Playing Surfaces Sports

This invention relates to a method of constructing a playing surface for sports and the like.

Because of the problems of maintaining in good condition traditional grass or turf playing surfaces for such sports as soccer, cricket and tennis, especially when the surfaces are subject to frequent use during periods of excessively high or low rainfall, synthetic turfs, typically in the form of a resilient carpet formed from plastics materials such as polypropylene, have been developed. Synthetic turfs have heretofore been laid in the manner of a carpet, using a resilient underlay placed on a prepared surface such as concrete with suitable drainage. A problem experienced with such playing surfaces is that the playing characteristics of the surfaces are very different from conventional turf, the ball in ball games bouncing faster and rolling differently.

According to the present invention there is provided a method of constructing a playing surface for sports and the like, characterised by the steps of:

(A) laying on a drained or water-permeable surface at least one envelope formed of a flexible water-permeable material and containing an unbonded base material comprising sand; and

(B) placing on the envelope or envelopes a sheet of a resilient material.

The sheet of resilient material may be formed from rubber particles, such as comminuted used motor vehicle tyres, bonded together with a polymeric material. The thickness of the sheet will depend on the game for which the surface is intended and the construction of the underlying envelopes and surface. A typical thickness would be 6 mm.

Alternatively, the sheet of resilient material may comprise dense expanded polyethylene. A combination of the two types of resilient sheet material may be used, with either the bonded particulate rubber material or the polyethylene material lowermost according to the characteristics of the surface required. A synthetic playing surface material, such as a synthetic turf or a carpet material, may be placed on the resilient sheet or sheets, to simulate more closely a turf playing surface. In one embodiment of the invention a synthetic playing surface material itself constitutes the resilients sheet material laid direct on the envelope or envelopes.

Preferably, the thickness of the base material in the envelope or envelopes is in the range of 12 mm to 75 mm. The thickness chosen will depend upon the characteristics desired. Preferably, especially for surfaces other than for cricket a plurality of envelopes is used, the envelopes fitting together to form a continuous layer, the sheet of resilient material being placed on the continuous layer so formed. The sizes of the envelopes preferably vary from 4 m wide.times.20 m long in areas of less intense wear to 2 m wide.times.7 m long in areas of high intensity wear. The or each envelope may by sub-divided by the use of resiliently-compressible strips, e.g. of expanded plastics material, laid on to the lower layer of envelope material.

Suitable ranges of compositions for the base material are indicated in the following table

The characteristics of the base material may alternatively be modified by adding to the sand materials such as plastics foam chips or particles. These envelopes may be formed of pairs of sheets of permeable fabric, pinned or glued or otherwise joined together at the edges. Different types of fabric may be used to form the upper and lower layers of the envelope.

The method of the invention produces a playing surface which avoids the maintenance requirements of conventional turf but which gives playing characteristics much closer to those achieved by conventional turf and which change with weather conditions in a similar manner to conventional turfs, but without the risk of degradation of the surface into mud, or ruts in very dry or very cold weather.

Further features, details, and advantages of the invention will be apparent from the following description of alternative embodiments of the invention, with reference to the drawings, in which:

FIG. 1 is a sectional view of a playing surface suitable for winter games; and

FIGS. 2 and 3 are sectional views of playing surfaces similar to that shown in FIG. 1, but modified to produce characteristics suitable for cricket or tennis.

Referring first to FIG. 1, the ground 1 upon which the playing surface 2 is to be laid is first prepared, if not already adequately drained, by the installation of drainage channels or 3 filled with suitable permeable material and then levelled.

Envelopes 4 are prepared from sheets of a permeable glass fibre fabric, filled with the sand base material 5, and folded and pinned at the edges. At joins 6 between adjacent envelopes, the edge 7 of the first envelope 4a is left free of sand and is pinned or nailed to the ground using corrosion-resistant nails 8 of suitable length. The second envelope 4b is then positioned over the thin edge portion 7. The composition of the sand base materials is chosen from the range of compositions set out hereinbefore in the Table, for winter games pitches. An underlay 9, comprising a mat of polymer bonded rubber particles, is then laid on top of the envelopes and suitably secured, e.g. by nails or pins at the edges thereof, and the synthetic turf 10 can then be laid on the underlay 9 in the conventional manner.

The surfaces illustrated in FIGS. 2 and 3 are modified to suit summer games such as cricket or tennis. The sand base material 5 is chosen from a range of compositions in the second part of the Table hereinbefore. In the surface illustrated in FIG. 2, the synthetic turf is replaced by a layer 20 of a dense polyethylene foam with a thickness of about 5 mm and a density of 175 kg/m.sup.3. This layer 20 serves to reduce the degree of bounce of a ball striking the surface, and is in itself known for such applications. In FIG. 3, the surface illustrated is identical to that of FIG. 2, but has a layer of synthetic turf placed on the foam layer 20.