WO2009030951A1

WO2009030951A1 - Artificial playing surface

Info

Publication number: WO2009030951A1
Application number: PCT/GB2008/050781
Authority: WO
Inventors: Robert Gillespie
Original assignee: Thompson, Gordon
Priority date: 2007-09-04
Filing date: 2008-09-04
Publication date: 2009-03-12
Also published as: GB2465535A; GB201005630D0; GB0717089D0

Abstract

An artificial playing surface (10) is provided. The playing surface (10) comprises a support layer (14) formed from one or more panels. Each panel includes a plurality of cells (18). The playing surface (10) also 5 comprises an artificial turf layer (16) laying upon an upper surface (13) of the support layer (14). A method of installing the artificial playing surface (10) is also provided. The installation method comprises forming an aggregate base layer 10 (12) and laying one or more panels upon the base layer (12) to form a support layer (14), where each panel includes a plurality of cells (18). The method is completed by laying an artificial turf layer (16) upon the support layer (14).

Description

ARTIFICIAL PLAYING SURFACE

The present invention is directed to the field of sports playing surfaces. More specifically, the invention is an artificial playing surface and a method for installing the surface.

Artificial playing surfaces have been presented for many years as the ideal alternative to real turf surfaces. Artificial surfaces require very little maintenance compared to real turf, and allow sports to be played during or immediately after weather that would make a real turf surface unplayable. Original artificial surfaces consisted of a compacted base layer made up of stone or other aggregate, a concrete or bitumen tarmac structural layer laid upon the base, a shock-absorbing layer of rubber or the like laid upon the concrete, and finally an artificial turf layer laid upon the shock- absorbing layer. The structural layer provided not only structural support but also determined the speed of the playing surface. In other words, the harder the surface the more speed players could gain on the surface as their energy was not being lost in a soft layer beneath the artificial turf. The presence of the base and structural layers necessitated the shock- absorbing layer, given that the natural cushioning of a real turf surface was not present.

An improved artificial surface has previously been proposed, which combines the support and shock-absorption functions in a single layer between the base and the artificial turf layer. This single composite layer is made up of plastic beads (e.g. polypropylene) which are bound together using a plastic binder (e.g. polyurethane). Due to this composition, the improved surface is highly permeable to water. Whilst this ensures that the artificial top layer is drained of any surface water quickly, the surface water passes very quickly to the drainage system laid below the surface. Following a heavy downpour, the drainage system can be swamped by the water passing directly through the composite layer at a much faster rate than if it were draining through soil below a real turf surface. This causes the water to back up onto the playing surface. Furthermore, the porosity of the improved surface means that it will require at least as many drainage pipes as a real turf playing surface to take away the water passed through the composite layer. Additionally, if the water table below the playing surface is caused to rise due to a local flooding event, the composite layer will allow water to quickly pass upwards through the surface, leaving the surface unplayable.

It is an aim of the present invention to obviate or mitigate one or more of the aforementioned disadvantages with existing artificial playing surfaces.

According to a first aspect of the invention, there is provided an artificial playing surface comprising: a support layer comprising one or more panels, wherein each panel includes a plurality of cells; and an artificial turf layer lying upon an upper surface of the support layer.

Each panel may be a honeycomb panel in which each cell is substantially hexagonal.

Each panel may have upper and lower faces and at least one of the faces may be covered with a non-woven fibrous sheet. Both the upper and lower faces of each panel may be covered by a non-woven fibrous sheet. The sheet may be non-woven polyester. The sheet may be thermowelded to the upper and/or lower faces. Each panel may be formed from a plasties material. The plasties material may be polypropylene.

Each cell may extend across the depth of the panel. Each cell is defined by a plurality of cell walls, where each cell wall may be at least 8mm long.

The support layer may comprise a plurality of adjoining panels and the playing surface may further comprise mechanical fixing means for securing the panels to one another.

According to a second aspect of the present invention, there is provided a support panel adapted to support a layer of artificial turf and form an artificial playing surface according to the first aspect of the invention.

According to a third aspect of the invention, there is provided a method of installing an artificial playing surface, comprising: forming an aggregate base layer; laying one or more panels upon the base layer to form a support layer, each panel including a plurality of cells; and laying an artificial turf layer upon the support layer.

The forming of the base layer may comprise levelling and compacting an existing aggregate layer. The existing aggregate layer may comprise red ash.

Alternatively, the forming of the base layer may comprise excavating a pit and laying a mixture of crushed rock and sand therein. The forming of the base layer may further comprise the steps of levelling and compacting the crushed rock and sand within the pit. The support layer may comprise a plurality of adjoining panels and the method may further comprise securing the panels to one another using mechanical fixing means.

Each panel may be a honeycomb panel in which each cell is substantially hexagonal. Each panel may have upper and lower faces and at least one of the faces is covered with a non-woven fibrous sheet. Both the upper and lower faces of each panel may be covered by a non-woven fibrous sheet. The sheet may be non-woven polyester. The sheet may be thermowelded to the upper and/or lower faces.

Each panel may be formed from a plastics material. The plastics material may be polypropylene.

Each cell may extend across the depth of the panel. Each cell is defined by a plurality of cell walls, wherein each cell wall may be at least 8mm long.

A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawing, in which Figure 1 shows an exploded cross section through an artificial playing surface.

An artificial playing surface in accordance with the present invention is shown in Figure 1 and generally designated 10. The surface 10 comprises a support layer 14 and an artificial turf layer 16 laid upon the upper surface of the support layer 14.

The support layer 14 is formed from one or more honeycombed plastic panels. The honeycomb is formed from a plurality of substantially hexagonal cells 18 which extend across the depth of the panel between upper and lower faces 13,15 of each panel. It is preferable, though not essential, that at least one face 13,15 is covered by a non-woven fibrous sheet 20. In the non-limiting illustrated example, the non-woven sheet 20 is formed from polyester. Both upper and lower faces 13,15 may be covered by the sheet 20. If present, the sheet 20 is thermo-welded to the face(s) 13,15.

The panels themselves are preferably formed from polypropylene. The length of each wall forming the shape of a cell 18, when viewed in plan, is at least 8mm. This ensures that each cell is of an appropriate volume, for reasons which will be explained below.

The support layer 14 is intended to be laid on top of an aggregate base layer 12. The base layer 12 can be formed from crushed rock and sand which is transported to the site of the new playing surface. In such an instance, excavations are first undertaken to clear the area and form a pit into which the crushed rock and sand can be laid. The crushed rock and sand are then compacted in a conventional way in order to obtain a substantially level surface ready for the installation of the support layer 14.

Once the support layer 14 has been installed the artificial turf layer 16 is laid on the upper surface of the support layer 14. The artificial turf layer 16 is formed from a conventional artificial turf material.

Sometimes, the new playing surface is to be placed upon an existing aggregate. An example of this would be where the new artificial surface is to replace an old playing surface formed from red ash, often referred to as "blaze". Historically, it was very common in certain regions for playing surfaces such as football pitches to be formed from this red ash. In such cases, the aggregate layer 12 can be formed by levelling and compacting the aggregate which forms the existing surface. Once this has been done, the support layer 14 and artificial turf layer 16 may be installed as described above.

One of the key advantages of the present invention is its ability to retain water, thereby reducing the amount of drainage infrastructure required to drain water away from the playing surface. Each of the cells can store drained water such that the water from the playing surface does not pass straight through the support layer, as it does with known combined support/padding layers. Tests have been carried out using a 3m² support layer having a thickness of approximately 28mm, and it was shown that this support layer could hold over 26 litres of water per square metre. With a support layer covering a 7000m² sports pitch, this would mean that over 186000 litres of water can be retained in a support layer of the same thickness. A comparison test carried out using a known composite support layer formed from bound polypropylene beads showed that the known layer could only store approximately 8 litres of water per square metre.

With the use of the cellular support layer the present invention can drain the artificial turf layer as quickly as existing playing surfaces, but can also store a large volume of drained water and allow the water to drain away naturally without swamping the existing drainage system. In certain circumstances, use of the present invention can also lead to a reduction in the number of drainage pipes required, or even remove the need for drainage pipes altogether. Furthermore, if the groundwater level rises from below, the support layer can hold a far larger volume of the water than the support layers of existing artificial playing surfaces before the water seeps through the top artificial turf layer. The addition of a non- woven sheet on one or both faces of the support layer can further slow the ingress or egress of water from the support layer. By increasing the thickness of the support layer, even greater volumes of water can be held therein. Conventionally, the aggregate base layer was relied upon to slow the drainage of water. With the present invention, the water storage performance of the support layer means that the thickness of the base layer can be reduced as it does not need to retain any water. This has benefits in terms of both time and cost of constructing a new playing field.

As well as advantages in drainage, a support layer of honeycombed plastics panels is of a resilience that will provide enough support to maintain the speed of the playing surface compared to previous artificial surfaces, but is also compressible under loadings above a predetermined level. This ensures that higher impacts, such as a player's head coming into contact with the playing surface, are sufficiently cushioned. This resilience also allows the support layer a degree of flexibility which ensures that in the event that the base layer is not totally flat the support layer will follow the contours of the base and not leave gaps between the base and support layer. Such gaps could lead to deformations in the top artificial turf layer if allowed to remain.

The cellular arrangement of the support layer also ensures that loads are spread across the support layer and the base below. This ensures that the base does not become so compacted that it becomes impermeable to water, and also ensures that the base remains flat. Levelling out of the base once the playing surface is installed is not possible. The cellular arrangement of the panels also ensures that the support layer is relatively lightweight. This gives the added benefit that the thickness of the base layer can be reduced. Hence, less excavation is necessary and a reduced amount of base aggregate is required. This is a particular benefit where the present invention is to replace an existing red ash playing surface, as the red ash can be used for the base without the need for any additional base aggregate.

As the present invention only comprises two layers, it speeds up the installation of a new sports pitch. In addition, the support layer is formed from relatively large panels (e.g. 2500mm x 1200mm) which allow the support layer to be laid much quicker than previous proposals.

The present invention may be used for any type of artificial playing surface. Examples include football and field hockey pitches, cricket pitches and golf tee areas.

Whilst the panels making up the support layer of the present invention are preferably made from polypropylene, it should be understood that alternative plastics materials having the same resilience may also be used. The panels can also be made of any thickness from 5mm upwards, depending on the desired volume of water which can be retained in the cells. However, it has been found that a thickness in the range 20-40mm will give the optimum level of fluid storage volume, resilience and weight. Other suitable materials may also be used if desired. For example, the panels could alternatively be formed from rubber having the desired characteristics.

Whilst the preferred embodiment of the present invention describes panels which have a honeycomb structure in which the cells of the panel are substantially hexagonal, it should be understood that the invention is not limited to this arrangement. Instead, the panels may have an alternative cellular structure in which cells or cavities can hold the desired volumes of water. For example, the cells may be substantially in the shape of cubes or cuboids.

The invention is also not limited to an arrangement in which the panels have non-woven fibrous sheets covering each of the upper and lower faces of the panels. The sheet may cover only one of the upper and lower faces, or else the sheet may not be present at all. Where the sheet is present, the invention is not limited to use of a non-woven sheet, as other materials may be used instead. Furthermore, the sheet may be described above as preferably being thermowelded to the face(s) of the panel, but it should be recognised that alternative attachment methods may be used. An example of one such alternative attachment method is bonding of the sheet to the panel face(s).

The cells of each panel preferably extend across the entire depth of the panel, thereby opening on each of the upper and lower faces of the panel. However, the cells may alternatively only extend part way through the panel, from either the upper or lower face. In such an instance suitable apertures or passages are provided in the panel to allow water to pass from the closed end of each cell out of the panel. Each cell wall is preferably at least 8mm long, but the length of the walls can be varied depending on the volume of water likely to drain or pass through the panel. The dimensions, and hence volume, of each cell can be determined at the planning stage, with suitable consideration being taken of average rainfall and drainage in the area in which the playing surface is to be installed.

The panels may be laid adjoining one another so as to form a support layer having a larger surface area. In this case, the playing surface may include mechanical fixing means to fix the adjoining panels to one another. A non-limiting example of such fixing means may be resilient clips or clamps.

These and other modifications and improvements may be incorporated without departing from the scope of the invention.

Claims

CLAIMS:

1. An artificial playing surface comprising: a support layer comprising one or more panels, wherein each panel includes a plurality of cells; and an artificial turf layer lying upon an upper surface of the support layer.

2. The playing surface of Claim 1 , wherein each panel is a honeycomb panel in which each cell is substantially hexagonal.

3. The playing surface of either preceding claim, wherein each panel has upper and lower faces and at least one of the faces is covered with a non-woven fibrous sheet.

4. The playing surface of Claim 3, wherein both the upper and lower faces of each panel are covered by a non-woven fibrous sheet.

5. The playing surface of either Claim 3 or Claim 4, wherein the sheet is non-woven polyester.

6. The playing surface of any of Claims 3 to 5, wherein the sheet is thermowelded to the upper and/or lower faces.

7. The playing surface of any preceding claim, wherein each panel is formed from a plastics material

8. The playing surface of Claim 7, wherein the plastics material is polypropylene.

9. The playing surface of any preceding claim, wherein each cell extends across the depth of the panel.

10. The playing surface of any preceding claim, wherein each cell is defined by a plurality of cell walls, each cell wall being at least 8mm long.

11. The playing surface of any preceding claim, wherein the support layer comprises a plurality of adjoining panels and the playing surface further comprises mechanical fixing means for securing the panels to one another.

12. A support panel adapted to support a layer of artificial turf and form an artificial playing surface according to any preceding claim.

13. A method of installing an artificial playing surface, comprising: forming an aggregate base layer; laying one or more panels upon the base layer to form a support layer, each panel including a plurality of cells; and laying an artificial turf layer upon the support layer.

14. The method of Claim 13, wherein the forming of the base layer comprises levelling and compacting an existing aggregate layer.

15. The method of Claim 14, wherein the existing aggregate layer comprises red ash.

16. The method of Claim 13, wherein the forming of the base layer comprises excavating a pit and laying a mixture of crushed rock and sand therein.

17. The method of Claim 16, wherein the forming of the base layer further comprises the steps of levelling and compacting the crushed rock and sand within the pit.

18. The method of any of Claims 13 to 17, wherein the support layer comprises a plurality of adjoining panels and the method further comprises securing the panels to one another using mechanical fixing means.

19. The method of any of Claims 13 to 18, wherein each panel is a honeycomb panel in which each cell is substantially hexagonal.

20. The method of any of Claims 13 to 19, wherein each panel has upper and lower faces and at least one of the faces is covered with a non- woven fibrous sheet.

21. The method of Claim 20, wherein both the upper and lower faces of each panel are covered by a non-woven fibrous sheet.

22. The method of either Claim 20 or Claim 21 , wherein the sheet is non-woven polyester.

23. The method of any of Claims 20 to 22, wherein the sheet is thermowelded to the face(s).

24. The method of any of Claims 13 to 23, wherein each panel is formed from a plastics material.

25. The method of Claim 24, wherein the plastics material is polypropylene.

26. The method of any of Claims 13 to 25, wherein each cell extends across the depth of the panel.

27. The method of any of Claims 13 to 26, wherein each cell is defined by a plurality of cell walls, each cell wall being at least 8mm long.