NZ261574A

NZ261574A - Grass surface, grass grown in layer of sand and randomly oriented synthetic fibres with length in range of 5-75mm

Info

Publication number: NZ261574A
Application number: NZ26157494A
Authority: NZ
Inventors: Michael Harry Wilson Cannon
Original assignee: Fibresand Ltd
Priority date: 1993-02-13
Filing date: 1994-02-03
Publication date: 1997-03-24
Also published as: GB2274997A; CN1117748A; DE69404636T2; GB2274997B; EP0616078A1; AU6038494A; EP0690941B1; GB9302906D0; DK0690941T3; AU678433B2; WO1994018394A1; CA2155551A1; EP0690941A1; DE69404636D1

Description

New Zealand Paient Spedficaiion for Paient Number £61 574 New Zealand No. 261574 International No. PCT/EP94/00317 Priority Date(s): Compete Specification Filed: CUuu: (6)...X.O.lC..l^y!.QQ^....AO./.^37/oc .

P.O. Journal f4o: IHIMt..:.

NO DRAWINGS NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION Title of Invention: Improved surfaces fcr sporting and other activities Name, address and nationality of applicant(s) as in international application form: FIBRESAND LTD, of Sandhurst Avenue, Mansfield, Nottinghamshire NG18 4BE, United Kingdom ^ okA 1 IMPROVED SURFACES FOR SPORTING AND OTHER ACTIVITIES FIELD OF THE INVENTION The present invention relates to improved surfaces for sporting and other activities, and more particularly to surfaces suitable for equestrian usage, for ball games, such as football and golf, and other leisure activities.

BACKGROUND OF THE INVENTION The natural surface for most equestrian events, particularly horse jumping, is grass. This is acceptable for large areas such as race courses where the usage is low and the 10 grass therefore has time to recover between race meetings. Where the surface is used more extensively, for example, in training areas, grass, particularly in the autumn and winter period, becomes worn and muddy patches appear. These patches form dusty hard surfaces in dry conditions, and this may lead 15 to an unacceptable incidence of leg injuries.

As an alternative to grass a number of artificial surfaces have been used. A first known surface comprises natural wood fibre and this when new provides a good surface. It is however a natural material and therefore deteriorates with age. Thus 20 it has to be replaced and since it is fairly expensive the replacement cost is high. A second Known surface comprises finely chopped PVC often from used electrical cable insulation material. This produces a good surface but if laid deeply the surface is rather loose and the cost of the material is very 25 high. A third known surface comprises ashes from power CONFIRMATION COPY WO 94/18394 PCT/EP94/00317 ► stations. The ashes provide a surface which drains readily when newly laid in wet weather but in dry conditions the surface produces dust and becomes compacted becoming hard especially after prolonged use. An alternative surface is 5 silica sand which provides a good surface in wet weather conditions but in dry weather conditions the sand provides an extremely difficult surface for both jumping and landing particularly for an equestrian practise ring. The principal problem of silica sand is that it lacks cohesion therefore 10 providing a surface which is described as riding too deep and loose.

The natural surface for roost ball games is also grass. The damage to the turf and soil structure which is caused by normal usage is intensive and the scale of damage can exceed 15 the rate of such recovery. This is particularly pronounced in areas such as goal mouths and centre circles of football pitches and on golf tees where the turf can be totally destroyed and the soil severely compacted. In wet weather this means mud; in dry weather the surface is hard and bumpy. 20 As an alternative to grass a number of artificial surfaces have been used. A first known surface, commonly known as hard porous, comprises water bound grit/sand/clay mixtures of differing proportions, normally laid over a drainage layer of coarser material. This surface provides inadequate cushioning 25 and is too abrasive. The surface material also becomes destructured and therefore loses permeability. In dry weather dust is a problem.

WO 94/18394 PCT/EP94/00317 1 3 A second known surface comprises a synthetic material designed to imitate real turf. This may be laid on soil or on a drainage layer of sand or other material. This synthetic turf may or may not be infilled by a top dressing of sand.

Such a surface is expensive to install and has insufficient resilience for falling players. Maintenance and repairs are difficult and costly.

A third known surface comprises a layer of fibres which are joined together in a loose pattern, laid in a bed of sand 10 which in turn may be laid on a drainage layer of other material. Maintenance and repairs are difficult and costly. Play characteristics are poor.

A fourth known surface comprises a layer of sand or granular material bound by bitumastic or similar, material. 15 Such a surface has insufficient resilience, is too abrasive and is difficult and costly to repair and maintain.

It can be seen from the above that where the wear on a playing surface is severe, the tendency has been to move away from grass to synthetic surfaces of various kinds. However, 20 for many reasons, both aesthetic and practical, it would still be preferable to employ a grass surface if its wearing properties could be improved.

In British patent No.2l84765B there is described and claimed an all weather surface for equestrian events which has 25 proved to be highly successful in practice. The surface comprises a layer of material, the material comprising a mixture of sand and elongate synthetic fibres, the fibres being randomly dispersed as separate individual fibres throughout the WO 94/18394 PCT/EP94/00317 4 sand, in which the fibres are in the range of 25 to 75 nun in length and are of uncrimped form. This is still, however, a wholly synthetic surface.

SUMMARY OF INVENTION We have now discovered an improved all weather grass surface in which the root zone is stabilised with synthetic fibres, whilst maintaining a structure with good drainage and aeration, and an improved sub-base for surfaces for sporting 10 and for other activities.

According to one aspect of the present invention there is provided an improved grass surface in which the grass is grown in a layer of material comprising sand, an organic growth supporting medium and elongate synthetic fibres, the fibres 15 being randomly dispersed as separate individual fibres in the material, and having a fibre length from 5mm to 75mm.

In another aspect the invention provides a method of forming an improved grass surface, which comprises sowing grass seed in, or applying turf to, a layer of material comprising 20 rand, an organic growth supporting medium and elongate synthetic fibres, the fibres being randomly dispersed as separate individual fibres in the material, and having a length from 5mm to 75mm.

In a further aspect, the invention provides a growing 25 material for a grass surface, which comprises sand, an organic growth supporting medium and elongate synthetic fibres, the fibres being randomly dispersed as separate individual fibres WO 94/18394 PCT/EP94/00317 1 5 in the growing material, and having a fibre length from 5mm to 75mm.

In a still further aspect the invention provides a sub-base for a surface for sporting and/or other activities which 5 comprises a layer of material comprising a mixture of sand, a particulate or fibrous organic material comprising vegetable matter and elongate synthetic fibres, the fibres being randomly dispersed as separate individual fibres in the mixture and having a fibre length of from 5mm to 75mm.

DETAILED DESCRIPTION OF THE INVENTION The components of the material of the present invention are sand, an organic medium which may be an organic growth supporting medium or a particulate or fibrous organic material 15 comprising vegetable matter and elongate synthetic fibres.

Sand, suitable for use in the present invention, may be silica sand, or a sand bonded with a water activated clay. Sands bonded with an organic liquid activated clay, which are sometimes used for equestrian surfaces, are in general not 20 suitable for use in the present invention.

Silica sand is a sand which is relatively clean, is clay free, and is a well graded sand produced by a wet classification method. Sand bonded with water activated clay is a sand in which the sand particles are coated with a water 25 activated clay which imparts a degree of cohesive strength to the sand, the extent of the cohesive strength being dependent on the relative amounts of clay and water.

WO 94/18394 PCT/EP94/00317 Preferably the sand particles have an average diameter in the range of from 100 to 1000 microns.

The organic growth supporting medium may be any suitable particulate or fibrous material which can be penetrated by 5 grass roots, but is preferably soil, peat, or a mixture thereof.

Where soil is used, this is preferably good quality top soil (screened and/or sterilised) from an approved source. Top soil provides a base source of nutrients for the grass and 10 provides moisture retention characteristics.

The peat is preferably from an approved source and provides an organic content which acts to retain moisture and provide a source of root promoting bacterial activity in the root zone.

The organic growth supporting medium is preferably supplemented with a soil conditioner such as a seaweed based soil conditioner, for example, Alginure soil improver, which contains an organic colloid capable of aggregating soil and intensifying microbial life as well as providing a supply of 2 0 trace elements.

Where the organic medium is a particulate or fibrous organic material comprising vegetable matter, it may also be, but need not necessarily be, growth supporting. The particulate or fibrous organic material can for example be 25 soil, humus, peat or other similar materials derived from the partial decomposition of vegetable matter.

The elongate synthetic fibres preferably comprise fibres of a synthetic polymeric material having good resistance to WO 94/18394 PCT/EP94/00317 7 environmental conditions. Fibres of polyolefins such as polyethylene, polypropylene, polybutene or co-polymers thereof are suitable, together with polyamides such as nylon, halogenated polymers such as PVC, and other similar materials.

The fibres can have a fibre length of from 5 to 75mm, preferably from 10 to 75mm, most preferably from 20 to 40mm. The average diameter of the fibres is preferably from 50 to 150 denier, for example about 65 denier.

The fibres are preferably polypropylene fibres commonly 10 referred to as staple fibre.

Preferably the layer of growing material or the sub-uase is from 25 to 150mm thick, most preferably from 50 to 150mm thick.

It is highly advisable to add to the layer of growing 15 material a fertiliser at least prior to seeding or planting and at regular intervals thereafter. An inorganic fertiliser comprising a balanced supply of nitrogen, phosphorus and potassium (N, P and K) may be added to the root zone, and for example a typical pre-seeding fertiliser (5, 7.5, 5) may be 20 added to the growing material at the mixing stage or sprayed or sprinkled onto the surface of the layer of growing material in situ. The fertiliser should be chosen to provide a balanced supply of the main nutrients required for healthy turf growth.

The ratio of the components of the material will depend 25 to some extent on the nature of the components chosen. Where silica sand is used, this preferably comprises from 50 to 95% by volume most preferably from 60 to 85% by volume of the total composition. Where sand bonded with water activated clay is WO 94/18394 PCT/EP94/00317 8 used, this preferably comprises from 50 to 95 percent by volume of the total composition.

For the organic growth supporting medium, where top soil is used, this preferably comprises from 5 to 50% by volume iaout 5 preferably from 6 to 20% by volume of the total growing material composition, and where peat is used this preferably comprises from 5 to 25% by volume most preferably from 5 to 15% by volume of the composition.

For the particulate or fibrous organic material component 10 of the sub-base, where top soil is used, this preferably comprises from 5 to 50% by volume most preferably from 5 to 20% by volume of the total material composition, and where peat is used this preferably comprises from 5 to 25% by volume most preferably from 5 to 15% by volume of the composition. 15 Where a seaweed based soil conditioner is used this is preferably applied in an amount of from 50 to lOOg/m2, preferably about 75g/m2.

The fertiliser is preferably added in an amount of from 10 to 50kg/20 tonnes of total composition by weight, for 20 example about 25kg/20 tonnes of total composition by weight, or applied to the layer in situ at a rate of from 50 to l00g/m2, preferably about 75g/2.

The percentage of synthetic fibres in the total material composition is preferably in the range of 0.1 to 0.9% by 25 weight, most preferably from 0.25 to 0.5% by weight, for example about 0.4% by weight. In general the percentage of fibres is at the higher end of the range when silica sand is WO 94/18394 PCT/EP94/00317 9 used, and the lower end of the range when sand bonded with water activated clay is used.

The fibres may be coloured to conform to the colour of the growing material and thereby be substantially invisible in use.

The components of the growing material may be mixed in any order, or simultaneously, to give a substantially homogeneous mixture. It is important to distribute the fibres evenly and randomly throughout the mixture, and it has been found in practice that it is preferable to pre-mix the sand and the 10 fibres together to obtain an even random dispersion.

In the preparation of an all weather grass surface according to the invention, turf and top soil are removed to the required depth and replaced with a layer of the growing material. A greater depth of turf and top soil may be removed 15 particularly if the drainage characteristics are poor and the lower layer may be replaced with a drainage base comprising clean crushed rock or gravel of appropriate size laid to an appropriate thickness in accordance with normal drainage engineering design rules.

The growing material is prepared by taking a quantity (usually several tonnes) of sand which is in a fairly moist condition and mixing into the sand a quantity of polypropylene fibres of the desired length. The sand is preferably selected to have an average particle size of from 100 to 1000 microns 25 with particles of rounded to sub-angular shape and is mixed with the fibres for example in a high intensity mixer of the contra rota Ling type which mixes the fibres homogeneously in a randomly orientated distribution throughout the sand.

WO 94/18394 PCT/EP94/00317 The random distribution of fibres stabilises the sand imparting resistance to particle movement under load from horses hooves etc, thus minimising spreading and hoof penetration such that a sure footing is obtained. The fibre 5 length is required to be long enough such that a "crosslinking" effect is produced thereby preventing the sand from moving under the pressure of the horses hooves, players feet, or other users such as wheeled vehicles or implements.

Thus the particle size of the sand and the diameter and 10 length of the fibres require to be carefully selected within the preferred ranges to suit the intended use.

Relatively straight fibres need to be used since crimped fibres are not readily mixed to produce a substantially "homogeneous" mixture. The length of the fibres is of 15 particular importance since this provides, in the homogenous fixture, the crosslinking which is necessary to prevent the mixture from spreading under the shock loading produced by horses hooves, players feet, or other users as aforesaid.

Following mixing of the sand and the fibres, this mixture 20 is further mixed with the organic growth supporting medium and any soil conditioner and/or fertiliser as appropriate. Following mixing the growth material is delivered to the prepared site and laid out to the required depth to give the desired surface characteristic. The characteristic of the 25 surface can be altered by the choice of sand particle size and the percentage of the individual components mixed therewith.

Grass seed is then applied to the layer of growing material at a rate depending on local conditions, but usually * WO 94/18394 PCT/EP94/00317 11 within the range of 25 to 35 g/m2. In the alternative, the layer of growing material may be turfed using turf which has been grown on the same type of sand as used for the growing material. For this application so-called washed turf is 5 preferred.

It is found that using the method of the invention, an all weather grass surface can be prepared which is free-draining, such that even after prolonged periods of heavy rain water will not stand on the surface. The surface remains relatively dry 10 and mud free, to provide a firm footing for sporting activities. In addition, it is found that the surface resists compaction, and the root zone retains a good structure even when subjected to heavy wear under wet conditions. This improves aeration giving the grass ideal growing conditions, 15 and allows healthy and vigorous root development. The result is a thicker, more dense cover of grass.

It is found that the preferred grass surfaces of the invention have greatly improved sheer resistance and stability. The synthetic fibres act like a mass of relatively 20 indestructible roots, and provide a rot proof structure to the root zone. It is believed that the distributed fibres, rather than the grass roots, take the strain from shocks and pressure to the system, and prevent the surface from breaking up. Grass regeneration after winter conditions is very quick because the 25 roots have remained intact. For the same reason, recovery from any shallow divotting is very speedy.

The new all weather grass surface is particularly suitable for sporting areas having high usage, for example equestrian

Claims

26 15 7 4
WO 94/18394 PCT/EP94/00317 12 training areas, the goal mouths and the centre circle of a football pitch, and golf tees.
In the preparation of a sub-base for a surface for sporting and other activities the same procedures are adopted 5 as set out above. The mixture of sand, particulate or fibrous organic material comprising vegetable matter and elongate synthetic fibres is laid out on a prepared site to the required depth as previously described. A so-called "paving" may then be laid on the thus formed sub-base, which, in the case of for 10 example a tennis court or a footpath, can be a clay paving. Other suitable paving materials may of course also be used.
The reader's attention is directed to all papers and documents which are filed concurrently with this specification and which are open to public inspection with this 15 specification, and the contents of all such papers and documents are incorporated herein by reference. 20 25
WO 94/18394 261 574
PCT /EP94/00317 13
CLAIMS 10 15 20 6. 25
8. 2 7 jan
9 la 7997 An improved grass surface in which the grass is grown in a layer of material comprising sand, an organic growth supporting medium and elongate synthetic fibres, the fibres being randomly dispersed as separate individual fibres in the material, and having a fibre length frori 5mm to 75mm. An improved grass surface as claimed in claim l, in which the sand is silica sand and in which the sand particles have an average diameter in the range of from 100 to 1000 microns. A surface according to claim l or 2, in which the organic growth supporting medium is soil, peat, or a mixture thereof. A surface according to any of the preceding claims, which comprises a soil conditioner. A surface according to claim 4, in which the soil conditioner is a seaweed based soil conditioner. A surface according to any of the preceding claims, in which the elongate synthetic fibres have a fibre length from 20 to 40mm. A surface according to any of the preceding claims, in which the fibres have ar average diameter from 50 to 150 denier. A surface according to any of the preceding claims, in which the fibres are polypropylene fibres. A surface according to any of the preceding claims, in which the layer of material is from 50 to 150mm thick. 26 1 57 4 WO 94/18394 PCT/EP94/00317 14
10. A surface according to any of the preceding claims, having an inorganic fertiliser added thereto.
11. A surface according to any of the preceding claims, which comprises from 50 to 95% of silica sand by volume of the 5 total material.
12. a surface according to any of claims l to 10, which comprises from 50 to 95% of sand bonded with water activated clay, by volume of the total material.
13. A surface according to any of the preceding claims, in 10 which the organic growth supporting medium comprises soil which is present in an amount of from 5 to 50% by volume based on the total volume of the material.
14. A surface according to any of claims 1 to 12, in which the organic growth supporting medium comprises peat which 15 is present in an anount of from 5 to 25% by volume based on the total volume of the material.
15. A surface according to any of the preceding claims, in which there is present a seaweed based soil conditioner in an amount of from 50 to l00g/m2, based upon the area of 20 the material layer.
16. a surface according to any of the preceding claims, in which there is present an inorganic fertiliser in an amount of from 10 to 50kg/20 tonnes of total material by weight. 25 17. a surface according to any of the preceding claims, in which the percentage of synthetic fibres in the material is in the ranee of 0.1 to 0.9% by weight based on the total weight of the material. ^ 27
*MA/ 26 1 5 7 4
WO 94/18394
PCT/EP94/00317 15 5 19.
20.
21. 15
22. 20
23. A surface according to any of the preceding claims, in which the percentage of synthetic fibres in the material is in the range of 0.25 to 0.5% by weight, based upon the total weight of the composition. A method of forming an all weather grass surface, which comprises sowing grass seed in, or applying turf to, a layer of material comprising sand, an organic growth supporting medium and elongate synthetic fibres, the fibres being randomly dispersed as separate individual fibres in the growing material, and having a length from 5mm to 75 mm. A method according to claim IS', in which the sand and the fibres are pre-mixed in a high intensity mixer. A method according to claiu 19 or 20, in which the growing material has mixed therewith a soil conditioner and/or an inorganic fertiliser. A growing material for a grass surface, which material comprises sand, an organic growth supporting medium and elongate synthetic fibres, the fibres being randomly dispersed as separate individual fibres in the material, and having a fibre length from 5mm to 75mm. A sub-base for a surface for sporting and/or othor activities which comprises a layer of material comprising a mixture of sand, a particulate or fibrous organic material comprising vegetable matter and elongate synthetic fibres, the fibres being randomly dispersed as separate individual fibres in the mixture and having a fibre length of from 5mm to 75mm. 26 1 5 7 A 16
24. An improved grass surface substantially as herein described with reference to the accompanying drawings RUS8ELL AkVPioii i.»., .. VpV AU®1 per ATTORNEYS FOR THE APPLICANT