AU2006225280A1 - Decorative wall panelling - Google Patents

Description

AUSTRALIA

AUSTRALIA

Patents Act 1990 ROBERT GONDA COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Decorative wall panelling The following statement is a full description of this invention including the best method of performing it known to us:- O 2 Cross-Reference to Related Applications

C.)

0 o The present application claims priority from Australian Provisional Patent O Application No 2005905558 filed on 7 October 2005, the content of which is incorporated herein by reference.

00 N, Field of the Invention (Ni INO The present invention relates to a panel for use in building construction. In particular, the present invention relates to decorative wall panels and a method of making such a panel having an appearance of natural stone for decorating surfaces in architectural environs.

Background of the Invention Stones, rocks and other types of naturally occurring materials have long been used in building construction. In many instances, the workmanship of the stone used in various constructions has been used to define a certain period of architectural design, which is synonymous with a period of history.

In this regard, the general appearance of a stone or rock surface, particularly one that has been hand carved or hand designed, conveys a certain visual and tactile appeal.

Typically, such an appeal is highly desirable in the design and construction of buildings to convey an inherent strength and natural feel to the construction. This is particularly important in an age of modem and light weight building designs which typically comprise plastics and plasters, as such constructions do not typically convey the same appeal as hand carved stone.

However, in many instances it is not practical to employ natural stone in a building structure due to the high cost of the material, as well as the amount of labour required to prepare, handle and assemble the material. For this reason, it has been known to provide surface coverings, such as tiles or panels, which can be attached to a surface of a building or structure to convey the appearance of a natural stone surface.

Existing tiles/panels intended for this purpose are typically mass processed and as such do not capture the natural appeal of hand carved stone. Those tiles/panels m:\speci\l 30000\1 30-131 \130217cmpgpd.doc IND 3 which use pieces of stone material in order to create a natural look are typically too o heavy or inflexible to employ in many situations and hence are limited in their use.

SIn this regard, there is a need to provide a decorative wall panel system that emulates the visual and tactile appeal of hand carved stone but is neither cost nor 00 weight prohibitive and which is light weight and flexible to suit a variety of uses both 00 ,IC externally and internally.

IND Summary of the Invention Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

According to a first aspect, the present invention is a panel for covering a surface of a structure comprising: a body having a first surface configured to resemble a stone surface and a second surface arranged to be secured to said surface of the structure; wherein the body comprises from about 40-80% by weight of calcined gypsum and from about 10-40% by weight of a polymeric binding agent.

In an embodiment of this aspect of the invention, the calcined gypsum is alpha calcium sulphate hemihydrate. In one form, the body may comprise about 50-70% of the alpha calcium sulphate hemihydrate. In another embodiment, crystalline silica may be added to the calcined gypsum to improve durability and texture of the panel. In this regard, the crystalline silica may be added up to a maximum of 50% of the weight of the calcined gypsum.

In another embodiment, the polymeric binding agent is in the form of a two-part binding agent. A first part of the two-part binding agent may be an acrylic co-polymer.

The acrylic co-polymer may be in the form of a cross-linkable acrylic copolymer emulsion. The acrylic co-polymer may be acrylic latex, such as polyacrylic acid latex.

In this regard, the body may comprise about from about 5-20% by weight of the acrylic co-polymer. A second part of the two-part binding agent may be in the form of a thermoplastic polymer material. The thermoplastic polymer material may be a m:\speci\1 30000\1 30-131 \1 30217cmpgpd.doc INO 4

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thermoplastic resin selected from any one of the following groups: polyethylenes, O polyamides, polycarbonates, polypropylene and ethylene-vinyl acetates. In one form IDthe thermoplastic polymer material is an ethylene co-polymer such as ethylene vinyl Sacetate. In this regard, the ethylene vinyl acetate may be in an emulsion form which cross-links with the first part of the polymeric binding agent. In this regard, the body 00may comprise from about 5-20% by weight of the thermoplastic polymer material. In C another embodiment, the body comprises the first part and the second part of the two- C1 part binding agent in relatively equal proportions.

IND

In another embodiment, the body further comprises aggregate material to increase the strength of the panel. The aggregate material may be in the form of a plurality of hollow ceramic spheres. The spheres may have particle sizes ranging from to 150 microns. The body may comprise from about 5-15% by weight of the aggregate material. In one form, the body comprises about 8% by weight of the aggregate material.

In another embodiment, the body further comprises a plurality of glass fibres provided therein. The glass fibres may be provided between the first and second surfaces of the body, such that they are embedded within the body. In this regard, the glass fibres may be arranged to form a layer of glass fibres embedded within the body of the panel.

In yet another embodiment, the first surface of the body may be configured by means of a casting operation to resemble the stone surface. In this regard, the first surface may comprise a plurality of grooves or markings typical of a look and texture of hand carved stone. The second surface of the body may be formed to be substantially flat to enable the panel to be mounted to a surface of the structure.

According to a second aspect, the present invention is a method of forming a panel for covering a surface of a structure, comprising: forming a composition comprising from about 40-80% by weight of calcined gypsum and from about 10-40% by weight of a polymeric binding agent; adding a first portion of said composition into a mould, said mould corresponding to a shape of the panel to be formed and said first portion being less than the capacity of said mould; applying a reinforcing agent to said portion of added composition; and m:\speci\130000\1 30-131\1 30217cmpgpd.doc INO adding a final portion of said composition into the mould to form said panel.

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In one embodiment of this aspect of the invention, the composition is formed by introducing the calcined gypsum and the polymeric binding agent into a mixing vessel.

In this regard, the polymeric binding agent may be introduced into the mixing vessel in Sthe form of an aqueous solution. The composition may also comprise a colouring agent 00 N and/or a defoaming agent which are introduced into the mixing agent according to Vt) Cdesired proportions. In this regard, the defoaming agent may be in the form of an ,O aqueous solution which forms from about 0-1% by weight of the composition. The colouring agent may also be in the form of an aqueous solution that forms from about N 0-10% by weight of the composition. The composition may also comprise water which is added to the mixing vessel to form about 3-10% by weight of the composition.

Further, the composition may comprise aggregate material which is added to the mixing vessel in solid form so as to form about 5-15% by weight of the composition.

In another embodiment, the composition may be formed by firstly adding the aqueous components, for example, the binding agent, colouring agent, defoaming agent and water to the mixing vessel. The aqueous components may be mixed together to form an aqueous solution. Following mixing of the aqueous components, the calcined gypsum may be added to the aqueous solution and mixed therewith. Following addition and mixing of the calcined gypsum with the aqueous solution, the aggregate may be added and mixed to form the composition.

The mould may be a flexible mould having an internal space which defines the shape of the panel. In this regard, the mould may be made from a silicone material.

The internal space of the mould may comprise a base surface having contours and/or patterns formed therein to form an external surface of the panel.

In one embodiment, the first portion of the composition is added to the mould such that it substantially covers the base surface of the mould. In one form, a brush and/or wiper may be used to spread the first portion of the composition across the base surface of the mould. The brush and/or wiper may apply force to the first portion of the composition to ensure that the composition is urged into the contours and/or patterns formed in the base surface of the mould. The brush and/or wiper may also release air bubbles entrapped within the composition.

m:\speci\1 30000\1 30-131\130217cmpgpd.doc O 6 The reinforcing agent may be in the form of glass fibres which may be applied Sto an exposed surface of the added first portion of the composition. In this regard, the O ,O glass fibres may be arranged to form a layer of fibres that extends across the exposed O surface of the first portion of the added composition. In one form, the glass fibres may be in the form of a mat of glass fibres. In another form, individual glass fibres may be 0 evenly spread across the exposed surface of the first portion of the composition.

00 In yet another embodiment, the final portion of the composition is added to the O mould such that it evenly covers the reinforcing agent applied to the first portion of the composition. In this regard, the composition may be added such that it substantially ,I fills the internal space of the mould to the desired thickness of the panel. Following addition of the final portion of the composition, the composition may be allowed to settle for an initial period. This initial period may be approximately two minutes.

Following expiration of this period, the composition may be levelled by a scraping device to remove excess composition from the mould. The composition may then be allowed to cure for a period prior to removal of the panel from the mould. The panel may then be removed from the mould by peeling the mould from the panel.

In still another embodiment, following removal of the panel from the mould, a sealant coating may be applied to the panel. The sealant coating may provide a barrier around the panel to prevent moisture from contacting the composition of the panel. In this regard, the sealant coating may be a silicone sealant coating.

Brief Description of the Drawings By way of example only, the invention is now described with reference to the accompanying drawings: Fig. 1 shows plan and cross-sectional views of a variety of panels in accordance with an embodiment of the present invention; Fig. 2 is a flow chart showing the steps associated with forming the panels of Fig. 1; and Fig. 3 is a partial cross-sectional view showing the panels of Fig. 1 fixed to a wall structure during use.

m:\speci\1 30000\130-131\1 30217cmpgpd.doc IND 7

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Detailed Description of an Exemplary Embodiment of the Invention 0 SReferring to Fig. 1, there is shown a variety of styles of panels 10, in accordance 0 with various embodiments of the present invention. As is shown, each of the panels has an external surface 12 which is textured to represent a natural stone surface. The 0 texture of the external surface 12 can vary according to the specific design needs of the

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C environment in which it is to be used, as will be discussed in more detail later in the description. Each of the panels 10 also have a backing surface 14 for mounting the IND panel 10 to a structure, such as a wall of the building, as will also be discussed later in the description. It will be appreciated that the panels 10 of the present invention are suitable for a variety of interior and exterior uses, particularly where natural stone is either weight or cost prohibitive. In this regard, the panels 10 are lightweight and the external surface 12 thereof provide both the visual and tactile appeal of hand carved stone.

Each panel 10 is made from a composite material that is a mixture of calcined gypsum, a binding agent and a reinforcing agent, to form a material that can be readily fitted to a building or the like for interior and exterior applications. The panel 10 has high tensile and impact strength, good elongation properties and is resistant to flex, cracking and fatigue thereby ensuring that it can be readily used in a variety of building situations. Further to this, each panel 10 can be formed to assume a variety of natural or hand carved stone profiles, as shown in Fig. 1, and with the addition of colour additives, provides a panel 10 that replicates the appearance of a variety of natural stones, such as sandstone, bluestone and the like.

The calcined gypsum may be in the form of an alpha-hemihydrate calcium sulphate. Such a plaster has much lower water requirements than that present in typical Beta grade plasters. Alpha-hemihydrate plaster has very fine particle size with well formed crystals and hence can be easily moulded to accurately reproduce the characteristics of a surface mould to which it is applied. As a result of this, alphaplasters yield low porosity and high mechanical strength when cast with water.

To provide additional durability and improved texturing of the panel 10, silica sand is added to, or applied on, the plaster. The silica sand may have a maximum diameter of 0.5mm and may be added to a maximum of 50% of the weight of the gypsum. It will be appreciated that the amount and type of additives added to the m:\speci\l 30000\1 30-131 \130217cmpgpd.doc IO 8 Splaster will typically be dependant upon the desired properties of the panel 10 to be o cast.

SThe binding agent used to form the panel 10 of the present invention is a twopart binding agent. The first part is a high-grade acrylic co-polymer which enables the Spanel 10 to exhibit high flexural and impact strengths. The co-polymer may be an acrylic latex, which includes polyacrylic acid latex. One type of binding agent suitable C for use is sold under brand name Forton® VF-812, which is made and distributed by N0 Forton B.V. of Sittard, Holland. which includes polyacrylic acid co-polymer and may be a methacrylic type of water based co-polymer in the form of a cross-linkable acrylic co-polymer emulsion in aqueous form. This co-polymer dispersion contains small polymer particles, with an average particle size of 225 nm which are held buoyant in the aqueous solution in emulsion form.

The second part of the binding agent is a thermoplastic additive that is added to the mixture. The thermoplastic additive may be a thermoplastic polymer material such as a thermoplastic resin selected from any one of the following groups: polyethylenes, polyamides, polycarbonates, polypropylene and ethylene-vinyl acetates. In this regard, the thermoplastic additive may be an ethylene vinyl acetate emulsion that cross links with the first part of the binding agent to combine to form a product with increased flexibility, greater elongation characteristics, high impact and tensile strength and greater durability.

As will be discussed in more detail below, the ingredients are mixed together for pouring into a mould and as such air bubbles may form in the mixture upon agitation and pouring. Such air bubbles are undesirable as they may form air pockets or voids in the panels 10, thereby compromising the strength and appearance of the final panels In order to minimize the formation of air bubbles in the mixture, a defoamer/antifoaming agent may be added.

Additional aggregate material may also be added to the mixture to increase the mechanical strength of the mixture without increasing its weight. In this regard, during mixture of the components, hollow, ceramic spheres or micro balloons made by a high temperature baking process may be added to the mixture for this purpose. The spheres may have particle sizes ranging from 20 to 400 microns.

m:\speci\130000\130-131\130217cmpgpd.doc NOD 9 As alluded to above, a colouring agent can also be added during the mixing o process to colour the mixture to form a panel 10 that replicates a type of rock or stone I surface. In this regard, for a bluestone appearance a blue or black colour additive may Sbe used to provide the appropriate appearance of a bluestone. Similarly, for other coloured stones, other colour additives may be also employed to replicate the natural Sstone colour.

00 CN As shown in the table below, the components are mixed in accordance with the \0 shown weight percentages:

N

Component Item w/w Plaster Alpha Plaster (FGR-95) 40-80 Binding agent 1 Co-polymer (Forton® VF-812) 5-20 Binding Agent 2 EVA 5-20 Water 3-10 Defoamer Commercial antifoaming agent 0-1.0 Colouring Agent Inorganic pigments 0-10 Aggregate micro balloons 5-15 As will become apparent during the description of the moulding procedure below, glass fibres are also used within the mixture to act as a reinforcing agent. The glass fibres are added during the moulding process and it will be appreciated that the glass fibres provides the material with much of its strength and assists in combining the plaster and binding agents. Thus ensuring that the material has greater strength and durability impact during use.

It will be appreciated that the ranges of concentrations of the components will be largely dependent upon the type of panel 10 being replicated. For instance, for a blue stone appearance panel, it will be necessary to add significantly more colouring agent than is required for a panel of ivory stone appearance. Similarly, the amount of plaster added may vary depending on the type of panel being used and its intended use. As will be appreciated, the concentration of the binding agents is typically the same to ensure sufficient cross-linkage of the components.

The process 20 for forming the panels 10 will now be discussed in relation to Fig. 2.

m:\speci\130000\1 30-131\130217cmpgpd.doc INO 0 The manner in which the ingredients are mixed together in the mixing step 22 is 0 important to ensure that the mixture is of a sufficient texture and viscosity to enable the mixture to be moulded into the desired form. In this regard, the liquid components, namely the binding agents together with the defoamer and any colour additive that may be necessary, are firstly mixed together in a mixing container and agitated at a slow 00 N, speed for approximately 30 seconds.

,IAfter this point, the plaster is progressively added to the liquid mixture and as the plaster is added the speed of the agitation is increased. Once the plaster has been i completely added into the mix, the entire mixture is then agitated for 2 minutes, after which the additional aggregate is added and mixed into the mixture for a further 1 minute. The mixture is then ready for the pouring step 24.

As alluded to above, it will be appreciated that the panels 10 of the present invention are created by pouring the mixture into a mould which resembles the shape of the final panel. In this regard, the external surface 12 of the panel 10, which is the exposed surface of the panel 10 during use, is formed to resemble the visual and tactile appeal of a hand carved stone such as a granite, blue stone or natural stone.

In order to achieve this natural stone appearance, it is important that the mould, and in particular the portion of the mould that corresponds to the external surface 12 of the panel 10, is carefully crafted to reproduce the desired appeal of the stone. This is achieved by creating a plug from the same material as the final panel which is intended to resemble the final panel The plug is essentially made from a blank mould of material, to the size and thickness of the desired final panel. In this regard, it can be considered that the plug is a hand crafted panel. The external surface of the plug is hand carved to form the desired surface pattern and texture, to resemble a rock surface, as is shown in Fig. 1.

This hand carving of the surface may be performed by an artist to capture a natural surface texture and look which cannot be reproduced naturally through cutting and grinding machines.

Once the plug has been formed it is then secured to a flat surface to prevent the plug from warping or buckling over time, to enable multiple use of the plug to preserve m:\speci\l 30000\1 30-131\1 30217cmpgpd.doc S11 Sconsistency between final panels 10. The flat surface may be a stainless steel surface O which is machined to form a level surface onto which the plug is fixed such that the INO plug extends from the level surface. This arrangement forms a male mould for Sgenerating a plurality of female moulds into which the mixture is to be poured.

00 The female moulds are formed from a flexible material, such as silicone. The 00 I silicone is essentially poured over the male mould, and is urged around the plug, to form an internal space that assumes the shape of the external surface of the plug and the IDdesired thickness of the plug. Once the silicone has cured, it is removed from the male mould to form a mould into which the mixture may be poured, which will be an exact replica of the plug.

In step 24, the prepared mixture, as described in relation to step 22, is initially poured into the female mould to cover the entire bottom surface of the mould, including the contours and patterns formed therein, which will be the external surface of the panel that resembles an exposed rock surface. As the mixture is poured it is dispersed across the mould to ensure that the mixture is evenly spread. A brush or wiper may be used to assist in spreading of the mixture across the mould as the mixture is being poured.

Following the initial pouring step 24, the poured material is treated 26 to remove any bubbles that may be present therein and to ensure that the mixture is received within all the crevices and patterns in the mould. This is important as any deformity in the surface of the panel is easily noticeable and may greatly affect the natural stone look and the structural integrity of the panel 10. The treatment 24 is performed by using a hard bristle brush which is smeared with force against the mixture and releases the air bubbles entrapped therein and urges the mixture against the mould.

Once the initial portion of mixture has been poured and the poured material treated 26 to remove any bubbles therefrom, a layer of fibreglass is placed over the surface of the mixture in step 28. As discussed previously, the fibreglass may be precut into specific sized strands or may be chopped and evenly spread across the surface of the mixture. This step 28 provides a reinforcing layer within the panel 10 to increase the bending strength and yield strength of the panel 10 in use.

The remainder of the mixture is then poured into the mould in step 30 and spread such that it evenly covers the layer of fibreglass, thereby wetting both sides of m:\spec\1 30000\130-131 \1 30217cmpgpd.doc IO 12 Sthe fibreglass. The mixture is poured such that it completely fills the mould and O following pouring is allowed to settle for approximately two minutes, after which the ISO mixture is levelled by a scraping device that extends across the full width of the mould.

0 In step 32, the mixture is allowed to cure. Following an initial curing period of Sapproximately 1 hour, the surface of the mixture is treated to remove any peaks or 00 protrusions and to clean the edges of the mould. Following a further curing period of IC 30 minutes, namely 90 minutes from ceasing pouring of the mixture, the panel can be ISO removed from the mould. As the mould is made from a silicone material, it is flexible and able to be carefully pulled away from the moulded panel 10, without requiring chiselling or the like. Following removal, the panel is then smoothed to remove excess material from the edges where it can then be stored on a horizontal shelf at a controlled temperature for a period of time, prior to shipment for use. This period of time may be a period of at least 2 days at room temperature, or may be overnight in a confined space at 50 degrees Celsius.

In order to provide extra protection to the formed panels 10, particularly against moisture and stains that they may experience during use, the panels 10 may be sprayed with a sealant coating, such as a silicone based sealant in step 34. The coating may be applied evenly to each of the faces of the panel thereby providing a coating of sealant that encapsulates the panel 10. By applying such a coating to the panels 10, the panels are able be used in a wet environment, such as in water features and the like.

As will be appreciated, the formed panels 10 will be replicas of the original hand crafted plug and as such will have a natural look that resembles a natural stone surface.

The specific sizes of the panels 10 can vary depending upon the particular application of the panels during use, but the panels may typically be of a rectangular shape of 600mm x 1795 mm, 600mm x 1195 mm or substantially square in shape 600mm x 600mm. Further, due to the nature of the panels 10, the panels 10 can be readily cut to a desired shape and/or size.

Due to the above described composition of the panels, each of the panels weigh, 2 on average, around 10-15 kg/m 2 In this regard, and as is shown in Fig. 3, the panels can be easily attached to a structure 40, such as a substantially vertical wall, without requiring substantial anchoring bolts or the like, as is often the case with most decorative surface panels.

m:\speci\l 30000\1 30-131\130217cmpgpd.doc ND 13 The panels 10 may be attached to all types of structures 40 which are smooth INO and free of defects, such as rendered cement or plasterboard. As shown in Fig. 3, in the O event that the panels are to be applied to a non-smooth structure surface 40, the surface may require preparation prior to fixing the panels 10. In this regard, a substrate 42, Ssuch as a standard Gyprock® may be applied to the surface 40, with the substrate 42 00 having an MDF or plywood lamination finish 44, to provide the desired smooth i surface. The substrate 42 and finishing surface 44 may be secured to the surface of the IDstructure 40 by way of bolts or the like 43. The panels 10 may then be merely adhered to the finishing surface 44 by an appropriate adhesive 45 which secures the panels 10 in position upon the structure 40. The adhesive 45 could be a standard construction adhesive, such as a standard synthetic rubber based adhesive, which has sufficient strength to retain the relatively light-weight panels 10 in position.

As the materials used to make the panels 10 include acrylic co-polymers and thermoplastics in combination with alpha plaster, the panels made from this mixture of materials have superior tensile and flexural strengths than currently available building panels and result in an extremely lightweight product. Such properties increase the panel's resistance to impact forces and the like which are typical when handling such panels during assembly, and allow such panels to be employed in situations which were not possible with traditional imitation stone panels.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

m:\speci\1 30000\130-131\130217cmpgpd.doc

Claims (40)

1. A panel for covering a surface of a structure comprising: O a body having a first surface configured to resemble a stone surface and a second surface arranged to be secured to said surface of the structure; 0 wherein the body comprises from about 40-80% by weight of calcined gypsum 00 CN and from about 10-40% by weight of a polymeric binding agent.

2. A panel according to claim 1, wherein the calcined gypsum is alpha calcium sulphate hemihydrate.

3. A panel according to claim 2, wherein the body comprises about 50-70% by weight of alpha calcium sulphate hemihydrate.

4. A panel according to any one of the preceding claims, wherein the calcined gypsum comprises a quantity of crystalline silica. A panel according to claim 4, wherein said crystalline silica constitutes up to a maximum of 50% of the weight of the calcined gypsum.

6. A panel according to claim 1, wherein the polymeric binding agent is a two-part binding agent.

7. A panel according to claim 6, wherein a first part of the two part binging agent is an acrylic co-polymer.

8. A panel according to claim 7, wherein the acrylic co-polymer is in the form of a cross-linkable acrylic copolymer emulsion.

9. A panel according to claim 7 or 8, wherein the acrylic co-polymer is acrylic latex. A panel according to claim 9, wherein the acrylic latex is polyacrylic acid latex.

11. A panel according to any one of claims 7 to 9, wherein the body comprises about 5-20% by weight of the acrylic co-polymer. m:\speci\130000\130-131\130217cmpgpd.doc .)a O 12. A panel according to any one of claims 6 to 11, wherein the second part of the INO two-part binding agent comprises a thermoplastic polymer material.

13. A panel according to claim 12, wherein the thermoplastic polymer material O comprises a thermoplastic resin selected from any one of the following groups: polyethylenes, polyamides, polycarbonates, polypropylene and ethylene-vinyl acetates. I14. A panel according to claim 13, wherein the thermoplastic polymer material is an 0 ethylene co-polymer. A panel according to claim 14, wherein the ethylene co-polymer is ethylene vinyl acetate.

16. A panel according to claim 15, wherein the ethylene vinyl acetate is in an emulsion form which cross-links with the first part of the polymeric binding agent.

17. A panel according to any one of claims 12 to 16, wherein the body comprises from about 5-20% by weight of the thermoplastic polymer material.

18. A panel according to any one of claims 6 to 17, wherein the body comprises the first part and the second part of the two-part binding agent in relatively equal proportions.

19. A panel according to any one of the preceding claims, wherein the body further comprises aggregate material. A panel according to claim 19, wherein the aggregate material is in the form of a plurality of hollow ceramic spheres.

21. A panel according to claim 20, wherein the spheres have particle sizes ranging from 20 to 150 microns.

22. A panel according to any one of claims 19 to 21, wherein the body comprises from about 5-15% by weight of the aggregate material. m:\speci\130000\1 30-131\1 30217cmpgpd.doc INO 16 ,23. A panel according to claim 22, wherein the body comprises about 8% by weight C.) O of the aggregate material.

24. A panel according to any one of the preceding claims, wherein the body further comprises a plurality of glass fibres. 00 ,I 25. A panel according to claim 24, wherein the glass fibres are provided between ,IC the first and second surfaces of the body such that they are embedded within the body. \O IND

26. A panel according to claim 25, wherein the glass fibres are arranged to form a layer of glass fibres embedded within the body of the panel.

27. A panel according to any one of the preceding claims, wherein the first surface of the body is configured by means of a casting process to resemble the stone surface.

28. A panel according to claim 27, wherein the first surface comprises a plurality of grooves and/or markings to resemble a hand carved stone.

29. A panel according to any one of the preceding claims, wherein the second surface of the body is substantially flat to enable the panel to be mounted to a surface of the structure. A method of forming a panel for covering a surface of a structure, comprising: forming a composition comprising from about 40-80% by weight of calcined gypsum and from about 10-40% by weight of a polymeric binding agent; adding a first portion of said composition into a mould to at least partially fill the mould; applying a reinforcing agent to said first portion of said composition; and adding a second portion of said composition into the mould to substantially fill said mould and form said panel.

31. A method according to claim 30, wherein the step of forming the composition comprises introducing the calcined gypsum and the polymeric binding agent into a mixing vessel. m:\speci\1 30000\1 30-131 \130217cmpgpd.doc IND 17

32. A method according to claim 31, wherein the polymeric binding agent is O introduced into the mixing vessel in the form of an aqueous solution. O O 33. A method according to claim 31 or 32, wherein the step of forming the composition further comprises introducing a colouring agent and/or a defoaming agent 0 into the mixing vessel. 00 S34. A method according to claim 33, wherein the defoaming agent is in the form of an aqueous solution which comprises from about 0-1% by weight of the composition. 8 i 35. A method according to claim 33, wherein the colouring agent is in the form of an aqueous solution that comprises from about 0-10% by weight of the composition.

36. A method according to any one of claims 31 to 35, wherein the step of forming the composition further comprises adding water to the mixing vessel.

37. A method according to claim 36, wherein the water is added such that it forms about 3-10% by weight of the composition.

38. A method according to any one of claims 31 to 37 wherein the step of forming the composition further comprises adding aggregate material to the mixing vessel.

39. A method according to claim 36, wherein the aggregate material is added such that it forms about 5-15% by weight of the composition. A method according to claim 39, wherein the step of forming the composition comprises adding, the binding agent, colouring agent, defoaming agent and water to the mixing vessel and mixing said components to form an aqueous solution.

41. A method according to claim 40, wherein the calcined gypsum is added to the aqueous solution and mixed therewith.

42. A method according to claim 40 or 41, wherein the aggregate is further added to the aqueous solution and mixed to form the composition. m:\speci\l 30000\1 30-131 \1 30217cmpgpd.doc IND 18

43. A method according to claim 30, wherein the mould is a flexible mould having C.) o an internal space which defines the shape of the panel.

44. A method according to claim 43, wherein the internal space of the mould comprises a base surface having contours and/or patterns formed therein to form an 0 external surface of the panel. 00 A method according to claim 44, wherein the step of adding the first portion of IND the composition into the mould comprises adding the composition such that it substantially covers the base surface of the mould.

46. A method according to claim 45, wherein following addition of the first portion of the composition a brush and/or wiper is used to spread the first portion of the composition across the base surface of the mould.

47. A method according to claim 30, wherein the step of applying a reinforcing agent to the first portion of the composition comprises adding glass fibres to the first portion of the composition.

48. A method according to claim 47, wherein the glass fibres are added to an exposed surface of the first portion of the composition.

49. A method according to claim 48, wherein the glass fibres are arranged to form a layer of glass fibres that extends substantially over the exposed surface of the first portion of the composition. A method according to claim 49, wherein the glass fibres are in the form of a mat of glass fibres.

51. A method according to claim 49, wherein the glass fibres are individual glass fibres that are evenly spread across the exposed surface of the first portion of the composition.

52. A method according to claim 30, wherein the step of adding the second portion of the composition comprises adding the second portion such that it evenly covers the reinforcing agent applied to the first portion of the composition. m:\speci\1 30000\1 30-131 \130217cmpgpd.doc O 19 o 53. A method according to claim 52, wherein the second portion of the composition ,O substantially fills the internal space of the mould to form the desired thickness of the O panel.

54. A method according to claim 53, wherein following the step of adding the 00 second portion of the composition into the mould the composition is allowed to settle C for a settling period. O

55. A method according to claim 54, wherein following expiration of the settling period, the composition is levelled to remove excess composition from the mould.

56. A method according to claim 55, wherein following removal of the excess composition, the composition is allowed to cure for a period prior to removal of the panel from the mould. Dated this sixth day of October 2006 Robert Gonda Patent Attorneys for the Applicant: F B RICE CO m:\speci\1 30000\1 30-131 \1 30217cmpgpd.doc