OA21861A - Low-carbon binder and building materials providing summer comfort. - Google Patents

Abstract

The invention relates to a method (100) for producing a prefabrication element and to a construction binder comprising a raw clay matrix, a deflocculation agent and an activating composition, in which: - the raw clay matrix comprises at least one raw clay from the smectite family; - the at least one raw clay from the smectite family represents at least 20% by weight of the construction binder; and - the construction binder comprises less than 15% by weight of Portland cement.

Description

* BINDER AND LOW-CARBON BUILDING MATERIALS PROVIDING SUMMER COMFORT

The invention relates to the field of construction materials, and more particularly to that of binders that can be used in construction. The invention relates to a formulation for a construction binder. The invention also relates to a method for preparing a construction binder, the construction binder as such and the use of such a binder in the production of construction materials. The construction materials thus obtained, also the subject of the invention, provide summer comfort (e.g. passive regulation of hygrothermal energy) to the buildings that incorporate them.

[Prior Art]

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

Cement is a generally hydraulic binder that, when mixed with water, hardens and sets. After hardening, cement retains its strength and stability even when exposed to water. There is a wide variety of cements used throughout the world. However, all conventional cements contain clinker at a percentage ranging from 5% for some blast furnace cements to a minimum of 95% for Portland cement, which is the most widely used cement in the world today.

20* Clinker is produced by firing a mixture of approximately 80% limestone and 20% aluminosilicates (such as clays). This firing, known as clinkerization, is typically carried out at temperatures above 1200°C, making cement preparation a highly energy-intensive process. Furthermore, the chemical conversion of limestone into lime also releases carbon dioxide. As a result, 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.

In order to reduce carbon dioxide emissions associated with the construction industry, new formulations for low-carbon construction binder 30 have been proposed comprising a raw clay matrix and a deflocculation agent (WO2020141285).

However, this document mainly describes the use of compositions making it possible to reduce carbon dioxide emissions for construction materials while exhibiting high mechanical strengths. A method for selecting the composition of a construction material comprising an excavated clayey soil 35 has also been proposed (WO2020178538) or a binder comprising at least one raw clay making it possible to achieve the required performance in terms of traction adhesion for tile adhesives (FR3084357).

In addition to reducing carbon dioxide emissions, consumers could benefit from Portland cement substitutes with hygrothermal properties that can provide comfort to residents during hot periods.

The widespread use of air conditioning, heating, air recyclers 5 or ventilation systems in buildings to control temperature or humidity also generates significant CO ₂ emissions (both during their manufacture and throughout their use). On the contrary, passive control of temperature or humidity does not consume any energy by definition and does not require any human supervision. It therefore represents a more resilient and sustainable option in many situations where the energy consumption of thermal, hygrometric or more generally ventilation control systems can be reduced.

However, this aspect is not currently explored by the construction industry and the rare materials recognized as having hygrothermal properties that can provide comfort in summer are little industrialized construction materials based on bio-sourced products such as wood (chips, fibers), hemp (hemp shives), straw or even geo-sourced materials such as earth-based materials (rammed earth, clay bricks, cob, etc.).

In particular, the use of hemp for the production of mortar, coating, prefabricated hemp concrete elements allows optimal humidity regulation in addition to presenting very satisfactory insulating properties and its production has a very interesting carbon footprint. On the other hand, bio-sourced construction materials often have relatively weak mechanical properties which limits their use to insulation, cladding or the formation of wall partitions subject to few mechanical constraints. In addition, the drying times, for example of hemp concrete, are relatively long (e.g. more than 5 days) which further limits their use.

Thus, there is a need for new formulations of fast-setting construction binders with, on the one hand, a low carbon footprint and mechanical properties of concrete at least equivalent or even superior to the mechanical properties of concretes derived from cements commonly used in the construction field (such as CEM I, CEM II, CEM III, CEM IV and CEM V cements defined by standard NF EN 197-1) and, on the other hand, allowing passive regulation of the temperature and humidity of a building incorporating such a construction binder.

[Technical problem]

The invention aims to overcome the drawbacks of the prior art. In particular, the invention aims to propose a construction binder making it possible to obtain a construction material capable of thermal and water regulation while retaining mechanical properties adapted to the constraints of modern constructions. Furthermore, the invention aims to propose for certain applications such a material which also has a rapid setting.

The invention also aims to propose a method for manufacturing a construction binder making it possible to reduce the emission of greenhouse gases, such as carbon dioxide emitted during the preparation of such a construction material, while preserving the suitable mechanical characteristics of said material and giving it hygrothermal regulation properties.

[Brief description of the invention]

To this end, the inventors have developed several solutions to address the 10 drawbacks of the prior art. The preferred solution is detailed below.

The invention relates in particular to a construction binder comprising a raw clay matrix, a deflocculation agent and an activating composition, characterized in that:

- the raw clay matrix contains at least one raw clay from the smectite family;

- at least one raw clay from the smectite family represents at least 20% by weight of the construction binder; and the construction binder comprises less than 15% by weight of Portland cement.

In particular, the invention relates to a construction binder comprising a raw clay matrix, a deflocculation agent and an alkaline activation composition, characterized in that: 20 - it comprises from 2% to 40% by dry weight of the alkaline activation composition;

it comprises at least 40% by weight of raw clay matrix and the raw clay matrix comprises at least one raw clay from the smectite family; the at least one raw clay from the smectite family represents at least 20% by weight of the construction binder; and

- the construction binder comprises less than 15% by weight of Portland cement.

As will be presented in the examples, a construction binder according to the present invention provides water buffer capacities capable of improving the comfort of the inhabitants by thermal and water regulation. In addition, thanks to its mechanical properties combined with these thermal and water regulation properties, the construction binder according to the invention is intended to replace, totally or in part, cement.

Portland. Indeed, the inventors have shown that the presence, at least at a given concentration, of smectite in a construction binder according to the invention makes it possible to achieve very good values of water buffer capacities which are not achievable under these conditions with other raw clays alone such as kaolinite.

Furthermore, as will be shown later, the construction binder makes it possible to achieve mechanical performance identical to Portland cement (e.g. class C12/15; C20/25 or C25/30) while reducing greenhouse gas emissions by 30 to 85%, and providing comfort to residents through thermal and water regulation. In addition, it contains little or no Portland cement. Indeed, as illustrated in the examples, the presence of cement

Portland causes a reduction in water buffer value.

According to other optional characteristics of the construction binder, the latter may optionally include one or more of the following characteristics, alone or in combination:

10, - The raw clay matrix comprises a mixture of at least two types of clays. Preferably, the raw clay matrix comprises at least one raw clay from the smectite family and at least one other clay selected from: lllite; Kaolinite; Vermiculite; Chlorite; Muscovite; Halloysite; Sepiolite or Attapulgite. Indeed, as presented in the examples, a combination of clay makes it possible to obtain better results in terms of water buffer capacity and mechanical resistance.

The raw clay matrix comprises at least one clay having a specific surface area at least equal to 100 m ² /g, for example as measured according to standard NFP 94-068, a specific surface area at least equal to 150 m ² /g; a specific surface area at least equal to 200 m ² /g; or a specific surface area at least equal to 250 m ² /g. More preferably, the raw clay matrix comprises at least two clays having a specific surface area at least equal to 100 m ² /g, a specific surface area at least equal to 150 m ² /g; a specific surface area at least equal to 200 m ² /g; or a specific surface area at least equal to 250 m ² /g. Preferably, the specific surface area can be measured using the protocols described in standards NFP 94-068, or NF

EN 933-9+A1 or ISO 9277:2010. More preferably, the construction binder will comprise at least 20% by weight of a clay having such specific surfaces, even more preferably less than 40% by weight.

. - It comprises at least 10% by weight of raw clay matrix, preferably at least

30%, more preferably at least 40% by weight. Indeed, as will be shown in the examples, from at least 40% by weight of raw clay matrix, the construction binder allows the preparation of construction materials having water buffer capacities (MBV) greater than or equal to 1.3. For example, the raw clay matrix may be present from 40% to 70%, preferably from 40% to 60% by weight of the construction binder.

it further comprises a calcined metal oxide composition; preferably the calcined metal oxide composition being a blast furnace slag. Indeed, ⁵ 218Q1 as presented in the examples, a calcined metal oxide composition makes it possible to increase the mechanical strength without influencing the MBV unlike Portland cement. Preferably, the construction binder comprises at least 20% by weight of the calcined metal oxide composition. In addition, it 5 more preferably has a mass ratio of the raw clay matrix to the calcined metal oxide composition greater than or equal to 1.

. - The activation composition comprises at least 40% by weight of at least one metal oxide corresponding to the oxide of a metal having at least two valence electrons. The activation composition may in particular comprise at least 50% by weight of a metal oxide corresponding to the oxide of a metal having at least two valence electrons. The presence of such a metal oxide at these concentrations in the activation composition makes it possible to increase the water buffer capacity value.

the construction binder comprises at least 10% by weight of at least one metal oxide corresponding to the oxide of a metal having at least two valence electrons. Preferably, the at least 10% by weight may correspond to several different metal oxides. The metal oxides formed with a metal having at least two valence electrons may come from several sources. Preferably, these metal oxides will be contained in the activation composition and/or in the calcined metal oxide composition. Preferably, the construction binder comprises at least 15% by weight of at least one metal oxide corresponding to the oxide of a metal having at least two valence electrons, more preferably at least 20% by weight; even more preferably at least 25% by weight, for example at least 30% by weight. The construction binder may comprise less than 50% by weight of at least one metal oxide corresponding to the oxide of a metal having at least two valence electrons. For example, the construction binder may comprise between 15% by weight and 40% by weight of at least one metal oxide corresponding to the oxide of a metal having at least two valence electrons.

- the construction binder combined with water and aggregates has a water buffer value, measured at the earliest 10 days after manufacture and preferably 28 days, greater than or equal to 0.75, preferably greater than or equal to 1, more preferably greater than or equal to 1.2 and even more preferably greater than or equal to 1.5.

- The deflocculation agent is an organic compound. Preferably, the deflocculation agent comprises a lignosulphonate, a polyacrylate, a humate or a mixture thereof.

It comprises excavated soil containing at least part of the raw clay matrix. The excavated soil can then be considered as excavated clay soil.

It further comprises a composition of at least 20% by weight of calcined aluminosilicates* or in that the composition of metal oxides comprises at least 20% of aluminosilicates.

According to another aspect, the invention relates to a construction material capable of being formed from a construction binder according to the invention, comprising:

at least 2% by weight of at least one raw clay from the smectite family,

- less than 3.75% by weight of Portland cement, and having a water buffer value measured at the earliest 10 days after manufacture greater than or equal to 0.75; preferably greater than or equal to 1. The water buffer value can be measured according to the MBV value measurement methodology as described in the description.

In some aspects, the invention also relates to a construction material formed from a construction binder according to the invention, comprising at least 2% by weight of at least one raw clay of the smectite family, and less than 3.75% by weight of Portland cement.

According to other optional characteristics of the construction material, the latter may optionally include one or more of the following characteristics, alone or in combination:

it comprises at least 2% by weight of a calcined metal oxide composition.

It preferably comprises less than 2% Portland cement, more preferably less than 0.1%, even more preferably it does not comprise Portland cement.

- It contains at least two raw clays.

It comprises at least 5% by weight of at least one metal oxide corresponding to the oxide of a metal having at least two valence electrons.

It has a minimum compressive strength on cylinders at 1 day as measured by the NF EN 206-1 standard greater than or equal to 2 MPa. For example, it may have a minimum compressive strength on cylinders at 28 days as measured by the NF EN 206-1 standard greater than or equal to 2 MPa. In addition, it may have a minimum compressive strength on cylinders at 28 days as measured by the NF EN 206-1 standard less than or equal to 20 MPa.

According to another aspect, the invention relates to a prefabricated element capable of being formed from a construction binder according to the invention, said prefabricated element:

• - having a face with a surface area of at least 1 ^m2 and a thickness of between 0.3 cm and 20 cm;

comprising at least 5% by weight of at least one raw clay from the smectite family, comprising less than 3.75% by weight of Portland cement and

- having a water buffer value, measured at the earliest 10 days after manufacture, greater than or equal to 0.75. The water buffer value can be measured according to the MBV measurement methodology as described in the description.

According to certain aspects, the invention also relates to a prefabricated element formed from a construction binder according to the invention, having a face with a surface area of at least 1 m ² and preferably a thickness of between 0.3 cm and 20 cm; comprising at least 5% by weight of at least one raw clay from the smectite family, and comprising less than 3.75% by weight of Portland cement.

According to other optional characteristics of the prefabricated element, the latter comprises at least 2% by weight of a calcined metal oxide composition.

According to another aspect, the invention relates to a method of preparing a construction material comprising the following steps:

- Providing a construction binder comprising a raw clay matrix comprising at least one raw clay of the smectite family, a deflocculation agent and an activating composition; the at least one raw clay of the smectite family represents at least 20% by weight of the construction binder; and the construction binder comprising less than 15% by weight of Portland cement,

- Add water and aggregates, and

- Mix to obtain a building material.

According to another aspect, the invention relates to a method of producing a prefabrication element prepared from a construction binder, said construction binder comprising a raw clay matrix, an activating composition and a deflocculating agent, said method comprising:

- Providing a construction binder comprising a raw clay matrix comprising at least one raw clay from the smectite family, a deflocculation agent and an activating composition; the at least one raw clay from the smectite family represents at least 20% by weight of the construction binder; and the construction binder comprising less than 15% by weight of Portland cement.

- Mix the construction binder with aggregates and water, and

- Carry out a curing step of the mixture, said curing step comprising a heat treatment of the mixture, preferably at a temperature less than or equal to 100°C, for a duration of between 2 hours and 23 hours.

In particular, the invention relates to a method for producing a prefabrication element prepared from a construction binder, said construction binder comprising a raw clay matrix, an alkaline activation composition and a deflocculation agent, said method comprising:

Providing a construction binder comprising a raw clay matrix comprising at least one raw clay of the smectite family, a deflocculation agent and an alkaline activation composition; the construction binder comprising from 2% to 40% by dry weight of the alkaline activation composition; the at least one raw clay of the smectite family represents at least 20% by weight of the construction binder; and the construction binder comprising less than 15% by weight of Portiand cement, 15 - Mixing the construction binder with aggregates and water, and, - Carrying out a curing step of the mixture, said curing step comprising a heat treatment of the mixture, preferably at a temperature less than or equal to 100°C, for a period of between 2 hours and 23 hours.

Mixing construction binder with aggregates and water produces a building material. Such processes make it possible to produce building materials with a low carbon footprint and water buffering capabilities that can improve the comfort of residents through thermal and water regulation.

In addition, the use of a curing step allows for rapid setting suitable for the manufacture of prefabricated elements.

Furthermore, in embodiments, these prefabrication elements may exhibit, after curing times of twenty-three hours or less, mechanical properties of the concretes at least equivalent or even superior to the mechanical properties of the concretes produced from cements commonly used in the field of construction.

In addition, certain formulations make it possible to obtain a construction material capable of rapid setting, necessary for certain construction methods.

Thus, according to another aspect, the invention relates to a construction material formed or capable of being formed from a construction binder according to the invention.

Depending on other optional characteristics of the construction material, the latter may optionally include one or more of the following characteristics, alone or in combination:

It will comprise at least 2% by weight of at least one raw clay from the smectite family, for example at least 5% by weight; preferably at least 8% by weight, more preferably at least 10% by weight. Indeed, it has been shown that the presence of smectite or a similar clay makes it possible to improve the water buffer capacity.

I

It will contain less than 3.75% by weight of Portland cement.

It will contain at least two raw clays. Indeed, it has been shown that the presence of a combination of clays improves water buffer capacity and mechanical resistance.

- It will further comprise at least 5% by weight of at least one metal oxide corresponding to the oxide of a metal having at least two valence electrons, preferably at least 10% by weight of at least one metal oxide corresponding to the oxide of a metal having at least two valence electrons. This makes it possible to improve the water buffer capacity and the mechanical resistance.

It consists of diatom frustules or plant fibers, preferably hemp shiv.

It has a water buffer value greater than or equal to 0.75, preferably greater than or equal to 1, preferably measured at the earliest 10 days after manufacture.

It has a minimum compressive strength on cylinders at 1 day as measured by standard NF EN 206-1 greater than or equal to 2 MPa, preferably greater than or equal to 3 MPa, preferably greater than 5 MPa. Advantageously, the construction material has a minimum compressive strength on cylinders at 7 days as measured by standard NF EN 206-1 greater than or equal to 8 MPa, preferably greater than or equal to 10 MPa.

Thus, according to another aspect, the invention relates to a prefabricated element capable of being formed from a construction binder according to the invention and having a face with a surface area of at least 1 m ² and a thickness of between 0.3 cm and 20 cm.

Such a prefabricated element advantageously has a water buffer value measured at 10 days greater than or equal to 0.75, preferably greater than or equal to 1, more preferably greater than or equal to 1.2 and even more preferably greater than or equal to 1.5.

Such a prefabricated element advantageously comprises less than 3.75% by weight of Portland cement.

Such a prefabricated element advantageously comprises at least 5% by weight of at least one raw clay from the smectite family.

Such a prefabricated element will be particularly suitable for use inside homes. Indeed, a large exchange surface, combined with a high water buffer value 5, will allow for better regulation. In addition, the thickness can be selected according to the desired level of regulation.

Other advantages and characteristics of the invention will appear on reading the following description given as an illustrative and non-limiting example, with reference to the appended figure 1 representing a diagram of a method for producing a prefabrication element prepared from a construction binder according to the invention.

[Detailed description]

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

The term “Dehydrated” within the meaning of the invention corresponds to a formulation comprising a reduced quantity of water and for example a water content of less than 20% by weight, preferably less than 10%, more preferably less than 5%, more preferably less than 2% and for example less than 1% by weight. The water content can be measured by any method known from the state of the art. It can for example be measured according to standard NF P 94 050 of September 1995 “Determination of the water content by weight of materials: Method by steaming”.

The term “clay matrix” means one or more rock materials based on silicates and/or aluminosilicates with a lamellar structure, said clay matrix being composed of fine particles generally originating 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, vermiculite, metakaolin or mixtures thereof. The expression “raw clay matrix” corresponds, within the meaning of the invention, to a clay matrix which has not undergone a calcination step. In particular, that is to say, it has not undergone any prior heat treatment. For example, this corresponds to a clay matrix which has not undergone a temperature rise above 300°C, preferably above 200°C and more preferably a temperature above 150°C. Indeed, the raw clay matrix can undergo a drying step requiring a temperature rise generally substantially equal to or less than 150°C but no drying step.

218Q1 calcination. A raw clay matrix may preferably comprise a mixture of rock materials which may, for example, consist of kaolinite, illite, smectite, bentonite, chlorite, vermiculite, or mixtures thereof.

For the purposes of the invention, a “deflocculating agent” or “deflocculating agent” may correspond to a compound which, in aqueous suspension, will dissociate aggregates and colloids. Deflocculating agents have, for example, been used in the context of drilling or oil extraction to make clay more fluid and facilitate extraction or drilling.

For the purposes of the invention, “activation composition” may correspond to a composition having the function of accelerating the formation of a compact structure, thus increasing the mechanical resistance of the materials incorporating such an activation composition. In particular, an “alkaline activation composition” comprises at least one base, such as a weak base or a strong base.

The expression "metal oxide composition" may refer, within the meaning of the invention, to a composition comprising metal oxides such as aluminates. In particular, the metal oxide composition comprises more than 25% by weight of metal oxides, preferably more than 30% by weight of metal oxides, more preferably more than 40% by weight of metal oxides and even more preferably more than 45% by weight of metal oxides. For example, the metal oxide composition comprises more than 2% by weight of aluminate, preferably more than 5% by weight of aluminate, more preferably more than 7% by weight of aluminate and even more preferably more than 10% by weight of aluminate. In addition, the metal oxides may correspond to, or comprise, alkaline earth oxides. For example, the metal oxide composition may comprise more than 10% by weight of calcium oxide, preferably more than 20% by weight of calcium oxide, more preferably more than 25% by weight of calcium oxide and even more preferably more than 30% by dry weight of calcium oxide.

The metal oxide composition may comprise chemical species which are not metal oxides. For example, the metal oxide composition may comprise metalloid oxides with, for example, more than 10% by weight of metalloid oxide, preferably more than 20% by weight of metalloid oxide, more preferably more than 25% by weight of metalloid oxide and even more preferably more than 30% by weight of metalloid oxide. These mass concentrations can be easily measured by a person skilled in the art using conventional techniques for measuring metal oxides or metalloid oxides.

In particular, the expression “metal oxide composition” refers to a composition comprising more than 50%, preferably more than 70%, more preferably more than 80% and even more preferably more than 90% of metal oxides and/or metalloid oxides, including aluminates. Preferably, a metal oxide composition will correspond to a slag from metallurgy, such as a blast furnace slag or even fly ash.

As will be detailed later, the “metal oxide composition” is a calcined metal oxide composition. That is to say, it has undergone a high-temperature step. This high-temperature step may be natural or artificial; in this case, it is a high-temperature treatment. The high-temperature step may, for example, correspond to a treatment at a temperature greater than or equal to 500°C, preferably greater than or equal to 750°C and more preferably greater than or equal to 900°C; and even more preferably greater than 1000°C.

The term "binder" or "construction binder" within the meaning of the invention can be understood as a formulation allowing the agglomeration of materials with each other, in particular during the setting and then hardening of a construction material. Thus, it allows in particular the agglomeration of sand and other aggregates with the constituents of the binder. The binder according to the invention is in particular a hydraulic binder, that is to say that hardening takes place upon contact with water.

The term "Portland cement" refers to a hydraulic binder composed mainly of hydraulic calcium silicates whose setting and hardening is made possible by a chemical reaction with water. Portland cement generally contains at least 95% clinker and a maximum of 5% secondary constituents such as alkalis (Na2O, _K2O ), magnesia (MgO), gypsum ( _CaSCL2H2O ) or various traces of metals.

A “construction material” within the meaning of the invention generally corresponds to elements comprising the constituents of the binder as well as aggregates and other additives. In particular, a construction material within the meaning of the invention meets the criteria of standard NF EN 206-1. It can take different forms such as mortar, concrete or prefabricated elements such as concrete blocks. A “quick-setting construction material” can in particular take the form of a construction material which, 24 hours after the addition of water, has a minimum compressive strength on cylinders as measured by standard NF EN 206-1 greater than or equal to 2 MPa; preferably greater than or equal to 3 MPa; more preferably greater than or equal to 5 MPa.

The term "air entrainer" refers to an adjuvant intended to be incorporated into a construction binder according to the invention and whose main function is to generate porosities of uniform size within the construction binder once the latter has set. Such an adjuvant may, for example, correspond to surfactants such as alkyl ether sulfates.

The term "moisture buffer value" or "MBV" represents the capacity of a material to exchange moisture with its environment. It allows the dynamic hygrothermal behavior of the material in question to be estimated and is used to determine thermal comfort in the field of construction and more specifically the regulation of the indoor humidity of a room or building. MBV is expressed in g/m ² .%RH and indicates the average quantity of water that is exchanged by sorption or desorption when the surfaces of the material are subjected to variations in relative humidity (RH) over a given time.

The water buffer value can be measured by any method known to the person skilled in the art. For example, the person skilled in the art may refer to the method described in “Durability and hygroscopic behavior of biopolymer stabilized earthen construction materials” Construction and Building Materials 259 (2020). In particular, the samples may be placed in a climatic chamber at 23°C and 33% relative humidity and left until they have a constant mass (for example, a climatic chamber model MHE 612). Under these conditions, the samples are equilibrated after 15 days of storage. The samples are then exposed to high humidity cycles (75% RH for 8 hours) followed by a low relative humidity cycle (33% RH for 16 hours). The samples are weighed at regular intervals with a laboratory balance accurate to 0.01g. After two stable cycles, the samples are removed from the climatic chamber.

MBV =

Am

S x A%RH where Am is the change in sample mass due to change in relative humidity, S is the total exposure area and A%RH is the difference between the humidity levels.

The term “substantially equal” within the meaning of the invention corresponds to a value varying by less than 20% compared to the compared value, preferably by less than 10%, even more preferably by less than 5%.

The expression "prefabrication element" or "prefabricated elements" within the meaning of the invention may correspond to construction elements that have undergone a curing stage, such as concrete block-type elements that can be combined in a modular manner to manufacture a building. These prefabrication elements may include a frame (e.g., beams, panels, stairs) or not (e.g., blocks, blocks, tiles, plates).

The expression "specific surface area" within the meaning of the invention may correspond to an adsorption capacity of clays. It can be measured by the French standard NFP 94-068 indicating a methodology for determining the methylene blue value of a soil or rock material by means of the methylene blue test. The specific surface area can also be measured according to the standard NF EN 933-9+A1. Indeed, there is a correlation, demonstrated as early as 1950 by Dyal and Hendricks, 1950, between the adsorption of the methylene blue molecule (in g/100 g) via electrostatic interactions, and the specific surface area measurements of the clay material. In addition, the measurement of the specific surface area can also be measured via the BET method (Brunauer, Emmett and Teller). This method may preferably be implemented according to the recommendations of the ISO 9277:2010 standard. Briefly, the specific surface area is estimated from the amount of nitrogen adsorbed in relation to its pressure at the boiling point of liquid nitrogen and under normal atmospheric pressure. The information is interpreted according to the Brunauer, Emmett and Teller model (BET method).

The expression "excavated clayey soil" corresponds, within the meaning of the invention, to a clayey soil obtained following a step where the ground has been dug, for example during grading and/or earthworks operations, with a view to constructing, building or backfilling. For example, the excavated clayey soil may correspond to quarry fines, dredging sediments, drilling/washing muds. In particular, when these fines, muds or sediments comprise clays having a specific surface area greater than 100 m ² /g, preferably greater than 200 m ² /g or even clays from the smectite family; preferably at contents greater than 20% by weight of the clay matrix, then they are particularly suitable for the present invention. In particular, within the meaning of the invention, the excavated clayey soil may or may not be moved outside the production site. Preferably and according to an advantage of the invention, the excavated earth is used on the production site or at a distance of less than 200 km, preferably less than 50 km. Furthermore, advantageously, the clayey earth excavated in the context of the invention is a raw excavated clayey earth, that is to say that it has not undergone a calcination step. In particular, that is to say that it has not undergone any prior heat treatment. For example, this corresponds to a clayey earth that has not undergone a temperature rise greater than 300°C, preferably greater than 200°C and more preferably a temperature greater than 150°C. Indeed, the raw clayey earth can undergo a heating step requiring a temperature rise generally substantially equal to 150°C but no calcination step. A calcination step may, for example, correspond to a heat treatment at more than 600°C for at least one hour. Clay as conventionally used has a relatively constant particle size profile with sizes less than 2 μm. An excavated clayey soil may have different particle size profiles. In the context of the invention, an excavated clayey soil may contain particles larger than 2 μm, preferably larger than 20 μm, preferably larger than 50 μm and for example larger than 75 μm as determined according to standard ASTM D422-63. Preferably, the excavated clayey soil does not contain aggregate larger than 2 cm as determined according to standard NF EN 933-1.

The construction industry must evolve to increase productivity while addressing new societal challenges. In this context, manufacturers have proposed so-called more environmentally friendly cement blends, for example, containing 50% Portland cement, 30% slag, and 20% fly ash; high-performance concretes have also been proposed that can contain superplasticizers, such as self-compacting concrete or cellular concrete containing gypsum, lime, cement, and sand.

However, these solutions do not allow productivity (i.e. speed of setting and mechanical resistance) to be combined with a significant reduction in the carbon footprint and comfort (in particular control of temperature and humidity level) for users.

To address this, the inventors have developed a new solution involving new construction binder formulations. This new solution has the advantage of having a much lower carbon footprint than most of the construction binders, or hydraulic binders, most widely used in the world today (e.g. Portiand Cement). In addition, these solutions ensure optimal regulation of the ambient temperature and humidity level and can in certain cases ensure rapid setting of the construction material comprising such a binder formulation. To this end, a binder according to the invention consists of a raw clay matrix, which has not undergone a calcination step, an energy-intensive step which also generates the emission of greenhouse gases and more particularly carbon dioxide. The invention relates in particular to a construction binder comprising a raw clay matrix, a deflocculation agent and an activating composition, characterized in that the raw clay matrix comprises at least smectite, montmorillonite or bentonite, preferably more than 10% by weight of a clay from the smectite family.

As will be presented in the examples, a method according to the invention makes it possible to manufacture construction elements from a binder comprising a high concentration of raw clay matrix (generally greater than 10%, preferably greater than or equal to 20%), having a mechanical resistance at 28 days greater than 10 MPa, preferably greater than 12 MPa and having a MBV greater than 0.7, preferably greater than

1, and more preferably greater than 1.3 and even more preferably greater than 1.5.

In particular, the inventors have developed construction binder compositions for forming construction materials having a minimum compressive strength on cylinders as measured by standard NF EN 206-1, at 28 days greater than or equal to 12 MPa, preferably greater than 15 MPa and a water buffer value greater than or equal to 0.7, preferably greater than or equal to 1, more preferably greater than or equal to 1.2 and even more preferably greater than or equal to 1.5.

We will present in detail the general and preferred characteristics of each of the constituents of the construction binder according to the invention. These embodiments are equally applicable to the construction binder according to the invention as to the other aspects of the present invention such as the methods, the construction material as such (including prefabricated elements) or the uses of the construction binder and the construction material.

Raw clay matrix

The raw clay matrix may for example comprise at least one mineral species 10 selected from: lllite, Kaolinite, Smectite, Bentonite, Vermiculite, Chlorite, Muscovite, Halloysite, Sepiolite, and Attapulgite.

In particular, the raw clay matrix comprises smectite, preferably montmorillonite. In particular, the clay matrix comprises at least 10% by weight of smectite, preferably montmorillonite, preferably at least 20% by weight.

Indeed, the inventors have shown that, if the raw clay matrix comprises at least one raw clay from the smectite family and in particular when the at least one raw clay from the smectite family represents more than 10% by weight of the construction binder, preferably at least 20% by weight of the construction binder, then the construction binder allows the preparation of construction materials combining mechanical properties and water buffer capacity.

The smectite family includes montmorillonites and bentonite.

Preferably, the raw clay matrix comprises at least two types of clay selected from: llite; Smectite, preferably Montmorillonite; Kaolinite; Bentonite;

Vermiculite; Chlorite; Muscovite; Halloysite; Sepiolite or Attapulgite. This includes so-called interstratified clays which are complex combinations of several clays. Even more preferred, the raw clay matrix comprises at least one mineral species selected from: Kaolinite, Illite, Smectite, Bentonite, Chlorite and Vermiculite.

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

Clay Matrix Type of clay Composition

Crude llite (K,H ₃ 0)(AI,Mg,Fe)2(Si,AI)40io[(OH)2,(H ₂ 0)] Smectite (Na,Ca)o.3(AI,Mg)2Si40 ₁₀ (OH)2, n H ₂ O Kaolinite AI ₂ SÎ2O ₅ (OH)4 Bentonite (Na,Ca)o,3(AI,Mg)2Si ₄ Ow(OH)2 Vermiculite (Mg,Ca)o.7(Mg,Fe,AI)6(AI,Si)a022(OH)4. n H ₂ O Chlorite (Fe,Mg,AI) ₆ (Si,AI)4Oi ₀ (OH) _a Muscovite KAl2(AISi ₃ Oio) (OH,F) ₂ Halloysite AI ₂ SÎ2O ₅ (OH)4 Sepiolite Mg4Si6Oi5(OH) ₂ , _nH2O Attapulgite (Mg,AI,Fe ³⁺ ) ₅ [Si ₈ 0 ₂ o](OH) ₂ (OH2) ₄ n H ₂ O

As has been explained, according to a preferred embodiment, a construction binder according to the invention will comprise at least two different types of clay and will comprise smectite.

The type of clay may be determined by methods known to the person skilled in the art.

In particular, it will be possible to use X-ray diffractometry. For example, the following conditions can be used:

- Equipment: Diffractometer, for example a BRUKER D8 ADVANCE (Bragg-Brentano geometry); for example with the following settings: Copper tube (λ Kai ~ 1.54 A) Generator power: 40 kV, 40 mA; Primary optics: slit

10. fixed 0.16°; Soller slit 2.5°; Secondary optics: Soller slit 2.5°; Detector

LynXeye XE-T

Acquisition parameters: Scanning from 4 to 90°2θ; Scanning speed of 0.03°20/second, Counting time: 480 seconds per step; Rotating sample.

For example, a construction binder according to the invention comprises at least 10% by weight of raw clay matrix, preferably at least 20% by weight of raw clay matrix, more preferably at least 30% by weight of raw clay matrix and even more preferably at least 40% by weight of raw clay matrix. For example, at least 50% by weight of raw clay matrix or at least 60% by weight of raw clay matrix.

Furthermore, preferably, a construction binder according to the invention comprises at most 80% by weight of raw clay matrix, more preferably at most 70% by weight of raw clay matrix.

Thus, in particular, a construction binder according to the invention may comprise between 20 and 80% by weight of raw clay matrix, preferably between 30 and 80% by weight or between 40 and 80% by weight of raw clay matrix, more preferably between 40 and 70% by weight of raw clay matrix.

Preferably, the raw clay matrix of a construction binder according to the invention comprises at least 20% by weight of smectite, for example at least 30% by weight of smectite, preferably at least 40% by weight of smectite, more preferably at least 50% by weight of smectite and even more preferably at least 60% by weight of smectite.

In particular, a clay matrix according to the invention may comprise between 20 and 80% by weight of smectite, preferably between 30 and 70% by weight of smectite or between 40 and 60% by weight of smectite, more preferably between 40 and 60% by weight of smectite.

Preferably, the smectite may be Montmorillonite.

More preferably, the raw clay matrix of a construction binder according to the invention comprises at least one raw clay from the smectite family and at least one other raw clay selected from Kaolinite, lllite, Chiorite and Vermiculite. Even more preferably, the raw clay matrix of a construction binder according to the invention comprises smectite and at least one other raw clay selected from Kaolinite, lllite, Bentonite, Montmorillonite, Chiorite and Vermiculite.

Even more preferably, the construction binder comprises excavated earth comprising the raw clay matrix. It may comprise at least 2% by weight of silt particles, preferably at least 4% by weight, more preferably at least 6% by weight. The silt particles are in particular particles having a diameter of between 2 μm and 125 μm, preferably between 2 and 50 μm.

The excavated clay soil may advantageously have been pre-treated, said pre-treatment being selected from: crushing, sorting, sieving and/or drying of the excavated clay soil. The pre-treatment may for example include fractionation.

The construction binder according to the invention has the advantage of being able to contain a high quantity of raw clay matrix without this altering either the hygroscopic properties or the mechanical properties of the construction materials, making it possible to produce construction materials which, in addition to water buffering capacities, in certain cases have an improved setting time compared to the construction materials commonly used.

Deflocculation agent

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

In the context of the invention, the deflocculation agent is in particular a nonionic surfactant such as a polyoxyethylene ether. The polyoxyethylene ether may for example be selected from: a lauryl poly(oxyethylene) ether.

The deflocculating agent can also be an anionic agent such as an anionic surfactant.

In particular, the anionic agent may be selected from: alkylaryl sulfonates, amino alcohols, fatty acids, humates (e.g. sodium humates), carboxylic acids, lignosulfonates (e.g. sodium lignosulfonates), polyacrylates, carboxymethylcelluloses and mixtures thereof.

The deflocculation agent can also be a polyacrylate. It can then be selected, for example, from sodium polyacrylate and ammonium polyacrylate.

The deflocculating agent may also be an amine selected for example from: 2-amino-2-methyl-1-propanol; mono-, di- or triethanolamine; isopropanolamines (120* Amino-2-propanol, diisopropanolamine and triisopropanolamine) and N-alkylated ethanolamines.

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.

The deflocculating agent may be an organic deflocculating agent. According to the present invention, an organic deflocculating agent comprises at least one carbon atom and preferably at least one carbon-oxygen bond. Preferably, the deflocculating agent is selected from: a lignosulphonate (e.g. sodium lignosulphonate), a polyacrylate, a humate, a polycarboxylate such as an ether polycarboxylate, and mixtures thereof. More preferably, the deflocculating agent comprises humate, lignosulphonate and/or polyacrylate.

The deflocculating agent is preferably in powder form (such as a salt).

However, the invention cannot be limited to the deflocculating agents mentioned above. Any type of deflocculating agent known to those skilled in the art can be used instead of the aforementioned deflocculating agents.

In particular, the deflocculation 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. Furthermore, the deflocculation agent may represent at most 5% by weight of the raw clay matrix.

In particular, the deflocculating agent represents at least 0.1% by weight of the construction binder, preferably at least 0.5% by weight of the construction binder. Furthermore, the deflocculating agent may represent at most 5% by weight of the construction binder, preferably at most 4% by weight of the construction binder, more preferably at most 3% by weight of the construction binder, and even more preferably at most 2% by weight of the construction binder.

Indeed, with such concentrations of deflocculation agent, a construction binder according to the invention can then be used in combination with an activation composition to form a material with advantageous hygrothermal and mechanical properties. In addition, a certain level of deflocculation agent should not be exceeded in order to avoid degradation of the mechanical properties of the construction material. Too high a concentration of deflocculation agent in combination with the raw clay matrix and the activation composition may degrade the mechanical performance and/or the performance of MBV.

Activation composition

The activating composition is preferably an alkaline activating composition.

An alkaline activating composition comprises at least one base, such as a weak base or a strong base. The alkaline activating composition may preferably comprise one or more compounds having a pKa greater than or equal to 8, more preferably greater than or equal to 10, more preferably greater than or equal to 12, even more preferably greater than or equal to 14.

Thus, the alkaline activating composition may comprise sulfates, hydroxides, carbonates, lactates, organophosphorus compounds or combinations thereof.

Preferably, the alkaline activation composition comprises hydroxides.

In particular, the alkaline activating composition may comprise a mixture of sodium/calcium sulfate and sodium/calcium chloride.

Preferably, the alkaline activation composition comprises carbonates. In particular, the alkaline activation composition may comprise a mixture of sodium or potassium silicate and sodium or potassium carbonate. The activation composition may also comprise an alkaline compound, preferably a strong base.

Advantageously, the activation composition comprises an oxide of a metal having at least two valence electrons. Indeed, in such a configuration, the water buffer value is improved compared to an alkaline activation composition based on sulfates, hydroxides, carbonates, lactates, organophosphorus compounds or combinations thereof. In particular, the activation composition may comprise at least 40% by weight of at least one metal oxide corresponding to the oxide of a metal having at least two valence electrons.

For example, the at least 40% by weight may correspond to several different metal oxides. However, preferably, the activation composition, preferably when it is an alkaline activation composition, may comprise a single oxide of a metal having at least two valence electrons or more than 50% by weight of this metal oxide.

Preferably, the activation composition comprises at least 50% by weight of at least one metal oxide corresponding to the oxide of a metal, or of an alkaline earth metal, having at least two valence electrons, more preferably at least 60% by weight; even more preferably at least 80% by weight.

The presence of metal oxides, for example having at least two 20 valence electrons, can be identified by X-ray fluorescence spectrometry (XRF) and/or X-ray diffraction (XRD).

The alkaline activating composition may comprise an organophosphorus compound such as sodium tripolyphosphate. Preferably the organophosphorus compound represents at least 2% by weight of the construction binder.

Preferably, the alkaline activation composition comprises a lactate such as sodium, potassium, and/or lithium lactate.

As will be described below, the activating composition may be a liquid composition. In particular, the activating composition may be an aqueous composition. As will be described below, its use may be combined with the addition of water when forming * a construction binder according to the present invention. However, alternatively, the activating composition is in solid form, for example in powder form.

The indicated percentage of alkaline activation composition corresponds to the dry weight of the composition.

The activation composition is, for example, present at a content of at least 2% by dry weight of the construction binder.

Preferably, the construction binder comprises from 2% to 50% by dry weight of an alkaline activating composition. More preferably, the construction binder comprises from 2% to 40% by dry weight of an alkaline activating composition. Even more preferably, the construction binder comprises from 10% to 20% by dry weight of an alkaline activating composition.

As will be illustrated in the examples, the concentration of alkaline activation composition required can vary widely depending on its composition. Thus, the construction binder according to the invention may comprise from 20% to 40% by weight of an alkaline activation composition. This is particularly the case when the alkaline activation composition comprises hydroxides. Alternatively, the construction binder according to the invention may comprise from 2% to 10% by weight of an alkaline activation composition. This is particularly the case when the alkaline activation composition comprises carbonates.

Finally, the construction binder according to the invention may comprise from 10% to 30% by weight of an alkaline activation composition, preferably from 15% to 25% by weight of an activation composition.

The presence of constituents of the activation composition can be identified by 20 spectrometry methods which will depend on the activation composition used. For example, it will be possible to identify constituents of the composition in a construction material by infrared spectrometry.

Calcined metal oxide composition

As will be shown in the examples, a construction binder according to the invention preferably comprises less than 15% by weight of Portland cement, more preferably less than 10% by weight, less than 8% by weight, less than 5% by weight, less than 3% by weight, less than 2% by weight and even more preferably does not comprise Portland cement.

"

In fact, the presence of Portland cement leads to a reduction in the water buffer value.

A metal oxide composition advantageously comprises metal oxides selected from: iron oxides such as FeO, FesCU, Fe ₂ O3, alumina AI2O3, manganese(II) oxide MnO, titanium(IV) oxide TiO ₂ , magnesium oxide MgO and mixtures thereof.

It may also contain metal oxides selected from: calcium oxides and magnesium oxides.

² 21861 «

A composition of metal oxides may also include aluminosilicates.

The composition of metal oxides is for example selected from:

blast furnace slag, pozzolans such as volcanic ash, fly ash, silica fume or metakaolin, ash from plant materials such as rice ash,

- bauxite residues, or combinations thereof.

Preferably, in the calcined metal oxide composition, the metal oxides are transition metal oxides. The metal oxides may preferably originate from a composition of blast furnace slags, for example formed during the production of cast iron from iron ore.

The inventors have identified the importance of the mass quantity of metal oxides in combination with the raw clay matrix. Preferably, the construction binder comprises at least 10% by weight of metal oxides.

For example, a construction binder according to the invention may comprise at least 15% by weight of a blast furnace slag composition.

Advantageously, the construction binder comprises, for example, 10% by weight of aluminosilicate, preferably at least 10% by weight, more preferably at least 20% by weight, resulting from a calcination process.

For example, the construction binder may comprise a composition of at least 20% by weight of calcined aluminosilicates or the calcined metal oxide composition comprises aluminosilicates representing at least 20% by weight of the construction binder. The aluminosilicates come, for example, from alumina, red mud, fly ash, blast furnace slag or metakaolin.

Without being limited by theory, a balance between the amount of the calcined metal oxide composition and the raw clay matrix will, in combination with the alkaline activation composition, strengthen the bonds between the clay layers so as to provide its mechanical properties to the binder while retaining, thanks to the deflocculant and the type of clay selected, optimal hygrothermal properties. This is particularly true when the clay matrix comprises smectite, which the inventors have discovered to be particularly suitable, in combination with a deflocculating agent and an activation composition, for the preparation of construction materials having a high MBV value (e.g. >0.7, or preferably greater than 1).

Furthermore, the inventors identified that certain values of ratio between the mass quantity of metal oxide composition and the mass quantity of raw clay matrix allowed an adequate balance between mechanical resistance, hygrometric capacity and speed of setting.

Advantageously, the composition of metal oxides and the raw clay matrix are present in the construction binder so that a mass ratio of the raw clay matrix to the composition of metal oxides is less than or equal to 6, preferably less than or equal to 4, more preferably less than or equal to 2.

For example, the metal oxide composition and the raw clay matrix are present in the construction binder such that a mass ratio of the raw clay matrix to the metal oxide composition is preferably greater than or equal to 0.3; more preferably greater than or equal to 0.5 and even more preferably greater than or equal to 1. For example, the metal oxide composition and the raw clay matrix are present in the construction binder such that a mass ratio of the raw clay matrix to the metal oxide composition is from 0.3 to 3, more preferably from 1 to 3, even more preferably from 1 to 2.

Advantageously, the composition of metal oxides and the deflocculation agent are present in the construction binder so that a mass ratio of the composition of metal oxides to the deflocculation agent is greater than or equal to 12, preferably greater than or equal to 15.

In particular, the metal oxide composition, also called calcined metal oxide composition, represents from 20% to 70% by weight of the construction binder.

Preferably, the metal oxide composition, also called calcined metal oxide composition, represents from 35% to 65% by weight of the construction binder.

More preferably, the metal oxide composition, also called calcined metal oxide composition, represents from 40% to 65% by weight of the construction binder.

The presence of constituents of the calcined metal oxide composition may be identified by spectrometric methods that will depend on the calcined metal oxide composition used. For example, it will be possible to identify constituents of the calcined metal oxide composition in a construction material by scanning electron microscopy, by scanning electron microscopy coupled with a microprobe 35 or by measurement by X-ray fluorescence spectrometry (XRF) and/or by X-ray diffraction (XRD).

The construction binder may contain many other compounds. For example, it may include an adjuvant, preferably representing at least 1% by weight of said binder. In particular, the adjuvant is an air entrainer. The person skilled in the art may, for example, use those known in conventional concretes.

As detailed, according to the inventors, it has never been proposed to combine blast furnace slag, fly ash or equivalent with raw clay, and an activation composition, preferably alkaline, to produce a construction material having a good MBV (i.e. greater than or equal to 0.7) and capable of rapid setting. In particular, it has never been proposed to combine blast furnace slag, fly ash or equivalent with a clay matrix comprising at least one raw clay from the smectite family, the at least one raw clay from the smectite family representing at least 20% by weight of the construction binder, and an activation composition, preferably alkaline, to produce a construction material having a good water buffer capacity (MBV) and capable of rapid setting. These construction binder compositions further comprise less than 15% by weight of Portland cement.

Furthermore, among all the formulations, compositions or binders according to the invention which can be used effectively in a method according to the invention, the inventors have identified certain 20 construction binder formulations which are novel as such and have a reduced carbon footprint, rapid setting, hygrothermal properties and high mechanical performance. These novel and particularly effective formulations are part as such of the subject of the present invention.

The invention also relates to a construction binder comprising a raw clay matrix, a deflocculation agent, an activating composition, said construction binder comprising:

at least 40% by weight of raw clay matrix, said raw clay matrix comprises at least one raw clay from the smectite family; and the at least one raw clay from the smectite family represents at least 20% by weight of the construction binder; and less than 15% by weight of Portland cement.

The invention also relates to a construction binder comprising a raw clay matrix, a deflocculation agent, an activating composition, said construction binder comprising:

at least 40% by weight of raw clay matrix, said raw clay matrix comprises at least one raw clay from the smectite family; and the at least one raw clay from the smectite family represents at least 20% by weight of the construction binder;

- at least 35% by weight of blast furnace slag; and less than 15% by weight of Portland cement.

The invention also relates to a construction binder comprising a raw clay matrix, a deflocculation agent, an activating composition, said construction binder, 10 comprising:

at least 40% by weight of raw clay matrix, said raw clay matrix comprises at least one raw clay from the smectite family; and the at least one raw clay from the smectite family represents at least 20% by weight of the construction binder;

- less than 15% by weight of Portland cement; and * - at least 0.5% by weight of deflocculation agent, the deflocculation agent comprising an organic compound selected from: humates, lignosulfonate and polyacrylate.

I

The invention also relates to a construction binder comprising a raw clay matrix, a deflocculation agent, an activating composition, said construction binder comprising:

at least 40% by weight of raw clay matrix, said raw clay matrix comprises at least one raw clay from the smectite family; and at least one clay!

raw material from the smectite family represents at least 20% by weight of the construction binder;

less than 15% by weight of Portland cement; and

- at least 15% by weight of activating agent, the activating agent comprising at least 70% by weight of at least one metal oxide corresponding to the oxide of a metal having at least two valence electrons.

According to another aspect, the invention relates to a use, for the preparation of a construction binder, of a raw clay matrix comprising a mixture of at least two types of clays having a specific surface area at least equal to 100 m ² /g, in combination with a deflocculation agent and an activating composition. In particular, the raw clay matrix comprises at least one clay having a specific surface area at least equal to 100 m 2 /g.

..... . . . _______xJ m ² /g, a specific surface area at least equal to 150 m ² /g; a specific surface area at least equal to 200 m ² /g; or a specific surface area at least equal to 250 m ² /g. Preferably, the raw clay matrix comprises at least two clays having a specific surface area at least equal to 100 m ² /g, a specific surface area at least equal to 150 m ² /g; a specific surface area at least equal to 200 m ² /g; or a specific surface area at least equal to 250 m ² /g.

The invention also relates to a use, for the preparation of a construction binder, of a raw clay matrix comprising at least one raw clay from the smectite family, the at least one raw clay from the smectite family representing at least 20% by weight of the construction binder, in combination with a deflocculation agent and an activation composition; and the construction binder comprising less than 15% by weight of cement

Portland.

The construction binder according to the invention can be used to produce covering 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.

The construction binder according to the invention can be used 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.

The construction binder according to the invention can be used 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, more preferably less than 1.0 kg/L, more preferably less than 0.7 kg/L).

The invention also relates to the use of the construction binder according to the invention, for implementing additive manufacturing. In particular, the implementation of additive manufacturing can be carried out by means of 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.

The construction binder according to the invention can be used 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 mastic, glue or sealing mortar.

According to another aspect, the invention relates to a method for preparing a construction binder. Such a method according to the invention relates in particular to the production of a construction binder making it possible to generate construction materials having high water buffer capacities (i.e. greater than 0.75).

As before, the raw clay matrix may contain at least one mineral species selected from: lllite; Smectite preferably Montmorillonite; Kaolinite; Bentonite; Vermiculite; Chlorite; Muscovite; Halloysite; Sepiolite or Attapulgite. This includes so-called interstratified clays which are complex combinations of several clays.

The method particularly comprises mixing a raw clay matrix, a deflocculation agent and an activating composition. The raw clay matrix comprises at least one raw clay of the smectite family and the at least one raw clay of the smectite family represents at least 20% by weight of the construction binder. In addition, the construction binder preferably comprises less than 15% by weight of Portland cement.

The method may comprise a homogenization or mixing step so as to obtain a construction binder. This homogenization or mixing step may in particular last at least 45 seconds, preferably at least 60 seconds, more preferably at least 90 seconds; and for example less than 30 minutes; preferably less than 10 minutes; more preferably less than 5 minutes.

After the mixing step, the process according to the invention may include the addition of additives or materials making it possible to modify the mechanical properties of the final construction material.

The added materials may, for example, be recycled or non-recycled aggregates, selected from fillers, powders, sand, gravel, gravels, and/or fibers, and possibly pigments. Generally, aggregates may be sand or sand and other aggregates such as gravel, gravels, pebbles, hemp shiv and/or other plant aggregates.

The process may also involve the addition of a plasticizer or superplasticizer.

The method may also include the addition of fibers. The fibers are, for example, selected from: plant fibers such as cotton, linen, hemp, cellulose, bamboo, miscanthus fibers, synthetic fibers such as metal, glass, carbon, polypropylene fibers and their mixtures. The presence of ^z 21861 fibers can allow the formation of a building material with improved mechanical and insulating properties.

The process may also include the addition of aggregates. Aggregates are selected, for example, from: gravel, crushed concrete, recycled concrete and their mixtures.

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

i

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

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

In some embodiments, the construction binder will be used for the preparation i

I of prefabrication element.

Thus, according to another aspect, the invention relates to a method for producing a prefabricated element. In this context, it is important, in addition to the water buffering capacities, that the construction binder can allow rapid setting of the construction material.

The prefabricated element is in particular prepared from a construction binder comprising a raw clay matrix, a deflocculation agent and an activation composition with added aggregates and water.

In particular in the construction binder used in this method, the raw clay matrix comprises at least one raw clay of the smectite family; the at least one raw clay of the smectite family represents at least 20% by weight of the construction binder; and the construction binder comprises less than 15% by weight of Portland cement. As mentioned the method benefits from the embodiments of the construction binder thus, more preferably the construction binder comprises less than 10% by weight of Portland cement, less than 8% by weight, less than 5% by weight, less than 3% by weight, less than 2% by weight and even more preferably does not comprise Portland cement.

As illustrated in Figure 1, a method 100 according to the invention comprises the following steps: a step 110 of providing a construction binder, a step 120 of mixing the constituents of the binder for construction material with the aggregates and water, and a step 130 of curing the mixture.

As illustrated, the method according to the invention may also comprise steps of preparing 101 molds, demolding 140 of the prefabrication element and drying 150 of the prefabrication element.

Now, as will be illustrated in the examples, the inventors have determined selections of clays and conditions of use making it possible to obtain construction materials allowing high levels of mechanical resistance and rapid setting despite high levels of raw clay. In particular, under the selected conditions, the clay matrix may be present at more than 10% by weight of the binder for construction material, preferably it is present at more than 20% by weight of the binder for construction material.

It is therefore possible to obtain materials that can have a water buffer capacity greater than or equal to 0.75, a low carbon footprint while respecting the productivity requirements of the construction industry.

In particular, as will be illustrated in the examples, the raw clay matrix comprises at least one raw clay from the smectite family. It is when the raw clay matrix comprises these clays (one or more) that the best results in terms of water buffer capacity are obtained.

In addition to the choice of clays to be used, the inventors determined that to obtain a construction material with a high water buffer capacity while exhibiting rapid setting, it is necessary to add a deflocculating agent and carry out heat treatment.

Thus, advantageously, within the framework of a method 100 for producing a prefabrication element according to the invention, the curing step 130 comprises a heat treatment of the mixture. Indeed, the combination of carrying out a heat treatment and the presence of clays from the smectite family makes it possible to obtain a construction material having water buffer capacities greater than or equal to 0.75 while exhibiting rapid setting.

As mentioned and illustrated in Figure 1, a method 100 for producing a prefabrication element according to the invention may include steps 101 of preparing molds, with, for example, the use of a release agent and formwork oil, the use of shims for reinforcement, or even the use of systems allowing hermetic coverage of the parts or curing products.

In addition, the method according to the invention may comprise a first step of preparing a construction binder mixture. The step of preparing the construction binder mixture may, for example, comprise dry mixing. Indeed, a majority or all of the constituents of the construction binder may be used in dehydrated form.

Alternatively, a portion of the constituents may be mixed dry while another 10 portion of the constituents is added in liquid form.

In particular, the method according to the invention comprises a step 120 of mixing the constituents of the construction binder with aggregates and water.

The water to dry matter mass ratio of the composition, herein referred to as construction binder, is preferably controlled. The water/dry matter mass ratio is preferably less than 1, more preferably less than or equal to 0.6 and even more preferably less than or equal to 0.5. This ratio does not take into account the quantity of aggregates added.

Typically, aggregates may correspond to natural aggregates, artificial aggregates or recycled aggregates. Aggregates may also include mineral aggregates, i.e., those mainly made up of mineral matter, and/or plant aggregates, i.e., those mainly made up of plant-based material. Aggregates may also include marine aggregates, i.e., those mainly made up of organic or inorganic matter from the seabed, such as siliceous aggregates and calcareous substances (e.g., maerl and shell sand). Mineral aggregates may, for example, correspond to sand, gravel, gravel, fillers (or fine materials), powders, fossilized waste and their combination.

Plant aggregates may, for example, correspond to wood (chips or fibers), hemp, straw, hemp shiv, miscanthus, sunflower, typha, corn, flax, rice husks, wheat husks, rapeseed, algae, bamboo, cellulose wadding, defibrated fabric and their combinations.

In particular, when a construction material or a prefabricated element according to the invention comprises plant aggregates, it preferably comprises at least 10% by weight of plant aggregates, preferably at least 15% by weight of plant aggregates, more preferably at least 20% by weight of plant aggregates, and even more preferably at least 25% by weight of plant aggregates. Generally, when plant aggregates are used, the construction material or prefabricated element according to the invention will preferably comprise at most 60% by weight of plant aggregates, and more preferably at most 50% by weight of plant aggregates. For example, the construction material or prefabricated element according to the invention may preferably comprise between 10% and 50% by weight of plant aggregates and more preferably between 15% and 35% by weight of plant aggregates. When using plant aggregates in the compressed concrete block according to the invention, they can be combined with mineral aggregates such as sand. This can improve mechanical performance.

Such a mixing step can advantageously but not exclusively be carried out in a device selected from: a mixer and a concrete mixer truck or more generally within any device suitable for mixing a construction binder. A dispersion device using, for example, ultrasound can be used.

Furthermore, the mixing step 120 can be carried out over a period of at most 24 hours, preferably at most 12 hours, more preferably at most 6 hours. Advantageously, in the context of a method 100 for manufacturing a prefabrication element, it can be only several tens of minutes and therefore less than one hour or even a few tens of seconds. Indeed, the mixtures can be carried out in the context of manufacturing on a press, vibrating or not, where the mixing is carried out a few seconds before filling the molds.

Before the optional curing step 130, during or before the mixing step 120, the method 100 according to the invention may include the addition of additives or materials making it possible to modify the mechanical properties of the final construction material.

Thus, the process may also involve the addition of a plasticizer or a superplasticizer.

The method 100 may also include the addition of fibers. The fibers are, for example, selected from: plant fibers such as cotton, linen, hemp, cellulose, bamboo, miscanthus fibers, synthetic fibers such as metal, glass, carbon, polypropylene fibers and their mixtures. The presence of fibers advantageously allows the formation of a construction material with improved mechanical and insulating properties, while retaining a water buffer capacity.

The method 100 may also include the addition of aggregates. The aggregates are, for example, selected from: gravel, crushed concrete, recycled concrete and mixtures thereof.

The method 100 may also include the addition of an additive. The additive is, for example, selected from: a synthetic or natural rheological maintaining agent, an anti-shrinkage agent, a water-retaining agent, an air-entraining agent, a synthetic resin and mixtures thereof.

The method 100 according to the invention may also include a step 130 of curing the mixture.

The curing step 130 is generally known to those skilled in the art who will be able to implement it. It can, for example, be carried out either by keeping the products in curing chambers, or by digging or by spraying with water or curing products.

The curing step 130 preferably lasts at most 48 hours, preferably at most 24 hours, more preferably less than 23 hours and it may be substantially equal to 20 hours. The curing step 130 generally lasts at least two hours, preferably at least six hours and more preferably at least 12 hours.

Preferably, within the framework of the invention, the curing step 130 is carried out in a hermetic mold. The hermetic mold advantageously makes it possible to limit or eliminate exchanges between the mixture and the outside air.

The curing step may or may not include heat treatment. However, even if heat treatment occurs, it is carried out at a temperature of less than 500°C, so the clay is still raw after curing and there is no elimination of bound water. In other words, the clay is not calcined and can still be considered as raw clay. The effectiveness of the pozzolanic reaction on the mechanical properties of concrete is not linked here to total dehydroxylation and amorphization of the clay, unlike what is observed when using metakaolin (Konan et al., Comparative study of dehydroxylation/amorphization in two kaolins of different crystallinity. J. Soc. Ouest-Afr. Chim.(2010) 030; 29-39). Furthermore, the reaction with the “activating” composition does not modify the structure of the raw clay which can still be identified in the final material by scanning electron microscopy for example.

In the context of the present invention, preferably, the heat treatment is carried out at a temperature above 25°C, preferably above 30°C. However, in order to respect a favorable energy balance, the curing step is carried out at a temperature below 120 ^° C, preferably below 100°C and more preferably below or equal to 80°C. For example, the heat curing step is carried out at a temperature between 20°C and 90°C, preferably the heat curing step is carried out at a temperature between 25°C and 80°C, even more preferably between 25°C and 65°C.

Furthermore, the heat treatment can be carried out over the entire curing step but also over a shorter period. Thus, preferably, the heat treatment is carried out over a period of less than or equal to 20 hours, more preferably less than 15 hours, and even more preferably less than 10 hours.

As illustrated in Figure 1, the method according to the invention may include a step 140 of demolding the prefabrication element. The demolding step 140 is generally known to those skilled in the art who will be able to implement it. This step is notably facilitated by the possible steps of preparing the molds, for example with the use of demolding agent and formwork oil, the use of shims for reinforcement, or the use of systems allowing hermetic covering of the parts.

Finally, the method according to the invention may include a drying step 150 of the prefabrication element. The drying step 150 is generally known to those skilled in the art who will be able to implement it. This step may take place under specific conditions, in particular sheltered from wind, frost and sun for example.

Within the framework of the various embodiments and characteristics of the present invention, the inventors have been able, for the first time, to obtain a prefabrication element or a construction material having a water buffer value greater than or equal to 0.75, preferably greater than or equal to 01, more preferably greater than or equal to 20 1.2.

Furthermore, certain prefabricated elements or a construction material are quick-setting, having a minimum compressive strength on cylinders, after 20 hours or less of curing step, as measured by standard NF EN 206-1 greater than or equal to 16 MPa, preferably greater than or equal to 18 MPa, more preferably greater than or equal to 20 MPa. Thus, the construction binder is in particular a quick-setting construction binder and likewise, the construction material according to the invention is a quick-setting construction material.

The methods according to the invention may incorporate the embodiments of the construction binder described above, whether or not they are advantageous, particular or preferred, in particular characteristics concerning the main constituents of the construction binder: the raw clay matrix, the deflocculating agent, the activation composition and the calcined metal oxide composition.

According to another aspect, the invention relates to a construction material comprising a construction binder according to the invention. In particular, the invention relates to a construction material formed from a construction binder according to the invention. The construction materials may for example be selected from: a mortar, a coating, a plaster, an insulator, a lightweight concrete, a prefabrication element.

The invention relates to a construction material obtained, or capable of being obtained, from a method according to the invention.

Advantageously, the construction binder according to the invention is used to form a construction material so that the fillers represent between 200% and 900% by weight of the construction binder. For example, in a construction material according to the invention, the construction binder according to the invention preferably represents between 10% and 33% by weight of the construction material.

In particular, a building material formed from the building binder according to the invention will comprise at least 5% by weight of raw clay from the smectite family. Preferably, the building material will comprise at least 8% by weight of raw clay from the smectite family and even more preferably at least 10% by weight of raw clay from the smectite family.

Advantageously, a building material formed from the building binder according to the invention will further comprise at least 5% by weight of at least one metal oxide corresponding to the oxide of a metal having at least two valence electrons. Preferably, the at least 5% by weight may be formed from several different metal oxides. These metal oxides may come from several sources. Preferably, the metal oxides formed with a metal having at least two valence electrons will be contained in the activation composition and/or in the calcined metal oxide composition. Preferably, the building material comprises at least 10% by weight of at least one metal oxide corresponding to the oxide of a metal having at least two valence electrons, more preferably at least 15% by weight; even more preferably at least 20% by weight.

The construction material according to the invention may comprise plant fibers, preferably hemp shiv.

The building material according to the invention may comprise diatom frustules.

The construction material according to the invention may have a water buffer value greater than or equal to 0.75; preferably greater than or equal to 1; more preferably greater than or equal to 1.2.

The construction material according to the invention may have a minimum compressive strength on cylinders at 1 day as measured by standard NF EN 206-1 greater than or equal to 2 MPa; preferably greater than or equal to 3 MPa, preferably greater than or equal to 5 MPa.

The construction material according to the invention may have a minimum compressive strength on cylinders at 7 days as measured by standard NF EN 206-1 greater than or equal to 5 MPa, preferably greater than or equal to 10 MPa.

Furthermore, the construction material according to the invention may have a minimum compressive strength on cylinders at 28 days as measured by standard NF EN 206-1 of less than or equal to 40 MPa, for example less than or equal to 30 MPa and preferably, as illustrated in the examples, less than or equal to 20 MPa. However, for certain applications, the minimum compressive strength on cylinders at 28 days may be much lower.

Preferably, the construction material according to the invention can have a minimum compressive strength on cylinders at 28 days as measured by standard NF EN 206-1 ranging from 10 to 30 MPa, preferably from 10 to 20 MPa.

The construction material according to the invention may be formed from a construction binder comprising excavated earth comprising the raw clay matrix.

The construction binder according to the invention can be used for the manufacture of:

Insulating construction material: binder according to the invention and lightweight aggregates of the “plant or porous” type;

- Mortar and concrete sprayed by dry or wet method,

Poured concrete/mortar,

- Compacted concrete/mortar,

Extruded concrete/mortar, • ¹

- Concrete foam,

- Lightweight concrete: the construction binder according to the invention may, for example, include straw, rice husk, hemp shiv, seaweed, wood chips, sunflower, sargassum, reed, wheat husks or other cereals and their mixtures;

Fiber-reinforced concrete: carbon fibers, glass, polypropylene, flax, hemp, yucca, jute, kenaf, Mauritanian ampelodesmos, coconut, oil palm, oil date palm, banana and pineapple..., 30 - High-temperature performance concrete,

- Liquid screed, Mortar,

- Construction systems or prefabrication elements: manufacture of concrete blocks or slabs in the factory from the binder according to the invention such as posts including silica fumes, earth concrete, a wood frame / earth concrete coupling, 35 earth mortar walls, reinforced earth concrete, and

Isolation modules.

The invention also relates to the use of the construction binder according to the invention, for the production of composite materials or prefabricated blocks.

Composite materials are, for example, prefabricated building panels such as 5-panel panels, while prefabricated blocks are, for example, door or window lintels, prefabricated wall elements, or any other prefabricated building element.

Thus, in particular, the invention relates to a prefabricated element capable of being formed from a construction binder according to the invention. Advantageously, this prefabricated element 10 will have been formed from a construction binder according to the invention.

Preferably, this prefabricated element, such as a partition, has a face with a surface area of at least 1 m ² , more preferably at least 1.5 m ² , even more preferably at least 2 m ² .

Furthermore, the prefabricated element may have a thickness of between 0.3 cm and 20 cm, advantageously between 0.5 cm and 10 cm and preferably between 1 cm and 7 cm. Such a prefabricated element advantageously has a water buffer value greater than or equal to 0.75, preferably greater than or equal to 1, more preferably greater than or equal to 1.2 and even more preferably greater than or equal to 1.5. This is particularly useful when the prefabricated element has a face with a surface area of at least 1 m ² , more preferably at least 1.5 m ² , even more preferably at least 2 m ² .

Furthermore, the invention is particularly suitable for such prefabricated elements when it comprises excavated clayey earth.

In particular, the construction binder according to the present invention is particularly suitable for a partition manufacturing process. Indeed, in order to be able to form building walls or partitions from prefabricated materials, it is necessary to have a strong construction material with a rapid setting time, i.e. with a compressive strength of at least 2 MPa after 24 hours and greater than 10 MPa after 28 days and which, once dry, has a MBV greater than 0.8, preferably greater than 1.2 and for example between 0.8 and 3.

Thus, the present invention relates to a use of a construction binder according to the present invention for the manufacture of partitions, preferably prefabricated partitions and even more preferably partitions having a compressive strength of at least 2

MPa after 24 hours and greater than 10 MPa after 28 days and which, once dry, has a MBV of between 0.8 and 3.

Such use may include the addition to the construction binder according to the invention of fillers such as: sand, plant fibers such as hemp shiv.

Advantageously, the construction binder according to the invention is used so that the fillers represent between 200% and 900% by weight of the construction binder. For example, in a partition according to the invention, the construction binder according to the invention preferably represents between 10% and 33% by weight of the construction material.

The invention also relates to a partition prepared from a construction binder according to the invention. Such a partition may include other bio-sourced materials. In particular, when a construction binder according to the present invention is used for the manufacture of an insulating construction material, it may comprise lightweight aggregates of plant origin.

We have presented in detail above a preferred embodiment of the invention.

However, the features of this embodiment, for example the advantageous, particular, preferred or non-preferred features, can be combined with other embodiments presented below.

Indeed, the present invention also relates to a construction binder comprising a raw clay matrix, a deflocculation agent and an activation composition, characterized in that it has a minimum resistance to compression on cylinders as measured by standard NF EN 206-1, at 28 days greater than or equal to 12 MPa, preferably greater than 15 MPa and a water buffer value greater than or equal to 0.7, preferably greater than or equal to 1, more preferably greater than or equal to 1.2 and even more preferably greater than or equal to 1.5. Advantageously, the construction binder will further comprise a calcined metal oxide composition. In particular, the present invention relates to a construction binder comprising a raw clay matrix, a deflocculation agent and an activating composition, the construction binder allowing the preparation of a construction material having a minimum compressive strength on cylinders as measured by standard NF EN 206-1, at 28 days greater than or equal to 12 MPa, preferably greater than 15 MPa and a water buffer value greater than or equal to 0.7, preferably greater than or equal to 1, more preferably greater than or equal to 1.2 and even more preferably greater than or equal to 1.5 measured at the earliest 10 days after manufacture and preferably 28 days. Advantageously, the construction binder will further comprise a calcined metal oxide composition.

The invention may also relate to a construction binder comprising a raw clay matrix, a deflocculation agent and an activating composition, the raw clay matrix comprising a mixture of at least two types of clays, preferably the clay matrix comprising at least smectite. More preferably, the two types of clays have a specific surface area at least equal to 30 m ² /g, preferably at least equal to 50 m ² /g, more preferably greater than 100 m ² /g.

Even more preferably, the invention relates to a construction binder comprising a raw clay matrix, a deflocculation agent, and an activating composition, characterized in that the raw clay matrix comprises a mixture of at least two types of clays, for example including smectite, and in that the binder further comprises a calcined metal oxide composition. Advantageously, the calcined metal oxide composition is a blast furnace slag. Preferably, the construction binder comprises at least 20% by weight of calcined metal oxide composition, more preferably at least 20% by weight of blast furnace slag.

• The invention also relates to a construction binder comprising a raw clay matrix, a deflocculation agent, an activating composition and a calcined metal oxide composition, characterized in that the deflocculation agent comprises a lignosulphonate, a polyacrylate, a humate or their mixture.

The invention also relates to a construction binder comprising a raw clay matrix, a deflocculation agent, an activating composition and a calcined metal oxide composition, characterized in that it comprises from 30% to 70% by weight, preferably from 40% to 60% by weight of raw clay matrix and in that it has:

a ratio (raw clay matrix) / (calcined metal oxide composition), less than 6, preferably less than 4, preferably between 1 and 3; and a ratio (calcined metal oxide composition) / (deflocculating agent) greater than 12; and preferably the calcined metal oxide composition being a slag from metallurgy, such as a blast furnace slag.

The invention also relates to a construction binder comprising a raw clay matrix, a deflocculation agent, an activating composition and a calcined metal oxide composition, characterized in that it comprises:

30' - from 30% to 70% by weight, preferably from 40% to 60% by weight of raw clay matrix;

from 15% to 45% by weight, preferably from 20% to 40% by weight of the calcined metal oxide composition;

and preferably, the raw clay matrix comprises at least two types of clays.

As illustrated by the examples below, the present invention provides a solution based on a mixture of raw clay matrix, deflocculating agent and activating composition to provide a construction binder with mechanical properties similar to the standard while having a reduced carbon footprint.

EXAMPLES:

Preparation of a construction binder:

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, a deflocculating agent and the activation composition in predetermined quantities, then water is added and the solution is mixed at low speed, i.e. substantially at sixty revolutions per minute for thirty seconds. Then, sand is added to the premix and the whole is mixed at higher speed, i.e. at approximately 120 revolutions per minute for one minute.

The mass ratio of water to dry matter in the composition (also called construction binder) is adjusted to a value between 0.4 and 0.6.

In a particular example, the construction material, a mortar, comprises 25% by weight of binder, 75% by weight of sand; this mixture being supplemented with water for a mass ratio of water to dry matter of the binder adjusted to a value of 0.5.

The mortar based on the construction binder thus formed is then poured into a mold and left to mature at room temperature, i.e. approximately 20 degrees Celsius for twenty-eight days.

Alternatively, the mortar may be poured into a mold and then left to mature for at least twenty-four hours in a curing stage, at room temperature, i.e. approximately 25 degrees Celsius or preferably under heat treatment. During this curing stage, the mold may be sealed or the top layer of the building material may be covered with a curing compound to limit/prevent evaporation.

30*

Methodology for measuring the mechanical properties of construction binders:

Once maturation is complete, the mechanical strength is measured. The mechanical strength of a construction binder is its compressive strength, such compression being measured according to standard NF EN 196-1, for a prism of 40 millimeters 35 on each side and 160 millimeters in length and is expressed in Mega Pascal (MPa).

Methodology for measuring MBV values:

oii

The water buffer value can be measured by any method known to the person skilled in the art. For example, the person skilled in the art may refer to the method described in “Durability and hygroscopic behavior of biopolymer stabilized earthen construction materials” Construction and Building Materials 259 (2020). The samples are placed in a climatic chamber at 23°C and 33% relative humidity and left until they reach a constant mass (e.g., a climatic chamber model MHE 612). All samples equilibrate after 15 days of storage under these conditions. The samples are then exposed to high humidity cycles (75% RH for 8 hours) followed by a low relative humidity cycle (33% RH for 16 hours). The samples are weighed at regular intervals with a laboratory balance accurate to 0.01 g. After two stable cycles, the samples are removed from the climatic chamber.

MBV =

Am S x A%RH where Am is the change in sample mass due to change in relative humidity, S is the total exposure area and Δ%RH is the difference between the humidity levels.

Comparison of the construction binders according to the invention with known construction binders:

Table 2 below shows, 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]

CEM1 Binder (Reference) MUP1 MUP0 MUP-Y1 MUP-Y0 MUP-Y2 Raw Clay Matrix 0.0% 20% Smectite 10% Smectite / 10% Kaolinite 40% Smectite 39% Kaolinite 41% Smectite/Kaolinite 50/50 Deflocculating Agent 0.0% 1.0% 1.0% 1.5% 2% 1.5% Activation composition 0.0% 18.0% 18.0% 23.5% 23% 23.5% Metakaolin 0.0% 0.0% 0.0% 0% 0% 0% CEM1 Cement 100.0% 0.0% 0.0% 0% 0% 0% Composition of metal oxides 0.0% 62.0% 62.0% 35% 36% 34%

Compressive strength (MPa) at 28 days 45 39 45 14 19 17 MBV 0.41 0.88 0.72 1.4 0.69 1.3 Estimated Carbon Footprint Strong Weak Weak Weak Weak Weak

Thus, Table 2 presents the mechanical resistance of a known construction binder (CEM1 binder) and not forming part of the invention, such as the CEM1 type construction binder better known under the name of “Portland” cement whose compressive strength 5 is of the order of 45 MPa. It also presents the calculated water buffer values (MBV = 0.41) for these construction materials of the prior art.

Table 2 also shows a MUP1 formulation according to the invention. It is important to note that this formulation comprising 1% deflocculating agent, although comprising a low proportion of raw clay matrix (20%), has a mechanical resistance 10 identical to the mechanical resistance of Portland cement but much superior hygrometric properties (MBV = 0.88).

Furthermore, while MUP1 comprising 20 wt% Smectite has an MBV greater than 0.75 (0.88), MUP0 comprising 10 wt% smectite and 10 wt% kaolinite, has an MBV less than the limit of 0.75.

Similarly, MLJP-YO containing approximately 40% kaolinite does not allow an MBV value greater than or equal to 0.75 to be reached, whereas MUP-Y1 containing approximately 40% smectite allows an MBV value of 1.4 to be reached.

Thus, clays from the smectite family are very advantageous for the preparation of 20 construction materials with water buffer capacities capable of improving the comfort of residents through thermal and water regulation.

Table 2 also shows that a clay mixture (MLIP-Y2) such as a 50/50 mixture of Smectite and Kaolinite can significantly improve water buffering capacities (MBV 25 = 1.3) while exhibiting high compressive strength.

On the ineffectiveness of adding raw clay to a CEM1:

Table 3 below shows a known formulation of CEM1-X1 Cement to which a deflocculating agent has been added and five cement formulations to which CEM1-X2, CEM1-X3, CEM1-X4 and CEM1-X5 clay have been added, in different proportions.

[Table 3]

CEM1-X1 CEM1-X2 CEM1-X3 CEM1-X4 CEM1-X5 Raw Clay Matrix 0% 20% 40% 60% 80% Deflocculating Agent 3% 3% 3% 3% 3% Activation composition 0% 0% 0% 0% 0% CEM1 Cement 97% 77% 57% 37% 17% Compressive Strength (MPa) 77 61 42 24 8 MBV 0.41 0.29 0.53 0.59 0.53

The CEM1-X1 achieves very high mechanical resistance but has insufficient MBV (<0.75).

The addition of 20% raw clay surprisingly induces a reduction in the hygrometric properties of the construction material as well as a reduction in mechanical resistance, even in the presence of a deflocculating agent.

It can be seen that from 40% raw clay (CEM1-X3) in combination with CEM1 cement and a deflocculating agent, the MBV increases compared to CEM1-X1 but still remains insufficient (<0.75). In addition, the mechanical properties of the construction material CEM1-X5 are strongly affected until reaching insufficient levels (<10).

Thus, a combination of raw clay, CEM1 and deflocculating agent does not allow the production of a binder capable of exhibiting both satisfactory MBV and mechanical resistance properties.

Importance of blast furnace slag:

Table 4 below shows a reference formulation MUPZO, a formulation according to the invention MUPZ1 and a formulation according to the invention MUPZ2.

[Table 4]

MUPZO MUPZ1 MUPZ2 Raw Clay Matrix 57% Smectite 59% Smectite 43.5% Smectite Deflocculating Agent 3% 1% 1.5% Activation composition 0% 20% 20% Calcined metal oxide composition: Blast furnace slag 0% 20% 35% CEM1 Cement 40% 0% 0% Compressive Strength (MPa) 28 12 26 MBV 0.59 1.35 1.9

Table 2 shows that replacing Portland cement with an activation composition and a calcined metal oxide composition (e.g. blast furnace slag or ash type) allows for compositions MUPZ1 and MUPZ2 to achieve

MBV well above 0.75.

Furthermore, the MUPZ2 composition, which includes an organic deflocculant, exhibits an MBV almost equal to 2 while exhibiting a compressive strength greater than 25 MPa.

Claims (26)

1. Construction binder comprising a raw clay matrix, a deflocculation agent and an alkaline activation composition, characterized in that: it comprises from 2% to 40% by dry weight of the alkaline activation composition; it comprises at least 40% by weight of the raw clay matrix and the raw clay matrix comprises at least one raw clay of the smectite family; the at least one raw clay of the smectite family represents at least 20% by weight of the construction binder; and the construction binder comprises less than 15% by weight of Portland cement. 2. Construction binder according to claim 1 characterized in that the raw clay matrix comprises a mixture of at least two types of clay. 3. Construction binder according to claims 1 or 2, characterized in that the raw clay matrix comprises at least one clay having a specific surface area at least equal to 100 m ² /g as measured according to standard NFP 94-068. 4. Construction binder according to any one of claims 1 to 3, characterized in that it further comprises a calcined metal oxide composition. 5. Construction binder according to the preceding claim, characterized in that the construction binder comprises at least 20% by weight of the calcined metal oxide composition. 6. Construction binder according to one of claims 4 or 5, characterized in that it has a mass ratio of the raw clay matrix to the calcined metal oxide composition greater than or equal to 1. 7. Construction binder according to any one of claims 1 to 6, characterized in that the activation composition comprises at least 40% by weight of at least one metal oxide corresponding to the oxide of a metal having at least two valence electrons. 8. Construction binder according to one of claims 1 to 7, characterized in that the deflocculation agent is an organic compound. 9. Construction binder according to any one of claims 1 to 8, characterized in that it comprises excavated earth comprising the raw clay matrix. 10. Construction material capable of being formed from a construction binder 5 according to any one of claims 1 to 9, comprising: at least 2% by weight of at least one raw clay from the smectite family, less than 3.75% by weight of Portland cement, and having a water buffer value measured at the earliest 10 days after manufacture greater than or equal to 0.75; preferably greater than or equal to 1, said water buffer value being measured according to the measurement methodology of * MBV values as described in the description. 11. Building material according to claim 10, characterized in that it comprises at least two raw clays. 12. Construction material according to one of claims 10 or 11, characterized in that it comprises at least 2% by weight of a calcined metal oxide composition. 13. Construction material according to any one of claims 10 to 12, 20 characterized in that it comprises at least 5% by weight of at least one metal oxide corresponding to the oxide of a metal having at least two valence electrons. 14. Construction material according to any one of claims 10 to 13, characterized in that it has a minimum compressive strength on 25 cylinders at 1 day as measured by standard NF EN 206-1 greater than or equal to 2 MPa. 15. Prefabricated element capable of being formed from a construction binder according to any one of claims 1 to 9, said prefabricated element: having a face with a surface area of at least 1 ^m2 and a thickness of between 30 and 0.3 cm and 20 cm; comprising at least 5% by weight of at least one raw clay from the smectite family, comprising less than 3.75% by weight of Portland cement and having a water buffer value, measured at the earliest 10 days after manufacture, greater than or equal to 0.75, said water buffer value being measured according to the MBV value measurement methodology as described in the description. 16. Prefabricated element according to the preceding claim, characterized in that it comprises at least 2% by weight of a calcined metal oxide composition. 5 17. Method (100) for producing a prefabrication element prepared from a construction binder, said construction binder comprising a raw clay matrix, an alkaline activation composition and a deflocculation agent, said method (100) comprising: - Provide (110) a construction binder comprising a raw clay matrix 10 comprising at least one raw clay from the smectite family, a deflocculation agent and an alkaline activation composition; the construction binder comprising from 2% to 40% by dry weight of the alkaline activation composition; at least one raw clay from the smectite family represents at least 20% by weight of the construction binder; and the construction binder comprising less than 15 15% by weight of Portland cement, Mix (120) the construction binder with aggregates and water, and Carrying out a curing step (130) of the mixture, said curing step (130) comprising a heat treatment of the mixture, preferably at a temperature less than or equal to 100°C, for a duration of between 2 hours and 23 hours. ' ' 20 18. Method (100) for producing a prefabrication element according to claim 17, characterized in that the raw clay matrix comprises a mixture of at least two types of clay. 19. Method (100) for producing a prefabrication element according to claim 17 or 18, characterized in that the raw clay matrix comprises at least one clay 25 having a specific surface area at least equal to 100 m ² /g. " 20. Method (100) for producing a prefabrication element according to any one of claims 17 to 19, characterized in that the construction binder comprises at least 40% by weight of raw clay matrix. i j 21. Method (100) for producing a prefabrication element according to any one 30 of claims 17 to 20, characterized in that the construction binder further comprises a calcined metal oxide composition. 22. Method (100) for producing a prefabrication element according to the preceding claim, characterized in that the construction binder comprises at least 20% by weight of the calcined metal oxide composition. L_____________i 23. Method (100) for producing a prefabrication element according to one of claims 21 or 22, characterized in that the construction binder has a mass ratio of the raw clay matrix to the calcined metal oxide composition greater than or equal to 1. 5 24. Method (100) for producing a prefabrication element according to any one of claims 17 to 23, characterized in that the construction binder comprises at most 25% by dry weight of the alkaline activation composition. 25. Method (100) for producing a prefabrication element according to any one of claims 17 to 24, characterized in that the deflocculation agent is an organic compound. 26. Method (100) for producing a prefabrication element according to any one of claims 17 to 25, characterized in that the deflocculation agent represents at most 2% by weight of the construction binder.