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 at 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, in whole or in part, the surface facing down. Figure to be published with the abstract: Fig. 2

Description

Title of the invention: Composite concrete slab for the creation of a floor covering offering attenuation of 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 producing a floor covering, offering attenuation of the urban heat island effect, having a surface for laying on the ground and a surface opposite the laying surface.

[0003] By ground is meant 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 generalisation of the phenomenon of heat islands (localised increases in air and surface temperatures recorded in urban areas compared to peripheral areas) making public spaces more uncomfortable and even, in certain cases, unsuitable for use by 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 (capacity to reflect energy received by radiation), emissivity (capacity to evacuate heat by radiation), thermal capacity (capacity to store heat), thermal conductivity (capacity to conduct heat), thickness and volume as well as permeability and water retention capacity.

[0006] Among the techniques known for reducing 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 highly endothermic natural phenomenon.

[0007] Concrete material and concrete products, which are important components of urban space, provide significant thermal inertia that allows heat storage and temperature smoothing. However, during long periods of heatwaves, this inertia may not be sufficient and may in fact become detrimental. Indeed, when the temperature does not decrease sufficiently, daytime heat is captured but cannot be fully evacuated at night, and the stored energy then gradually becomes significant and can contribute to increasing the phenomenon of urban heat islands in the following days.

[0008] In order to overcome the inertia of concrete, coating solutions have been developed. concrete floor with draining properties (i.e. permeable). These coverings use two families of concrete: ready-mix concrete and factory-prefabricated products.

[0009] With regard to prefabricated products in particular, there are several types of solutions for ensuring rainwater drainage, but these products intrinsically absorb little water. These are mainly porous paving stones, paving stones with wide joints and draining slabs. In the case of the last two types of paving stones, water drainage is preferably carried out between joints or in the spaces left empty in the product.

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

[0011] The prior art solutions just described remain, however, 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 production of a floor covering offering improved attenuation of the urban heat island effect.

[0013] The invention also aims to propose 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 producing a floor covering offering attenuation of the urban heat island effect, having a face for laying on the ground and a face opposite the laying face, characterized in that the slab comprises a structural layer of concrete having a mechanical resistance in tensile splitting greater than 3.5 MPa and an Albedo value of between 0.25 and 0.60, and at least one 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 laying face.

[0015] Thus, thanks to the presence of a non-structural concrete that absorbs and retains water, integrated or associated with a structural concrete ensuring the mechanical resistance of the composite slab, part of the water drained during episodes of rain or watering is absorbed by the non-structural part and subsequently returned by evaporation when it is hot. This thus makes it possible to reduce the temperature of the composite slab and to contribute to a reduction in the heat island effects.

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

[0017] Advantageously, the non-structural portion 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 impression filled with a concrete composition forming the non-structural portion 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 portion of concrete forms a sub-layer of the structural layer of concrete.

[0021] Advantageously, the structural layer of concrete has a luminance value of 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 plant fibers.

[0027] Advantageously, the concrete of the non-structural part comprises bio-sourced aggregates or aggregates having a water absorption coefficient (mass of water absorbed expressed in the form of a percentage of the dry mass of an aggregate) of between 0.5% and 50% of their dry mass chosen in a non-limiting manner from expanded clay aggregates, cellular concrete aggregates, textile chips.

[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 characteristics and advantages of the invention will emerge from the detailed description of the invention which follows with reference to the appended figures and in which:

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

[0031] [Fig.2] [Fig.2] represents a schematic sectional view of the slab of [Fig.l];

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

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

[0034] [Fig.5] [Fig.5] represents a schematic sectional view of a slab according to a second example of realization;

[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 exemplary embodiment;

[0037] [Fig.7] [Fig.7] represents a schematic sectional view of a slab according to a fourth embodiment.

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

[0039] In relation to Figures 1 to 7, examples of composite slabs IA, IB, IC, 1D made of concrete are described for the production of a floor covering offering attenuation of the urban heat island effect. These slabs have a lower face 10 provided for laying on the ground to be covered and an upper face 11 opposite the laying face.

[0040] In the following, the face intended to be oriented towards the ground, when the slab is in the laying position, will be designated indifferently by “laying face”, “rear face”, “underside of slab”, “lower face” and designated in the figures by the reference 10. Similarly, the face opposite the laying face will be named indifferently “opposite face”, “visible face”, “front face” or “upper face” and designated in the figures by the reference 11.

[0041] The composite slabs according to the invention comprise a structural layer of concrete 2 having a mechanical resistance in tensile splitting greater than 3.5 MPa and an Albedo value of between 0.25 and 0.60 and at least one non-structural part of concrete 3 absorbing and retaining water associated or integrated in 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 laying 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 water-absorbing and water-retaining concrete portion is to allow water to be directly captured on the surface of the laid composite slab.

[0043] The concrete of the structural layer 2, advantageously draining, ensures 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, with a view to obtaining 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 made to have a carbon footprint of less than 280 kg CO2eq / m3.

[0045] The concrete of the non-structural part 3 may 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-sourced 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 chips.

[0047] In the example illustrated in Figures 1 to 3, the composite slab IA comprises a structural concrete layer 2 whose lower and upper faces respectively delimit the underside 10 of the slab and the visible face 11 of the composite slab 1A. The structural concrete layer 2 comprises, on its lower (or rear) face, a hollow imprint 4 having, in the example illustrated, 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 rectilinear channels, the upper part of the structural concrete layer 2, between the upper face of the structural concrete layer 2 and the imprint 4. The imprint 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 imprint 4 and the channels 5 are provided within the structural concrete layer 2 to define an axially symmetrical non-structural concrete part 3 and a structural concrete part.

[0048] As shown in Figures 3 and 4, the non-structural part 3 thus has an area flush with the laying 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, the water can also be directly captured on the surface.

[0049] In the example illustrated, the imprint 4 has a trapezoidal section, the base of the shape defining the area flush with the laying face. It is of course obvious that the imprint 4 is not limited to this shape and that any other shape can be envisaged without departing from the scope of the invention. The same applies to the number and channel sizing 5.

[0050] Advantageously, the non-structural concrete portion 3 occupies 40 to 50% of the volume of the structural concrete layer 2. Furthermore, the imprint 4 is provided so that the flush zone of the non-structural concrete portion 3 mainly forms the underside 10 of the composite slab IA. By “mainly”, we mean an occupation of the surface area of ​​the rear face 10 of the composite slab by the non-structural concrete portion 3 greater 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 production of a composite slab having a high albedo with reduced thermal conductivity when dry and high absorption with increased evapotranspiration power when wet.

[0052] In the example illustrated in [Fig. 5], the composite slab 1B takes up the arrangement of the composite slab previously described except that it is devoid of channels opening onto the upper face of the structural concrete layer 2. The structural concrete layer 2 thus comprises, on its lower face, a hollow impression 4, in the example of trapezoidal shape, filled with a concrete composition to form the non-structural concrete part 3 of the composite slab. As before, the impression 4 has a depth extending over nearly half the height of the structural concrete layer. It is of course obvious that the impression 4 is not limited to this shape or to this dimensioning and that any other shape and / or dimension can be envisaged without departing from the scope of the invention. The advantage of this configuration is to offer 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 passing through, in the example four rectilinear channels, extending from one side to the other of 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 equally distributed within the structural concrete layer 2 so as to provide homogeneous absorption and deabsorption while providing a strong 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 portion 3 is inserted into the structural concrete layer 2. In the example illustrated in [Fig.7], the non-structural concrete portion 3 forms a sub-layer of the structural concrete layer 2. It thus forms the entire ground-laying face of the composite slab 1D and only the structural concrete layer 2 will be visible. In the example illustrated, the non-structural concrete portion 3 occupies a volume of more than 50% of the composite slab.

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[0059]

[0060] The advantage of this arrangement lies in the simplicity of the manufacturing process. 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 of between 35 and 85 and / or a slip resistance of at least 35. The assembly of the two concretes (resistant / absorbent) is carried out by adhesion, the absorbent concrete adhering to the concrete ensuring the resistance. 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 example embodiment illustrated in figures 11 and 14 The composite slab contains an insertion of hemp concrete into a low-carbon, high-albedo structural concrete. It has dimensions of 30 cm x 30 cm x 10 cm, Composition of the resistant visible layer:

[0061]

[0062] Composition of the insert visible on the absorbent surface: Hemp concrete based on hemp shiv, the central part of the hemp stem. Slab performance: Luminance (structural concrete) 72 Albedo (structural concrete) 0.425 Water absorption (% by mass) 15.1% Effusivity (J.m2. K AS l / 2) 1634 Capillary absorption (% of potentially absorbable water) 24.8%

[0063]

[0064] Example 2 - Composite slab according to the example illustrated in [Fig.5] The composite slab contains an insertion of hemp concrete into a low-carbon, high-albedo structural concrete. The slab has dimensions of 30 cm x 30 cm x 10 cm, the resistant concrete layer having a thickness of 4 cm while the absorbent concrete layer having

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[0073] a thickness of 6 cm. Composition of the resistant visible layer: Composition under non-visible absorbent layer: Hemp concrete based on hemp shiv, central part of the hemp stem. Slab performance: Example 3 - Composite slab according to the example illustrated in [Fig.7] The composite slab is made up of two layers: the surface layer ensuring the resistance of the product and a sub-layer (non-visible layer) of absorbent hemp concrete. The slab has a dimension of 30 cm x 30 cm x 10 cm, the resistant concrete layer having a thickness of 4 cm while the absorbent concrete layer having a thickness of 6 cm. Composition of the resistant visible layer: Composition under non-visible absorbent layer: Hemp concrete based on hemp shiv, central part of the hemp stem. Slab performance:

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

Claims

Claims

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

2. Composite slab (IA, IB, IC, 1D) made 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 have at least one area flush with the laying face.

3. Composite slab (IA, IB, IC, 1D) made 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 have at least one area flush with the face opposite the laying face.

4. Composite slab (IA, IB, IC, 1D) made 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) made 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 on the laying face at least and filled respectively with a concrete composition forming the non-structural part of concrete (3).

6. Composite slab (IA, IB, IC, 1D) made 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 of concrete (2) has a luminance value of between 35 and 85.

8. Composite slab (IA, IB, IC, 1D) made 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) made 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) made 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) made 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 CO2 eq / m3.

12. Composite slab (IA, IB, IC, 1D) made 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 plant fibers.

13. Composite slab (IA, IB, IC, 1D) made of concrete according to any one of claims 1 to 12, characterized in that the concrete of the non-structural part (3) comprises bio-sourced aggregates or aggregates with high water absorption chosen in a non-limiting manner from expanded clay aggregates, cellular concrete aggregates, textile chips.

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.

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