EP0314622A2 - Sports- or playground - Google Patents

Abstract

The sports- or playground has a covering which contains bark material in particle form and consists at least predominantly of a mixture of bark material and flexible fibres distributed therein, these fibres, at least for the most part, having lengths which are greater than the average greatest dimension of the bark material particles. <??>Shortly after installation, such a covering offers in practice its desired end properties and a uniform water permeability which is substantially independent of local loading.

Description

The invention relates to a sports or playground area with a covering that contains particulate bark material. The term "covering" or "bark covering" is used in analogy to the "turf covering" of a "turf area" according to DIN 18035 (1973) to denote a covering layer of sports areas or playground areas generally consisting of bulk material.

EP-PS 0 096 908 by the applicant describes a sports area with a covering consisting at least partially of particulate bark material, the tread resistance required, in particular for football and similar sports fields, being achieved by means of a multi-layer construction or installation. Furthermore, it is known for running tracks or playgrounds without any special requirements regarding the resistance to bark to be used in simple fill or layering. For the well-known sports areas, fresh or at least slightly rinded bark material (natural color or light brown) is generally used.

It has been found, surprisingly and contrary to the technical expectation, that an advantageous coating can be obtained even and in particular when using more rotten bark material if the rotten bark material is used together with relatively low proportions of fibers, which in turn are relatively resistant to rot.

The new sports or playground area according to the invention has the features specified in claim 1. Preferred embodiments have the features specified in claims 2 to 8. The use as a football field is a preferred example.

The invention also relates to a new method for producing a sports or playground surface with a covering that contains particulate bark material. The method according to the invention is characterized by the features specified in claim 9.

It was found that tree bark, even with different origins under the conditions of natural (i.e. not artificially inhibited) or accelerated rotting (e.g. with optimal temperature control to accelerate the microbiological rotting mechanisms), reaches a state in which the rotting-related change in the physical and chemical properties contributes normal environmental conditions almost come to a standstill before the typical structure of the particles disappears.

The use of such a material for covering sports and playground areas would be desirable in particular for two reasons:
- On the one hand, one would not need any red-inhibiting additives for such areas, which not only reduces the costs, but also excludes that additives could get into the groundwater.
- Secondly, such a surface would have its final strength practically immediately after installation, ie it would change less over time than a covering made from fresh or only slightly rinded bark.

Furthermore, contrary to expectations, it was found that a covering of rotted bark material generally has a usable water permeability even if it contains considerable proportions of fine rotted bark particles, for example up to 50% by weight or more of particles of <2 mm. Finally was found that even with a covering made of rinded bark material, the water permeability is determined more by the substructure than by the covering, even if the latter is made from sieved rotted bark material that passes completely through a sieve with a mesh size of 2 mm.

The addition of fibers according to the invention enables very good properties with regard to the resistance to tread and the coherence of the covering of sports or playground surfaces according to the invention to be achieved even with comparatively small fiber fractions in the range from 0.01 to 0.1% by weight, based on the dry weight of the bark material. if the covering with layer thicknesses of more than 10 mm and e.g. 30 to 150 mm is installed. Larger flooring thicknesses are possible, but usually do not bring advantages that offset the higher costs. Fiber proportions of 0.1 to 5% by weight are preferred for many purposes; Fractions above 10% by weight (always based on the dry weight of the bark fraction of the mixture) usually do not bring the benefits justifying the necessary costs.

The term "fibers" is general and is to be understood in the sense that it can be a flexible structure of any cross-section, which has a considerable, e.g. have at least 50 times the length dimension. The fibers are preferably relatively resistant to rotting, i.e. should not show any significant changes within a period of at least 12 months in mixture with the rotted bark particles and any other additives under normal weather and moisture conditions.

Mineral or organic fibers of natural or synthetic origin are generally suitable for this, including Lich of vegetable fibers and / or fibers which can be obtained by cutting synthetic fibers or from fiber ribbons. Specific examples are natural hard fibers, such as coconut or hemp fibers, and synthetic staple fibers made from polyalkylenes, such as polyethylene or polypropylene, saturated polyesters, for example from phthalic acid and glycols, and polyamides, for example nylon. Other fibers that are insoluble in water and are preferably not swellable therein can also be used. In particular, regenerated materials can also be used, as can be obtained by various methods, including cutting, shredding or other processing methods.

Relatively rott-resistant fibers are preferred: the rotting resistance can be tested accelerated in the warming cabinet at 35 ° C in the presence of moisture and aerobic or anaerobic rotting fungi or bacteria; significant changes, e.g. the color or / and strength of the within a predetermined period, e.g. 30-60 days or more of tested material indicate lower resistance to rotting. Relative values are usually sufficient, i.e. when tested under the same conditions, the preferred fibers should not be less resistant to rotting than the bark material particles.

Preferred fibers have thicknesses in the range of 0.01 mm-1 mm, preferably 0.05-0.5 mm, which, however, also depends on the tensile strength; the fiber titers (as far as determinable) can range from 1 to 1000 den. Generally preferred are those fibers whose fiber structure can still be seen after more than 12 months in a mixture with the bark particles that is exposed to the weather.

For many uses it is preferred to use a certain amount of fiber e.g. 50 to 500 g per m² surface of the covering, i.e. without inevitable coupling between covering thickness and fiber content. This is particularly useful when using relatively long fibers. The fibers can be used in whole or in part as bundles or yarns if this is appropriate for cost reasons. Otherwise, monofilament fibers or threads or filaments are preferred. Structured or textured fibers are suitable as far as the costs allow.

In order to give the covering the desired strength, in particular resistance to treading, the fibers must have at least the majority (i.e., 50% of their total amount exceeding) fiber lengths that are greater than the average largest dimensions of the bark material particles. In practice, the sieve count of the bark particles can be used, e.g. 0-40 mm, 0-50 mm or 10-80 mm and the lengths of the fibers dimensioned accordingly, i.e. e.g. choose a corresponding mean fiber length of over 40 mm or over 50 mm or 80 mm, i.e. typically in the range 50-150 mm or more.

For most applications, the mixture of bark material and fibers forms the major part of the covering of a sports or playground area according to the invention, i.e. more than 50% and usually 75 to 100% of the weight of the dry components of the covering.

A naturally or artificially rotted material can be used as the bark material, as is available at temperatures from 50 to 80 ° C. and rotting times from a few weeks to months. On the other hand, a bark material naturally rotted in the normal ambient conditions outdoors can be used, or a mixture of more and less rotted bark material can be used. Also one when converting Material from surfaces covered with bark can be used with or without the addition of new material.

The degree of rotting of bark material can also be determined approximately by color determination: a bark material that is more or less stabilized by rotting is preferred for many applications. It is believed that such stabilization occurs when the cellulose portion of the bark is largely removed by microbial degradation and the residue consists mainly of lignin. The C: N value of the bark material as such, i.e. H. without additives, is preferably at least about 70 and preferably about 100 (± 10).

The origin of the rotted bark material from certain tree species is comparatively less critical, which means a further advantage of the invention. Pine bark is a preferred example; a typical mixture contains e.g. B. about 70% by weight of pine bark and about 30% by weight of spruce bark.

In general, the color value according to DIN color chart (DIN 6164) of rotten bark is practically independent of the origin of the bark at a darkness level D of at least D3 and preferably in the range from D4 to D6. Fresh or only slightly rotten bark material, on the other hand, usually has a D value of 1 or 2 and only exceptionally one of 3.

The fibers can be distributed or mixed in or with the preferably rotted bark material by turning methods or in mixing or shredding systems. Drum or roller mixers or mixers with rotating distributor elements can be used. A particularly high shear effect or mixing intensity of the distributor or mixing device is usually not necessary and can be disadvantageous under certain circumstances, for example when using long or “endless” fibers or filaments. Generally one can be sufficient Even distribution of the fibers in the bark material can be achieved with mixing times of 10 to 30 minutes. The control of the degree of distribution of the fibers can be determined by statistical sampling, weighing the mixtures and washing out the fibers. The deviations from ten samples should preferably not exceed on average 20% of the mean.

The sieve numbers given here can generally be determined according to the Swiss industrial standards (SSV standards), especially SN 670808 (sieves), SN 67O810B (sieve test), SN 670812A (dry sieving) and SN 670814A (wet sieving), if you compare the bark material to mineral goods essential differences (density, strength) are taken into account accordingly and particle size reduction during sieving is minimized if necessary by wet sieving and limitation of the sieving machine running time (10 min).

The C: N ratio is determined as a weight ratio (carbon fraction: nitrogen fraction) in a conventional manner by elemental analysis of the dry bark (nitrogen according to Kjeldahl; carbon over CO₂).

In the case of bark material, the "dry weight" is the weight determined after drying at 105 ° C. to constant weight (24 hours).

Mixing can take place with air-dry components or with moist material or with the addition of water; the amount of water present or added during mixing generally depends on the distance between the installation location and the mixing system in order to avoid unnecessary transport masses.

Since the finished covering should normally contain water close to saturation, this is either introduced when mixing or / and only during the course of installation or shortly afterwards. The location and time of the addition of the main water content can be selected for economy.

In order to produce a sports or playground area according to the invention, the substrate or substructure prepared in the customary manner can be used with or without intermediate layers in the manner of the filter, base or compensation layers explained in EP patent 0 096 908 with or without a dynamic layer and optionally under Use geotextiles as intermediate layers to apply the covering made of bark material and fibers and distribute and compact them in the usual way for fillings.

The covering of sports or playground areas according to the invention may contain further, preferably granular components, e.g. B. mineral grain with sieve sizes of, for example, up to 2 mm, such as, in particular, sand, provided that and as long as no disadvantageous segregation phenomena occur.

Laboratory tests with coverings according to the invention show that not only are no disadvantages to be feared for the groundwater, but that the surface of sports or playground surfaces according to the invention can act as biological filter layers; Such areas could therefore even be used to purify waste water if necessary.

The flexibility or the generally preferred strength of the fibers used according to the invention is generally given with the above-mentioned organic fibers; it can be defective in the case of brittle mineral fibers. This property can usually be checked simply by repeatedly bending a given fiber back on itself and stretching it again without this leading to breakage.

Laboratory tests have confirmed that a surface according to the invention solves the problem that occurs with known bark covering surfaces in areas of particularly high mechanical stress: in such areas, the bark particles can be comminuted to a greater extent, which leads to a lower average in these areas Particle size leads than in the less stressed parts. This reduces the water flow rate in the stressed areas; In spite of a still sufficient water permeability, these areas can then have a stronger light reflection during heavy rainfalls and thereby give the impression that it is not correct per se that local wet spots or even puddles would form on or in the covering.

For a covering made of bark material, which mainly consists of relatively fine material and e.g. predominantly has particle sizes corresponding to sieve numbers from 0 to 30 (mm), the fibers can be used to ensure a sufficient and practically uniform water permeability speed of the covering, even in relatively heavily used covering areas.

The fibers in the covering of a sports or playground area according to the invention therefore have not only a strengthening effect, but also an effect which increases the uniformity of the water permeability, in particular if the mean fiber length is approximately at least as large as the thickness of the covering and thereby the fiber distribution or mechanical strength of the fibers or a relationship formed by them by "tangling" (e.g. in the manner of a loose tangled fiber mat) approximates the model of the root system of lawn surfaces . Accordingly, a more or less statistical positional distribution of the fibers, including a loose tangle, is preferred over a largely identical spatial orientation of the fibers for many purposes. You can also distribute the fibers oriented in the covering, e.g. B. in the form of mat or carpet-like structures in which the fibers are more or less strongly bound and then, for. B. by sprinkling with the bark material. In general, it goes without saying that the running resistance caused by the covering or the fibers contained therein should not be significantly greater for sports areas, in particular soccer fields, than for a sports area with a lawn surface.

When using natural fibers, those with a lignin content (determination method according to Hägglund, E. in "Holzchemie", 2nd edition, page 225, or according to Halse, OM in "Papier-Journalen" 10/1926/121) of at least about 10 % By weight, e.g. B. with a lignin content of 10 to 50 wt.% Or more.

example 1

A soccer field was produced essentially as described in EP-PS 0 096 908 with the modification that the top layer was produced from a mixture which was 1.3 per m³ of bark material (grain size 0-50 mm; dry weight approx. 250 kg) kg of coconut fibers contained. The mixture was applied in a single pass in a layer thickness of 10 cm, rolled and saturated with water; the fibers were mixed with the bark material in a barrel mixer for continuous operation.

Example 2

The procedure was as in Example 1, with the modification that the top layer was applied in two steps. The lower sub-layer consisted of bark material (grain size 0-50 mm) with fiber admixture, which was applied in a thickness of 8 cm.

Then a fiber-free mixture (grain size 0-20 mm) of 2 cm was applied without special sealing of the lower part and compacted by rolling.

The entire layer of bark was then saturated with water.

Example 3

For test purposes, a plurality of surface areas of approx. 1 m² each were applied to mixtures of bark material with different degrees of rotting and with different fiber content on a water-permeable substructure with drainage and, after saturation with water, tested for water permeability and step resistance.

The water permeability test consisted of pouring about 50 liters of water on the surface to be tested and measuring the time until a reflecting water surface on the surface of the covering disappeared. Expiry times of less than 300 seconds were rated as "good water permeability", those over 500 seconds as "poor water permeability".

Impact resistance was assessed by putting on a single soccer shoe (with normal studs) under a load of 40 kg and testing the sinking. If, when viewed from the side, there was still a light passage between the studs and the sole, the covering was rated as "tread-resistant".

• (A) aus stark gerottetem Rindenmaterial (Körnung 0-50 mm) und mindestens 0,5 Gew.% Kokosfasern (jeweils auf Trok­kenbasis),
• (B) aus schwach gerottetem Rindenmaterial (Körnung 0-50 mm) und mindestens 0,2 Gew.% Kokosfasern,
• (C) aus Mischung A mit Beimengung von 10 Gew.% Quarzsand wasserdurchlässige trittfeste Beläge ergeben.

It was found that mixtures

• (A) from heavily rotted bark material (grain size 0-50 mm) and at least 0.5% by weight coconut fibers (each on a dry basis),
• (B) from weakly rotted bark material (grain size 0-50 mm) and at least 0.2% by weight of coconut fibers,
• (C) from mixture A with admixture of 10% by weight quartz sand result in water-permeable, hard-wearing coverings.

If the fiber content is increased to 2% by weight, the tread resistance and water permeability will be significantly better. Above about 2% by weight, there is no significant improvement.

Claims (10)

1. Sports or playground area with a covering which contains particulate bark material, characterized in that the covering consists at least predominantly of a mixture of bark material particles with flexible fibers distributed therein, at least for the most part having lengths which are greater than the average largest dimension the bark material particles. 2. Surface according to claim 1, characterized in that the bark material particles have a sieve size of less than 50 mm and the fibers have at least for the most part lengths of at least 50 mm. 3. Surface according to claim 1 or 2, characterized in that the fibers are at least as resistant to rotting as the bark material particles, which in turn consist at least partially of rotted particles. 4. Surface according to one of claims 1 to 3, characterized in that the fibers are contained in proportions of 0.01 to 10% of the dry weight of the bark material particles in the mixture, preferably so that the covering has a thickness of 30 to 150 mm and has a fiber content of 50 to 1000 g / m². 5. Surface according to one of claims 1 to 4, characterized in that the fibers have thicknesses of 0.01 to 1 mm. 6. Surface according to one of claims 1 to 5, characterized in that the bark material particles have a C: N value of at least about 70, preferably at least about 100. 7. Surface according to one of claims 1 to 6, characterized in that the bark material particles have a degree of rotting corresponding to a dark brown humic acid color. 8. Surface according to one of claims 1 to 7, characterized in that the fibers at least partially consist of vegetable hard fibers and / or organic synthetic fibers. 9. A method for producing a sports or playground area with a covering which contains bark material particles, characterized in that the covering is formed from a mixture of bark material particles and flexible fibers distributed therein, which at least for the most part have lengths which are greater than that largest average size of the bark material particles. 10. The method according to claim 9, characterized in that a mixture of rotten bark material and the fibers is installed in a moist state and / or during or immediately after installation with water, preferably until saturated.