"SUBSTRATE FOR SYNTHE TIC TURF"

[0001] This invention relates to a draining and shock- absorbing substrate for sports fields with synthetic turf.

[0002] As is known, a synthetic turf sports field comprises a synthetic turf surface formed by a mat to which the synthetic blades of grass are fixed. The grass blades are supported by an infill based on rubber granules placed over the mat. In some embodiments, the mat is in turn supported on a pad made of elastomeric material having draining and shock-absorbing properties.

[0003] In some embodiments, the pad is formed from multiple strips placed side-by-side that extend for example along the entire width of the sports field. Each strip is unrolled from a starting roll. In order to be wound to form a roll, the pad must have a limited thickness at the expense of the shock-absorbing effect. In these cases, it becomes necessary to increase the height of the infill based on rubber granules that is placed over the pad.

[0004] In addition, the weight and size of the roll requires machinery for its movement.

[0005] A further drawback of this pad is that the high temperature variations to which it may be subjected causes significant dimensional variations of the pad itself, which are propagated for its entire extension and that cause deformations of the grid markers of the playing field and the formation of humps.

[0006] In other embodiments, the pad is made by pouring the elastomeric material directly on the site. This embodiment, in addition to being limited to situations in which one must realise a permanent playing field, requires special equipment to be brought to the site where the pouring is to take place, long installation times and specialised labour.

[0007] An object of the invention is to propose a substrate having high draining and shock-absorbing characteristics and that is easy and quick to install and remove, for example to be recycled at its end of life.

[0008] Another object of the invention is to make available a substrate capable of compensating at least partially for deformations due to thermal variations, and suitable to be stored in a simple way and in small spaces.

[0009] Such objects are achieved by means of a substrate according to claim 1.

[0010] Further characteristics and advantages of the substrate according to the invention will be evident from the description given below of its embodiments, given by way of a non-limiting example with reference to the accompanying drawings, in which: [0011] - Figure 1 is a longitudinal sectional view of the substrate according to this invention, in correspondence of two adjacent plates, in a first embodiment;

[0012] - Figure la is an enlarged section of a detail of Figure 1, related to the coupling between the bosses of one plate and the recesses of a connection membrane;

[0013] - Figure 2 is a plan view from below of an assembled portion of substrate, in a first mode of use of the connection membrane;

[0014] - Figure 3 is a plan view from below of an assembled portion of substrate, in a second mode of use of the connection membrane;

[0015] - Figure 4 is a perspective view of the substrate according to the invention, in a second embodiment;

[0016] - Figure 5 is a longitudinal sectional view of the substrate of Figure 4, in correspondence of two adjacent plates; and

[0017] - Figure 5a is an enlarged section of a detail of Figure 5, related to the coupling between the cavities of one plate and the bosses of a connection membrane.

[0018] In said drawings (Figures 1 to 3), reference number 1 indicates, in its entirety, a draining and shock- absorbing substrate according to the invention, in a first embodiment, suitable to achieve horizontal drainage. [0019] "Horizontal drainage" means that, thanks to the characteristics of the substrate, which will be described below, and a slight "humpback" conformation of the ground, rainwater is made to flow toward the outer edges of the sports field.

[0020] The substrate 1 is constituted by a plurality of plates 10 and connection membranes 40 that act as connection means between adjacent plates 10.

[0021] The plates 10 are preferably all identical to each other and have for example a rectangular or square shape, for example of dimensions 120 cm x 80 cm.

[0022] The plates 10 are made from an elastomeric material such as SBR or NBR, for example deriving from ground tyres .

[0023] Each plate 10 has an upper side surface 12, suitable to receive a mat of a synthetic turf 5, and a bottom side with bosses 14, facing the ground. This bottom side 14 is defined by a lower base 15, parallel to the upper side surface 12 and defining a plate thickness dl, and a plurality of bosses 16 of equal height d2 that extend towards the ground from such lower base 15. These bosses indentations 16 thus form protrusions that stand out from the lower base 15. Each boss 16 terminates with one support end 18 on the ground (where the connection membrane 40 between the plates and the ground is not present) .

[0024] Preferably, the bosses 16 have a same height so as to form, with the ends 18, a support plane of the plate on the ground.

[0025] The bosses 16 can have a frusto-conical , hemispherical, frusto-pyramidal , or parallelepipedal shape, of circular or polygonal section.

[0026] The thickness dl of the plates can be between 2 cm and 3 cm.

[0027] The bosses 16 can have a maximum diameter of from 1 cm to 2 cm.

[0028] In a preferred embodiment, the bosses 16 are uniformly distributed on the entire surface of the lower base 15 of the plate.

[0029] In a preferred embodiment, the bosses 16 are arranged in parallel rows, and possibly staggered with each other, so that between one row and another a drainage channel 20 is formed for the outflow of rainwater that passes through the thickness of the plates towards the edges of the playing field.

[0030] Horizontal drainage is achieved by placing a waterproof sheet (not shown) between the plates 10 and the ground, so that rainwater that passes through the plates flows between the bosses and the waterproof sheet and, thanks to the slight inclination of the ground, it flows towards the edges of the playing field.

[0031] The connection membranes 40 have a shape complementary to the embossed side 14 and are suitable to be positioned between the plates 10 and the ground.

[0032] Each connection membrane 40 is formed of a membrane base 42 that goes in contact with the lower base 15 of the overlying plates, and a plurality of recesses 44 that extend downwards from said membrane base 42 and receive, with shape-coupling, the bosses 16 of the overlying plates.

[0033] Note that the recesses 44 of the connection membrane 40, when viewed from the side facing the soil, can also be considered bosses, but in this case hollow. The connection membrane 40 can therefore be defined an embossed membrane.

[0034] In particular, the connection membranes 40 are placed astride the adjacent sides of at least two adjacent plates 10 or in correspondence of the adjacent corners of four adjacent plates.

[0035] When placed astride at least two adjacent plates, or the plates of two adjacent rows of plates, the connection membranes 40 are in the form of a strip, for example a rectangular strip (Figure 2) .

[0036] When they are superimposed on the adjacent corners of four adjacent plates, the connection membranes 40 can have a square shape (Figure 3) .

[0037] For example, each connection membrane 40 has at least two rows of recesses 44 for two corresponding end rows of bosses of each plate. Therefore, a connection membrane 40 is provided with four rows of recesses 44.

[0038] Thanks to the connection membranes 40, ad acent plates are mutually connected to each other in a horizontal direction, i.e., in any direction parallel to the ground. Therefore, the plates connected by the connection membranes cannot mutually translate.

[0039] The planar extension of the connection membranes 40 should be sufficient to ensure a secure connection between adjacent plates, but not hamper the absorption of rainwater into the underlying soil and runoff towards the edges of the playing field through drainage channels 20 free from the connection membranes 40.

[0040] The thickness of the connection membranes can be, for example, between 0.6 mm and 1.20 mm. Preferably, this thickness should be selected so as to not significantly affect the overall thickness of the substrate and not reveal the step between the portions of substrate supported on the connection membranes and the portions of substrate resting directly on the ground.

[0041] In a preferred embodiment, for the embossed connection membrane 40, one can use embossed membranes already on the market and used in construction as impermeable, draining and ventilating barriers for realising raised floors, micro loose stone foundations and tunnels. These embossed membranes 40 are for example made of high density polyethylene (HDPE) , have a thickness of about 1 mm, frusto-conical bosses 44 having a height between 10 mm and 20 mm and a specific number of bosses per square meter, for example equal to about 400.

[0042] In the case of using these already commercially available embossed membranes, the shape of the embossed side 14 of the plates 10 is chosen so as to adapt to the shape of these membranes.

[0043] Figures 4 and 5 illustrate a substrate 1' in a variant embodiment, which in particular allows vertical drainage of water that passes through the thickness of the substrate. "Vertical drainage" means the water that is not guided to flow horizontally toward the edges of the sports field, but is retained in contact with the ground below the substrate to be absorbed by the ground. Naturally, this technical solution is chosen in the case of soil with high draining capacity or specially made.

[0044] This embodiment always provides for the use of a plurality of plates 100 and connection membranes 400 that act as connection means between adjacent plates 100.

[0045] The plates 100 are preferably all identical to each other and have a rectangular or square shape, for example of dimensions 120 cm x 80 cm.

[0046] The plates 100 are made from an elastomeric material such as SBR or NBR, for example deriving from ground tyres.

[0047] Each plate 100 has an upper side surface 120, suitable to receive a mat of a synthetic turf 5, and a bottom side 140, suitable to rest on the ground (where a connection membrane is not present) . This bottom side 140 is parallel to the upper side surface 12 and defines a plate thickness d4.

[0048] In the bottom side 140 is formed a plurality of cavities 160. These cavities 160 extend in the thickness of the plate, towards the upper side surface 120. These cavities 160 thus form the collection chambers of the water that penetrates from the upper side surface 120 and passes through the material of the plate 100.

[0049] The cavities 160 can have a frusto-conical , frusto- pyramidal, hemispherical or parallelepipedal shape, of circular or polygonal section.

[0050] In a preferred embodiment, the cavities 160 are evenly distributed all over the surface of the bottom side 140 of the plate 100.

[0051] In a preferred embodiment, the cavities 160 are arranged in rows staggered from each other, for example parallel to the edges of the plate.

[0052] Preferably, the cavities 160 do not communicate with each other, except through interstices that can form between the bottom side 140 of the plate and the ground. In other words, the openings 160' of the cavities 160 are isolated from each other by flat regions 140' of the bottom side 140 of the plate 100.

[0053] The connection membranes 400 have a shape complementary to the bottom side 140 and are suitable to be positioned between the plates 100 and the ground.

[0054] Each connection membrane 400 is formed of a membrane base 420 suitable to be interposed between the ground and the bottom side 140 of the overlying plates, and a plurality of bosses 440 that extend downwards from said membrane base 420 and that are received, with shape- coupling, in the cavities 160 of the overlying plates.

[0055] Note that, as connection membrane 400, it is possible to use the same connection membrane 40 described above for the case of horizontal drainage, but used in flipped, namely rotated by 180°.

[0056] In particular, also for the embodiment suitable for vertical drainage it is possible to use the embossed membranes 40 already used in civil engineering mentioned above .

[0057] The modes of coupling between the plates 100 and the connection membranes 400 are the same as those already described above for the substrate with horizontal drainage .

[0058] It is clear how the substrate proposed here allows achieving the predefined purposes.

[0059] The plates 10; 100, thanks to the elastomeric material and the thickness with which they are made, perform the desired function of creating a draining, elastic and shock-absorbing substrate that thus requires a lower usage of performance infill in the turf mat.

[0060] The laying of the plates and connection membranes is particularly quick and easy.

[0061] The realisation of the substrate in side-by-side plates allows eliminating or, in any case, reducing the effects of thermal expansion, thanks to the play between adjacent plates.

[0062] The plates and the connection membranes can be easily and quickly removed after use and are therefore particularly suitable for creating fields for sports exhibitions or occasional play.

[0063] The plates can be stored and transported in stacks one above the other. The connection membranes can also be stored and transported in stacks or cut on site.

[0064] To the embodiments of the draining and shock- absorbing substrate according to the invention, one skilled in the art, in order to meet specific needs, may make variants or substitutions of elements with others functionally equivalent.