New formulation for low-carbon construction binder, preparation process and construction materials

Abstract

The invention relates to a low-carbon construction binder formulation comprising, in dehydrated form, a raw clay matrix and a deflocculating agent. It also relates to a construction binder, a process for preparing this construction binder, and a construction material comprising the construction binder according to the invention. Abstract figure: FIGURE 1

Description

Title of the invention: New formulation for low-carbon construction binder, preparation process and construction materials

[0001] The invention relates to the field of construction materials, and more particularly to binders that can be used in construction. The invention concerns a formulation for a construction binder. The invention also relates to a method for preparing a construction binder, the construction binder itself, and the use of such a binder in the production of construction materials. Previous technique

[0002] Cement is the second most consumed resource in the world, with more than 4 billion tons of material produced each year worldwide, and this consumption is constantly increasing, driven by the growing demand for housing and infrastructure.

[0003] Cement is a binder, generally hydraulic, which, when mixed with water, hardens and sets. After hardening, cement retains its strength and stability, even when exposed to water. A wide variety of cements are used worldwide. However, all conventional cements contain clinker, with the percentage varying from 5% for some blast furnace cements to a minimum of 95% for Portland cement, which is currently the most widely used cement in the world.

[0004] Clinker is produced by firing a mixture composed of approximately 80% limestone and 20% aluminosilicates (such as clays). This firing process, known as clinkerization, takes place at a temperature exceeding 1200°C, and such a cement production process therefore involves high energy consumption. Furthermore, the chemical conversion of limestone into lime also releases carbon dioxide. Consequently, the cement industry generates approximately 8% of global CO2 emissions. Faced with this challenge, industry and researchers are exploring ways to reduce the impact of carbon dioxide emissions generated by the cement industry.

[0005] One initial solution led to the creation of a cement plant operating on a combination of waste-based alternative fuels and technologies related to the capture and storage of carbon emitted during cement production, in order to achieve zero-emission status. However, these solutions are not yet available on an industrial scale and require substantial investment.

[0006] The preferred approach involves research into substitutes for Portland cement, which is far too energy-intensive. Indeed, the development of alternative construction binders, requiring less energy consumption for their production would make it possible to lower the energy footprint of the entire construction sector (Maddalena, et al, “Can Portland cement be replaced by low-carbon alternative materials? A study on the thermal properties and carbon emissions of innovative Cements”, Journal of Cleaner Production 186; 2018; 933-942).

[0007] For example, a new hydraulic binder similar to Portland cement but containing secondary constituents such as ash formed during coal combustion in power plants has been proposed. However, the secondary constituents (ash, pozzolana, blast furnace slag) generally represent a maximum of 35% of the mixture, and this composite Portland cement then contains at least 50% clinker. This remains too high a clinker content to constitute a truly low-carbon alternative to Portland cement.

[0008] Hydraulic binders or cements based on metakaolin have also been proposed. Metakaolin is a dehydroxylated aluminum silicate with the general composition Al₂Si₂O₇. It is a largely amorphous dehydration product of kaolinite, with the general formula Al₂(OH)₄Si₂O₅, which exhibits strong pozzolanic activity. Generally speaking, the pozzolanic activity of a material can be defined as the ability of a material, lacking binding properties, to react chemically with calcium hydroxide at room temperature in finely divided form and in the presence of moisture to form compounds possessing binding properties. Kaolinitic clays are widely available in the Earth's crust, and heat treatment (e.g., 600 to 800°C for a short time, known as "flash heating") leads to the dehydroxylation of the kaolinite crystal structure to yield metakaolin.The mixture of lime or sodium hydroxide and metakaolin during cement hydration induces a pozzolanic reaction. This reaction improves the binding properties of metakaolin-based cements. Due to these properties, metakaolin-based construction materials have been proposed, including flash-treated metakaolin combined with sodium hydroxide, as described in document FR3034094.

[0009] Furthermore, the use of uncalcined kaolinite or, more broadly, raw clay matrix has been proposed for cements with lower carbon footprints (NA Hadi, “Geo Polymerization of Kaolin and Metakaolin Incorporating NaOH and High Calcium Ash,” Earth Science Research Vol. 5, No. 1; 2016). However, these cements, as described in document FR3016376, either exhibited insufficient physical properties, such as improved mechanical strength, reduced capillary absorption, or reduced permeability to liquids, or required the addition of a portion of Portland cement to achieve acceptable mechanical properties.

[0010] Thus, there is a need for new construction binder formulations with a low carbon footprint while exhibiting mechanical properties at least equivalent to or even superior to the mechanical properties of cements commonly used in the field of construction, such as CEM I, CEM II, CEM III, CEM IV and CEM V cements defined by the NF EN 197-1 standard. [Technical problem]

[0011] The invention therefore aims to overcome the drawbacks of the prior art. In particular, the invention aims to provide a construction binder formulation that makes it possible, on the one hand, to obtain a construction material with mechanical properties at least equivalent to Portland cement, and on the other hand, to improve the comfort of the inhabitants compared to concrete made from Portland cement.

[0012] The invention further aims to provide a method for manufacturing a construction binder that reduces greenhouse gas emissions, such as carbon dioxide emitted during the preparation of such a binder, while preserving the suitable mechanical characteristics of said binder for its use in the construction field. The invention also relates to the use of a construction binder for the production of building elements capable of improving occupant comfort compared to conventional concrete, and in particular the hygrothermal properties of buildings. [Brief description of the invention]

[0013] To this end, the invention relates to a construction binder formulation comprising, in dehydrated form, a raw clay matrix and a deflocculating agent.

[0014] Thus, this dehydrated formulation is intended to replace, totally or partially, conventional cements such as Portland cement, lime, or calcium aluminate cement (CSA). As will be shown later, this formulation achieves mechanical performance identical to Portland cement (class C 25 / 30) while reducing greenhouse gas emissions by 30 to 85%, and more generally by about 50%.

[0015] In addition, the presence of a raw clay matrix allows for better hygrothermal transfer and therefore better cooling properties for the building using a binder from this formulation.

[0016] According to other optional features of the formulation: - the raw clay matrix contains at least one mineral species selected from: Kaolinite, Illite, Smectite, Bentonite, Chlorite, Montmorillonite, muscovite, hallocyte, sepiolite, attapulgite, vermiculite, and so-called interstratified clays, which are complex combinations of several clays, are all minerals used in cement formulations. The presence of one or more of these minerals in the binder formulation allows for the production of a cement, and more broadly, a construction material with good mechanical properties—mechanical properties equivalent to those of a construction material containing Portland cement. Preferably, the raw clay matrix contains at least one mineral selected from among kaolinite, illite, smectite, and bentonite. - It comprises at least 80% by weight of raw clay matrix, preferably between 80 and 99.5% by weight, and more preferably between 90 and 99% by weight. Such a quantity of raw clay matrix improves the mechanical properties of materials constructed from this formulation. - The deflocculating agent is selected from: - a non-ionic surfactant such as a polyethylene ether, - an anionic agent such as an anionic agent selected from: alkylaryl sulfonates, amino alcohols, carbonates, silicates, fatty acids, humates (e.g. sodium humates), carboxylic acids, lignosulfonates (e.g. sodium lignosulfonates), polyacrylates, phosphates or polyphosphates such as sodium hexametaphosphate, sodium tripolyphosphate, sodium orthophosphate, carboxymethylcelluloses and mixtures thereof; - a polyacrylate such as a polyacrylate selected from sodium polyacrylate or ammonium polyacrylate; - an amine such as an amine selected from: 2-amino-2-methyl-l-propanol; mono-, di- or triethanolamine; isopropanolamines (l-Amino-2-propanol, diisopropanolamine and triisopropanolamine) and N-alkylated ethanolamines; or - their mixtures.

[0017] These deflocculating agents allow good dispersion of clays and are suitable for clay matrices that can be used in construction. - The deflocculating agent represents at least 0.5% by weight of the raw clay matrix, preferably between 0.5 and 20% by weight of the raw clay matrix, and more preferably between 1 and 10% by weight. Such a concentration improves the mechanical properties of materials constructed from this formulation. - it includes: • 80% to 99.5% by weight of raw clay matrix, and • 0.5% to 20% by weight of deflocculating agent.

[0018] Such a construction binder formulation makes it possible, in the case where such a formulation is used in coupling with an activation composition, to obtain mechanical properties equivalent to Portland cement.

[0019] The invention further relates to a construction binder comprising the constituents of the construction binder formulation according to the invention and an activation composition. The activation composition enables the construction binder to impart its desired mechanical properties and, in particular, to bind the clay sheets together.

[0020] According to other optional characteristics of the construction binder: - The activation composition is an alkaline activation composition. The alkaline composition may, for example, include a compound having a pKa greater than or equal to 10, more preferably greater than or equal to 12, and even more preferably substantially equal to 14. The activation composition includes metal oxides. In particular, the metal oxides are present at a concentration of at least 2% by weight of the composition, preferably at least 5% by weight, and even more preferably at least 10% by weight. Such a concentration improves the mechanical properties of materials constructed from this formulation. - the metal oxides are selected from: iron oxides such as FeO, Fe3O4, Fe2O3, Fe2O3, alumina A12O3, manganese(II) oxide MnO, titanium(IV) oxide TiO2 and their mixtures. - The activation composition contains cement. The cement may, for example, be a CEM I type cement. - it includes: • 50% to 89% by weight of raw clay matrix, • 15% by weight of deflocculating agent, and • from 10% to 49% by weight of activation composition.

[0021] These quantities make it possible to obtain mechanical properties equivalent to Portland cement while having a much lower carbon footprint.

[0022] The invention further relates to a method for preparing a construction binder comprising the following steps: - Prepare a clay suspension comprising at least a raw clay matrix, a deflocculating agent, and water. - Add an activation composition to the clay suspension; said activation composition may be an alkaline activation composition and / or contain metal oxides, and - Mix together to obtain a building binder.

[0023] According to other optional features of the process: - it includes a step of mixing the clay suspension in order to obtain a deflocculated clay suspension and the activation composition is added after the mixing step. - the construction binder comprises at least 50% by weight of raw clay matrix, preferably between 50 and 80% by weight. - the deflocculating agent represents at least 0.25% by weight of the construction binder, preferably at least 0.5% by weight of the construction binder, more preferably between 0.5 and 10% by weight of the construction binder. - The activation composition is present at a content of at least 10% by weight of binder. For example, metal oxides are present at a content of at least 10% by weight of binder.

[0024] The invention further relates to a construction material such as a mortar, a coating, a plaster, an insulator, a lightweight concrete, a prefabrication element, comprising the construction binder according to the invention.

[0025] The construction material according to the invention may further comprise one or more fillers, the fillers being, for example, selected from mineral or plant-based fillers. The fillers may be any fillers known to those skilled in the art in the field of construction materials. In particular, they may be selected from recycled or non-recycled aggregates, powders, sand, gravel, crushed stone, and / or fibers. The fibers may, in particular, be fibers of plant origin such as sawdust, wood chips and fibers, straw, flax, perlite, cork, or hemp shives. Preferably, the construction material according to the invention further comprises fibers of plant origin.

[0026] The construction material may also contain pigments.

[0027] The construction material according to the invention may further comprise an expansive or foaming agent, such as aluminum powder.

[0028] According to another aspect, the invention relates to the use of the construction binder according to the invention, for the production of coating elements, in particular floor coverings, such as tiles, slabs, paving stones or borders, wall coverings, such as interior or exterior facade elements, facing tiles, cladding elements, or roof coverings of the tile type, for the production of extruded or molded construction modules, such as bricks, or for the production of various extruded shapes.

[0029] The invention relates to the use of the construction binder according to the invention, for the production of composite materials, such as prefabricated construction panels, prefabricated blocks such as door lintels or window, prefabricated wall elements, or any other prefabricated building element.

[0030] The invention relates to the use of the construction binder according to the invention, for the production of insulation modules, such as partition panels, or lightweight insulating construction modules (with a density of less than 1.5 kg / L, preferably less than 1.2 kg / L, preferably even less than 1.0 kg / L, preferably even less than 0.7 kg / L)

[0031] The invention relates to the use of the construction binder according to the invention, for the production by additive manufacturing, such as by means of a 3D printer, of construction elements, buildings or houses, or decorative objects.

[0032] The invention relates to the use of the construction binder according to the invention in the form of a two-component system with either on the one hand the constituents in solid form, and on the other hand the constituents in liquid form, or the constituents in the form of two pastes, for the production of sealant, glue or sealing mortar.

[0033] Other advantages and features of the invention will become apparent from the following description, given by way of illustrative and non-limiting example, with reference to the accompanying Figures:

[0034] [Fig. 1] represents a diagram of the process for preparing a construction binder according to the invention. [Description of the invention]

[0035] In the following description, the term "% by weight" in relation to the raw clay matrix, formulation, binder, or construction material should be understood as a proportion relative to the dry weight of the formulation, binder, or construction material. The dry weight corresponds to the weight before the addition of water, for example, necessary for the formation of a construction binder.

[0036] The term "Dehydrated" in the context of the invention refers to a formulation containing a reduced amount of water, for example, a water content of less than 20% by weight, preferably less than 10%, more preferably less than 5%, and for example, less than 1% by weight. The water content can be measured by any method known in the prior art. For example, it can be measured according to standard NF P 94 050 of September 1995, "Determination of the water content by weight of materials: Oven drying method."

[0037] The term "clay matrix" means one or more rock materials based on hydrated silicates or aluminosilicates with a lamellar structure, said clay matrix being composed of fine particles generally resulting from the alteration of silicates with a three-dimensional framework, such as feldspars. A clay matrix may thus comprise a mixture of such rock materials, which may, for example, consist of kaolinite, illite, smectite, bentonite, chlorite, and so on. vermiculite, metakaolin, or mixtures thereof. The term "raw clay matrix" refers, for the purposes of this invention, to a clay matrix that has not undergone a calcination step. In particular, it means that it has not been subjected to any prior heat treatment. For example, this corresponds to a clay matrix that has not been heated above 300°C, preferably above 200°C, and more preferably above 150°C. Indeed, the raw clay matrix may undergo a heating step requiring a temperature rise generally of approximately 150°C, but not a calcination step.

[0038] The term "flocculant agent" refers to any compound which, in aqueous suspension, will dissociate aggregates and colloids. Flocculant agents have, for example, been used in drilling or oil extraction to make clay more fluid and facilitate extraction or drilling.

[0039] The term "activation composition" means any composition whose function is to accelerate the dispersion of an aluminosilicate source promoting the formation of stable hydrates with low solubility and the formation of a compact structure with these hydrates, thereby increasing the mechanical resistance of materials incorporating such an activation composition.

[0040] The term "substantially equal" in the meaning of the invention corresponds to a value varying by less than 20% from the compared value, preferably by less than 10%, even more preferably by less than 5%.

[0041] The inventor has developed a new formulation for a construction binder which could advantageously, but not limited to, be used as a replacement for Portland cement, lime or CSA.

[0042] A formulation according to the invention, and more specifically a construction binder according to the invention, has the advantage of having a carbon footprint at least twice as low as most construction binders, or hydraulic binders, most commonly used in the world today (i.e., Portland cement). Indeed, a construction binder according to the invention is primarily composed of a clay matrix, also called a raw clay matrix, which has not undergone a calcination step, an energy-intensive step that also generates the emission of greenhouse gases, and more particularly carbon dioxide.

[0043] Furthermore, a construction formulation or binder according to the invention has a lower clinker content than equivalent products and, with equivalent mechanical properties, allows for a reduction in CO2 emissions and production costs.

[0044] Advantageously, as will be shown in the examples, a construction binder according to the invention allows the manufacture of construction materials having mechanical properties at least equivalent to Portland cement and far superior to "low carbon" materials, such as those described above.

[0045] Thus, according to a first aspect, the invention relates to a construction binder formulation comprising, in dehydrated form, a raw clay matrix and a deflocculating agent.

[0046] As mentioned, the use of a raw clay matrix helps to reduce the environmental impact of the construction binder.

[0047] Deflocculating agents have already been used with clays. This is particularly the case in pottery and ceramics, where the preparation of a slip in a liquid, undehydrated state may involve mixing a deflocculating agent with a clay matrix. This practice allows the clay to be fluidized so that only the fine particles are recovered and is neither intended nor suitable for the preparation of a construction binder.

[0048] Here, without being limited by theory, the deflocculating agent can position itself at the interface of the layers constituting the raw clay matrix and disrupt its structure. Thus, the use of a deflocculating agent will allow the obtaining, from the raw clay matrix, of a formulation comprising a disrupted raw clay matrix capable of forming, in the presence of an activation composition, a more efficient construction binder.

[0049] Such a formulation can be prepared extemporaneously or prepared on a production site and then possibly stored and transported to the construction site.

[0050] Thus, the invention relates, for example, to a construction binder formulation comprising a raw clay matrix and a deflocculating agent, which is stored and / or transported pending its mixing with an activation composition, thereby enabling the formation of a construction binder. In particular, the formulation can be stored in containers with a capacity of 0.5 L to 50 L.

[0051] We will present in detail the general and preferred characteristics of each of the constituents of the formulation according to the invention. Raw clay matrix

[0052] The raw clay matrix may, for example, comprise at least one mineral species selected from: Kaolinite, Illite, Smectite, Bentonite, Chlorite and Vermiculite.

[0053] Table 1 below presents the chemical characteristics of these mineral species.

[0054] [Tables 1] Matrix Clayey Raw Type of clay Composition Illite (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)] Smectite / M ontmorillonite (Na,Ca)o.3(Al,Mg)2Si4010(OH)2, n H2O Kaolinite Al2Si2O5(OH)4 Metakaolin Anhydrous Al2Si2O5(OH)4 Bentonite (Na,Ca)o.3(Al,Mg)2Si4010(OH)2

[0055] Preferably, a formulation according to the invention comprises at least 80% by weight of raw clay matrix, and more preferably at least 90% by weight of raw clay matrix. Indeed, the construction binder formulation according to the invention has the advantage of being able to contain a high quantity of raw clay matrix without altering the mechanical properties of the resulting construction materials.

[0056] Furthermore, preferably, a formulation according to the invention comprises at most 98% by weight of raw clay matrix, and more preferably at most 96% by weight of raw clay matrix. Indeed, the construction binder formulation according to the invention also includes at least one deflocculating agent, thereby limiting the proportion of raw clay matrix in the formulation.

[0057] Thus, in particular, a formulation according to the invention can comprise between 80 and 99.5% by weight of raw clay matrix, preferably between 90 and 99% by weight or between 80 and 98% by weight of raw clay matrix, more preferably between 85 and 97% by weight of raw clay matrix, and even more preferably between 90 and 96% by weight of raw clay matrix. Deflocculating agent

[0058] Many compounds can act as deflocculating agents and many are generally known to those skilled in the art.

[0059] In the context of the invention, the deflocculating agent is in particular a non-ionic surfactant such as a polyoxyethylene ether. The polyoxyethylene ether may, for example, be selected from: a poly(oxyethylene) lauryl ether.

[0060] The deflocculating agent can also be an anionic agent such as an anionic surfactant. In particular, the anionic agent can be selected from: alkylaryl sulfonates, amino alcohols, carbonates, silicates, fatty acids, humates (e.g. sodium humates), carboxylic acids, lignosulfonates (e.g. sodium lignosulfonates), polyacrylates, phosphates or polyphosphates such as sodium hexametaphosphate, sodium tripolyphosphate, sodium orthophosphate, carboxymethylcelluloses and mixtures thereof.

[0061] The deflocculating agent can also be a polyacrylate. It can then be selected, for example, from sodium polyacrylate and ammonium polyacrylate.

[0062] The deflocculating agent may also be an amine selected for example from: 2-amino-2-methyl-l-propanol; mono-, di- or triethanolamine; isopropanolamines (l-Amino-2-propanol, diisopropanolamine and triisopropanolamine) and N-alkylated ethanolamines.

[0063] The deflocculating agent can also be a silicate such as sodium silicate, sodium metasilicate or sodium trisilicate.

[0064] Alternatively, the deflocculating agent may be a mixture of compounds, such as a mixture comprising at least two compounds selected from: non-ionic surfactant, anionic agent, polyacrylate, amine and organophosphorus compound.

[0065] In particular, the deflocculating agent may be a mixture of sodium silicate and sodium carbonate.

[0066] Preferably, the deflocculating agent is selected from: a lignosulfonate (e.g., sodium lignosulfonate), a polyacrylate, a humate, and mixtures thereof.

[0067] The deflocculating agent is preferably in the form of a salt.

[0068] However, the invention cannot be limited to the deflocculants mentioned above; any type of deflocculant known to a person skilled in the art can be used in place of the aforementioned deflocculants.

[0069] In particular, the deflocculating agent represents at least 0.5% by weight of the raw clay matrix, preferably at least 1% by weight of the raw clay matrix, more preferably at least 2% by weight of the raw clay matrix, even more preferably at least 3% by weight of the raw clay matrix, and for example at least 4% by weight of the raw clay matrix. Indeed, with such concentrations of deflocculating agent, the binder formulation according to the invention can then be used in combination with an activation composition to form a material with advantageous mechanical properties.

[0070] Furthermore, the deflocculating agent represents at most 20% by weight of the raw clay matrix, preferably at most 10% by weight of the raw clay matrix. Indeed, an excessively high concentration is not necessary to form a material with advantageous mechanical properties.

[0071] In particular, the deflocculating agent represents between 0.5 and 20% by weight of the raw clay matrix, preferably between 1 and 10% by weight of the raw clay matrix, more preferably between 3 and 10% by weight of the raw clay matrix and even more preferably between 4 and 10% by weight of the clay matrix flood.

[0072] According to another aspect, the invention relates to a construction binder comprising the constituents of the construction binder formulation according to the invention and an activation composition.

[0073] It is the addition of the activation composition, in conjunction with the raw clay matrix and the deflocculating agent, that will give the construction binder its mechanical properties of interest.

[0074] The construction binder can advantageously take the form of a two-component multi-component system, that is to say, comprise its constituents, namely raw clay matrix, deflocculating agent and activation composition, in a juxtaposed form.

[0075] In particular, prior to a mixing step necessary for the effective use of the construction binder, the construction binder can be prepared so that the activation composition does not come into contact with the raw clay matrix and / or the deflocculating agent. This feature has the advantage of improving the stability of the construction binder before its use.

[0076] For example, the building binder may consist of a combination of a mixture corresponding to the binder formulation according to the invention and an activation composition contained in another container. In a two-component or multi-component system, the constituents may not all be in the same form (e.g., liquid, solid, or paste), or the constituents may be in paste form, or they may be contained in different containers.

[0077] Without being limited by the theory, the activation composition will allow the formation of a network between the clay sheets which will bring its mechanical properties to the construction binder according to the invention.

[0078] The activation composition is for example present at a content of at least 10% by weight of the construction binder, preferably at least 15% by weight of the construction binder, more preferably at least 20% by weight of the construction binder, even more preferably at least 25% by weight of the construction binder, and for example at least 30% by weight of the construction binder.

[0079] In addition, the activation composition may represent at most 50% by weight of the construction binder, preferably at most 45% by weight of the construction binder, and more preferably at most 40% by weight of the construction binder.

[0080] In particular, the activation composition can represent between 10 and 50% by weight of the construction binder, preferably between 15 and 50% by weight of the construction binder, more preferably between 1 and 10% by weight of the construction binder, even more preferably between 2 and 8% by weight of the construction binder and for example between 2 and 5% by weight of the construction binder.

[0081] In particular, the activation composition may comprise metal oxides and / or be an alkaline activation composition.

[0082] Preferably, the metal oxides are transition metal oxides.

[0083] Preferably, the metal oxides are selected from: oxides iron such as FeO, Fe3O4, Fe2O3, Fe2O3, alumina A12O3, manganese(II) oxide MnO, titanium(IV) oxide TiO2 and their mixtures.

[0084] The metal oxides can preferably come from a composition of blast furnace slags, for example, formed during the production of pig iron from iron ore.

[0085] The metal oxides are present at a content of at least 2% by weight of the construction binder, preferably at least 5% by weight of the construction binder, more preferably at least 10% by weight of the construction binder.

[0086] When the activation composition is an alkaline activation composition. The alkaline composition may preferably comprise a compound having a pKa greater than or equal to 10, more preferably greater than or equal to 12, and even more preferably substantially equal to 14.

[0087] The alkaline composition may for example include an organophosphorus compound such as sodium tripolyphosphate designated by the acronym NaTPP.

[0088] In particular, the activation composition may comprise a mixture of sodium hydroxide and sodium silicate.

[0089] Advantageously, the activation composition can be an alkaline activation composition further comprising metal oxides. As will be shown in the examples, construction binders prepared from such an activation composition exhibit good mechanical properties. Thus, preferably, the activation composition can comprise metal oxides and at least one compound having a pKa greater than or equal to 10.

[0090] In addition to the raw clay matrix, the deflocculating agent and the activation composition, the construction binder may contain flashed or unflashed metakaolin, cement, lime and / or plaster.

[0091] Despite the possible presence of such additives, preferably the raw clay matrix represents at least 30% by weight of the construction binder, preferably at least 40% by weight of the construction binder, preferably between 40 and 80% by weight, even more preferably between 50 and 60% by weight.

[0092] Similarly, the deflocculating agent may represent at least 0.25% by weight of the construction binder, preferably at least 0.5% by weight of the construction binder, more preferably at least 1% by weight of the construction binder, even more preferably at least 1.5% by weight of the construction binder, and for example at least 2% by weight of the construction binder.

[0093] In addition, the deflocculating agent may represent at most 20% by weight of the construction binder, preferably at most 15% by weight of the construction binder, and more preferably at most 10% by weight of the construction binder.

[0094] In particular, the deflocculating agent may represent between 0.25 and 10% by weight of the construction binder, preferably between 0.5 and 10% by weight of the construction binder, more preferably between 1 and 10% by weight of the construction binder, even more preferably between 2 and 8% by weight of the construction binder and for example between 2 and 5% by weight of the construction binder.

[0095] In a particular embodiment, a construction binder according to the invention comprises: - 30% to 80% by weight of raw clay matrix, - 10% to 10% by weight of deflocculating agent, and - 10% to 50% by weight of an activation composition.

[0096] Preferably, a construction binder according to the invention comprises: - 50% to 75% by weight of raw clay matrix, - 1% to 10% by weight of deflocculating agent, and - 15% to 50% by weight of an activation composition.

[0097] More preferably, a construction binder according to the invention comprises: - 50% to 70% by weight of raw clay matrix, - 2% to 5% by weight of deflocculating agent, and - 15% to 45% by weight of an activation composition.

[0098] More preferably, a construction binder according to the invention comprises: - 50% to 60% by weight of raw clay matrix, - 2% to 5% by weight of deflocculating agent, and - 25% to 45% by weight of metal oxides.

[0099] Even more preferably, a construction binder according to the invention comprises: - 30% to 80% by weight of raw clay matrix, - 1% to 10% by weight of deflocculating agent, - 10% to 40% by weight of metal oxides, and - 2% to 15% by weight of a strong base.

[0100] In addition, the water mass ratio to dry matter of the composition referred to herein as construction binder is controlled and is preferably less than 1, advantageously substantially equal to 0.6.

[0101] In another aspect, the invention relates to a process for preparing a construction binder. Such a process according to the invention, illustrated in [Fig. 1], has the advantage of being a so-called low-carbon process, that is to say, one whose greenhouse gas emissions, such as in particular carbon dioxide emissions, are reduced compared to the greenhouse gas emissions of known construction binder preparation processes. Such reductions in greenhouse gas emissions are notably linked to the absence of a calcination step, which is particularly energy-intensive.

[0102] The process particularly includes the preparation 110 of a clay suspension comprising at least one raw clay matrix, a deflocculating agent, and water. As before, the raw clay matrix may comprise at least one mineral species selected from: Kaolinite, Illite, Smectite, Bentonite, Chlorite, Montmorillonite, Muscovite, Hallocyte, Sepiolite, Attapulgite, Vermiculite, and so-called interstratified clays, which are complex combinations of several clays.

[0103] During the preparation step 110 of the suspension, water can be added so that the ratio between the mass of water and the mass of construction binder is less than 1 and for example between 0.4 and 0.8. In addition, water can advantageously be added after the raw clay matrix and the deflocculating agent have been mixed dry.

[0104] Advantageously, the raw clay matrix used in the clay suspension preparation step 110 can be obtained from excavated soil near the construction site. Thus, the construction binder preparation process may include a soil excavation step containing a raw clay matrix prior to the clay suspension preparation 110. Furthermore, in this case, the process may include a preparation step for the excavated soil, such preparation potentially including, for example: drying, grinding, sieving, and storage.

[0105] Thus, the construction binder preparation according to the invention can enable the preparation of on-site concrete made at least in part from raw materials sourced from the construction site. Such characteristics further contribute to reducing the environmental footprint of the concrete produced.

[0106] Preferably, the process according to the invention may include, following the preparation of the clay suspension, a step 120 of mixing the clay suspension so as to obtain a dispersed or deflocculated clay suspension.

[0107] This mixing step 120 of the clay suspension can advantageously but not exclusively be carried out in a device selected from: a mixer and a mixer truck or more generally in any device suitable for mixing a clay suspension for the production of a construction binder.

[0108] This mixing step 120 of the clay suspension, before the addition of the activation composition, can be carried out over a period of at least 10 seconds, preferably at least 30 seconds, more preferably at least 60 seconds.

[0109] In addition, this mixing step 120 of the clay suspension, before the addition of the activation composition, can be carried out over a period of at most 24 hours, preferably at most 12 hours, more preferably at most 6 hours.

[0110] The process also includes a step 130 of adding an activation composition to the clay suspension. As detailed previously, the activation composition may include metal oxides and / or be an alkaline activation composition.

[0111] The process includes a homogenization step 140, or mixing, so as to obtain a construction binder.

[0112] Before, concurrently or after the addition of the activation composition, the process according to the invention may include the addition of additives or materials to modify the mechanical properties of the final construction material.

[0113] The added materials may, for example, be recycled or non-recycled aggregates chosen from fillers, powders, sand, gravel, pebbles, and / or fibers, and possibly pigments.

[0114] The process may also include the addition of a plasticizer. The plasticizer may, for example, be a polyacrylate, a polynaphthalene sulfonate, a polycarboxylate, or a polyphosphonate.

[0115] The process may also include the addition of fibers. The fibers are selected, for example, from: plant fibers such as cotton, flax, hemp, cellulose, bamboo, and miscanthus fibers; and synthetic fibers such as metallic, glass, carbon, and polypropylene fibers, and mixtures thereof. The presence of fibers can enable the formation of a construction material with improved mechanical and insulating properties.

[0116] The process may also include the addition of aggregates. The aggregates are selected, for example, from: gravel, crushed concrete, recycled concrete and mixtures thereof.

[0117] The process may also include the addition of an additive. The additive is, for example, selected from: a synthetic or natural rheological stabilizing agent, an anti-shrinkage agent, a water-retaining agent, an air-entraining agent, a synthetic resin, and mixtures thereof.

[0118] The preparation of a construction binder according to the invention shall include, in particular, the addition of sand and water. The sand may optionally be derived from excavated material, particularly in the case of "site" concrete. The sand may also be desert sand.

[0119] The construction materials obtained can, for example, be selected from: mortars, coatings, or plasters.

[0120] Thus, according to another aspect, the invention relates to a construction material formed from the construction binder according to the invention.

[0121] Furthermore, the invention relates to a construction binder obtained from the process according to the invention. The invention relates to a construction material obtained from the process according to the invention.

[0122] The invention allows in particular the manufacture of: - insulating building material: from a building binder according to the invention supplemented with lightweight aggregates of the "vegetable or porous" type; - Lightweight concrete: made from a construction binder according to the invention, with the addition of a foaming agent such as aluminum powder. This will trap air in the material and improve its insulating properties; - Prefabrication elements: manufacturing of concrete blocks or slabs in a factory from the construction binder according to the invention; and - Insulation modules.

[0123] Thus, the invention also relates to the use of the construction binder according to the invention, for the production of coating elements, for the production of extruded or molded construction modules, or more generally for the production of various extruded shapes.

[0124] Cladding elements can, for example, be selected from floor coverings, such as tiles, slabs, paving stones or edging; wall coverings, such as interior or exterior facade elements, facing bricks, cladding elements; or roofing materials such as tiles. Extruded or molded building modules, for example, are bricks.

[0125] The invention also relates to the use of the construction binder according to the invention, for the production of composite materials, prefabricated blocks,

[0126] Composite materials are, for example, prefabricated panel-type construction panels, while prefabricated blocks are, for example, door or window lintels, prefabricated wall elements, or any other prefabricated construction element.

[0127] The invention also relates to the use of the construction binder according to the invention for the production of insulation modules, such as partition panels or lightweight insulating construction modules. These insulation modules have, for example, a density of less than 1.5 kg / L, preferably less than 1.2 kg / L, more preferably less than 1.0 kg / L, and even more preferably less than 0.7 kg / L.

[0128] The invention also relates to the use of the construction binder according to the invention for implementing additive manufacturing. In particular, implementing additive manufacturing can be carried out using an automated 3D construction system such as a 3D printer. Such additive manufacturing can allow the manufacture of construction elements, buildings or houses, or even decorative objects.

[0129] As illustrated by the examples below, the present invention provides a solution based on a mixture of raw clay matrix, deflocculating agent, and activation composition to offer a construction binder with mechanical properties similar to the standard while exhibiting a reduced carbon footprint. EXAMPLES: Preparation of a construction binder:

[0130] In all the examples presented below, the formulations according to the invention are prepared according to an identical protocol, namely that a dry premix is ​​made between a raw clay matrix and a deflocculating agent in predetermined quantities, then water is added and the solution is mixed at low speed, i.e. approximately 600 revolutions per minute for 30 seconds. Next, an activation composition is added to the premix and then the premix is ​​mixed at high speed, i.e. approximately 1,500 revolutions per minute for 3 minutes.

[0131] The water mass ratio to dry matter of the composition (also called construction binder) is adjusted to a value substantially equal to 0.6.

[0132] The construction binder thus formed is then poured into a mold and left to mature at room temperature, i.e. about 20 degrees Celsius for twenty-eight days.

[0133] Methodology for measuring the mechanical properties of construction binders:

[0134] Once the maturation process is complete, the building binder is removed from the mold and the mechanical strength is measured. The mechanical strength of a building binder is understood to be its compressive strength, such compression being measured according to standard NF EN 196-1, for a cylinder with a diameter of 40 millimeters and a height of 80 millimeters and is expressed in Mega Pascals (MPa).

[0135] Comparison of the construction binders according to the invention with known construction binders:

[0136] Table 2 below presents, for different types of construction binders, known formulations and a formulation according to the invention. The mass of the components relating to each formulation is expressed as a percentage of the total mass of the construction binder (dry weight).

[0137] [Tables2] Formulations Binder CEM1 (Reference) HP2A1 (Reference) CMT (Reference) MUP1 Raw Clay Matrix 0.0% 0.0% 75.0% 55.0% Deflocculating Agent 0.0% 0.0% 0.0% 3.0% Activation Composition 0.0% 65.0% 10.0% 42.0% Metakaolin 0.0% 35.0% 0.0% 0.0% CEM1 Cement 100.0% 0.0% 15.0% 0.0% Compressive Strength (MPa) 45 42 25 45 Estimated Carbon Footprint High Medium Medium Low

[0138] Thus, Table 2 presents the mechanical resistances of known construction binders (CEM1 binder, HP2A1, CMT) and not part of the invention, such as the CEM1 type construction binder better known as "Portland" cement, whose compressive strength is around 45 MPa.

[0139] The HP2A1 formulation can be obtained by following the instructions in patent application FR3034094. The HP2A1 type construction binder comprises 35% by weight of Metakaolin obtained by calcination of kaolin, and 65% by weight of an activation composition. Thus, the relative mechanical strength of such a construction binder, on the order of 42 MPa, is lower than the strength of the Portland type construction binder.

[0140] Finally, the CMT construction binder, obtained following the instructions of patent application FR3016376, comprises 75% by weight of raw clay matrix, 10% by weight of an activation composition including lime, and 15% by weight of Portland cement. The mechanical strength associated with such a binder containing a majority of raw clay matrix is ​​on the order of 25 MPa and therefore exhibits a compressive strength significantly lower than that of Portland or HP2A1 type construction binders.

[0141] Table 2 also presents a formulation MUP1 according to the invention. It is important to note that this formulation, containing 3% deflocculant, although comprising a majority of raw clay matrix, exhibits mechanical strength identical to that of Portland cement. Importance of the deflocculating agent

[0142] Table 3 below presents a known formulation HP2A_X02 and a formulation according to the invention MUP2.

[0143] [Tables3] HP2A2 Formulations (Reference) MUP2 Raw Clay Matrix 54% 51% Deflocculating Agent 0% 3% Alkaline Silicate Solution 23% 16% Metakaolin 18% 20% LHF 5% 10% Compressive Strength (MPa) 27 43

[0144] The HP2A2 type construction binder comprises 54% by weight of raw clay matrix, 23% by weight of an activation composition (alkaline silicate solution), 18% by weight of metakaolin, and 5% of LHF. Such a formulation can, in particular, be derived from the teaching of patent application FR3034094. The mechanical strength associated with such a binder is on the order of 27 MPa.

[0145] On the contrary, the MUP2 binder obtained according to the invention, having a composition substantially identical except for the presence of a 3% deflocculating agent, exhibits a mechanical strength of 43 MPa. Such a strength can be considered equivalent to that of Portland cement.

[0146] Table 4 below presents the formulation according to the invention already presented MUP1 and an equivalent formulation to which the deflocculating agent has not been added.

[0147] [Tables4] Formulations MUP1 CMT2 (Reference) Raw Clay Matrix 55.0% 57.1% Deflocculating Agent 3.0% 0.0% Activation Composition 41.5% 42.9% Compressive Strength (MPa) 45 25

[0148] This comparison shows that a formulation according to the invention can achieve a mechanical strength of 45 MPa, whereas the same formulation without a deflocculant (CMT2) only exhibits a mechanical strength of 25 MPa. As described previously, the presence of a deflocculant in combination with the raw clay matrix and the activation composition improves the mechanical strength of a construction binder.

[0149] Use of a combination of metal oxides and an alkaline activation composition:

[0150] Table 5 below details the formulation of several construction binders according to the invention. These construction binders differ in particular in that some comprise an alkaline activation composition (a NaTPP solution in this case) and others Portland cement.

[0151] [Tables5] Formulations MUP1 MUP3 MUP4 MUP5 Raw Clay Matrix 55.3% 54.6% 54.0% 51.3% Deflocculating Agent 3.2% 2.7% 3.1% 2.9% LHF 38.6% 17.5% 31.9% 18.8% NaTPP 2.9% 0.0% 11.0% 0.0% CEM1 Cement 0.0% 25.2% 0.0% 27.0% Compressive Strength (MPa) 45 41 45 42

[0152] Table 5 shows that the formulations comprising a mixture: - blast furnace slag (BFS) which contains metallic oxides and - sodium tripolyphosphate

[0153] exhibit mechanical resistances at 45 MPa, identical to Portland cement.

[0154] Equivalent formulations in which the alkaline activation composition has been replaced by CEM1 cement exhibit sufficient but slightly lower mechanical strengths.

[0155] Concrete formulation from a construction binder according to the invention:

[0156] Table 6 below details the formulation of several concretes including a concrete reference concretes formed from Portland cement (B-Portland) and concretes formed from construction binder according to the invention (MUP_BA1, MUP_BA2, MUP_BA3). These concretes differ in particular in the nature of the raw clay matrix, the nature of the deflocculating agent and the activation compositions used.

[0157] [Tableauxô] B-Portla nd MUP_BA1 MUP_BA2 MUP_BA3 Cement CEM I 52.5 N kg / m3 (%m / lia nt) 240 (100%) 84 (26%) 0 0 Argile Nature / aquitaine kaolinite bentonite kg / m3 (%m / lia nt) 165 (55%) 178 (54%) Deflocculating agent Nature / sodium humides lignosulfonate sodium polyacrylate kg / m3 (%m / lia nt) 0 10 (3%) 10 (3%) 10 (3%) Activation composition Nature / LHF LHF (40%) + NaOH + Nature (27%) NaTTP (26%) kg / m3 (%m / lia nt) 0 54 (16%) 101 (31%) 141 (43%) Metakaolin kg / m3 (%m / lia nt) 0 0 54 (16%) 0 Superplasticizer Nature Time 1 2 Time 12 Time 12 kg / m 2.64 2.64 2.64 Sand 0-4 kg / m3 900 900 900 900 Granules 4-12 kg / m3 780 780 780 780 Water kg / m2 38 39 41

[0158] As shown in Table 6, the concretes according to the invention exhibit compressive strengths equivalent to those obtained with concrete made with Portland cement. Thus, the present invention makes it possible to form a low-carbon construction binder from a raw clay matrix, exhibiting sufficient mechanical properties to make it a construction material meeting the majority of the sector's needs.

Claims

Demands

1. Construction binder comprising a raw clay matrix, a deflocculating agent, an activation composition and water, said raw clay matrix representing at least 30% by weight of the construction binder, said construction binder taking the form of a multi-component system comprising on the one hand the activation composition and on the other hand the raw clay matrix, the deflocculating agent and water, the mass ratio of water to the raw clay matrix, the deflocculating agent and the activation composition is between 0.4 and 0.

8.

2. Construction binder according to claim 1, characterized in that the raw clay matrix comprises at least one mineral species selected from: Kaolinite, Illite, Smectite, Bentonite, Chlorite, Montmorillonite, Muscovite, Hallocyte, Sepiolite, Attapulgite, Vermiculite and so-called interstratified clays which are complex combinations of several clays.

3. Construction binder according to any one of claims 1 or 2, characterized in that said construction binder comprises at least 80% by weight of raw clay matrix.

4. Construction binder according to any one of claims 1 to 3, characterized in that the deflocculating agent is selected from: - a nonionic surfactant such as a polyoxyethylene ether; - an anionic agent such as an anionic agent selected from: alkylaryl sulfonates, amino alcohols, carbonates, silicates, fatty acids, humates (e.g., sodium humates), carboxylic acids, lignosulfonates (e.g.,sodium lignosulfonates), polyacrylates, phosphates or polyphosphates such as sodium hexametaphosphate, sodium tripolyphosphate, sodium orthophosphate, carboxymethylcelluloses and mixtures thereof; - a polyacrylate such as a polyacrylate selected from sodium polyacrylate or ammonium polyacrylate; - an amine such as an amine selected from: 2-amino-2-methyl-l-propanol; mono-, di- or triethanolamine; isopropanolamines (l-Amino-2-propanol, diisopropanolamine and triisopropanolamine) and N-alkylated ethanolamines; or. - their mixtures.

5. Construction binder according to any one of claims 1 to 4, characterized in that the deflocculating agent represents at least 0.5% by weight of the raw clay matrix.

6. Construction binder according to any one of claims 1 to 4, characterized in that the deflocculating agent represents at least 1% by weight of the raw clay matrix.

7. Construction binder according to any one of the preceding claims, characterized in that the activation composition is an alkaline activation composition.

8. Construction binder according to any one of the preceding claims, characterized in that the activation composition comprises metal oxides.

9. Construction binder according to claim 8, characterized in that the metal oxides are present at a content of at least 2% by weight of the composition.

10. Construction binder according to any one of claims 8 or 9, characterized in that the metal oxides are selected from: iron oxides such as FeO, Fe3O4, Fe2O3, alumina A12O3, manganese(II) oxide MnO, titanium(IV) oxide TiO2 and mixtures thereof.

11. Construction binder according to any one of the preceding claims, characterized in that the activation composition comprises cement.

12. Construction binder according to any one of the preceding claims, characterized in that it comprises: - from 50% to 89% by weight of raw clay matrix, - from 10% to 15% by weight of deflocculating agent, and - from 10% to 49% by weight of activation composition.

13. A process (100) for preparing a construction binder comprising the following steps: - Preparing (110) a clay suspension comprising at least a raw clay matrix, a deflocculating agent, and water, - Adding (130) an activation composition to the clay suspension, said activation composition being an alkaline activation composition and / or comprising metal oxides, and - Mixing (140) to obtain a construction binder, said raw clay matrix representing at least 30% by weight of the construction binder, the mass ratio between water on the raw clay matrix, the deflocculating agent and the activation composition is between 0.4 and 0.

8.

14. A preparation process according to claim 13, characterized in that it comprises a mixing step (120) of the clay suspension so as to obtain a deflocculated clay suspension and in that the activation composition is added after the mixing step (120).

15. Construction material such as mortar, plaster, gypsum, insulation, lightweight concrete, prefabricated element, comprising the construction binder according to any one of claims 1 to 10

16. 1Z. Construction material according to claim 15, characterized in that it further comprises one or more fillers, the fillers being for example chosen from mineral fillers or vegetable fillers.

17. Construction material according to any one of claims 15 or 16, characterized in that it further comprises an expansive or foaming agent, such as aluminum powder.

18. Use of the construction binder according to any one of claims 1 to 12, for the production of cladding elements, in particular floor coverings, such as tiles, slabs, paving stones or borders, wall coverings, such as interior or exterior facade elements, facing bricks, cladding elements, or roof coverings of the tile type, for the production of extruded or molded construction modules, such as bricks, or for the production of various extruded shapes.

19. Use of the construction binder according to any one of claims 1 to 12, for the production of composite materials, such as prefabricated panel-type construction panels, prefabricated blocks such as door or window lintels, prefabricated wall elements, or any other prefabricated construction element.

20. Use of the construction binder according to any one of claims 1 to 12, for the production of insulation modules, such as partition panels, or lightweight insulating construction modules (with a density of less than 1.5 kg / L, of preferably less than 1.2 kg / L, preferably even less than 1.0 kg / L, preferably even less than 0.7 kg / L)

21. Use of the construction binder according to any one of claims 1 to 12, for the production by additive manufacturing, such as by means of a 3D printer, of construction elements, buildings or houses, or decorative objects.

22. Use of the construction binder according to any one of claims 1 to 12, in the form of a two-component system with either the constituents in solid form and the constituents in liquid form, or the constituents in the form of two pastes, for the production of sealant, adhesive or sealing mortar.

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