GB2196539A

GB2196539A - Substructure construction for an artificial grass field

Info

Publication number: GB2196539A
Application number: GB08721600A
Authority: GB
Inventors: Josephus Cornelis Heerkens
Original assignee: Wegenbouwmaatschappij J Heijmans BV
Current assignee: Wegenbouwmaatschappij J Heijmans BV
Priority date: 1986-09-15
Filing date: 1987-09-14
Publication date: 1988-05-05
Anticipated expiration: 2007-09-14
Also published as: NL8602322A; DE3761316D1; ATE49251T1; ES2005323A6; EP0260769B1; EP0260769A1; GB8721600D0; GB2196539B

Abstract

A method of providing a substructure construction for an artificial grassfield by providing a foundation on a layer of sand which is present or has been provided, said foundation for the larger part consisting of natural round sand or river sand to which a material of organic orgin is added in an amount of more than 1 weight %, calculated on the quantity of sand, whereby 60-70 weight % of river sand is distributed evenly among a quantity of 40-30 weight % of rubber particles.

Description

GB2196539A 1 SPECIFICATION together by a binding agent there was strewn a

layer of sand. In practice, however, such a Method of providing a substructure con- construction proved to be unsatisfactory be struction for an artificial grassfield and an cause the layers strewn in were of a too re artificial grassfield having such a substruc- 70 silient nature. Furthermore an artificial grassfi ture construction eld is described in the US patent 4,497,853 in which an understructure construction is ap The invention relates to a method for provid- plied having a layer of coir fibres, protected ing a substructure construction for an artificial by a layer impervious to water. Said construs grassfield by providing a foundation on a layer 75 tion is costly because it is built up from an of sand which is present or has been pro- substructure construction comprising at least vided, said foundation for the larger part con- three layers and moreover the artificial grassfi sisting of natural round sand or river sand to eld thus obtained does not have the desired which a material of organic origin is added in damping.

an amount of more than 1 weight % on basis 80 An improved substructure construction for of the sand. The invention futhermore relates an artificial grassfield which can especially be to an artificial grassfield, having such a sub- used for soccer because a better damping is structure construction, which can be used for obtained, is known from the European paten practising various sports, especially soccer. specification 0,136,747. The substructure

In the past decade the interest in artificial 85 construction described therein is composed of grass has constantly increased as it is posunbroken sand which is mixed with at least 1 sible on these fields to practise sport in prac- per cent by weight of a fibrous material, for tically all weather conditions without having to which purpose polypropylene fibres, Nylon be afraid that the field will have to be rejected fibres or glass fibres have been mentioned.

and because a field of artificial grass can be 90 From further measurements and observations used much more intensively than a field of it has become apparent that the optimum re natural grass. A field of artificial grass strewn sult which can be obtained with a substruc in with sand can be used for about 2000 ture construction for an artificial grassfield hours per year without any problems, whereas with regard to the flatness and the damping a field of natural grass can be played on for 95 power can be improved by a substructure an average of 250-300 hours per year. Also construction according to the invention. Said the cost of maintenance is considerably lower substructure construction can be laid accord for an artificial grassfield as it amounts to ap- ing to a method as mentioned in the preamble proximately Dfl. 3000,-per field per year, and it is characterized in that 60-70 per cent whereas for a field of natural grass the aver- 100 by weight of river sand is distributed evenly age cost is Dfl. 20,000.-per field per year. amoung a quantity of 40-30 per cent by

Because of these advantages more and weight of rubber particles. The results ob- more fields of artificial grass are being laid, tained with the application of rubber particles which are used especially for playing hockey. when laying fields of artificial grass whereby

Such fields of artificial grass are also known in 105 rubber grains were used in the top layer, as the patent literature, especially since the publi- mentioned in the US patent 4,396,653, were cation of the US patent 3,995,079, published so bad, especially because of the separation in 1976. At that time a great deal of attention that occurred when no binding agent was was paid to the provision of a filling material used and because of the resilient action when between the fibres forming the artificial grass, 110 a binding agent was used for the rubber par so that on the one hand the fields of artificial ticles, that the use of rubber particles in artifi grass could be laid down cheaper because cial grassfields has been considered to be un less fiber material was required and on the desirable. It is all the more suprising, there other the field got properties which were bet- fore, that not it has been discovered that ter comparable with those of a natural field. 115 when rubber particles are used in the sub

For playing hockey on a field of artificial grass structure construction in a specific way it is it is especially important that the field is flat possible to obtain a good result after all. The and furthermore the damping or softness is use of resilient particles as such in a ground important. For a soccer field, on the other layer has been described in the British patent hand, the damping is the most important facapplication 2,132,903, but there the particles tor because with soccer the players make of the resilient material, such as grains of syn more movements such as jumping and making thetic rubber, plastic materials, cork and the slidings than with hockey. It has been tried to like are provided in a fibrous structure of e.g.

vary the damping of artificial grass by partly polyamide fibres. This construction is costly substituting the layer of sand which was 125 because of the use of the polyamide fibres strewn between the fibres for an other ma- and it has a considerably looser structure than terial such as rubber particles being connected the layer consisting of the matrix of rubber together by means of a binding agent, as de- particles, whereby the hollow spaces are filled scribed in the US patent specification with sand as applied according to the present

4,396,653. On said rubber grains connected 130 patent application. Besides, tests have shown 2 GB2196539A 2 that the damping value for a soccer field hav- same weight, which implies that because of ing a substructure according to the invention the lower specific weight of rubber the rubber is better than with the ground layer as de- particles are bigger than the sand grains. Thus scribed in said British patent application. the rubber grains form the damping skeleton With the construction according to the in- 70 of the foundation whereby displacements or vention it appeared to be possible that the deformations are as much as possible inhi substructure construction is up to the high bited by the sand filling.

standards required for an artificial grassfield The invention will be further explained with for playing soccer. The main consideration reference to the following example.

thereby is the playing comfort and the damp- 75 ing of the total construction. The damping Example power of the total construction is mainly de- The terrain where an artificial grassfield is to termined by the construction of the substruc- be laid down is dug away up to the frost ture. Said damping power is especially impor- limit. On the bottom groundlayer there is pos tant when the sportsman comes down after a 80 sibly laid a drainage system consisting of jump, whereby the sportsman should have the pipes for discharging any excess of water.

same feeling as on a natural field. When the Then a sand bed is provided to a height of damping power is too small the playing sur- about 12 cm under the edge, said sand being face is relatively hard and the chance of get- chosen from moderately coarse sand being ting injured is too great. Therefore it is very 85 previous to water and having a particle size of difficult to construct a substructure construc- 180,um-300,um. On this the foundation layer tion for a field of artificial grass whereby the was provided, said layer consisting of a mix final result is that the sportsman experiences ture of 67 weight % of river sand and 33 the artificial grass as much as possible the weight % of rubber particles, said rubber par same as a field of natural grass. This has only 90 ticles having been obtained from mechanically appeared to be possible with the construction ground car tyres. The rubber particles had a according to the present invention and not screen size of 7-11 mm and the sand con with the application of the comparatively elas- sisted of natural round sand or river sand tic intermediate layer with bound rubber granu- whose particle sizes were between 0.2 and 2 lates in the synthetic fibres. Besides there is 95 mm, 80% being larger that 0.5 mm. The mix no natural build-up of the layers with known ture of rubber and sand was obtained by add constructions as described in the British pa- ing sand to the rubber in an intensive mixer, tent application 2.132,903 and the US patents so that the open spaces between the rubber 4,396,653 and 4,497,853, as a result of particles were filled with sand. The layer of which the differences in properties between 100 rubber and sand thus provided on the sand the various layers composing the construction bed formed a rubber skeleton whose open are too great, which the sportsman, when spaces were willed with sand particles, so making sudden movements, experiences as that the freedom of movement of the rubber unpleasant. particles was strongly restricted by the sand.

According to a preferred embodiment with 105 On this bed of rubber and sand a film of the method according to the invention the rub- porous material was then provided and finally ber particles may originate from mechanically the artificial grass. With this construction an ground car tyres, the larger part of the rubber artificial grassfield has been obtained suitable particles having a screen size of 2-11 mm for playing soccer.

and being free of textile and steel. On filling 110

Claims

the rubber matrix with sand, up to 10 per CLAIMS cent by weight of water

is added during the - 1. A method of providing a substructure mixing of sand and rubber particles in order to construction for an artificial grassfield by pro aid the filling of the open spaces among the viding a foundation on a layer of sand which rubber particles. The mixture of rubber and 115 is present or has been provided, said founda sand is provided on the foundation to a height tion for the larger part consisting of natural of 4-20 cm, preferably to a height of about 7 round sand or river sand to which a material cm. When the grains have just a bit freedom of organic orgin is added in an amount of of movement the foundation can absorb corn- more than 1 weight %, calculated on the paratively little energy and the ground layer is 120 quantity of sand, characterized in that 60-70 experienced as being ---hard---. On the other weight % of river sand is distrubuted evenly hand high damping power corresponds with a among a quantity of 40-30 weight % of rub high absorption of energy. In order to absorb ber particles.

the energy to a sufficient degree under high
2. The method according to claim 1, char- loads using a foundation according to the in- 125 acterized in that the rubber particles originate vention, the layer has a thickness of at least 6 from mechanically ground car tyres, the larger cm. part of the particles having a screen size of In order to avoid separation of the layer 2-11 mm and being free of textile and of comprising rubber and sand it is preferred to steel.

use rubber and sand grains having about the 130
3. The method according to claims 1-2, 3 GB2196539A 3 characterized in that the filling of the rubber matrix by sand particles is stimulated by add ing up to 10 weight % of water during the mixing of sand and rubber particles.
4. The method according to claims 1-3, characterized in that the mixture of rubber and sand is provided on the foundation to a height of 4-20 cm.
5. The method according to claims 1-4, characterised in that the rubber particles and sand grains have substantially the same weight.
6. A field of artificial grass consisting of a substructure construction and an upper layer with synthetic fibres, characterized in that the substructure construction is applied as de scribed in claims 1-5.

Published 1988atThe Patent Office, State House, 66/71 High Holborn, London WC 1 R 4TP. Further copies may be obtained from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD.

Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.