Note: Descriptions are shown in the official language in which they were submitted.
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ALL WEATHER SURFACES
FIELD OF THE INVENTION
The present invention relates to all weather surfaces
and more particularly to surfaces suitable for equestrian
events.
8ACXGRO~ND OF THE INVENTION
. .
The natural surface for most sporting events,
particularly horse jumping, is grass. This is acceptable
for large areas such as race courses where the usage is
low and the 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. In the summer turf can become hard and this
may lead to an unacceptable incidence of leg injuries.
This also applies to frosty weather. Thus for an exercise
and/or all weather race track area grass is not
acceptable,
As an alternative to grass a number of artificial
surfaces have been used. A first known surface comprises
natur~l wood fibre and this when new provides a good
surface. It is however a natual material and therefore
deteriorates with age. Thus it has to be replaced and
since it is fairly expensive the replacement cost is high.
A second known surface comprises finely chopped P.V.C.
often from used cable 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 high. A third known surface comprises ashes from
power 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 silica sand which provides a good
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surface in wet weather conditions but in dry weather
conditions the sand provides an extremely difficult
surrace for both jumping and landing particularly for an
e~uestrian practise ring. The principal problem of silica
sand is that it lacks cohesion therefore providing a
surface which is described as riding too deep and loose.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide
an all weather surface which is acceptable in both wet and
dry conditions for all types of practise arenas.
The present invention therefore provides an all
weather surface for equestrian events comprising a layer
of material laid on top of a prepared drainage base, the
material comprising a mixture of sand and elongate
synthetic fibres, the fibres being randomly dispersed as
separate individual fibres throughout the sand to produce
a relatively soft surface and in which the fibres are in
the range of one to three inches (25 to 75mm) in length
and are of an uncrimped form.
P_eferably the sand particles are in the range from
100 to 1000 ~m. A selected range of fibre length is
between 35 to 50 mm.
Preferably the layer is between 75 mm and 150 mm
thick. The diameter of fibres is 50 to 150 denier. A
preferred value is in the region of 100 denier and a depth
of layer of 100 mm.
The fibres are preferably of any polymeric or
inorganic material but preferably polypropylene in an
uncximped form commonly referred to as straight staple
fibre. The percentage of fibre in the mixture is
preferably in the region of 0.1 to 0.5% by weight with a
preferred value of 0.3% and a preferred range of 0.25 to
.45%.
The sand may be silica sand, or a sand bonded with
water activated clay or a sand bonded with an organic
li~uid activated clay.
When a silica sand mixture is ùsed the percentage of
fibres preferred is in the range from 0.25 to 0.45~ by
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weight. For a sand bonded with water activated clay or an
organic liquid activated clay the percentage of fibres
preferred is in the range from 0.1 to 0.4% by weight.
The fibres may be coloured to conform to the colour
of the sand and thereby being substantially invisible in
use.
DESCRIPTION OF THE PREFERRED EMBODIMENT
There are three main types of sand which are suitable
for riding surfaces namely silica sand, sand bonded with
water activated clay and sand bonded with an organic fluid
activated clay. Each of these types of sand, when
combined with the fibres in a substantially homogenous
manner produces a good surface for a horse riding practise
area but each has its own characteristic making it more
suitable for certain conditions. Each type has been tried
in practical tests as follows:-
1. Silica Sand
This is a sand which is relatively clean is clay freeand is a well graded sand produced by a wet classification
method. In practise when mixed with the fibre the mixture
is suitable for both indoor and outdoor use. The mixture
requires a relatively high fibre content and a preferred
range is between 0.25 to 0.45% by weight of fibre. This
is because the sand prior to mixing with the~ fibre is
relatively free to move and therefore requires a
relatively high fibre content to effect the desired
result.
The silica sand and fibre mixture is particularly
suited to outdoor use in high rainfall areas because it
drains freely, especially if laid on a well draining sub
layer. It may be used indoors where it benefits from
regular spraying with water to produce a good surface for
riding. Alternatively a water retaining agent such as
calcium chloride may be applied to the sand to assist in
retaining the moisture within the sand.
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2. Sand bonded with water activated clay
This is a sand in which the sand particles are coated
with a water 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.
When sprayed with water during use this sand with the
fibre mixed therein retains the water. Thus, it is
suitable for indoor use where a single wetting operation
will be sufficient to maintain the surface in a desired
condition for a relatively long period of time. Dependent
on the amount of clay the mixture may not be particularly
suited to outdoor use especially in "wet" climates. In
dry climates however, the water retentive property of the
added clay may be beneficial in reducing the amount of
spraying necessary if a heavier surface is required.
Because of the characteristic of the sand the amount of
fibre included does not need to be as much as in the
silica sand mixture, and a preferred range of 0.1 to 0.4%
by weight is found to be most practical.
3. Sand bonded with an organic liquid activated clay
This is a sand in which the particles are coated with
an organo-clay complex - that is activated by an.organic
chemical such as oil. The degree of cohesive strength
produced in the sand is dependent upon the amounts of
organo-clay complex and oil.
This type of clay when combined with the fibre as a
mixture is not substantially affected by water. Thus, the
mixture is suitable for both indoor and outdoor use. When
used indoors it does not require watering and when used
outside rain will not substantially affect the surface
because the water will drain through or run off but will
not cause the sand to bind more closely together. In
climates where frost is common this mixture is
particularly advantageous because it does not freeze in
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the same manner as the sand with water activated clay or
the silica sand. Dependent on the oil selected the
freezing point will normally be below minus twenty degrees
Centigrade and therefore when used outside any practise
area can be made greater use of in cold weather without
risk of damage to, for example, horses due to frozen
ground.
A disadvantage with the sand bonded with an organic
liquid activated clay is in the cost, since this type of
mixture will be more expensive than the silica sand or
sand with water activated clay.
Because the sand is bonded with a clay the fibre
content required for a good surface is not as high as for
silica sand and a preferred range of from 0.1 to 0.4% by
weight is found to give good practical results.
The sand and fibre need to be mixed to a
substantially homogenous mixture to thereby distribute the
fibre evenly and randomly throughout the sand. Though a
low density ratio by weight is used the fibre being of a
significantly lower bulk density is present in a random
dispersion throughout the mixture.
The all weather surface is prepared in a first
example by digging out turf and top soil to a depth of
approximately 10 cm (100 mm) layer from a turf surface. A
mixture of sand and fibre is used to replace the removed
soil. A greater depth of soil may be removed 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 mixture is prepared by taking a ~uantity (usually
several tons) of sand which is in a fairly moist condition
and mixing into the sand a quantity of polypropylene
fibres which are 35 to 50 mm in length. The sand is
.
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preferably selected to be between 100 to 1000 um in
particle size with particles of rounded to sub-angular
shape and the fibres are mixed for example in a high
intensity mixer of the contra rotating type which mixes
the fibres homogenously in a randomly oriented
distribution throughout the sand.
The random dispersion of fibres reinforces the sand
imparting resistance to particle movement under load from
the horses hooves etc. thus minimizing spreading and hoof
penetration such that a sure footing is obtained. This
effect is obtained under both wet or dry conditions.
The fibre lengths require to be long enough such that
a "cross-linking" effect is produced thereby preventing
the sand from moving under the pressure of the horses
hooves.
Thus the particle size of the sand and the diameter
and length of the fibres requires to be carefully selected
to produce the desired effect.
Relatively straight (i.e. uncrimped) fibres need to
be used since crimped fibres are not readily mixed to
produce a substantially "homogenous" mixture. The length
of the fibres is of particular importance since this
provides, in the homogenous mixture, the cross-linking
which is necessary to prevent the mixture from spreading
under the shock loading produced by horses hooves.
; Following mixing in the contra rotating high
intensity or other high intensity type mixer the mixture
is delivered to the prepared site and laid out to a depth
of between 5 to 15 cm (2 to 6 inches) or more preferably
307.5 to 12.5 cm to give the desired surface characteristic.
The characteristic of the surface can be altered by
the choice of sand particle size and the percentage of
fibre mixed into the sand.
- Further drainage may be obtained in the normal manner
35by providing a layer of gravel beneath the sand layer.
