Compressed Earth Brick and Manufacturing Process

Abstract

The invention relates to a method for manufacturing (200) a compressed earth brick (51) comprising a step of forming (230) a binder comprising a raw clay matrix (2) and an activation composition; a step of mixing (240) the binder with at least two raw earths (4) having respectively different particle size profiles, preferably at least one of the two raw earths (4) being crushed raw earth (4); a step of shaping (250) a compressed earth brick (51) from the mixture. Furthermore, the present invention provides a system (1) for manufacturing a compressed earth brick (51) comprising a first particle size distribution modification device arranged to receive raw earth (4); a second particle size distribution modification device arranged to receive a portion of the raw earth (4); a mixing element (50). Figure to be published with the abbreviation: Figure 2

Description

Title of the invention: COMPRESSED EARTH BRICK AND MANUFACTURING METHOD Technical field

[0001] The invention relates to the field of construction and more particularly to that of masonry elements which can be used in construction. In particular, it relates to a method for manufacturing a compressed earth brick. Furthermore, the invention relates to the compressed earth brick according to the invention and a suitable manufacturing system. Prior art

[0002] Raw earth is a material that has been used for several millennia and is now used in more than 150 countries. A material that is abundantly available and easily accessible throughout the planet, its use in the form of compressed earth bricks can be very beneficial from an environmental point of view.

[0003] Nevertheless, in the most developed countries, concrete, despite its significant environmental footprint, remains predominant compared to compressed earth bricks.

[0004] Compressed earth brick (CEB) is, as its name suggests, a compressed earth brick. The earth in this brick is generally composed of gravel, sand, clay and silt. CEBs have many advantages. In the context of interior design, a CEB wall has cooling properties and helps prevent the development of mold. CEB also has interesting acoustic properties: it allows for sound reverberation and thus creates a quiet room. This advantage is already used for the construction of music rooms or large rooms requiring good acoustics. Finally, a CEB partition can attenuate electromagnetic fields and provides thermal inertia due to high thermal conductivity.

[0005] BTCs may or may not be fired. Fired BTCs generally have higher mechanical strength but a lower carbon footprint. Indeed, CO2 is emitted during the brick firing process. Thus, unfired bricks are now preferred because they require less energy than fired bricks (CO2 emissions into the atmosphere are 80% lower than those of fired bricks).

[0006] However, most raw or unfired BTCs have degraded mechanical resistance compared to fired BTCs. To overcome this, BTCs are stabilized with a hydraulic binder, generally Portland cement. Cement Portland cement is composed mainly of clinker, which results from the calcination of a mixture of 80% limestone and 20% clay, heated to a temperature of approximately 1450°C. The content of this hydraulic binder is generally between 5 and 20% by mass, depending on technical requirements. For comparison, Portland cement represents on average 15% by mass of concrete.

[0007] Hydraulic binders inherently have an impact on the environment due to their highly energy-intensive production and also the release of CO2 during manufacturing. In recent decades, significant research has been devoted to the development of stabilized BCCs with reduced Portland cement contents as a more affordable and environmentally friendly alternative to other, more common building elements.

[0008] In particular, it has been shown (Kumar et al 2022, Effects of sugarcane bagasse fibers on the properties of compressed and stabilized earth blocks. Construction and Building Materials 315 (2022) 125552) that the inclusion of 0.5% to 1.0% by weight of plant fibers in BTCs stabilized at 12% by weight of cement can significantly improve the mechanical properties of the stabilized BTCs without compromising their durability properties. However, the cement content here is almost equal to the cement content in conventional concretes (12% vs. about 15%).

[0009] It has been proposed to combine raw earth with plastic waste (Akinwumi et al 2019. Marine plastic pollution and affordable housing challenge: Shredded waste plastic stabilized soil for producing compressed earth bricks. Case Studies in Construction Materials 11 (2019) e00241). However, these BTCs, made with a mixture of earth and varying percentages (0, 1, 3 and 7%) of crushed plastic waste, presented values ​​of resistance to comprehension well below 4 MPa.

[0010] It has been shown that the mechanical strength of BTC can be improved by replacing part of the Portland cement with lime. This is particularly true when using earth with reduced clay and silt contents (Malkanthi et al 2020. Lime stabilization for compressed stabilized earth blocks with reduced clay and silt. Case Studies in Construction Materials 12 (2020) e00326). The authors have in particular shown that mechanical strengths greater than or equal to 4 MPa can be achieved from 5% Portland cement combined with 5% lime, by dry weight relative to the mixture for BTC. However, the use of lime to replace part of the Portland cement has often been reported as extending drying times. Furthermore, at contents of less than 5% Portland cement in the mixture with raw earth, the mechanical strengths are disappointing.

[0011] BTCs have been considered a key masonry unit during the recent decades. Many studies have shown that compressive strength decreases with increasing clay and silt content. The majority of researchers are interested in clay and silt content in raw earth up to 15%. A study to determine the influence of clay and silt content in raw earth showed that for fines contents of 15% or more, more than 8% cement is required to achieve a mechanical strength of 4 MPa or more, while for raw earth with 10% or less fines, more than 6% Portland cement is required (Malkanthi et al 2021. Use of construction waste to modify soil grading for compressed stabilized earth blocks (CSEB) production. Case Studies in Construction Materials 15 (2021) e00717). Therefore, when using high clay and silt content, only high cement percentages can achieve the minimum strength requirements.

[0012] It has been proposed to use a clinker composition in combination with Portland cement and lime to form compressed earth bricks. However, simultaneous mixtures of these components have generally made it possible to achieve strengths lower than the value (4 MPa) recommended by CRATerre for compressed earth bricks (Lawane el al 2019. Mechanical and physical properties of stabilized compressed coal bottom ash blocks with inclusion of lateritic soils in Niger. Scientific African. Volume 6, November 2019, e00198). In addition, it has been confirmed that in the presence of clinker, the substitution of Portland cement with lime leads to a degradation of performance. Finally, the bricks produced with 8.5% cement, 17.1% lateritic soils and the clinker supplement reached the target strength after 90 days of curing.It has also been proposed to stabilize raw earth from blast furnace slag in combination with lime or Portland cement (Oti et al 2009). Compressed earth bricks with acceptable mechanical resistance have been obtained but this after very long drying times (e.g. more than 40 days).

[0013] Thus, plastics, plant fibers, clinker, blast furnace slag, lime, etc. have been proposed to replace at least part of Portland cement in BTCs. However, the BTCs obtained either had compressive strengths lower than 4MPa or required curing times that were far too long.

[0014] Thus, there is a need for new solutions to further reduce the carbon footprint of high strength BTC formation while increasing production speed. Summary of the invention

[0015] The invention aims to overcome these drawbacks. The following presents a simplified summary of selected aspects, embodiments and examples of the present invention for the purpose of providing a basic understanding of the invention. However, the summary of the invention does not constitute an exhaustive overview of all aspects, embodiments and examples of the invention. The sole purpose of the summary is to present selected aspects, embodiments and examples of the invention in a concise form as an introduction to the more detailed description of the aspects, embodiments and examples of the invention which follow the summary.

[0016] The invention relates in particular to a method for manufacturing a compressed earth brick, said method comprising the following steps: - Formation of a binder comprising: • a raw clay matrix, and • an activation composition; - Mixing the binder with at least two raw earths having respectively different granulometric profiles, preferably at least one of the two raw earths being a crushed raw earth; and - Shaping a compressed earth brick from the mixture.

[0017] The applicant has developed a new process for manufacturing compressed earth bricks that makes it possible to obtain bricks with a very low carbon footprint, high mechanical strength and a reduced curing time. Conventionally, the preparation of compressed earth bricks requires the use of Portland cement or clinker at contents greater than 5%. With the present solution, the transport of material across the territory and the overall environmental footprint are significantly reduced thanks in particular to a two-step mixing process (i.e. formation of a binder then mixing of the binder and the raw earth) and the use of specific combinations of constituents.Furthermore, while raw clay concentrations of less than 15% were recommended when stabilizing compressed earth bricks with Portland cement, the inventors developed a solution to combine raw clay and Portland cement for fast-drying bricks with mechanical strengths meeting CRATerre criteria.

[0018] According to other optional features of the manufacturing method according to the invention, it may optionally include one or more of the following features, alone or in combination: - at least one of the two raw earths used during the mixing step is an unground raw earth. During the grinding step, preferably two ground raw earths are used. - at least one of the two raw earths is a crushed raw earth and the crushed raw earth used during the mixing step the crushed raw earth used during the mixing step has a D50 of less than 500 pm, the D50 being preferably measured according to ASTM D6913-04(2009). Optionally, D50 can be measured according to the ASTM standard D6913-04(2009) coupled with the indications of the ISO 13320:2020 standard, for example for fine particles (eg <65 pm). at least one of the raw earths used in the mixing step has a D50 greater than 500 pm, the D50 preferably being measured according to ASTM D6913-04(2009). the activating composition is an alkaline composition comprising one or more compounds having a pKa greater than or equal to 10. during the mixing stage, the mixture comprises 5% or less by dry weight of cement, in particular Portland cement. during the binder formation stage, the mass proportion by dry weight of raw clay matrix in the binder is at least 30% by dry weight. during the binder formation step, the added raw clay matrix has a D50 of less than 400 pm, the D50 preferably being measured according to ASTM D6913-04(2009). Preferably, the added raw clay matrix has a D50 of less than 200 pm, the D50 preferably being measured according to ASTM D6913-04(2009) in combination with ISO 13320:2020. during the binder formation step, the mass proportion by dry weight of activation composition in the binder is at most 40%. the binder formation step further comprises the addition of a calcined metal oxide composition, preferably the dry weight mass proportion of calcined metal oxide composition in the binder is at most 40%. the binder formation step further comprises the addition of a deflocculant, preferably the mass proportion by dry weight of deflocculant in the binder is at least 0.01%. during the binder formation step, the mass proportion by dry weight of raw clay in the binder is at least 5% by dry weight. Preferably, the mass proportion by dry weight of raw clay in the binder is at least 10% by dry weight, more preferably at least 12% by dry weight, even more preferably at least 14% by dry weight. during the stage of mixing the binder with the raw earth, the binder represents at least 3% by dry weight of the mixture. it comprises a step of carrying out a cure of the compressed earth brick. Preferably, the cure may be a cure in a humid atmosphere, for example at a relative humidity of 95% or more, preferably 98% or more. The treatment can be carried out for at least two days, preferably at least four days. - the treatment is carried out over a period of at most 15 days, preferably at most 10 days. - the curing is carried out in such a way as to obtain a compressed earth brick with a compressive strength greater than or equal to 4 MPa, according to standard NF EN 771-3+A1 / CN. For example, the process may include a step of measuring the compressive strength as a function of the curing time in order to determine the duration of the curing to be carried out. - it comprises a step of acquiring a value of at least one granulometric property of the raw clay matrix and the raw earths and in that the step of mixing the binder with the raw earths comprises an addition of calculated quantities of raw earths, the calculated quantities of raw earths being calculated by one or more processors according to the values ​​of at least one granulometric property previously acquired.

[0019] According to another object, the invention further relates to a compressed earth brick capable of being manufactured by the manufacturing method according to the invention. In particular, the invention further relates to a compressed earth brick directly manufactured by the manufacturing method according to the invention.

[0020] According to other optional characteristics, the compressed brick according to the invention may optionally include one or more of the following characteristics, alone or in combination: - it contains at least 5% by dry weight of raw clay and between 0.5 and 4% by dry weight of cement, preferably Portland cement. - it also contains a deflocculation agent. - it also contains at least 2% by dry weight of metal oxides, preferably at least 5% by dry weight of metal oxides.

[0021] According to another object, the invention further relates to a system for manufacturing a compressed earth brick comprising: - A first particle size distribution modification device arranged to receive raw earth having a first particle size distribution profile and to treat it so that the treated raw earth has a second particle size distribution profile; for example the first particle size distribution modification device being a crumbler, grinder, crumbler, or a granulator; - A second particle size distribution modifying device arranged to receive a portion of the raw earth having the second particle size distribution profile, preferably only a portion of the raw earth having the second particle size distribution profile, and to treat it so that the treated raw earth has a third particle size distribution profile; for example, the second particle size distribution modifying device being a hammer mill, ball mill or rod mill; and - A mixing member, in particular a mixer, configured to mix the raw earths having the second and third particle size distribution profiles with a binder comprising a raw clay matrix and an activating composition.

[0022] Such a manufacturing system makes it possible to take advantage of the combination of raw earths having different granulometric profiles. In the field of construction it is obviously known to prepare aggregates to form construction materials. The invention relates here to a manufacturing system arranged to prepare raw earths having different granulometric profiles in particular and making it possible to mix these different raw earths with a binder comprising a raw clay matrix and an activation composition.

[0023] According to other optional features of the system for manufacturing a compressed earth brick according to the invention, it may optionally include one or more of the following features, alone or in combination: - it further comprises one or more conveyors configured to convey the raw earth having the second particle size distribution profile and the raw earth having the third particle size distribution profile, to the mixing member. - the one or more conveyors comprise a bypass path positioned after the first particle size distribution modification device and configured to send, directly or indirectly (e.g. storage area), a portion of the raw earth having the second particle size distribution profile to the mixing member and another portion of the raw earth having the second particle size distribution profile to the second particle size distribution modification device. - it further comprises a third particle size distribution modification device arranged to receive a portion of the raw earth having the third particle size distribution profile and to treat it so that the treated raw earth has a fourth particle size distribution profile; the one or more conveyors being configured to transport the raw earth having the fourth particle size distribution profile to a mixing member configured to mix the earth raw material with the fourth particle size distribution profile with an activating composition. This allows the system to operate autonomously in supplying a large portion of the material used to form the BTC. In addition, this implies that the mixer is also configured to prepare the binder. the second particle size distribution modification device is further arranged to receive a portion of the raw earth having the second particle size distribution profile or the raw earth having the third particle size distribution profile and to process it so that the processed raw earth has a fourth particle size distribution profile; the one or more conveyors being configured to convey the raw earth having the fourth particle size distribution profile to a mixing member configured to mix the raw earth having the fourth particle size distribution profile with an activating composition. This allows the system to operate autonomously in providing a large portion of the material used to form the BTC without requiring three different particle size distribution modification devices.Additionally, this implies that the mixer is also configured to prepare the binder. it comprises means for measuring characteristics of the raw earths, in particular raw earths having the second and third particle size distribution profiles and in that the one or more conveyors are configured to convey the raw earth having the second particle size distribution profile and the raw earth having a third particle size distribution profile to the mixing member according to values ​​of characteristics of the raw earths. This makes it possible to improve the performance of the produced BTCs. The characteristics of the raw earths may for example refer to the particle size profile, in particular D10, D50 and / or D90. the first particle size distribution modification device is configured such that the treated raw earth has a D50 greater than 500 pm, preferably greater than or equal to 750 pm, more preferably greater than or equal to 1 mm, even more preferably greater than or equal to 1.5 mm, preferably the D50 being measured according to the indications of the standard ASTM D6913-04(2009). the second particle size distribution modification device is configured such that the treated raw earth has a D50 of less than 500 pm, preferably a D50 of less than 200 pm, preferably less than or equal to 150 pm, more preferably less than or equal to 100 pm, even more preferably less than or equal to 80 pm, preferably the D50 being measured according to the indications of the standard ASTM D6913-04(2009) in combination with the standard ISO 13320:2020. - the third particle size distribution modification device is configured so that the treated raw earth has a D50 less than or equal to 100 pm, preferably less than or equal to 50 pm, more preferably less than or equal to 40 pm, even more preferably a D50 less than or equal to 30 pm, preferably the D50 being measured according to the indications of the ASTM D6913-04(2009) standard in combination with the ISO 13320:2020 standard. In particular, the treated raw earth from the third particle size distribution modification device has a D50 lower than the D50 of the treated raw earth from the second particle size distribution modification device. Brief description of the drawings

[0024] Other characteristics and advantages of the invention will be better understood on reading the description which follows and with reference to the appended drawings, given for illustrative purposes and in no way limiting.

[0025] [Fig.l] represents a schematic illustration of a manufacturing method according to an embodiment of the present invention. The steps outlined in dotted lines are optional.

[0026] [Fig.2] represents a schematic illustration of a shaping step of compressed earth brick according to one embodiment of the present invention.

[0027] [Fig.3] represents a schematic illustration of a granular distribution of two fractions of raw earth, one being coarsely ground (A) and the other finely ground (B) and a mixture of raw earth (C).

[0028] [Fig.4] represents a schematic illustration of a brick manufacturing system of compressed earth according to one embodiment of the present invention.

[0029] The figures do not necessarily respect the scales, in particular in thickness, and this is for illustration purposes.

[0030] Aspects of the present invention are described with reference to flowcharts and / or functional diagrams of methods, apparatuses (systems) and computer program products according to embodiments of the invention.

[0031] In the figures, flowcharts and block diagrams illustrate the architecture, functionality and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowcharts or block diagrams may represent a system, device, module, or code, which includes one or more executable instructions for implementing the specified logical function(s). In some implementations, the functions associated with the blocks may appear in a different order than shown in the figures. For example, two blocks shown in succession may, in fact, be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order, depending on the functionality involved. Each block of the block diagrams and / or flowchart, and combinations of blocks in the block diagrams and / or flowchart, may be implemented by special hardware systems that perform the specified functions or acts or carry out combinations of special hardware and computer instructions. Description of the embodiments

[0032] Below, we describe a summary of the invention and the associated vocabulary, before presenting the disadvantages of the prior art, and finally showing in more detail how the invention overcomes them.

[0033] In the remainder of the description, the expression “compressed earth brick” or the term BTC may correspond to a construction material manufactured from a mixture comprising a binder and raw earth. The mixture will have undergone a compression step aimed at shaping it. Preferably, the BTC will not have undergone a combustion step.

[0034] In the remainder of the description, the expression "raw earth" may correspond to a granular mineral material, for example, derived from sedimentary rock or sedimentary deposits. Raw earth has different names depending on its composition or its origins. Raw earth may, for example, correspond to clayey, sandy clay, clayey-loamy, clayey-loamy, fine clayey-loamy, sandy-loamy, loamy, fine clayey-loamy, fine loamy, very fine loamy, sandy-loamy, sandy-loamy, and sandy soils. Raw earth may also correspond to waste rock (from discovery or production), exposed clays, excavated earth, such as excavated clayey earth, clayey sands from treatment plants, sludge or even sediments.

[0035] The term "binder" or "binder for compressed earth brick" within the meaning of the invention can be understood as a formulation making it possible to ensure the agglomeration of materials between them, in particular during the setting and then hardening of a construction material. Thus, it makes it possible in particular to ensure the agglomeration of sand and other constituents of the raw earth 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 on contact with water.

[0036] The expression "clay matrix", within the meaning of the invention, may correspond to one or more rock materials based on hydrated silicates 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, or mixtures thereof. In addition, a clay matrix may comprise silts.

[0037] For the purposes of the invention, the expression “raw clay matrix” may correspond to a clay matrix that has not undergone a calcination step. For example, this corresponds to a clay matrix 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 clay matrix may undergo a drying step by heating requiring a temperature rise generally substantially equal to or less than 150°C but no calcination step. A raw clay matrix may preferably comprise a mixture of rock materials that may, for example, comprise kaolinite, illite, smectite, micas such as muscovite, bentonite, chlorite, vermiculite, or mixtures thereof, as well as silts.

[0038] For the purposes of the invention, a “deflocculating agent”, “deflocculant” or “deflocculation agent” may correspond to a compound capable of dissociating aggregates and colloids, particularly in aqueous suspension. 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.

[0039] 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 composition. of metal oxides may comprise chemical species which are not metal oxides. For example, the composition of metal oxides 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. The person skilled in the art may, for example, use X-ray fluorescence, in particular according to the indications of standards NF EN 196-2 and NF EN 15309.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 preferably 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 which 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.

[0040] The term "Portland cement" refers to a hydraulic binder composed mainly of hydraulic calcium silicates, the setting and hardening of which 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 (CaSO4 • 2 H2O) or various traces of metals. For example, Portland cement may refer to CEMI.

[0041] The term "clinker" can refer to a constituent of cement and comes from the firing of a mixture composed of approximately 80% limestone and 20% aluminosilicates (such as clays). This firing, clinkerization, is generally carried out at a temperature of more than 1200°C, which is particularly energy-intensive and generates high greenhouse gas emissions. The clinker is generally ground and can then be mixed with blast furnace slag to produce composite cements.

[0042] The expression “excavated clayey earth” corresponds, in the sense of the invention, to an earth clayey soil obtained following a step where the soil has been dug, for example during excavation and / or earthwork operations, with a view to building, constructing or backfilling. In particular, within the meaning of the invention, the excavated clayey soil may or may not be moved outside the excavation site. Preferably and according to an advantage of the invention, the excavated soil is used on the excavation site or at a distance of less than 500 km, preferably less than 200 km, more preferably less than 50 km. Thus, the method according to the invention may comprise a step of removing raw soil and transporting raw soil over a distance of less than 500 km before its use in the method. Furthermore, advantageously, the clayey soil excavated within the scope of the invention is raw excavated clayey soil, i.e. 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 soil that has not undergone a temperature increase greater than 300°C, preferably greater than 200°C and more preferably a temperature greater than 150°C. Indeed, the raw clayey soil may undergo a drying step requiring a temperature increase 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 several seconds. An excavated clayey soil may have different particle size profiles. In the context of the invention, an excavated clayey soil may comprise particles of a size greater than 2 μm, preferably greater than 20 μm, preferably greater than 50 μm and for example greater than 75 μm as determined according to standard ASTM D422-63 or standard ASTM D6913-04(2009).Preferably, the excavated clay soil does not contain any aggregate larger than 2 cm as determined according to standard NF EN 933-1, preferably no aggregate larger than 0.5 cm.

[0043] The term "sand" can refer to particles, originating from the disintegration of rocks, whose size is between 0.063 mm and 2 mm.

[0044] The term "silt" can refer to particles whose grain size is intermediate between clays and sands (between approximately 2 and 50 micrometers).

[0045] The term "D50" corresponds to the median diameter for which 50% (by volume or mass, preferably by mass) of the grains, particles, aggregates or sediments have a size smaller than a given diameter. For example, a sieving and sedimentometry analysis method indicates a D50 = 5.8 mm, then 50% of the particles in the sample (by volume or mass, preferably by mass) are greater than 5.8 mm. D50 is generally used to represent the particle size of a group of particles. D50 is preferably measured according to ASTM D422-63 or ASTM D6913-04(2009) or in particular for fine particles ISO 13320:2020 (eg D10 or <65 pm). The expressions "granular property" "nullometric" or "granulometric profile" or "particle size distribution" may correspond to values ​​of parameters relating to the particle size distribution, for example in the raw clay matrix or in raw earths. There are many parameters relating to the particle size distribution such as D50, D10, D90.

[0046] In the remainder of the description, the term "% by weight" in relation to the binder, the mixture, or in relation to the compressed earth brick, must be understood as being a proportion relative to the dry weight. The dry weight corresponds to the weight before the addition of water, for example, necessary for the formation of the compressed earth brick. When the values ​​of % by weight are given in the form of intervals, the limits are included.

[0047] The expression "moisture buffer value" or "MBV" represents the capacity of a material to exchange moisture with its environment. It makes it possible to estimate the dynamic hygrothermal behavior of the material in question and is used to determine thermal comfort in the field of construction and more particularly the regulation of the interior humidity of a room or a building. For example, in the case of a compressed earth brick, the MBV will be relative to the compressed earth brick as a whole. The MBV is expressed in g / m2.%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 moisture 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 (compressed earth bricks according to the invention) may be placed in a climatic chamber at 23°C and 33% relative humidity and are 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 0.01 g. After two stable cycles, the samples are removed from the climatic chamber.

[0048] [Math.l]

[0049] where Am is the change in mass of the sample due to the change in humidity relative,

[0050] S is the total exposure area and A% RH is the difference between the humidity levels.

[0051] For the purposes of the invention, the term "process", "calculate", "determine", "display", "transform", "extract", "compare" or more broadly "executable operation" means an action performed by a device or processor unless the context indicates otherwise. In this regard, operations refer to actions and / or processes of a data processing system, for example a computer system or an electronic computer device, which manipulates and transforms data represented as physical (electronic) quantities in the memories of the computer system or other devices for storing, transmitting or displaying information. These operations may be based on applications or software.

[0052] The terms or expressions "application", "software", "program code", and "executable code" mean any expression, code or notation, of a set of instructions intended to cause data processing to perform a particular function directly or indirectly (e.g. after a conversion operation to another code). Examples of program code may include, but are not limited to, a subroutine, a function, an executable application, source code, object code, a library and / or any other sequence of instructions designed for execution on a computer system.

[0053] For the purposes of the invention, the term "processor" means at least one hardware circuit configured to execute operations according to instructions contained in a code. The hardware circuit may be an integrated circuit. Examples of a processor include, but are not limited to, a central processing unit, a graphics processor, an application-specific integrated circuit (ASIC), and a programmable logic circuit.

[0054] The term "computer device" means any device comprising a processing unit or a processor, for example in the form of a microcontroller cooperating with a data memory, possibly a program memory, said memories being able to be dissociated. The processing unit cooperates with said memories by means of an internal communication bus.

[0055] For the purposes of the invention, the term "coupled" means connected, directly or indirectly, with one or more intermediate elements. Two elements can be coupled mechanically, electrically, or linked by a communication channel.

[0056] 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%.

[0057] The construction sector must evolve to optimize its productivity while by addressing societal and environmental challenges. Existing solutions for the manufacture of compressed earth bricks (CEB) require the use of Portland cement at contents generally higher than 8% by dry weight relative to the dry weight of the CEB to achieve expected mechanical strengths. Such concentrations have a significant impact on the ecological footprint of the produced CEB. However, until now, this use at high concentrations has been considered essential given the poor performance of CEBs made with plastic or fiber-type substitutes.

[0058] Faced with this observation, the applicant has developed a new solution allowing the manufacture of compressed earth bricks with reduced or no use of Portland cement. As will be detailed later, the solution developed is based on the preparation of a binder upstream of the production of the mixture with the raw earth, this binder comprising a mixture of raw clay and activation composition and may optionally comprise a composition of calcined metal oxides and a de-flocculant. Such a solution also meets the productivity challenges with a reduced curing time.

[0059] Furthermore, as will be detailed later, the performance of the compressed earth bricks produced can be further improved by pretreatments of the clay matrix and / or the raw earth used.

[0060] Thus, according to a first aspect, the invention relates to a method 200 for manufacturing a compressed earth brick 51. The compressed earth bricks 51 manufactured within the framework of the invention are in particular raw compressed earth bricks 51. Thus, preferably, the manufacturing method 200 according to the invention does not include a firing step (e.g. temperature greater than 500°C). Furthermore, the compressed earth bricks 51 can be considered as being stabilized compressed earth bricks 51.

[0061] The method 200 for manufacturing a compressed earth brick 51 according to the invention may be implemented with devices or systems usually used for manufacturing compressed earth bricks 51. Preferably, it may be implemented by means of the manufacturing system 1 according to the invention which will be described in more detail below.

[0062] As illustrated in [Fig.l], the manufacturing method 200 according to the invention will comprise the following steps: formation 230 of a binder, mixing 240 of the binder with at least two raw earths, and shaping 250 of a compressed earth brick 51 from the mixture.

[0063] Furthermore, the manufacturing method 200 may include steps 210 of acquiring values ​​of characteristics of the raw earth, and of processing 220 of the clay matrix and / or the raw earth and carrying out a cure 260 of the earth brick. compressed 51.

[0064] The manufacturing method 200 according to the invention may comprise a step 210 of acquiring values ​​of characteristics of the raw earth, such as values ​​of the quantity of sand and silt. In particular, this may comprise a measurement of the quantity of sand in the raw earth. In particular, this may comprise a measurement of the quantity of silt in the raw earth.

[0065] Given that the invention involves the preparation of a binder comprising raw clay and which may also comprise sand and silt, the acquisition step 210 generally makes it possible to improve the performance of the compressed earth bricks 51 produced by taking into account the characteristics of the raw earth (e.g. measured sand and silt contents) and possibly the characteristics of the raw clay matrix (e.g. measured sand and silt contents). This can make it possible to increase the mechanical strength of the produced BTC 51.

[0066] In particular, the manufacturing method 200 comprises the step 210 of acquiring, possibly measuring, the mass quantity of sand and silt in the raw clay matrix and in the raw earth. As will be detailed later, this can influence the step 240 of mixing the binder with the raw earth.

[0067] Furthermore, the manufacturing method 200 may include a step of measuring the mass quantity of clay in the raw clay matrix and in the raw earth. As will be detailed later, this may influence the step 240 of mixing the binder with the raw earth.

[0068] The measurement step 210 can be carried out by conventional methods for studying the particle distribution of a soil (e.g. CRAterre recommendations). They can include the use of sieves and sedimentation (e.g. hygrometer, pipette method) and be carried out for example by following the instructions of the standard ASTM D422-63, ASTM D6913-04, ISO 13320:2020, NF X31-107 and possibly the standard NF EN 933-1. This measurement may have been carried out beforehand during the characterization of the raw material. Alternatively or in addition, the measurement can be carried out at the production site and preferably online.For example, optical sensors can be used to analyze the shape and / or color of raw materials, laser granulometers, X-ray scanners can be used to generate an X-ray image, or spectrometers can be configured to generate spectra for different wavelengths such as infrared spectra, near infrared spectra, Raman spectra, XPS spectra (X-ray photoelectron spectrometry), conventional X-ray fluorescence spectra or total reflection. These measurements can, for example, be carried out on a supply line bypass or upstream of preparation.

[0069] As illustrated in [Fig.l], the manufacturing method 200 according to the invention can include a step 220 of treating the clay matrix and / or the raw earth. In particular, the step 220 of treating the clay matrix and / or the raw earth may include a modification of the contents of the different granulometric fractions of the clay matrix and / or the raw earth.

[0070] The treatment step 220 generally makes it possible to prepare the raw material so that the compressed earth bricks 51 have a reduced curing time and improved mechanical performance.

[0071] As described, the clay matrix and / or the raw earth may advantageously have been pretreated. Preferably, the pretreatment is selected from: grinding, sorting, sieving and / or drying of the clay matrix. Preferably, the pretreatment is selected from: grinding, sorting, sieving and / or drying of the raw earth. The pretreatment may for example include fractionation. Fractionation will advantageously be configured so that the materials unsuitable for use in compressed earth brick 51 are extracted. They may be directed to other recovery channels (for example a concrete channel).

[0072] The treatment step 220 can generally be carried out with decomposers, dryers, screens, and / or crushers.

[0073] Drying may in particular allow a reduction in the humidity level of the clay matrix and / or the raw earth without causing a temperature increase above 500°C. The dryer will for example be a rotary dryer.

[0074] The dried clay matrix and / or raw earth may advantageously undergo a screening step, for example in a screen. This step will preferably make it possible to eliminate aggregates with a diameter greater than or equal to 2 cm, more preferably a diameter greater than or equal to 1 cm. The screen will be, for example, a rotary screen.

[0075] Grinding can, for example, be carried out using a hammer mill, a ball mill or even a rod mill. As will be detailed, grinding can be carried out in such a way as to control the D50 of the materials used.

[0076] Preferably, during the formation of the binder, the raw clay matrix may have a D50 less than or equal to 200 pm, preferably less than or equal to 150 pm, more preferably less than or equal to 100 pm, even more preferably less than or equal to 80 pm.

[0077] As mentioned, the raw earth used can also advantageously be pre-treated before being used for the manufacture of a compressed earth brick 51. In particular, the raw earth undergoes two different treatments within the framework of the method aimed at producing at least two raw earths having different granulometric profiles (also called particle size distribution).

[0078] Indeed, in the context of the use of a binder comprising a combination of clay raw earth and an activation composition, possibly with the addition of a composition of metal oxides and deflocculant, it is advantageous to have two raw earths with different particle size profiles. In particular, the prior treatment of at least one raw earth therefore makes it possible to generate two raw earths with different particle sizes.

[0079] In particular, one of the two raw earths has been ground while the other raw earth has not been ground. This may be the same raw earth which, thanks to different prior treatments (e.g. grinding versus non-grinding or fine grinding versus coarse grinding), has different particle size profiles (also called particle size distribution).

[0080] For example, one of the raw earths used, preferably a crushed raw earth, has a D50 of less than 500 pm, preferably a D50 of less than 200 pm, preferably less than or equal to 150 pm, more preferably less than or equal to 100 pm, even more preferably less than or equal to 80 pm. In addition, one of the raw earths used has a D50 of greater than 500 pm, preferably greater than or equal to 750 pm, more preferably greater than or equal to 1 mm, even more preferably greater than or equal to 1.5 mm.

[0081] In particular, one of the raw earths used has a raw clay fraction having a D50 of less than 200 pm, preferably less than or equal to 150 pm, more preferably less than or equal to 100 pm, even more preferably less than or equal to 80 pm. In addition, one of the raw earths used has a raw clay fraction having a D50 of greater than 500 pm, preferably greater than or equal to 750 pm, more preferably greater than or equal to 1 mm, even more preferably greater than or equal to 1.5 mm.

[0082] The use of one or more crushed raw earths with controlled granulometry is important when manufacturing compressed earth brick 51.

[0083] A manufacturing method 200 according to the invention comprises a step 230 of forming a binder comprising a raw clay matrix and an activation composition. It may further comprise a calcined metal oxide composition and / or a deflocculant. In particular, this binder formation step 230 may be carried out a few moments before the use of the binder and its mixing with raw earth. Alternatively, the binder formation step 230 may be carried out well before, and the binder thus formed may be kept in the dry state to be subsequently mixed with raw earth. Preferably, the method according to the invention uses a binder formed extemporaneously. Alternatively, the method according to the invention uses a binder formed at least 6 hours, preferably at least 24 hours before its use and for example on another site.

[0084] As mentioned, in the usual techniques of manufacturing compressed earth brick 51, when a certain mechanical resistance to compression is expected, it is a Portland cement which is used as a binder. This Portland cement is directly mixed with raw earth and then the mixture is used to form bricks. In the context of the present invention, it is necessary to use a binder comprising a mixture of raw clay matrix and an activating composition. In addition, it may also advantageously comprise a composition of calcined metal oxides, and a deflocculant.

[0085] The binder formation step 230 can generally be carried out with a mixing member such as a mixer or a blender, for example a powder blender.

[0086] In particular, as detailed below, the binder formation step 230 may include the use of hoppers, weighing means, volumetric dosing means, transport means such as endless screws and / or aeraulic systems, mixer and / or kneader.

[0087] The formation step 230 is generally carried out over a sufficient period of time to create an intimate mixture between the different constituents of the binder. The parameters for achieving such a result may vary depending on the constituents of the binder.

[0088] The binder formation step 230 may comprise mixing the binder constituents for at least 5 seconds before adding the raw earth, preferably for at least 10 seconds before adding the raw earth, more preferably for at least 20 seconds before adding the raw earth and even more preferably for at least 30 seconds before adding the raw earth. The mixing will generally take place over a period of less than or equal to 20 minutes, preferably for at most 15 minutes before adding the raw earth, more preferably for at most 10 minutes before adding the raw earth and even more preferably for at most 5 minutes before adding the raw earth.

[0089] In particular, the formation step 230 may be carried out in several sub-steps. For example, initially, the formation method 230 may comprise a pre-mixture of a raw clay matrix and an activation composition, preferably an alkaline activation composition. In addition, during this pre-mixture, the method according to the invention may advantageously comprise the addition of a calcined metal oxide composition. Preferably, this pre-mixture will not be hydrated. Finally, the deflocculant, for example in powder form, may be added.

[0090] The following will be detailed preferred or non-preferred embodiments of the raw materials that can be used in the context of several aspects of the present invention.

[0091] Raw clay matrix

[0092] One of the features of the present invention is to use raw clay to form the binder for the raw earth which will serve as the base for the compressed earth brick 51.

[0093] A raw clay matrix may have been prepared at the level of a system 1 of fa compressed earth brick 51 from a clayey soil such as excavated clayey soil. Alternatively, a raw clay matrix may be delivered after preparation to another site.

[0094] The raw clay matrix may for example comprise at least one mineral species selected from: Illite, Kaolinite, Smectite, Bentonite, Vermiculite, Chlorite, Mont-morillonites, Muscovite, Halloysite, Sepiolite, and Attapulgite.

[0095] Preferably, the raw clay matrix comprises at least two types of clays selected from: Illite, Kaolinite, Smectite, Bentonite, Vermiculite, Chlorite, Montmorillonites, Muscovite, Halloysite, Sepiolite, and Attapulgite. This includes so-called interstratified clays which are complex combinations of several clays. Even more preferably, the raw clay matrix comprises at least one mineral species selected from: Kaolinite, Illite, Smectite, Bentonite, Chlorite Montmorillonites, and Vermiculite.

[0096] Table 1 below presents the chemical characteristics of these mineral species. [Tables 1] Raw Clay Matrix Type of clay Composition Illite (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)] Smectite (Na,Ca)0.3(Al,Mg)2Si4O10(OH)2> n H2O Kaolinite Al2Si2O5(OH)4 Bentonite (Na,Ca)0.3(Al,Mg)2Si4O10(OH)2 Vermiculite (Mg,Ca)oj7(Mg,Fe,Al)6(Al,Si)8022(OH)4j n H2O Chlorite (Fe,Mg,Al)6(Si,Al)4O10(OH)8 Muscovite KAl2(AlSi3O10) (OH,F)2 Halloysite Al2Si2O5(OH)4 Sepiolite Mg4Si6O15(OH)2, n H2O Attapulgite (Mg,Al,Fe3+)5[Si8O20](OH)2 (OH2)4n H2O

[0097] According to a preferred embodiment, a binder for compressed earth brick 51 according to the invention will comprise at least two different types of clay and will comprise smectite (Smectite, Bentonite, Montmorillonites), kaolinite, and / or illite.

[0098] In particular, a raw clay matrix according to the present invention may comprise at least 25% kaolinite and / or illite. Raw clay matrices comprising a majority of kaolinite and / or illite will be preferred in the context of the present invention. This may, for example, correspond to a clay matrix comprising more than 25% kaolinite and more than 25% illite, or a matrix clayey matrix comprising more than 40% kaolinite and more than 10% illite. Thus, a raw clay matrix according to the present invention will preferably comprise at least 50% by dry weight of kaolinite and / or illite, more preferably at least 70% by dry weight of kaolinite and / or illite.

[0099] More preferably, the raw clay matrix of a binder for compressed earth brick 51 according to the invention comprises at least one raw clay from the Smectite family and at least one other raw clay selected from Kaolinite, Illite, Chlorite and Vermiculite. In particular, the raw clay matrix comprises smectite, preferably Montmorillonite. The Smectite family includes in particular Montmorillonites and Bentonite. In particular, the clay matrix comprises at least 10% by weight of Smectite, preferably Montmorillonite, preferably at least 20% by weight.Indeed, 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 20% by weight of the raw clay matrix, preferably at least 30% by weight of the raw clay matrix, then the compressed earth brick 51 formed combines mechanical properties and water buffer capacity.

[0100] The type of clay may be determined by methods known to those skilled in the art. In particular, it will be possible to use X-ray diffractometry. For example, the following conditions may be used: - Equipment: Diffractometer, for example a BRUKER D8 ADVANCE (Bragg-Brentano geometry); for example with the following settings: Copper tube (X Kal ~ 1.54 Â) Generator power: 40 kV, 40 mA; Primary optics: fixed slit 0.16°; Soller slit 2.5°; Secondary optics: Soller slit 2.5°; LynXeye XE-T detector - Acquisition parameters: Scan from 4 to 90°20; Scan speed of 0.03°20 / second, Counting time: 480 seconds per step; Rotating sample.

[0101] Preferably, the raw clay matrix used in the context of the invention comprises at least 20% by weight of Smectite, illite and / or Kaolinite, for example at least 30% by weight of Smectite, illite and / or Kaolinite, preferably at least 40% by weight of Smectite, illite and / or Kaolinite, more preferably at least 50% by weight of Smectite, illite and / or Kaolinite and even more preferably at least 60% by weight of Smectite, illite and / or Kaolinite. The percentage by weight corresponding to the cumulative percentage of Smectite, illite and Kaolinite.

[0102] In particular, a clay matrix according to the invention may comprise between 20 and 80% by weight of Smectite, illite and / or Kaolinite, preferably between 30 and 70% by weight of Smectite, Illite and / or Kaolinite or between 40 and 60% by weight of Smectite, Illite and / or Kaolinite, more preferably between 40 and 60% by weight of Smectite, Illite and / or Kaolinite. Preferably, the Smectite may be Montmorillonite.

[0103] The raw clay matrix may, preferably, correspond at least in part to an excavated clay soil, preferably an uncalcined excavated clay soil, such as a treated raw excavated clay soil.

[0104] As has been described, the raw clay matrix may advantageously have been treated, said treatment being selected from: grinding, sorting, sieving and / or drying.

[0105] Preferably, the raw clay matrix used in the binder has been ground.

[0106] Advantageously, the raw clay matrix will comprise crushed raw clay. Preferably, the raw clay matrix may have a D50 of less than or equal to 500 pm, preferably less than or equal to 250 pm, more preferably less than or equal to 100 pm or even more preferably less than or equal to 50 pm.

[0107] In addition, the raw clay matrix may have a D50 greater than or equal to 0.1 pm, preferably greater than or equal to 1 pm, more preferably greater than or equal to 10 pm or even more preferably greater than or equal to 20 pm, more preferably greater than 40 pm. This makes it possible to limit the constraints on industrial production tools dedicated to grinding.

[0108] More preferably, the raw clay matrix may have a D50 of between 10 pm and 500 pm, preferably between 15 pm and 250 pm, more preferably between 20 pm and 150 pm or even more preferably between 20 pm and 50 pm. The presence of a clay ground so as to reach such diameters can make it possible to improve the performance of the compressed earth brick 51 produced according to the invention.

[0109] Advantageously, the raw clay matrix may comprise at least 2% by weight of silt particles, preferably at least 4% by weight, more preferably at least 6% by weight. For example, the raw clay matrix may comprise at most 50% by weight of silt particles, preferably at most 30% by weight, more preferably at most 20% by weight. For example, the raw clay matrix may comprise from 2% to 50% by weight of silt particles, preferably from 4% to 30% by weight, more preferably from 6% to 20% by weight. The silt particles are in particular particles having a diameter of between 2 μm and 200 μm.

[0110] The raw clay matrix may comprise at least 1% by weight of sand, preferably at least 2% by weight, more preferably at least 3% by weight. For example, the raw clay matrix may comprise at most 70% by weight of sand, preferably at most 50% by weight, more preferably at most 40% by weight. For For example, the raw clay matrix may comprise from 1% to 70% by weight of sand particles, preferably from 2% to 50% by weight, more preferably from 3% to 40% by weight. The sand corresponds in particular to particles having a diameter of between 63 pm and 2 mm.

[0111] The use of a crushed raw clay matrix with controlled particle size is important, particularly when preparing the binder for compressed earth brick 51.

[0112] During the binder formation step 230, the dry weight mass proportion of raw clay matrix in the binder is at least 10%. Preferably, the dry weight mass proportion of raw clay matrix in the binder is at least 15%, more preferably at least 20% and even more preferably at least 30%. Preferably, the dry weight mass proportion of raw clay matrix in the binder is at most 70%, more preferably at most 60% and even more preferably at most 50%. For example, the dry weight mass proportion of raw clay matrix in the binder is from 10% to 80%, preferably from 20% to 70%, more preferably from 30% to 70%, and even more preferably from 30% to 65%.

[0113] During the binder formation step 230, the mass proportion by dry weight of raw clay in the binder is at least 5%. Preferably, the mass proportion by dry weight of raw clay in the binder is at least 10%, more preferably at least 20% and even more preferably at least 30%. Preferably, the mass proportion by dry weight of raw clay in the binder is at most 75%, more preferably at most 60% and even more preferably at most 50%, for example at most 40%.

[0114] Activation composition

[0115] Advantageously, the activation composition is an alkaline activation composition. It then preferably comprises at least one base, such as a weak base or a strong base. The alkaline activation 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. The activation composition may be or comprise lime, carbonates, cement such as Portland cement CEM I, composite cement (CEM II), blast furnace cement (CEM III / A) and composite cement (CEM V / A) conforming to standards NF EN 197-1 and NF EN 197-4 or even masonry cement (MC) conforming to standard NF EN 413-1.

[0116] Thus, the activating composition may comprise sulfates, hydroxides, carbonates, silicates, lactates, organophosphorus compounds, lime or combinations thereof.

[0117] Preferably, the activation composition comprises hydroxides and silicates. In particular, the activating composition may comprise a mixture of sodium hydroxide and sodium silicate. When the activating composition comprises silicates, the percentage of silicate in the binder from the activating composition and the percentage of silicate in the binder from the calcined metal oxide composition are counted separately.

[0118] In particular, the activating composition may comprise a mixture of sodium sulfate and sodium chloride.

[0119] Preferably, the activation composition comprises silicates and carbonates. In particular, the activation composition may comprise a mixture of sodium or potassium silicate and sodium or potassium carbonate.

[0120] More preferably, the alkaline activation composition comprises hydroxides.

[0121] The activating composition may comprise an organophosphorus compound such as sodium tripolyphosphate. Preferably, the organophosphorus compound represents at least 2% by weight of the compressed earth brick binder 51.

[0122] Preferably, the activation composition comprises a lactate such as sodium, potassium, and / or lithium lactate.

[0123] Advantageously, the activation composition comprises an oxide of a metal having at least two valence electrons. 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.

[0124] 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 alkali-earth metal, having at least two valence electrons, more preferably at least 60% by weight; even more preferably at least 80% by weight.

[0125] The activating composition may be a liquid composition. In particular, the activating composition may be an aqueous composition. As will be described later, its use may be combined with the addition of water when forming a mixture for compressed earth brick 51. However, alternatively, the activating composition is in solid form, for example in powder form. The indicated percentage of alkaline activating composition corresponds to the dry weight of the composition.

[0126] The step of forming 230 the binder used may comprise the use of at least 5% by dry weight of an activating composition. Preferably, it comprises the use of at least 7% by dry weight of an activating composition. Preferably, it comprises the use of at least 10% by dry weight of an activating composition. Even more preferably, it comprises the use of at least 12% by dry weight of an activating composition, relative to the dry weight of binder.

[0127] The step 230 of forming the binder used may comprise the use of at most 50% by dry weight of an activation composition. Preferably, it comprises the use of at most 45% by dry weight of an activation composition. Preferably, it comprises the use of at most 40% by dry weight of an activation composition. Even more preferably, it comprises the use of at most 35% of an activation composition, relative to the dry weight of binder.

[0128] The step of forming 230 the binder used may comprise the use of 5% to 50% by dry weight of an activation composition. Preferably, it comprises the use of 7% to 45% by dry weight of an activation composition. Preferably, it comprises the use of 10% to 40% by dry weight of an activation composition. Even more preferably, it comprises the use of 12% to 35% of an activation composition, relative to the dry weight of binder.

[0129] The binder for compressed earth brick 51, when its preparation has included the addition of an alkaline activation composition, will preferably comprise at least 0.1% by weight of sodium or potassium, more preferably at least 0.2% by weight of sodium or potassium.

[0130] Calcined metal oxide composition

[0131] A calcined metal oxide composition advantageously comprises metal oxides selected from: FeO, Fe3O4, Fe2O3, Al2O3, MnO, TiO2, MgO and mixtures thereof.

[0132] A calcined metal oxide composition may also comprise aluminosilicates.

[0133] The calcined metal oxide composition is for example selected from blast furnace slag, pozzolans such as volcanic ash, fly ash, silica fume, metakaolin, ash from plant materials such as rice ash, bauxite residues or combinations thereof.

[0134] In particular, the calcined metal oxide composition is for example selected from blast furnace slag, pozzolans such as volcanic ash, fly ash, silica fume, ash from plant materials such as rice ash, bauxite residues or combinations thereof.

[0135] Preferably, the metal oxides are transition metal oxides. The metal oxides may preferably originate from a slag composition blast furnaces, for example, formed during the production of cast iron from iron ore.

[0136] The metal oxide composition is said to be calcined because its constituents have been heated to a temperature above 500°C. For example, the calcined metal oxide composition may include compounds resulting from an industrial process involving combustion, calcination or firing at a temperature above 500°C.

[0137] The calcined metal oxide composition may take the form of a powder.

[0138] The inventors have identified an importance of the mass quantity of metal oxides in combination with the raw clay matrix and the activation composition.

[0139] The step 230 of forming the binder used may comprise the use of at least 5% by dry weight of a calcined metal oxide composition. Preferably, it comprises the use of at least 7% by dry weight of a calcined metal oxide composition. Preferably, it comprises the use of at least 10% by dry weight of a calcined metal oxide composition. Even more preferably, it comprises the use of at least 12% of a calcined metal oxide composition, relative to the dry weight of binder.

[0140] However, unlike other technical solutions favoring a very high concentration of blast furnace slag, fly ash or meta-takaolin, the inventors of the present invention have determined that it is preferable not to exceed certain quantities of calcined metal oxide composition in the binder. In particular, the step 230 of forming the binder used may comprise the use of at most 50% by dry weight of a calcined metal oxide composition. Preferably, it comprises the use of at most 45% by dry weight of a calcined metal oxide composition. Preferably, it comprises the use of at most 40% by dry weight of a calcined metal oxide composition. Even more preferably, it comprises the use of at most 35% of a calcined metal oxide composition, relative to the dry weight of binder.

[0141] The step 230 of forming the binder used may comprise the use of 5% to 50% by dry weight of a calcined metal oxide composition. Preferably, it comprises the use of 7% to 45% by dry weight of a calcined metal oxide composition. Preferably, it comprises the use of 10% to 40% by dry weight of a calcined metal oxide composition. Even more preferably, it comprises the use of 12% to 35% of a calcined metal oxide composition, relative to the dry weight of binder.

[0142] Furthermore, the inventors identified that certain values ​​of ratio between the mass quantity of calcined metal oxide composition and the mass quantity of raw clay matrix made it possible to improve the performance of an earth brick. compressed 51 thus formed. Advantageously, the calcined metal oxide composition and the raw clay matrix are mixed to form a binder for compressed earth brick 51 so that a mass ratio of the calcined metal oxide composition to the raw clay matrix is ​​between 0.2 and 3, preferably 0.4 and 2.5, more preferably 0.5 and 2. In particular, the calcined metal oxide composition and the raw clay matrix are mixed to form a binder for compressed earth brick 51 so that a mass ratio of metal oxides to the clay content is between 0.2 and 3, preferably 0.4 and 2.5, more preferably 0.5 and 2.

[0143] A binder for compressed earth brick 51 according to the invention preferably comprises at most 70% by dry weight of metal oxides, more preferably at most 60% by dry weight of metal oxides and even more preferably at most 50% by dry weight of metal oxides. Similarly, by way of example, a binder for compressed earth brick 51 according to the present invention may comprise less than 30% by dry weight of metal oxides, preferably less than 20%, more preferably less than 10%.

[0144] Deflocculant

[0145] The presence of one or more deflocculant(s) can improve the performance of the compressed earth brick 51 according to the invention and in particular lead to a reduction in the necessary curing time. In addition, the presence of one or more deflocculants can make it possible to reduce the friability of the compressed earth bricks 51 manufactured. Thus, advantageously, a binder for compressed earth brick 51 produced within the framework of the invention comprises a deflocculant, advantageously an organic deflocculant.

[0146] Many compounds can act as deflocculating agents and many are generally known to those skilled in the art.

[0147] In the context of the invention, the deflocculating agent is in particular a non-ionic surfactant such as a polyoxyethylene ether. The polyoxyethylene ether may for example be selected from: a lauryl poly(oxyethylene) ether.

[0148] The deflocculating agent may also be an anionic agent such as an anionic surfactant. In particular, the anionic agent may be selected from: sulfonates, alkylaryl sulfonates, amino alcohols, fatty acids, humates (e.g. sodium humates), carboxylic acids, lignosulfonates (e.g. sodium lignosulfonates), polyacrylates, carboxymethylcelluloses and mixtures thereof.

[0149] The deflocculating agent may also be a polyacrylate. It may then be selected, for example, from sodium polyacrylate and ammonium polyacrylate.

[0150] The deflocculating agent may also be an amine selected for example from: 2-amino-2-methyl-l-propanol; mono-, di- or triethanolamine; isopropa- nolamines (l-amino-2-propanol, diisopropanolamine and triisopropanolamine) and N-alkylated ethanolamines.

[0151] 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.

[0152] The deflocculating agent is preferably 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 organic deflocculating agent is selected from: a polysulphonate, 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 a humate, a lignosulphonate and / or a polyacrylate.

[0153] The deflocculating agent is preferably used in the form of a salt. However, the invention cannot be limited to the deflocculating agents mentioned above or their salts. However, the invention cannot be limited to the organic deflocculating agents mentioned above. Any type of organic deflocculating agent known to those skilled in the art can be used instead of said deflocculating agents mentioned above.

[0154] The deflocculants that can be used according to the present invention may take a solid form or a liquid form. Advantageously, the measuring means are configured to add just the right amount of adjuvant depending on the raw clay matrix used and in particular depending on the measured values ​​of the characteristics of the raw clay matrix.

[0155] The deflocculating agent may, for example, represent from 0% to 5% by dry weight of the binder for compressed earth brick 51. Indeed, in the context of a method according to the invention, there may be an absence of deflocculating agent.

[0156] For example, the deflocculating agent represents at least 0.1% by dry weight of the binder for compressed earth brick 51. Preferably, the deflocculating agent represents at least 0.15% by dry weight of the binder for compressed earth brick 51. More preferably, the deflocculating agent represents at least 0.2% by dry weight of the binder for compressed earth brick 51. Even more preferably, the deflocculating agent represents at least 0.5% by dry weight of the binder for compressed earth brick 51.

[0157] For example, the deflocculating agent represents at most 10% by dry weight of the binder for compressed earth brick 51. Preferably, the deflocculating agent represents at most 7% by dry weight of the binder for compressed earth brick 51. More preferably, the deflocculating agent represents at most 5% by dry weight of the binder for compressed earth brick 51. Even more preferably, the deflocculating agent represents at most 3% by dry weight of the binder for compressed earth brick 51.

[0158] For example, the deflocculating agent represents from 0.1% to 10% by dry weight of the binder for compressed earth brick 51. Preferably, the deflocculating agent represents from 0.15% to 7% by dry weight of the binder for compressed earth brick 51. More preferably, the deflocculating agent represents from 0.2% to 5% by dry weight of the binder for compressed earth brick 51. Even more preferably, the deflocculating agent represents from 0.5% to 3% by dry weight of the binder for compressed earth brick 51.

[0159] In particular, the deflocculating agent represents at least 0.5% by dry weight of the raw clay matrix, preferably at least 0.75% by dry weight of the raw clay matrix, more preferably at least 1% by dry weight of the raw clay matrix, even more preferably at least 2.5% by dry weight of the raw clay matrix, and for example at least 4% by dry weight of the raw clay matrix.

[0160] Cruel Earth(s)

[0161] The raw earth(s) used in the context of the present invention may have multiple origins. For example, the raw earth used may correspond to excavated raw earth. The raw earth used may in particular correspond to recycling sands or even cleaning sands (e.g. pond, lake, rivers, streams, ports, etc.).

[0162] For the manufacture of BTC 51, preferably, the raw earth used does not contain organic matter. For example, it contains less than 5% by dry weight of organic matter. The organic matter can be measured by any method known to the person skilled in the art, for example according to the indications of standard NF P94-055.

[0163] As mentioned, the raw earth will preferably have been sieved. In addition, advantageously at least one of the raw earths used will have been crushed.

[0164] The use of crushed raw earth with controlled granulometry is very important when manufacturing compressed earth brick 51. Thus, a compressed earth brick 51 according to the invention can advantageously comprise crushed raw earth, for example with a D50 of less than 500 μm on the one hand and coarsely crushed or uncrushed raw earth, for example with a D50 of more than 500 μm on the other hand.

[0165] It is possible for the raw earth to contain no clay or very low levels. For example, the raw earth may contain less than 15% by dry weight of clay, preferably from 0% to 10% by dry weight, even more preferably from 0% to 5% by dry weight, even more preferably from 0% to 2% by dry weight relative to the dry weight of raw earth. On the contrary, for certain applications, in particular with improved MBVs, the raw earth may contain at least 10% by dry weight of raw clay, preferably at least 15% by dry weight of raw clay, more preferably at least 20% and even more preferably at least 25% by dry weight, relative to the dry weight of raw earth.

[0166] Generally, at least one of the raw lands used, preferably at least two, may comprise from 5% to 60% by dry weight of raw clay, preferably from 7% to 50% by dry weight of raw clay, more preferably from 10% to 30% by dry weight and even more preferably from 10% to 15% by dry weight, relative to the dry weight of raw earth.

[0167] A raw earth may comprise at least 15% by dry weight of sand. Preferably, a raw earth comprises at least 20% by dry weight of sand, more preferably at least 25% by dry weight and even less preferably at least 40% by dry weight. Preferably, a raw earth comprises at most 95% by dry weight of sand, more preferably at most 90% by dry weight and even more preferably at most 80% by dry weight. Generally, a raw earth used may comprise from 0% to 80% by dry weight of sand, preferably from 5% to 70% by dry weight of sand, more preferably from 10% to 65% by dry weight and even more preferably from 15% to 60% by dry weight of sand, relative to the dry weight of raw earth.

[0168] A raw earth may comprise at least 10% by dry weight of silt. Preferably, a raw earth comprises at least 15% by dry weight of silt, more preferably at least 20% and even more preferably at least 30%. Preferably, a raw earth comprises at most 90% by dry weight of silt, more preferably at most 80% and even more preferably at most 70% by dry weight of silt. Generally, a raw earth used may comprise from 0% to 80% by dry weight of silt, preferably from 5% to 70% by dry weight of silt, more preferably from 10% to 65% by dry weight of silt and even more preferably from 15% to 60% by dry weight of silt, relative to the dry weight of raw earth.

[0169] More broadly, the manufacture of a compressed earth brick 51 according to the invention may include the addition of aggregates which may correspond to natural aggregates, artificial aggregates or even recycled aggregates.

[0170] Aggregates

[0171] The aggregates may also include mineral aggregates, i.e., primarily consisting of mineral matter, and / or plant aggregates, i.e., primarily consisting of matter of plant origin. The aggregates may also include marine aggregates, i.e., primarily consisting of organic or inorganic matter from the seabed, such as siliceous aggregates and calcareous substances (e.g., maerl and shell sands).

[0172] Mineral aggregates may, for example, correspond to sand, gravel, gravel, fillers (or fine materials), powders, fossilized waste and their combination.

[0173] The plant aggregates could, 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 combination.

[0174] In particular, when the compressed earth brick 51 according to the invention comprises plant aggregates, it preferably comprises at least 0.1% by weight of plant aggregates, preferably at least 0.2% by weight of plant aggregates, more preferably at least 0.5% by weight of plant aggregates, and even more preferably at least 0.7% by weight of plant aggregates.

[0175] The manufacturing method 200 according to the invention comprises a step 240 of mixing the binder with at least one raw earth, preferably at least two raw earths. Preferably and as has been presented, the mixing step is carried out with at least one crushed raw earth.

[0176] In particular, during the step 240 of mixing the binder with the raw earth, the binder represents at least 3% by dry weight of the mixture. Preferably, the binder represents at least 4% by dry weight of the mixture, more preferably at least 5% and even more preferably at least 6% by dry weight of the mixture.

[0177] Furthermore, in order to limit the environmental footprint, the binder content is controlled. For example, the binder represents at most 15% by dry weight of the mixture. Preferably, the binder represents at most 12% by dry weight of the mixture, more preferably at most 10% and even more preferably at most 8% by dry weight of the mixture. For example, the binder represents from 3% to 15% by dry weight of the mixture. Preferably, the binder represents from 4% to 12% by dry weight of the mixture, more preferably from 5% to 10% and even more preferably from 6% to 8% by dry weight of the mixture.

[0178] For example, one of the raw earths used, preferably a crushed raw earth, has a D50 of less than 500 pm, preferably a D50 of less than or equal to 250 pm, preferably less than or equal to 150 pm, more preferably less than or equal to 100 pm, even more preferably less than or equal to 80 pm. The D50 may for example be measured by particle size sorting via sieves, for example according to the indications of the ASTM D6913-04 standard. In particular, one of the raw earths used, preferably a crushed raw earth, may have a D10 of less than or equal to 30 pm, more preferably less than or equal to 20 pm, even more preferably less than or equal to 10 pm. The D10 may for example be measured by laser particle size analysis, for example according to the indications of the ISO 13320:2020 standard.

[0179] Furthermore, another of the raw earths used has a D50 greater than 500 pm, preferably greater than or equal to 750 pm, more preferably greater than or equal to 1 mm, even more preferably greater than or equal to 1.5 mm. The D50 may for example be measured by granulometric sorting via sieves, for example according to the indications of the ASTM D6913-04 standard. In particular, one of the raw earths used, preferably a crushed raw earth, may have a D90 greater than or equal to 3 mm, more preferably a D90 greater than or equal to 4 mm, even more preferably a D90 greater than or equal to 5 mm. The D90 may for example be measured by granulometric sorting via sieves, for example according to the indications of standard ASTM D6913-04.

[0180] In particular, the mixing step 240 may comprise the addition of water, for example in the form of spraying water onto the mixture.

[0181] The mixing step 240 generally makes it possible to achieve an intimate mixture between the binder and the raw earth. In addition, the addition of water makes it possible to initiate the setting of the binder within the raw earth or raw earths.

[0182] The mixing step 240 may generally be carried out with a mixer, for example a concrete mixer. The mixing step 240 may comprise an extrusion of the mixture.

[0183] The mixing step 240 is generally carried out for a sufficient time to allow for intimate mixing between the binder and the raw earth or raw earths. For example, the mixing step 240 is carried out for at least 5 seconds after the addition of the raw earth, preferably for at least 10 seconds after the addition of the raw earth, more preferably for at least 20 seconds after the addition of the raw earth and even more preferably for at least 30 seconds after the addition of the raw earth. For example, the mixing step 240 is carried out for at most 60 minutes after the addition of the raw earth, preferably for at most 40 minutes after the addition of the raw earth, more preferably for at most 20 minutes after the addition of the raw earth and even more preferably for at most 10 minutes after the addition of the raw earth.

[0184] In particular, the mixing step 240 may be carried out in several sub-steps. For example, the manufacturing method 200 may comprise the addition in a first step of a first raw earth having certain granulometric properties. The manufacturing method 200 may then comprise the addition in a second step of a second raw earth having different granulometric properties or even of an aggregate, such as a plant aggregate.

[0185] Advantageously, the manufacturing method 200 may comprise, during the mixing step 240, the addition in a first step of a quantity of first raw earth having first granulometric properties and then in a second step the addition of a quantity of second raw earth having second granulometric properties, the quantities of first raw earth and second raw earth being calculated, by one or more processors, as a function of the first and second granulometric properties. Furthermore, preferably, the quantities of first raw earth and second raw earth are calculated by taking into account the granulometric properties of the raw clay matrix used to form the binder for compressed earth brick 51.

[0186] For example, the manufacturing method 200 may comprise, during the mixing step 240, the addition in a first step of a quantity of first raw earth having first granulometric properties and then in a second step the addition of a quantity of second raw earth, having second granulometric properties, the quantities of first raw earth and second raw earth being calculated, by one or more processors, as a function of the quantities of clay, sand and / or silt in the raw clay matrix, in the first raw earth and in the second raw earth.

[0187] The method may also include an addition of aggregate depending on the quantities of clay, sand and / or silt in the raw clay matrix and in the raw earth. In addition, the mixing step 240 may also include an addition of a calculated quantity of raw earth, the quantity of raw earth to be added being calculated depending on the quantities of clay measured in the raw clay matrix and in the raw earth.

[0188] A manufacturing method 200 according to the invention comprises a step 250 of shaping a compressed earth brick 51 from the mixture (i.e. the mixture comprising in particular binder and raw earth). There are many methods of shaping compressed earth bricks 51.

[0189] Compression may be manual or automated through the use of compressors or motors.

[0190] As illustrated in [Fig.2], the shaping 250 of the compressed earth brick 51 may include the following steps: - Place 251 of the mixture in a mold; - Applying 252 pressure to at least one surface of the molded mixture so as to form a compressed earth brick 51; and - Removal 253 of the compressed earth brick 51 from the mold.

[0191] A manufacturing method 200 according to the invention may include a step aimed at vibrating the mold(s) so as to distribute the mixture in the molds. Thus, the mixture is distributed homogeneously in the mold. The vibration step can be carried out with the parameters usually used in the field, in particular, the vibration frequency can vary depending on the targeted properties.

[0192] A manufacturing method 200 according to the invention comprises a step aimed at applying pressure to at least one surface of the molded mixture, preferably to the upper surface. The pressure may be exerted via conventional means for forming compressed earth bricks 51. The pressure exerted may typically correspond to a pressure at least equal to 50 kg / m2 for at least 15 seconds.

[0193] The compression may be carried out, for example, using a fixed press. In this case, the press may be associated with a central unit equipped with probes for controlling the hydrometry of the materials in order to have good control of the consistencies of the mixtures. The production capacities may vary depending on the products; however, the method according to the invention is advantageously configured to manufacture at least 5,000 compressed earth bricks 51 over 12 hours, preferably at least 10,000 compressed earth bricks 51 over 12 hours.

[0194] Alternatively, a hand press may be used.

[0195] Advantageously, a manufacturing method 200 according to the invention may include a step aimed at vibrating the molds again before removing the compressed earth bricks 51 from the molds. This step makes it easier to remove the molds. The vibration step can be carried out with the parameters usually used in the field.

[0196] The method also comprises a step of removing the compressed earth bricks 51 from the molds. This step is preferably carried out just after compressing the mixture or just after vibrating the mold again. For example, the step of removing the compressed earth bricks 51 may be carried out less than 5 minutes, preferably less than 2 minutes, more preferably less than 1 minute, even more preferably less than 30 seconds after the step of placing the mixture in the molds.

[0197] A manufacturing method 200 according to the invention comprises a curing step 260 of the compressed earth brick 51. In particular, the curing step 260 may comprise a wet cure and / or a dry cure. A compressed earth brick 51 according to the invention has a composition such that it can undergo such a cure 260 without risk of cracking.

[0198] Advantageously, the duration of the cure may be reduced when the cure step 260 comprises a cure in an oven at a temperature between 50°C and 100°C and preferably at a relative humidity greater than or equal to 80%.

[0199] The curing step 260 generally allows the compressed earth bricks 51 obtained to mature. Such a step allows the compressed earth bricks 51 time to mature and allows an improvement in the mechanical, physicochemical and hygrometric properties of the bricks. In particular, this step, also called the curing step, can allow an increase in the compressive strength of the compressed earth bricks 51 obtained.

[0200] The curing step 260 can be carried out without any particular installation only by leaving the bricks immobile after having possibly filmed them or not.

[0201] Advantageously, the treatment 260 is carried out over a period of at most 25 days, preferably at most 20 days, more preferably at most 15 days, and in a manner even more preferably at most 10 days, for example at most 7 days. Indeed, the compressed earth bricks 51 according to the present invention have the advantage of reaching a plateau more quickly for their value of mechanical resistance in compression. Thus, the compressed earth bricks 51 according to the present invention, in addition to a lower carbon footprint, have advantageous characteristics for the industrialization of their production and the reduction of operational preparation costs.

[0202] Advantageously, the curing step 260 is carried out so as to obtain a compressed earth brick 51 having a compressive strength greater than or equal to 4 MPa, according to standard NF EN 771-3+A1 / CN.

[0203] Preferably, the curing step 260 may comprise a heat treatment carried out at a temperature above 25°C, more preferably above 30°C. However, in order to respect a favorable energy balance, the heat treatment, which may be carried out within the framework of the curing step, is carried out at a temperature below 100°C, preferably less than or equal to 80°C. For example, the heat treatment is carried out at a temperature between 20°C and 90°C, preferably the heat treatment is carried out at a temperature between 25°C and 80°C; even more preferably between 25°C and 65°C. In addition, the heat treatment may be carried out over the entirety of the curing step 260 but also over a shorter period. Thus, preferably, the heat treatment is carried out for a period of less than 20 hours, more preferably less than 15 hours, and even more preferably less than 10 hours.Ideally, the heat used for the curing step 260 comes from the recovery of fatal heat from other surrounding processes. The curing step 260 may further include a heating step, between 20°C and 90°C, preferably between 40°C and 80°C. This heating step may, for example, be carried out over a period of less than 24 hours, preferably less than or equal to 16 hours, more preferably less than or equal to 12 hours.

[0204] Thus, according to another aspect, the invention relates to a compressed earth brick 51 capable of being manufactured by the method 200 according to the invention. In particular, the invention relates to a compressed earth brick 51 manufactured by the method according to the invention.

[0205] A compressed earth brick 51 according to the invention may have the characteristics resulting from all the embodiments, preferred or not, of the other aspects of the invention and in particular of the manufacturing method according to the present invention.

[0206] The compressed earth brick 51 according to the invention will have a shorter curing time compared to BTCs of the state of the art. In addition, for quantities of low Portland cement, for example less than 5% by dry weight of the BTC, it will have a mechanical resistance to compression greater than BTCs of the state of the technique. The compressed earth brick 51 according to the invention may contain between 0.5 and 4% by dry weight of cement, in particular Portland cement. The quantity of cement in the BTC may, for example, be measured by quantification of the phases by X-ray diffraction (XRD), in particular the phases of belite, alite or even hydrates such as hydrated calcium silicate.

[0207] Preferably, the compressed earth brick 51 according to the invention will comprise at least 5% by dry weight of raw clay. Advantageously, it comprises a deflocculation agent. Preferably, it comprises at least 2% by dry weight of metal oxides, preferably at least 5% by dry weight of metal oxides. The person skilled in the art may, for example, follow the indications of standards NF EN 196-2 and NF EN 15309.

[0208] The compressed earth brick 51 according to the invention will preferably be a solid brick. It may have recesses or horizontal reservations for the production of horizontal chains. Conventionally, a compressed earth brick 51 according to the present invention will have a width of at least 5 cm, a height of at least 2 cm and a length of at least 10 cm. The compressed earth brick 51 may also have a length of at most 40 cm, preferably at most 35 cm, more preferably at most 32 cm. The compressed earth brick 51 may also have a height of at most 17 cm, preferably at most 15 cm, more preferably at most 10 cm. For example, the compressed earth brick 51 may take a shape of substantially 5.4 x 10.5 x 22 cm; 95 x 150 x 315 mm; 95 x 100 x 315 mm; 90 x 140 x 295 mm; 95 x 220 x 220 mm or 5 x 10 x 22 cm (height x width x length).

[0209] Thus, the compressed earth brick 51 can be used to make exterior walls.

[0210] Thus, according to another aspect, the invention relates to a system 1 for manufacturing compressed earth bricks 51 (BTC).

[0211] The BTC manufacturing system 1 according to the present invention will preferably be at least partly automated. Indeed, from weighing values ​​measured in particular by the first weighing means 21, the processors will be able to stop conveyors and initiate a transfer of material to a mixing member 50 such as a mixer.

[0212] The BTC manufacturing system 1 according to the present invention may be a stationary system or a mobile system.

[0213] As illustrated in [Fig.4], a BTC manufacturing system 1 according to the present invention comprises at least one first weighing means 21, and possibly one or more second weighing means 22, distinct from the first weighing means; and it may further comprise a volumetric dosing means 23.

[0214] A BTC manufacturing system 1 according to the present invention will comprise at least two storage assemblies 72 for raw earth. These storage assemblies 72 for raw earth which can for example take the form of an aggregate hopper, a silo or simply a ground storage area.

[0215] Furthermore, a BTC manufacturing system 1 may comprise several silos intended to accommodate the raw materials necessary for making BTCs 51. In particular, a BTC manufacturing system 1 may comprise a raw clay silo 11 intended to accommodate a raw clay matrix, an activator silo 12 intended to accommodate an activation composition, and a metal oxide silo 13 intended to accommodate a calcined metal oxide composition. Alternatively or in addition, the BTC manufacturing system 1 may comprise a binder silo 71 intended to accommodate a binder for compressed earth bricks 51. The BTC manufacturing system 1 may also comprise several aggregate hoppers 73, a water tank, one or more additive tanks and a mixing member 50 such as a mixer.

[0216] Furthermore, a BTC manufacturing system 1 will advantageously be arranged so as to be at least partly controlled by one or more processors 60. These processors 60 are configured to control at least part of the conveyors 111, 121, 131, 711, 721, 731 of the BTC manufacturing system 1 as a function of values ​​generated by the one or more weighing means and / or characteristic values ​​of the raw materials used.

[0217] Advantageously, as shown in [Fig. 4], a BTC manufacturing system 1 according to the present invention may comprise elements for preparing the raw earth or the raw clay matrix. These preparation elements may in particular comprise a de-separator 85, a dryer 84, a screen 83, a grinder 82 and / or a buffer container 81. Under such conditions, the invention also has the advantage of concentrating the operations on the BTC manufacturing site, as close as possible to its future use.

[0218] Elements of preparation of raw earth 4

[0219] In the remainder of this description, the solution developed by the applicant will be mainly based on the use of prepared raw earth which will have undergone one or more treatments to improve its reactivity. In addition, this may concern the preparation of the raw clay matrix. Indeed, in certain cases, the raw clay matrix will be brought to the BTC manufacturing system 1 in the form of pre-treated raw earth 4. As illustrated in [Fig. 4], at the outlet of the storage area 2, the treated raw earth 4 can be brought by a conveyor 113 to the raw clay silo 11.

[0220] As illustrated in [Fig.4], a raw earth 4 may be integrated into the input of the BTC manufacturing system 1 according to the present invention. The raw earth 4 may be analyzed before undergoing the appropriate treatments. For example, a BTC manufacturing system 1 may include a humidity sensor 812, an X-ray fluorescence spectrometer 813 and / or an in-line laser granulometer 814.

[0221] Raw earth 4 can be treated in a clod remover 85 so as to break up the clods.

[0222] The raw earth 4 may also be dried in a dryer 84. The dryer may in particular allow a reduction in the humidity level of the clayey earth without causing the temperature of the excavated clayey earth to rise above 500°C. The dryer 84 will for example be a rotary dryer.

[0223] The dried raw earth 4 may advantageously undergo a screening step within a screen 83. The screen 83 will preferably be configured to eliminate aggregates having a diameter greater than or equal to 2 cm. The screen 83 will for example be a rotary screen.

[0224] The raw earth 4 may advantageously be ground in a grinder 82. The grinder 82 may for example be a hammer mill, a ball mill or even a rod mill.

[0225] Furthermore, a BTC manufacturing system 1 according to the present invention may comprise a magnetic capture device for isolating metallic elements present in the clayey earth. The magnetic capture device may be an electromagnetic capture device of the magnet or electromagnet type.

[0226] Furthermore, the BTC manufacturing system 1 according to the present invention may include means for characterizing the prepared raw earth, for example by measuring a particle size distribution. These means will preferably make it possible to measure:

[0227] - the mass quantity of sand in the raw earth,

[0228] - the mass quantity of silt in the raw earth,

[0229] - the mass quantity of aggregate in the raw earth; and

[0230] - the amount of raw clay in the raw earth.

[0231] These measuring means may be continuous or punctual measuring means.

[0232] Advantageously, one or more of these values ​​will be processed by the processor(s) 60 for the generation of control instructions for the BTC manufacturing system 1.

[0233] Thus, for example, the aggregate conveyors 731 will be controlled so that the sand and aggregates contained in aggregate hoppers (for example from quarries) only serve as a corrective measure. Indeed, the quantities of sand and aggregate already present in the pre-treated raw earths 4 as well as in the raw clay matrix used for the binder can be taken into account.

[0234] BTC Manufacturing System 1 Silos

[0235] Generally, silos contain powdery materials while the aggregates are in vertical or horizontal hoppers.

[0236] In the context of the present invention, a BTC manufacturing system 1 may comprise at least three silos: a raw clay silo 11, an activator silo 12, and a metal oxide silo 13.

[0237] Advantageously, a BTC manufacturing system 1 may comprise several silos of raw clay, activator, and metal oxides. In particular, in addition to a raw clay silo 11, it may comprise: a cement silo (e.g. Portland cement), a blast furnace slag silo, a fly ash silo, a metakaolin silo, a metallite silo and a limestone filler silo.

[0238] The transport of materials stored in silos is preferably carried out by transport devices adapted to powdery materials such as endless screws.

[0239] The raw clay silo 11

[0240] A raw clay silo 11 will preferably be intended to accommodate a raw clay matrix 2. Thus, within the framework of the present invention, a BTC manufacturing system 1 according to the present invention may comprise a raw clay silo 11 containing a raw clay matrix 2.

[0241] In particular, the raw clay silo 11 is a silo suitable for powdery materials. As mentioned, a raw clay matrix 2 may have been prepared at the BTC manufacturing system 1 according to the present invention from a clayey soil such as an excavated clayey soil. Alternatively, a raw clay matrix 2 may be delivered after its preparation to another site.

[0242] As illustrated in [Fig.4], a raw clay silo 11 may be coupled to the one or more second weighing means 22 by a raw clay conveyor 111.

[0243] Preferably, the raw clay conveyor 111 is a conveyor suitable for transporting powdery material; preferably, the raw clay conveyor 111 is selected from: a worm screw, a conveyor belt or any equivalent means.

[0244] The BTC manufacturing system 1 may comprise, upstream of the raw clay silo 11, a humidity sensor 112 configured to measure a humidity level value of the raw clay matrix 2, preferably of the raw clay matrix intended to be added to the raw clay silo 11. A humidity sensor may for example take the form of one or more microwave probes.

[0245] The BTC manufacturing system 1 may comprise, upstream of the raw clay silo 11, an X-ray fluorescence spectrometer configured to measure the quality and homogeneity of the raw clay matrix 2, preferably of the raw clay matrix intended to be added to the raw clay silo 11.

[0246] The BTC manufacturing system 1 may comprise, upstream of the raw clay silo 11, an in-line laser granulometer 114 configured to measure granular values lometry of the raw clay matrix 2, preferably of the raw clay matrix 2 intended to be added to the raw clay silo 11.

[0247] The sensors positioned upstream of the raw clay silo 11 are preferably integrated into a buffer container 81 intended to establish an interface between banana trucks and the raw clay silo.

[0248] The values ​​generated by the sensors positioned upstream of the raw clay silo 11 can be used to generate a digital fingerprint of the delivered raw clay matrix 2.

[0249] The BTC manufacturing system 1 may further comprise a humidity sensor arranged to measure a humidity level value of the raw clay matrix 2 transported to the second weighing means 22. The processor(s) 60 may then be configured to take into account the humidity level value of the transported raw clay matrix to control at least one of the conveyors 11, 121, 131, preferably the raw clay conveyor 111.

[0250] The activator silo 12

[0251] An activator silo 12 will preferably be intended to accommodate an activation composition. Thus, within the framework of the present invention, a BTC manufacturing system 1 according to the present invention may comprise an activator silo 12 containing an activation composition. In particular, the activator silo 12 is a silo suitable for powdered materials. As mentioned, the activation composition 12 may take the form of a powder.

[0252] As illustrated in [Fig.4], an activator silo 12 may be coupled to the one or more second weighing means by an activator conveyor 121.

[0253] Preferably, the activator conveyor 121 is a conveyor suitable for transporting powdery material; preferably, the activator conveyor 121 is selected from: a screw or a conveyor belt or any equivalent means.

[0254] The BTC manufacturing system 1 may comprise a humidity sensor 122 configured to measure a humidity level value of the activation composition. This humidity sensor 122 may for example be positioned upstream of the activator silo 12, to preferably measure the humidity of the activation composition intended to be added to the activator silo 12. Alternatively or in addition, the BTC manufacturing system 1 may comprise, at the activator silo 12 or downstream of the activator silo 12, a humidity sensor 122 configured to measure a humidity level value of the activation composition. The humidity sensor 122 may for example be positioned at the activator conveyor 121 or at the second weighing means(s) 22.

[0255] The metal oxide silo 13

[0256] A metal oxide silo 13 will preferably be intended to accommodate a com- calcined metal oxide position. Thus, within the scope of the present invention, a BTC manufacturing system 1 according to the present invention may comprise a metal oxide silo 13 containing a calcined metal oxide composition.

[0257] In particular, the metal oxide silo 13 is a silo suitable for powdery materials. The calcined metal oxide composition may take the form of a powder.

[0258] As illustrated in [Fig.4], a metal oxide silo 13 may be coupled to the one or more second weighing means 22 by a metal oxide conveyor 131.

[0259] Preferably, the metal oxide conveyor 131 is a conveyor suitable for transporting powdery material; preferably, the metal oxide conveyor 131 is selected from: a worm screw or a conveyor belt or any equivalent means.

[0260] The BTC manufacturing system 1 may comprise a humidity sensor 132 configured to measure a humidity level value of the calcined metal oxide composition. This humidity sensor 132 may for example be positioned upstream of the metal oxide silo 13, to preferably measure the humidity of the calcined metal oxide composition intended to be added to the metal oxide silo 13. Alternatively or in addition, the BTC manufacturing system 1 may comprise, at the metal oxide silo 13 or downstream of the metal oxide silo 13, a humidity sensor 132 configured to measure a humidity level value of the calcined metal oxide composition. The humidity sensor 132 may for example be positioned at the metal oxide conveyor 131 or at the second weighing means(s) 22.

[0261] Aggregate hopper(s) 73

[0262] A BTC manufacturing system 1 according to the present invention may comprise one or more aggregate hoppers 73. The sand and gravel are transported by truck, train or boat from quarries. Generally, upon arrival, they are temporarily stored in a primary storage area before being transported, for example via construction equipment or a conveyor belt, into an aggregate hopper 73.

[0263] An aggregate hopper 73 may be a horizontal hopper or a vertical hopper. An aggregate hopper 73 will be arranged so as to be able to store sand or gravel.

[0264] Conventionally, the aggregates may correspond to natural aggregates, artificial aggregates or even recycled aggregates.

[0265] The aggregates may also include mineral aggregates, i.e., primarily consisting of mineral matter, and / or plant aggregates, i.e., primarily consisting of matter of plant origin. The aggregates may also contain marine aggregates, i.e. mainly made up of organic or inorganic matter from the seabed such as siliceous aggregates and calcareous substances (e.g. maerl and shell sands).

[0266] Mineral aggregates may, for example, correspond to sand, gravel, gravel, fillers (or fine materials), powders, fossilized waste and their combination.

[0267] The 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 a combination thereof.

[0268] As illustrated in [Fig.4], one or more aggregate hoppers 73 are coupled to the first weighing means 21 by one or more aggregate conveyors 731.

[0269] The aggregate conveyor may be of any type capable of moving aggregates. Preferably, an aggregate conveyor 731 may take the form of a belt, or a conveyor belt.

[0270] The BTC manufacturing system 1 may comprise a humidity sensor 732 configured to measure a moisture content value of aggregates. This humidity sensor 732 may for example be positioned upstream of an aggregate hopper 73, preferably to measure the moisture content of the aggregates intended to be added to the aggregate hopper 73. Alternatively or in addition, the BTC manufacturing system 1 may comprise, at the aggregate hopper 73 or downstream of the aggregate hopper 73, a humidity sensor 732 configured to measure a moisture content value of the aggregates. The humidity sensor 732 may for example be positioned at the aggregate conveyor 731 or at the first weighing means 21.

[0271] Although the effect is less strong than for raw clay, a difference in moisture content between the aggregates can lead to a difference in the ratio between aggregates or between the aggregates and the other constituents of the raw clay concrete. Such a difference can have an impact on the quality of the raw clay concrete produced.

[0272] With a measurement of the humidity of the aggregates and therefore of the water content of these aggregates, it is possible to configure the processor(s) 60 so that it controls the BTC manufacturing system 1 in such a way that this water content is compensated.

[0273] Weighing means

[0274] As mentioned, a BTC manufacturing system 1 according to the present invention has at least one first weighing means 21 and possibly one or more second weighing means 22.

[0275] These weighing means 21, 22 advantageously have measurement ranges and different accuracies adapted to the materials they are designed to weigh.

[0276] In particular, the first weighing means 21 may have a measurement accuracy of 2 kg or more, preferably 4 kg or more. Furthermore, the first weighing means 21 may have a capacity of at least 400 kg, preferably at least 600 kg of aggregates. For example, a first weighing means 21 will have a capacity of at least 1 m3, preferably at least 1.5 m3.

[0277] The first weighing means 21 are dedicated to weighing the raw earth 4, the already assembled binder and possibly the aggregates. They can, for example, take the form of a weighing belt or a rocker scale.

[0278] In one embodiment, a BTC manufacturing system 1 according to the present invention comprises a feed belt arranged to transport the aggregates, once weighed, to the mixing member 50 such as a mixer.

[0279] In particular, the one or more second weighing means 22 have a measurement accuracy of 1 kg or less, preferably 0.5 kg or less. This is particularly important in the context of the present invention to obtain a binder for BTC having good performance. Furthermore, a second weighing means 22 may have a capacity of at most 2000 kg, preferably at most 1000 kg, more preferably at most 500 kg. For example, a second weighing means 22 will have a capacity of at most 2 m3, preferably at most 0.5 m3, more preferably at most 0.3 m3.

[0280] In particular, a BTC manufacturing system 1 according to the present invention may be configured to comprise only a single second weighing means 22 coupled to the raw clay conveyor 111, to the activator conveyor 121 and to the metal oxide conveyor 131.

[0281] Adjuvant tank

[0282] A BTC manufacturing system 1 according to the present invention may comprise one or more adjuvant tanks.

[0283] Water tank

[0284] A BTC manufacturing system 1 may conventionally include a water tank. The tank may be arranged to contain mains water (drinking), but also natural water, preferably decanted, or charged water.

[0285] A mixer

[0286] A BTC manufacturing system 1 may conventionally comprise a mixing member 50 such as a mixer. The mixing member will hereinafter be referred to as a mixer 50.

[0287] The mixer 50 of a BTC manufacturing system 1 according to the present invention may be of any type allowing mixing of the raw materials based on raw clay concrete. The tank may be annular, cylindrical, or drum-shaped and the mixing may involve blades but also a vortex, an epi- cycloidal, or a spiral helix.

[0288] In particular, a BTC manufacturing system 1 according to the present invention will comprise a means 502 for measuring a mixing torque value of the mixer 50. This value can preferably be measured continuously, for example via the measurement of the electrical power consumed by the mixer 50.

[0289] Furthermore, certain torques may be more suitable for efficient mixing of raw clay concrete. Preferably, the processor(s) 60 are further configured to adapt or control the transport of one or more admixtures to the mixer as a function of the measured mixing torque value, in particular as a function of the electrical power consumed by the mixer 50.

[0290] Furthermore, a mixer 50 may include a sensor for measuring the humidity of the mixed mixture - for example a microwave probe placed in the mixer 50 - to allow water to be added accordingly. This humidity sensor or more broadly the humidity sensors used in the context of the present BTC manufacturing system 1 may correspond to a microwave probe, a thermogravimetric analysis device or even a system comprising an oven and a scale.

[0291] A means of shaping compressed earth bricks

[0292] A BTC manufacturing system 1 may conventionally include a means 70 for shaping the compressed earth bricks 51.

[0293] The means 70 for shaping the compressed earth bricks 51 may be of any type allowing the previously formed mixture to be shaped into bricks. It may comprise one or more molds as well as one or more pressure means for applying pressure to the mixture.

[0294] Means of analyzing raw materials

[0295] As mentioned, a BTC manufacturing system 1 according to the present invention makes it possible to form BTCs having advantageous properties of mechanical resistance to compression, possibly of MBV and this with a reduced curing time. This requires precise assembly of the raw materials used. Thus, a BTC manufacturing system 1 according to the present invention advantageously comprises means 712, 722 for analyzing and characterizing the raw materials used which can preferably be positioned at the level of the transport means.

[0296] A BTC manufacturing system 1 according to the present invention may comprise, preferably at the level of the transport means, optical sensors capable of analyzing the shape and / or color of the raw materials. A BTC manufacturing system 1 may then comprise a sorter (mechanical, air jet, etc.) controlled by a processor 60 and capable of eliminating undesirable elements detected by the sensor. optical. Alternatively or in addition, the processor(s) 60 may be configured to supply a greater or lesser quantity of raw material to the mixer 50 depending on a calculated characteristic value.

[0297] A BTC manufacturing system 1 according to the present invention may comprise, preferably at the level of the transport means, an X-ray scanner capable of generating a radiographic image. From this radiographic image or from several radiographic images, processors 60 may be configured to calculate a density. A BTC manufacturing system 1 may then comprise a sorter (mechanical, air jet, etc.) controlled by a processor 60 and capable of eliminating undesirable elements according to their calculated density. Alternatively or in addition, the processor(s) 60 may be configured to supply a greater or lesser quantity of raw material to the mixer 50 according to the calculated density value.

[0298] A BTC manufacturing system 1 according to the present invention may comprise, preferably at the level of the transport means, one or more spectrometers. These spectrometers may each be configured to generate spectra for different wavelengths such as infrared spectra, near infrared spectra, Raman spectrum, XPS spectrum (X-ray photoelectron spectrometry), conventional X-ray fluorescence spectrum or in total reflection. From this or these spectra, one or more processors 60 may be configured to calculate a characteristic value of a raw material. The BTC manufacturing system 1 may in particular comprise a sorter (mechanical, air jet, etc.) controlled by a processor 60 and capable of eliminating undesirable elements according to the calculated characteristic value.Alternatively or in addition, the processor(s) 60 may be configured to supply a greater or lesser quantity of raw material to the mixer 50 depending on the calculated characteristic value.

[0299] A BTC manufacturing system 1 according to the present invention may comprise, preferably at the level of the transport means, one or more Geiger counters and one or more magnetometers to determine the behavior under stress from a magnetic field. The processor(s) 60 may be configured to supply a greater or lesser quantity of raw material to the mixer 50 depending on the values ​​thus generated.

[0300] The processor(s)

[0301] As mentioned, the BTC manufacturing system 1 according to the present invention may advantageously be arranged so as to be at least partly controlled by one or more processors 60. In particular, a BTC manufacturing system 1 according to the invention may comprise a central automaton controlled from a dedicated control cabinet.

[0302] Preferably, the processors 60 are configured to control the conveyors 111, 121, 131, 711, 721, 731 as a function of values ​​generated by the one or more weighing means 21, 22.

[0303] The inventors have identified an importance of the mass quantity of metal oxides in the context of the preparation of BTC. Preferably, the processors 60 will be configured to control the BTC manufacturing system 1 so that a batch comprises at least 5% by dry weight of metal oxides, more preferably at least 7% by weight, even more preferably at least 10% by weight. In particular, advantageously, a batch will comprise at least 3% 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 3% by weight can be formed from several different metal oxides. These metal oxides can 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, a mix comprises at least 3% 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 4% by weight. Even more preferably, the at least one metal oxide having at least two valence electrons is selected from aluminum oxides or magnesium oxides.

[0304] Furthermore, the processor(s) 60 may be configured to implement the various embodiments, preferred or not, described in connection with the manufacturing method according to the invention.

[0305] The processor(s) 60 may be configured to take into account the moisture content value of the raw clay matrix and / or the raw earth, preferably the weighed raw clay matrix and / or the weighed raw earth, to control at least one of the conveyors 111, 121, 131, 301, 721, preferably the raw clay conveyor 111 or the raw earth conveyor 721. Thus, depending on the measured moisture content, the processors 60 will be able to control the BTC manufacturing system 1 so that an adequate quantity of water is added to the mixer.

[0306] The use of a combination of raw earths having different grain size profiles in combination with a binder formed from a raw clay matrix had not until recently been considered possible. Such use, particularly in a BTC manufacturing system 1, can benefit from the exploitation of characteristic values ​​of the raw earths and the raw clay matrix such as grain size values ​​of the raw clay matrix 2 or of the raw earths 4, or even X-ray fluorescence. Advantageously, the processor(s) 60 can be configured to take into account a grain size value of the raw clay matrix and / or the raw earths and / or an X-ray fluorescence value to control at least one of the transporters! 11, 121, 131, 301, 721 preferably the raw earth transporter 721 and / or the raw clay transporter 111. Thus, the combination of earths is adapted by the processors 60 according to values ​​measured on the raw clay matrix 2 and the raw earths 4.

[0307] Preferably, the processor(s) 60 of the BTC manufacturing system 1 according to the present invention are further configured to adapt or control the transport of one or more adjuvants to the mixer 50 as a function of the measured X-ray fluorescence values ​​of the raw earths 4.

[0308] More preferably, the processor(s) 60 may be configured to calculate an activity index of the raw earth based in particular on measured X-ray fluorescence values ​​of the raw earth 4. Furthermore, the processor(s) 60 of a BTC manufacturing system 1 according to the present invention may be configured to adapt the transport of one or more adjuvants to the mixer 50 as a function of the calculated activity index of the raw earth 4. Even more preferably, the calculation of the activity index of the raw earth 4 comprises the use of the granulometry and X-ray fluorescence values ​​measured in the BTC manufacturing system 1.

[0309] As mentioned, the raw earths 4 can exhibit significant fluctuation in their characteristics and this can have a significant impact on the performance of the manufactured BTCs. Under these conditions, the BTC manufacturing system 1 according to the present invention is advantageously arranged to allow continuous monitoring of the conformity of the raw materials used.

[0310] Thus, the processor(s) 60 can be configured to compare the values ​​of characteristics of the raw earth 4 (e.g. granulometry and X-ray fluorescence) measured with predetermined thresholds. When the values ​​do not conform to the predetermined thresholds then an alert can be generated.

[0311] In addition, these measured values ​​may be associated with a batch of BTC. Preferably, these measured values ​​are encrypted before being associated with a batch of BTC. Thus, the values ​​can remain confidential while being accessible if necessary.

[0312] In addition, the measured values ​​of raw earth characteristics 4, whether encrypted or not, the production parameters of a batch of BTC and an identifier of said batch concerned may be recorded. The recording may include data security to prevent falsification (e.g. use of certificate or trusted third party).

[0313] Thus, a drift in the quality of the raw material used leading to non-conformities in the concrete generated can be quickly identified and corrected.

[0314] According to another aspect, the present invention relates to a method of controlling a BTC manufacturing system 1.

[0315] Indeed, a BTC manufacturing system 1 according to the present invention is preferably designed to operate in an at least partially automatic manner. A control method according to the present invention may comprise as steps the different embodiments and in particular the configurations of the processors 60 of the BTC manufacturing system 1 according to the present invention.

[0316] The control method according to the present invention may, for example, comprise steps of: • Control of a material flow, for example from a weighing value by the weighing means 21,22; • Measurement and if necessary correction of the humidity of the mixture produced in the mixer 50; and • Control of the mixing of the mixture.

[0317] The binder for BTC may be the first material to be added to the mixer 50.

[0318] Once an adequate quantity of binder has been homogenized in the mixer 50, the crushed raw earth 4 can be added to the binder, then the second raw earth 4 having a particle size profile different from the particle size profile of the crushed raw earth 4 can be added.

[0319] Advantageously, the quantities added may take into account the quantity of binder added but also the characteristic values ​​of the raw earths 4, whether crushed or not. The characteristic values ​​of the raw earths 4 may correspond to a humidity level, X-ray fluorescence values, or even a particle size value.

[0320] Once a batch for BTC is manufactured, it is used by a brick forming means 70 to produce the BTCs.

[0321] According to another aspect, the invention relates to a computer program comprising program code instructions for executing the steps of a method according to the invention when said program is executed on a computer. EXAMPLES

[0322] Preparation of a mixture for a construction element:

[0323] The comparative preparations are prepared in a conventional manner.

[0324] The formulation according to the invention is prepared in two stages. A dry premix of the binder for compressed earth bricks is made between a raw clay matrix and an activation composition, optionally with a calcined metal oxide composition and a deflocculant. In a particular example, the binder for compressed earth brick comprises 60% by weight of raw clay matrix, 40% by weight of activation composition.

[0325] The earth is extracted, characterized (granulometry, Atterberg tests, etc.), screened and sieved to 10 mm. The raw earth is advantageously subjected to at least one grinding operation so as to generate a ground raw earth. The ground raw earth and a raw earth having a different grain size profile (ground or not) are then conveyed to the mixer comprising the binder and mixed with the binder. In a particular example, the mixture comprises 92% by weight of raw earth(s) and 8% by dry weight of binder relative to the total dry weight of the mixture.

[0326] Water is then sprayed until the expected hydration level is obtained. The hydration level can be in the order of 5 to 15%.

[0327] Once the mixture is made, it is sent to a hydraulic press, a doser weighs a predetermined quantity of mixture and places it in the mold. The mixture is compressed, demolded and then the compressed earth brick is left to mature at room temperature, i.e. approximately 20 degrees Celsius for seven days.

[0328] Methodology for measuring the mechanical properties of mixtures for compressed earth bricks:

[0329] Once maturation is complete, the mechanical resistance is measured. The mechanical resistance of a compressed earth brick is its compressive strength, such compression being measured according to standard NF EN 771-3+A1 / CN and is expressed in Mega Pascal (MPa).

[0330] Comparison of the construction elements according to the invention with known construction elements:

[0331] Table 2 below shows, for different types of compressed earth bricks, the properties obtained. [Tables 2] Unstabilized Reference Brick Reference Brick A Reference Brick B Reference Brick B BMTU01 Binder (% dry weight of mix) 0% 8% Lime 8% Portland Cement 3.2% Portland Cement 3.2% Portland Cement 4.8% Raw clay matrix Raw earth (% dry weight of mix) 100% 92% uncrushed raw earth 92% uncrushed raw earth 96.8% uncrushed raw earth 41% Crushed raw earth, D50 < 500 pm 41% Uncrushed raw earth, D50 > 500 pm Compressive strength at 5 days 0.1 MPa 2.2 MPa 3.8 MPa 2.2 MPa 3.6 MPa Compressive strength at 10 days 0.2 MPa 3.5 MPa 4.1 MPa 2.5 MPa 4 MPa Compressive strength at 15 days 0.4MPa 3.8 MPa 4.4 MPa 3.2 MPa 4.2 MPa Compressive strength at 30 days 0.6MPa 3.9 MPa 5.2 MPa 3.7 MPa 4.5 MPa CO2 reduction compared to a brick 99.5% Up to 20% 0% Up to 60% Up to 60% formulated from a 100% Portland cement binder Water resistance NO YES YES Low YES

[0332] Table 2 above illustrates that the compressed earth brick according to the invention reaches an acceptable level of compressive strength (Rc -> 4 MPa) more quickly than a compressed earth brick comprising only raw earth or only a mixture of raw earth and lime or even a compressed earth brick comprising an equivalent quantity of Portland cement.

[0333] Thus, it is more quickly usable and has a reduced carbon footprint compared to a BTC conventionally stabilized with significant quantities of Portland cement.

[0334] The invention may be the subject of numerous variants and applications other than those described above. In particular, unless otherwise indicated, the different structural and functional characteristics of each of the implementations described above should not be considered as combined and / or closely and / or inextricably linked to each other, but on the contrary as simple juxtapositions. Furthermore, the structural and / or functional characteristics of the different embodiments described above may be the subject in whole or in part of any different juxtaposition or any different combination.

Claims

Claims

1. Method for manufacturing (200) a compressed earth brick (51), said method comprising the following steps: - Formation (230) of a binder comprising: • a raw clay matrix (2), and • an activation composition; - Mixing (240) the binder with at least two raw earths (4) having respectively different granulometric profiles; and - Shaping (250) a compressed earth brick (51) from the mixture.

2. Manufacturing method (200) according to claim 1, characterized in that at least one of the two raw earths is a crushed raw earth and in that the crushed raw earth used during the mixing step (240) has a D50 of less than 500 pm, the D50 preferably being measured according to the ATSM D6913-04(2009) standard.

3. Manufacturing method (200) according to one of claims 1 or 2, characterized in that at least one of the raw earths (4) used during the mixing step (240) has a D50 greater than 500 pm, the D50 preferably being measured according to the ASTM D6913-04(2009) standard.

4. Manufacturing method (200) according to any one of claims 1 to 3, characterized in that the activation composition is an alkaline composition comprising one or more compounds having a pKa greater than or equal to 10.

5. Manufacturing method (200) according to any one of claims 1 to 4, characterized in that during the mixing step (240), the mixture comprises 5% or less by dry weight of cement, in particular Portland cement.

6. Manufacturing method (200) according to any one of claims 1 to 5, characterized in that, during the step of forming (230) the binder, the mass proportion by dry weight of raw clay matrix (2) in the binder is at least 30% by dry weight.

7. Manufacturing method (200) according to any one of claims 1 to 6, characterized in that, during the step of forming (230) the binder, the added raw clay matrix (2) has a D50 of less than 400 pm, with D50 preferably measured according to ASTM D6913-04(2009).

8. Manufacturing method (200) according to any one of claims 1 to 7, characterized in that the step of forming (230) the binder further comprises the addition of a calcined metal oxide composition, preferably the mass proportion by dry weight of calcined metal oxide composition in the binder is at most 40%.

9. Manufacturing method (200) according to any one of claims 1 to 8, characterized in that the step of forming (230) the binder further comprises the addition of a deflocculant, preferably the mass proportion by dry weight of deflocculant in the binder is at least 0.01%.

10. Manufacturing method (200) according to any one of claims 1 to 9, characterized in that, during the step of mixing (240) the binder with the raw earth, the binder represents at least 3% by dry weight of the mixture.

11. Manufacturing method (200) according to any one of claims 1 to 10, characterized in that it comprises a step of carrying out a curing step (260) of the compressed earth brick (51), the curing step (260) is carried out over a period of at most 15 days, preferably at most 10 days.

12. Manufacturing method (200) according to the preceding claim, characterized in that the cure (260) is carried out in such a way as to obtain a compressed earth brick (51) having a compressive strength greater than or equal to 4 MPa, according to standard NF EN 771-3+A1 / CN.

13. Manufacturing method (200) according to any one of claims 1 to 12, characterized in that it comprises a step of acquiring a value of at least one granulometric property of the raw clay matrix (2) and the raw earths (4) and in that the step of mixing (240) the binder with the raw earths (4) comprises an addition of calculated quantities of raw earths (4), the calculated quantities of raw earths (4) being calculated by one or more processors (60) as a function of the values ​​of at least one granulometric property previously acquired.

14. Compressed earth brick (51) comprising: - a binder comprising: • a raw clay matrix (2), and • an activation composition; - at least two raw earths (4) having granulo- respectively different metrics.

15. Compressed earth brick (51) according to claim 14, characterized in that it comprises at least 5% by dry weight of raw clay and between 0.5 and 4% by dry weight of cement, preferably Portland cement.

16. Compressed earth brick (51) according to one of claims 14 or 15, characterized in that it further comprises a deflocculation agent.

17. Manufacturing system (1) comprising: - A first particle size distribution modification device arranged to receive a raw earth (4) having a first particle size distribution profile and to treat it so that the treated raw earth has a second particle size distribution profile; - A second particle size distribution modification device arranged to receive a portion of the raw earth having the second particle size distribution profile and to treat it so that the treated raw earth has a third particle size distribution profile;and - A mixing member (50) configured to mix the raw earths having the second and third particle size distribution profiles with a binder comprising a raw clay matrix (2) and an activation composition, the system (1) being further configured to implement a manufacturing method (200) of a compressed earth brick (51) according to any one of claims 1 to 13.;

18. Manufacturing system (1) according to claim 17, characterized in that it further comprises one or more conveyors (111, 121, 131, 711, 721, 731) configured to convey the raw earth having the second particle size distribution profile and the raw earth having the third particle size distribution profile, to the mixing member (50).

19. Manufacturing system (1) according to the preceding claim, characterized in that the one or more conveyors (111, 121, 131, 711, 721, 731) comprise a bypass path positioned after the first particle size distribution modification device and configured to send a portion of the raw earth having the second particle size distribution profile to the mixing member (50) and another portion of the raw earth having the second particle size distribution profile to the second particle size distribution modification device.

20. A manufacturing system (1) according to any one of claims 18 or 19, characterized in that it further comprises a third particle size distribution modification device arranged to receive a portion of the raw earth having the third particle size distribution profile and to treat it so that the treated raw earth has a fourth particle size distribution profile; the one or more conveyors (111, 121, 131, 711, 721, 731) being configured to transport the raw earth having the fourth particle size distribution profile to a mixing member configured to mix the raw earth having the fourth particle size distribution profile with an activating composition.

21. Manufacturing system (1) according to claim 20, characterized in that the third particle size distribution modification device is configured so that the treated raw earth has a D50 less than or equal to 100 pm, preferably the D50 being measured according to the indications of the ASTM D6913-04(2009) standard in combination with the ISO 13320:2020 standard.

22. A manufacturing system (1) according to any one of claims 18 or 19, characterized in that the second particle size distribution modifying device is further arranged to receive a portion of the raw earth having the second particle size distribution profile or the raw earth having the third particle size distribution profile and to process it so that the treated raw earth has a fourth particle size distribution profile; the one or more conveyors (111, 121, 131, 711, 721, 731) being configured to convey the raw earth having the fourth particle size distribution profile to a mixing member configured to mix the raw earth having the fourth particle size distribution profile with a com- activation position.

23. Manufacturing system (1) according to any one of claims 18 to 22, characterized in that it comprises means (722) for measuring characteristics of the raw earths, in particular of the raw earths having the second and third particle size distribution profiles and in that the one or more conveyors (111, 121, 131, 711, 721, 731) are configured to convey the raw earth having the second particle size distribution profile and the raw earth having a third particle size distribution profile to the mixing member (50) as a function of values ​​of characteristics of the raw earths.

24. Manufacturing system (1) according to any one of claims 17 to 23, characterized in that the first particle size distribution modification device is configured so that the treated raw earth has a D50 greater than 500 pm, preferably the D50 being measured according to the indications of the standard ASTM D6913-04(2009).

25. Manufacturing system (1) according to any one of claims 17 to 24, characterized in that the second particle size distribution modification device is configured so that the treated raw earth has a D50 of less than 500 pm, preferably the D50 being measured according to the indications of the ASTM D6913-04(2009) standard in combination with the ISO 13320:2020 standard.

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