阅读说明：本技术 用于选择包含挖掘出的黏土土壤的建筑材料的组成的方法，用于制备这样的建筑材料的方法和系统 (Method for selecting the composition of a building material comprising excavated clay soil, method and system for preparing such a building material ) 是由 M.诺伊维尔 M.梅尔塞 于 2020-03-06 设计创作，主要内容包括：本发明涉及用于选择包含挖掘出的黏土土壤的建筑材料的组成的方法(100),所述建筑材料的组成必须包含适用于挖掘出的黏土土壤的抗絮凝剂和活化剂的量,所述方法包括接收挖掘出的黏土土壤的至少一种理化性质的测量值的步骤(130)和选择适用于挖掘出的黏土土壤的抗絮凝剂的量和活化剂的量的步骤(170)。本发明进一步涉及用于校准用于建立现场建筑材料的组成的计算算法的方法(200)、由挖掘出的黏土土壤形成的建筑材料以及用于制备包含挖掘出的黏土土壤的建筑材料的系统(400)。(The invention relates to a method (100) for selecting a composition of a building material comprising excavated clay soil, which composition must contain an amount of a deflocculant and an activator suitable for the excavated clay soil, the method comprising a step (130) of receiving a measurement of at least one physicochemical property of the excavated clay soil and a step (170) of selecting an amount of a deflocculant and an amount of an activator suitable for the excavated clay soil. The invention further relates to a method (200) for calibrating a calculation algorithm for establishing the composition of an on-site construction material, a construction material formed by an excavated clay soil and a system (400) for preparing a construction material comprising an excavated clay soil.)

1. Method (100) for selecting a composition of a construction material comprising excavated clay soil, the composition of the construction material comprising a deflocculant and an activation dose suitable for excavated clay soil, the method being implemented by computer means comprising a calculation module, the method comprising:

-a step of receiving (130) from the calculation module measurements of at least one physicochemical property of the excavated clay soil; and

-a step of selecting (170), by means of a calculation module, a deflocculating agent and an activating agent suitable for the excavated clay soil based on a comparison of one or more measured values with reference values comprising a correlation between measured values of at least one physicochemical property of the clay soil and the deflocculating agent and activating agent suitable for the clay soil to form a building material.

2. Process according to claim 1, characterized in that said at least one physicochemical property is selected from: clay content in the mined clay soil, clay properties, particle size, impurity content, non-clay mineral fraction content, contaminant content, elemental analysis, metal oxide content, salinity, pH, and total clay exchange capacity in the mined clay soil.

3. Method according to one of claims 1 or 2, characterized in that said at least one physicochemical property is measured on a pre-treated excavated clay soil, said pre-treatment being selected from: crushing, sorting, screening and/or drying the excavated clay soil.

4. A method according to any one of claims 1 to 3, characterized in that it first comprises receiving (140) a desired mechanical property value of the construction material, and in that the step of selecting (170) a deflocculant and an activation dose further comprises excluding (171) deflocculant and activation doses that do not allow the construction material to exhibit the desired mechanical property value.

5. A method according to any one of claims 1 to 4, characterized in that the step of selecting (170), by means of the calculation module, a deflocculating dose and an activating dose suitable for the excavated clay soil comprises implementing a pre-calibrated calculation algorithm.

6. Method according to claim 5, characterized in that the pre-calibrated calculation algorithm has been obtained by implementing a statistical supervised learning method.

7. Method (200) for calibrating a calculation algorithm for determining the composition of a construction material, implemented by a digital device comprising a learning module, said method being characterized in that it comprises:

-a first step (230) of receiving from the learning module measurements of at least one physicochemical property of the excavated clay soil;

-a second step (240) of receiving from the learning module a deflocculating dosage value and an activating dosage value which, when added to the excavated clay soil, allow the formation of building materials;

-a third step (260) of receiving from the learning module measurements of at least one mechanical property of the construction material formed by the excavated clay soil and the deflocculant and activation doses received during the second receiving step (240), the values of at least one physicochemical property of the excavated clay soil being received during the first receiving step (230); and

-a step (270) of creating, by means of the learning module, a correlation between the received measurement values, thereby calibrating the calculation algorithm.

8. Method (300) for preparing a building material from excavated clay soil, the method comprising:

-a step of measuring (310) at least one physicochemical property of the excavated clay soil;

-a step of selection according to the method (100) for selecting the composition of a building material comprising excavated clay soil according to one of claims 1 to 6; and

-a step of mixing (340) the excavated clay soil, the deflocculant and the activator according to the selected composition.

9. The preparation method according to claim 8, further comprising:

-a step of measuring (350) during the mixing step the physico-chemical or mechanical properties of the building material being formed,

-a step of comparing (360) the measured value with a predetermined value of the physicochemical or mechanical property of the building material being formed, and

-a step of adding (370) at least one supplementary ingredient, when the measured value is different (360-n) from a predetermined value of the physico-chemical or mechanical properties of the building material being formed.

10. Building material formed from excavated clay soil, characterized in that it comprises excavated clay soil, an activating agent and a deflocculant, which deflocculant constitutes at least 0.1 wt. -% of the building material, preferably at least 0.25 wt. -% of the building material.

11. Building material according to claim 10, characterized in that it comprises a mixture of different types of clay.

12. Building material according to one of claims 10 or 11, characterized in that it comprises a metal oxide in an amount of at least 2% by weight of the building material, which then preferably corresponds to a building binder.

13. The building material according to any of claims 10 to 12, characterized in that it comprises blast furnace slag.

14. Building material according to claim 13, characterized in that it comprises:

-30-80% by weight of excavated clay soil,

from 0.1% to 10% by weight of a deflocculant, and

-5-10% by weight blast furnace slag;

preferably, the construction material then corresponds to a construction adhesive.

15. Building material according to claim 13, characterized in that it comprises:

-5-20 wt% of raw clay from excavated clay soil;

-0.1-3 wt% of a deflocculant;

-3-15 wt% of an activator;

-25-45 wt% sand; and

-35-55 wt% aggregate;

preferably, the building material corresponds to on-site concrete.

16. Building material according to any of claims 10 to 15, characterized in that it comprises at least 2% by weight of silt particles.

17. Building material according to any of claims 10 to 16, characterized in that the excavated clay soil has been pre-treated, said pre-treatment being selected from the group consisting of: crushing, sorting, screening and/or drying the excavated clay soil.

18. Method (300) for preparing a building material according to any of claims 10 to 17 from excavated clay soil, comprising:

-a step of excavating 320 clay soil;

-a step of screening 330 the excavated clay soil, when the excavated clay soil comprises stones retained by the 2cm screen;

a step of mixing 340 the excavated clay soil, deflocculant and activator.

19. A system (400) for preparing a building material comprising excavated clay soil, the system comprising:

-at least one container (410) comprising excavated clay soil,

-at least one vessel (420) comprising a deflocculant,

-at least one container (430) comprising an active agent,

a mixing device (450), wherein there is an automated transport between the container (410, 420, 430) and the mixing device (450),

-a control module (480) configured to generate an output signal for use by the automated transport vehicle to transport a determined amount of the deflocculant and the activator to the mixing device (450).

20. The system (400) for preparing a construction material according to claim 19, characterized in that it comprises a communication tool configured to receive data on a determined deflocculating dose and a determined activating dose of clay soil suitable for excavation; the control module (480) is configured to generate output signals for use by the automated conveyance to convey the determined deflocculant and activation doses to the mixing device (450).

21. System (400) for preparing a building material according to claim 19, characterized in that it comprises:

-a measuring tool (460) of at least one physicochemical property of the excavated clay soil,

-a computing means (470) adapted to implement a computer program configured to perform the steps of:

-a step of obtaining a measurement value of at least one physicochemical property of the excavated clay soil; and

-a step of determining a deflocculating dose and an activating dose suitable for the excavated clay soil based on a comparison of the one or more measured values with reference values.

Technical Field

The present invention relates to the field of building materials, and more particularly to the field of materials that can be used in construction (e.g. construction adhesives or concrete). The present invention relates to a method for selecting a composition of a building material comprising excavated clay soil. The invention also relates to a method for calibrating a calculation algorithm for determining a composition of a site building material comprising excavated clay soil, to a building material formed from excavated clay soil, and to a system for preparing a building material comprising excavated clay soil.

Background

Cement is the second most consumed resource in the world, producing more than 40 million tons of material every year around the world, and this consumption is constantly increasing driven by the ever increasing demand for housing and infrastructure.

Cement is a binder, usually hydraulic, which hardens and sets when mixed with water. After curing, the cement retains its strength and stability even when exposed to water. Cement is used in a wide variety of ways around the world. Furthermore, the cement production processes are becoming more complex and automated systems for producing various types of concrete have been developed (FR2751911, EP 2296854).

Nevertheless, all conventional cements contain varying percentages of clinker (clinker), ranging from 5% for some blast furnace cements to the lowest 95% for Portland (Portland) cements, which is the most widely used cement throughout the world today. Clinker is the result of firing a mixture containing about 80% limestone and 20% aluminosilicate (e.g. clay). This firing (clinker) is done at temperatures above 1200 ℃, so such a cement production process implies high energy consumption. In addition, the chemical conversion of limestone to lime also releases carbon dioxide. As a result, the cement industry has produced global CO₂About 8% of the emissions. In response to this challenge, industries and researchers are exploring ways to reduce the impact of carbon dioxide emissions from the cement industry.

In addition to these carbon emissions, the management of excavated soil is also a problem in the context of large urban development projects. Although excavated soil is typically stored or used to fill quarries, or used in park development, potential uses are much lower than available. Furthermore, although it has been proposed to use these excavated soils for the production of building materials, this application suffers from the following problems: on the one hand, the structural mechanical strength of raw soil (raw soil) is insufficient and the carbon footprint is not optimal when metakaolin is used.

Indeed, as described in document FR3016376, the proposed raw earth (earth) based cements either have too weak physical properties (such as improved mechanical strength, reduced capillary absorption or reduced permeability to liquids; or they require the addition of a proportion of portland cement to have acceptable mechanical properties.

For metakaolin based cements, the admixture of lime or sodium hydroxide with metakaolin during hydration of the cement will cause a pozzolanic reaction. This reaction improves the binding properties of metakaolin cements. Because of these properties, building materials based on metakaolin have been proposed, in particular comprising flash metakaolin in combination with sodium hydroxide, as described in document FR 3034094. Nevertheless, the formation of metakaolin requires thermal treatment of the kaolinite clays (Kaolinitic clays) to cause dehydroxylation reactions of the kaolinite crystal structure, which causes a negative carbon balance, especially when considering the transport of excavated soil to thermal units.

Therefore, there is a need for a new use of excavated clay soils, which may advantageously allow for reduction of greenhouse gas emissions and the preparation of building materials (e.g. construction binders or site concrete) having a low carbon footprint while having mechanical properties at least comparable to or even better than those of cements commonly used in the construction industry.

[ problem ] to

The present invention is therefore directed to overcoming the disadvantages of the prior art. In particular, the invention aims to provide a method for selecting the composition of a construction material comprising excavated clay soil, which method on the one hand makes it possible to form construction materials such as construction binders to reduce the emission of greenhouse gases (for example carbon dioxide) while imparting mechanical properties suitable for their use in the construction industry, and on the other hand proposes on-site concrete which comprises such binders and which enables improved comfort for the inhabitants compared to concrete formed from portland cement.

The invention also aims to propose a building material formed of excavated clay soil, which has mechanical properties suitable for its use in the construction industry, while constituting a way of recovering (reclaiming) the excavated clay soil.

The present invention also aims to propose a method and a system for preparing a building material comprising excavated clay soil to reduce the emission of greenhouse gases compared to conventional building materials of the portland cement type.

Disclosure of Invention

To this end, the invention relates to a method for selecting a composition of a building material comprising excavated clay soil, the composition of the building material comprising a deflocculant and an activation dose suitable for the excavated clay soil, the method being implemented by a computer device comprising a calculation module, the method comprising:

-a step of receiving from the calculation module measurements of at least one physicochemical property of the excavated clay soil; and

-a step of selecting, by means of a calculation module, a deflocculating agent and an activating agent suitable for the excavated clay soil based on a comparison of one or more measured values with reference values comprising correlations between measured values of at least one physicochemical property of the clay soil and deflocculating agents and activating agents suitable for the clay soil to form a construction material.

Such a selection method has the advantage of being able to select at least part of the constituents of the building material based on excavated clay soil, thereby forming a building material having mechanical properties comparable to those of conventional building materials using clinker, such as building binders or site concrete. Indeed, with the methods of the prior art, the construction materials obtained from excavated soils are generally not sufficiently efficient from a mechanical point of view to allow their widespread use.

Moreover, the components selected by the selection method (i.e. excavated clay soil, deflocculant and activator) allow the formation of building materials with a less energy-consuming preparation method.

Finally, since the construction material comprises excavated clay soil (preferably not subjected to a combustion phase), it advantageously maintains the hygrothermal properties, allowing to improve the comfort of the inhabitants compared to concrete formed of portland cement.

According to other optional features of the selection method:

-said at least one physicochemical form is selected from: clay content in the mined clay soil, clay properties, particle size, impurity content, non-clay mineral fraction content, contaminant content, elemental analysis, metal oxide content, salinity, pH, and total clay exchange capacity in the mined clay soil. Preferably, said at least one physicochemical property is selected from: clay content in the mined clay soil, clay properties, particle size, content of non-clay mineral fractions, elemental analysis, content of metal oxides, salinity, pH, and total clay exchange capacity in the mined clay soil. More preferably, said at least one physicochemical property is selected from: the content of clay in the excavated clay soil, the property of the clay, the particle size, the content of non-clay mineral fractions, the content of metal oxides and the total exchange capacity of the clay in the excavated clay soil. Such physicochemical properties most likely provide deflocculant and activator values appropriate for the excavated clay soil involved.

-measuring said at least one physicochemical property on a pretreated excavated clay soil, said pretreatment being selected from: crushing, sorting, screening and/or drying the excavated clay soil. This advantageously allows manufacturing errors in the measurements to be minimized. Preferably, the pre-treatment comprises at least one (one) classification, e.g. by sieving or sedimentation, more preferably a classification at 50 μm and e.g. at 20 μm.

-it contains beforehand the desired mechanical property value of the building material received, and the step of selecting the deflocculant and the activation dose further comprises excluding deflocculant and activation doses that do not allow the building material to exhibit the desired mechanical property value. Thus, the operator can conveniently set the target performance criteria for the building material, the composition of which is desired. This saves time and improves performance in methods of reclaiming excavated soil for construction applications.

The step of selecting by the calculation module the deflocculating dose and the activating dose suitable for the excavated clay soil comprises implementing a pre-calibrated calculation algorithm.

-obtaining said precalibrated calculation algorithm by implementing a statistical supervised learning method.

According to another aspect, the invention further relates to a method for calibrating a calculation algorithm for determining the composition of a construction material (for example a construction adhesive or in situ concrete), for example implemented by a digital device comprising a learning module, characterized in that it comprises:

-a first step of receiving from the learning module measurements of at least one physicochemical property of the excavated clay soil;

-a second step of receiving from the learning module a deflocculating dosage value and an activating dosage value which, when added to the excavated clay soil, allow the formation of building materials;

-a third step of receiving from the learning module measurements of at least one mechanical property of the construction material formed by the excavated clay soil and the deflocculant and activation dose received in the second receiving step, the values of at least one physicochemical property of the excavated clay soil being received in the first receiving step; and

-a step of creating, by means of a learning module, a correlation between the received measurement values, in order to calibrate the calculation algorithm.

The combination of excavated clay soil, deflocculant and activator allows the production of building materials with considerable mechanical properties, and the selection method according to the invention allows the selection of the right amount of material. However, considering the complexity and variability of the physicochemical properties of the mined clay soil, the inventors developed a method of calibrating the calculation algorithm, allowing to overcome this complexity. Such calibration methods allow for suggested deflocculant and activator quantities highly suitable for excavated clay soils. It should be noted that the order of reception is not important and allows a clear description of the method.

According to another aspect, the invention further relates to a method for preparing a building material from excavated clay soil, the method comprising:

-a step of measuring at least one physicochemical property of the excavated clay soil;

-a selection step according to the method for selecting the composition of a building material comprising excavated clay soil according to the invention; and

-a step of mixing the excavated clay soil, deflocculant and activator according to the selected composition.

Such a simple and fast process allows the emission of greenhouse gases during its implementation to be reduced compared to the implementation in a process for the preparation of conventional building materials of the portland cement type.

According to other optional features of the method of making, the method further comprises:

a step of measuring the physicochemical or mechanical properties of the building material being formed during the mixing step,

a step of comparing the measured values with predetermined values of the physicochemical or mechanical properties of the building material being formed, and

the step of adding at least one supplementary ingredient when the measured value is different from a predetermined value of the physicochemical or mechanical properties of the building material being formed.

Thus, verification of the properties of the building material being formed allows for quality control to be performed on-line (i.e., preferably in real time), thereby ensuring that the formed building material has mechanical properties that are as close as possible to the expected mechanical properties. Indeed, deviations can be identified at the time of mixing and corrected before finalizing (finalized) the building material and more reasonable use.

According to another aspect, the invention relates to a computer program product configured to run the selection method according to the invention.

According to another aspect, the invention relates to a computer program product configured to run the calibration method according to the invention.

According to another aspect, the invention further relates to a building material formed of excavated clay soil, characterized in that the material comprises a deflocculant and excavated clay soil. Preferably, the invention further relates to a building material formed from excavated clay soil, characterized in that the material comprises excavated clay soil, an activating agent and a deflocculant, said deflocculant constituting at least 0.1 wt. -% of the building material, preferably at least 0.25 wt. -% of the building material.

Activators are not systematically found in construction binders or in site concrete because they can react with and be converted into constituents of excavated clay soils. Nevertheless, in some cases, the building material according to the invention formed by excavated clay soil may further comprise an activating agent.

Such a construction material formed of excavated clay soil has mechanical properties suitable for its use in the construction industry, while constituting a means of recovering the excavated clay soil.

According to other optional features of the building material according to the invention, it comprises a mixture of different types of clay.

Furthermore, it may comprise at least 2 wt.%, preferably at least 4 wt.%, more preferably at least 6 wt.% silt (silt) particles. The silt particles are in particular particles having a diameter of from 2 μm to 50 μm.

The building material according to the invention may comprise a metal oxide in an amount of at least 2% by weight of the building material.

The building material according to the present invention may further include blast furnace slag.

The building material according to the present invention may include 30-80 wt% of excavated clay soil, 0.1-10 wt% of a deflocculant, and 5-10 wt% of blast furnace slag. In this case, the construction material preferably corresponds to a construction adhesive.

The building material according to the present invention may include:

-5-20% by weight of raw clay from excavated clay soil;

-0.1-3 wt% of a deflocculant;

-3-15 wt% of an activator;

-25-45 wt% sand; and

-35-55 wt% aggregate;

the building material then preferably corresponds to site concrete.

As shown in the examples (examples), the building materials according to the invention have improved mechanical properties.

Furthermore, the excavated clay soil may advantageously be pretreated, said pretreatment being selected from: crushing, sorting, screening and/or drying the excavated clay soil. The pre-processing may for example comprise a fractionation.

According to another aspect, the invention relates to a method for preparing a building material according to the invention from excavated clay soil, the method comprising:

-a step of excavating clay soil;

-optionally a step of screening the excavated clay soil, when the excavated clay soil comprises stones retained by a 2cm sieve; and

-a step of mixing the excavated clay soil (preferably a fraction smaller than 50 μm), the deflocculant and the activator.

According to another aspect, the invention further relates to a system for preparing a building material comprising an excavated clay soil, the system comprising:

-at least one container comprising excavated clay soil;

-at least one vessel comprising a deflocculant;

-at least one container comprising an activator;

-a mixing device with an automated transport means between the container and the mixing device;

-a control module configured to generate output signals for use by the automated conveyance to convey the determined deflocculant and activation doses to the mixing device.

Advantageously, the system for preparing a construction material according to the invention comprises a communication tool configured to receive data on a determined deflocculating dose and a determined activating dose of clay soil suitable for excavation; the control module is configured to generate output signals for use by an automated conveyance to convey the determined deflocculant and activation dosage to the mixing device.

Preferably, the system for preparing a building material according to the present invention comprises: tool for measuring at least one physicochemical property of excavated clay soil, computing means capable of implementing a computer program configured to carry out the following steps: a step of obtaining a measured value of at least one physicochemical property of the excavated clay soil; and a step of determining a deflocculating dose and an activating dose of the clay soil suitable for excavation based on a comparison of the one or more measured values with reference values.

In particular, the invention further relates to a system for preparing a building material comprising excavated clay soil, the system comprising:

-at least one container comprising excavated clay soil;

-at least one vessel comprising a deflocculant;

-at least one container comprising an activator;

-a mixing device with an automated transport means between the container and the mixing device;

-means for measuring at least one physicochemical property of the excavated clay soil;

-a computing tool adapted to implement a computer program configured to:

a step of obtaining a measurement of at least one physicochemical property of the excavated clay soil, and

a step of determining a deflocculating dose and an activating dose suitable for the excavated clay soil based on a comparison of one or more measured values with reference values; and

-a control module configured to generate output signals for use by the automated conveyance to convey the determined deflocculant and activation doses to the mixing device.

Such a system allows the automatic formation of construction binders or possibly site concrete (with the addition of fillers) from excavated clay soils, where these construction materials have mechanical properties comparable to those of conventional materials with a much larger carbon footprint.

Further advantages and characteristics of the invention will appear on reading the following description, given by way of illustrative and non-limiting example, and with reference to the accompanying drawings, in which:

fig. 1 represents the steps of a method for selecting the composition of a construction material comprising excavated clay soil according to an embodiment of the invention. The dashed steps are optional.

FIG. 2 represents the steps of a method for calibrating a computational algorithm for determining the composition of an on-site building material. The dashed steps are optional.

Fig. 3 represents the steps of a method for preparing a building material from excavated clay soil. The dashed steps are optional.

Fig. 4 represents a method for preparing a building material according to an embodiment of the present invention.

Fig. 5 represents a method for preparing a building material according to an embodiment of the present invention. The dashed steps are optional.

Fig. 6 represents a diagram showing the functional architecture of a system for preparing a building material comprising excavated clay soil according to the invention. The solid arrows represent vehicles and the dashed arrows represent data transmissions or commands, in particular to said vehicles.

Various aspects of the present invention are described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. In the drawings, flowchart 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 flowchart or block diagrams may represent a system, apparatus, module, or code which comprises one or more executable instructions for implementing the specified logical function(s). In some implementations, the functions associated with the blocks may occur out of the order shown in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. Each block of the program diagrams and/or flowchart illustration, and combinations of blocks in the program diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or combinations of special purpose hardware and computer instructions.

Detailed Description

In the rest of the description, the expression "clay soil" must be understood as corresponding to soil originating from soil containing clay, or more generally from loose formations (formations) having a fine grain size and thus containing one or more rock materials based on hydrated silicates or aluminosilicates of lamellar structure. In particular, clay soil may correspond to soil such as sandy-argillaceous silt soil, argillaceous-sandy soil, clay soil. Preferably, the clay soil comprises at least 25% by weight of clay, preferably at least 30% by weight of clay, more preferably at least 40% by weight of clay. The clay weight content can be determined by standard methods of the prior art, such as the particle size method described in the NF X31-107 standard. Furthermore, preferably the clay soil in the framework of the present invention comprises at most 95 wt% clay, preferably at most 90 wt% clay, more preferably at least 80 wt% clay.

Within the meaning of the present invention, the expression "excavated clay soil" corresponds to clay soil obtained after a step of excavating the soil, for example for the purpose of construction, construction or backfilling during levelling and/or earthworking operations. In particular, within the meaning of the invention, the excavated clay soil may or may not be removed from the production site. Preferably and according to an advantage of the invention, the excavated soil is used at a production site or at a distance of less than 200 km. Furthermore, within the framework of the invention, advantageously the excavated clay soil is originally (raw) excavated clay soil, i.e. it has not been subjected to a calcination step. In particular, i.e. it has not been subjected to any thermal pretreatment. This corresponds, for example, to clay soils that have not undergone an increase in temperature above 300 ℃, preferably above 200 ℃ and more preferably above 150 ℃. Indeed, the raw clay may be subjected to a heating step requiring a temperature increase generally substantially equal to 150 ℃, but without the need for a calcination step. Conventionally used clays have a relatively constant particle size distribution (profile) with a size of less than 2 μm. The excavated clay soil may have different particle size distributions. Within the framework of the invention, the excavated clay soil may comprise particles having a size of more than 2 μm, preferably more than 20 μm, more preferably more than 50 μm and for example more than 75 μm, as determined according to the ASTM D422-63 standard. Preferably, the excavated clay soil does not include any aggregates larger than 2cm, as determined according to the NF EN 933-1 standard.

The term "wt%" in relation to excavated clay soil, composition, binder or site concrete is to be understood as a proportion relative to the dry weight of the composition, binder or site concrete. The dry weight corresponds to the weight before addition of water, which is necessary for example for the formation of building materials.

Within the meaning of the present invention, the expression "construction material" corresponds to a construction adhesive or site concrete. The site concrete will in particular comprise fillers, such as aggregates and/or sand.

By "deflocculant" is meant any compound that will dissociate the aggregate and colloid in an aqueous suspension. Deflocculants have been used in situations such as oil drilling or production to make clays more fluid and produce or drill.

By "activator" is meant any component (composition) having the following function: accelerate the dispersion of the aluminosilicate source, promote the formation of stable hydrates with low solubility and the formation of compact structures with these hydrates, thereby increasing the mechanical strength of the material incorporating such activating components.

Within the meaning of the present invention, the term "particle size" corresponds to the distribution of the components (elements ) and particles in clay soil according to the relative proportions by weight of the different classes of particles, which are determined by their size and which constitute the mineral framework of the soil. There are five particle size categories: clay (0-2 microns), fine sand (2-20 microns), coarse sand (20-50 microns), fine sand (50-200 microns), coarse sand (200-2000 microns).

Within the meaning of the present invention, the expression "nature of the clay" corresponds to the chemical and/or mineralogical nature of the clay. This corresponds in particular to the chemical composition of the clay, but also to its mineralogy and to its physical characteristics (for example specific surface area, porosity, morphology). For example, this may correspond to the identification of clays by their common names (e.g., kaolinite, illite, montmorillonite, smectite, bentonite, chlorite, and vermiculite).

Within the meaning of the present invention, the expression "metallic trace elements" corresponds to metallic chemical elements and within the meaning of the present invention it corresponds in particular to metals selected from: iron, lead, mercury, uranium, chromium, copper, cadmium, silver, gold, zinc, nickel or titanium.

Within the meaning of the present invention, the term "substantially equal" corresponds to a value that varies by less than 20%, preferably less than 10%, even more preferably less than 5% with respect to a comparison value.

Within the meaning of the invention, "model" or "rule" orA "calculation algorithm" is understood to be a limited sequence of operations or instructions that make it possible to select deflocculant and activator quantities values, i.e. for example to form a predefined group Y related on the one hand to a score (score) or category as a function of the correlation with the deflocculant dose D and the activator dose a, but also to one or more values E of the physicochemical properties of the excavated clay soil. The limited sequence in which this is done makes it possible, for example, to mark Y₀Is assigned to pass through a set of characteristics D₀、A₀、E₀The observations described, this is due, for example, to the implementation of a function f that can reproduce Y with observed D, A and E.

Y＝f(D,A,E)+e

Where e represents noise or measurement error.

Here, Y may be, for example, the ability to form a building material (yes/no).

Advantageously, the calculation algorithm may establish a predefined set, correlating other values that may be formed from these quantities, for example the value of the mechanical property M of the construction material. Thus, by the formula "M ═ f (D, a, E) + E", the amount of material used to form the building material having predetermined mechanical properties can be selected.

Within the meaning of the present invention, a "supervised learning method" is intended for observations based on n marked observations (X)_1…n,Y_1…n,D_1…n,,A_1…n,,E_1…n) Methods for defining the function f are provided, wherein for example Y ═ f (D, a, E) + E or M ═ f (D, a, E) + E.

Within the meaning of the present invention, "processing," "computing," "determining," "displaying," "extracting," "comparing," or more generally "executable operations" means acts performed by a device or processor, unless otherwise indicated herein. In this regard, operations refer to actions and/or processes in a data processing system (e.g., a computer system or an electronic computing device) that manipulates and transforms data represented as physical (electronic) quantities within the memory of the computer system or other device for storing, transmitting, or displaying information. In particular, the computing operations are performed by a processor in the device, the resulting data are written in corresponding areas in a data memory, and the area or areas may be returned to the user, for example by adapting a Human Machine Interface (e.g. as a non-limiting example, a screen of the connected object), so that such data is formatted. These operations may be based on an application or software.

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 a data process to perform a particular function either directly or indirectly (e.g., after conversion to additional code). Exemplary program code may include, but is not limited to, subroutines, functions, executable applications, source code, object code, libraries, and/or any other sequence of instructions designed for execution on a computer system.

Within the meaning of the present invention, a "processor" means at least one hardware circuit configured to perform operations according to instructions contained in code. The hardware circuit may be an integrated circuit. Examples of processors include, but are not limited to, central processing units, graphics processors, application specific integrated circuits ("ASICs" in accordance with the english terminology), and programmable logic circuitry. A single processor or a variety of other units may be used to implement the present invention.

Within the meaning of the present invention, "coupled" means directly or indirectly linked to one or more intermediate elements. The two elements may be mechanically, electrically coupled, or may be linked by a communication channel.

Within the meaning of the present invention, the expression "human-machine interface" corresponds to any element that allows a person to communicate with a computer, in particular and not exclusively a keyboard, and a tool that allows to perform a display and optionally to select items displayed on a screen with a mouse or a touchpad as a response to commands entered on the keyboard. A further embodiment is a touch screen for directly selecting elements on the screen that are touched by a finger or object, and optionally capable of displaying a virtual keyboard.

In the claims, the term "comprising" or "comprises" does not exclude other elements or other steps.

In the following description, like reference numerals are used to designate like elements. The reference signs should not be construed as limiting the scope of the invention. Furthermore, different features presented and/or claimed may be advantageously combined. Its presence in the description or in different dependent claims does not exclude this possibility.

As mentioned before, it is the current situation that there is a large amount of excavated soil, which is usually considered as waste and thus constitutes an additional burden to the developer when developing the site. Such management and in particular the pollution resulting from the transport of these dredged soils adds to the pollution resulting from the preparation of conventional cements (such as portland).

In the face of this observation, the inventors have identified a method for selecting the composition of a construction material using an excavated clay soil and making it possible to obtain a construction binder having mechanical properties similar to those of conventional cements (for example portland). As will be shown in the examples, the use of this method can produce a construction binder that can be advantageously, but not restrictively, used as a substitute for portland cement, lime or CSA. Thus, waste (i.e., excavated clay) combined with deflocculant and activator in a specific ratio can become a raw material in a construction process.

Furthermore, on the one hand, in view of the method for the production of the building material according to the invention and in view of the use of excavated clay soil, the building material according to the invention has the advantage of having a carbon footprint at least two times lower (two times lower) than most building materials or hydraulic binders (i.e. portland cement) currently used most worldwide. Indeed, the building material according to the invention is mainly made of clay soil and has zero clinker content or a clinker content lower than that of equivalent products and allows reducing CO with equivalent mechanical properties₂Emissions and production costs. Furthermore, said clay soil is preferably not subjected to a calcination step, which is an energy-consuming step that also generates greenhouse gases and more particularly carbon dioxideAnd (5) discharging.

Finally, advantageously, as will be presented in the examples, the construction adhesive according to the invention allows to produce construction materials having mechanical properties at least equal to portland cement and much superior to "low carbon" materials (such as those described previously).

Thus, according to a first aspect, the invention relates to a method 100 for selecting a composition of a building material comprising excavated clay soil. Since the construction adhesive may be subsequently used to form, for example, in situ concrete after the filler is added, the selection method 100 may alternatively correspond to the method 100 for selecting the composition of in situ concrete.

In particular, in order to be able to prepare a building material from excavated clay soil, the composition of the building material must include a deflocculant and an activation dose suitable for the excavated clay soil.

To this end, the method according to the invention, preferably implemented by computer means comprising a calculation module, may comprise the step of receiving 130 from the calculation module measurements of at least one physicochemical property of the excavated clay soil; and a step of selecting 170, by means of the computer module, a deflocculating dosage and an activating dosage suitable for the excavated clay soil.

Furthermore, the method according to the invention may comprise, for example, the following steps: pre-processing 110 mined clay soil, measuring 120 physicochemical properties of the mined clay soil, receiving 140 a desired mechanical property value of a building material, generating 150 a plurality of combinations of deflocculant and activator dosage values, determining 160 a desired mechanical property value of a building material, or determining at least one physicochemical or mechanical property value of a building material being formed.

As shown in fig. 1, the selection method according to the invention may comprise a step of pre-treating 110 the excavated clay soil. Advantageously, therefore, the one or more measurements are derived from a sample of excavated clay soil that has undergone a pre-treatment step 110 of excavated clay soil.

This pre-treatment step may for example comprise or consist of: the excavated clay soil is classified, crushed, sorted (e.g. by colour), sieved and/or dried.

In particular, since in the framework of the invention the clay soil is excavated soil, it may comprise coarse fractions or fractions of large size that may be advantageously removed in the first phase of the method. Thus, in particular, the method according to the invention may comprise removing components having at least one dimension larger than 1cm (centimetre), preferably components having at least one dimension larger than 0.2 cm. Preferably, the method according to the invention may comprise removing components having a size of at least more than 1cm, preferably more than 475 μm (micrometers), more preferably more than 75 μm, the size being determined according to ASTM D422-63 standard.

Furthermore, the method according to the invention may comprise a step of measuring 120 at least one physicochemical property of the excavated clay soil. This step is preferably performed on samples of excavated clay soil, and may be performed on site or in a dedicated laboratory. Indeed, depending on the physicochemical property or properties measured, it may or may not have a transportable instrument.

The measuring step 120 may include, for example, the steps of measuring:

clay content in excavated clay soils, measured for example by granulometry (for example of the type described in the NF X31-107 standard);

the nature of the clay, obtained for example by X-ray diffraction;

-the content of impurities and in particular metallic trace elements, obtained for example by elemental analysis using an ICP-MS apparatus;

-salinity, measuring the conductivity of the clay soil washing water with a conductivity meter;

-pH, measuring pH of clay soil washing water using a pH meter; and

the total clay exchange capacity in the excavated clay soil, measured for example by the so-called methylene blue method according to the NF EN933-9+ a1 standard.

Thus, the measuring step 120 may for example comprise the use of a pH meter, an X-ray diffractometer, a conductivity meter, an electron microscope, a mercury porosimeter, a fluorescence spectrometer, an ICP-MS (Inductively Coupled Plasma Mass Spectrometry in English), an HPLC-MS (liquid chromatography Coupled to Mass Spectrometry), a GC-MS (gas chromatography Coupled to Mass Spectrometry), a specific surface area measurement by the BET method (measurement of specific surface area), a granulometer or a TGA (thermogravimetric analysis) rheometer.

The method according to the invention comprises a step of receiving 130 measurements of at least one physicochemical property of the excavated clay soil. In particular, this step may be implemented by a computing module in the digital device.

The physicochemical properties of the excavated soil for which measurements are received may be selected from: clay content in the excavated clay soil, clay properties, particle size, impurity content, presence of contaminants, mobility limit, plasticity limit, metal oxide content, salinity, pH and total clay exchange capacity in the excavated clay soil. For example, the physicochemical properties of the excavated soil for which measurements are received may be selected from: clay content in the excavated clay soil, clay properties, particle size, impurity content, metal oxide content, salinity, pH, and total clay exchange capacity in the excavated clay soil. Preferably, the physicochemical properties of the excavated soil for which the measurements are received may be selected, for example, from: the content, the fluidity limit and the plasticity limit of the clay in the excavated clay soil. More preferably, the physicochemical properties of the excavated soil for which the measurement values are received include the clay content in the excavated clay soil.

In particular, the content of impurities may correspond to the content of metals and advantageously to the content of metal oxides, such as iron oxides or aluminum oxides.

Preferably, measurements of at least two, more preferably at least three, and even more preferably at least four physicochemical properties of the excavated clay soil are received. Indeed, depending on the number of physicochemical properties considered, the results of the selection method may be of better quality.

The one or more physicochemical properties are physicochemical properties of the soil under extensive study, such as pH, particle size, clay content.

In particular, the method according to the invention comprises receiving 130 a combination of measurements selected from:

-clay content and clay properties in the excavated clay soil;

-total clay exchange capacity and clay content in the excavated clay soil;

-clay content and amount of contaminants;

-pH and clay content of the excavated clay soil; or

-total clay exchange capacity and particle size in the excavated clay soil.

Further, as shown in fig. 1, the method according to the present invention may include receiving 140 a desired mechanical property value of the construction material.

Indeed, in addition to selecting the composition of the building material, the method according to the invention may advantageously also make it possible to select the composition of the building material, thus allowing the preparation of building materials with given mechanical properties. Thus, the user will be able to select the most appropriate amount to obtain a building material that meets his/her needs.

The desired mechanical properties of the building material may for example be selected from: compressive strength, dry shrinkage, set time, flexural strength, tensile strength, Young's modulus, Poisson's ratio.

For example, a method according to the present invention may include receiving a desired compressive strength value for a construction material. This value may for example consist of a lower limit, for example 20MPa (megapascals) or 30MPa, or a fixed value, for example 40 MPa.

Preferably, when the method according to the invention comprises receiving 140 a value of a desired mechanical property of the construction material, the step of selecting 170 a deflocculant and an activation dose further comprises excluding 171 a deflocculant and an activation dose that does not allow the construction material to exhibit the desired value of the mechanical property. For example, this may correspond to selecting all values of a and D by a calculation algorithm that allows obtaining a value of M ═ 40MPa from the measurement of E. Alternatively, without a calculation algorithm, this may include filtering out from the database all values that would cause the value of M to be below 30 MPa.

The step of receiving 130 measurements of at least one physicochemical property of the excavated clay soil may be followed by the step of generating 150 a plurality of combinations of deflocculant dosage values on the one hand and activator dosage values on the other hand. After generating the plurality of values, the calculation module may implement a value selection step 170 as described below.

Furthermore, the method according to the invention may comprise a step of determining 160 at least one physicochemical or mechanical property value desired for the construction material. This step is implemented, for example, by a calculation module.

From the measurements of the physicochemical properties of the excavated clay soil and from the values of the deflocculant and activator quantities produced, it is then possible to determine the values of the mechanical properties of the construction material formed by the excavated soil and the deflocculant and activator quantities considered.

The method according to the invention comprises a step of selecting 170 a deflocculating dose and an activating dose suitable for the excavated clay soil. This step can be implemented, for example, by a computing module.

The deflocculant and activator amounts may correspond to volume, mass or ratio. Preferably, the amount corresponds to a proportion relative to the amount of excavated clay soil added to the building material composition. Alternatively, if the quantity corresponds to a volume or a mass, it is correlated to the amount of excavated clay soil added to the building material composition.

Further, selecting 170 a deflocculating agent dose and an activating agent dose may include determining the nature of the deflocculant and/or activating agent to be added. For example, the properties of these agents may correspond to a class of chemical molecules or a particular chemical molecule or combination of molecules.

Indeed, the deflocculant may be a combination of molecules and the selection of the deflocculant amount may correspond to the selection of the amount of each molecule making up the deflocculant. The same applies to the activator, which may be a single molecule or a plurality of molecules.

Advantageously, the selection is made on the basis of a comparison of one or more measured values of the physicochemical properties of the excavated clay soil with reference values. In particular, the reference value comprises a correlation between a measured value of at least one physicochemical property of the clay soil and a deflocculant and an activation dose suitable for said clay soil to form a construction material.

Anti-flocculant agent

Many compounds can be used as deflocculants and many are well known to those skilled in the art.

Within the framework of the invention, the deflocculant is in particular a nonionic surfactant, for example a polyoxyethylene ether. The polyoxyethylene ether may for example be selected from: poly (oxyethylene) lauryl ether.

The deflocculant may also be an anionic agent such as an anionic surfactant. In particular, the anionic agent may be chosen from: alkyl aryl sulfonates, amino alcohols, carbonates, silicates, fatty acids, humates (e.g., sodium humate), carboxylic acids, lignosulfonates (e.g., sodium lignosulfonate), polyacrylates, phosphates, or polyphosphates such as sodium hexametaphosphate, sodium tripolyphosphate, sodium orthophosphate, carboxymethylcellulose, and mixtures thereof.

The deflocculant may also be a polyacrylate. It may be selected from, for example, sodium polyacrylate and ammonium polyacrylate.

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

The deflocculant may also be a silicate, such as sodium silicate, sodium metasilicate, or sodium trisilicate.

Alternatively, as previously described, the deflocculant may be a mixture of compounds, for example a mixture comprising at least two compounds selected from: nonionic surfactants, anionic agents, polyacrylates, amines and organic phosphorus compounds.

In particular, the deflocculant may be a mixture of sodium silicate and sodium carbonate.

Preferably, the deflocculant is selected from: lignosulfonates (e.g., sodium lignosulfonate), polyacrylates, humates, and mixtures thereof.

The deflocculant is preferably in the form of a salt.

However, the present invention is not limited to the above-mentioned deflocculant, and any type of deflocculant known to those skilled in the art may be used in place of the above-mentioned deflocculant.

Activating agent

It is the activating agent in combination with the excavated clay soil and the deflocculant that imparts the building material with its desired mechanical properties.

Without being limited by theory, the activator may allow the formation of a network between the clay sheets, which imparts its mechanical properties to the building material according to the invention.

In particular, the activator may comprise a metal oxide and/or be a basic activating component (composition).

Preferably, the metal oxide is a transition metal oxide. More preferably, the metal oxide is selected from: iron oxides such as FeO, Fe₃O₄、Fe₂O₃、Fe₂O₃Aluminum oxide Al₂O₃Manganese (II) oxide MnO, titanium (IV) oxide TiO₂And mixtures thereof.

The metal oxide may preferably be derived from a composition such as blast furnace slag formed during production of pig iron from iron ore.

The metal oxide is present in an amount of at least 2% by weight of the building material, preferably at least 5% by weight of the building material, more preferably at least 10% by weight of the building material.

When the activator is a basic activating component (composition), the basic component (composition) may preferably comprise a compound having a pKa of greater than or equal to 10, more preferably greater than or equal to 12, even more preferably substantially equal to 14.

The alkaline component may, for example, comprise an organophosphorus compound, such as sodium tripolyphosphate, described for short by NaTPP.

In particular, the activator may comprise a mixture of sodium hydroxide and sodium silicate.

Advantageously, the activator may be a basic activating component further comprising a metal oxide. As will be shown in the examples, construction adhesives prepared from such activators have good mechanical properties. Thus, preferably, the activator may comprise a metal oxide and at least one compound having a pKa greater than or equal to 10.

Further, the selecting step 170 may include determining 172 an amount of additive to be incorporated into the building material composition. Indeed, the selection method according to the invention makes it possible to obtain a building material composition comprising certain additives in a defined concentration. These additives allow the chemical and/or mechanical properties of the final building material to be altered.

The additives are selected, for example, from: plasticizers, synthetic or natural rheology retention agents, anti-shrinkage agents, water retention agents, air entraining agents, synthetic resins, pigments and mixtures thereof.

The plasticizer may, for example, be a polyacrylate, a polynaphthalenesulfonate, a polycarboxylate or a polyphosphate.

In addition, the selecting step 170 may include determining 173 an amount of filler to be incorporated into the mixture to form the in situ concrete. These fillers allow the mechanical properties of the final building material to be modified.

The filler may for example be selected from recycled or non-recycled aggregates, powders, sand, gravel, crushed concrete and/or fibres.

The fibers are for example selected from: plant fibers such as cotton, flax, hemp, cellulose, bamboo, miscanthus, synthetic fibers such as metal, glass, carbon, polypropylene fibers, and mixtures thereof. The presence of fibers may allow the formation of building materials with improved mechanical and insulation properties.

Advantageously and as previously described, the step of determining 170 a deflocculating dose and an activating dose suitable for the excavated clay soil comprises implementing a pre-calibrated calculation algorithm.

This computational algorithm can be built from different learning models, in particular partitioning, supervised or unsupervised models.

The unsupervised statistical learning model may, for example, be selected from an unsupervised gaussian mixture model, a hierarchical bottom-up classification (i.e. a hierarchical clustering in english terminology), a hierarchical top-down classification (i.e. a hierarchical clustering in english terminology).

The statistical supervised learning model may for example be selected from a kernel method (e.g. Support Vector Machines (SVM), kernel ridge regression) as described for example in Burges,1998(Data Mining and Knowledge learning. a kernel on Support Vector Machines for Pattern Recognition), a set (set) method (e.g. Bagging, Boosting, Decision Trees, Random form) as described for example in Brieman,2001(Machine learning. Random forms), or a neural network as described for example in Rosenblatt,1958(The term: a statistical model for information storage and organization in The fibre).

Preferably, the pre-calibrated calculation algorithm is obtained by implementing a statistical supervised learning method.

Thus, according to another aspect, the invention relates to a method 200 for calibrating a calculation algorithm. This calculation algorithm is specifically intended to determine the composition of the building material. The calibration algorithm according to the invention can be implemented in particular by a digital device comprising a learning module.

As shown in fig. 2, such a calibration method according to the invention comprises a step of receiving 230 measurements of at least one physicochemical property of the excavated clay soil.

Preferably, a plurality of measurements are received, and in particular values of at least two, more preferably at least three and even more preferably at least four physicochemical properties of the excavated clay soil. Indeed, depending on the number of physicochemical properties considered, the quality of the calibration method will be better.

The calibration method according to the invention further comprises the step of receiving 240 a deflocculating dose value and an activating dose value. These values correspond to the amount of agent that makes it possible to form the building material once added to the excavated clay soil.

The deflocculant and activator amounts may correspond to volume, mass or ratio. Preferably, the amount corresponds to a proportion relative to the amount of excavated clay soil added to the building material composition. Alternatively, if the quantity corresponds to a volume or a mass, it is correlated to the amount of excavated clay soil to be added to the building material composition. Further, receiving 240 a deflocculant and activator quantity value may include receiving a property of the deflocculant and/or activator. For example, the properties of these agents may correspond to a class of chemical molecules or a particular chemical molecule or combination of molecules.

These values can be obtained by tests as will be described in the examples section. Only those amounts of agent that can form the building material are included in the calibration method.

Indeed, the calibration method may comprise the step of forming 250 the building material from the received values. Alternatively, and preferably, various combinations of agent magnitudes are tested on various mined clays, forming a database that can be used as input data to a calibration method.

The method then includes the step of creating 270 a correlation between the received measurements to calibrate the calculation algorithm. This measurement-based correlation step allows a computational algorithm to be constructed from the statistical learning model. Thus, the calculation algorithm may take the form of a function f of an equation of the type

Y＝f(E,A,D)

Preferably, as shown in fig. 2, prior to the creating step 270, the calibration method according to the present invention may further comprise the step of receiving 260 a measured value of at least one mechanical property of the formed construction material. In fact, the calibration method according to the invention can also use one or more measurements of the resulting construction material, in addition to the quantity of agent used and one or more values of the physicochemical properties of the excavated clay soil. Thus, the calculation algorithm may take the form of a function f of an equation of the type:

M＝f(E,A,D)

preferably, a plurality of measured values of the building material, and in particular values of at least two, more preferably at least three and even more preferably at least four physico-chemical properties of the building material, are received 260.

Furthermore, as shown in fig. 2, the calibration method according to the invention may comprise a step of pre-treating 210 a clay soil sample, which may be followed by a step of measuring 220 at least one physicochemical property of the clay soil. Further, once the dependencies are established, the dependencies can be saved 280 on a storage medium such as RAM or non-volatile memory.

Advantageously, the calibration method according to the invention may comprise a step of updating 290 the calculation algorithm by repeating the previous steps described hereinbefore, and said previous steps being at least: receiving 230 measurements of at least one physicochemical property of the excavated clay soil, receiving 240 a deflocculation dose and an activation dose forming a building material when added to the excavated clay soil, and creating 270 a correlation between the received measurements to calibrate the calculation algorithm.

According to another aspect, the invention relates to a method 300 for preparing a building material from excavated clay soil.

As shown in fig. 3, an advantage of such a process according to the invention is the so-called low-carbon process, i.e. a process in which the greenhouse gas emissions, such as especially carbon dioxide emissions, are reduced compared to the greenhouse gas emissions in the known process for preparing construction adhesives. Such a reduction in greenhouse gas emissions is in particular associated with the absence of a calcination stage, which is in particular energy-intensive.

Furthermore, the preparation of the construction adhesive according to the invention may allow the preparation of site concrete which is at least partially made from raw materials from the construction site to be carried out. Such properties further reduce the environmental footprint of the concrete produced. Once the deflocculating agent and the activating agent suitable for the excavated clay soil have been selected, the preparation of the construction material from the excavated clay soil is continued according to conventional methods.

The preparation method according to the invention may comprise a step of measuring 310 at least one physicochemical property of the excavated clay soil.

Such a step may be performed as early as the mixing step 340. This is the case, for example, if preliminary studies are carried out and it is not necessary to use excavated soil quickly. Alternatively, the step of measuring 310 at least one physicochemical property of the excavated clay soil may be performed immediately before the step of selecting 100 a composition of the building material, which corresponds to the step of implementing the method 100 and the mixing 340 according to the invention. This is the case, for example, in an automated method for producing building materials from excavated clay soil, in which the excavated clay soil is analyzed using a (in line with) mobile measuring device and is then continuously mixed with the selected amount of agent, so that the building material is formed in a very short time.

Preferably, a plurality of measurements are received, and in particular values of at least two, more preferably at least three, and even more preferably at least four physicochemical properties of the excavated clay soil.

Furthermore, as shown in fig. 3 and 4, the preparation method according to the invention may comprise selecting 100 according to the invention a composition of the building material comprising excavated clay soil.

Furthermore, it may comprise the step of mixing 340 the excavated clay soil, deflocculant and activator according to the selected composition.

In the mixing step, water may be added in such a manner that: the ratio of the mass of water to the mass of the building material is made to be less than 1 and, for example, 0.4 to 0.8. Furthermore, water may advantageously be added after dry-mixing the excavated clay soil and the deflocculant.

Preferably, therefore, the method according to the invention may comprise a mixing step, so as to obtain a suspension of dispersed or deflocculated dredged clay soil. In the mixing, preferably, a deflocculant is added before the activator, so that the activator is mixed with the dispersed or deflocculated excavated clay soil.

This mixing step 340 of the clay suspension can advantageously be carried out, but not limitatively, in an apparatus chosen from: mixers and truck mixers, or more generally in any device suitable for mixing clay soils.

Preferably, the preparation method may comprise the step of screening 330 the excavated clay soil. This screening step occurs before the mixing step 340 and before or after the measuring step 310. In particular, it is implemented in such a way that: aggregate having a diameter greater than 20mm (millimeters) is removed.

In a broad sense, the preparation method may comprise the step of preparing the excavated clay soil, wherein the preparation may comprise, for example: drying, grinding, sieving and storing.

Preferably, the pre-treatment or screening step comprises at least one (one) classification, such as sieving, more preferably a classification such as 50 μm sieving. Advantageously but not limitatively, the components or particles thus screened (for example sand and/or aggregate fractions) can be reused in the formulation of building materials and in particular site concrete. The fraction which is most interesting for the preparation of building materials is the fraction which is not retained by the sieve. Thus, the method 300 according to the invention for preparing a building material from excavated clay soil will advantageously comprise a step of grading 335 the optionally screened excavated clay soil, preferably at 50 μm.

Alternatively, not the excavated clay soil may be pretreated, but all clay soil may be used to obtain the building material. In this case, the method allows the production of concrete on site.

This advantageously allows to recover all excavated clay soils, in particular in case the physicochemical properties associated with said excavated clay soils are sufficient to obtain building materials with the required mechanical properties. In this way, all the soil can be recovered from the beginning without the need to separate the clay in order to process it and formulate it into a material.

As shown in fig. 5, the method 300 according to the invention for preparing a building material from excavated clay soil will advantageously comprise:

-a step of excavating 320 clay soil;

-a step of screening 330 the excavated clay soil, when the excavated clay soil comprises stones retained by the 2cm screen;

a step of mixing 340 the excavated clay soil (preferably a fraction smaller than 50 μm), the deflocculant and the activator.

Furthermore, the preparation method may advantageously comprise a step of treating the contaminants. Such a contaminant treatment step allows the concentration of contaminants, such as trace amounts of metal elements, hydrocarbons (e.g. polycyclic aromatic hydrocarbons and C10-C40), PCB (polychlorinated biphenyls), BTEX (benzene, toluene, ethylbenzene, xylene), TOC (total organic carbon) in the excavated clay soil to be reduced.

Furthermore, conventionally, before, simultaneously with or after the addition of the activating component (composition), the method according to the invention may comprise the addition of additives or fillers for modifying the mechanical properties of the final building material.

Advantageously, the preparation method may comprise measuring 350 one or more values of the physico-chemical or mechanical properties of the building material during the mixing step (i.e. the building material is being formed), comparing 360 the measured values with predetermined values of the physico-chemical or mechanical properties of the building material being formed.

Thus, quality control of the building material being formed can be performed.

Furthermore, when the measured values differ by a predetermined value of the physico-chemical or mechanical properties of the building material being formed, the preparation method may comprise the step of adding 370 at least one supplementary ingredient.

Herein, the supplementary ingredient may for example be selected from: deflocculant, activator and excavated clay soil, thereby changing the predetermined composition. The supplemental ingredient may also be selected from: additives or fillers as described hereinbefore.

This ensures that the building material being formed will have mechanical properties as close as possible to the desired mechanical properties. Indeed, deviations can be identified at the time of mixing and corrected prior to use of the building material.

Further, as shown in fig. 4, the method is completed by the step of recovering 380 the formed building material.

According to another aspect, the invention relates to a system 400 for preparing a building material comprising excavated clay soil. Alternatively as described, the invention relates to a system 400 for preparing on-site concrete comprising excavated clay soil.

Such a method according to the invention shown in fig. 5 may comprise containers 410, 420, 430 for the various components of the building material. For example, it may include at least one container 410 for excavated clay soil, at least one container 420 for deflocculant, and at least one container 430 for activator. Furthermore, it may comprise at least one container 440 for fillers and/or additives. Further, the system may include a cleaning vessel for containing a cleaning solution.

Especially in the case of excavated clay soil, the container 410 may not be an article but merely a place where the excavated clay soil is stored. The container may also be selected from tanks, containers, barrels, silos.

Furthermore, the system according to the invention comprises a mixing device 450. In particular, such a device is capable of homogenizing and/or stirring the precursor components of the construction adhesive.

This mixing device 450 is specifically coupled to an automated conveyance (represented by the arrows between the containers 410, 420, 430, 440 and the mixing device 450, respectively) located between the containers 410, 420, 430 and the mixing device 450. These vehicles may be, for example, flexible or inflexible pipes, belts, conveyors, or screw conveyors. Further, in conjunction with the vehicle, the system may include pumps, valves, solenoid valves, and flow restrictors. In particular, the flow restrictors may be arranged to switch with each vehicle function to independently adjust the amount of each ingredient delivered to the mixing device 450.

Furthermore, the system according to the invention may comprise a measuring tool 460 of at least one physicochemical property of the excavated clay soil. Such measuring means 460 may be, for example, a pH meter, an X-ray diffractometer, a conductivity meter, an electron microscope, a mercury porosimeter, a fluorescence spectrometer, an ICP-MS, an HPLC-MS, a GC-MS, a specific surface area measurement by the BET method, a granulometer or a rheometer.

Furthermore, the system according to the invention may comprise a calculation tool 470, the calculation tool 470 being adapted, preferably configured, to implement a computer program configured to perform the steps of:

-a step of obtaining a measurement value of at least one physicochemical property of the excavated clay soil; and

-a step of determining a deflocculating dose and an activating dose suitable for the excavated clay soil based on a comparison of the one or more measured values with reference values.

Furthermore, the system according to the invention comprises a control module 480 configured to generate an output signal for use by the automated transport. Such an output signal would allow the system to deliver a determined amount of the deflocculant and activation agent to the mixing device 450. Furthermore, they may allow for transporting a predetermined amount of excavated clay soil to the mixing device 450.

Preferably, the system for preparing a building material according to the present invention may further comprise: sieves, preferably dense sieves, soil breakers, planetary mixers.

More preferably, it may comprise a soil breaker. In particular, the soil breaker makes it possible to eliminate the presence of agglomerates that can affect the quality of the construction binder or the concrete on site. Furthermore, the powdered clay soil will provide a uniform appearance in the concrete on site.

Even more preferably, the system for preparing a construction material according to the invention comprises a screen separating gravel having a diameter of more than 10cm, preferably more than 2 cm. The system for preparing building materials may also comprise sorting means, for example of the sieve type, for separating particles having a diameter of less than 50 μm, preferably particles having a diameter of less than 20 μm. Advantageously but not limitatively, the components or particles thus separated (for example sand and/or aggregate fractions) can be reused in the formulation of building materials and extracted concrete, in particular on site.

Alternatively, not the excavated clay soil may be pretreated, but all clay soil may be used to obtain the building material. In this case, the method allows the production of concrete on site.

Furthermore, it may comprise pollution control means for treating excavated soil before it is used.

Thus, according to another aspect, the invention relates to a construction material formed by excavated clay soil. In particular, this building material can be prepared according to the preparation method according to the invention described hereinbefore. For example, the building material is directly prepared according to the preparation method according to the invention as described hereinbefore.

The building material according to the invention is characterized in that it comprises a deflocculant and excavated clay soil. It should be noted that the preparation of the building material comprises the addition of an activator. However, since this activator can react with excavated clay soil, it is not systematically found in building materials. Nevertheless, sometimes, the building material according to the invention may comprise deflocculants, activators and excavated clay soil.

The invention also relates to on-site concrete, characterised in that it comprises a deflocculant and excavated clay soil, in view of possible addition of fillers.

Alternatively, the invention also relates to a construction adhesive, characterized in that it comprises a deflocculant and excavated clay soil, in the absence of added fillers.

Advantageously, the building material according to the invention comprises a mixture of different types of clay. In particular, it may comprise a clay combination selected from:

-illite and kaolinite,

-illite and kaolinite and bentonite,

-illite and bentonite,

-kaolinite and bentonite, and-kaolinite and bentonite,

-illite and montmorillonite, or

-kaolinite, illite, smectite, bentonite, chlorite, montmorillonite, muscovite (muscovite), halloysite (halllocyte), sepiolite (sepiolite), attapulgite and vermiculite.

Furthermore, advantageously, the building material is formed by excavated clay soil, characterized in that it comprises at most 80% by weight of particles larger than 2 μm, preferably at most 60% by weight of particles larger than 2 μm. The content of particles larger than 2 μm can be measured, for example, according to the NF X31-107 standard. The excavated soil is therefore preferably subjected to a pre-treatment step, which results in a particle size concentration in the fraction having a size diameter smaller than or equal to 50 μm, preferably smaller than or equal to 20 μm.

Preferably, the building material according to the invention comprises at least 50 wt% of excavated clay soil, at least 60 wt% of excavated clay soil, at least 70 wt% of excavated clay soil, at least 80 wt% of excavated clay soil, most preferably at least 90 wt% of excavated clay soil. This is advantageously the case when the building material is a building adhesive.

Indeed, the selection of the deflocculant and activation dosage provides the advantage of being able to form a construction adhesive with a high excavated clay soil quantity without altering the mechanical properties of the resulting construction material. When the building material is site concrete, it may include at least 10 wt% of excavated clay soil, at least 15 wt% of excavated clay soil, at least 20 wt% of excavated clay soil, at least 30 wt% of excavated clay soil, at least 40 wt% of excavated clay soil, at least 50 wt% of excavated clay soil.

The deflocculant may comprise at least 0.1% by weight of the building material, at least 0.20% by weight of the building material, at least 0.25% by weight of the building material, preferably at least 0.5% by weight of the building material, more preferably at least 1% by weight of the building material, even more preferably at least 1.5% by weight of the building material, and for example at least 2% by weight of the building material. This is advantageously the case when the building material is in situ concrete.

The deflocculant may comprise at least 0.30% by weight of the building material, at least 0.5% by weight of the building material, preferably at least 1% by weight of the building material, more preferably at least 1.5% by weight of the building material, even more preferably at least 2% by weight of the building material and for example at least 2.5% by weight of the building material. This is advantageously the case when the building material is a building adhesive.

Furthermore, the deflocculant may constitute at most 20 wt.% of the building material, preferably at most 15 wt.% of the building material, and more preferably at most 10 wt.% of the building material.

In particular, the deflocculant may constitute 0.25 to 10 wt% of the construction material, preferably 0.5 to 10 wt% of the construction material, more preferably 1 to 10 wt% of the construction material, even more preferably 2 to 8 wt% of the construction binder, and for example 2 to 5 wt% of the construction binder. Accordingly, the deflocculant may preferably constitute 0.1 to 5% by weight of the building material.

In particular, the deflocculant constitutes at least 0.5 wt% of the excavated clay soil, preferably at least 1 wt% of the excavated clay soil, more preferably at least 2 wt% of the excavated clay soil, even more preferably at least 3 wt% of the excavated clay soil, and for example at least 4 wt% of the excavated clay soil. Indeed, at such deflocculant concentrations, the binder formulation according to the invention may subsequently be used in combination with an activating component (composition) to form a material with advantageous mechanical properties.

Furthermore, the deflocculant constitutes at most 20 wt% of the excavated clay soil, preferably at most 10 wt% of the excavated clay soil. Indeed, too high a concentration is not necessary to form a material with favorable mechanical properties.

In particular, the deflocculant constitutes 0.5-20 wt% of the excavated clay soil, preferably 1-10 wt% of the excavated clay soil, more preferably 3-10 wt% of the excavated clay soil and even more preferably 4-10 wt% of the excavated clay soil.

The activator is present, for example, in a content of at least 5% by weight of the building material, preferably at least 7% by weight of the building material, more preferably at least 8% by weight of the building material. This is advantageously the case when the construction material is in situ concrete.

The activator may be present, for example, in a content of at least 10 wt.% of the building material, preferably at least 15 wt.% of the building material, more preferably at least 20 wt.% of the building material, even more preferably at least 25 wt.% of the building binder, and, for example, at least 30 wt.% of the building binder.

Furthermore, the activator may comprise up to 50 wt.% of the building material, preferably up to 45 wt.% of the building material, and more preferably up to 40 wt.% of the building material. This is advantageously the case when the construction material is a construction adhesive.

The activator may also comprise up to 15 wt.% of the building material, preferably up to 12 wt.% of the building material, and more preferably up to 10 wt.% of the building material. This is advantageously the case when the construction material is in situ concrete.

In particular, the activator may constitute 3 to 12% by weight of the building material, preferably 4 to 10% by weight of the building material, more preferably 5 to 10% by weight of the building material. This is advantageously the case when the construction material is in situ concrete.

In particular, the activator may constitute 10 to 80 wt.% of the building material, preferably 15 to 80 wt.% of the building material, more preferably 20 to 80 wt.% of the building material, even more preferably 30 to 80 wt.% of the building material, and for example 40 to 60 wt.% of the building material. This is advantageously the case when the construction material is a construction adhesive.

In a particular embodiment, the building material, preferably the building binder, according to the invention comprises:

-30-80% by weight of excavated clay soil,

1% to 10% by weight of a deflocculant, and

-10% to 50% by weight of an activator.

Preferably, the building material according to the invention, preferably the building binder, comprises:

-50% -75% by weight of excavated clay soil,

1% to 10% by weight of a deflocculant, and

-15% to 50% by weight of an activator.

More preferably, the building material according to the invention, preferably the building binder, comprises:

-50% -70% by weight of excavated clay soil,

-2% to 5% by weight of a deflocculant, and

-15% to 45% by weight of an activator.

More preferably, the building material according to the invention, preferably the building binder, comprises:

-50% -60% by weight of excavated clay soil,

-2% to 5% by weight of a deflocculant, and

-25% to 45% by weight of metal oxide.

Even more preferably, the building material according to the invention, preferably the building binder, comprises:

-30-80% by weight of excavated clay soil,

-1% to 10% by weight of a deflocculant,

-10% to 40% by weight of a metal oxide, and

-2% to 15% by weight of a strong base.

Even more preferably, the building material according to the invention, preferably the building binder, comprises:

-30-80% by weight of excavated clay soil,

from 0.1% to 10% by weight of a deflocculant, and

-15-50% by weight blast furnace slag.

Even more preferably, the building material according to the invention, preferably the building binder, comprises:

-30-80% by weight of excavated clay soil,

-0.1% to 10% by weight of a deflocculant,

10% to 45% by weight of blast furnace slag, and

-5% -20% by weight of an alkaline component such as a triphosphate.

Preferably, the building material according to the invention is an in situ concrete comprising:

5-45% by weight, preferably 5-30% by weight, more preferably 10-20% by weight of the construction adhesive according to the invention;

25-45 wt.%, preferably 30-40 wt.% sand, for example from on-site soil, preferably from excavated clay soil;

35-55 wt%, preferably 40-50 wt% aggregate, for example from on-site soil, preferably from excavated clay soil; and

-preferably 2-10% by weight of water.

More preferably, the building material according to the invention is an in situ concrete comprising:

-5-20 wt% of raw clay from the excavated clay soil, preferably 5-15 wt% of raw clay from the excavated clay soil;

-0.1-3 wt% of a deflocculant;

-3-15 wt%, preferably 5-12 wt% of an activator; for example, 5% to 10% by weight of blast furnace slag;

25-45 wt.%, preferably 30-40 wt.% sand, for example from on-site soil, preferably from excavated clay soil;

35-55 wt%, preferably 40-50 wt% aggregate, for example from on-site soil, preferably from excavated clay soil; and

-preferably 2-10% by weight of water.

Sand and aggregate may be obtained from quarries. In addition, the binder may include quarry clay to supplement clay from excavated clay soil.

In addition, the site concrete may include an adjuvant (adjuvant), such as a plasticizer, a superplasticizer, a rheology retention agent, or an air entraining agent.

Furthermore, the weight ratio of water to dry matter of the construction adhesive is advantageously controlled and is preferably less than 1, more preferably substantially equal to 0.6.

Furthermore, according to another aspect, the present invention relates to a building material formed from the building adhesive according to the present invention.

Furthermore, the invention relates to a building material obtained from the preparation method according to the invention. The present invention relates to a building material obtained from the preparation process according to the invention.

The invention allows in particular to produce:

-insulating building material: produced with the construction binder according to the invention with the addition of lightweight aggregates of the "vegetable or cellular" type;

-lightweight concrete: produced with the construction binder according to the invention with the addition of a foaming agent of the aluminium powder type. This will trap air in the material and improve its insulating properties;

-a prefabricated element: producing concrete blocks or slabs from the construction adhesive according to the invention in a factory; and

-an isolation module.

As illustrated in the examples hereinafter, the present invention provides a solution based on a mixture of a raw clay matrix, a deflocculant and an activating component to provide a building material with similar mechanical properties to the standard while having a reduced carbon footprint.

Examples

Method for measuring the physicochemical properties of clay soils:

the clay soil is pre-screened to remove all components or particles greater than 20 μm in diameter. Such pretreated clay soils are particularly suitable for forming the construction binder according to the invention.

The pH was measured using 20g of pretreated clay soil mixed with 100mL of distilled water. After stirring at 150rpm (in english terminology "revolutions per minute") for 20 minutes, the suspension was filtered, and then the pH of the filtered solution was measured.

The clay content is measured in a conventional manner by the particle size method described in the NF X31-107 standard.

The properties of clays are conventionally measured by X-ray diffraction.

Generation of similarity values

As presented above, the values include a correlation between a measured value of at least one physicochemical property of the clay soil and a deflocculant and activator dosage value.

These references are formed by various clay soil samples coupled with different deflocculants and activation doses used in the process for preparing the construction binder described below.

The generation of the reference values can, for example, be carried out by experimental designs, such as for example simplex designs (plan simplexes), screen designs (plan de criblage), factorial designs (plan factors), response surface designs (plan de surface de r force), blend designs (plan de m force), or field design (plan de Taguchi).

Table 1 below presents the physicochemical properties of the different excavated soil samples, while table 2 shows an example of the experimental design used to generate the reference values.

[ Table 1]

[ Table 2]

Preparation of construction adhesive:

the construction adhesive is prepared according to the same protocol, i.e. pre-mixing between clay soil and deflocculant in predetermined amounts according to e.g. experimental plans, followed by adding water and mixing the suspension at low speed (i.e. substantially at 600 revolutions per minute) for 30 seconds, in particular when generating the reference values. Thereafter, the activator is added to the premix, which is then mixed at high speed (i.e., at about 1500 rpm) for 3 minutes.

The weight ratio of water to dry matter in the composition (also known as construction adhesive) is adjusted to a value of less than 1, more preferably substantially equal to 0.6.

The construction adhesive thus formed was then poured into a mold and allowed to cure at room temperature (i.e., at about 20 degrees celsius) for 28 days.

The mechanical properties of the construction adhesive were subsequently evaluated.

Method for measuring mechanical properties of construction adhesives:

after curing is complete, the construction adhesive is removed from the mold and the mechanical strength is measured. The mechanical strength of the construction adhesive means its compressive strength, measured according to the NF EN 196-1 standard.

The results of the measurements performed for the experiments described in table 2 are presented in table 3 below.

[ Table 3]

These results show that the properties of the formed binder will be different and in particular its mechanical strength, depending on the amount of activator and deflocculant used.

Furthermore, it shows that the presence of a deflocculant allows to obtain mechanical strengths higher than 30 MPa.

Selection of the composition of the construction adhesive:

after preparing the reference values and, if necessary, the calculation algorithm, a method for selecting the appropriate deflocculant and activation dosage for a given excavated clay soil can be implemented.

First, a sample of the excavated clay soil is sieved, so that all components or particles with a diameter greater than 20 μm are removed.

The pretreated mined clay sample was then analyzed for physicochemical properties as described previously.

The obtained values are then transmitted to a computer device configured to implement the method according to the invention.

The latter in turn generates values for the deflocculant and activator dosage that form the construction adhesive when coupled with a predetermined amount of dredged soil.

Formation of the construction adhesive according to the invention

The excavated clay soil is then sieved to remove any components or particles having a diameter greater than 2cm, and then a predetermined amount of the pre-treated excavated clay soil is mixed with selected deflocculant and activator amounts simultaneously or sequentially.

The construction adhesive or site concrete formed according to the present invention has a compressive strength comparable to that obtained by concrete formed with portland cement. The invention therefore allows the selection of the right composition, which makes it possible to form from excavated clay soils a low-carbon construction binder having sufficient mechanical properties to make it a construction material that meets most of the needs of the field.