NEW FORMULATION FOR LOW-CARBON CONSTRUCTION BINDER, PREPARATION PROCESS AND CONSTRUCTION MATERIALS

Description

[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 art]

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

[0003] 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 temperatures exceeding 1200°C, making cement production a highly energy-intensive process. 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 carbon dioxide emissions generated by the cement industry.

[0004] One initial solution led to the creation of a cement plant operating on a combination of waste-based alternative fuels and technologies related to capturing and storing carbon emitted during cement production, aiming for zero emissions. However, these solutions are not yet available on an industrial scale and require substantial investment.

[0005] 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 for their production, would reduce 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).

[0006] 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, these 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.

[0007] 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 its ability, lacking inherent binding properties, to react chemically with calcium hydroxide at room temperature in finely divided form and in the presence of moisture to form compounds with binding properties. Kaolinitic clays are widely available in the Earth's crust, and heat treatment (e.g., 600–800°C for a short period, known as "flash heating") leads to the dehydroxylation of the kaolinite crystal structure, yielding 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, notably those containing flash-cured metakaolin combined with sodium hydroxide, as described in document FR3034094 or US10315115. The rheological properties of these construction binders can be further improved by adding plasticizers or water reducers such as polyacrylates or lignosulfonates. However, such processes, requiring high temperatures, have high energy consumption and therefore a carbon footprint that needs to be reduced.

[0008] 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 liquid permeability, or required the addition of a portion of Portland cement to achieve acceptable mechanical properties.

[0009] Furthermore, it has traditionally been proposed to add building binders to earth to create construction materials. However, these building materials have limited mechanical properties. Indeed, the book "Construire en terre crue, construction - rénovation - finirs" (Building with Raw Earth: Construction - Renovation - Finishing) by Ulrich Röhlen and Christof Ziegert (2013, Éditions Le Moniteur, ISBN 978-2-281-11567-3) indicates that the compressive strength of earth concrete varies from 0.6 MPa to a maximum of 12 MPa, with a typical value of around 3 MPa. Moreover, the book "Traité de construction en terre" (Treatise on Earth Construction) measures the evolution of the compressive strength of cement-stabilized earth and shows, in particular, that the compressive strength of earth concrete containing 7% cement (i.e., 50% cement in the binder made of cement and clay) never exceeds 12 MPa.This has always discouraged builders from using excessively high levels of raw clay in construction binders and, more broadly, in building materials requiring high compressive strength. Similarly, the compressive strength of unfired clay bricks has been studied (J.E. Oti et al., "Engineering properties of unfired clay masonry bricks," Engineering Geology 2009). However, the mechanical performance of the materials studied did not exceed 8 MPa after 90 days of curing.

[0010] Thus, there is a need for new construction binder formulations with a low carbon footprint while generating concrete mechanical properties at least equivalent to or even superior to the mechanical properties of concretes made from cements commonly used in the construction field, 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, on the one hand, yields a construction material with mechanical properties at least equivalent to Portland cement, and on the other hand, improves the comfort of the inhabitants compared to concrete made from Portland cement.

[0012] The invention further aims to provide a manufacturing process for a construction binder that reduces greenhouse gas emissions, such as carbon dioxide, released during its preparation, while preserving the binder's suitable mechanical properties for use in construction. The invention also relates to the use of a construction binder for building elements that improves occupant comfort compared to conventional concrete, particularly the hygrothermal properties of buildings. [Brief description of the invention]

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

[0014] A 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 of the construction using a binder from this formulation. Depending on other optional formulation characteristics :

[0016] 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. The presence of one or more of these mineral species in the binder formulation makes it possible to obtain a cement, and more broadly a construction material, exhibiting good mechanical properties, i.e., mechanical properties equivalent to those of a construction material containing Portland cement. Preferably, the raw clay matrix comprises at least one mineral species selected from: 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 allows for the improvement of the mechanical properties of materials constructed from this formulation. 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-1-propanol; mono-, di-, or triethanolamine; isopropanolamines (1-amino-2-propanol, diisopropanolamine, and triisopropanolamine) and N-alkylated ethanolamines; or mixtures thereof. These deflocculating agents allow for 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, more preferably between 1 and 10% by weight.Such a concentration improves the mechanical properties of materials constructed from this formulation. It comprises: ∘ 80% to 99.5% by weight of raw clay matrix, and ∘ 0.5% to 20% by weight of deflocculating agent. Such a construction binder formulation, when used in conjunction with an activation composition, provides mechanical properties equivalent to Portland cement.

[0017] The invention further discloses on a building binder comprising the constituents of the construction binder formulation according to the invention and an activation composition.

[0018] In particular, the invention relates to a construction binder comprising a raw clay matrix, a deflocculating agent and an activation composition, characterized in that it comprises at least 30% by weight of raw clay matrix and at least 2% by weight of metal oxides, and in that the activation composition is an alkaline activation composition comprising at least one compound having a pKa greater than or equal to 10.

[0019] The activation composition allows the construction binder to acquire its desired mechanical properties and in particular to structure the clay sheets. Depending on other optional characteristics of the construction binder:

[0020] The construction binder contains less than 30% by weight of metakaolin, preferably less than 26% by weight, more preferably less than 21% by weight, less than 17% by weight, less than 13% by weight, and even more preferably less than 10% by weight, or less than 5% by weight. For example, it may contain no metakaolin at all. 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.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. It comprises at least 40% by weight of raw clay matrix. The deflocculating agent is selected from: a non-ionic 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 humates).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-1-propanol; mono-, di-, or triethanolamine; isopropanolamines (1-amino-2-propanol, diisopropanolamine, and triisopropanolamine) and N-alkylated ethanolamines; or mixtures thereof. The deflocculating agent represents at least 0.25% by weight of the building binder. The activation composition represents at least 10% by weight of the building binder. The raw clay matrix, the deflocculating agent and the activation composition form a two-component or multi-component system.It comprises: 30% to 80% by weight of raw clay matrix, 0.25% to 20% by weight of deflocculating agent, and 10% to 50% by weight of an activation composition. The alkaline composition may, for example, include a compound with a pKa greater than or equal to 12, and more preferably approximately 14. The activation composition includes an organophosphate compound such as sodium tripolyphosphate; preferably, the organophosphate compound represents at least 2% by weight of the construction binder. In particular, the activation composition includes metal oxides. Specifically, the metal oxides are present at a content of at least 2% by weight of the composition, preferably at least 5% by weight of the composition, and more preferably at least 10% by weight of the composition. 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, alumina Al2O3, manganese(II) oxide MnO, titanium(IV) oxide TiO2, and mixtures thereof. The activation composition includes cement, preferably Portland cement. The cement may, for example, be a CEM I type cement. It includes a blast furnace slag composition, preferably representing at least 5% by weight of the construction binder. It comprises: 40% to 70% by weight of raw clay matrix, 0.5% to 6% by weight of deflocculating agent, 5% to 20% by weight of an activation composition, and 20% to 45% by weight of blast furnace slag. It comprises: 35% to 65% by weight of raw clay matrix, 0.5% to 5% by weight of deflocculating agent, 31% to 49% by weight of Portland CEM1 cement.It comprises: 35% to 65% by weight of raw clay matrix, 0.5% to 5% by weight of deflocculating agent, 10% to 30% by weight of blast furnace slag, and 15% to 35% by weight of Portland CEM1 cement. It comprises: 45% to 70% by weight of raw clay matrix, 0.5% to 6% by weight of deflocculating agent, 10% to 35% by weight of an activation composition, and 15% to 30% by weight of metakaolin. It comprises: 45% to 70% by weight of raw clay matrix, 0.5% to 5% by weight of deflocculating agent, 10% to 25% by weight of an activation composition, 5% to 20% by weight of blast furnace slag, and 15% to 30% by weight of metakaolin.

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

[0022] The invention also relates to a process for preparing a construction binder.

[0023] The process for preparing a construction binder may include a step of mixing a raw clay matrix, a deflocculating agent and an activation composition, said construction binder comprising at least 30% by weight of raw clay matrix.

[0024] In particular, the process of preparing a construction binder may include the following steps: Prepare a clay suspension comprising at least one raw clay matrix, a deflocculating agent and water, Add an activation composition to the clay suspension, said activation composition being an alkaline activation composition comprising at least one compound having a pKa greater than or equal to 10, and Mix so as to obtain a construction binder, preferably said construction binder comprising at least 30% by weight of raw clay matrix and at least 2% by weight of metal oxides. Depending on other optional characteristics of the process:

[0025] It includes a step of mixing the clay suspension 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. It may also comprise at least 40% by weight of raw clay matrix, preferably between 40 and 60% by weight. The deflocculating agent represents at least 0.25% by weight of the construction binder, preferably at least 0.5% by weight, and more preferably between 0.5% and 10% by weight. The activation composition is present at a content of at least 10% by weight of the binder. For example, metal oxides are present at a content of at least 10% by weight of the binder.

[0026] The invention further discloses on 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. Depending on other optional characteristics of the building material:

[0027] The construction binder comprises excavated earth, said excavated earth including the raw clay matrix. Indeed, unlike known construction materials, it is possible within the scope of the invention to produce a construction binder, and therefore by extension a construction material, directly from excavated earth and exhibiting satisfactory compressive strength. The excavated earth may further comprise aggregates, such as, by way of non-limiting example, sand and / or gravel. It further comprises 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, and / or fibers.The fibers may be, in particular, 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, pigments, and an expanding 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 construction panels of the prefabricated panel type, prefabricated blocks such as door or window lintels, prefabricated wall elements, or any other prefabricated construction 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 the constituents in solid form on the one hand, and the constituents in liquid form on the other hand, or the constituents in the form of two pastes, for the production of sealant, glue or sealing mortar.

[0033] The invention further relates to the use, for the preparation of a construction binder, of a deflocculating agent in combination with a raw clay matrix, said raw clay matrix representing at least 30% by weight of the construction binder, and an activation composition enabling the production of concrete with a minimum compressive strength on cylinders at 28 days as measured by standard NF EN 206-1 greater than or equal to 20MPa, preferably greater than or equal to 25MPa, preferably greater than or equal to 40MPa.

[0034] 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 attached Figure: The figure 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 building material should be understood as a proportion relative to the dry weight of the formulation, binder, or building material. Dry weight refers to the weight before the addition of water, for example, necessary for the formation of a building binder.

[0036] The term "Dehydrated" in the context of this 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" refers to one or more rock materials based on hydrated silicates or aluminosilicates with a lamellar structure. This clay matrix is ​​composed of fine particles generally resulting from the alteration of three-dimensional silicates, such as feldspars. A clay matrix may thus comprise a mixture of such rock materials, which could, for example, consist of kaolinite, illite, smectite, bentonite, chlorite, 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 subjected to a temperature rise exceeding 300°C, preferably exceeding 200°C, and even more preferably exceeding 150°C. Indeed, the raw clay matrix may undergo a heating stage requiring a temperature rise generally of approximately 150°C or less, but no calcination stage.

[0038] A "flocculant" or "deflocculating agent" is any compound that, in aqueous suspension, will dissociate aggregates and colloids. Flocculants have been used, for example, in drilling or oil extraction to make clay more fluid and facilitate extraction or drilling.

[0039] An "activation composition" is defined as any composition whose function is to accelerate the formation of a compact structure, thereby increasing the mechanical strength of materials incorporating such an activation composition.

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

[0041] The inventor has developed a new formulation for a construction binder which could be advantageously, but not limited to, 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, widely 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 greenhouse gas emissions, 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, reduces 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 concretes formulated with Portland cement or "low carbon" materials, such as those described above.

[0045] So, according to one 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 true 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 can be recovered and is not intended 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 raw clay matrix to be used to obtain a formulation containing 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 extemporaneouslyor 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 ranging from 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, include 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. [Table 1] Type of clay Composition Raw Clay Matrix Illite (K,H 3 O)(Al,Mg,Fe) 2 (Si,Al) 4 O 10 [(OH) 2 ,(H 2 O)] Smectite / Montmorillonite (Na,Ca) 0.3 (Al,Mg) 2 Si 4 O 10 (OH) 2, n H 2 O Kaolinite Al₂Si₂O₅(OH)₄ Metakaolin Al₂Si₂O₅(OH)₄ anhydrous Bentonite (Na,Ca) 0.3 (Al,Mg) 2 Si 4 O 10 (OH) 2

[0054] 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 construction materials, thus enabling the production of construction materials with suitable mechanical performance.

[0055] 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.

[0056] Thus, in particular, a formulation according to the invention may 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

[0057] Many compounds can act as deflocculating agents and many are generally known to those skilled in the art.

[0058] 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.

[0059] 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.

[0060] The deflocculating agent can also be a polyacrylate. It can then be selected, for example, from sodium polyacrylate and ammonium polyacrylate.

[0061] The deflocculating agent can also be a selected amine, for example, from among: 2-amino-2-methyl-1-propanol; mono-, di-, or triethanolamine; isopropanolamines (1-amino-2-propanol, diisopropanolamine, and triisopropanolamine); and N-alkylated ethanolamines. The deflocculating agent can also be a silicate, such as sodium silicate, sodium metasilicate, or sodium trisilicate.

[0062] Alternatively, the deflocculating agent may be a mixture of compounds, such as a mixture comprising at least two compounds selected from: nonionic surfactant, anionic agent, polyacrylate, amine and organophosphorus compound.

[0063] In particular, the deflocculating agent can be a mixture of sodium silicate and sodium carbonate.

[0064] Preferably, the deflocculating agent is selected from: a lignosulfonate (e.g., sodium lignosulfonate), a polyacrylate, a humate, and mixtures thereof.

[0065] The deflocculating agent is preferably in the form of a salt.

[0066] 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.

[0067] In particular, the deflocculating agent constitutes 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.

[0068] 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.

[0069] 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 raw clay matrix.

[0070] In another aspect, the invention relates to a building binder comprising the constituents of the construction binder formulation according to the invention and an activation composition.

[0071] 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.

[0072] The construction binder can advantageously take the form of a two-component multi-component system, that is to say, include its constituents, namely raw clay matrix, deflocculating agent and activation composition, in a juxtaposed form.

[0073] In particular, prior to the mixing step required for the effective use of the construction binder, the construction binder can be prepared in such a way that the activation composition does not come into contact with the raw clay matrix and / or the deflocculating agent. This characteristic has the advantage of improving the stability of the construction binder before its use.

[0074] For example, the construction binder may consist of a mixture corresponding to the binder formulation according to the invention and an activation composition contained in a separate 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 they may be in paste form, or they may be contained in different containers. The construction binder may be mixed with water, or more generally an aqueous solution, just before use, to ensure thorough mixing of the constituents. However, prior to this addition of water, it may be in a form that is at least partially dehydrated.

[0075] As will be described below, the activation composition can be a liquid composition. Thus, the building binder can be formed without the addition of water or an additional aqueous solution.

[0076] Advantageously, and as will be detailed, part of the components of the construction binder (flocculating agent and clay matrix) can be mixed with water before the addition of the activation composition.

[0077] However, construction binder can also be advantageously prepared in dehydrated form. In this case, it can, for example, be mixed with an aqueous solution just before use. This makes it easier to transport and package.

[0078] Without being limited by 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] Preferably, the activation composition represents between 10 and 35% by weight of the construction binder, even more preferably between 15 and 30% by weight of the construction binder.

[0083] The activation composition is an alkaline activation composition. It may also contain metal oxides.

[0084] Preferably, metal oxides are oxides of transition metals.

[0085] Preferably, the metal oxides are selected from: iron oxides such as FeO, Fe3O4, Fe2O3, alumina Al2O3, manganese(II) oxide MnO, titanium(IV) oxide TiO2 and mixtures thereof.

[0086] Metallic oxides can preferably originate from a composition of blast furnace slags, for example, formed during the production of pig iron from iron ore.

[0087] 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.

[0088] The alkaline composition includes a compound having a pKa greater than or equal to 10, more preferably greater than or equal to 12, even more preferably substantially equal to 14. It can then be considered as a strong base.

[0089] In particular, the activation composition may comprise a mixture of sodium hydroxide and sodium silicate. The activation composition may be used in solid form. It may also be used, for example in the case of an alkaline activation composition, in liquid form. In this case, the percentage indicated for the formulations corresponds to the weight of the liquid composition. The liquid alkaline activation composition may comprise between 10 and 70% of a mixture of sodium hydroxide and sodium silicate, preferably between 20 and 60%, and more preferably between 30 and 50%, by weight of dry product relative to the total weight of the composition.

[0090] The alkaline composition, and more broadly the activation composition, may for example include an organophosphorus compound such as sodium tripolyphosphate designated by the acronym NaTPP.

[0091] 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.

[0092] The activation composition can be aqueous. Thus, it preferably contains water. As will be described later, its use can be combined with the addition of water during the formation of a construction binder according to the present invention. Alternatively, however, the activation composition may be in solid form, for example, as a powder.

[0093] Preferably, the raw clay matrixrepresents 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 45 and 65% by weight, even more preferably between 50 and 60% by weight.

[0094] Likewise, 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.

[0095] 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.

[0096] 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, between 1 and 8% by weight of the construction binder, between 2 and 8% by weight of the construction binder, or between 2 and 5% by weight of the construction binder. Even more preferably, the deflocculating agent may represent between 0.5 and 6% by weight of the construction binder, or between 1 and 4% by weight of the construction binder.

[0097] In a particular embodiment, a construction binder according to the invention comprises: 30% to 80% by weight of raw clay matrix, 0.25% to 20% by weight of deflocculating agent, and 10% to 50% by weight of an activation composition.

[0098] Preferably, a construction binder according to the invention comprises: 45% to 60% by weight of raw clay matrix, 0.25% to 5% by weight of deflocculating agent, preferably 1% to 4%, and 10% to 50% by weight of an activation composition

[0099] 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, and 10% to 50% by weight of an activation composition.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] In addition to the raw clay matrix, the deflocculating agent, and the activation composition, the construction binder may contain flashed or unflamed metakaolin, cement, lime, and / or plaster. Furthermore, as will be illustrated in the examples, certain construction binder compositions may exhibit mechanical performance equivalent to or superior to Portland cement. Thus, even more preferably, a construction binder according to the invention comprises: 45% to 70% by weight of raw clay matrix, 0.5% to 6% by weight of deflocculating agent, 10% to 35% by weight of an activation composition, and 15% to 30% by weight of metakaolin.

[0105] Even more preferably, a construction binder according to the invention comprises: 35% to 65% by weight of raw clay matrix, 0.5% to 5% by weight of deflocculating agent, 10% to 30% by weight of blast furnace slag, and 15% to 35% by weight of Portland CEM1 cement.

[0106] Even more preferably, a construction binder according to the invention comprises: 40% to 70% by weight of raw clay matrix, 0.5% to 6% by weight of deflocculating agent, 5% to 20% by weight of an activation composition, and 20% to 45% by weight of blast furnace slag.

[0107] Even more preferably, a construction binder according to the invention comprises: 45% to 70% by weight of raw clay matrix, 0.5% to 5% by weight of deflocculating agent, 10% to 25% by weight of an activation composition, 5% to 20% by weight of blast furnace slag, and 15% to 30% by weight of metakaolin.

[0108] As mentioned, the above formulations are open formulations and the construction binder may also contain additional compounds such as plasticizers or water reducers.

[0109] In addition, the water-to-dry-matter mass ratio of the composition referred to herein as construction binder is controlled and is preferably less than 1, advantageously substantially equal to 0.6.

[0110] According to another aspect The invention relates to a preparation process of a construction binder. Such a process according to the invention, illustrated in the figure 1This process has the advantage of being considered low-carbon, meaning that its greenhouse gas emissions, particularly carbon dioxide emissions, are reduced compared to those of known construction binder preparation processes. These reductions in greenhouse gas emissions are primarily due to the absence of a calcination step, which is particularly energy-intensive.

[0111] The process specifically 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 include 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. Advantageously, the preparation step 110 is initiated from a dehydrated premix comprising a raw clay matrix and a deflocculating agent.

[0112] 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.

[0113] Advantageously, the raw clay matrix used in step 110 of the clay suspension preparation can be obtained from excavated soil near the construction site. Thus, the construction binder preparation process may include a step of excavating soil containing a raw clay matrix prior to the preparation of a clay suspension. Furthermore, in this case, the process may include a step of preparing the excavated soil, such preparation potentially involving drying, grinding, sieving, and storage.

[0114] Thus, the construction binder preparation according to the invention can enable the production of on-site concrete made at least partially from raw materials sourced from the construction site. Such characteristics further contribute to reducing the environmental footprint of the concrete produced.

[0115] 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.

[0116] 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, a dispersion device using ultrasound can also be used.

[0117] 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.

[0118] 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.

[0119] The process also includes a step 130 of adding an activation composition to the clay suspension. As detailed previously, the activation composition is an alkaline activation composition. It may also contain metal oxides.

[0120] The process includes a step 140 of homogenization, or mixing, in order to obtain a construction binder.

[0121] 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.

[0122] 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.

[0123] The process may also involve the addition of a plasticizer. The plasticizer may, for example, be a polyacrylate, a polynaphthalene sulfonate, a polycarboxylate, or a polyphosphonate.

[0124] The process may also involve the addition of fibers. These fibers are selected from a variety of sources, including plant fibers such as cotton, flax, hemp, cellulose, bamboo, and miscanthus, as well as synthetic fibers such as metallic, glass, carbon, and polypropylene fibers, and blends thereof. The presence of fibers can result in a building material with improved mechanical and insulating properties.

[0125] The process may also involve the addition of aggregates. Aggregates are selected, for example, from: gravel, crushed concrete, recycled concrete, and mixtures thereof.

[0126] The process may also involve the addition of an additive. The additive is selected, for example, 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.

[0127] The preparation of a construction binder according to the invention will notably involve the addition of sand and water. The sand may optionally come from excavated material, particularly in the case of "on-site" concrete. The sand may also be desert sand.

[0128] The building materials obtained can, for example, be selected from: mortars, coatings, or plasters.

[0129] So, according to another aspect , the invention discloses on a building material formed from the construction binder according to the invention.

[0130] Furthermore, the invention relates to a construction binder obtained by the process according to the invention. The invention also relates to a construction material obtained by the process according to the invention.

[0131] The invention allows, in particular, the manufacture of: Insulating building material: made from a construction binder according to the invention, supplemented with lightweight aggregates of a "vegetable or porous" type; lightweight concrete: made from a construction binder according to the invention, supplemented with a foaming agent such as aluminum powder. This will trap air within the material and improve its insulating properties; prefabricated elements: manufacturing of concrete blocks or slabs in a factory from the construction binder according to the invention; and insulation modules.

[0132] 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.

[0133] Cladding elements can be selected from a range of options, including floor coverings such as tiles, slabs, paving stones, or edging; wall coverings such as interior or exterior facade elements, facing bricks, or siding; and roofing materials such as tiles. Extruded or molded building modules, for example, include bricks.

[0134] The invention also relates to the use of the construction binder according to the invention, for the production of composite materials, prefabricated blocks. The composite materials are for example construction panels of the prefabricated panel type, while the prefabricated blocks are for example door or window lintels, prefabricated wall elements, or any other prefabricated construction element.

[0135] 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 building 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.

[0136] The invention also relates to the use of the construction binder according to the invention for implementing additive manufacturing. In particular, additive manufacturing can be carried out using an automated 3D printing system such as a 3D printer. Such additive manufacturing can enable the production of building components, buildings or houses, or even decorative objects.

[0137] More generally, the invention also relates to the use, for the preparation of a construction binder, of a deflocculating agent in combination with a raw clay matrix, said raw clay matrix representing at least 30% by weight of the construction binder, and an activation composition enabling the production of concrete with a minimum compressive strength at 28 days as measured by ISO 1920-4:2005 (Testing of concrete - Part 4: Strength of hardened concrete) greater than or equal to 20MPa, preferably greater than or equal to 25MPa, preferably greater than or equal to 40MPa.

[0138] The invention also relates to the use, for the preparation of a construction binder, of a deflocculating agent in combination with a raw clay matrix, said raw clay matrix representing at least 30% by weight of the construction binder, and an activation composition enabling the production of concrete with a minimum compressive strength at 28 days as measured by standard NF EN 197-1 greater than or equal to 20MPa, preferably greater than or equal to 25MPa, preferably greater than or equal to 40MPa.

[0139] 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:

[0140] 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.

[0141] The water-to-dry-matter mass ratio of the composition (also called construction binder) is adjusted to a value approximately equal to 0.6.

[0142] 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. Methodology for measuring the mechanical properties of construction binders:

[0143] Once the curing process is complete, the mechanical resistance is measured. The mechanical resistance of a construction binder is its resistance to compression, such compression being measured according to the standard NF EN 196-1, for a prism of 40 millimeters on each side and 160 millimeters in length and is expressed in Mega Pascals (MPa). Comparison of the construction binders according to the invention with known construction binders:

[0144] 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). [Table 2] Formulations CEM1 binder (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 <10 45 Estimated Carbon Footprint Forte Average Average Weak

[0145] Thus, Table 2 presents the mechanical strengths of known construction binders ( CEM1, HP2A1, CMT binder ) 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.

[0146] 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 calcining 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 a Portland-type construction binder.

[0147] Finally, the CMT construction binder, obtained following the instructions in 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 ​​approximately 25 MPa according to patent application FR3016376, and would therefore exhibit a compressive strength significantly lower than that of Portland or HP2A1 construction binders. However, a reproduction of these tests by the applicant did not achieve a strength equal to or greater than 10 MPa. Thus, in the presence of a high concentration of raw clay matrix and in the absence of a deflocculating agent, a construction binder will not produce concrete with adequate mechanical properties.

[0148] 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 (55%), exhibits a mechanical resistance identical to that of Portland cement. Importance of the deflocculating agent

[0149] Table 3 below presents a known formulation HP2A_X02 and three formulations according to the invention MUP2, MUP S9-1 and MUP S10-1. [Table 3] Formulations HP2A2 (Reference) MUP2 MUPS9-1 MUPS10-1 Raw Clay Matrix 54% 51% 51% 60% Deflocculating Agent 0% 3% 1,5% 1,0% Activation composition 23% 16% 21% 19% Metakaolin 18% 20% 19,5% 20% LHF 5% 10% 7% 0% Compressive Strength (MPa) 27 43 46 40

[0150] The HP2A2 type construction binder comprises 54% by weight of raw clay matrix, 23% by weight of an activation composition (alkaline silicate solution and / or NaTPP), 18% by weight of metakaolin, and 5% LHF. Such a formulation can, in particular, be derived from the teachings of patent application FR3034094. The mechanical strength associated with such a binder is on the order of 27 MPa.

[0151] Conversely, the MUP2 binder obtained according to the invention, which has a similar composition except for the presence of a 3% deflocculant, exhibits a mechanical strength of 43 MPa. Such a strength can be considered equivalent to that of Portland cement.

[0152] Similarly, the MUPS9-1 binder obtained according to the invention, which has a similar composition except for the presence of a 1.5% deflocculant, exhibits a mechanical strength of 46 MPa. Such strength can be considered equivalent to that of Portland cement.

[0153] These results confirm the relevance of a construction binder according to the invention and highlight the advantage conferred on compressive strength by the presence of metallic oxides, for example, from blast furnace slags.

[0154] Table 4A below presents the formulation according to the invention already presented MUP1 and an equivalent formulation to which the deflocculant agent has not been added. [Tableau 4A] Formulations MUP1 CMT2 (Reference) Raw Clay Matrix 55,0% 57,1% Deflocculating Agent 3,0% 0,0% Activation composition 42% 42,9% Compressive Strength (MPa) 45 <10

[0155] 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, according to patent application FR3016376. Furthermore, as previously stated, a reproduction of these tests by the applicant did not achieve a strength equal to or greater than 10 MPa for the CMT2 test. Thus, in the presence of a high concentration of raw clay matrix, and in the absence of a deflocculant, a construction binder will not produce concrete with adequate mechanical properties. 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.

[0156] Table 4B below presents the formulations according to the invention MUPS8-1 and MUPS12-1 in comparison with reference formulations in which the deflocculating agent has not been added. [Tableau 4B] Formulations MUPS8-1 MUPS8-2 (Reference) MUPS12-1 MUPS11-3 (Reference Raw Clay Matrix 53,0% 51% 51% 51% Deflocculating Agent 1,5% 0,0% 1% 0% Activation composition 20,5% 24% 24% 24% Metakaolin 25% 25% 24% 25% CEM1 Cement 0% 0% 0% 0% Compressive Strength (MPa) 41 27 40 29

[0157] This comparison shows that a formulation according to the invention can achieve a mechanical strength greater than or equal to 40 MPa, whereas the same formulation without a deflocculant (MUPS8-2 or MUPS11-3) does not achieve a mechanical strength of 30 MPa. As described in the preceding paragraphs, the presence of a deflocculant in combination with the raw clay matrix, the activation composition, and possibly metakaolin allows to improve the mechanical resistance of a construction binder here by more than 30%.

[0158] Table 4C below details the formulation of several construction binders according to the invention in comparison with reference binders (MUPS2-1 and MUPS2-2). These construction binders differ in particular in that the construction binders according to the invention comprise a deflocculating agent. [Tableau 4C] Formulations MUPS2-1 (ref.) MUPS2-2 (ref.) MUPS3-1 MUPS4-1 MUPS5-1 Raw Clay Matrix 50,0% 70,0% 51,0% 52,0% 53,0% Deflocculating Agent 0,0% 0,0% 2,0% 1,5% 3,0% CEM1 Cement 50,0% 30,0% 47,0% 46,5% 44,0% Compressive Strength (MPa) 8 3 25 30 33

[0159] Table 4C shows the formulations in which cement plays the role of activation composition.

[0160] Equivalent formulations in which the deflocculating agent has been removed exhibit weak and inadequate mechanical strengths.

[0161] Conversely, a combination of raw clay with a content of 50% or more, combined with cement and a deflocculating agent, achieves strengths exceeding 20 MPa. This represents a more than threefold increase in the mechanical properties obtained. Use of a combination of metal oxides and an alkaline activation composition:

[0162] 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 solution with NaTPP in this case) and others Portland cement. [Table 5] Formulations MUP3 MUP4 MUP5 MUPS2-3 MUPS5-1 Raw Clay Matrix 54,6% 54,0% 51,3% 55,0% 60,0% Deflocculating Agent 2,7% 3,1% 2,9% 1,0% 3,5% LHF 17,5% 31,9% 18,8% 0,0% 0,0% Activation composition (NaTPP + NaOH + Na2SiO3) 0,0% 11,0% 0,0% 0,0% 0,0% CEM1 Cement 25,2% 0,0% 27,0% 44,0% 36,5% Compressive Strength (MPa) 41 45 42 18 21

[0163] Table 5 shows that the formulations containing a mixture: blast furnace slag (BFS) which contains metal oxides and sodium tripolyphosphate exhibit mechanical resistances of 45 MPa.

[0164] Equivalent formulations in which the alkaline activation composition has been replaced by CEM1 cement exhibit similar mechanical strengths.

[0165] Furthermore, the MUPS5-1 composition, which does not contain LHF, exhibits acceptable but lower compressive strength values. This composition demonstrates that, thanks to the present invention, it is possible to achieve mechanical strength values ​​exceeding 20 MPa for these construction binders containing more than 50% raw clay matrix. Concrete formulation based on a construction binder according to the invention :

[0166] Table 6 below details the formulation of several concretes, including a reference concrete made from Portland cement (B-Portland) and concretes made from the 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. [Table 6] B-Portland MUP_BA1 MUP_BA2 MUP_BA3 CEM I 52.5 N Cement g (%m / binder) 240 (100%) 84 (26%) 0 0 Clay Nature / aquitaine kaolinite bentonite g (%m / binder) 0 181 (55%) 165 (50%) 178 (54%) deflocculant agent Nature / sodium humates sodium lignosulfonate sodium polyacrylate g (%m / binder) 0 10 (3%) 10 (3%) 10 (3%) Activation composition Nature / LHF LHF + NaOH + Na₂SiO₃ LHF + NaTPP + NaOH + Na2SiO3 g (%m / binder) 0 54 (16%) 101 (31%) 141 (43%) Metakaolin g (%m / binder) 0 0 54 (16%) 0 Superplasticizer Nature Tempo12 Tempo12 Tempo12 Tempo12 g 1,9 2,64 2,64 2,64 Sand 0-4 g 900 900 900 900 4-12 Aggregates g 780 780 780 780 Water g 205 185 175 175 Compressive Strength (MPa) at 28 days 40 38 39 41

[0167] As shown in Table 6, the concretes according to the invention exhibit compressive strengths equivalent to those obtained with concrete made using 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

1. A construction binder including a raw clay matrix, a deflocculating agent and an activator composition, characterized in that it comprises at least 30 wt% of a raw clay matrix and at least 2 wt% of metal oxides and wherein the activator composition is an alkaline activator composition comprising a compound having a pKa greater than or equal to 10.

2. The construction binder according to claim 1, characterized in that the deflocculating agent is selected from: - a non-ionic surfactant such as a polyoxyethylene ether; - an anionic agent such as an anionic agent selected from: alkyl aryl sulphonates, amino alcohols, carbonates, silicates, fatty acids, humates (e.g. sodium humates), carboxylic acids, lignosulphonates (e.g. sodium lignosulphonates), polyacrylates, phosphates or polyphosphates such as sodium hexametaphosphate silicates, 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-1-propanol; mono-, di- or triethanolamine; isopropanolamines (1-amino-2-propanol, diisopropanolamine and triisopropanolamine) and N-alkylated ethanolamines; or - mixtures thereof.

3. The construction binder according to claim 1 or 2, characterized in that the deflocculating agent accounts for at least 0.25 wt% of the construction binder.

4. The construction binder according to any one of claims 1 to 3, characterized in that the raw clay matrix, the deflocculating agent and the activator composition form a two-component or multi-component system.

5. The construction binder according to any one of the preceding claims, characterized in that it comprises: - 30 to 80 wt% of a raw clay matrix, - 0.25 to 20wt% of a deflocculating agent, and - 10 to 50 wt% of an activator composition.

6. The construction binder according to any one of claims 1 to 5, characterized in that the activator composition includes an organophosphorus compound such as sodium tripolyphosphate, preferably the organophosphorus compound accounts for at least 2 wt% of the construction binder.

7. The construction binder according to any one of claims 1 to 6, characterized in that the metal oxides are selected from: iron oxides such as FeO, Fe3O4, Fe2O3, alumina Al2O3, manganese (II) oxide MnO, titanium (IV) oxide TiO2 and mixtures thereof.

8. The construction binder according to any one of the preceding claims, characterized in that it includes a blast furnace slag composition, preferably the blast furnace slag composition accounts for at least 5 wt% of the construction binder.

9. The construction binder according to any one of the preceding claims, characterized in that the activator composition includes Portland cement.

10. The construction binder according to any one of the preceding claims, characterized in that the activator composition includes metakaolin.

11. The construction binder according to any one of claims 1 to 10, characterized in that it comprises: - 40 to 70 wt% of a raw clay matrix, - 0.5 to 6 wt% of a deflocculating agent, - 5 to 20 wt% of an activator composition, and - 20 to 45 wt% of blast furnace slags.

12. A method (100) of preparing a construction binder comprising the following steps: - Preparing (110) a clay suspension including at least one raw clay matrix, one deflocculating agent and water, - Adding (130) an activator composition to the clay suspension, where said activator composition is an alkaline activator composition comprising a compound having a pKa greater than or equal to 10, and - Mixing (140) so as to obtain a construction binder, where said construction binder includes at least 30 wt% of a raw clay matrix and at least 2 wt% of metal oxides.

13. The method of preparing a construction binder according to claim 12, characterized in that it includes a step of mixing (120) the clay suspension so as to obtain a deflocculated clay suspension and in that the activator composition is added after the mixing step (120).

14. The preparation method according to any one of claims 12 or 13, characterized in that the deflocculating agent accounts for at least 0.25 wt% of the construction binder, preferably at least 0.5 wt% of the construction binder, more preferably between 0.5 and 10 wt% of the construction binder.

15. The preparation method according to any one of claims 12 to 14, characterized in that it comprises the addition of aggregates, recycled or not, selected from fillers, powders, sand, grit, gravel, and / or fibers, and optionally pigments.

16. A use of a construction binder according to any one of claims 1 to 11, for the production of covering elements, in particular floor coverings, such as tiles, slabs, paving stones or edging, wall coverings, such as interior or exterior facade elements, cladding panels, boarding 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.

17. A use of a construction binder according to any one of claims 1 to 11, for the production of composite materials, such as construction panels of the prefabricated panel type, prefabricated blocks such as door or window lintels, prefabricated wall elements, or any other prefabricated construction element.

18. A use of a construction binder according to any one of claims 1 to11, for the production of insulating 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, more preferably less than 1.0 kg / L, more preferably less than 0.7 kg / L).

19. A use of a construction binder according to any one of claims 1 to 11, for the production by additive manufacturing, such as by means of a 3D printer, of construction elements, buildings or houses, or decorative objects.

20. A use, for the preparation of a construction binder, of a deflocculating agent in combination with a raw clay matrix, where said raw clay matrix accounts for at least 30 wt% of the construction binder, and an alkaline activator composition comprising a compound having a pKa greater than or equal to 10, said construction binder comprising at least 2 wt% of metal oxides, for obtaining a concrete having a minimum compressive strength on cylinders at day 28 as measured by the NF EN 206-1 standard greater than or equal to 20 MPa, preferably greater than or equal to 25 MPa, more preferably greater than or equal to 40 MPa.