Insulating building element

Abstract

The invention relates to a construction element comprising two facing walls so as to provide between them at least one cavity, said at least one cavity being at least partially filled by an insulating material comprising flakes of mineral or vegetable wool or cellulosic materials, bound by a hardened mineral binder.

Description

Title of the invention: Insulating building element

[0001] The invention relates to the field of building construction. It relates more particularly to obtaining building elements having good thermal insulation properties.

[0002] It is known to fill cavities made in building elements, such as walls or parts of walls, with insulating materials, such as mineral wool or foams, inorganic (e.g. cement foams) or organic (e.g. polyurethane foams).

[0003] These various solutions are not, however, without drawbacks. The filling of cavities with insulating material is not always homogeneous, leading to the creation of thermal bridges and therefore to a degradation of thermal insulation performance. These inhomogeneities can occur over time or during the transport of building elements to the construction site, in the case of prefabricated elements. For example, mineral wool-based materials can tend to settle, and shrinkage is sometimes observed in inorganic foams. Organic foams sometimes exhibit poorly controlled expansion during installation. Furthermore, some known solutions are not well suited to automation.

[0004] The invention aims to overcome these drawbacks by proposing a more efficient solution, with simpler and faster implementation, possibly automated.

[0005] To this end, the invention relates to a construction element comprising two facing walls so as to provide between them at least one cavity, said at least one cavity being at least partially filled by an insulating material comprising flakes of mineral or vegetable wool or cellulosic materials, bound by a hardened mineral binder.

[0006] The invention also relates to a method for obtaining such a building element, comprising mixing with water a composition comprising: - a powdered mineral binder and - flakes of mineral or vegetable wool or cellulosic materials, then the deposit of the resulting mixture in the cavity.

[0007] The use of a composition comprising mineral or vegetable wool flakes or cellulosic materials, and a powdered mineral binder, to insulate cavities makes it possible to overcome the aforementioned drawbacks. The invention ensures good adhesion of the insulating material to the walls (in particular, but not exclusively, to concrete walls), and good cohesion of the coating even for the significant thicknesses generally required by the targeted insulating performance, good resistance to the environment and aging, as well as good mechanical properties, particularly in compression, for a reduced carbon impact and good thermal insulation properties.

[0008] Preferably, at least 50%, in particular at least 60%, or even at least 80%, and even particularly preferably the entire volume of the or each cavity is filled by the insulating material.

[0009] After mixing the composition with water and allowing the mineral binder to harden, the resulting insulating material comprises mineral or plant-based wool flakes, or cellulosic materials, bonded together by a hardened mineral binder. The powdered mineral binder present in the composition becomes pasty after mixing with water, before hardening. The term "binder" therefore covers both the powdered binder present in the composition and the final hardened binder in the insulating material. The following details apply to both the composition and the insulating material.

[0010] Preferably, the insulating material comprises mineral or plant-based wool flakes bonded with a hardened mineral binder. Particularly preferred, the insulating material comprises mineral wool flakes bonded with a hardened mineral binder.

[0011] Mineral wool is preferably selected from glass wool, slag wool and rock wool. Mineral wool fibers preferably have a chemical composition comprising 30 to 75% by weight of SiO2, 5 to 40% by weight of CaO+MgO, 0-20% by weight of Na2O+K2O, 0-30% by weight of Al2O3 and 0-15% by weight of Fe2O3.

[0012] The use of glass wool generally allows for better thermal insulation performance, particularly due to a lower density.

[0013] Glass wool is generally formed by electric or flame melting of a mixture of powdered raw materials and cullet (recycled glass), followed by fiberization, in particular by internal centrifugation using a fiber-forming plate. The fibers of glass wool preferably have a chemical composition comprising 50-75% SiO2, 12-20% Na2O+K2O, 5-20% CaO+MgO, 0-8%, in particular 0-3% Al2O3 and 2-10% B2O3 (the percentages being by weight).

[0014] Rock wool and slag wool are generally formed by melting raw materials in the form of blocks and / or briquettes in a cupola furnace, or by electric melting or by submerged burners of powdered materials, followed by fiberization by external centrifugation using a plurality of rotors. Rock wool fibers preferably have a chemical composition comprising 30-50% SiO2, 10-26% Al2O3, 15-40% CaO+MgO, 0-5% Na2O+K2O and 3-15% Fe2O3. Slag wool fibers preferably have a chemical composition comprising 30-45% SiO2, 5-18% Al2O3, 30-60% CaO+MgO and 0-3% Na2O+K2O. Percentages are by weight.

[0015] Mineral wool is generally made up of interwoven vitreous fibers. As a rule, the mineral wool used does not contain an organic binder. However, it may contain one when the loose fill comes from recycled construction or factory waste, for example, obtained by grinding mineral wool panels. The loose fill may be blown-in wool flakes, which do not normally contain an organic binder, but may nevertheless contain organic additives, for example, silicone or an antistatic agent. These additives are notably sprayed onto the mineral wool during the fiber-laying process.

[0016] Vegetable wool comprises vegetable fibers preferably selected from the group consisting of lignocellulosic fibers, cellulosic fibers and cotton fibers. The lignocellulosic fibers are preferably selected from wood fibers, hemp fibers, flax fibers, sisal fibers, cotton fibers, jute fibers, coconut fibers, raffia fibers, abaca fibers, cereal straw, rice straw and mixtures thereof.

[0017] The term "flakes" refers to pieces formed from agglomerates (or clusters) of intertwined fibers of a certain size or dimension. It is essential that the composition and coating include the fibers in flake form and not as dispersed individual fibers or as fibers organized into sheets, grids, fabrics, or nonwovens, in order to achieve good thermal insulation properties. The insulating material is therefore distinct from a fiber-reinforced coating or mortar, which does not exhibit insulating properties.

[0018] The mineral or plant-based wool flakes in the composition and / or the coating are preferably between 1 and 10 cm in size, particularly between 2 and 8 cm, or even between 3 and 7 cm. Flakes that are too small result in denser coatings, and therefore less thermally insulating ones. The flakes can be obtained and their size adjusted, in particular, using a carding machine. The flakes can be larger in the composition if the spraying machine is capable of reducing their size before spraying.

[0019] The powdered mineral binder is preferably a hydraulic binder. In the final insulating material, the mineral binder is then obtained by hardening a hydraulic binder.

[0020] The hydraulic binder is preferably chosen from the group consisting of Portland cements, belitic cements, aluminous cements, sulfoaluminous cements, pozzolanic mixture cements, slags, fly ash, metakaolins, hydraulic lime, calcium sulfate sources, and mixtures of two or more of these hydraulic binders. The calcium sulfate source is in particular chosen from gypsum, anhydrite, hemihydrate, and mixtures thereof.

[0021] The binder may in particular consist of Portland cement, in particular of the CEM type I or CEM II.

[0022] According to another embodiment, the binder comprises (in particular consists of) a mixture of Portland cement and a source of calcium sulfate. The presence of a source of calcium sulfate particularly improves the fire resistance properties and accelerates the setting of the binder. Its carbon footprint is also reduced compared to Portland cement. The proportion of the calcium sulfate source in this binder is preferably between 2 and 20% by weight, in particular between 5 and 15% by weight.

[0023] According to another embodiment, the binder comprises (in particular consists of) a mixture of sulfoaluminate cement and a calcium sulfate source. The binder then preferably comprises a setting accelerator, for example a lithium salt. The proportion of calcium sulfate source in this binder is preferably between 2 and 20% by weight, in particular between 5 and 15% by weight.

[0024] According to yet another embodiment, the binder comprises (or consists of) a mixture of Portland cement, aluminous cement, and a source of calcium sulfate. The binder may also comprise a setting accelerator, for example, a lithium salt. Such a binder allows for faster final hardening. In this embodiment, the weight proportions of the constituents in the binder are preferably as follows: 65 to 90% Portland cement, 5 to 20% aluminous cement, and 2 to 15% of a source of calcium sulfate.

[0025] In general, the presence of Portland cement allows for good mechanical performance, particularly in terms of compressive strength, and also enables the achievement of high pH levels, which have been shown to enhance the effectiveness of water-repellent agents. The addition of a lime source to the aforementioned binders has also proven beneficial in this respect.

[0026] The binder may also consist of a source of calcium sulfate, allowing good fire resistance properties, but at the expense of mechanical and thermal insulation properties.

[0027] Alternatively, the mineral binder may be a clay binder.

[0028] The composition (and therefore the insulating material) may include other constituents.

[0029] It may in particular include lightweight fillers, in particular selected from perlite, vermiculite, expanded glass beads, expanded polystyrene beads, cenospheres, expanded silicates, aerogels and mixtures thereof.

[0030] The composition advantageously comprises redispersible polymer powders. The polymer is preferably based on one or more monomers selected from vinyl esters (in particular vinyl esters of Cl-Cl5 carboxylic acids such as vinyl acetate), (meth)acrylates (in particular of C1-C10 alcohols), vinyl aromatics, alkenes (for example, ethylene), dienes, and ha- Vinyl lignin. These polymers improve the mechanical strength of the insulating material without affecting its thermal insulation properties. Therefore, the insulating material preferably contains such a polymer.

[0031] The composition (and therefore the insulating material) advantageously comprises thickening agents, which also improve the mechanical strength of the insulating material without affecting its thermal insulation properties, and provide better cohesion. The thickening agent is preferably a cellulose ether.

[0032] The composition (and therefore the insulating material) may also include surfactants, in particular to facilitate the wetting of the fibers by water during the coating application process. Sodium dodecyl sulfate is one advantageous surfactant.

[0033] The composition (and therefore the insulating material) may further include mineral or vegetable oils, in order to reduce dust emissions, in particular when the binder contains a source of calcium sulfate such as gypsum.

[0034] The weight content of mineral or plant wool or cellulosic materials is preferably between 50 and 90%, and in particular between 55 and 85%, relative to the combined weight of mineral or plant wool or cellulosic materials and mineral binder, or even relative to the total weight of the composition or insulating material. Given the low density of the mineral or plant wool flakes compared to the binder, the mineral or plant wool constitutes a very significant portion by volume, thus achieving good thermal insulation properties.

[0035] In the composition or in the insulating material, the weight content of mineral binder is preferably between 10 and 50%, in particular between 15 and 45%, relative to the cumulative weight of mineral or vegetable wool or cellulosic materials and mineral binder, or even relative to the total weight of the composition or insulating material.

[0036] In the case of slag wool, the mass proportion of wool relative to the binder preferably varies from 70:30 to 90:10. In the case of glass wool, the mass proportion of wool relative to the binder preferably varies from 50:50 to 70:30.

[0037] The composition and / or insulating material preferably comprises 50 to 90% (in particular 55-85%) by weight of mineral (or vegetable) wool, 10 to 50% (in particular 15-45%) by weight of mineral binder, relative to the cumulative weight of mineral (or vegetable) wool and mineral binder, or even relative to the total weight of the composition or insulating material.

[0038] The total content of any additives is normally less than 40%, or even 30%, 20%, or 10%, or greater than 0.1%, always expressed as a percentage of the total weight of mineral or vegetable wool (or cellulosic materials) and mineral binder. It is preferably no more than 5% for redispersible polymer powders and thickeners, and no more than 2% for oils. In other words, the total weight proportion of mineral or vegetable wool (or cellulosic materials) and mineral binder in the composition or insulating material is preferably at least 70%, in particular at least 80% and even at least 90%.

[0039] The contents indicated above apply to both the composition and the insulating material.

[0040] The composition is mixed with water and the resulting mixture is then deposited in the cavity.

[0041] The mixture is preferably deposited by spraying. Preferably, the composition (generally in dry form) is conveyed to a spray nozzle, and the water is added as early as possible at the nozzle outlet. Advantageously, a spraying machine is used, having a central conduit through which the composition is sprayed, around which is arranged at least one orifice, or in particular a plurality of orifices, through which the water is sprayed. The mixture of the composition and the water is then carried out at the nozzle outlet, before the mixture reaches the cavity.

[0042] The quantity of water (by weight) relative to the quantity of composition is preferably between 0.2 and 1.5, particularly between 0.5 and 1.4, or even between 0.7 and 1.2. The quantity of water must be sufficient for the setting and hardening of the binder. It should be adjusted taking into account that the mineral or plant-based wool will absorb some of the water. If the quantity of water added is too low, the composition will not adhere sufficiently to the surfaces and will detach.

[0043] The total flow rate of dry matter (mineral or vegetable wool, cellulosic materials, mineral binder and any solid additives) is preferably between 1 and 10 kg / min, in particular between 2 and 8 kg / min. The water flow rate is preferably between 5 and 10 L / min. The deposition rate is, for example, between 0.1 and 5 L / s, in particular between 0.5 and 3 L / s, or even between 0.8 and 1.5 L / s.

[0044] The density of the insulating material is preferably between 20 and 250 kg / m³, in particular between 50 and 200 kg / m³. The thermal conductivity of the insulating material is preferably between 35 and 60 mW / mK. When the mineral wool is rock wool or slag wool, this density is preferably between 100 and 200 kg / m³, with a thermal conductivity ranging in particular from 37 to 60 mW / mK. When the mineral wool is glass wool, the density of the insulating material is preferably between 50 and 150 kg / m³, in particular between 60 and 100 kg / m³, or even between 65 and 85 kg / m³, for thermal conductivities ranging in particular from 35 to 40 mW / mK.

[0045] The mechanical resistance of the insulating material is excellent, with resistances ranging in particular from 5 to 20 kPa in tension, from 5 to 60 kPa in bending (in particular from 40 to 60 kPa with slag or rock wool) and from 20 to 110 kPa in compression (in particular from 90 to 110 kPa with slag or rock wool).

[0046] The building element is preferably a wall or part of a wall. The lateral dimensions of the building element are preferably between 15 cm and 3 m, in particular between 20 cm and 2.5 m. By way of example, the building element, in particular the wall, may have a length of 2 m and a height of 2.5 m. The thickness of the cavity (i.e. the distance separating the walls) is preferably between 5 and 50 cm, in particular between 10 and 40 cm, or even between 15 and 30 cm.

[0047] The building element can be manufactured directly on the building construction site.

[0048] Preferably, however, the building element is a prefabricated element intended to be transported to the building construction site. The excellent cohesion between the walls and the insulating material allows, on the one hand, for transport without any reduction in the thermal insulation performance of the element (due to the absence of settling of the insulating material) and, on the other hand, for cutting to be carried out on the construction site, prior to assembly.

[0049] The walls of the building element can be made of various materials, including concrete blocks (bricks, blocks, stones, rubble, etc.), concrete or mortar, or even plaster, wood, oriented strand board (OSB), raw earth-based materials, etc. The two walls can be made of the same material or of different materials. The walls are generally flat and parallel to each other, but other geometries are of course possible, particularly when they are produced by additive manufacturing.

[0050] According to a preferred embodiment, the deposition of the insulating material, in particular the projection of the mixture, is carried out in a cavity already formed.

[0051] The process may therefore include a preliminary step of constructing the walls (i.e., before depositing the mixture in the cavity or cavities formed by said walls). The walls can be constructed using any known method. Examples include the assembly of concrete blocks (stones, rubble, bricks, blocks, etc.) or the pouring of concrete walls between two formwork halves. In a preferred method, the walls are constructed by additive manufacturing, also known as "3D printing," of mortar or concrete. This technique makes it possible, in particular, to obtain a wide variety of geometries. When the walls are made of concrete or mortar, the insulating material can be deposited while the walls are still fresh, or conversely, after they have hardened.

[0052] In this embodiment, the deposit can be made through the opening formed by the opposing walls. For example, it is made from above, with the walls arranged vertically. Alternatively, the deposit can be made through at least one opening in at least one of the walls.

[0053] Regardless of the embodiment, the deposition of the mixture, in particular the projection of the mixture, is preferably carried out by means of a robot, and is in particular automated. The projection nozzle is then carried by a mobile arm or gantry controlled by a computer. This method is particularly preferred in combination with the construction of the walls by additive manufacturing. It is thus possible to automate the entire manufacturing of the structural element.

[0054] The following non-limiting examples illustrate the invention and its advantages.

[0055] In the examples, the projected composition comprised 66.8% blown glass wool flakes marketed by the Applicant under the name Com-blissimo, 29.9% CEM I 52.5R cement, 3.3% hemihydrate, plus an addition of 0.41% cellulose ether (tylose) and 1.66% mineral oil (percentages by weight). The blown glass wool comprised 0.1 to 0.4% water-repellent agent (silicone), 1 to 2% mineral oil, and 0.2% antistatic agent, these agents being dispersed on the fibers.

[0056] In a first series of tests, the composition was sprayed so as to fill from above cavities delimited by mortar walls printed by an additive manufacturing technique, measuring 20 cm wide, 20 cm high and 20 cm thick. The dry material flow rate was 2 to 2.5 kg / min and the water flow rate was 5 to 5.5 L / min.

[0057] The insulating materials obtained had densities ranging, according to the tests, from 65 to 85 kg / m³ for thermal conductivities ranging from 37 to 70 mW / mK

[0058] The insulating material samples exhibited the following mechanical properties: - compressive strength: 26 kPa (for a density of 65 kg / m3) and 37 kPa (for a density of 85 kg / m3) - Tensile strength: 11 kPa (for a density of 65 kg / m3) - Flexural strength: 6 kPa (for a density of 65 kg / m3) and 18 kPa (for a density of 85 kg / m3).

[0059] In a second series of tests, the composition was projected into cavities delimited by wooden walls, 1 m wide, 2 m high and 20 cm thick, with dry matter flow rates of 3 to 3.5 kg / min and water flow rates of 5.0 to 6.0 L / min.

Claims

Demands

1. A building element comprising two facing walls so as to provide between them at least one cavity, said at least one cavity being at least partially filled by an insulating material comprising mineral or vegetable wool flakes or cellulosic materials, bound by a hardened mineral binder.

2. Construction element according to claim 1, wherein the insulating material comprises mineral or vegetable wool flakes bonded by a hardened mineral binder.

3. Construction element according to the preceding claim, wherein the mineral wool is selected from glass wool, slag wool and rock wool.

4. A building element according to any one of the preceding claims, wherein the mineral or vegetable wool flakes have a size between 1 and 10 cm.

5. A building element according to any one of the preceding claims, wherein the mineral binder is obtained by hardening a hydraulic binder, in particular selected from the group consisting of Portland cements, belitic cements, aluminous cements, sul-foaluminous cements, pozzolanic mixture cements, slags, fly ash, metakaolins, hydraulic lime, calcium sulfate sources and mixtures of two or more of these hydraulic binders.

6. A building element according to any one of the preceding claims, comprising 50 to 90% by weight of mineral or vegetable wool or cellulosic materials and 10 to 50% by weight of mineral binder, relative to the cumulative weight of mineral or vegetable wool or cellulosic materials and mineral binder.

7. A building element according to any one of the preceding claims, which is a wall or part of a wall.

8. A method for obtaining a building element according to any one of the preceding claims, comprising mixing with water a composition comprising: - a powdered mineral binder and - flakes of mineral or vegetable wool or cellulosic materials, and then depositing the resulting mixture in the cavity.

9. A method according to the preceding claim, wherein the mixture is deposited by projection, the composition being conveyed to a projection nozzle, and water being added at the earliest at the nozzle outlet.

10. A method according to any one of claims 8 or 9, wherein the deposition of the mixture is carried out in a cavity already formed.

11. Method according to the preceding claim, comprising a preliminary step of constructing the walls, in particular by additive manufacturing of mortar or concrete.

12. A method according to any one of claims 8 to 11, wherein the deposition of the mixture is carried out by means of a robot.