WO2024245803A1 - Drainage slab and structure comprising such a drainage slab - Google Patents

Abstract

The invention relates to a prefabricated drainage slab intended for the production of a floor for a parking or rest area. The drainage slab comprises a raising element (5) for raising the drainage slab and a reinforcement (3) covering the support (3) so as to form a first face (1). The support part (3) is a material comprising particles of a plant material embedded in a mineral binder. The support is a porous material that has open pores and a first mass content of plant material particles of between 30% and 70%, the average length of the particles being between 10 mm and 100 mm. The support (3) has a higher compressive strength than the support (3). The reinforcement (4) is made of at least one porous material with open pores. The porosity of the reinforcement and of the support forming drainage channels (1).

Description

DRAINAGE SLAB AND CONSTRUCTION COMPRISING SUCH A DRAINAGE SLAB

The invention relates to a draining slab and to a construction comprising such a draining slab.

For parking motor vehicles, it is conventional to use parking areas made of concrete or other materials that are chosen to withstand the mass of the vehicle as well as the elements. However, the main disadvantage of concrete and asphalt is that they form impermeable layers between the ground on which the concrete or asphalt layer rests and the external face of the concrete or asphalt layer.

There are so-called "self-draining" concretes that are much more porous in order to facilitate the flow of water through the concrete layer. Such concretes can be used to create parking areas. These are concretes that have between 15 and 25% porosity and can have a water permeability commonly between 3 and 5mm/s. The increase in porosity results in a decrease in compressive strength. The cost of "self-draining" concrete is high, which limits its use. It is also necessary to pour the concrete on site and then wait for the structure to dry completely. It has been observed that these materials tend to clog up over time, which drastically reduces their ability to drain water.

There are also "to be laid" structures which are also made of concrete and which come in the form of a hollow core slab. The slab defines through holes which are intended to be filled with earth and vegetation or gravel. The surface of the cells represents a compromise between mechanical strength, water permeability and the intended use. The assembly of these structures is laborious and the resistance over time is poor, which implies regular interventions to maintain a reassuring appearance. It also appears that the cells filled with earth form depressions which store debris.

It also appears that concrete areas and structures contain a large amount of concrete, which makes them high energy consumers and therefore have an unfavourable carbon footprint. In periods of high heat, concrete stores heat and tends to form a heat island that makes the paved area unpleasant and tends to weaken the plants growing in the gaps and cells.

Polymer structures are also known, but these have poor resistance to climatic conditions and ultraviolet radiation.

Subject of the invention

An object of the invention is to provide a draining slab which has good water permeability while storing less heat than its concrete equivalent and which has a long service life.

This result is tended to be achieved by means of a prefabricated drainage slab intended for the manufacture of a floor for a vehicle parking area or an outdoor rest area, the drainage slab comprising a first face and a second face opposite in a first direction, the drainage slab being intended to rest on the second face. The drainage slab has drainage channels connecting the first face and the second face for evacuation of water through the drainage slab.

The drainage slab is remarkable in that the drainage slab has at least one support piece, at least one reinforcement at least partially covering the support piece in the first direction to form at least part of the first face and at least one lifting element intended to allow the drainage slab to be lifted. The at least one support piece is formed from a support material comprising a mineral binder and particles of a plant material embedded in the mineral binder. The support material is a porous material with open pores and which has a first value of mass content of particles of plant material of between 30 and 70%, the average length of the particles being between 10 and 100 mm. The at least one reinforcement is fixed to the at least one support piece and has a compressive strength greater than the compressive strength of the at least one support piece, the at least one reinforcement is made from at least one porous reinforcement material with open pores, the porosity of the at least one reinforcement material and of the support material forming the drainage channels.

Advantageously, the at least one reinforcement comprises a cover layer covering the at least one support piece to form all or part of the first face, the cover layer being porous with open pores and having a second value of mass content of particles of plant material of between 30 and 70%, the average length of the particles being between 10 and 100 mm, the cover layer having a porosity lower than a porosity of the at least one support piece.

In a particular configuration, the cover layer has a binder content that is greater than the binder content of the support material.

In an advantageous development, the cover layer has a thickness less than or equal to 50% of the thickness of the drainage slab in the first direction.

Preferably, the reinforcing material comprises a wearing course made of cement or concrete devoid of plant material particles or whose mass content value of plant material particles is less than 10% and in which the wearing course represents a surface area less than 50% of the surface area of the first face.

In a particular configuration, the wearing course extends over less than 50% of the thickness of the drainage slab.

In an advantageous development, the wearing course defines two treads extending parallel to each other at least from one edge of the drainage slab in a direction perpendicular to the first direction, the two treads being intended to receive the wheels of a motor vehicle.

Preferably, the reinforcing material penetrates into the surface cavities of the at least one support part to a depth of between 5 mm and 5 cm to form a fixing interface between the at least one reinforcement and the at least one support part.

In another advantageous development, the at least one lifting element opens onto the first face, the at least one lifting element having a frame partly embedded in a lifting material, the lifting material comprising a mineral binder and optionally particles of a plant material embedded in the mineral binder, the value of mass content of particles of plant material being less than 10%, the lifting material penetrating into the surface cavities of the at least one support part to a depth of between 5 mm and 5 cm to form a fixing interface between the at least one support part and the at least one lifting element.

In a particular configuration, the lifting material is a cement or concrete free of plant material particles.

Advantageously, the prefabricated drainage slab comprises a plurality of lifting elements, the lifting material extending along the at least one support piece to connect at least two lifting elements of the plurality of lifting elements.

Preferably, the lifting material defines a ring connecting the plurality of lifting elements in an observation passing through the first face and the second face, the plurality of lifting elements preferably comprising at least three lifting elements.

In an advantageous configuration, the ring is formed along the second face.

Preferably, the lifting material is a reinforcing material and the plurality of lifting elements are arranged in the treads.

In a particular embodiment, the drainage slab comprises at least one through hole extending from the first face to the second face, the side wall of the through hole being porous and formed of support material.

It is also advantageous if the prefabricated drainage slab includes at least one piece of equipment chosen from a table, a bench, an outdoor game, the equipment having at least one attachment to said at least one reinforcement.

The invention also relates to a construction whose floor absorbs less heat than a concrete floor and which has a longer lifespan than a floor made of polymer material while ensuring good drainage of water, particularly rainwater.

Brief description of the drawings

Other advantages and characteristics will emerge more clearly from the following description of particular embodiments and implementations of the invention given as non-limiting examples and shown in the appended drawings, in which:

: a schematic top view of a first embodiment of a drainage slab;

: a schematic view from below of the first embodiment of a drainage slab;

: a schematic sectional view along AA of the first embodiment of a drainage slab;

: a schematic sectional view along BB of the first embodiment of a drainage slab;

: a schematic top view of a second embodiment of a drainage slab;

: a schematic sectional view along AA of the second embodiment of a drainage slab.

Figures 1 to 6 illustrate a prefabricated drainage slab intended to form all or part of a construction which is an exterior element including, for example, a parking space for a vehicle, a cycle path, a footpath, a rest area. The rest area may be equipped with one or more games for children, for example a swing, a turnstile, a slide. The rest area may be equipped with a table, one or more benches, one or more chairs, one or more planters or greenery bins. The rest area may be equipped with one or more pieces of equipment for sports, for example for “street workout” with preferably a Roman chair or other equipment allowing, for example, to do pull-ups or to work other muscle groups.

The draining slab is a slab that has a first face 1 and a second face 2 that are opposite each other in a first direction Z that is substantially a vertical direction. The draining slab has a water permeability that is significant, that is to say that it allows significant circulation of water from the first face 1 to the second face 2, which facilitates the absorption of water by the ground on which the draining slab rests. Advantageously, the draining slab has a water permeability greater than 2 mm/s, more preferably greater than 3 mm/s and even more preferably greater than 4 mm/s in the first direction Z.

It is particularly advantageous if the drainage slab has a water permeability that is greater than the water permeability of the soil supporting the drainage slab so that the drainage slab does not limit the absorption of water by the soil during a heavy downpour. The drainage slab is intended to rest on the second face 2.

In order to allow water to flow, the drainage slab has drainage channels connecting the first face 1 and the second face 2 for water evacuation through the drainage slab. The materials forming the slab are mainly porous so that the flow of water is distributed over a large volume of the drainage slab. The use of a porous material facilitates the transport of water in directions perpendicular to the first direction Z to improve the evacuation of water on the contact surface between the second face 2 and the ground. This also makes it possible to use the entire volume of the drainage slab to achieve water retention if necessary. It is particularly advantageous for the porous materials to represent the majority of the volume of the drainage slab, preferably at least 70% of the volume, or even at least 80% of the volume. This solution is advantageous in a configuration where the slab is made of a material that is poorly permeable to water or waterproof and which is perforated by means of through holes that pass through the entire thickness of the slab. This configuration poses problems of mechanical strength and filling of the holes.

The drainage slab has at least one support part 3, at least one reinforcement 4 at least partially covering the support part 4 in the first direction Z and at least one lifting element 5 intended to allow the lifting of the drainage slab. The drainage slab is a monolithic element which is manufactured then transported from its place of manufacture to its place of use. The drainage slab is manufactured in a controlled environment then it is installed on the ground. The drainage slab is lifted by means of lifting equipment to be laid at its place of use. Once laid, the drainage slab is ready for use, it is only necessary to wait for a binder to dry.

The at least one support part 3 is formed from a support material comprising a mineral binder and particles of a plant material embedded in the mineral binder. The use of particles of a plant material makes it possible to form a support part whose capacity to store heat is lower for an equivalent in cement, concrete, reinforced concrete or any other mineral binder. The use of particles of a plant material embedded in the mineral binder makes it possible to have particles that are completely coated by the mineral binder, which makes it possible to ensure mechanical cohesion between the particles and to protect the particles against external aggression. The use of particles of plant material makes it possible to produce a material whose carbon footprint is improved in comparison with a drainage slab made of polymer material or only binder.

The carrier material is a porous, open-pore material. The carrier material has a first value of mass content of plant material particles between 30 and 70%. The average particle length is between 10 and 100mm.

The support material is a mixture comprising a mineral binder and particles of a plant material. The plant material may be wood, straw, cellulose, hemp or cork. The particles of plant material are preferably wood particles. Preferably, the particles of plant material are mainly wood particles (by volume) and preferably wood chips. Preferably, the mineral binder is chosen from a cement, a clay, a clay-based material, blast furnace slag or lime. It is also possible to use a concrete which is a mixture containing water, a binder for example cement and other elements, for example sand and possibly gravel. It is particularly advantageous for the mineral binder to contain a significant content and more preferably a majority of geosourced material.

The plant element particles are embedded in the mineral binder which ensures mechanical cohesion between the particles. The particles are covered by a layer of mineral binder to protect them from external aggressions. The particles are assembled randomly with respect to each other and they define channels and/or cavities inside the support 3.

It is advantageous if the particles of plant material are not completely covered by the binder and/or if the binder is porous or permeable to water so as to allow the particles of plant material to absorb part of the circulating water. Part of the water is absorbed by the particles, which reduces the flow to the ground. Once the particles are filled with water, the elimination of water allows the draining slab to be passively cooled by evaporation.

The support material has a first mass value in plant material particles of between 30% and 70% and preferably with a volume content of plant material particles of between 30 and 95%, more preferably the plant material particles represent a greater volume than the mineral binder. The mass content of plant material particles corresponds to the mass of the plant material particles relative to the total mass of the support material after drying. The volume content of plant material particles corresponds to the volume of the plant material particles relative to the total volume of the other materials of the support material after drying and without taking into account the porosity of the material. The use of such a content of plant material particles makes it possible to have a significant reduction in the mass of the construction panel in comparison with an equivalent panel exclusively made of concrete or reinforced concrete.

It is particularly interesting to have a support material that is porous in the solid state. The particles of plant material are arranged randomly relative to each other with possibly a preferred orientation linked to the manufacturing conditions and they define pores. The support material is open-pored. The pore size is greater than 1 mm and the porosity of the support material is different from the intrinsic porosity of the mineral binder. It is particularly advantageous for the support material to have a porosity of between 30% and 70%, which provides a good compromise between the density of the material, its compressive strength and its ability to absorb heat and therefore to form a heat island. Providing significant porosity makes it possible to maintain significant drainage capacities over time. As impurities enter the pores, the pore section decreases or some pores become clogged. Providing a material with high porosity ensures good drainage capacity throughout the life of the drainage slab.

Preferably, the majority in number of particles made of plant material has a length of between 1 and 100 mm. Particularly advantageously, the average length of the particles is between 10 and 100 mm, preferably between 10 and 60 mm, more preferably between 20 and 60 mm. The average length can be a simple average length. The use of such a length range makes it possible to form a material whose porosity and surface roughness are better controlled, in particular with microcavities and especially cavities whose volume is larger. The use of a mixture comprising a majority of particles whose size is preferably between 10 and 100 mm, preferably between 10 and 60 mm and whose mass and/or volume content of particles is high makes it possible to form a porous support with significant surface roughness. Even more preferably, the particles are wood chips which have a thickness mainly between 1 mm and 5 mm (in number). Such a distribution in length and thickness makes it possible to form a support material of reduced density, with satisfactory mechanical resistance and a good compromise between porosity and surface roughness. Roughness corresponds to the maximum height between a peak and a trough of the surface.

The volume of the at least one support piece 3 is greater than the volume of the at least one reinforcement element 4 and greater than the volume of the lifting element(s) 5. More preferably, the volume of the at least one support piece 3 represents at least 50% of the volume of the draining slab.

The porosity of the support material provides significant water permeability without necessarily having to form through holes from the first face to the second face. Porosity also limits the amount of material that can absorb heat and then release it later to form a heat island.

When the particles of plant material are wood particles and when the mineral binder is a cement or concrete, the density of the support material is between 600 and 1000 kg/ ^m3 , by varying the composition of the material, preferably it is equal to 800 kg/ ^m3 . Thanks to the high content of plant material particles and the porosity, a lighter material than raw concrete is obtained, i.e. a concrete that does not contain wooden elements and whose density is approximately 2300kg/ ^m3 . The drainage slab can be moved and then deposited using conventional lifting means, which facilitates the installation of the drainage slab in a short time.

The support material has a compressive strength that allows it to form a parking space for a motor vehicle, for example a car. The support material is capable of supporting a weight greater than or equal to 2000 kg, preferably less than 3000 kg. Advantageously, the support material has a compressive strength greater than 2 MPa, preferably greater than 2.5 MPa.

Preferably, the support part 1 has a porosity which represents between 30% and 50% of the total volume of the support part 1. Such a porosity value makes it possible to reduce the density of the support part, reduce its capacity to absorb heat, facilitate the formation of drainage channels connecting the first face and the second face while providing a material capable of supporting heavy loads.

The draining slab having a first face 1 intended to be heavily stressed, for example by the rolling of vehicles or pedestrian steps, it is preferable to use the at least one reinforcement 3 to protect the at least one support piece 3. The at least one reinforcement 3 is fixed to the at least one support piece 4 and has a compressive strength greater than the compressive strength of the at least one support piece 3, preferably at least 10% greater. The at least one reinforcement 4 is installed in a manner that cannot be dismantled relative to the at least one support piece 3.

The at least one reinforcement 4 covers at least a portion of the at least one support piece 3 in the first direction Z to form the first face 1 of the draining slab. Depending on the configurations, the at least one reinforcement 4 partially or completely covers the at least one support piece 3 in the first direction Z to form the first face 1 of the draining slab. It is advantageous for the at least one support piece 3 to be completely covered by the at least one reinforcement 4.

When the at least one reinforcement 4 completely covers one face of the support 3 to form the first face 1 of the draining slab, it is advantageous that at least part of the material(s) forming the reinforcement 4 comprises a porous material.

In a preferred embodiment, the at least one reinforcement 4 comprises a cover layer 4a covering the at least one support piece 3 to form all or part of the first face 1. The cover layer 4a is porous with open pores. The porosity of the cover layer 4a has an interface with the porosity of the support piece 3 to allow water to flow from the first face 1. Advantageously, it has a second value of mass content of particles of plant material of between 30 and 70%, the average length of the particles being between 10 and 100 mm. The cover layer has a compressive strength that is greater than the compressive strength of the support piece, which results in a reduction in the porosity value compared to what is present in the support piece 3. Even more advantageously, the cover layer has a binder content that is greater than the binder content of the support material. Preferably, the binder is a cement or a concrete. It is preferable that the difference in binder content between the reinforcement 4 and the support piece 3 is less than 20%.

In an advantageous configuration, the cover layer 4a forming the first face of the drainage slab has a low surface roughness, for example less than 3 mm. The particles of plant material present on the first surface are mainly arranged to have an external face perpendicular to the first direction Z. This precaution makes it possible to limit the wear of the particles of plant material forming the first surface 1 while ensuring significant porosity. Such a result can be obtained by forming the drainage slab by means of a mold inside which the cover layer 4a is poured and the bottom of the mold is used to define the shape of the first face 1. For example, the material intended to form the cover layer 4a is poured and then the material of the support part 3 is poured. It is preferable that the two materials have the same binder or compatible binders, which facilitates adhesion between the support part 3 and the cover layer 4a. It is also preferable if the support material is poured while the cover layer material is not yet set, i.e. still dry (wet-on-wet process).

The cover layer 4a is intended to form a layer that better resists mechanical stresses on the first surface 1 of the drainage slab, but it has a water permeability that is less than that of the support. It is therefore advantageous to limit as much as possible the thickness of the cover layer 4a beyond what is necessary to ensure good resistance of the first face 1. In an advantageous embodiment, the thickness of the cover layer 4a is greater than 3 cm, preferably greater than 5 cm. It is advantageous for the thickness of the cover layer 4a to be less than 10% of the total thickness of the drainage slab. The cover layer 4a may have a non-uniform thickness from one end to the other of the drainage slab with distinct zones in a direction which is perpendicular to the first direction Z. The difference in thickness makes it possible to functionalize the first surface 1. The difference in thickness may be associated with a difference in color of the material or with another visible parameter which may be used to define a circulation path for pedestrians or cycles.

There illustrates a configuration where the entire upper surface of the support part 3 is covered by the cover layer 4a with the exception of the lifting elements 5. On the other hand, the represents a draining slab or the first surface 1 is formed by a reinforcement 1 which has different materials, here the cover layer 4a and a wearing course 4b. the reinforcement covers the entire support part 3 with the exception of the lifting elements 5.

In a particular embodiment illustrated in , the reinforcement 4 has a wearing course 4b which corresponds to a covering layer having a compressive strength much greater than the compressive strength of the support piece 3. The wearing course 4b is preferably intended to receive heavy loads, for example a car.

It is advantageous for the wearing course 4b to be made of a material that includes a mineral binder and more generally a geosourced binder, preferably a cement or a concrete. It is also advantageous for the material of the wearing course 4b to be free of particles of plant material or to have a mass content value of particles of plant material of less than 10%. To obtain a high compressive strength value, the porosity of the wearing course 4b is low. Under these conditions, the water permeability of the material used is low and it is preferable for the wearing course 4a to represent a surface area of less than 50% of the surface area of the first face 1, more preferably, less than 33% or even less than 20% in an observation along the first direction Z.

In order to have a drainage slab that has good water permeability, it is advantageous to limit the thickness of the cover layer 4a relative to the total thickness of the drainage slab. It is advantageous to limit the thickness of the cover layer 4a to 50% or less of the thickness of the drainage slab. However, the lower the porosity of the cover layer 4a, the lower the thickness of the cover layer 4a relative to the thickness of the support piece 3. Preferably, the thickness is less than 30%, or even 20% or even 10% of the total thickness of the drainage slab.

Since the rolling surface 4b is intended to support heavy loads, it is particularly advantageous for the rolling surface 4b to extend over at least 10% of the surface of the first face 1 so as to distribute the mass of the load to be supported. The thickness of the draining slab occupied by the material of the rolling surface 4b is preferably less than 50% of the thickness of the draining slab so as not to excessively penalize the overall permeability of the draining slab.

In an advantageous embodiment, the wearing course 4b defines two treads extending parallel to each other at least from one edge of the drainage slab in a direction perpendicular to the first direction Z, for example in the longitudinal direction of the drainage slab. The two treads are intended to receive the wheels of a motor vehicle. It is preferable for the two treads to extend from one edge to the other of the drainage slab.

In this embodiment, it is preferable that the support 1 is completely covered by the reinforcement 4 and that the reinforcement 4 has a part formed by the cover layer 4a which is porous and a part formed by the wearing course 4b which is waterproof or weakly permeable to water as illustrated in FIG. .

To facilitate the absorption of forces from the wearing course 4b by the support part 3 and possibly by the covering layer 4a, it is advantageous to choose a wearing course material 4b which fits into the cavities of the porous material forming the support part 3 and possibly into the cavities of the porous material forming the covering layer 4a.

In order to ensure a good mechanical connection, the wearing course 4b and the support part 1 have complementary faces. The material of the wearing course is introduced into the surface cavities of the support part 3 which is made of porous material to fill the cavities. Preferably, the material of the wearing course is introduced into the material of the support part over a distance at least equal to 3 mm, preferably at least equal to 5 mm, even more preferably at least equal to 1 cm. This implies that the wearing course 4b is deposited after the formation of the support part.

When forming the drainage slab, it is advantageous to first form the support piece 1 of porous material and then form the wearing course 4b. When forming the wearing course 4b, it is advantageous to have a mineral binder poured. The mineral binder penetrates inside the cavities of the porous material which fixes the wearing course 4b with the at least one support piece 3. When pouring a mineral binder which is a cement or a concrete to form the wearing course 4b, the concrete is able to insert itself inside the support piece 3 over a distance of several millimeters, for example at least 5mm, preferably at least 10mm or even at least 15mm. Such a recess in the support piece 3 makes it possible to have good mechanical cohesion between the wearing course 4b and the support piece 3. The support piece 3 at least partly forms the mold which defines the shape of the wearing course 4b.

In an alternative embodiment, the wearing course 4b is formed before forming the support piece 3. It is advantageous to install a connecting piece inside the wearing course and for the connecting piece to protrude out of the wearing course to an area that is intended to be the support piece 3. When the support piece is cast, it embeds at least part of the connecting piece which then provides the mechanical connection between the wearing course 4b and the support piece 3. The connecting piece may be a metal mesh, a metal rod or another material.

The material of the wearing course may be reinforced concrete and the wearing course 4b is provided with a metal reinforcement which extends in the longitudinal direction of the tread.

The drainage slab being a prefabricated element, it is intended to be transported and then installed, which requires it to be monolithic, particularly during lifting operations. The lifting element 5 is monolithic with the support part 4 and the reinforcement(s) 4.

Preferably illustrated in Figures 1, 2, 5 and 6, the at least one lifting element 5 opens onto the first face 1. The at least one lifting element 5 has a reinforcement partly embedded in a lifting material. The lifting material ensures mechanical cohesion between the reinforcement and the support part 3. The lifting material comprises a mineral binder and possibly particles of a plant material embedded in the mineral binder. The lifting material may have a composition identical to the reinforcing material or to one of the reinforcing materials. The lifting material may have a composition identical to the material of the cover layer 4a, but it is preferable for it to have a composition identical to the material of the wearing course 4b, possibly without the metal reinforcement. In other words, it is advantageous for the lifting material to have a mass content value of particles of plant material which is less than 10% or even free of particles of plant material. It is particularly advantageous that the lifting element attaches directly to the support part 3. This allows the lifting material to penetrate into the surface cavities of the at least one support part 3 to a depth of between 5mm and 5cm to form a fixing interface between the at least one support part 3 with the at least one lifting element 5.

The reinforcement of the lifting element 5 may be a ring or a hook. It is also possible for the reinforcement to define a thread or any other means of attachment of an element which is removed once the drainage slab has been laid.

It is particularly advantageous if the lifting material is a cement or concrete free of particles of plant material because it has good mechanical performance and it fits into the crevices of the support part 3 which allows good mechanical cohesion between the support part 3 and the lifting element 5.

It is preferable that the drainage slab is provided with a plurality of lifting elements 5 which makes it possible to reduce the intensity of the stress on the support part 3 at the interface between the support part 3 and the lifting element 5 when the drainage slab is lifted. More preferably and as illustrated in FIGS. 2 and 5 , the lifting material extends along the at least one support part 3 to connect at least two lifting elements 5 of the plurality of lifting elements 5. The lifting material forms a mechanical connection between the lifting elements 5 and is continuously fixed to the support part 3 between the two lifting elements 5. This makes it possible to better distribute the lifting forces in the volume of the support part 3.

Even more preferably, the lifting material defines a ring 5a connecting the plurality of lifting elements 5 in an observation along the first direction Z. The plurality of lifting elements 5 preferably comprises at least three lifting elements 5, more preferably at least four or five lifting elements 5.

In order not to penalize the water permeability too much, it is advantageous that the ring 5a is formed along the second face 2 as illustrated in . The significant porosity inside the support part 1 makes it possible to better distribute the quantity of water to be drained in all directions and in particular on either side of the ring 5a. The use of a ring 5a is particularly advantageous when the first face 1 is devoid of a tread or devoid of a tread having a sufficient surface area.

In a preferred embodiment illustrated in , the drainage slab has one or more wearing course areas, for example several treads, it is then advantageous to produce the reinforcing material in accordance with a lifting material. In other words, the lifting material has a composition which is in accordance with a composition of a reinforcing material and preferably with a wearing material. It is then preferable for the plurality of lifting elements 5 to be arranged in the treads. The lifting elements are held fixedly to the tread(s) and the tread is held fixedly to the support part 3. This makes it possible to reduce the surface area used by a material having a low water permeability. It is advantageous for the tread to form a ring 5a to which the lifting elements 5 are directly fixed.

In an advantageous configuration, the drainage slab defines at least one through hole 6 extending from the first face 1 to the second face 2. The side wall of the through hole 6 is porous and formed mainly of support material. The porosity of the support piece 3 makes it possible to evacuate part of the water from the side walls to the through hole. Once the drainage slab is installed, the through hole 6 is advantageously filled with soil or another substrate capable of receiving and growing vegetation. The porosity facilitates water exchanges over the entire thickness of the through hole 6. The roots can enter the support piece and/or the cover layer 4a.

The drainage slab may form the floor of a playground, a leisure area or a rest area. The drainage slab is intended to support on its first face 1 at least one piece of equipment which is fixedly mounted to the drainage slab. Depending on the configurations, the equipment may be fixed to the support, to the covering layer, to the wearing course or to a lifting material area.

Several drainage slabs can be arranged next to each other. It is advantageous if the edges of the slabs define complementary shapes that allow the drainage slabs to be placed next to each other, for example a recess 7 as illustrated in FIGS. 3 and 6. More advantageously, the edges are made of support material with possibly the covering layer for the part intended to form the first face. In this way, two drainage slabs placed next to each other and having their edges arranged one on top of the other are able to allow water to flow under conditions substantially identical to the rest of the drainage slab.

The support piece 4 and the cover layer 4a having a high content of plant material particles, the density of the drainage slab is lower than equivalent concrete constructions, which facilitates handling. The high content of plant material particles also makes it possible to fix one or more pieces of equipment directly in the cover layer 4a and/or in the support piece 3 in a simple manner, for example by screwing. The high content of plant material particles also makes it possible to cut the drainage slab in order to better adapt the shape of the drainage slab to a new dimensional constraint.

In addition to through holes or instead of through holes, the drainage slab may have blind holes.

Claims (18)

Prefabricated drainage slab intended for the manufacture of a floor for a vehicle parking area or an outdoor rest area, the drainage slab comprising:
- a first face (1) and a second face (2) opposite in a first direction (Z), the draining slab being intended to rest on the second face (2), the draining slab having drainage channels connecting the first face (1) and the second face (2) for evacuation of water through the draining slab;
- at least one support part (3) formed from a support material comprising a mineral binder and particles of a plant material embedded in the mineral binder, the support material being a porous material with open pores;
- at least one reinforcement (4) at least partially covering the support part (3) in the first direction (Z) to form at least part of the first face (1), the at least one reinforcement (4) being fixed to the at least one support part (3) and having a compressive strength greater than the compressive strength of the at least one support part (3);
characterized in that:
- the particles of plant material are not completely covered by the binder and/or the binder is porous or permeable to water so as to allow the particles of plant material to absorb part of the circulating water;
- the support material has a first value of mass content of plant material particles between 30 and 70%, the average length of the particles being between 10 and 100 mm;
- the at least one reinforcement (4) is made of at least one open-pore porous reinforcement material, the porosity of the at least one reinforcement material and of the support material forming the drainage channels; and
comprising at least one lifting element (5) opening onto the first face (1) and intended to allow the lifting of the drainage slab. Prefabricated drainage slab according to claim 1 wherein the at least one reinforcement (4) comprises a cover layer (4a) covering the at least one support piece (3) to form all or part of the first face (1), the cover layer (4a) being porous with open pores and having a second value of mass content of particles of plant material of between 30 and 70%, the average length of the particles being between 10 and 100 mm, the cover layer (4a) having a porosity lower than a porosity of the at least one support piece. (3) A prefabricated drainage slab according to claim 2 wherein the cover layer (4a) has a binder content which is greater than the binder content of the support material. Prefabricated drainage slab according to one of claims 2 and 3 in which the cover layer (4a) has a thickness less than or equal to 50% of the thickness of the prefabricated drainage slab in the first direction (Z). Prefabricated drainage slab according to one of claims 1 and 2 in which the reinforcing material comprises a wearing course (4b) made of cement or concrete devoid of particles of plant material or whose mass content value of particles of plant material is less than 10% and in which the wearing course (4b) represents a surface area less than 50% of the surface area of the first face (1). Prefabricated drainage slab according to claim 5 in which the wearing course (4b) extends over less than 50% of the thickness of the drainage slab. Drainage slab (1) according to one of claims 5 and 6 in which the wearing course (4b) defines two treads extending parallel to each other at least from one edge of the prefabricated drainage slab in a direction perpendicular to the first direction (Z), the two treads being capable of receiving wheels of a motor vehicle. Prefabricated drainage slab according to any one of claims 5 to 7 in which the reinforcing material penetrates into the surface cavities of the at least one support piece (3) to a depth of between 5mm and 5cm to form a fixing interface between the at least one reinforcement (4) and the at least one support piece (3). Prefabricated drainage slab according to any one of the preceding claims, in which the at least one lifting element (5) opens onto the first face (1), the at least one lifting element (5) having a reinforcement partly embedded in a lifting material, the lifting material comprising a mineral binder and optionally particles of a plant material embedded in the mineral binder, the value of the mass content of particles of plant material being less than 10%, the lifting material penetrating into the surface cavities of the at least one support part (1) to a depth of between 5 mm and 5 cm to form a fixing interface between the at least one support part (3) with the at least one lifting element (5). Prefabricated drainage slab according to claim 9 in which the lifting material is a cement or a concrete free of particles of plant material. A prefabricated drainage slab according to any one of claims 9 to 10 comprising a plurality of lifting elements (5), the lifting material extending along the at least one support piece (3) for connecting at least two lifting elements (5) of the plurality of lifting elements (5). Prefabricated drainage slab according to the preceding claim in which the lifting material defines a ring (5a) connecting the plurality of lifting elements (5) in an observation passing through the first face (1) and the second face (2), the plurality of lifting elements (5) preferably comprising at least three lifting elements (5). Prefabricated drainage slab according to the preceding claim in which the ring (5a) is formed along the second face (2). A prefabricated drainage slab according to claim 9 when dependent on claim 7 wherein the lifting material is a reinforcing material and the plurality of lifting elements (5) are arranged in the treads. Prefabricated drainage slab according to any one of the preceding claims comprising at least one through hole (6) extending from the first face (1) to the second face (2), the side wall of the through hole being porous and formed of support material. Prefabricated drainage slab according to any one of the preceding claims comprising at least one piece of equipment chosen from a table, a bench, an outdoor game, the equipment having at least one attachment to said at least one reinforcement (4). Construction comprising one or more prefabricated drainage slabs according to any one of the preceding claims, the prefabricated drainage slab being intended to form the floor of the construction, the construction being preferentially chosen from a parking area for a vehicle, a pedestrian path, a cycle path, a play area and a rest area. Construction according to the preceding claim in which the construction is a parking lot intended to receive one or more vehicles, the floor of the parking lot being formed by at least one prefabricated draining slab according to any one of claims 5 to 14.