WO2022269204A1 - Concrete panel, method for manufacturing such a panel and mould for implementing the method - Google Patents

Abstract

The invention relates to a concrete panel (40) having a front face (41) configured to be visible and a rear face (42) opposite to the front face (41), the panel (40) comprising at least one concrete layer (30) and a salt layer (20), the salt layer (20) at least partially forming the front face (41). The invention further relates to a method for manufacturing such a panel and to a mould (10) for implementing the method

Description

Concrete panel, method of manufacturing such a panel and mold for implementing the method

The invention relates to a concrete panel.

It also relates to a method for manufacturing such a panel as well as a mold for implementing the method.

The invention relates more particularly to an embodiment of a panel for covering a wall or a ceiling.

A panel designates here an element of any type of outline and/or of any three-dimensional geometric shape. It can be for example a flat panel, as well as a curved panel, or comprising at least two sides inclined with respect to each other.

A concrete panel can be used for decorative purposes.

Such a panel is for example configured to be used as a facing for a building wall, whatever the shape of the wall to be coated.

For this, research has been carried out in order to give concrete different properties, in particular aesthetic properties, for example to give it different surface effects, and/or different colors.

In this context, according to a first aspect of the invention, a concrete panel is proposed, the panel comprising a front face, configured to be visible, and a rear face, opposite the front face, the panel comprising at least one layer of concrete and the panel being characterized in that it further comprises a layer of salt, and in that the layer of salt forms at least partly the front face.

Unexpectedly, the use of an element that is conventionally associated with concrete pathologies proved interesting.

Indeed, salt, such as sodium chloride (NaCl) traditionally leads to corrosion of the metal reinforcements which can reinforce a concrete, which generally causes a change in the volume of the reinforcements and incidentally a bursting of the concrete.

Here, however, the salt makes it possible to produce an interesting random visual effect on the surface appearance (the front face), in particular at least one effect among a relief, texture, or even coloring effect. Depending on the nature of the concrete and the salt, different phenomena of diffusion, solubilization or crystallization of the salt can occur, which can induce one of said interesting random visual effects.

In addition, it is thus possible to take advantage of a possibly natural material, salt. Furthermore, since salt has hygroscopic properties, in humid conditions, such a panel comprising a surface layer of salt can thus have hydrophilic and/or hygroscopic properties.

It is thus possible to give a concrete panel a regulating effect of ambient humidity, depending on the concrete and salt chosen, and on an atmosphere of an environment in which the panel will be installed.

In addition, the presence of salt in a relatively large quantity in the concrete makes it possible to proceed with an antibacterial effect, making it possible to clean up the environment of the panel.

In an exemplary embodiment, the panel comprises between 0.2 kg and 1 kg of salt per square meter of apparent surface of the panel, preferably between 0.5 kg/m ² and 0.7 kg/m ² , for example around 0.6 kg/m ² .

The visible surface of the panel is for example its front face.

The thickness of such a panel is for example between 0.5 cm and 30 cm, or even preferably between 0.5 cm and 10 cm, in particular between 1 cm and 3 cm, typically 1.8 cm.

Such a panel therefore comprises a relatively large quantity of salt compared to the concrete so that the salt is visible, and for example decorative.

The salt thus used as a filler makes it possible to reduce the quantity of concrete in a panel. In addition, it appeared that the salt then forms sufficiently solid agglomerates for the panel to retain sufficient structural capacity to at least form a facing panel, i.e. decorative.

Such a panel leaves the possibility of making it with a very small thickness, i.e. for example a thickness of less than 3 cm. In length and width, such a panel measures for example between 20 cm×20 cm and 90 cm×90 cm, typically 30 cm×60 cm.

In an exemplary embodiment, the salt comprises sodium chloride (NaCl), for example at least 75% sodium chloride, even at least 80%, even preferably at least 90% sodium chloride. NaCI salt crystals are naturally cubic in shape. They are at least translucent and white in color.

Sodium chloride, for example, has a deliquescence point at 75% relative humidity at 25°C.

In an exemplary embodiment, the front face of the panel comprises at least one colorant.

For example, the dye comprises at least one of: a pigment, an oxide, for example a mineral oxide, an organic compound, for example a microorganism biomass, for example a microalgae.

A possible microalgae is, for example, Dunaliella salina. Such a microalga makes it possible to provide a pink tint.

According to other examples, the dye can be an iron oxide, or micronized vegetable charcoal.

According to a particular example, the salt comprises the at least one colorant.

The dye is thus mixed with the salt, in the mass. According to another particular example, the concrete comprises the at least one colorant.

The dye is thus mixed with the concrete, in the mass.

The concrete can be made from any type of concrete usually used to make a panel, in particular a facing panel, in particular for a wall or a ceiling. In an exemplary embodiment, the concrete comprises a mortar or a micromortar. In one embodiment, the concrete comprises fibers, i.e. it is a fiber-reinforced concrete.

The fibers include, for example, fibers of PVA (polyvinyl alcohol), or equivalent, i.e. preferably insensitive to a corrosive effect of the salt used in the panel.

Preferably, metal fibers are to be avoided.

In an exemplary embodiment, the panel further comprises a treatment layer, for example a water-repellent and/or oil-repellent treatment layer, the treatment layer being applied to at least the front face. Such a treatment layer is preferably translucent, or even transparent, to allow the front face formed at least in part by the salt to be viewed.

Such a panel thus has a choice of smooth, matte or shiny surface, depending on the materials (concrete and salt) chosen, and the optional addition of a treatment layer. The front face and the rear face of the panel thus define between them an edge of the panel, having a non-zero thickness.

As described below, it is thus possible to arrange the panel in a vertical position, at least for example during a drying step. Also proposed, according to a second aspect of the invention, is a method for manufacturing a concrete panel, in particular a concrete panel as described above.

According to an example of implementation, the method comprises:

A step of supplying a panel mould; - A salt disposal step at the bottom of the mould; and

A step of pouring concrete into the mould, over the salt.

The mold is for example a mold as described later.

It appeared that placing the salt at the bottom of the mold makes it possible to better control a distribution of the efflorescences of salt crystals, and to limit mixing between the salt and the concrete.

Depending on the amount of salt placed at the bottom of the mould, different effects of color, salt-concrete marble, homogeneity or, conversely, irregularity in the distribution of the salt crystals can be produced.

Such an arrangement also makes it possible to remain closer to traditional concrete setting kinetics.

Indeed, the salt can have a retarding or accelerating effect (depending on the concentrations introduced); it appeared that by depositing the salt at the bottom of the mould, its effect on the setting speed of the concrete is lessened and/or controlled.

A content of the mould, here the salt and the concrete, thus comprises a part in contact with the bottom of the mould, which is then configured to form the front face of the panel, and a part consisting of a free surface, which is then configured to form the back face of the panel.

The part forming the rear face of the panel, which is intended to subsequently allow the panel to be attached, for example to a wall or a ceiling, can then be more easily mainly made up of concrete, therefore possibly less weakened by the presence of salt.

Concrete and/or salt can be prepared according to the desired panel.

In an advantageous mode of implementation, the method includes a step of setting the concrete, during which the concrete adheres to the salt. Such a stage preferably lasts at least 12 hours, for example around 24 hours, depending on the concrete and the salt chosen.

In an interesting mode of implementation, the process includes a step of unmoulding the panel, after the step of setting the concrete. A part of the panel in contact with the bottom of the mold then forms the front face of the panel, and the free surface before demolding forms the rear face of the panel.

According to a particular mode of implementation, the step of unmolding includes a step of straightening the mold still containing the panel, then a step of removing the mold while keeping the panel straightened. Considering that the mold is filled while being horizontal, a straightening designates here a pivoting of the mold aimed at orienting it more vertically, or even bringing it into a vertical position.

As at this stage the concrete of the panel has set but which is not yet dry, such removal of the panel from the mold makes it possible to limit manipulation of the panel alone, at least to remove it from the mould, and therefore to limit the risk of damage to the panel, for example a risk of cracking or fracture.

Also, as described below, it is best to dry the panel in an upright position whenever possible. Straightening the panel while it is still in the mold therefore protects it. In an advantageous mode of implementation, the method comprises a step of drying the panel, preferably the stripped panel.

Drying time varies depending on temperature and weather conditions.

In an interesting example of implementation, the drying step includes a step of positioning the panel on edge, i.e. in a vertical position. Such a positioning facilitates for example a more uniform drying of the panel. The drying step includes for example different parameters, for example depending on the crystallization conditions of the salt, a targeted drying rate, a humidity of the concrete, for example a relative humidity influencing a crystallization scheme. According to an interesting option, the drying step includes a ventilation step. In an advantageous mode of implementation, the method includes a finishing step.

According to a possible option, the finishing step comprises a sanding step and/or a very soft polishing step. According to another conceivable option, the finishing step comprises a step of applying a preparation configured to form a treatment layer, for example a water-repellent and/or oil-repellent treatment layer, for example on at least the front face of the sign. For example, the application step includes a step of spraying the preparation configured to form the treatment layer.

According to another mode of implementation, the method comprises a step of coloring the front face of the panel.

For example, the coloring step includes a step of mixing a dye in the salt before placing it in the mould.

For example, the coloring step includes a step of mixing a dye into the concrete before pouring it into the mould.

For example, the coloring step includes a step of spraying a colored product on the front face of the panel. The colored product comprises for example a colored salt water, i.e. a salt water comprising a dye.

The dye comprises for example a pigment, an oxide, for example an inorganic oxide (for example an iron oxide), and/or an organic compound, such as for example a microorganism biomass, for example a microalgae. A possible microalgae is, for example, Dunaliella satina.

Such a microalga makes it possible to provide a pink tint.

Charcoal can also be used.

According to yet another mode of implementation, the method further comprises a rectification step. For example, the rectification step may include a step of applying a coating locally.

For example, the rectification step may include a step of spraying salt water, in particular water saturated with salt, preferably the same salt as that constituting the panel. Using the same salt as the panel facilitates recrystallization at a desired location in the panel.

This also makes it possible to create patterns in relief with respect to the front face of the panel which forms its visible face. Finally, there is also proposed, according to a third aspect of the invention, a mold for manufacturing a concrete panel, in particular a panel as described previously.

Such a mold is in particular configured to implement the method as described previously.

According to a particularly interesting example of embodiment, the mold is a flexible mold, that is to say that it is relatively flexible.

Preferably, the mold also has a low roughness.

A low roughness denotes for example here a roughness of less than 30 μm, or even 20 μm, or even 10 μm, or even 2 μm.

Such a mold can for example be made of silicone or any similar or equivalent material.

In the context of the present invention, a flexible mould, in particular made of silicone, has proven to be sufficiently robust and particularly convenient for producing a concrete panel containing salt.

In particular, such a mold appeared very convenient for implementing the demolding step in the upright position described above.

For example, such a mold comprises a bottom of any shape depending on the desired panel shape, and a peripheral wall surrounding the bottom. The peripheral wall has for example a height comprised between 0.5 cm and 20 cm, for example between 2 cm and 15 cm.

The height of the peripheral wall defines for example a depth of the mould.

Its other dimensions depend on the format of the panel to be obtained.

The invention, according to an exemplary embodiment, will be well understood and its advantages will appear better on reading the detailed description which follows, given by way of indication and in no way limiting, with reference to the appended drawings in which: FIG. 1 represents a mold manufacturing a concrete panel according to an exemplary embodiment of the invention; FIG. 2 illustrates a step of placing salt at the bottom of the mold of FIG. 1 to produce a concrete panel according to an embodiment of the invention; FIG. 3 illustrates a step of pouring concrete onto the salt in the mold to produce the panel; FIG. 4 then illustrates a step for unmolding the panel; and FIG. 5 illustrates the panel obtained, placed in a vertical position, for example for a drying step according to one embodiment of the invention. The present invention relates to a concrete and salt panel.

A particularly interesting method for manufacturing such a panel is illustrated in Figures 1 to 5, and involves for example using a mold 10 as shown in Figure 1. The mold 10 includes a bottom 11 delimited by an outline 12.

The bottom 11 can have any type of shape, depending on a desired shape for the panel to be produced.

Here the bottom 11 has a rectangular shape.

The bottom 11 is surrounded by a peripheral wall 13, which extends from the bottom 11, perpendicular to the bottom 11 or in a flared manner (i.e. with clearance) depending on the needs, and it ends with a free edge 15.

The bottom 11 and the peripheral wall 13 thus define a filling volume of the mold into which a product can be poured, for example a liquid, pasty or powdery product, in particular here salt and concrete, to produce the panel. The peripheral wall 13 has a height 14, which is defined between the bottom 11 and its free edge 15.

The height 14 is for example between 0.5 cm and 20 cm, depending on a desired panel thickness.

In the present exemplary embodiment, the mold is a flexible mold, made of a material that is relatively flexible and possibly of low roughness, such as, for example, silicone.

An equivalent material, in particular in terms of low rigidity or roughness, is however possible.

Such a material thus makes it possible to produce a mold with a very low roughness surface, that is to say possibly with an absolute roughness of less than 20 μm, or even possibly less than 10 μm, or even 2 μm.

A low roughness makes it possible in particular to facilitate removal from the mold to subsequently unmold the panel, and also to have little influence on an appearance of a surface of the panel, in particular on a front face of the panel as described below. To manufacture a salt and concrete panel, a manufacturing method according to the invention then comprises, for example, a step E1 of supplying a panel mold, for example as described here in connection with Figure 1.

FIG. 2 then illustrates a step E2 of placing the salt 20 at the bottom of the mould. During this step, salt 20 is distributed at the bottom of the mold 10. Provision is thus made to produce the front face of the panel, that is to say the decorative face intended to be visible, at the bottom of the mould.

The salt is here distributed evenly at the bottom of the mould.

According to another example not shown, it could be arranged using a stencil system, for example in order to secure and/or facilitate the placement of the salt.

The distribution of salt can be homogeneous, or with denser areas of salt as shown here, depending on the desired effect.

For example, the salt here essentially comprises sodium chloride, which gives it a white color and translucency. FIG. 3 then illustrates a step E3 of pouring a concrete 30 into the mold, over the salt.

Beforehand, if necessary, local reservations can be planned to then add a fixing system to the panel, in order to facilitate its hanging on a wall or a ceiling for example. Before pouring the concrete 30, the concrete is mixed, respecting the quantities of cement, aggregates, any colorant and water until a fluid paste and homogeneous mixture are obtained. Fibers can be incorporated at the end of mixing if necessary.

Possibly after a few minutes of waiting (for example approximately 5 minutes), the concrete 30 is poured on the salt 20 at the bottom of the mould.

According to an interesting implementation example, the concrete 30 is poured on the salt 20 starting from one end of the mould, as shown schematically in FIG. 3, and moving on the wave formed by the flow to a opposite end of the mold 10. The casting takes place at a distance from the bottom 11 of the mold which is for example between 20 cm and 60 cm, or even between 20 cm and 30 cm with respect to the bottom 11.

An optional additional reinforcement (for example a bar, a metal trellis, a bracket, or other) can be envisaged according to the needs and the intended use of the panel. Such reinforcement is then preferably immersed in the concrete. The mold is for example arranged horizontally, possibly using a level controller such as a spirit level, in order to control a thickness of the panel, preferably so as to form a rear face of the panel, produced by a free surface of the concrete cast in the mold, parallel to the front face formed by at least the salt in contact with the bottom 11 of the mold. After pouring the concrete, the panel can optionally be covered with a polyane to prevent the concrete from drying too quickly.

The panel is preferably thus kept in place in the mold for a few hours, for example approximately 24 hours after the pouring of the concrete; thus, during this time, the salt adheres to the concrete and the concrete achieves sufficient strength to handle the panel.

FIG. 4 then illustrates a step E4 of unmolding the panel 40 thus formed. Thanks to the setting of the concrete, when the panel 40 has sufficient resistance to be manipulated while limiting the risk of breaking it by moving it, the panel 40 can be removed from the mould.

For this, in the present embodiment, the mold 10 is for example straightened, then is removed from the panel 40.

Thanks to the flexibility of the mold 10, as described in connection with Figure 1, little bending stress is applied to the panel 40 during its demolding, further reducing the risk of damage or breakage of the panel 40.

It is therefore preferable not to handle the front side, containing the salt.

Once removed from the mould, any excess salt that may not have adhered to the concrete can be brushed away meticulously, preferably without rubbing the surface of the panel.

FIG. 5 then illustrates a step E5 for drying the panel 40. The drying time varies according to the temperature and the climatic conditions.

If several panels 40 are intended to be juxtaposed, it is preferable to produce them under the same drying conditions to promote consistency in the aesthetic appearance of the panels.

For example, the panel is considered dry when the color of the concrete is uniform and efflorescence forms over the entire surface of the panel.

The drier the ambient conditions, the lighter the panel (greater amount of white efflorescence). Conversely, the slower the drying, the darker the panel remains.

According to an interesting characteristic of the present invention, the panel is dried on edge, in a vertical position.

Such positioning promotes uniform drying which minimizes possible deformation and/or warping of the panel.

During drying, it is preferable to avoid any object/wedge/protection coming into contact with the front face of the panel to limit the risk of formation of a stain or a difference in color which could appear. at this location. The method can then comprise various steps, for example a rectification step.

The rectification step can for example include a patching step and/or an aesthetic repair step of the front face of the panel. For example, a thin plaster is selected, for example with fast setting and little shrinkage.

After hardening, the coating can be easily scraped, sanded, or even colored locally. It can also be worked with a sponge or brush depending on the desired effect. In order to increase the resemblance between a repair (the addition of plaster) and the surface of the panel (the front face), salt water can be applied locally, for example with a sponge, on the surface of the repair and around to reveal efflorescences and salt crystals.

The method may also include a finishing step. For example, in order to homogenize an aspect of the panel, a sanding (for example with grain 200 to 500) and/or a very soft polishing can be envisaged.

The method may also include a step for protecting the surface of the panel, for example a step for applying to the front face of the panel a preparation configured to form a treatment layer, for example a water-repellent and/or oil-repellent treatment layer. .

If necessary, such a preparation can be applied in two layers by spraying.

Figure 5 also illustrates the panel 40 in salt and concrete obtained according to an example of implementation of the invention. The panel 40 has a front face 41, which was previously the face in contact with the bottom 11 of the mold 10, and a rear face 42, opposite the front face.

The front face 41 and the rear face 42 define between them an edge 44 which has a thickness 43, which is considered constant here.

As shown in Figure 5, the panel 40 here comprises a layer of salt 20, which forms the front face 41, and a layer of concrete 30 which here forms the rear face 42.

The panel 40 in salt and concrete has for example a desired color, because the concrete and/or the salt can be tinted on demand, on the surface on the front face 41, or in the mass.

At least the front face 41 of the panel can have a smooth and shiny surface appearance. The distribution of the salt on the surface, on the front face 41 , can be homogeneous, with zones more or less dense in salt, or evenly distributed over the surface of the panel.

Claims

1. Concrete panel (40), the panel (40) comprising a front face (41), configured to be visible, and a rear face (42), opposite the front face (41), the panel (40) comprising at least one layer of concrete (30) and the panel (40) being characterized in that it further comprises a layer of salt (20), and in that the layer of salt (20) at least partially forms the front side (41). 2. Panel (40) according to claim 1, characterized in that the salt (20) comprises sodium chloride (NaCl). 3. Panel (40) according to any one of claims 1 or 2, characterized in that the front face (41) of the panel (40) comprises at least one colorant, the colorant comprising at least one of: a pigment, a oxide, for example a mineral oxide, an organic compound, for example a microorganism biomass, for example a microalga. 4. Panel (40) according to any one of claims 1 to 3, characterized in that it comprises between 0.2 kg and 1 kg of salt per square meter of the front face of the panel, a thickness of the panel being between 0.5 cm and 30 cm. 5. Panel (40) according to any one of claims 1 to 4, characterized in that it comprises a treatment layer, for example a water-repellent and/or oil-repellent treatment layer, the treatment layer being applied to at least the front side. 6. Panel (40) according to claim 5, characterized in that the treatment layer is translucent, even transparent, to allow visualization of the front face formed at least in part by the salt. 7. A method of manufacturing a concrete panel (40) according to any one of the preceding claims, the method comprising: A step (E1) of providing a panel mold (10); A step (E2) of placing the salt (20) at the bottom of the mold (10); and A step (E3) of pouring the concrete (30) into the mold (10), over the salt (20). 8. Method according to claim 7, comprising a step of setting the concrete (30), during which the concrete (30) adheres to the salt (20). 9. Method according to claim 8, comprising a step of demoulding (E4) of the panel (40), after the step of setting the concrete (30). 10. Method according to claim 9, in which the step (E4) of demolding comprises a step of straightening the mold (10) containing the panel (40), then a step of removing the mold while keeping the panel straightened. 11. Method according to any one of claims 7 to 10, comprising a drying step (E5) of the panel (40), the drying step (E5) comprising a step of positioning the panel (40) on edge (44 ), i.e. in a vertical position. 12. Method according to any one of claims 7 to 11, comprising a finishing step which comprises a step of applying a preparation configured to form a treatment layer, for example a water-repellent treatment layer and/or oil repellent, for example on at least the front face of the panel. 13. The method of claim 12, wherein the step of applying includes a step of spraying the preparation configured to form the treatment layer. 14. Method according to any one of claims 7 to 13, comprising a rectification step, the rectification step comprising a step of spraying salt water, in particular water saturated with salt. 15. Mold (10) configured to implement a method according to any one of claims 7 to 14, the mold (10) being a flexible mold, for example made of silicone.