with vertically aligned pairs of holes located therethrough and a rearward section, a plurality of elongate members each elongate member being adapted to be received through a respective pair of holes and a plurality of fixing means, each fixing means adapted to be connected to each elongate member to fix the position of each elongate member with respect to the joint plate.

It is preferred that the joint plate comprises a plurality of openings therethrough, each opening being in a position adjacent the position where an elongate member is to be received, whereby one or more fixing means can be inserted therethrough.

It is preferred that each opening is aligned co- planar with a respective pair of the holes.

Each opening may be located in the rearward section.

Alternatively each opening is located in the upper and/or lower wall sections.

Each opening may comprise a horizontal slot.

The upper wall section may be inclined downwardly.

It is preferred that the lower wall section is substantially horizontal.

According to an alternative embodiment the lower wall section is inclined upwardly.

The rearward wall section may be vertical.

Alternatively the rearward wall section may be curved.

It is preferred that the joint plate comprises a lateral flange section extending along the length of the joint plate.

The joint plate preferably comprises a plurality of flange sections extending along the length of the joint plate.

Each lateral flange section may comprise a lateral extension on at least one side of the joint plate.

It is preferred that the lateral flange section comprises a lateral extension on the upper and lower wall sections or top and/or bottom sections.

It is preferred that each lateral flange serves to prevent access of water and ants.

It is preferred that each elongate member comprises a threaded rod.

Each fixing means may comprise a clasping member.

Each clasping member may comprise finger sections which are arranged to clasp an elongate member.

Preferably each clasping member is adapted to be inserted through a respective opening so that the finger sections are located on the inner side of the joint plate and a body section is located on the opposite side of the joint plate.

The clasping member may comprise a clip with finger sections resiliently moveable apart to allow one elongate member to be clasped and retained in a recess defined between the finger sections and the body section.

The clasping member may be C or U-shaped.

It is preferred that the finger sections converge.

It is envisaged that the clasping member may comprise a section which can be fixed to one elongate member and another section which can be fixed to the joint plate.

According to another embodiment the clasping member does not need to be inserted through a hole in the joint plate but instead comprises upper and lower clasping sections to clasp an elongate member above and below the pair of holes.

It is preferred that the assembly comprises connectors which allow joint plates to be connected end to end.

It is preferred that the end connectors are H- shaped.

According to another aspect of the present invention

a joint plate is provided for concrete and formed from plastic, the joint plate comprising a substantially co- planar vertical top and bottom section and an interconnecting central section having a rearwardly directed channel including upper and lower wall sections, with vertically aligned pairs of holes located therethrough and a rearward section.

Preferably the rearward section includes an opening therethrough which is adapted to receive a clip for fixing a threaded rod inserted through the pair of holes.

According to another aspect of the present invention there is provided a joint plate for concrete comprising an upright wall and a side wall which extends therefrom and terminates at a position removed from the plane of the upright wall.

It is preferred that the side wall has a hole therethrough and is adapted to receive an elongate member which is to be fixed in position by a fixing means.

Preferably the side wall is located at a lower end of the upright section.

The side wall may be substantially horizontal.

The joint plate may comprise a base wall including the side wall on one side of the upright section and another side wall on the opposite side of the upright section.

The upright section may include an upper substantially vertical wall.

The base wall may be substantially horizontal.

It is preferred that the joint plate is T-shaped when inverted.

It is preferred that the other side wall decreases in thickness as it extends away from the upright wall.

The hole in the side wall is preferably located at an outer end of the side wall.

It is preferred that a fixing means is provided which is connectable to the elongate member on either side of the side wall.

It is preferred that the elongate member is a

threaded rod.

According to another embodiment the fixing means comprises an elongate member holding section and a joint plate holding section which enables the position of the elongate member to be fixed with respect to the joint plate.

Brief Description of the Drawings A preferred embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 shows a perspective view of a keyed joint assembly according to a first embodiment of the present invention; Figure 2 shows a cross-sectional side view of the assembly shown in Figure 1; Figure 3 shows a top view of a plastic compression clip of the present invention when connected to a steel rod; Figure 4 shows a perspective view of the compression clip shown in Figure 3 connected to a steel rod with an external thread; Figure 5 shows a perspective view of a connector according to the present invention for connecting joint plates end to end; Figure 6a shows a side view of a joint plate according to a second embodiment of the present invention; Figure 6b shows a side view of a joint plate according to a third embodiment of the present invention; Figure 6c shows a side view of a joint plate according to a fourth embodiment of the present invention; Figure 7a shows a side view of a joint plate according to a fifth embodiment of the invention with a clip according to a second embodiment of the invention; Figure 7b shows a side view of a joint plate according to a sixth embodiment of the present invention with a clip according to a third embodiment of the

invention; Figure 7c shows a side view of a joint plate shown in Figure 7a with a clip shown in Figure 3; Figure 8 shows a side view of a joint plate according to a second aspect of the present invention; and Figure 9 shows a clip according to a fourth embodiment of the present invention.

Description of the Preferred Embodiment The keyed joint plate assembly shown in Figure 1 consists of a keyed joint plate 10 having upper and lower vertical sections 11, 12 with a centrally located channel 13 having an upper wall 14 inclined downwardly and a lower wall 15 which extends horizontally to a vertical wall 16 which interconnects the walls 14 and 15.

The upper wall 14 and lower wall 15 are provided with holes 17, 18 which are aligned vertically close to the vertical wall 16. Aligned in the same plane with these holes 17 and 18 is a horizontal slot 19 located in the centre of the vertical wall 16.

A number of hole pairs 17, 18 and slots 20 are provided along the length of the channel section 13.

The assembly is completed by inserting a threaded steel rod 21 through the holes 17, 18. A clip 22 is then inserted through slot 20 so as to clip onto the rod 21.

As shown in Figure 3 the clip 22 consists of a C-shaped member having resilient fingers 23, 24 pointing in the same direction and defining a central opening 25 which is adapted to receive the threaded rod through the gap between the fingers 23, 24.

The fingers are movable apart so that the threaded rod 21 can fit between them.

It is preferred that the clip is made of plastic and that the joint plate is made from a plastic such as PVC.

As shown in Figure 4 the exterior thread 26 of the rod 21 enables a stronger connection between the clip 22 and the rod 21.

The joint plate 11 is also provided with lateral

fins 27 which extend on either side of the upper and lower vertical sections 11, 12. These fins 27 decrease in width away from the upper and lower sections 11, 12 and in the embodiment shown the fins 27 on the right hand side are slightly lower with respect to the fins 27 on the left hand side of the sections 11, 12.

To enable adjacent sections of joint plate 10 to be connected end to end, a plastic H-shaped connector 28 can be used. With the ends of two joint plates 10 fitting into the respective recesses formed between the legs of the H-shaped clip.

Figure 6a shows an alternative shaped joint plate having a Z-shaped central section in lieu of the channel section 13 of the first embodiment shown in Figure 1. As shown in Figure 6a the Z-shaped central section consists of horizontal upper and lower walls 30, 31 and a diagonal wall 32.

Figure 6b shows an arcuate shaped channel section 30 in lieu of the channel section 13. In this embodiment the arcuate shaped channel section 33 is semicircular.

In Figure 6c two channel sections 34, 35 are provided, one above the other and separated by a vertical wall 36. The upper and lower walls 37, 38 of each channel section 34, 35 converge slightly towards the vertical rearward section 39.

In Figure 7a the joint plate 43 shown in Figure 1 is slightly altered to remove the horizontal slot 20. This is because the clip 22 is replaced by a different type of clip 40 which has a vertical section 41 which extends adjacent the vertical section 42 of the channel section 43.

The vertical section 41 of the clip 40 interconnects upper and lower clip sections 44, 45 each having the shape of the clip shown in Figure 3. These upper and lower sections 44, 45 are located respectively above and below the holes 46, 47 in the upper and lower walls of the channel section 43 so as to clasp a rod 48 inserted therethrough.

In Figure 7b the joint plate of Figure 1 is further modified to provide two horizontal slots 50, 51 in the vertical section 52 of the channel 53 and a clip similar to that shown in Figure 7a is used except it is shortened in length so as to fit through the slots 50, 51 so as to clasp a rod located through holes 54, 55 in a manner as previously described. The upper and lower sections 56, 57 of the clip are arranged horizontally and in parallel.

In figure 7c a single clip as shown in Figure 1 is used and the slot 20 shown in Figure 1 is removed. This clip 60 is located below the horizontal section 61 of the channel 62. This prevents movement of the joint plate 63 downwardly with respect to the rod 64 which is inserted through it.

Another aspect of the present invention is shown in Figure 8. This aspect includes a joint plate which has a vertical wall 70 on a horizontal base wall 71. On the left hand side of the upright 70 the base wall 71 is of constant diameter and is provided with a vertical hole 72 to allow a threaded rod 73 to be inserted therethrough.

The clip 74 is similar to clip 50 shown in Figure 7b but has a much shorter vertical section which is used to fix the rod 73 with respect to the base wall 71.

As shown in Figure 9 the clip 74 is shown with two parallel planar sections 75, 76 with a slot 77 defined therebetween. Each planar section 75, 76 has a similar shape to the clip shown in Figure 3. It is preferred that the slot 77 has the same width or a slightly larger width than that of the base-wall 71.

On the right hand side of the upright 70 the base wall 71 tapers to its end 78. This right hand section serves as a barrier to water or ants passing above or below the base wall 71.

Below the base wall 71 directly in line with the vertical wall 70 a lower extension 90 can be provided as a means to induce a fracture in concrete therebelow when the joint plate assembly is in use.

It is preferred that the vertical height of the

joint plate is 35mm and the base wall length is 42mm.

In use one of the joint plates can be used and fixed to a threaded rod using one of the clips described previously. If it is necessary to adjust the position of the rod with respect to the joint plate this can be done by simply removing the clip and reconnecting it at the new position. Joint plates can be aligned end to end using the connector shown in Figure 5 or any similar connector which achieves the same objective.

By using plastic instead of metal for the joint plate advantages can be obtained over existing metal joint plates. These include low friction, no rusting, greater resilience and electrical insulative properties.

In addition the plastic material is much easier to work with a hacksaw for example than metal joint plates and it is much easier to handle.

In addition the particular assemblies described above allow easier adjustment of rods with respect to joint plates and the threaded rods in conjunction with the clips provide a stronger connection between the rods and the joint plates.

According to another related aspect of the present invention a keyed joint plate assembly is disclosed which in its preferred form is made of plastic. Plastic inherently is susceptible to expansion and contraction in extreme weather conditions. For example a joint plate made of plastic when left outside in direct sunlight is liable to expand longitudinally as well as laterally. If this occurs when the joint plate is located in a concrete forming structure this will cause the joint plate to warp along its length thus having an adverse effect on the ability of a concrete forming structure to perform its desired function.

The warping occurs primarily because the ends of the joint plates are normally fixed end to end to form a length of joint plate. When expansion of the joint plate occurs this naturally leads to buckling or warping of the joint plate.

According to the present invention a device is provided for connecting joint plates together which allows for expansion of joint plates connected end to end.

The present invention provides a device for connecting joint plates together comprising substantially coplanar vertical top and bottom sections and an interconnecting central section comprising a rearwardly directed channel including upper, lower and rearward wall sections, wherein at least a part of each end wall of the device comprises a coupling means for coupling a joint plate to each end wall.

It is preferred that each coupling portion is located on one or both of the vertical top and bottom sections.

Preferably each coupling portion is located on the central section.

Each coupling portion may comprise a guide.

Each guide may comprise substantially parallel surfaces separated by a gap which is adapted to receive part of a joint plate.

It is preferred that the coupling portion comprises a pair of parallel walls, one being at least part of the vertical top wall.

The coupling portion may comprise a pair of parallel walls, one being the vertical bottom wall.

The coupling portion may comprise two pairs of parallel walls, one pair forming the vertical top section and another pair forming the vertical bottom section.

It is preferred that the vertical top section comprises a pair of parallel walls separated by an interconnecting wall.

The vertical bottom section may comprise a pair of parallel walls separated by an interconnecting wall.

The interconnecting wall may be substantially perpendicular to both parallel walls.

The device may comprise a locating means for aligning a joint plate with the coupling portion.

The locating means may comprise a slot located in end walls of the device.

It is preferred that a plurality of slots are provided in the top and bottom sections.

Slots preferably extend at least part way between end walls of the device.

According to one embodiment a specially configured slot is located in each end wall the slot being configured to receive a matching male portion of a joint plate.

According to another embodiment the device comprises at least one male coupling portion adapted to receive a matchingly configured female portion of a joint plate.

A preferred embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 10 shows a perspective view of a device for connecting joint plates together.

As shown in Figure 10 a connector device 110 in accordance with the present invention comprises an upper vertical section 111, a lower vertical section 112 and a mid section 113 in the form of a channel interconnecting sections 111 and 112.

The channel 113 comprises upper and lower walls 114, 115 which converge slightly towards a vertical rearwardly disposed wall 116. The overall configuration is similar in shape to the joint plate shown in Figure 1 of the previously referenced provisional patent application.

The shape of the connector device may vary in accordance with the shape of the joint plates with which it is to be used.

The upper section 111 comprises a pair of substantially parallel vertical walls 117, 118 which are separated by centrally located vertical section 119. The lower section 112 is formed from similarly configured parallel vertical walls 120, 121 with a separating section 122.

A slot is located approximately midway between each

pair of vertical walls 117, 118, 120, 121 and extends between the end walls 124, 125, 126, 127.

In use the connector 110 is adapted to receive a joint plate between the parallel walls 117, 118, 120, 121 at each end of the device 110.

Because each joint plate is designed with ant and waterstop fins, slots 123a, 123b are provided to allow the fins to be received therein when the ends of the joint plates are located between the parallel walls 117, 118, 120, 122.

With the upper and lower vertical sections of a joint plate received between the parallel walls 117, 118, 120, 122 at each end of the device 110 so that they approach the front face of vertical sections 119, 122, a continuous joint plate assembly can be formed which is effectively co-linearly aligned. If expansion of the joint plates occurs each end of the joint plate will be able to expand within the gaps formed by vertical walls 117, 118, 120, 121 so that there is no deformation of the joint plates. In this respect it is noted that the joint plates will not abut completely with the vertical walls 119, 122 so that there is room for expansion.

According to another variation of the present invention the connector device is formed into a right angled section with the pairs of parallel walls located at each end of the elbow section so as to allow joint plates to be connected together so as to form a continuous right angle section.

In accordance with another embodiment of the present invention a compression clip 130 is adapted to be received in the gaps formed between the pairs of parallel vertical walls 117, 118 and/or 122 or 121. The compression clip 130 is formed with a gap between two leg portions 131 so as to be received in either side of the vertical section 119. The compression clip 130 can be used as a spacer and can then be removed after all support pegs have been put in place and clipped.