Paving stone, paving and use of a paving

Abstract

 Paving stone (1) with a top surface (2) and a bottom surface (3) and at least three side faces (4, 5, 6, 7) extending from the top surface to the bottom surface, whereby the paving stone (1) is provided with a first connecting cavity (8) that forms a connection between a first side face (4) and a second side face (5) and with a second connecting cavity (11) that forms a connection between a third side face (4) and another side face (4, 5, 7), whereby the first and second connecting cavities (11) are connected together, whereby the transverse cross-section of both the first connecting cavity (8) and the second connecting cavity (11) is at least 5% of the area of the smallest of the side faces (4, 5, 6, 7) that are connected by this connecting cavity (8, 11).

Description

[0001] The present invention relates to a paving stone, a paving and the use of a paving.

[0002] More specifically the invention concerns a paving around trees and any other plants. The problem arises here is that tree roots need air, such that if sufficient air cannot get into the ground, they will grow very shallowly, just below the paving. As a result, the tree roots can push the paving upwards, which can lead to an uneven paving and even to damage.

[0003] Thus for the laying of paving, increasing attention is being paid to sufficient aeration for the roots. For example it is known to put aeration pipes in the ground between the roots.

[0004] It goes without saying that this can only be done optimally if the tree still has to be planted, and entirely new paving has to be laid. However this is difficult to do with existing trees, for example, when existing paving has to be renewed.

[0005] It is also known, when laying paving, to place hollow plastic shells that can be connected together on a support on the subsoil that is intended for the roots, provided with a reinforcement and poured over with concrete. For example this is the 'Watershell' system of Waterblock.

[0006] As a result a large plate of reinforced concrete is formed on site that is provided with an aeration network defined by the plastic shells.

[0007] However, this method requires a lot of work and is thus expensive, because the plastic shells must be placed accurately on supports to prevent the concrete plate breaking later on and to prevent the connection between two plastic shells not being made, such that the concrete can fill the space provided for air channels, and because many steps are required.

[0008] The plastic shells themselves can be expensive and are lost when they are poured over with concrete.

[0009] A further disadvantage is that this method is not flexible, because large areas must be laid in one go and because side formwork has to be provided.

[0010] A problem also arises of course when, after laying, underground works are needed that require the paving to be removed locally, because the concrete plate will then be damaged by them and it is not easy to repair.

[0011] Such a network also forms an impenetrable surface for water and air due to the plastic shells connected together, so that a specially provided air inlet is required in order to bring air into the aeration network and supplementary water drainage means must be provided around the concrete plates to prevent flooding.

[0012] The purpose of the present invention is to provide a solution to the aforementioned and other disadvantages, by providing a paving stone preferably made of concrete, in particular porous concrete, with a top surface and a bottom surface and three or more side faces extending from the top surface to the bottom surface, whereby the paving stone is provided with a first connecting cavity that forms a connection between a first side face and a second side face and with a second connecting cavity that forms a connection between a third side face and another side face, whereby the first connecting cavity and the second connecting cavity are connected together, whereby the smallest area, in the transverse cross-section, of both the first connecting cavity and the second connecting cavity is at least a certain percentage of the area of the smallest of the side faces that are connected by the respective connecting cavity, whereby the specified percentage is 5%.

[0013] Such a paving stone enables a paving with a network of connected air channels, formed by the connecting cavities, to be formed whereby, thanks to the minimum dimensions of the connecting cavities, sufficient airflow and thereby aeration of the roots of a tree is possible.

[0014] As a result the roots have no tendency or less of a tendency to develop just below the surface, so that the paving will not be damaged by the roots.

[0015] Here the 'transverse cross-section' is the cross-section perpendicular to the direction in which the connecting cavity concerned extends. Because this direction is normally horizontal, the transverse cross-section is normally a vertical cross-section.

[0016] Hereby the side faces are seen as straight surfaces that extend between the top surface and bottom surface, and which are generally perpendicular to the top and bottom surface. These side faces are thus the transition between a paving stone and an identical paving stone placed next to it.

[0017] However, on account of the connecting cavities, the physical surface of the sides of the paving stone can be absent locally or curved inwards locally and thus differs from the accompanying side face.

[0018] The paving stone can be used as a top paving stone of a paving, whereby the top surface of the paving stone forms the surface of the paving, but can also be used in an underlying layer, where another layer can be laid on top, for example standard clinkers or asphalt.

[0019] In a preferred embodiment, the specified percentage is 10%, more preferably 15%, and even more preferably 19%, whereby the air circulation is successively better.

[0020] In a further preferred embodiment the paving stone has four side faces, whereby the second connecting cavity forms a connection between the third and fourth side face and whereby the first and second side face are opposite one another and the third and fourth side face are opposite one another.

[0021] Such a paving stone is easy to make and lay.

[0022] In another preferred embodiment the paving stone is entirely or partially made of porous concrete. As a result the outside air and water can easily reach the connecting cavities and also easily get to the roots from the connecting cavities.

[0023] In a further preferred embodiment the paving stone comprises a third connecting cavity that connects the bottom surface with the other connecting cavities, whereby the smallest area of the third connecting cavity, in a cross-section parallel to the bottom surface, is at least the specified percentage of the area of the bottom surface.

[0024] This enables air in the first and second connecting cavities to get to the subsoil and thus to the roots of a tree via the third connecting cavity.

[0025] This has the advantage that, if roots develop to any extent just below a paving formed of such paving stones, the subsoil thereby pushed upwards is pushed into the combined connecting cavities via the third connecting cavity and can stay there without the paving stone itself being pushed upwards.

[0026] In a preferred embodiment of the first connecting cavity is constructed as a recess in the third side face.

[0027] In other words this means that the third side face is partially deepened, thus that a deepening is made in the third side face, and this deepening forms the first connecting cavity. Hence this deepening extends over the entire length or width of this third side face, thus from the first side face to the second side face.

[0028] Alternatively this preferred embodiment can be described as follows: the first connecting cavity is constructed as a preferably horizontal groove in the third side face, whereby this groove runs from the first side face to the second side face.

[0029] It goes without saying that this recess, groove or deepening cannot be so deep that it continues to the fourth side face, as then the paving stone would be entirely cut through horizontally.

[0030] In another preferred embodiment the third connecting cavity is constructed as a recess in the third or fourth side face.

[0031] In other words this means that the third or fourth side face is partially deepened and that a deepening is thus made in the third or fourth side face, whereby this deepening runs from the bottom surface to one or both other connecting cavities.

[0032] Alternatively this preferred embodiment can be described as follows: the third connecting cavity is constructed as a groove in the third side face or fourth side face, whereby this groove runs from the bottom surface to the first and/or second connecting cavity.

[0033] In both last-mentioned preferred embodiments the paving stone is easy to manufacture in a mould, because there are no parts of the paving stone that could surround a part of the mould in such a way that the removal of the paving stone from the mould would be impeded.

[0034] In a preferred embodiment the first connecting cavity does not connect to the bottom surface, at least at the location of the edge formed by the third side face and the first side face, and at the location of the edge formed by the third side face and the second side face, and preferably as a whole.

[0035] In another preferred embodiment the second connecting cavity is constructed as a passage in the fourth side face, whereby this passage does not run to an edge of the fourth side face with another side face or with the top surface or the bottom surface.

[0036] These two last-mentioned embodiments enable the bottom surface to be constructed with a maximum size, such that a force exerted on it is distributed as well as possible over the subsoil and the risk of the paving stone sinking after laying is reduced.

[0037] This is important because such paving stones cannot be placed on a thick and hard reinforcing layer, because such a reinforcing layer would form a barrier to the aeration of the subsoil.

[0038] In a further preferred embodiment the distance from the first connecting cavity to the top surface is greater than to the bottom surface.

[0039] With paving stones that are placed next to one another in a paving, the area with which they rest against one another directly next to the top surface determines the strength of the paving because this area determines what forces, directly or by means of a joint, can be transferred to the rest of the paving.

[0040] Thanks to this preferred embodiment, this critical area is increased, which leads to a paving that is more stable.

[0041] In a further preferred embodiment the first and/or second connecting cavity is elliptical or semi-elliptical in a vertical cross-section. As a result an optimum balance between the vertical strength of the paving stone and the passage opening of the cavity is obtained.

[0042] The invention further concerns a paving that is entirely or partially formed by paving stones according to the invention and which comprises a network of horizontally extending air channels below street level for the supply of air at atmospheric pressure in the first and second connecting cavities of these paving stones, whereby the air channels are at least partially formed by the first and second connecting cavities of the paving stones.

[0043] Preferably the paving is hereby provided with an air passage that runs from connecting cavities, that are fitted together, of the said paving stones to the outside air. The air passage is hereby a deliberately placed tubular element that leads from the air channels to the outside air.

[0044] Such a paving enables a good air supply to tree roots below the paving in a cheap and easy way.

[0045] In a preferred embodiment the first connecting cavity of the paving stones is constructed as a recess in the third side face, whereby the paving stones are placed in pairs with their third side face towards one another so that the first connecting cavities of a pair of paving stones together form a continuous section of an air channel from the first side face to the second side face of the paving stones.

[0046] Such a pair of paving stones is hereby placed with its fourth side faces towards the fourth side faces of similar other pairs of paving stones.

[0047] If the paving is porous to water, it also acts as a buffering paving that enables water to be temporarily stored below the street surface in the connecting cavities until the subsoil can absorb this water.

[0048] Problems with water drainage in the event of heavy rainfall can be prevented in this way.

[0049] The connecting cavities can also be deliberately filled with fertilisers or water via the air inlet, for example in dry periods to prevent trees drying out. Hereby the person who does this can work quickly, because the speed of the water supply is not limited by the absorption speed of the subsoil.

[0050] The invention further concerns the use of the above-mentioned paving above the root zone of a tree for aerating the ground below the paving, in which the tree roots grow, via the air channels.

[0051] In other words, this is a method to provide the ground under a paving, and thereby tree roots that grow in this ground, with air by constructing the paving as a paving according to the invention.

[0052] The purpose here is to achieve a good air supply to the roots of the tree.

[0053] With the intention of better showing the characteristics of the invention, a preferred embodiment of a paving stone and paving according to the invention is described hereinafter by way of an example, without any limiting nature, with reference to the accompanying drawings, wherein:

Figure 1 schematically shows a perspective view of a paving stone according to the invention;

figure 2 schematically shows a perspective view of the paving stone of figure 1 from a different angle;

figure 3 shows a paving in which use is made of the paving stone of figure 1;

figure 4 shows a cross-section according to IV-IV of a part of the paving of figure 3; and

figure 5 shows a component necessary for the manufacture of the paving stone of figure 1.

[0054] The paving stone 1 shown in figures 1 and 2 is made of concrete, in this example non-porous concrete, although a construction of porous concrete or other inert materials is also possible.

[0055] The paving stone 1 has a height H of 22 cm, a length L of 22 cm and a width B of 11 cm, and consists of a top surface 2, a bottom surface 3 parallel to it and four side faces that are perpendicular to the top surface.

[0056] More specifically this concerns a first side face 4 and a second side face 5, that are parallel to one another, and a third side face 6 and fourth side face 7 that are also parallel to one another, whereby the third side face 6 is perpendicular to the first side face 4.

[0057] Hereby it is noted that the side faces 4, 5, 6 and 7 are straight side faces that have to be distinguished from the physical surfaces on the sides of the paving stone 1, that have a complex shape on account of the presence of cavities.

[0058] A number of cavities are made in the paving stone 1.

[0059] This concerns in particular a first connecting cavity 8, that connects the first and second side face 4,5 together and is parallel to the top surface 2. This first connecting cavity 8 has the shape of a semi-cylindrical groove that is made in the third side face 6, whereby the diameter D of the of the hypothetical complete cylinder of which the groove forms part is, in this example but not necessarily, 11 cm.

[0060] As a result the area in the transverse cross-section of the first connecting cavity 8, thus the passage opening of the first connecting cavity 8, forms approximately 19.6% of the area of both the first and the second side face 4,5.

[0061] The first connecting cavity 8 has a distance A₁ of 8 cm from the top surface 2 and a distance A₂ of 3 cm to the bottom surface 3.

[0062] The surface 9 that coincides with the third side face 6 and which connects to the top surface 2, i.e. the surface above the first connecting cavity 4, is thereby substantially larger than the surface 10 below the first connecting cavity 4.

[0063] The paving stone also has a second connecting cavity 11. This is made centrally in the fourth side face 7 and runs parallel to the top surface 2 up to the third side face 6, and thereby connects the third and fourth side face 6,7.

[0064] The second connecting cavity 11 is perpendicular to the first connecting cavity 8, and largely runs into the first connecting cavity 8, such that the first and second connecting cavities 8, 11 are connected together.

[0065] The second connecting cavity 11 has the shape of a cylinder, in this example but not necessarily elliptical, with the long axis A_V of the ellipse in the vertical orientation. This long axis A_V hereby has a length of 15 cm and the short axis A_H of the cylinder hereby has a length of 11 cm.

[0066] As a result, the area in the transverse cross-section of the second connecting cavity 11, thus the passage opening of the second connecting cavity 11, forms approximately 26.8% of the area of both the third and fourth side face 6,7.

[0067] Furthermore, the paving stone 1 has a third connecting cavity 12, that connects the bottom surface 3 to the first connecting cavity 8, and as a result also to the second connecting cavity 11 and all four side faces 4,5,6,7.

[0068] This third connecting cavity 12 has the shape of a semi-cylindrical groove that is made in the third side face 6, whereby the diameter D of the hypothetical complete cylinder of which the groove forms part is, in this example but not necessarily, 11 cm.

[0069] As a result the area in the horizontal cross-section of the third connecting cavity 12, thus the passage opening of the third connecting cavity 12, is approximately 19.6% of the area of the bottom surface 3.

[0070] The use of the paving stone 1 in a paving 13 is simple and as follows, as explained on the basis of figures 3 and 4.

[0071] This concerns a paving 13 around a tree 14, and then especially above the root zone of the tree 14, i.e. the zone in which the roots 15 of the tree 14 are intended to grow.

[0072] The subsoil of the paving 3 hereby consists of a tree substrate 16 that, depending on the needs, can be compacted with lava for example, so that a stable subsoil occurs.

[0073] From bottom to top the paving 13 is constructed of a layer of geotextile 17, a layer of demolition sand 18, a layer of paving stones 1 as described above, another layer of geotextile 17, another layer of demolition sand 18 and a metalling layer of traditional concrete clinkers 19. Other types of metalling such as tiles, asphalt, natural stone, etc., are also possible.

[0074] The paving stones 1 according to the invention are hereby placed in pairs with their third side faces 6 turned towards one another, whereby for the rest a line arrangement is maintained in the laying of the paving stones 1, so that the first connecting cavities 8 of paving stones 1 located next to one another fit together and the second connecting cavities 11 of paving stones 1 located next to one another fit together so that a continuous network of air channels is formed that extends in two directions.

[0075] There is joint sand between the concrete clinkers 19 that ensures that a good transmission of horizontal forces to adjacent concrete clinkers 19 can take place so that the concrete clinkers 19 are stable.

[0076] In order to guarantee a sufficient air supply to this network, a hose is provided that runs from the network to the outside air and which forms an air passage 20.

[0077] Air will now come into the air channels formed by the first and second connecting cavities 8, 11 via the air passage 20, and from there penetrate into the subsoil 16 via the third connecting cavities 12, so that the roots 15 of the tree 14 have sufficient air and will not grow excessively closely under the paving.

[0078] In times of drought, water can of course also be put in the network of channels through the same air passage 20, which can then slowly sink in the ground, thereby providing the tree 14 with sufficient water.

[0079] In order to prevent water spreading into the surrounds, and possibly even its unwanted drainage away, it is desirable to close the network of channels at a certain distance from the tree 14, for example by other paving stones or by edge stones.

[0080] In the above paving, the paving stones 1 according to the invention are used as a foundation layer for the rest of the paving 13. However, these paving stones 1 can also act as the top layer itself.

[0081] The paving stone 1 can be made in a mould 21 as shown in figure 5, by filling it with concrete and compacting it if necessary. When the concrete has sufficient strength, the not yet completely hardened paving stone 1 can be taken out of the mould 21 to harden further.

[0082] The mould 21 is provided with protruding parts 22 that correspond to the various connecting cavities 8.

[0083] In this way the paving stone 1 is made with its fourth side face 7 oriented upwards in the first instance.

[0084] It goes without saying that other manufacturing methods are also possible.

[0085] It is also possible to make the paving stone from other materials, such as silica stone or baked clay for example.

[0086] The present invention is by no means limited to the embodiment described as an example and shown in the drawings, but a paving stone and a paving according to the invention can be realised in all kinds of forms and dimensions, without departing from the scope of the invention.

Claims

1. Paving stone (1) with a top surface (2) and a bottom surface (3) and three or more side faces (4, 5, 6, 7) extending from the top surface to the bottom surface, whereby the paving stone (1) is provided with a first connecting cavity (8) that forms a connection between a first side face (4) and a second side face (5) and with a second connecting cavity (11) that forms a connection between a third side face (4) and another side face (4, 5, 7), whereby the first connecting cavity (1) and the second connecting cavity (11) are connected together, whereby the smallest area, in the transverse cross-section, of both the first connecting cavity (8) and the second connecting cavity (11) is at least a certain percentage of the area of the smallest of the side faces (4, 5, 6, 7) that are connected by the respective connecting cavity (8, 11), whereby the specified percentage is 5%.

2. Paving stone according to claim 1, characterised in that the first connecting cavity (8) is constructed as a recess in the third side face (6).

3. Paving stone according to any one of the previous claims, characterised in that the first connecting cavity (8) is constructed as a groove in the third side face (6), whereby this groove runs from the first side face (4) to the second side face (5).

4. Paving stone according to claim 2 or 3, characterised in that the first connecting cavity (8), at least at the location of the edge formed by the third side face (6) and the first side face (4) and at the location of the edge formed by the third side face (6) and the second side face (5) does not connect to the bottom surface (3).

5. Paving stone according to any one of the claims 2 to 4, characterised in that the distance (A₁) from the first connecting cavity (8) to the top surface (2) is greater than the distance (A₂) from the first connecting cavity (8) to the bottom surface (3).

6. Paving stone according to any one of the previous claims, characterised in that it has four side faces (4, 5, 6, 7), whereby the second connecting cavity (11) forms a connection between the third side face (6) and the fourth side face (7), and whereby the first side face (4) and second side face (5) are opposite one another and the third side face (6) and fourth side face (7) are opposite one another.

7. Paving stone according to claim 6, characterised in that the second connecting cavity (11) is constructed as a passage in the fourth side face (7), whereby this passage does not run up to an edge of the fourth side face (7) with another side face (4, 5, 6) or with the top surface (2) or with the bottom surface (3).

8. Paving stone according to any one of the previous claims, characterised in that it comprises a third connecting cavity (12) that connects the bottom surface (3) to the other connecting cavities (8,11), whereby the smallest area of the third connecting cavity (12), in a cross-section parallel to the bottom surface (3), is at least the specified percentage of the area of the bottom surface (3), whereby the third connecting cavity (12) is constructed as an essentially vertical continuous groove in the third side face (6) or fourth side face (7), whereby this groove runs from the bottom surface (2) to the first connecting cavity (8) and/or to the second connecting cavity (11).

9. Paving stone according to any one of the previous claims, characterised in that in a vertical cross-section the first connecting cavity (8) has the shape of a semi-ellipse, whereby this semi-ellipse is a vertically transected full ellipse, and/or the second connecting cavity (11) is elliptical in a vertical cross-section.

10. Paving (13) that is entirely or partially formed by paving stones (1) according to any one of the previous claims, and which comprises a network of horizontally extending air channels below street level for the provision of air in the first and second connecting cavities (8,11), whereby the air channels are at least partly formed by the first and second connecting cavities (8,11) of the paving stones (1).

11. Paving according to claim 12, characterised in that the air channels connect the first and/or second connecting cavity (8,11) of the paving stones to the outside air.

12. Paving according to claim 11, characterised in that it is provided with an air passage (20) that runs from connecting cavities (8, 11), that are fitted together, of the said paving stones (1) to the outside air.

13. Paving according to claim 12, characterised in that the paving stones are paving stones according to any one of the claims 2 to 4 whereby these paving stones are placed in pairs with their third side face (6) turned towards one another so that the first connecting cavities (8) of a pair together form a section of an air channel running from the first side face (4) to the second side face (5).

14. Paving according to any one of the claims 10 to 13, characterised in that the said paving stones (1) are placed in such an arrangement that the first connecting cavities (8) of adjacent paving stones (1) fit together in a first direction and the second connecting cavities (11) of adjacent paving stones (1) fit together in a second direction.

15. Use of a paving (1) according to any one of the claims 10 to 14 above the root zone of a tree for aerating the ground under the paving (14) via the air channels.

Drawing