AU2010226913A1 - Reinforced shell for swimming pools - Google Patents

Description

P/00/011 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "REINFORCED SHELL FOR SWIMMING POOLS" The following statement is a full description of this invention, including the best method of performing it known to us: 1 TITLE "REINFORCED SHELL FOR SWIMMING POOLS" FIELD OF THE INVENTION 5 The present invention relates to shells for use in swimming pools, spas and similar arrangements. The invention more particularly relates to a method of reinforcing a shell for a swimming pool, spa and the like and a shell formed according to that method. BACKGROUND OF THE INVENTION 10 Swimming pools have been traditionally formed from concrete poured and/or sprayed into an excavation in the ground. With the advent of modern synthetic materials such as fibreglass, it became possible to provide a lightweight shell with high strength to weight characteristics for a swimming pool, spa or the like. In this context "fiberglass" is understood to refer to 15 composite materials more accurately known as glass fibre-reinforced polymer or glass-reinforced plastic. As manufacturing techniques improved, the size or complexity of such shells increased. Manufacturers may provide a synthetic shell for in-ground installation or above-ground installation, particularly for spas. While the 20 majority of the discussion in the specification is directed to swimming pools it is to be understood that other like structures such as spas are also within the scope of the present invention. There are however a number of problems that arise with the use of synthetic materials such as fibreglass for swimming pool shells. There are a 25 number of stress lines and points in shells, especially where panel sections such as walls and the floor meet. In a rectangular pool for example, two wall sections and the floor meet at a bottom corner. With increasing complexity of shape, often for aesthetic reasons, the stress areas increased in number. As a further factor, an issue arises with increasing depth in a pool as 30 the hydrostatic pressure of the water column applies a consistent and considerable pressure to the lower regions of the pool shell, also resulting in a stress area.

2 These stress areas may be vulnerable to cracking or weakening in a number of situations including manufacture itself, transport, installation and during the life of the pool when movement or pressure results in leaks. SUMMARY OF THE INVENTION 5 In one form although it need not be the only or indeed the broadest form, the invention resides in a method of manufacturing a reinforced composite shell for use as a swimming pool, spa or similar, the method comprising the steps of: (a) forming a shell in or on a mould; 10 (b) applying at least one reinforcing section to the shell; wherein (c) the at least one reinforcing section comprises a composite material including a plurality of high performance fibres. Forming the shell preferably comprises forming the shell primarily from fiberglass in conventional fashion. Applying the at least one reinforcing 15 section to the shell includes applying the reinforcing section to or into one or more of a wall, a floor, step sections and feature sections. The step of forming the shell preferably further comprises applying the at least one reinforcing section to the shell intermediate two layers. The reinforcing section may be applied to preferably one or more of junctions of 20 walls, the floor, the steps and feature sections. Applying the at least one reinforcing section preferably comprises applying a band of the composite material in the section or sections selected. A plurality of reinforcing sections may be applied to the shell. High performance fibres are to be understood as having one or more 25 characteristics superior to glass fibres. The high performance fibres may include one or more aramid fibres (including para-aramid fibres) carbon fibres and basalt fibres. The preferred section or sections for reinforcing may be selected from wall to wall junctions, wall to floor junctions, coping to wall junctions, step 30 section junctions to wall, pool features such as shallow sections and junctions to wall and/or floor as well as panels of the shell. In a further form, the invention may reside in a shell for a swimming 3 pool and the like, the shell formed according to the above method. In yet a further form, the invention may reside in a shell for a swimming pool and the like, the shell including at least one composite fibre reinforcing section, the at least one reinforcing section including a plurality of 5 one or more high performance fibres in a composite material. The reinforcing section/s applied to one or more sections of the shell may be formed from a material including a plurality of substantially parallel fibres and a resin. The reinforcing section may include one or more of carbon fibres, aramid fibres and basalt fibres. 10 A preferred material for the at lest one reinforcing section comprises a woven material formed from glass fibres with interspersed carbon fibres, aramid fibres and basalt fibres. The aramid fibres are preferably Kevlar@. The glass fibres may be E-glass fibres. 15 BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a schematic representation of production of a shell according to the present invention; FIG. 2 is a perspective view of a shell for a swimming pool manufactured according to the method of the present invention; and 20 FIG. 3 is a top view of a woven material suitable for use in a reinforcing section. DETAILED DESCRIPTION OF THE FIGURES Referring to FIG. 1, there is a seen a schematic outline of process 25 steps for a shell of the present invention. The production arrangement includes a mould at a station, 1, where a first step ("a first pass") is executed. Initially a layer of gelcoat is applied to the mould. Swimming pool shells are typically formed on an outside surface of the mould. The gelcoat is most commonly a blue colour but this may vary. It is 30 applied in a layer of approximately 0.5 - 1 millimetre. One example of a suitable material is FGI Gelcoat. This is a composition including styrene, fumed silica, pigments and extenders, synthetic resin, hydroxyethyl 4 methacrylate and dibutyl maleate. Other minor ingredients may also be included. At step 2, a second pass is completed. The outer side of the gelcoat is sprayed with a chopper gun. This device is driven by compressed air and 5 delivers a resin, a catalyst and chopped glass fibres. The resin is usually a vinyl ester resin such as VIPEL FOIO-LSE Resin - 45. This comprises styrene and synthetic resin. An example of a suitable catalyst is SUPEROX 46-701 which comprises methyl ethyl ketone peroxide, dimethylphthalate, hydrogen 10 peroxide and methyl ethyl ketone. The glass fibres are produced from gun rovings passed through rotating blades on the gun and introduced into the mixture of catalyst, resin and air. The layer applied at this pass is usually around 2mm thick and is rolled to even it out and remove air. 15 A third pass (3) is made wherein the mixture is applied to radii only. In this case the resin used is typically an orthothalic resin. A suitable example is 6060-75 WH LSE. The composition includes styrene monomer, polyester resin, quinine and/or phenolic inhibitors and amine and/or aniline derivatives. This resin allows economic addition of thickness and strength. 20 The gun roving is also known as continuous filament fiberglass. Typically the composition comprises around 95% fibrous glass (E-glass, continuous filament) and organic surface binder or sizing. In this pass, woven rovings of fiberglass are layered onto radii of the shell after they are sprayed with orthothalic resin, catalyst and gun rovings. 25 Once laid, the woven rovings are oversprayed again with the same combination. In the present invention, one or more reinforcing sections with a plurality of high performance fibres are now, preferably, fixed in position. A preferred material is a woven glass product including aramid fibres and/or 30 carbon fibres and/or basalt fibres and/or ECR glass in a woven and/or non woven form. Preferred glass may comprise ECR glass which is similar to E glass but without boron fluorine. This improves and provides the product 5 with additional strength. The aim is to form a composite material which are engineered materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct 5 on a macroscopic level within the finished material. In the present case, composites are considered to include fibre reinforcement surrounded by plastic or other binder. In this specification, the term composite may, where the context allows, also refer to the fibrous, preferably woven reinforcing material including at least one high performance 10 fibre. One suitable material comprises a woven glass base with longitudinal multi strand carbon fibres and angled strands of a aramid fibre such as Kevlar@. The material may be placed onto the pool shell after a priming layer of catalyst and resin and subsequently have additional catalyst and resin 15 applied to saturate the material and provide, ultimately after setting, a high strength composite reinforcing section with high performance fibres. In an alternative embodiment, the high performance fibres may be purely aramid or basalt fibres or a combination of the two. A knitted fabric incorporating high performance fibres may be used. 20 A further pass (4) is made using orthothalic resin, gun roving and catalyst. At this stage strengthening ribs are applied in selected positions such as along the wall and closed box reinforcement sections are also applied before a final pass (5) is made with orthothalic resin, gun rovings and 25 catalyst. Standard additions including lifting points for movement of the shell, stainless end wire ties for attachment to steel reinforced concrete are included in the shell. Preferably multiple reinforcing sections are applied such as at 30 the joins between two walls, the walls and the floor and other sections if required. These other sections may be any part of the shell but typically would extend from joins between sections such as walls, floors, steps, 6 features or other structures. It may be desirable to apply reinforcing sections to straight and/or curved panel areas formed with more aesthetically directed shapes such as billabong, kidney or tear-drop shaped pools. The composite fibre reinforcing material is preferably applied internally in the shell and then 5 activated to set. A particularly preferred material will include reinforcing aramid fibres. In some embodiments the reinforcing sections may be applied externally. Aramid fibres form a core of heat resistant and strong synthetic fibres. They are typically used in the aerospace industry and military applications. 10 The name is a shortened formed of aromaticpolyamide. The chain molecule has chemical characteristics for which the fibre can be exploited. The aramid fibres are able to be handled similarly to normal textile clothing fibres and are characterised by their excellent resistance to heat as they neither melt nor ignite in normal levels of oxygen. The expression aramid fibres should be 15 understood to extend to variants and analogs such as a meta-aramid. Aramid fibres also include the well known trade named product Kevlar@ which is a trade mark of Dupont. This material combines high strength with lightweight to improve the performance of the present reinforcing sections. Kevlar@ is lightweight, flexible, strong and safe. 20 The fibres may also be selected from the carbon fibre group of materials. These are also known as graphite fibre or carbon graphite and form a material consisting of extremely thin fibres and composed mostly of carbon atoms. Typically the fibres will be in a range of around 0.005 to 0.010mm. The carbon atoms are bonded together in a way that more or less 25 aligns them parallel to the long axis of the fibre. The crystal alignment makes the fibre very strong for its size. Several thousand carbon fibres are twisted together to form a yarn, which may be used by itself or woven into a fabric. Carbon fibre has many different weave patterns and is usually combined with a plastic resin and wound or moulded to form composite materials. This 30 carbon fibre reinforced plastic (also referenced as carbon fibre) provides a high strength to weight material. The density of carbon fibre is also considerably lower than the density of steel making it extremely strong for its 7 weight. The properties of carbon fibre include it being high tensile, low weight and low thermal expansion. Basalt fibres are made from extremely fine fibres of basalt, comprising the minerals plagioclase, pyroxene and olivine. It has better 5 physiomechanical properties than fibreglass. Fibres typically have a diameter between 9 and 13 micrometres. The fibres are produced by extruding molten basalt. One preferred embodiment of composite fibre reinforcing material is a knitted fabric material which is applied to some of the swimming pool shell 10 and is wet through with a resin. Referring to FIG. 2 there is a seen a shell 20 comprising a floor 21 a side wall 22 and end wall 23. The walls 22, 23 terminate in an upper lip 24 which extends around the pool top surface. The present alignment shows a shell during manufacture when it is inverted on a mould and allows access to stress sections such as wall to wall junctions 25, 15 wall to floor junctions 26 and other areas such as formation of steps, curves, shall sections or "beaches" which are not shown in this view. A composite fibre reinforcing section 28 is shown and positioned along the adjoining paneled sections such as walls and floors. FIG. 3 shows a preferred woven material for use in reinforcing 20 sections. The material 30 comprises woven strands based on a glass fibre 32 mat. A preferred glass fibre is E-glass. The mat is interspersed with three high performance fibres. Broad bands of carbon fibre 34 are spaced evenly through the mat. Transverse to the carbon fibres 34 are Kevlar@ fibres 36. Parallel to 25 the Kevlar@ fibres 36, and positioned between adjacent Kevlar® fibres, are basalt fibres 38. This material in itself is considered novel and inventive. The composite fibre reinforcing section is positioned preferably as a woven band into position with a resin which impregnates the material and 30 sets to incorporate it into a solid reinforcing section adhered to shell 20. The preferred method is incorporation of the reinforcing section internally in the walls as they are layered. Further layers may be applied. The reinforced shell 8 is allowed to dry completely and obtain full strength. It is then moved by appropriate lifting gear such as a crane, a forklift or pulley system onto a transport vehicle for transfer to a an installation site. On site the pool shell is arranged in an excavation or alternatively as 5 an above ground pool typically with a surround support wall. Water is then added along with the appropriate plumbing for filtration purposes. The shell of the present invention once in place and filled is highly resistant to cracking due to the application of the present invention. The present invention provides numerous advantages. One particular advantage 10 is the increased strength of the pool shell to resist fracture and leakage. The present invention provides a safe long lasting and strengthening addition to a traditional pool shell. The composite fibre reinforcing section is reasonably expected to extend the life of the shell and to avoid manufacturing defects and faults especially at the stress sections of a pool shell. 15 Throughout the specification the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment or specific collection of features. It will therefore be appreciated by those of skill in the art that, in light of the instant disclosure, various modifications and changes can be made in the particular 20 embodiments exemplified without departing from the scope of the present invention.

Claims (17)

1. A method of manufacturing a reinforced composite shell for use as a swimming pool, spa or similar, the method comprising the steps of: 5 a) forming a shell in or on a mould; b) applying at least one reinforcing section to the shell; wherein: the at least one reinforcing section comprises a composite material including high performance fibres. 10

2. The method of claim 1 wherein applying the at least one reinforcing section to the shell includes applying the reinforcing section to or into one or more of a wall, a floor, step sections and feature sections. 15

3. The method of either claim 1 or claim 2 wherein the step of forming the shell further comprises applying the at least one reinforcing section to the shell intermediate two layers of the shell.

4. The method of any one of the preceding claims wherein the at least 20 one reinforcing section is applied to one or more of junctions of walls, the floor, the steps and feature sections.

5. The method of any one of the preceding claims wherein applying the at least one reinforcing section comprises applying a band of the composite 25 material in the section or sections selected.

6. The method of any one of the preceding claims wherein the high performance fibres have one or more characteristics superior to glass fibres. 30

7. The method of any one of the preceding claims wherein the high performance fibres comprise one or more of aramid fibres, carbon fibres and basalt fibres. 10

8. The method of any one of the preceding claims wherein the composite material includes a combination of glass fibres, aramid fibres, basalt fibres and carbon fibres. 5

9. The method of claim 8 wherein the combination of fibres is formed as a woven material having carbon fibres, aramid fibres and basalt fibres woven through a woven glass fibre mat.

10 10. A shell for a swimming pool, spa or similar, the shell including at least one composite material reinforcing section, wherein the composite material includes a plurality of one or more high performance fibres.

11. The shell of claim 10 wherein the high performance fibres comprise 15 one or more of carbon fibres, aramid fibres and basalt fibres.

12. The shell of either of claims 10 or 11 wherein the composite material includes a woven fibre glass mat with bands of carbon fibres, aramid fibres and basalt fibres woven into the fibre glass mat. 20

13. The shell of claim 12 wherein the aramid fibres comprise Kevlar.

14. The shell of any one of claims 10 to 13 wherein the at least one composite material reinforcing section is located at one or more of: 25 a) wall to wall junctions; b) wall to floor junctions; c) coping to wall junctions; d) step section junctions to a wall or walls; and e) pool features namely shallow sections, junctions to walls and 30 floors or panels. 11

15. A method of manufacturing a reinforced composite shell for use as a swimming pool, spa or similar substantially as described herein with reference to FIG. 1. 5

16. A reinforced composite shell for use as a swimming pool, spa or similar, the reinforced shell substantially as described with reference to FIGS. 1 and 2. 10

17. A woven material for use in reinforcing composite shells substantially as described with reference to FIG. 3