Playing Surface

Abstract

A playing surface comprising a supportive base layer, an intermediate layer such as a foam layer, and a surface layer, wherein the base layer is configured to provide the playing surface with a first predetermined amount of stability and the intermediate layer, e.g. foam layer, is configured to provide the playing surface with an additional, second predetermined amount of stability, the intermediate layer, e.g. foam layer, being further configured to conform to a required performance standard. And a method of constructing a playing surface.

Claims

1. A playing surface comprising a base layer, an intermediate layer, and a surface layer, wherein the base layer is configured to provide the playing surface with a first predetermined amount of stability and the intermediate layer is configured to provide the playing surface with an additional, second predetermined amount of stability, the intermediate layer being further configured to conform to a required performance standard.

2. The playing surface of claim 1, wherein the intermediate layer comprises one or more energy dissipating formations, optionally wherein the energy dissipating formations are configured to dissipate energy of an impact on the playing surface through deformation.

3. (canceled)

4. The playing surface of claim 2, wherein the intermediate layer comprises a plurality of downwardly extending energy dissipating projections, optionally wherein at least two of the plurality of projections have a height of at least approximately 10 mm, and optionally, the majority or all of the plurality of projections have a height of at least approximately 10 mm.

5. The playing surface of claim 1, wherein the intermediate layer is formed of a plurality of tiles, optionally wherein the plurality of tiles comprise a plurality of interlockable tiles, each tile having formations for cooperating with formations on the other tiles for interlocking the tiles together.

6. (canceled)

7. The playing surface of claim 1, wherein the intermediate layer comprises a top surface that contacts the surface layer, the top surface of the foam layer being configured to provide high frictional resistance to the relative movement between the top surface and surface layer, optionally wherein the top surface of the intermediate layer is rough, uneven, or irregular.

8. (canceled)

9. The playing surface of claim 1, wherein the surface layer is or comprises a layer of artificial turf.

10. The playing surface of claim 1, wherein the intermediate layer comprises or consists essentially of a foam layer, optionally wherein the foam layer is formed of or comprises expanded polypropylene, and further optionally wherein the density of the foam layer is at least approximately 30 grams per litre, and more optionally, the density of the foam layer is approximately 30 to 60 grams per litre.

11. (canceled)

12. (canceled)

13. The playing surface of claim 1, wherein the intermediate layer has a thickness of approximately 40 mm to 65 mm.

14. (canceled)

15. The playing surface of claim 1, wherein the supportive base layer comprises clean stone or dusty stones or a combination of both.

16. The playing surface of claim 1, wherein the base layer is approximately 150 mm thick.

17. The playing surface of claim 1, wherein the intermediate layer further comprises one or more holes extending from the top surface to a bottom surface of the intermediate layer.

18. The playing surface of claim 1, further comprising an impervious layer between the intermediate layer and the base layer, optionally wherein the impervious layer is formed of or comprises an impermeable membrane, optionally wherein the impervious layer is configured to direct liquid to a preferred edge, edges or portion(s) thereof of the intermediate layer, optionally further comprising a drainage means or drainage system configured to collect fluid from the surface of the impervious layer, optionally wherein the playing surface is configured such that the playing surface has a horizontal drainage flow capacity of 0.4 litres per metre per second or more.

19-22. (canceled)

23. A method of constructing a playing surface comprising the steps of: partially filling a vacant space to form a base layer; placing an intermediate layer above the base layer; and placing a surface layer above the foam layer; wherein the base layer is configured to provide the playing surface with a first predetermined amount of stability and the intermediate layer is configured to provide the playing surface with a second predetermined amount of stability, and the intermediate layer being further configured to conform to a required performance standard.

24. The method of claim 23 further comprising the step of excavating the layer of soil to form the vacant space.

25. The method of claim 23, wherein the vacant space has a depth of no more than 300 mm.

26. The method of claim 23, wherein the foam layer comprises one or more energy dissipating formations, optionally wherein the energy dissipating formations are configured to dissipate energy of an impact on the playing surface through deformation.

27. The method of claim 23, wherein the intermediate layer comprises or consists essentially of a foam layer, optionally wherein placing the intermediate layer comprises placing a plurality of foam tiles on top of the base layer, each tile comprising one or more energy dissipating formations, optionally wherein the energy dissipating formations are configured to dissipate energy of an impact on the playing surface through deformation.

28. (canceled)

29. (canceled)

30. The method of claim 23, wherein partially filling the vacant space comprises partially filling the vacant space with stones, wherein the stones may be clean stones or dusty stones or a combination of both.

31. The method of claim 23, further comprising the step of placing an impervious layer between the base layer and the intermediate layer.

32. The method of claim 23, further comprising the step of providing a drainage means or drainage system to collect fluid from the surface of the impervious layer.

Description

DETAILED DESCRIPTION

[0036] The invention is described in further detail below by way of example and with reference to the accompanying drawings, in which:

[0037] FIG. 1 is a schematic cross sectional diagram of an embodiment of a playing surface;

[0038] FIG. 2 is a schematic cross sectional diagram of a foam layer;

[0039] FIG. 3 is a schematic diagram of a tile of a foam layer; and

[0040] FIG. 4 is a schematic cross sectional diagram of an alternative embodiment of a playing surface.

[0041] FIG. 1 illustrates schematically a cross section of an embodiment of a playing surface 1, such as an artificial sports pitch, according to the invention. The term playing surface is widely used in the art, and is understood to mean the layer or layers, either natural or artificial, that provide the uppermost portion of the playing pitch, court or suchlike. The playing surface of the present invention comprises a supportive base layer 2, an intermediate layer 3 and a surface layer 4.

[0042] The supportive base layer 2 is typically composed of stones. To build a playing surface according to conventional systems, a large volume of ground must first be excavated, producing a large amount of soil that must be removed from the site and disposed of. This process is both time-consuming and environmentally damaging.

[0043] A large amount of stones must be brought to the site to fill the majority of the depth of the excavated hole. A thick stone layer is necessary to provide sufficient support and stability to the surface layer above, in particular a macadam layer and the laying of it with heavy, specialist machinery. Providing this large amount of stone is again time-consuming and environmentally damaging.

[0044] It is an aim of this invention to reduce the thickness of the supportive base layer required to provide sufficient support to the above layers. This will reduce the number of stones and amount of excavation needed, and make building the playing surface more environmentally friendly, as well as reducing the time required for installation of the pitch.

[0045] This aim is achieved by providing an intermediate layer such as a foam layer 3 that is configured to provide both stability and performance regulation to the surface layer 4 above. In this way, the thickness of the supportive base layer 2 may be significantly reduced from approximately 300-350 mm, as is typical in conventional playing surfaces, e.g. to about 150 mm thick.

[0046] Performance regulation is crucial to replicating the feel of a natural grass pitch, and to providing a playing surface that can absorb the impact of falls and minimise the risk of injury to players on playing surface. In conventional systems, this has been provided by a regulation layer such as foam or shock pads. In those systems, the regulation layer did not provide a supportive function, and so required a large stone supportive layer.

[0047] Advantageously, by using a suitable foam layer, the foam layer can provide both the necessary performance regulation and support to the surface layer above and the stability of the overall construction. In this way, the thickness of the supportive base layer may be greatly reduced, e.g. to around half or even a third, of the values typical in conventional playing surfaces.

[0048] In a preferred embodiment shown in FIG. 2, the foam layer 3 comprises a top surface 5 and a bottom surface 6. The top surface 5 may have a roughened texture to provide high frictional resistance to relative motion between the top surface 5 and the surface layer 4. A high resistance may prevent movement of the surface layer 4 during games played upon the surface layer 4.

[0049] The bottom surface 6 comprises a plurality of energy dissipating projections 7 extending downwards away from the top layer. The plurality of projections 7 are arranged to dissipate energy of an impact through deformation. The projections 7 have a height that is less than the total thickness of the foam layer 3. The projections 7 are shaped (tapered) such that they are narrowest at their bottom-most part. Valleys 8 are formed between the projections 7.

[0050] In the illustrated embodiment, the projections 7 are dome shaped, however it will be understood that other shapes may be used for the projections 7. In particular, the shape of the projections 7 may be selected to provide the most suitable performance regulation to the surface layer 4 for the sport or game that is intended to be played upon the surface layer 4.

[0051] In this preferred embodiment, the dome shaped projections 7 are arranged in a pseudo-hexagonal packing arrangement with each projection 7 being close to, but spaced from, adjacent projections 7. The spaces between the projections form part of the valleys 8.

[0052] In this embodiment, the foam layer 3 is formed of expanded polypropylene with a density of approximately 40 grams per litre. In other embodiments, the density of the foam layer 3 may be greater than about 30 grams per litre, or preferably, approximately 30 to 50 grams per litre, or approximately 30 to 60 grams per litre. Lower densities could be used, but generally cannot provide the performance regulation and stability required of the foam layer 3.

[0053] Alternatively, foam layer 3 may be formed of other suitable materials, such as polyurethane, or expanded polyethylene.

[0054] The foam layer 3 may have a thickness, defined from the top surface 5 to the bottom-most part of the bottom surface 6, of around 40 to 65 mm. In the illustrated embodiment, the foam layer 3 has a thickness of approximately 55 mm. The plurality of projections 7 have a height h of approximately 15 mm, defined from the vertical position where the projection 6 is narrowest to the vertical position where the projection 6 is widest. In other embodiments, at least two of the plurality of projections may have a height of at least approximately 10 mm, and preferably the majority of the plurality of projections 7 have a height of at least approximately 10 mm. In a preferred embodiment, the majority of the plurality of projections have a height of approximately 15 mm.

[0055] In some embodiments, the foam layer 3 illustrated in FIG. 2 may comprise a plurality of foam tiles, wherein each tile comprises a top surface 5 and a plurality of downwardly extending energy dissipating projections 7, the plurality of projections 7 being arranged to dissipate energy of an impact through deformation. Providing the foam layer 3 as a plurality of tiles may facilitate transportation and construction of the playing surface 1. The foam tiles may have any shape. For example, the foam tiles may be substantially rectangular in shape, e.g. with lengths of at least 1100 mm and/or to up to 1700 mm, and widths of at least 800 mm and/or up to 1300 mm. In a preferred embodiment, the dimensions of the foam tile may be approximately 1200 mm900 mm. In an alternative embodiment, the dimensions of the foam tile may be approximately 1600 mm1200 mm.

[0056] FIG. 3 schematically illustrates a preferred embodiment of a foam tile 9. In this embodiment, tile 9 further comprises recesses 10 and protrusions 11. These formations are configured to cooperate with corresponding formations on adjacent tiles 9 in order to interlock adjacent tiles 9. Interlocking the tiles 9 may make foam layer 3 more stable.

[0057] In this embodiment, the tile 9 further comprises one or more holes 12 extending from the top surface 5 to the bottom surface 6 of the tile 9. Typically, each hole 12 may extend from the top surface 5 to a part of the bottom surface 6 that is between projections 7. The holes 12 allow water to drain from the surface layer 4 through to the bottom surface 6 of the foam layer 3. Adequate drainage is necessary to keep the surface layer 4 in a good condition. Holes 12 may be present in any other embodiment of the playing surface 1. FIG. 3 shows six holes provided evenly across the extent of the tile 9, but it will be appreciated that any number (e.g. 1, 2, 3, 4, 5, or more) may be provided. The hole(s) 12 may be of any size and shape, in any location, and arranged in any pattern as suits the requirement of the playing surface 1.

[0058] The holes 12 may have a diameter of up to or at least 5 mm, up to or at least 10 mm or up to or at least 20 mm. Typically, the holes may have a diameter of approximately 5 mm.

[0059] The tile may comprise up to or at least 10, up to or at least 20, up to or at least 30, up to or at least 40, and/or up to or at least 50 holes extending from the top surface to the bottom surface of the tile.

[0060] In an example embodiment, the tile may comprise 30 holes extending from the top surface to the bottom surface of the tile, the holes being arranged in a five-by-six array.

[0061] If the playing surface is to be used in an enclosed environment, such as a covered stadium, drainage may not be required. For outside playing surfaces, particularly in wet climates, adequate drainage is essential to maintain the quality of the surface.

[0062] In some embodiments, one or more additional foam layers 3 may be stacked on top of foam layer 3, to provide additional support. Tiles 9 may be stacked vertically stacked to produce such a stacking of foam layers 3.

[0063] The surface layer 4 of a playing surface 1 may be any suitable surface for playing sports or games on, and may be adapted for the playing of a particular sport. For sports traditionally played on natural grass pitches, for example, surface layer 4 may comprise an artificial turf.

[0064] Conventional artificial pitches may suffer from frost heave. Frost heave may cause a pitch to swell upwards due to growing ice trapped under the surface in freezing conditions. To minimise this effect, the depth of the supportive layer is generally increased, increasing cost, environmental impact and installation times.

[0065] In contrast, in the much thinner supportive base layer 2 of embodiments of the present invention, frost heave is unlikely. The foam layer 3 may provide good thermal properties to minimise the effects of frost. For example, it has been found that the foam tiles of the present invention have equivalent thermal properties to a 1.7 m-deep layer of stone or aggregate.

[0066] The present invention also allows the use of stone with a finer content than in previous dynamic systems, and a thinner depth of stone than engineered systems. Finer stones provide even more stability, and so may allow the thickness of the supportive base layer 2 to be further reduced.

[0067] FIG. 4 schematically illustrates an alternative embodiment of a playing surface 13, configured to provide adequate drainage. Playing surface 13 comprises a supportive base layer 14, a foam layer 15 and a surface layer 16, as in the embodiment illustrated in FIG. 1. Any of the different embodiments of the supportive base layer 2, foam layer 3 and surface layer 4 described above may be incorporated, alone or in combination, into playing surface 13.

[0068] Playing surface 13 further comprises an impervious layer 17 between the foam layer 15 and the supportive base layer 14. Impervious layer 17 may collect water draining downwards from the surface layer 16, and prevent the water from entering the supportive base layer 14, as will be discussed in more detail below.

[0069] The impervious layer 17 may be an impervious membrane. The impervious layer may comprise a polymeric material, e.g. polyethylene or polypropylene. For instance, the impervious layer may comprise or be made of polyethylene or coated polypropylene.

[0070] In an embodiment, foam layer 15 is comprised of the tiles 9 discussed above, each tile having a plurality of downwardly extending energy dissipating projections 7, and drainage holes 12. Water from the surface layer 16 may drain downwards through the holes 12 until it reaches impervious layer 17. The valleys 8 between the projections 7 form channels so that water may flow between the impervious layer 17 and the foam layer 15.

[0071] In conventional playing surfaces, drainage is provided by installing drainage pipes or channels under the supportive base layer of the playing surface to carry water to an appropriate outlet. Some water is also lost to the ground below the playing surfaces. This method requires additional deep excavation to house the drainage pipes.

[0072] By using the embodiment of FIG. 4, drainage channels do not need to be excavated under the playing surface, reducing the installation time.

[0073] The impervious layer 17 may be configured to direct water to a preferred edge or edges or portion(s) thereof of the foam layer 15 so that uncertainty as to where water will drain from is removed. For example, the supportive base layer 14 may be built with a slight incline across at least a portion of its surface, so that the impervious layer 17 is slightly inclined. The slight incline across the surface of the supportive base layer may be at least, up to or approximately 1%, at least, up to or approximately 3%, and/or at least, up to or approximately 5%. Water on the impervious layer 17 may thus be directed to the lowest part(s) of the impervious layer 17. For example, the impervious layer 17 may be inclined by at least, up to or approximately 1%, at least, up to or approximately 3%, and/or at least, up to or approximately 5%.

[0074] A drainage system 18 may be installed at the edge of the playing surface 13. Drainage system 18 may comprise a pipe or channel that can collect water running off the impervious layer 17, and transport it away from the playing surface 13. Draining water in this way is more efficient than conventional drainage systems, and may allow the collected water to be recycled.

[0075] Tests carried out by the applicant have shown that a pitch according to the present invention may have exceptional horizontal drainage characteristics. The tests were carried out on a pitch according to the invention, in which the intermediate layer comprised a plurality of interlocking tiles made of expanded polypropylene. Each tile comprised a plurality of downwardly extending, hemispherical projections. The pitch further comprised an impervious layer between the intermediate layer and the supportive base layer. In use, water can flow horizontally (i.e. drain from the pitch) in the spaces between the downwardly extending projections and on top of the impervious layer.

[0076] Some results from the applicant's horizontal drainage testing are shown in Table 1 below.

TABLE-US-00001 TABLE 1 Flow capacity l/(m*s) Sample 1 Sample 2 Sample 3 Mean value Gradient l/(m*s) l/(m*s) l/(m*s) l/(m*s) 0.01 0.553 0.551 0.556 0.55 0.03 0.845 0.853 0.849 0.85 0.05 1.023 1.024 1.024 1.02

[0077] Referring to the data in Table 1, for an incline of the supportive base layer and the impervious layer of 1% (a gradient of 0.01), a mean horizontal drainage (flow capacity) of 0.55 litres per metre per second (l/(m*s) was achieved. For an incline of 3% (a gradient of 0.03), the mean horizontal drainage increased to 0.85 l/(m*s), while for an incline of 5% (a gradient of 0.05), the mean horizontal drainage was 1.02 l/(m*s).

[0078] By way of comparison, in similar tests, a pitch comprising a rubber performance layer arranged on a macadam base typically achieves a horizontal drainage (flow capacity) of around 0.09 l/(m*s), i.e. much lower than the horizontal drainage characteristics that can be achieved with a pitch according to the present invention. In order to boost the horizontal drainage characteristics of a pitch comprising a rubber performance layer arranged on a macadam base, additional drainage channels may be excavated, thereby increasing complexity and the time required to build the pitch.

[0079] Advantageously, however, due to its exceptional horizontal drainage characteristics, a pitch according to the invention may be built without needing to excavate such drainage channels.

[0080] In order to construct the playing surface 1 described above, first a layer of soil may be excavated to form a vacant space, followed by partially filling the vacant space to form a supportive base layer 2. A foam layer 3 is placed above the supportive base layer 2, and a surface layer 4 placed above the foam layer 3. The foam layer 3 is configured to provide a predetermined amount of stability and performance regulation to the surface layer 4.

[0081] Excavating the layer may be achieved using any suitable tool or machine. The excavated space must have the same or slightly larger areal dimensions as the playing surface 1, and its depth must be substantially the same or at least a substantial fraction of the total height of the playing surface 1.

[0082] The vacant space may be partially filled with stones or crushed stones to form the supportive base layer 2. The stones may be clean stones or dusty or dirty stones or a combination of both.

[0083] A foam layer 3 as described above is placed on top of the supportive base layer 2. In an embodiment, placing the foam layer 3 on to the supportive base layer 3 comprises placing a plurality of interlocking foam tiles 9 onto the supportive base layer 2 to form the foam layer 3.

[0084] In some embodiments of the method, an impervious layer 17 is placed on top of the supportive base layer 2 before the foam layer 3 is located. In these embodiments, placing the foam layer 3 comprises placing a foam layer 3 on top of the impervious layer 17, which is in turn on top of the supportive base layer 2.

[0085] The impervious layer 17 may be provided as a roll of material, and placing the impervious layer 17 may comprise unrolling the material across the supportive base layer 2.

[0086] Other embodiments are intentionally within the scope of the invention as defined by the appended claims.