Composite concrete slab for creating a floor covering that mitigates the urban heat island effect

Abstract

The invention relates to a composite concrete slab (1A) for creating a floor covering that mitigates the urban heat island effect, having a surface facing down and a surface opposite the surface facing down, characterized in that the slab comprises a structural concrete layer (2) having a tensile strength in splitting greater than 3.5 MPa and an Albedo value between 0.25 and 0.60, and at least one non-structural concrete portion (3) that absorbs and retains water, arranged with the structural concrete layer (2) to form all or part of the surface facing down. Figure to be published with the abstract: Fig. 2

Description

Title of the invention: Composite concrete slab for creating a floor covering that mitigates the urban heat island effect TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to the field of elements intended for the development of outdoor spaces.

[0002] The invention relates more particularly to a composite concrete slab for the production of a floor covering, offering a mitigation of the urban heat island effect having a laying surface on the ground and a surface opposite to the laying surface.

[0003] By floor, we mean any flat surface on which the slab rests. STATE OF THE ART

[0004] Faced with climate change combined with the densification of housing and the use of air conditioning, we are seeing a generalization of the heat island phenomenon (localized increases in air and surface temperatures recorded in urban areas compared to peripheral areas) making public space more uncomfortable or even, in some cases, unsuitable for use for the most sensitive populations.

[0005] The main properties of materials and products used in urban environments that can influence the "heat island" effect are: albedo (ability to reflect energy received by radiation), emissivity (ability to dissipate heat by radiation), thermal capacity (ability to store heat), thermal conductivity (ability to conduct heat), thickness and volume, as well as permeability and water retention capacity.

[0006] Among the techniques known to reduce the urban heat island effect, there are passive means including the development of surfaces or volumes capable of containing and evaporating water (brought and stored during previous rains), evaporation being a strongly endothermic natural phenomenon.

[0007] Concrete and concrete products, which are important components of urban spaces, provide significant thermal inertia, allowing for heat storage and temperature regulation. However, during prolonged heat waves, this inertia may prove insufficient and detrimental. Indeed, when the temperature does not decrease sufficiently, daytime heat is absorbed but cannot be fully dissipated at night, and the stored energy gradually becomes substantial and can contribute to exacerbating the urban heat island effect in the following days.

[0008] To overcome the inertia of concrete, concrete flooring solutions with draining (i.e., permeable) properties have been developed. These floorings utilize two types of concrete: ready-mix concrete and factory-prefabricated products.

[0009] With regard to prefabricated products in particular, several types of solutions exist for ensuring rainwater drainage, but these products inherently absorb little water. These solutions mainly include porous pavers, pavers with wide joints, and permeable slabs. In the case of the latter two types of pavers, water drainage occurs preferentially between the joints or in the spaces left empty within the product.

[0010] We also know from patent application EP2738148 another paving solution made of ceramic aggregates giving it a water retention capacity of 0.20 g / cm² to combat the heat island phenomenon.

[0011] The prior art solutions just described remain limited in terms of effectiveness, each of them acting / intervening only on a part of the characteristics influencing the heat island phenomenon, such as albedo or water retention capacity.

[0012] The invention aims to remedy these problems by proposing a composite concrete slab for the creation of a floor covering offering improved mitigation of the urban heat island effect.

[0013] The invention also aims to provide a modular concrete composite slab. SUBJECT OF THE INVENTION

[0014] To this end, and according to a first aspect, the invention proposes a composite concrete slab for the creation of a floor covering offering a mitigation of the urban heat island effect, having a face laid on the ground and a face opposite to the face laid, characterized in that the slab comprises a structural layer of concrete having a mechanical resistance in tensile strength by splitting greater than 3.5 MPa and an Albedo value between 0.25 and 0.60, and at least a non-structural part of water-absorbing and water-retaining concrete arranged with the structural layer of concrete to form in whole or in part the face laid.

[0015] Thus, thanks to the presence of a non-structural, water-absorbing and water-retaining concrete, integrated into or combined with a structural concrete that provides the mechanical resistance of the composite slab, some of the water drained during rain or watering episodes is absorbed by the non-structural part and subsequently released through evaporation when it is hot. This helps to lower the temperature of the composite slab and contributes to reducing the urban heat island effect.

[0016] Advantageously, the non-structural part of concrete is arranged within the structural layer of concrete so as to present at least one area flush with the laying face.

[0017] Advantageously, the non-structural part of concrete is arranged within the structural layer of concrete so as to present at least one area flush with the face opposite the laying face.

[0018] Advantageously, the structural layer of concrete comprises a hollow cavity filled with a concrete composition forming the non-structural part of concrete.

[0019] Advantageously, the structural layer of concrete comprises a plurality of channels open on the laying face at least and filled respectively with a concrete composition forming the non-structural part of concrete.

[0020] Advantageously, the non-structural part of concrete forms a sub-layer of the structural layer of concrete.

[0021] Advantageously, the structural layer of concrete has a luminance value between 35 and 85.

[0022] Advantageously, the structural layer of concrete has a slip resistance of at least 35.

[0023] Advantageously, the concrete of the structural layer comprises a mineral binder and mineral fillers based on secondary raw materials.

[0024] Advantageously, the concrete of the structural layer is a draining concrete.

[0025] Advantageously, the concrete of the structural layer has a carbon footprint less than 280 kg CO2eq / m3.

[0026] Advantageously, the concrete of the non-structural part comprises a mineral binder, advantageously hydraulic, an absorbent agent and polymer or vegetable fibers.

[0027] Advantageously, the concrete of the non-structural part comprises bio-based aggregates or aggregates having a water absorption coefficient (mass of water absorbed expressed as a percentage of the dry mass of an aggregate) of between 0.5% and 50% of their dry mass chosen without limitation from expanded clay aggregates, cellular concrete aggregates, textile shreds.

[0028] Advantageously, the concrete of the non-structural part is a concrete of mineral or agro-sourced origin with a density of 150 to 1200 kg / m3. BRIEF DESCRIPTION OF THE FIGURES

[0029] Other features and advantages of the invention will become apparent from the detailed description of the invention which follows with reference to the accompanying figures and in which:

[0030] [Fig.1] Fig.1 represents a schematic perspective view of a slab according to a first example of embodiment;

[0031] [Fig.2] The [Fig.2] represents a schematic cross-sectional view of the slab of the [Fig.1];

[0032] [Fig.3] Fig.3 represents a schematic view from below of the slab of Fig.1

[0033] [Fig.4] The [Fig.4] represents a schematic top view of the slab of the [Fig.1];

[0034] [Fig. 5] Fig. 5 represents a schematic cross-sectional view of a slab along a second example of implementation;

[0035] [Fig.6a]

[0036] [Fig.6b] Figure 6 represents a schematic view (a) in section and (b) from below of a slab according to a third embodiment;

[0037] [Fig.7] Fig.7 represents a schematic cross-sectional view of a slab along a fourth example of implementation.

[0038] For greater clarity, identical or similar elements of the different embodiments are identified by identical reference signs throughout the figures. DETAILED DESCRIPTION OF THE INVENTION

[0039] With reference to Figures 1 to 7, examples of composite concrete slabs IA, IB, IC, 1D are described for creating a floor covering that mitigates the urban heat island effect. These slabs have a lower face 10 designed for installation on the floor to be covered and an upper face 11 opposite the installation face.

[0040] In what follows, the face intended to be oriented towards the ground, when the slab is in the laying position, shall be designated interchangeably as "laying face", "rear face", "underside of slab", "lower face" and designated in the figures by reference 10. Similarly, the face opposite the laying face shall be named interchangeably as "opposite face", "visible face", "front face" or "upper face" and designated in the figures by reference 11.

[0041] The composite slabs according to the invention comprise a structural layer of concrete 2 having a mechanical resistance in tensile strength by splitting greater than 3.5 MPa and an Albedo value between 0.25 and 0.60 and at least one non-structural part of water-absorbing and water-retaining concrete 3 associated with or integrated into the structural layer of concrete 2.

[0042] The non-structural concrete portion 3 is arranged with the structural concrete layer 2 to form all or part of the bedding face 10 of the composite slab. It may also be provided that the non-structural concrete portion 3 is also arranged with the structural concrete layer 2 to present visible areas on the upper surface (front face) of the composite slab once it has been laid. The advantage of Providing visible areas on the surface of the non-structural part of the concrete that absorbs and retains water allows for the direct capture of water on the surface of the composite slab laid.

[0043] The concrete of the structural layer 2, advantageously draining, provides the strength of the composite slab. It preferably comprises a mineral binder and mineral fillers, advantageously based on secondary raw materials. By "secondary raw material" is meant waste that has been transformed and / or combined in order to obtain a product that can be reused in manufacturing processes, in particular as a replacement for the initial raw material.

[0044] According to a preferred embodiment, the concrete of the structural layer 2 will be produced to have a carbon footprint of less than 280 kg CO2eq / m3.

[0045] The concrete of the non-structural part 3 can be a concrete of mineral or agro-sourced origin with a density of 150 to 1200 kg / m3. Preferably, it comprises an absorbent material based on a mineral binder, advantageously hydraulic, polymer fibers, for example polypropylene, or plant fibers, such as cellulose, and an absorbent agent.

[0046] The concrete of the non-structural part 3 also advantageously comprises bio-based aggregates or aggregates having a water absorption coefficient of between 0.5 and 50% of their dry mass chosen in a non-limiting manner from expanded clay aggregates, cellular concrete aggregates, textile shreds.

[0047] In the example illustrated in Figures 1 to 3, the composite slab IA comprises a structural concrete layer 2, the lower and upper faces of which respectively define the underside 10 of the slab and the visible face 11 of the composite slab IA. The structural concrete layer 2 comprises, on its lower (or rear) face, a recessed cavity 4 having, in the illustrated example, a depth extending over nearly half the height of the structural concrete layer. The structural layer 2 further comprises channels 5 passing through, in the example four straight channels, the upper part of the structural concrete layer 2, between the upper face of the structural concrete layer 2 and the cavity 4. The cavity 4 and the channels 5 are filled with non-structural concrete, thus forming the non-structural concrete part 3 of the composite slab IA.The footprint 4 and the channels 5 are provided within the structural layer of concrete 2 to define a non-structural part of concrete 3 and a structural part of concrete that are axially symmetrical.

[0048] As shown in Figures 3 and 4, the non-structural part 3 thus has one area flush with the installation face and four areas flush with the visible face. Thanks to the visible presence of the concrete of the non-structural part on the surface of the composite slab, water can also be directly collected at the surface.

[0049] In the illustrated example, the cavity 4 has a trapezoidal cross-section, the base of the shape defining the area flush with the mounting face. It is understood that the cavity 4 is not limited to this shape and that any other shape can be considered without departing from the scope of the invention. The same applies to the number and dimensions of the channels 5.

[0050] Advantageously, the non-structural concrete portion 3 occupies 40 to 50% of the volume of the structural concrete layer 2. Furthermore, the footprint 4 is designed so that the flush area of ​​the non-structural concrete portion 3 forms the underside 10 of the composite slab IA for the majority. By "majority," we mean that the surface area of ​​the back face 10 of the composite slab is occupied by the non-structural concrete portion 3 by more than 80%.

[0051] The advantage of this arrangement of the non-structural part of concrete 3 in the structural layer of concrete 2 is the realization of a composite slab having a high albedo with a decreased thermal conductivity when dry and a high absorption with an increased evapotranspiration capacity when wet.

[0052] In the example illustrated in [Fig. 5], the composite slab IB replicates the arrangement of the previously described composite slab, except that it lacks channels opening onto the upper face of the structural concrete layer 2. The structural concrete layer 2 thus comprises, on its lower face, a recessed cavity 4, trapezoidal in shape in this example, filled with a concrete composition to form the non-structural concrete portion 3 of the composite slab. As before, the cavity 4 has a depth extending to approximately half the height of the structural concrete layer. It is understood that the cavity 4 is not limited to this shape or dimension and that any other shape and / or dimension can be considered without departing from the scope of the invention. The advantage of this configuration is that it provides a uniform surface, thus improving the aesthetic appearance of the slab.

[0053] In the example illustrated in Figure 6, the structural concrete layer 2 comprises a plurality of channels 5 traversing, in this example four straight channels, extending through the structural concrete layer 2 of the slab, between the lower and upper faces of the structural concrete layer 2. Each channel 5 is filled with a concrete composition forming the non-structural concrete portion 3. The channels 5 are evenly distributed within the structural concrete layer 2 so as to provide homogeneous absorption and disabsorption while offering a resistant IC composite slab. The advantage of this arrangement is to have a larger water-capture surface on the upper face.

[0054] In the examples just described, the non-structural concrete part 3 is inserted into the structural concrete layer 2. In the example illustrated in [Fig. 7], The non-structural concrete layer 3 forms a sub-layer of the structural concrete layer 2. It thus forms the entire bearing surface of the 1D composite slab, and only the structural concrete layer 2 will be visible. In the example shown, the non-structural concrete layer 3 occupies more than 50% of the volume of the composite slab. The advantage of this arrangement lies in the simplicity of the manufacturing process.

[0055] Whatever the arrangement implemented, those illustrated as well as those not illustrated but falling within the scope of the invention, the structural layer of concrete 2 will preferably have a luminance value between 35 and 85 and / or a slip resistance of at least 35.

[0056] The assembly of the two concretes (resistant / absorbent) is achieved by adhesion, the absorbent concrete adhering to the concrete providing the resistance.

[0057]

[0058]

[0059]

[0060]

[0061]

[0062] Non-limiting examples of concrete compositions for the production of slabs illustrated in figures 1 to 5 and 7 and the slab performances obtained are given below for illustrative purposes. Example 1 - Composite slab according to the embodiment illustrated in figures 14 The composite slab contains an insertion of hempcrete within a low-carbon, high-albedo structural concrete. It measures 30 cm x 30 cm x 10 cm. Composition of the visible, resistant layer: Composition of the visible insert on the absorbing surface: Hempcrete made from hemp hurd, the central part of the hemp stem. Panel performance: Luminance (structural concrete) 72 Albedo (structural concrete) 0.425 Water absorption (mass %) 15.1% Effusivity (J.m2.K'.S1 / 2) 1634 Capillary absorption (% of potentially absorbable water) 24.8% Example 2 - Composite slab according to the embodiment illustrated in [Fig.5]

[0063] The composite slab contains an insertion of hemp concrete in a low carbon structural concrete with high albedo.

[0064] The slab has dimensions of 30 cm x 30 cm x 10 cm, the resistant concrete layer presenting a thickness of 4 cm while the absorbent concrete layer presenting a thickness of 6 cm.

[0065] Composition of the resistant visible layer:

[0066] Composition of the non-visible absorbent sub-layer: Hempcrete based on Hemp shives, the central part of the hemp stem.

[0067] Panel performance:

[0068] Example 3 - Composite slab according to the embodiment illustrated in [Fig.7]

[0069] The composite slab consists of two layers: the surface layer ensuring the product's resistance and an underlayer (non-visible layer) of absorbent hempcrete.

[0070] The slab has dimensions of 30 cm x 30 cm x 10 cm, the resistant concrete layer presenting a thickness of 4 cm while the absorbent concrete layer presenting a thickness of 6 cm.

[0071] Composition of the resistant visible layer:

[0072] Composition of non-visible absorbent underlayer: Hempcrete based on hemp shives, the central part of the hemp stem.

[0073] Panel performance:

[0074] The invention is described above by way of example. It is understood that a person skilled in the art is able to carry out different embodiments of the invention without departing from the scope of the invention.

Claims

Demands

1. Composite concrete slab (IA, IB, IC, 1D) for the creation of a floor covering offering mitigation of the urban heat island effect, having a face laid on the ground and a face opposite the face laid, characterized in that the slab comprises: - a structural layer of concrete (2) formed of structural concrete, said structural layer of concrete having a mechanical resistance in tensile strength by splitting greater than 3.5 MPa and an Albedo value between 0.25 and 0.60, and - at least one non-structural part of concrete (3) absorbing and retaining water, formed of non-structural concrete, arranged with the structural layer of concrete (2) to form in whole or in part the face laid of the slab.

2. Composite slab (IA, IB, IC, 1D) of concrete according to claim 1, characterized in that the non-structural part of concrete (3) is arranged within the structural layer of concrete (2) so as to present at least one area flush with the laying face.

3. Composite slab (IA, IB, IC, 1D) of concrete according to claim 1 or claim 2, characterized in that the non-structural part of concrete (3) is arranged within the structural layer of concrete (2) so as to present at least one area flush with the face opposite the laying face.

4. Composite slab (IA, IB, IC, 1D) of concrete according to any one of claims 1 to 3, characterized in that the structural layer of concrete (2) comprises a hollow imprint (4) filled with a concrete composition forming the non-structural part of concrete (3).

5. Composite slab (IA, IB, IC, 1D) of concrete according to any one of claims 1 to 4, characterized in that the structural layer of concrete (2) comprises a plurality of channels (5) open at least on the laying face and filled respectively with a concrete composition forming the non-structural part of concrete (3).

6. Composite slab (IA, IB, IC, 1D) of concrete according to claim 1, characterized in that the non-structural part of concrete (3) forms a sub-layer of the structural layer of concrete (2).

7. Composite slab (IA, IB, IC, 1D) made of concrete according to any one of claims 1 to 6, characterized in that the structural layer concrete (2) has a luminance value between 35 and

8. OJ. Composite slab (IA, IB, IC, 1D) of concrete according to any one of claims 1 to 7, characterized in that the structural layer of concrete (2) has a slip resistance of at least 35.

9. Composite slab (IA, IB, IC, 1D) of concrete according to any one of claims 1 to 8, characterized in that the concrete of the structural layer (2) comprises a mineral binder and mineral fillers based on secondary raw materials.

10. Composite slab (IA, IB, IC, 1D) of concrete according to any one of claims 1 to 9, characterized in that the concrete of the structural layer (2) is a draining concrete.

11. Composite slab (IA, IB, IC, 1D) of concrete according to any one of claims 1 to 10, characterized in that the concrete of the structural layer (2) has a carbon footprint (4) of less than 280 kg CO2eq / m3.

12. Composite slab (IA, IB, IC, 1D) of concrete according to any one of claims 1 to 11, characterized in that the concrete of the non-structural part (3) comprises a mineral binder, an absorbent agent and polymer or vegetable fibers.

13. Composite slab (IA, IB, IC, 1D) in concrete according to any one of claims 1 to 12, characterized in that the concrete of the non-structural part (3) comprises bio-based aggregates or aggregates having a water absorption coefficient of between 0.5% and 50% of their dry mass selected without limitation from expanded clay aggregates, cellular concrete aggregates, textile shreds.

14. Composite slab (IA, IB, IC, 1D) made of concrete according to any one of claims 1 to 13, characterized in that the concrete of the non-structural part (3) is a concrete of mineral or agro-sourced origin with a density of 150 to 1200 kg / m3.

Images