EP3130704B2 - Fibre-reinforced turf support layer and method of processing thereof - Google Patents

Description

The invention relates to a base layer for turf which has reinforcing fibers made of plastic, these reinforcing fibers being essentially non-biodegradable under the environmental conditions when used as a base layer in the soil. In addition, the invention also relates to a method for preparing a base layer for lawns. Such a base layer is from the WO2012159145A1 known. In research, one has also dealt with biodegradable reinforcements for turf base layers, in which fibers based on PLA (polylactide) are used (IGF research project AIF 15494 BG, Fraunhofer UMSICHT, FITR eV on the topic "Fiber-reinforced soil - fiber reinforcement of fine-grained recycling materials and excavated soil for use in earthworks and civil engineering").

Many popular sports such as football, hockey or equestrian sports are preferably practiced on lawns. With intensive use of natural lawns for such sports, the lawns quickly wear out. This wear and tear can go so far that the lawns can no longer be used for sporting activities. Longer care and regeneration phases are then required for the lawn areas, during which no sport can be practiced there. However, longer downtimes due to wear and tear on the lawn are undesirable for operators of sports fields.

One approach to countering this problem is the use of artificial turf, which is made of synthetic materials and therefore wears out less quickly. However, even modern artificial turf does not behave in the same way as a natural turf when performing most sports. Thus, in many cases, artificial turf is unpopular with athletes.

Another alternative to improve the wear resistance of turf is to use hybrid turf. Hybrid turf combines the benefits of a natural turf surface with the benefits of reinforcement using synthetic materials. With such hybrid lawns, a synthetic fiber-reinforced base layer is first applied to the existing subsoil. The synthetic fibers in this base layer have the task of improving the shear strength of the layer by networking with one another. Mechanical loads when doing sports are thus better absorbed and distributed than with a floor that is not reinforced with fibers. Natural grass is then laid on top of this base layer. The reinforcing fibers of the base layer can also run into the natural turf, which also gives the turf layer additional stability. Such a hybrid turf or its base layer also has a finite lifespan and must be renewed or replaced after a few years.

When disposing of used hybrid turf, the problem then arises that the synthetic fibers are inseparably mixed with the mineral and organic components of the turf and base layer. Therefore, large amounts of removed material occur every year when renewing hybrid lawns, which contain not only natural material but also a large proportion of plastics. Such material containing plastic cannot be used in nature and must therefore be dumped or disposed of in a laborious and costly manner.

The object of the present invention is therefore to simplify the disposal of used base layers of hybrid turf.

The object of the invention is achieved by a base layer having the features of claim 1. A base layer according to the invention has reinforcing fibers made of a plastic material which is essentially not biodegradable under the environmental conditions when used as a base layer in the soil or otherwise under conditions during normal use of the hybrid turf (e.g. temperatures, humidity/water content, radiation, in particular UV -Radiation) is decomposed, whereby the reinforcement fibers are randomly distributed in different directions within the base layer and there is at least partial interlocking between the individual reinforcement fibers, the proportion of reinforcement fibers in the base layer being between 0.1 and 4% by weight and this Reinforcement fibers have an activation threshold above which the reinforcement fibers are essentially completely biodegradable, the activation threshold being a temperature higher than 50°C and the reinforcement fibers consist of a material from the group of polyvinyl alcohols (PVA). n. This means that the reinforcing fibers do not change their properties during use in the base layer of a hybrid turf, or only to a very small extent. This ensures that these reinforcement fibers reliably fulfill their task of mechanical support and strengthening of the base layer over a period of several years, since their mechanical properties remain essentially constant. The reinforcement fibers of a base layer according to the invention have an activation threshold above which these fibers are essentially completely biodegradable and disappear from the base layer. This activation threshold, from which degradability of the reinforcement fibers is given, can involve various physical effects. For example, a certain temperature can form this activation threshold. However, a specific humidity or concentration of water or other liquids in the vicinity of the reinforcement fibers can also form this activation threshold. In addition, other physical effects (such as irradiation with radiation of a certain wavelength, for example UV radiation) as an activation threshold for the biodegradability of the reinforcing fibers of a base layer also belong to the invention.

The biological degradation is initiated by the activation, in particular the molecules of the plastic are decomposed and then, under certain circumstances, further biological degradation or other decomposition or reshaping of the plastic takes place. The activation threshold is usually described by a chemical or physical parameter.

Furthermore, it is possible for the activation threshold to be formed by a combination of two or more physical and/or chemical effects. For example, the activation threshold can consist of a combination of a specific temperature and a specific water content in the vicinity of the reinforcement fibers. Exceeding such a combined activation threshold, formed from a temperature and a water content, leads then first to an absorption of water in the reinforcement fibers. This water absorption causes the molecules of the plastic that make up the reinforcement fibers to split. The further decomposition of the fission products then takes place by other mechanisms. The further decomposition can take place, for example, by saprobionts. These are organisms that feed on dead material and break it down, reshape it and crush it.

This decomposition can take place within the organisms, or by enzymes that the organisms release to the outside. Saprobionts are typical organisms in composting processes. Saprobionts in the form of thermophilic bacteria and fungi have proven to be particularly favorable for biological degradation of reinforcing fibers according to the invention. Such thermophilic creatures are particularly active at elevated temperatures, for example between 45 and 80 °C. However, complete biological degradation of the reinforcement fibers is not limited to degradation by thermophilic organisms. Other microorganisms are also suitable for this purpose, such as those found or used in composting. It is clear that biodegradation, as described, naturally also occurs when an activation threshold is exceeded, which is only defined by a temperature or only by another physical or chemical parameter.

Ultimately, after biological degradation, only organic and mineral material remains, which can be applied or distributed in nature without hesitation. A base layer according to the invention thus offers the very advantageous combination of high-quality stabilization function when used in hybrid sports turf with significantly simplified and improved disposal after use in hybrid turf.

It is particularly advantageous to select or set an activation threshold for the reinforcement fibers which, if possible, is never reached when used in the base layer of a hybrid turf in use. This ensures that no biological degradation of the reinforcement fibers takes place during use in the hybrid turf. When disposing of a used base layer, care is then taken to ensure that the activation threshold is deliberately and clearly exceeded, so that the then desired biological degradation of the reinforcement fibers can take place. After a certain time under conditions beyond the activation threshold, the base layer no longer has any plastic content and can be disposed of or reused at will.

It is cleverly provided that the activation threshold is a temperature higher than 50°C, 55°C, 60°C, 65°C or 70°C. According to the invention, the activation threshold, from which biological degradation of the reinforcement fibers takes place, is formed by a temperature which is higher than 50°C. This activation threshold can then be 55° C., for example. There are suitable plastics, such as polylactides (PLA), which absorb water molecules to a significant extent from this temperature, which in turn leads to the decomposition and thus the biological degradation of the plastics. In addition to exceeding the activation threshold formed here by a temperature, it should also be ensured that there is a sufficient amount of water to achieve good biological degradation of the reinforcement fibers. It is of course possible to use different plastics as the material for the reinforcement fibres, in which case the activation threshold can also be formed by higher temperatures. One way to reach or exceed the activation threshold is to place a used, degraded base course in a composting facility. In industrial composting plants, temperatures of more than 60 °C are often used, since germs are effectively killed above this temperature. The conditions in such a composting plant are therefore also ideal for the degradation of the reinforcement fibers in a base layer according to the invention. The temperature prevailing in the composting plant is well above the activation threshold for biological degradation of the reinforcement fibers and thus ensures safe and rapid degradation of the fibers. In addition, in an example not according to the invention, an activation threshold can also be formed by lower temperatures, for example in the range of 40° C. or 45° C. The activation threshold depends on the material from which the reinforcement fibers are made and the mechanisms or organisms intended to be used in the degradation or decomposition. Cleverly, such activation thresholds are useful in areas of application that are not reached with normal use as a base layer for a lawn.

Furthermore, it is advantageously provided that the reinforcement fibers, when used as a base layer in the ground, are stable with respect to UV radiation or water, among other things. In this embodiment, the reinforcement fibers are designed in such a way that they are stable with respect to the environmental conditions prevailing during their use in the base layer. This includes that the reinforcement fibers are stable against UV radiation, which is contained in sunlight. This is particularly beneficial when parts of the reinforcement fibers protrude from the ground. If the reinforcement fibers are completely housed or enclosed in the ground and thus normally no UV radiation hits the fibers, this property can be dispensed with and UV light can be used for activation, for example. This resistance to UV radiation can be achieved, for example, by using a UV-resistant, activatable plastic or by adding pigments or by coating them with a UV-absorbing coating in the case of less stable plastics. It is also possible to color the reinforcement fibers green in order to make them inconspicuous within the natural grass. Furthermore, the reinforcement fibers are designed in such a way that they are insensitive to water. As lawns need to be watered regularly to ensure good natural grass growth, the reinforcing fibers are designed in such a way that they do not absorb water under normal conditions of use in hybrid grass. This prevents inadvertent decomposition or swelling with the associated change in the mechanical properties of the fibers.

Furthermore, it is provided that the reinforcement fibers consist of a material from the group of polyvinyl alcohols (PVA). The reinforcement fibers of the base layer are made of a material that is biologically degradable beyond the activation threshold. Therefore, various biocompatible plastics can be used as a material for the reinforcement fibers.

It is advantageously provided that the base layer also has quartz sand and/or natural sand and/or lava and/or topsoil and/or peat and/or natural cork in addition to the reinforcement fibers. The reinforcing fibers serve to strengthen and improve the shear strength of the base course. The higher this shear strength, the higher the possible intensity of use of the hybrid turf and the lower the maintenance effort and required regeneration time.

In addition to the reinforcement fibers, the base layer contains various other materials that provide the other required properties of the base layer. For example, the base layer must be well permeable to water to prevent the hybrid turf from being flooded in heavy rain. For this reason, drainage systems are often installed within the base layer to drain away water. Furthermore, the base layer has the task of ensuring that the hybrid turf remains flat, even with regular use. In one possible embodiment of the invention, the base layer contains quartz sand and/or natural sand as the largest component. The proportion of these sands is usually 60 - 80 percent by volume. Grain sizes between 0.02 mm and 4 mm have proven to be particularly favorable.

Furthermore, lava can be a component of the base course. Lava is usually added to the base course in a proportion of 0 - 18 percent by volume (volume %).

An interval is specified for the proportion of lava, which is described by an upper and lower limit. The following values are provided as the upper limit, for example: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22 or 25% by volume. The following values, for example, apply as the lower limit: 0.5, 1, 1.5, 2, 4, 6, 8, 10 or 12% by volume. The disclosure of this application includes the set of all intervals, which consists of all possible, technically correct combinations of the aforementioned upper and lower limits.

Here, too, lava grain sizes between 0.02 mm and 4 mm have proven to be particularly favorable.

An interval is specified for the grain size of the lava, which is described by an upper and lower limit. The following values are provided as the upper limit, for example: 1, 1.5, 2, 2.5, 3, 3.5, 4, 5 or 6 mm. For example, the following values apply as the lower limit: 0.02, 0.05, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5, 0.7, 0.85, 1, 1.3, 1.5, 1.7, 2, 2.5, 3 or 4mm. The disclosure of this application includes the set of all intervals, which consists of all possible, technically correct combinations of the aforementioned upper and lower limits.

Another component of the base layer, in particular in a proportion of 5 - 20 percent by volume, is topsoil.

An interval is specified for the proportion of topsoil, which is described by an upper and lower limit. For example, there are as an upper limit the following values are provided: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 25, 28 or 30% by volume. The following values, for example, apply as the lower limit: 0.5, 1, 1.5, 2, 4, 6, 8, 10 or 12% by volume. The disclosure of this application includes the set of all intervals, which consists of all possible, technically correct combinations of the aforementioned upper and lower limits.

Suitable topsoil for a base layer is defined in the DIN 18300 standard as soil class 1 as topsoil or topsoil and contains humus and soil organisms in addition to inorganic material. Flowing soil types, as classified as soil group 2 in the DIN 18915 standard, are also suitable.

Another suitable component of the base layer is peat, ideally in a proportion of 3 - 11 percent by volume (volume %). Experience has shown that raised bog peat or fine white peat can be used.

An interval is specified for the proportion of peat, which is described by an upper and lower limit. The following values are provided as the upper limit, for example: 2, 4, 6, 8, 10, 11, 12 or 13% by volume. The following values, for example, apply as the lower limit: 0.5, 1, 1.5, 2, 4, 6 or 8% by volume. The disclosure of this application includes the set of all intervals, which consists of all possible, technically correct combinations of the aforementioned upper and lower limits.

Furthermore, a base layer of natural cork, in particular with a grain size between 0.5 mm and 20 mm, preferably between 3 mm and 7 mm, can be used.

An interval is specified for the grain size of natural cork, which is described by an upper and lower limit. The following values, for example, are provided as the upper limit: 3, 5, 7, 10, 12, 15, 17 or 20 mm. For example, the following values apply as the lower limit: 0.5, 1, 2, 3, 4, 5, 7, 10, 12 or 15 mm. The disclosure of this application includes the set of all intervals, which consists of all possible, technically correct combinations of the aforementioned upper and lower limits.

Depending on the desired properties of the hybrid turf, the proportion of natural cork can range from 0 - 13 percent by volume (volume %).

An interval is specified for the proportion of natural cork, which is described by an upper and lower limit. The following values are provided as the upper limit, for example: 2, 4, 6, 8, 10, 12 or 13% by volume. The following values, for example, apply as the lower limit: 0.5, 1, 1.5, 2, 4 or 6% by volume. The disclosure of this application includes the set of all intervals, which consists of all possible, technically correct combinations of the aforementioned upper and lower limits.

The components of a base layer listed here have proven to be particularly favorable in practice. Of course, however, other and further components can also be contained in the base layer. In addition, grain sizes or proportions by volume other than the stated sizes or proportions of the components in a base layer also belong to the invention and are disclosed.

Furthermore, it is advantageously provided that the layer thickness of the base layer is between 30 mm and 300 mm, in particular between 60 mm and 200 mm. The base layer can be of different thicknesses depending on where it is used and the desired properties of the hybrid turf. Thicknesses between 60 mm and 200 mm have proven particularly favorable. Thicknesses between 30 mm and 300 mm are also well suited. In addition, however, thinner or thicker base layers are also covered by the invention. An interval is specified for the layer thickness, which is described by an upper and lower limit. The following values are provided as the upper limit, for example: 150 mm, 200 mm, 250 mm and 300 mm. For example, the following values apply as the lower limit: 30 mm, 45 mm, 75 mm, 60 mm and 90 mm. The disclosure of this application encompasses the set of all intervals that consists of all possible combinations of the aforementioned upper and lower limits.

Furthermore, it is provided according to the invention that the proportion of reinforcement fibers in the base layer is between 0.1 and 4% by weight. The proportion of reinforcement fibers in the base layer is relevant to the shear strength of the base layer. A proportion of between 0.1 and 4% by weight of the reinforcement fibers in the base layer has proven to be particularly favorable for the shear strength.

An interval is given for the proportion of reinforcement fibers, which is described by an upper and lower limit. The following values are provided as an upper limit, for example: 2, 4, 6, 8 or 10% by weight. The following values, for example, apply as the lower limit: 0.05, 0.1, 0.5, 1, 1.5, 2 and 4% by weight. The disclosure of this application includes the set of all intervals, which consists of all possible, technically correct combinations of the aforementioned upper and lower limits.

It is advantageously provided that the length of the reinforcement fibers is between 15 mm and 700 mm, in particular between 30 mm and 500 mm. The length of the reinforcement fibers also influences the shear strength achieved in the base layer. When selecting a length for the reinforcement fibers, the way in which the fibers are introduced into the base course plays a role. If the fibers are mixed into the base layer before the hybrid turf is applied, other fiber lengths can be optimal than when the reinforcing fibers are added to an already laid lawn or a base layer that has already been laid. Particularly favorable results can be achieved with reinforcement fibers with a length between 30 mm and 500 mm. Good shear strength is also achieved in range between 15 mm and 700 mm achieved. In addition, however, larger or smaller lengths of the reinforcement fibers also belong to the invention. An interval is specified for the length of the reinforcement fibers, which is described by an upper and lower limit. The following values are provided as the upper limit, for example: 90 mm, 100 mm, 150 mm, 250 mm, 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, 550 mm, 600 mm, 650 mm and 700 mm. For example, the following values apply as the lower limit: 15 mm, 30 mm, 45 mm, 60 mm, 75 mm and 100 mm. The disclosure of this application includes the set of all intervals, which consists of all possible, technically meaningful combinations of the aforementioned upper and lower limits.

In a preferred embodiment of the proposal, the thickness of the reinforcement fibers is between 0.05 mm and 2 mm, in particular between 0.1 mm and 1 mm. The thickness of the reinforcement fibers also influences the mechanical strength of the base layer and thus of the hybrid turf. Particularly favorable results have been shown with a thickness of the reinforcement fibers between 0.1 mm and 1 mm. However, there are also very good results for the thickness of the reinforcement fibers in the range between 0.05 mm and 2 mm. In addition, larger or smaller thicknesses of the reinforcing fibers are also disclosed with the invention. An interval is given for the thickness of the reinforcement fibers, which is described by an upper and lower limit. The following values, for example, are provided as the upper limit: 1 mm, 1.5 mm, 2 mm, 2.5 mm and 3 mm. For example, the following values apply as the lower limit: 0.05 mm, 0.1 mm, 0.2 mm, 0.4 mm and 0.6 mm. The disclosure of this application includes the set of all intervals, which consists of all possible, technically meaningful combinations of the aforementioned upper and lower limits.

According to the invention, it is provided that the reinforcement fibers are distributed randomly in different directions within the base layer and that there is at least partial interlocking between the individual reinforcement fibers. In this embodiment of the invention, the reinforcement fibers are present in a disordered manner within the base layer. This means that there is no preferred or conscious direction in which the fibers run. Between the individual fibers present in a disorderly distribution, there is at least partial interlocking of the individual reinforcement fibers with one another. The fibers touch each other, hook into each other or are partially wrapped around each other. This creates an interaction between the individual fibers, which corresponds to a kind of cross-linking. This cross-linking or interlocking ensures the desired improvement in the shear strength of the base layer. Thanks to the improved shear strength, the hybrid turf can be used much more intensively without excessive wear and requires shorter regeneration times. Such a disordered presence of the reinforcement fibers in the base layer can be produced, for example, by mixing the reinforcement fibers with the other components of the base layer before the base layer is applied to the ground. The base layer, mixed with reinforcement fibers in this way, is then applied to the floor of the sports facility and laid out as the top layer of the natural turf. The random reinforcement fibers in the base layer have proven to be particularly beneficial for stabilizing the root zone of natural grass. Of course, it is also part of the invention that reinforcing fibers are subsequently introduced in a random direction into an already created turf structure.

A combination of different arrangements of the reinforcement fibers within the base layer is also possible. For example, random reinforcement fibers in the base layer can be used in combination with an ordered layer of fibers in order to create special properties of the hybrid turf. It is cleverly provided that the reinforcement fibers are present in the base layer in the form of a net or fabric. In this embodiment, reinforcement fibers are present in the support layer in an ordered form in the form of a net or fabric. Such an ordered shape provides a particularly good improvement in the shear strength of the base layer along the direction of the reinforcement fibers. It is possible here to arrange different net-like or fabric-like arrangements one on top of the other, with the direction of the fiber paths being slightly offset in each case. This in turn allows excellent shear strengths to be generated in different directions. Such net-like or fabric-like reinforcement fibers can be introduced into the base layer, for example, by first distributing a portion of the base layer on the ground, then placing the net-like reinforcement fibers on top and then adding more base layer material. The reinforcement fibers are designed, for example, as rolled goods or web goods and are rolled out on a base. This application of the base layer in layers can, of course, also be carried out with several layers of reinforcing fibers.

The object of the invention is also achieved by a method for processing a base layer according to claim 7 according to one of the described embodiments, comprising the method steps: activation of the reinforcement fibers, in particular composting of the base layer. A used base layer of a hybrid turf is prepared with the aid of the method according to the invention. The activation threshold of the reinforcement fibers is exceeded, as a result of which the reinforcement fibers are then biodegradable. The reinforcement fibers, which previously behaved stably when used in hybrid turf, are now completely broken down after activation, i.e. after exceeding the activation threshold, so that after a certain time they are no longer present in the base layer. Composting the used base layer has proven to be particularly favorable for activation or for exceeding the activation threshold. In the case of composting, in particular industrial composting, there are environmental conditions which can lead to the activation threshold being exceeded and thus to biological degradation of the reinforcement fibers in the base layer.

It is cleverly provided that the activation, in particular composting, takes place at temperatures higher than 50°C. In this embodiment of a method according to the invention, the reinforcement fibers are activated by temperatures higher than 50.degree. C., 55.degree. C., 60.degree. C., 65.degree. C. or 70.degree. These temperatures are reached particularly easily in the context of industrial composting, in which temperatures of this level or even higher are normal and common. Due to the fact that the activation temperatures in industrial composting plants are common, options for activating and thus breaking down the reinforcement fibers are easily and inexpensively accessible.

Furthermore, it is planned that the base layer is removed from the ground before activation/composting. In this embodiment of the method, the base layer is first removed from the floor of the sports facility and then fed to the activation or composting, where the degradation of the reinforcement fibers then takes place. This has the advantage that the base layer that has been removed can be immediately replaced with a new base layer to create a new hybrid turf, which means there is no downtime in the sports facilities.

It is advantageously provided that, after activation/composting, the base layer is used as biomaterial/soil, in particular for the construction of a base layer according to one of the embodiments already described. In this embodiment of the method, the material of the used base layer is used for the construction of a new base layer after the reinforcement fibers have been broken down. This has the advantage that the materials of the old base layer are already mixed with each other in a favorable ratio and therefore little or no effort is required when mixing a new base layer. New reinforcement fibers can then be added to the new base course in the appropriate amount, shape and form, as required, depending on the desired shear strength. In addition to using the material from the used base layer after the reinforcement fibers have been completely broken down for a new base layer, the processed material can also be used for other applications, for example in agriculture, horticulture or the like, since it is now free of plastics. Because the material is completely free of plastic residues, it can also be used in nature, for example to create biotopes or the like.

In this context, it is particularly pointed out that all the features and properties described in relation to the device, but also procedures, can also be transferred to the formulation of the method according to the invention and can be used in the sense of the invention and are also disclosed. The same also applies in the opposite direction, which means that structural features that are only mentioned in relation to the method, i.e. features according to the device, can also be taken into account and claimed within the scope of the device claims and also form part of the disclosure.

• Fig. 1 eine dreidimensionale, geschnittene Ansicht einer ersten Ausführungsform einer Tragschicht in einem Sportboden,
• Fig. 2 eine dreidimensionale, geschnittene Ansicht einer zweiten Ausführungsform einer erfindungsgemäßen Tragschicht in einem Sportboden und
• Fig. 3 eine dreidimensionale, geschnittene Ansicht einer dritten Ausführungsform einer Tragschicht in einem Sportboden.

In the drawing, the invention is shown schematically in particular in one embodiment. Show it:

• 1 a three-dimensional, sectional view of a first embodiment of a base layer in a sports floor,
• 2 a three-dimensional, sectional view of a second embodiment of a base layer according to the invention in a sports floor and
• 3 a three-dimensional, sectional view of a third embodiment of a base layer in a sports floor.

In the figures, elements that are the same or that correspond to one another are denoted by the same reference symbols and are therefore not described again unless this is expedient. The disclosures contained throughout the description can be transferred to the same parts with the same reference numbers or the same component designations. The position information selected in the description, such as top, bottom, side, etc., refers to the figure directly described and shown and must be transferred to the new position in the event of a change of position. Furthermore, individual features or combinations of features from the different exemplary embodiments shown and described can also represent independent, inventive solutions or solutions according to the invention.

1 shows a three-dimensional, sectional view of a first embodiment of a base layer in a sports floor. A sports floor is to be understood here as the entirety of all layers that form the subsoil for practicing sports. A hybrid turf has proven to be particularly favorable as a sports floor. A sports surface formed by a hybrid turf contains artificial fibers in at least one of its layers and otherwise has a natural structure. The basis of the sports floor shown is a floor 4. A floor 4 is to be understood here as any subsoil that naturally predominates or already exists at the point where the sports floor is laid out shall be. This floor 4 is leveled before the construction of the sports floor and, if necessary, otherwise pretreated, for example compacted, so that it forms a good subsoil for the base layer 1 that follows.

The base layer 1 is located, as in 1 can be seen on the ground 4. Above the supporting layer, in turn, is the turf 3. The turf 3 is normally formed by a natural turf. However, it would also be possible to produce the sports floor shown with a turf 3, with the turf 3 being formed by an artificial turf. Turf 3 is thus to be understood as meaning the area in which the blades of a natural or artificial turf protrude from the base layer 1 . The roots of a turf 3 formed by natural turf are located, at least for the most part, within the base layer 1. In the area of the turf 3, the athletes come into direct contact with the sports ground. Essential for the function of the shown sports floor and the base layer 1 are the reinforcement fibers 2, which are 1 illustrated embodiment of a base layer run substantially vertically. The ends of the reinforcement fibers 2 protrude from the base layer 1 upwards into or through the turf 3. This protrusion of the reinforcement fibers 2 into or through the turf 3 ensures additional reinforcement and thus more intensive usability of the turf 3. Within the base layer 1, the reinforcement fibers 2 also provide reinforcement, which leads to improved shear strength of the entire sports floor. In the embodiment shown, the reinforcement fibers 2 were subsequently implanted from above into the base layer 1 after the base layer 1 and the turf 3 had been applied to the ground 4 . This can be done by hand or with the aid of a device or machine. In the case shown, the reinforcement fibers 2 were picked up by a tool approximately in the middle of their length and then pushed through the turf 3 into the base layer 1 in a vertical direction. Of course, it is also possible to push the reinforcement fibers 2 into the base layer first and then apply the turf 3 . In addition, the reinforcement fibers 2 can also be introduced into the base layer 1 by other methods or with other aids in such a way that, as in the case shown, they run essentially in the vertical direction.

2 shows a three-dimensional, sectional view of a second embodiment of a base layer according to the invention in a sports floor. The construction of the sports floor, which in 2 shown consists of the same layers as shown in 1 have already been described. The reinforcement fibers 2 are in the 2 shown embodiment of the base layer 1 disordered and running in different directions. Due to the fact that the reinforcement fibers are disordered and run in spatial directions that change along the course of the fibres, the reinforcement fibers 2 interlock or interlock with one another Shear strength of the base layer 1 and thus the entire sports floor leads. Furthermore, randomly running reinforcement fibers 2 stabilize the root zone of the turf 3 and thereby ensure increased wear resistance of the sports floor. Also in the 2 illustrated embodiment, the ends of the reinforcement fibers 2 can protrude out of the base layer 1 and up into or through the lawn 3 . This in turn leads to increased wear resistance and better playability of the turf 3, which is thereby formed both from natural blades of grass and from synthetic reinforcing fibers 2, which is often referred to as a hybrid turf. For a more pleasing look, the reinforcement fibers 2 can be colored green so that they can hardly be distinguished from the appearance of the natural blades of grass. The insertion of the reinforcement fibers in the in 2 The illustrated embodiment of a base layer is advantageously carried out before the base layer 1 is applied. The reinforcement fibers 2 can be evenly mixed with the other materials of the base layer 1 before the sports floor is constructed. This then saves time when setting up the sports floor at the sports facility. Of course, it is also possible to apply or mix in the reinforcement fibers 2 while the base layer 1 is being applied to the floor 4 . In addition, the reinforcement fibers 2 can also be introduced into the base layer 1 after the turf 3 has been applied.

In addition, the in 1 and 2 illustrated embodiments of a base layer can also be combined with one another, so that both disordered and ordered introduced reinforcement fibers 2 are present in a base layer 1.

3 shows a three-dimensional, sectional view of a third embodiment of a base layer in a sports floor. Also in this 3 shown embodiment of a base layer 1, the layer structure is identical to 1 and 2 . In the illustrated embodiment, the reinforcement fibers 2 are in the form of a type of fabric or mesh. This means that the fibers are regularly arranged in a certain way. In the case shown, the fibers run essentially horizontally and either parallel to one another or they form a 90° angle to one another. This arrangement of the reinforcement fibers ensures particularly good strengthening of the base layer in the direction of the reinforcement fibers 2. Since the reinforcement fibers 2 in 3 shown embodiment essentially only in two horizontal directions, which are rotated 90 ° to each other, the strength of the base layer 1 is particularly high in these directions, but lower in other directions. Therefore, several fabrics or meshes made of reinforcement fibers can also be used 2, which are twisted relative to each other with respect to the fiber direction, are introduced into the base layer 1. So that the base layer 1 is strengthened in other directions. The introduction of a net or fabric made of reinforcement fibers 2 can take place particularly favorably during the application of the base layer 1 to the floor 4 . It is also possible parallel to that 3 shown a net or fabric made of reinforcement fibers 2 to provide further such nets or fabrics, one of which can also be provided at the border between the base layer 1 and the lawn 3 . A net or fabric made of reinforcement fibers 2 directly at the border to the turf 3 strengthens the root zone of the turf 3, which in turn increases the wear resistance of the sports floor. Also the in 3 The illustrated embodiment of a base layer 1 can be combined with one or both of the embodiments shown in 1 and 2 shown are used in combination.

Claims (8)

1. Support layer for turf with reinforcing fibres (2) of plastic, wherein these reinforcing fibres (2) are essentially not biodegradable under environmental conditions when used as support layer in the soil, characterized in that within the support layer (1) the reinforcing fibres (2) are distributed disorderedly in different directions, and there is at least a partial interlocking of the single reinforcing fibres (2), wherein the amount of the reinforcing fibres (2) in the support layer is between 0.1 and 4 % by weight, and these reinforcing fibres (2) have an activation threshold above which the reinforcing fibres (2) are essentially completely biodegradable, wherein the activation threshold is a temperature above 50° C, characterized in that the reinforcing fibres (2) consist of a material of the group polyvinyl alcohols (PVA).
2. Support layer according to Claim 1, characterized in that the reinforcing fibres (2) are resistant, among others, to UV radiation or water when used as support layer in the soil.
3. Support layer according to any one of the preceding claims, characterized in that the support layer is provided, besides the reinforcing fibres (2), also with quartz sand and/or natural sand and/or lava and/or topsoil and/or peat and/or natural cork.
4. Support layer according to any one of the preceding claims, characterized in that the layer thickness of the support layer is between 30 mm and 300 mm, in particular between 60 mm and 200 mm.
5. Support layer according to any one of the preceding claims, characterized in that the length of the reinforcing fibres (2) is between 15 mm and 700 mm, in particular between 30 mm and 500 mm.
6. Support layer according to any one of the preceding claims, characterized in that the thickness of the reinforcing fibres (2) is between 0.05 mm and 2 mm, in particular between 0.1 mm and 1 mm.
7. Method for treating a support layer according to any one of the preceding claims, comprising the method steps

   - Removal of the support layer (1) from the soil (4),

   - Activation of the reinforcing fibres (2), in particular composting the support layer (1),
   wherein the activation, in particular composting is carried out with a temperature higher than 50°C.
8. Method according to Claim 8, characterized in that after the activation/composting the support layer (1) is used as bio material/soil, in particular for the construction of a support layer (1) according to any one of Claims 1 to 7.

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