METHOD FOR FIRE PROTECTION OF MATERIAL

Description

[0001] The invention relates to a method for fireproofing materials. Previous art

[0002] The fireproofing of materials is commonly carried out using flame retardant additives including environmentally harmful and toxic compounds such as brominated or chlorinated compounds.

[0003] There is a rapidly growing demand for the use of alternative, non-toxic and environmentally friendly additives.

[0004] Geopolymers derived from mineral chemistry represent an ideal alternative; they possess intrinsic flame-retardant properties and do not require the use of toxic or environmentally harmful components in their manufacture. These geopolymers are prepared from a pozzolanic material such as metakaolin, which, when mixed with an activation solution containing an alkaline base and at least one silicate, dissolves, forming a viscoelastic suspension. This viscoelastic suspension then polymerizes at rest, hardening and thus forming a geopolymer.

[0005] This polymerization reaction is a geopolymerization reaction in that inorganic polymers are formed during the reaction. These inorganic polymers are essentially composed of silico-oxide (-Si-O-Si-O-), silico-aluminate (-Si-O-Al-O-), ferro-silico-aluminate (-Fe-O-Si-O-Al-O-) or alumino-phosphate (-Al-OPO-) motifs.

[0006] French patent FR2659963 discloses geopolymer materials intended for use in fire-resistant coatings.

[0007] French patent FR 2680194 discloses a method for thermally insulating a building element using an organic geopolymer mineral binder.

[0008] Patent EP2451758 discloses building units made from geopolymer cement. Detailed description of the invention

[0009] The invention relates to a method for fireproofing a material comprising the steps of: a) contacting said material with a viscoelastic suspension obtained by mixing a pozzolanic material with an alkaline activation solution comprising at least one soluble metal hydroxide in which the molar concentration of hydroxide ions in the activation solution is between 3 and 8 M; b) geopolymerization of said viscoelastic suspension; c) obtaining a flame-retardant material comprising a geopolymer.

[0010] Viscoelasticity refers to the property of materials that exhibit both viscous and elastic characteristics when deformed. Viscous materials resist shear flow and exhibit deformation that increases linearly with time when a stress is applied. Elastic materials deform when stressed and quickly return to their original state once the stress is removed. In rheology, the behavior of a linear viscoelastic material is thus intermediate between that of an ideal elastic solid, symbolized by a spring with modulus E (or G), and that of a Newtonian viscous liquid, symbolized by a viscosity damper. The elasticity of a material reflects its ability to store and release energy after deformation. The viscosity of a material reflects its ability to dissipate energy.

[0011] The viscoelastic behavior of the suspension is evident during aging, that is, when the suspension approaches hardening or, more precisely, the stage where it becomes viscoplastic. The rheological study of the viscoelastic suspension confirms the existence of a yield stress at the beginning of the measurement when the suspension is at rest. It also shows that the viscosity decreases under increasing shear rate. The rheological behavior of the viscoelastic suspension has a thixotropic phase defined by a yield stress, followed by a shear-thinning profile. After several hours in the container, this behavior becomes shear-thickening. In the first few hours after its production, the binder's rheology is non-Newtonian and viscoelastic.

[0012] "Fireproofing" refers to the treatment of a substance or material to reduce its flammability.

[0013] In one embodiment, the material fireproofing process according to the invention is characterized in that at least one soluble metal hydroxide is an alkali metal hydroxide.

[0014] Preferably at least one alkali metal hydroxide is chosen from the group consisting of sodium hydroxide and potassium hydroxide, alone or in combination.

[0015] In one embodiment, the material fireproofing process according to the invention is characterized in that said alkaline activation solution further comprises at least one silicate.

[0016] In one embodiment, the material fireproofing process according to the invention is characterized in that said at least one silicate comprises a soluble alkali metal oxide.

[0017] Preferably, at least one silicate comprising a soluble alkali metal oxide is chosen from the group consisting of sodium silicate and potassium silicate, alone or in combination.

[0018] In one embodiment, the material fireproofing process according to the invention is characterized in that the silicate concentration of said viscoelastic suspension is between 5% and 25% by mass.

[0019] In one embodiment, the material fireproofing process according to the invention is characterized in that the silicate concentration of said viscoelastic suspension is between 5% and 20% by mass.

[0020] In one embodiment, the material fireproofing process according to the invention is characterized in that the silicate concentration of said viscoelastic suspension is between 10% and 15% by mass.

[0021] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of pozzolanic material in said viscoelastic suspension is between 15% and 50% by mass.

[0022] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of pozzolanic material in said viscoelastic suspension is between 20% and 45% by mass.

[0023] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of pozzolanic material in said viscoelastic suspension is between 25% and 40% by mass.

[0024] In one embodiment, the material fireproofing process according to the invention is characterized in that said pozzolanic material is metakaolin.

[0025] The term "metakaolin" refers to a thermally dehydroxylated kaolinitic clay. In other words, it is a dehydroxylated alumina silicate with the general composition Al2O3, 2SiO2.

[0026] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one soluble metal hydroxide of said viscoelastic suspension is between 2% and 10% by mass.

[0027] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one soluble metal hydroxide of said viscoelastic suspension is between 2% and 8% by mass.

[0028] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one soluble metal hydroxide of said viscoelastic suspension is between 4% and 8% by mass.

[0029] In one embodiment, the material fireproofing process according to the invention is characterized in that said alkaline activation solution further comprises at least one hydrophobic agent selected from the group consisting of siliconates, silanes, siloxanes, and mixtures thereof.

[0030] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one hydrophobic agent of said viscoelastic suspension is between 1% and 7% by mass.

[0031] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one hydrophobic agent of said viscoelastic suspension is between 1% and 5% by mass.

[0032] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one hydrophobic agent of said viscoelastic suspension is between 2% and 4% by mass.

[0033] In one embodiment, the material fireproofing process according to the invention is characterized in that said alkaline activation solution further comprises at least one surfactant.

[0034] In one embodiment, the material flame retardant process according to the invention is characterized in that said alkaline activation solution further comprises at least one anionic surfactant selected from the group consisting of C8-C18-alkyl sulfates, C8-C18-alkyl ether sulfates, C8-C18-alkyl aryl sulfonic acids, C8-C18 fatty acids and mixtures thereof.

[0035] An "anionic surfactant" is defined as a surfactant that releases a negative charge in aqueous solution. The class of anionic surfactants is extensively described in the literature.

[0036] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one surfactant of said viscoelastic suspension is between 0.005% and 0.15% by mass.

[0037] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one surfactant of said viscoelastic suspension is between 0.005% and 0.075% by mass.

[0038] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one surfactant of said viscoelastic suspension is between 0.005% and 0.05% by mass.

[0039] In one embodiment, the material fireproofing process according to the invention is characterized in that the SiO2 / Al2O3 ratio of said viscoelastic suspension is between 2 and 5.

[0040] In one embodiment, the material fireproofing process according to the invention is characterized in that the SiO2 / Al2O3 ratio of said viscoelastic suspension is between 2.5 and 4.5.

[0041] In one embodiment, the material fireproofing process according to the invention is characterized in that the SiO2 / Al2O3 ratio of said viscoelastic suspension is between 3 and 4.

[0042] In one embodiment, the material fireproofing process according to the invention is characterized in that the density of the viscoelastic suspension in contact with said material is between 500 and 3000 Kg / m 3< .

[0043] In one embodiment, the material fireproofing process according to the invention is characterized in that the density of the viscoelastic suspension in contact with said material is between 750 and 2500 Kg / m 3< .

[0044] In one embodiment, the material fireproofing process according to the invention is characterized in that the density of the viscoelastic suspension in contact with said material is between 1000 and 2000 Kg / m 3< .

[0045] In one embodiment, the material fireproofing process according to the invention is characterized in that the density of the viscoelastic suspension in contact with said material is between 1250 and 1750 Kg / m 3< .

[0046] In one embodiment, the material fireproofing process according to the invention is characterized in that the contact is made by a technique chosen from the group consisting of impregnation, mixing, coating or layering.

[0047] The term "impregnation" refers to the action of a substance penetrating a material by spreading or diffusing within it.

[0048] The term "mixture" refers to the act of blending, putting together various substances, and uniting them into a whole.

[0049] The term "coating" refers to the process of applying a product to the surface of a substrate. The product can be applied in one or more successive layers. After coating, another surface can be placed on top, which can then also be coated, and the process can be repeated as many times as necessary. This technique is particularly useful for manufacturing composite materials.

[0050] In one embodiment, the material fireproofing process according to the invention is characterized in that said material is of a shape chosen from the group consisting of blocks, fragments, filaments or fibers, particles, alone or in combination.

[0051] The term "block" refers to a compact mass of something, in one piece, with little or no work done.

[0052] The term "fragments" refers to pieces of something that has been broken or torn apart, debris.

[0053] The term "fibers or filaments" refers to an element with an elongated or stretched shape.

[0054] By "particles" we mean very small parts of something.

[0055] In one embodiment, the material fireproofing process according to the invention is characterized in that said material is chosen from the group consisting of organic materials and inorganic materials, alone or in combination.

[0056] The term "organic" refers to anything derived directly or indirectly from living tissues or organisms, which always contain carbon. This definition includes organic molecules produced by petrochemicals through hydrocarbon cracking.

[0057] The term "inorganic" refers to something of mineral consistency.

[0058] In one embodiment, the material fireproofing process according to the invention is characterized in that said material is permeable or impermeable.

[0059] In one embodiment, the material fireproofing process according to the invention is characterized in that the contact of said material with said viscoelastic suspension is achieved by impregnation.

[0060] In one embodiment, the material fireproofing process according to the invention is characterized in that said impregnated material is permeable.

[0061] In one embodiment, the material fireproofing process according to the invention is characterized in that said impregnated permeable material is made of organic material.

[0062] In one embodiment, the material fireproofing process according to the invention is characterized in that said impregnated permeable material is made of inorganic material.

[0063] In one embodiment, the material fireproofing process according to the invention is characterized in that said impregnated permeable material is in block form.

[0064] In one embodiment, the material fireproofing process according to the invention is characterized in that said impregnated permeable material is in the form of a block of organic material.

[0065] In one embodiment, the material fireproofing process according to the invention is characterized in that said permeable material impregnated in block form with organic materials is a foam.

[0066] In one embodiment, the material fireproofing process according to the invention is characterized in that said permeable material impregnated in block form with organic materials is a polyurethane foam.

[0067] In one embodiment, the material fireproofing process according to the invention is characterized in that said impregnated permeable material is in the form of a block of inorganic material.

[0068] In one embodiment, the material fireproofing process according to the invention is characterized in that said impregnated permeable material is in the form of fragments.

[0069] In one embodiment, the material fireproofing process according to the invention is characterized in that said impregnated permeable material is in the form of fragments of organic materials.

[0070] In one embodiment, the material fireproofing process according to the invention is characterized in that said impregnated permeable material is in the form of fragments of inorganic materials.

[0071] In one embodiment, the material fireproofing process according to the invention is characterized in that said impregnated permeable material is in the form of filaments or fibers.

[0072] In one embodiment, the material fireproofing process according to the invention is characterized in that said impregnated permeable material is in the form of organic filaments or fibers.

[0073] In one embodiment, the material fireproofing process according to the invention is characterized in that said impregnated permeable material is in the form of inorganic filaments or fibers.

[0074] In one embodiment, the material fireproofing process according to the invention is characterized in that the contact of said material with said viscoelastic suspension is achieved by coating or layering.

[0075] In one embodiment, the material fireproofing process according to the invention is characterized in that the viscoelastic suspension is coated for a basis weight of 50 to 1500 g / m2.

[0076] In one embodiment, the material fireproofing process according to the invention is characterized in that the viscoelastic suspension is coated for a basis weight of 150 to 1000 g / m2.

[0077] In one embodiment, the material fireproofing process according to the invention is characterized in that the viscoelastic suspension is coated for a basis weight of 250 to 900 g / m2.

[0078] In one embodiment, the material fireproofing process according to the invention is characterized in that said coated material is in block form.

[0079] In one embodiment, the material fireproofing process according to the invention is characterized in that said coated material is in the form of a block of inorganic materials.

[0080] In one embodiment, the material fireproofing process according to the invention is characterized in that said coated material is in the form of a block of organic materials.

[0081] In one embodiment, the material fireproofing process according to the invention is characterized in that said coated material is in the form of fragments.

[0082] In one embodiment, the material fireproofing process according to the invention is characterized in that said coated material is in the form of fragments of organic materials.

[0083] In one embodiment, the material fireproofing process according to the invention is characterized in that said coated material is in the form of fragments of inorganic materials.

[0084] In one embodiment, the material fireproofing process according to the invention is characterized in that said coated material is in the form of particles.

[0085] In one embodiment, the material fireproofing process according to the invention is characterized in that said coated material is in the form of particles of organic materials.

[0086] In one embodiment, the material fireproofing process according to the invention is characterized in that said coated material is in the form of particles of inorganic materials.

[0087] In one embodiment, the material fireproofing process according to the invention is characterized in that said coated material is in the form of fibers or filaments.

[0088] In one embodiment, the material fireproofing process according to the invention is characterized in that said coated material is in the form of fibers or filaments of organic materials.

[0089] In one embodiment, the material fireproofing process according to the invention is characterized in that said coated material is in the form of fibers or filaments of inorganic materials.

[0090] In one embodiment, the material fireproofing process according to the invention is characterized in that the contact of said material with said viscoelastic suspension is achieved by mixing.

[0091] In one embodiment, the material fireproofing process according to the invention is characterized in that said mixed material is in the form of fragments.

[0092] In one embodiment, the material fireproofing process according to the invention is characterized in that said mixed material is in the form of fragments of organic materials.

[0093] In one embodiment, the material fireproofing process according to the invention is characterized in that said mixed material is in the form of fragments of inorganic materials.

[0094] In one embodiment, the material fireproofing process according to the invention is characterized in that said mixed material is in the form of particles.

[0095] In one embodiment, the material fireproofing process according to the invention is characterized in that said mixed material is in the form of particles of organic materials.

[0096] In one embodiment, the material fireproofing process according to the invention is characterized in that said mixed material is in the form of particles of inorganic materials.

[0097] In one embodiment, the material fireproofing process according to the invention is characterized in that said mixed material is in the form of fibers or filaments.

[0098] In one embodiment, the material fireproofing process according to the invention is characterized in that said mixed material is in the form of fibers or filaments of organic materials.

[0099] In one embodiment, the material fireproofing process according to the invention is characterized in that said mixed material is in the form of fibers or filaments of inorganic materials.

[0100] The organic materials used in the fireproofing process according to the present invention, whatever their forms, are advantageously bio-sourced.

[0101] The term "bio-based" refers to materials derived from renewable organic matter (biomass), of plant or animal origin. They can be used as raw materials in construction and decoration products, built-in furniture, and as building materials.

[0102] A non-exhaustive list of bio-based materials includes wood, cork, straw, hemp, cellulose wadding, recycled textiles, animal wool, glass wool, rock wool, polystyrene, cereal husks, miscanthus, flax, thatch, meadow grass, various passive waste such as feathers and industrial and / or agri-food grindings, etc.

[0103] Thus, at the end of the process, a completely natural fire-retardant material is obtained without chemical additives that are problematic for health.

[0104] In one embodiment, the material fireproofing process according to the invention is characterized in that it comprises, between steps a) and b), a shaping step.

[0105] In one embodiment, the material fireproofing process according to the invention is characterized in that the shaping step is carried out by a technique chosen from the group consisting of pressing, molding, extrusion.

[0106] The term "pressing" refers to a shaping process using a press.

[0107] The term "molding" refers to a process of obtaining an object by filling a mold with a substance that retains the shape of the mold after hardening or solidification.

[0108] The term "extrusion" refers to a shaping process that involves pushing material through a die.

[0109] In one embodiment, the material fireproofing process according to the invention is characterized in that the shaping step is carried out by pressing.

[0110] In one embodiment, the material fireproofing process according to the invention is characterized in that the shaping step is carried out by molding.

[0111] In one embodiment, the material fireproofing process according to the invention is characterized in that the shaping step is carried out by extrusion.

[0112] In one embodiment, the material fireproofing process according to the invention is characterized in that it includes, between steps b) and c), a solvent removal step.

[0113] In one embodiment, the material fireproofing process according to the invention is characterized in that the solvent is removed by drying.

[0114] In one embodiment, the material fireproofing process according to the invention is characterized in that the solvent is water.

[0115] In one embodiment, the material fireproofing process according to the invention is characterized in that it comprises, prior to step a), a step for manufacturing the viscoelastic suspension comprising the steps of: w) Dissolving at least one soluble metal hydroxide in aqueous solution; x) stirring and obtaining an activation solution; y) introducing a pozzolanic material into said activation solution; z) mixing and obtaining a viscoelastic suspension.

[0116] In one embodiment, the material flameproofing process according to the invention is characterized in that at step w) at least one soluble metal hydroxide is an alkali metal hydroxide.

[0117] Preferably at least one alkali metal hydroxide is chosen from the group consisting of sodium hydroxide and potassium hydroxide, alone or in combination.

[0118] In one embodiment, the material fireproofing process according to the invention is characterized in that the molar concentration of hydroxide ions of at least one soluble metal hydroxide in aqueous solution is between 5 and 10 M.

[0119] In one embodiment, the material fireproofing process according to the invention is characterized in that the molar concentration of hydroxide ions of at least one soluble metal hydroxide in aqueous solution is between 6 and 9 M.

[0120] In one embodiment, the material fireproofing process according to the invention is characterized in that the molar concentration of hydroxide ions of at least one soluble metal hydroxide in aqueous solution is between 7 and 8 M.

[0121] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of soluble metal hydroxide of said activation solution is between 5% and 20% by mass.

[0122] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of soluble metal hydroxide of said activation solution is between 5% and 15% by mass.

[0123] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of soluble metal hydroxide of said activation solution is between 5% and 10% by mass.

[0124] In one embodiment, the material fireproofing process according to the invention is characterized in that at step w) at least one silicate is added.

[0125] In one embodiment, the material fireproofing process according to the invention is characterized in that at step w) at least one silicate comprising a soluble alkali metal oxide is added.

[0126] The said silicate comprising a soluble alkali metal oxide has the formula SiO2, M2O, H2O with M being an alkali metal.

[0127] In one embodiment, the material fireproofing process according to the invention is characterized in that the M2O / SiO2 ratio of said activation solution is between 0.1 and 0.4.

[0128] In one embodiment, the material fireproofing process according to the invention is characterized in that the M2O / SiO2 ratio of said activation solution is between 0.15 and 0.35.

[0129] In one embodiment, the material fireproofing process according to the invention is characterized in that the M2O / SiO2 ratio of said activation solution is between 0.2 and 0.3.

[0130] Preferably, at least one silicate comprising a soluble alkali metal oxide is chosen from the group consisting of sodium silicate and potassium silicate, alone or in combination.

[0131] In one embodiment, the material fireproofing process according to the invention is characterized in that the silicate concentration of said activation solution is between 10% and 40% by mass.

[0132] In one embodiment, the material fireproofing process according to the invention is characterized in that the silicate concentration of said activation solution is between 10% and 30% by mass.

[0133] In one embodiment, the material fireproofing process according to the invention is characterized in that the silicate concentration of said activation solution is between 15% and 25% by mass.

[0134] In one embodiment, the material fireproofing process according to the invention is characterized in that at step w) at least one hydrophobic agent is added.

[0135] In one embodiment, the material fireproofing process according to the invention is characterized in that at least one hydrophobic agent is chosen from the group consisting of siliconates, silanes, siloxanes, and mixtures thereof.

[0136] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one hydrophobic agent of said activation solution is between 1% and 10% by mass.

[0137] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one hydrophobic agent of said activation solution is between 2% and 8% by mass.

[0138] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one hydrophobic agent of said activation solution is between 3% and 6% by mass.

[0139] In one embodiment, the material fireproofing process according to the invention is characterized in that at step w) at least one surfactant is added.

[0140] In one embodiment, the material flame retardant process according to the invention is characterized in that at least one surfactant is an anionic surfactant selected from the group consisting of C8-C18-alkyl sulfates, C8-C18-alkyl ether sulfates, C8-C18-alkyl aryl sulfonic acids, C8-C18 fatty acids and mixtures thereof.

[0141] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one surfactant of said activation solution is between 0.005% and 0.15% by mass.

[0142] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one surfactant of said activation solution is between 0.01% and 0.1% by mass.

[0143] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one surfactant in said activation solution is between 0.025% and 0.075% by mass.

[0144] In one embodiment, the material fireproofing process according to the invention is characterized in that at step w) at least one egg albumin powder is added.

[0145] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one egg albumin powder in said activation solution is between 0.1% and 3% by mass.

[0146] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one egg albumin powder in said activation solution is between 0.2% and 2% by mass.

[0147] In one embodiment, the material fireproofing process according to the invention is characterized in that the concentration of at least one egg albumin powder in said activation solution is between 0.3% and 1.2% by mass.

[0148] In one embodiment, the material fireproofing process according to the invention is characterized in that at least one egg albumin powder is a protein fraction extracted from deglucosylated egg albumin rich at 80%.

[0149] For example, egg albumin powder is an EAP-HWI powder (EGG ALBUMEN POWDER - HIGH WHIP INSTANT).

[0150] The addition of egg albumin powder makes it possible to obtain a viscoelastic suspension having a lower density, which is particularly advantageous for the implementation of the fireproofing process of the present invention.

[0151] In one embodiment, the material fireproofing process according to the invention is characterized in that the density of the viscoelastic suspension in contact with said material is between 250 and 2000 Kg / m3.

[0152] In one embodiment, the material fireproofing process according to the invention is characterized in that the density of the viscoelastic suspension in contact with said material is between 500 and 1500 Kg / m3.

[0153] In one embodiment, the material fireproofing process according to the invention is characterized in that the density of the viscoelastic suspension in contact with said material is between 800 and 1000 Kg / m3.

[0154] In one embodiment, the material fireproofing process according to the invention is characterized in that the water concentration of said activation solution is between 50% and 85% by mass.

[0155] In one embodiment, the material fireproofing process according to the invention is characterized in that the water concentration of said activation solution is between 55% and 80% by mass.

[0156] In one embodiment, the material fireproofing process according to the invention is characterized in that the water concentration of said activation solution is between 60% and 75% by mass.

[0157] In one embodiment, the material fireproofing process according to the invention is characterized in that the H2O / M2O ratio of said activation solution is between 6 and 16.

[0158] In one embodiment, the material fireproofing process according to the invention is characterized in that the H2O / M2O ratio of said activation solution is between 8 and 14.

[0159] In one embodiment, the material fireproofing process according to the invention is characterized in that the H2O / M2O ratio of said activation solution is between 10 and 12.

[0160] In the invention, the material fireproofing process according to the invention is characterized in that the molar concentration of hydroxide ions of said activation solution is between 3 and 8 M.

[0161] In one embodiment, the material fireproofing process according to the invention is characterized in that the molar concentration of hydroxide ions of said activation solution is between 4 and 7 M.

[0162] In one embodiment, the material fireproofing process according to the invention is characterized in that the molar concentration of hydroxide ions of said activation solution is between 5 and 6 M.

[0163] Using an activation solution with a lower molar concentration of hydroxide ions than the average commonly used activation solution makes the dissolution or chemical attack of pozzolanic material reasonably feasible on a construction site (short timeframes) while maintaining a reasonably acceptable alkalinity level for safety and health. This also allows for control of the solution's hygroscopic characteristics, and the formation of salts and carbonates is significantly reduced.

[0164] In one embodiment, the material fireproofing process according to the invention is characterized in that the Si / Al molar ratio of said activation solution is between 0.5 and 4.

[0165] In one embodiment, the material fireproofing process according to the invention is characterized in that the Si / Al molar ratio of said activation solution is between 0.75 and 3.5.

[0166] In one embodiment, the material fireproofing process according to the invention is characterized in that the Si / Al molar ratio of said activation solution is between 1 and 3. In one embodiment, the material fireproofing process according to the invention is characterized in that at step y) the pozzolanic material is metakaolin.

[0167] In one embodiment, the material fireproofing process according to the invention is characterized in that at step z) the Al 2 O 3 / M 2 O ratio of said viscoelastic suspension is between 0.7 and 1.3.

[0168] In one embodiment, the material fireproofing process according to the invention is characterized in that at step z) the Al 2 O 3 / M 2 O ratio of said viscoelastic suspension is between 0.8 and 1.2.

[0169] In one embodiment, the material fireproofing process according to the invention is characterized in that at step z) the Al 2 O 3 / M 2 O ratio of said viscoelastic suspension is between 0.9 and 1.1.

[0170] Ideally the Al 2 O 3 / M 2 O ratio of said viscoelastic suspension is equal to 1.

[0171] A fire-retardant polyurethane foam obtained by impregnation according to the process of the invention is also described.

[0172] In one embodiment, said fire-retardant polyurethane foam obtained by impregnation according to the process of the invention is characterized in that it comprises a geopolymer content of between 5 and 60 Kg / m 3< .

[0173] In one embodiment, said fire-retardant polyurethane foam obtained by impregnation according to the process of the invention is characterized in that it comprises a geopolymer content of between 10 and 50 Kg / m 3< .

[0174] In one embodiment, said fire-retardant polyurethane foam obtained by impregnation according to the process of the invention is characterized in that it comprises a geopolymer content of between 20 and 40 Kg / m 3< .

[0175] A fire-resistant agglomerate obtained by mixing according to the process of the invention is also described.

[0176] The term "agglomerate" refers to an artificial building material of regular geometric shape, resulting from the setting and hardening of a mixture of a binder and inert materials.

[0177] In one embodiment, the fire-retardant agglomerate obtained by mixing according to the process of the invention is characterized in that it comprises a geopolymer content of between 30 and 130 Kg / m 3< .

[0178] In one embodiment, the fire-retardant agglomerate obtained by mixing according to the process of the invention is characterized in that it comprises a geopolymer content of between 50 and 100 Kg / m 3< .

[0179] In one embodiment, the fire-retardant agglomerate obtained by mixing according to the process of the invention is characterized in that it comprises a geopolymer content of between 60 and 90 Kg / m 3< .

[0180] A fire-retardant composite material obtained by coating according to the process of the invention is also described.

[0181] The term "composite material" refers to a material formed from several elementary components whose combination gives the whole properties that none of the components taken separately possesses.

[0182] In one embodiment, the fire-retardant composite material obtained by coating according to the process of the invention is characterized in that it comprises a geopolymer weight of between 500 and 1500 g / m².

[0183] In one embodiment, the fire-retardant composite material obtained by coating according to the process of the invention is characterized in that it comprises a geopolymer weight of between 700 and 1000 g / m².

[0184] In one embodiment, the fire-retardant composite material obtained by coating according to the process of the invention is characterized in that it comprises a geopolymer weight of between 800 and 900 g / m².

[0185] A fireproof construction unit obtained by the process according to the invention is also described.

[0186] The term "building unit" refers to any element that can be used in the construction of a building, for example a plate, a beam, a brick, etc.

[0187] A geopolymer comprising the following is also described: 80% to 98% by mass of polymerized pozzolanic material; 1% to 7% by mass of hydrophobic agent; 0.005% to 0.15% by mass of surfactant; characterized in that it has a Si / Al ratio between 1 and 3. Examples Example 1: Viscoelastic suspension formulations

[0188] Table 1: Formulation of a viscoelastic suspension from a 100% Na basic activation solution. Components % of dry matter Pozzolanic material 1 Metakaolin 31,75 Activation solution 2A Sodium hydroxide 5,67 2B sodium silicate 13,38 Other components 3 Potassium methyl silicone hydrophobic agent Silres BS16 3,54 4 Anionic surfactants Empicol XHL-300 0,033 Total WATER 45,63 % Table 2: Formulation of a viscoelastic suspension from a basic K activation solution Components % of dry matter Pozzolanic material 1 Metakaolin 33,6% Activation Solution 2A Potassium hydroxide 7,18 2B sodium silicate 5,19 2C Potassium silicate 7,34 Other components 3 Potassium methyl silicone hydrophobic agent Silres BS16 3,51 4 Anionic surfactants Empicol XHL-300 0,035 Total WATER 43,15 % Example 2: Example of manufacturing a viscoelastic suspension according to the invention :

[0189] In a disperser equipped with a 55 mm diameter deflocculating wheel, the following is introduced under agitation at 300 rpm: an alkaline solution of potassium hydroxide at 7.5M; potassium and sodium silicates; potassium methyl siliconate Silres BS16; surfactant Empicol XHL-300.

[0190] Metakaolin is introduced by sprinkling into this composition to obtain a viscoelastic suspension.

[0191] The viscoelastic suspension is mixed at a speed of 1600 rpm for approximately 40 minutes.

[0192] Preferably, under gentle stirring at 300 rpm, the viscoelastic suspension is cooled to a temperature of approximately 20°C.

[0193] Example 3: Fire-retardant bonded wood chip agglomerate :

[0194] Viscoelastic suspension density used: 1500 Kg / m 3< .

[0195] Geopolymer content present in the agglomerate after drying: 70.6 Kg / m 3< . Operating procedure:

[0196] The wood chips are poured into a Kenwood mixer bowl, under rotary mixing (motor running at low speed), water is added by spraying, then the viscoelastic suspension is added gradually in a thin stream so that the distribution of liquids is as uniform as possible.

[0197] A small amount of the mass of shavings is poured into a beaker and the whole thing is pressed using another beaker nested inside the first.

[0198] Fire test: A pellet of pressed and bound wood chips, as described previously, is 3 cm thick and 9 cm in diameter. The tip of a blowtorch flame is placed and centered on the pellet.

[0199] A very slow pyrolytic combustion is observed, without visible flames or smoke. There is no open combustion with a flame, nor any flame propagation when the blowtorch flame is applied to the pellet. No combustion fumes are observed. Readings taken with an IR pyrometer on the back of the pellet stabilize at approximately 60°C, with the front exposed to the flame. minutes Temperature (back) Temperature (face) 15 56 Between 500 and 1000 20 59 Between 500 and 1000 25 59-60 Between 500 and 1000 30 59-60 Between 500 and 1000 35 59-60 Between 500 and 1000 Flame out 36 59-60 250 45 59-60 175

[0200] Table 3: Monitoring of the temperature on the back of a pellet according to example 3, as a function of time. Example 4: Fire-retardant polyurethane foam:

[0201] Viscoelastic suspension density used: 1500 Kg / m 3< .

[0202] Geopolymer content present in polyurethane foam after drying: 31 Kg / m 3< .

[0203] Untreated polyurethane foams were impregnated with viscoelastic suspension and left to dry for one week at room temperature.

[0204] The impregnation of the foams was carried out by dipping them directly into a paint vat containing the viscoelastic suspension, then the excess was removed by crushing the polyurethane foams.

[0205] Following drying, a fire test was carried out by burning the treated foam as well as the untreated foam.

[0206] For untreated polyurethane foam, combustion is observed with the formation of flames, droplets and fumes.

[0207] For polyurethane foam treated with a binder according to the invention, no combustion of the foam or release of fumes is observed. Example 5: Composite material:

[0208] Viscoelastic suspension density used: 1500 Kg / m 3< .

[0209] Weight of geopolymer present in the composite material after drying: 840 g / m².

[0210] A viscoelastic suspension was used to form a more mechanically resistant composite with fire-resistant properties.

[0211] Fiberglass was applied between two layers of viscoelastic suspension.

[0212] The composite thus produced can be used in the form of panels for electrical network casing, thus providing protection against vandalism but also against fires. Example 6: Fireproofing a material by coating it with a viscoelastic suspension :

[0213] Viscoelastic suspension density used: 1500 Kg / m 3< .

[0214] Geopolymer weight after drying: 297.2 g / m²

[0215] A viscoelastic suspension is applied with a brush onto wooden boards (1 or 2 coats).

[0216] A fire test is then carried out after the viscoelastic suspension has dried. Panels coated with the viscoelastic suspension and one uncoated panel are burned. Results :

[0217] Neutral wood plate after 5 minutes of combustion. The wood cracked under the heat, and when the blowtorch was stopped, a flame continued to burn for a few seconds.

[0218] Wooden panel with 1 layer of viscoelastic suspension coating after 5 min combustion. The wood cracked under the heat, no flames were observed when the blowtorch was stopped.

[0219] Wooden panel with 2 layers of viscoelastic suspension coating after 5 min combustion. Only the surface was damaged; no cracking of the wood or flames were observed. Example 7: Fireproofing of bio-based materials according to the process of the invention and comparison with untreated materials or materials that have undergone chemical fireproofing treatments

[0220] Cellulose wadding was coated with a viscoelastic suspension and then left to dry. It was then subjected to combustion by the flame of a blowtorch for 180 seconds. When the blowtorch was switched off, no flames were observed.

[0221] Cellulose wadding that has undergone a fire-retardant chemical treatment (5% boron salts) is subjected to combustion by a blowtorch flame for 180 seconds. When the blowtorch is switched off, smoke is observed and the flame continues to spread.

[0222] Expanded polystyrene was coated with a viscoelastic suspension and then left to dry. It was then subjected to combustion by a blowtorch flame for 180 seconds. When the blowtorch was switched off, no flames, droplets, or smoke were observed; the material had not been damaged during combustion.

[0223] A sheep's wool panel was coated with a viscoelastic suspension and then left to dry. It was then subjected to combustion by the flame of a blowtorch for 180 seconds. When the blowtorch was switched off, no flames, droplets, or smoke were observed.

[0224] An untreated, fire-resistant sheep's wool panel is subjected to combustion by a blowtorch flame for 180 seconds. When the blowtorch is switched off, flames are observed, along with the presence of smoke and droplets of polyethylene, which serves as a binder for the wool; combustion continues.

Claims

1. A process for fireproofing materials comprising the steps of: a) placing a material in contact with a viscoelastic suspension obtained by mixing a pozzolanic material with an alkaline activation solution comprising at least one soluble metal hydroxide, the viscoelastic suspension having a molar concentration of hydroxide ions of between 3 and 8 M; b) geopolymerizing the viscoelastic suspension; and c) obtaining a fireproofed material comprising a geopolymer.

2. The process for fireproofing materials according to claim 1 characterized in that the concentration of pozzolanic material in the viscoelastic suspension is between 15% and 50% by mass.

3. A process for manufacturing a viscoelastic suspension according to any of the previous claims characterized in that the SiO2 / Al2O3 ratio of the viscoelastic suspension is between 2 and 5.

4. The process for fireproofing materials according to any of the previous claims characterized in that the pozzolanic material is metakaolin.

5. The process for fireproofing materials according to any of the previous claims characterized in that the concentration of metal hydroxide in the viscoelastic suspension is between 2% and 10% by mass.

6. The process for fireproofing materials according to any of the previous claims characterized in that the manner of contact is performed by a technique chosen from the group consisting of impregnation, mixing, coating or layering.

7. The process for fireproofing materials according to any of the previous claims characterized in that the material is in the form of blocks, fragments, filaments or fibers, particles, alone or in combination.

8. The process for fireproofing materials according to any of the previous claims characterized in that the material is an organic material, an inorganic material, alone or in combination.

9. The process to fireproof materials according to any of the previous claims characterized characterised in that it comprise prior to step a) a step of manufacturing the viscoelastic suspension comprising the steps of : w) setting in aqueous solution of at least one soluble metal hydroxide. x) agitating and obtaining an activation solution; y) introducing a pozzolanic material into the activation solution; z) mixing and obtaining a viscoelastic suspension.

10. The process to fireproof materials according to claim 9, characterised in that the molar concentration of hydroxide ions of the at least one soluble metal hydroxide in aqueous solution is between 5 and 10 M.