PLASTICS REINFORCEMENT MESH

This invention relates to reinforcement mesh made from plastics material.

Plastics mesh reinforcement concrete has been disclosed in Australian Patent Specification 62016/96 and describes a mesh in the form of sheets having square holes and in the form of a lattice as shown in the preferred embodiment. The purpose or advantage of use of the plastics mesh is that it can be cut with a jigsaw and would be quicker to install than conventional wire mesh wherein strands of wires are welded to each other. Reference also may be made to US Patent 4,618,385 which refers to the use of plastics mesh for reinforcement of concrete. The mesh is formed from main continuous strands of greater cross section than minor strands of smaller cross section with the minor strands extending through the main strands. However it is evident from the building industry and in particular concrete reinforcement techniques that use of plastics reinforcement mesh although it has been proposed in the prior art discussed above has not been adopted by the building industry which still uses steel in the form of bars or mesh (also known as "re-bar") which has been used as a reinforcement for concrete slabs for many years. However use of re-bar is designed to experience some form of loading, whether that loading would be carrying traffic, spanning a void or bearing another structure such as an upright wall. In many slabs, steel mesh has also been used as a crude and often ineffective method of crack control. Latest developments in concrete technology now includes reinforcement in the form of fibres, notably polymeric fibres as well as steel or glass fibres. Fibre reinforcement is predominantly used for crack control and not structural strengthening.

When reinforcement is required for structural reasons, the slab will more than likely require the use of high tensible steel bars as well as fabric mesh which may be cut to required size on site. Fabric mesh uses wires of varying diameters, i.e. from 6 to 8mm. In applications requiring heavy

reinforcement, there may be utilised two sheets of fabric mesh located top and bottom of the slab.

Usually there will always be a minimum of 50m cover over steel reinforcement from above, below and around the slab. The mesh fabric may be supported from beneath at regular intervals by pad stones, which are often broken pressed concrete flagstones or "bar chairs" which are purpose made plastics or steel supports. Reference may be made to a variety of prior art specifications which describe various forms of bar chairs and in this regard reference may be made to Australian specifications 20013579, 199944587, 735297, 686545, 671734 and US Patent 6,883,289 which all describe various forms of upright supports or structures that generally have one or more notches or recesses for supporting adjacent steel bar(s). However it is important to stress that each of the "bar chairs" as they are known in the building industry are separate from the mesh fabric. In particular reference may be made to US Patent 6,282,860 which describes a bar chair having a body in the form of a ring or disk or a rectangular body having a continuous side wall or frame having a plurality of recesses located in an upper surface of the side wall or side frame to retain a corresponding number of steel bars of a reinforcement mesh. Reference also may be made to US Patent 3,950,911 which describes reinforcing mesh which is self supporting in the sense that intersecting bars of the mesh may each be provided at appropriate locations with angular bent ends which space the mesh above the ground. Thus in this reference the angular bent ends of each steel bar of the steel mesh fabric may replace the conventional bar chairs which are referred to above.

However conventional metal wire fabric mesh has a number of disadvantages which include:

(i) relatively heavy and thus being labour intensive in installation; (ii) capable of causing injury in the sense of having outwardly extending lugs or having sharp ends;

(iii) when using individual bar chairs it was necessary to adjust each bar chair so as to have the same height above the ground or relevant

support surface; and

(iv) capable of corroding due to rust which will cause expansion thereby causing the concrete to crack.

It is therefore an object of the invention to reduce the abovementioned disadvantages of the prior art.

The invention therefore provides reinforcement mesh having intersecting filaments made from plastics material which are provided with a plurality of integral supports which elevate the filaments above the ground or other suitable support surface. Each integral support is suitably located at points of intersection of the filaments although it is stressed that while it is preferred to have all points of intersection of the mesh provided with an associated integral support that this is not essential and that each support may be provided at selected or desired intersection points.

It is also within the scope of the invention to have the integral supports located along spaced intervals of each intersecting filament and this may be in lieu of or in addition to the lugs being located at intersection points. However the location of the supports at intersection points is preferred.

The mesh for use in the invention may have filaments formed from any suitable plastics material which includes high density polyethylene (HDPE), low density polyethylene, polypropylene and copolymers of HDPE and polypropylene, polyesters and polyamide.

The mesh may comprise filaments which have the same diameter or have different diameters as described in US Patent 4,618,385. In any event the filaments may be welded to each other or a smaller diameter filament may extend through a mating aperture in the larger diameter filament as described for example in US Patent 4,618,385.

It will also be appreciated that while it is preferred that each filament may be circular as will be apparent from reference to the term "diameter" above it is also possible that each filament may be square, polygonal, rectangular, triangular or any other suitable cross sectional shape.

The mesh of intersecting filaments may each have a plurality of integral supports wherein each support in one embodiment may comprise a

leg or stem having at a free end therefore an enlarged foot or base. This has regard to a first embodiment of the invention. It will be appreciated that each leg may have any suitable cross section such as round or other suitable cross sectional shape as described above for each intersecting filament. The foot may also have preferably a plate like shape which may be round, square, rectangular or polygonal. Alternatively the foot may be conical, cylindrical or spherical.

In a second embodiment of the invention each support may comprise a frame or body having a plurality of legs or uprights optionally interconnected by webs and also having a foot as described above.

Reference may be made to a third embodiment of the invention wherein there are provided overlapping layers of plastics reinforcing mesh. Such layers may be attached to adjacent layers by any suitable attachment means such as ties or fasteners but preferably such attachment means includes the use of integral clips or sockets which form part of each layer of plastics mesh.

Also in relation to the second embodiment as well as the first embodiment described above use may be made of bar chair assemblies which include a base component which is locatable on the ground or other suitable support surface and one or more upper components attachable or locatable in the base component which ensure that the layer of mesh is located at a desired height above the support surface.

Reference may now be made to a preferred embodiment of the invention as shown in the drawings attached hereto wherein: FIG 1 is a perspective view of reinforcement mesh constructed in accordance with the first embodiment of the invention.

FIG 2 is a perspective view illustrating the bar chair assemblies described above as well as the use of integral clips or sockets described above; FIG 3 is a perspective view of the attachment between the base component and upper component of the bar chair assemblies;

FIG 4 is a perspective view of overlapping layers of mesh;

FIG 5 is a view of alternative profiles of the filaments used in the plastics mesh;

FIGS 6, 7 and 8 refer to one type of overlapping arrangement of mesh within the scope of the invention wherein FIG 6 refers to a base layer and FIGS 7 to 8 refer to the overlapping layers;

FIGS 9, 10 and 11 refer to another type of overlapping arrangement of mesh layers within the scope of the invention wherein FIG 9 refers to a base layer and FIGS 10 to 11 refer to the overlapping layers; and

FIGS 12, 13 and 14 refer to yet another type of overlapping arrangement of mesh layers within the scope of the invention wherein FIG 12 illustrates a base layer and FIGS 13 to 14 refer to the overlapping layers.

The plastics reinforcement mesh 10 shown in FIG 1 includes intersecting filaments 11 and 12 which intersect at intersection points 13. There are also provided a plurality of integral supports or chairs 14 which form a one piece moulding with filaments 11 and 12. It will be appreciated that while supports 14 each having a leg 15 and foot 16 are located at each intersection point 13 this is only a preferred or desirable feature of the invention.

In FIGS 2 to 3 there is shown plastics reinforcement mesh 10A having filaments 17 and 18 which are integral with each other at intersection points

19. There is also shown locator clips 20 integral with filaments 17 and 18 having an integral socket 2OA for supporting an overlapping mesh layer as shown in FIG 4. There is also shown bar chair assemblies 21 which comprise base components 22 having foot or rounded base 23 and a plurality of planar legs, body panels or wings 24. There is also shown attachment spigot 25. On the other hand upper component 26 has a plurality of wings or legs 27 surrounding a central socket 28 which telescopically engages with spigot or projection 25.

However it will be appreciated that the engagement between base component 22 and upper component 26 may involve any type of male- female interaction or snap fit or interference fit wherein a projection or number of projections of either the base or upper component will engage

with corresponding sockets of the other component.

FIG 2 also shows that each bar chair assembly 21 may have varying heights as may be required for supporting mesh 1OA. Thus for example alternative heights of 50mm, 75mm and 100mm may be achieved. The height of 50mm may be achieved with use of upper component 26 only which is this embodiment may be provided with base 23A as shown by support 26A. However base 23A may be dispensed with as also shown in

FIG 2. Support 21 A may refer to the height of 75mm and support 21 B may refer to the height of 100mm. In another embodiment bar chairs 21 of different heights may be used to form concrete slabs having a desired angle to vertical.

FIG 4 shows an arrangement of overlapping mesh panels or layers 10B and 10C attached to each other by locator clips 20.

FIG 5 shows alternative profiles that may be used for each of filaments 17 to 18.

In FIG 6 there is shown a base panel or layer 10D and overlapping panels 10E ₁ 10F and 10G in FIGS 7 and 8 so as to create a four layer overlap as shown in FIG 8 having regard to central region 30 of mesh assembly 31 shown in FIG 7. It is a feature of the four layer overlap that panels 10D, 10E, 10F and 10G have uncut corners shown in FIG 8 by the arrow in full outline.

Thus in FIG 8 there is shown filaments 34 of layer 10D, filaments 35 of layer 10E, filaments 36 of layer 10F and filaments 37 of layer 10E.

In FIGS 9 to 11 there is shown a different arrangement of overlapping panels to that shown in FIGS 6 to 8 wherein again there are provided overlapping panels 10E, 10F and 10G in relation to base panel 10D.

However within central region 30 of the mesh assembly 31 as indicated in

FIG 11 by the arrow in full outline each of layers 10E and 10F have uncut corners to thereby reduce the overlap within region 30 to two layers of mesh. In FIGS 12 to 14 there is shown another alternative arrangement of overlapping panels 10D, 10E, 10F and 10G wherein in this embodiment each of panels 10D to 10G are provided with diagonal filaments 34A, 35A, 36A

and 37A.

FIG 14 shows central region 30 of mesh assembly 40 showing that there is a four layer overlap similar to what is shown in FIG 7. FIG 13 shows the overall location of each of panels 10D, 10E, 10F and 10G in relation to each other.

Any suitable moulding process may be used for manufacture of the reinforced mesh of the invention which may include injection moulding, compression moulding or rotational moulding. Suitably in one form an injection mould may include one part having a mould aperture that corresponds to the mesh of intersecting filaments and the stem or leg of the support or the frame of the support. Another mould part may have a mould aperture that corresponds to the enlarged base or foot of the support. Alternatively another mould part may be the integral support in the form of a body having a plurality of wings or legs and a foot. Clearly when both mould parts are in abutting relationships and pressurised plastics fluid is injected into the resulting entire or total mould aperture the reinforcement mesh of the invention may be manufactured.

It will be appreciated that the plastics reinforcement mesh of the invention will have substantial advantages over the conventional metal fabric mesh which include the following:

(i) it is lighter and therefore easier to carry,

(ii) it won't cause injury because there are no sharp points or edges or outwardly projecting lugs;

(iii) it is easier to cut, i.e. by using pliers or tinsnips rather than bolt cutters;

(iv) the mesh is at a constant height above the ground or other suitable support surfaces; and

(v) the mesh will not corrode and thus will not cause cracks in the concrete which happens with the metal fabric mesh which will be wetted by the wet concrete in the initial concrete pouring operation.