CONSTRUCTION BINDER AND ASSOCIATED CONSTRUCTION MATERIAL

Abstract

The invention relates in particular to a construction binder comprising at least 5% by weight of recycled concrete fines, at most 40% by weight of activator(s), at least 5% raw clay matrix(es), and at least one deflocculating polymer. The invention also relates to a method for preparing such a construction binder and to construction materials based on this binder. Figure to be published with the abstract: 1

Description

Title of the invention: CONSTRUCTION BINDER AND ASSOCIATED CONSTRUCTION MATERIAL Technical field

[0001] The invention relates to the field of construction and more particularly to that of low-carbon construction materials. In particular, it relates to a construction binder comprising a raw clay matrix, recycled concrete fines and a deflocculant. Furthermore, the invention relates to a construction material produced from a construction binder according to the invention. Prior art

[0002] Below we describe the known prior art from which the invention was developed.

[0003] Cement is the second most consumed resource in the world, with more than 4 billion tons produced each year worldwide. This consumption is constantly increasing, driven by the growing demand for housing and infrastructure. Cement is particularly used for the manufacture of masonry elements that rely on cementitious materials as binders. Due to the constant development of new infrastructure in most countries of the world, there is a constant demand for the supply of construction binders, more specifically raw materials for the formation of Portland cement. However, the production and use of Portland cement is associated with a high environmental footprint. The cement used in the construction field is generally Portland cement. It is a hydraulic binder which, when mixed with water, hardens and sets.After hardening, cement retains its strength and stability even when exposed to water. There is a wide variety of cements used worldwide. However, all conventional cements contain clinker at a percentage ranging from 5% for some blast furnace cements to a minimum of 95% for Portland cement, which is the most widely used cement in the world today. Clinker is the result of firing a mixture of approximately 80% limestone and 20% aluminosilicates (such as clays). This firing, clinkerization, is generally carried out at a temperature of over 1200°C, so such a cement preparation process involves high energy consumption. In addition, the chemical conversion of limestone into lime also releases carbon dioxide. As a result, the cement industry generates approximately 8% of global CO2 emissions.

[0004] Indeed, it is estimated that the manufacture of a Portland-type construction binder generates on average 0.8 kg of CO2 per kg of Portland cement clinker produced. Different solutions have therefore been developed to try to replace at least partially certain components of the construction binders used for the formation of Portland-type cements. These solutions are mainly aimed at reducing the carbon footprint.

[0005] New construction binders and materials containing a significant quantity of recycled concrete in the form of aggregate or filler are being developed and make it possible to achieve significantly reduced carbon footprints.

[0006] Recycled concrete-based materials, particularly recycled concrete aggregates (RCA), are among the new materials for reducing the carbon footprint of construction materials. Along with recycled concrete fines (RCF), they present a sustainable alternative to natural aggregates in construction applications. The use of RCA and RCF conserves resources and reduces waste disposal, providing a more environmentally friendly solution. In the current state of the art, RCA has been successfully used as a base material in road construction, as a fill material for embankments and fills, paving, landscaping, and as a replacement for natural aggregates in new concrete production.RCFs have been used to partially replace natural sand in mortar production. The implementation of RCAs and RCFs in construction applications helps meet the growing demand for sustainable practices in the industry, while maintaining performance requirements.

[0007] More recently, recycled concrete fines have been proposed as construction binder elements. However, the use of recycled concrete fines (RCF) in concrete mixes has certain limitations. Indeed, they have a significant impact on the workability and water demand of cements, which can lead to a reduction in performance over the long term.

[0008] In order to promote their democratization and their valorization, these low-carbon solutions must be able to present a high mechanical resistance at an early age so that industrial processes can substitute Portland cement with these low-carbon solutions without consequences.

[0009] Thus, there is a need for new construction materials based on recycled concrete fines having improved mechanical properties such as high mechanical compressive strength at early age (1 day) while allowing high mechanical compressive strength at 28 days, and minimized shrinkage at 90 days. Summary of the invention

[0010] The invention aims to overcome these drawbacks. The following presents a simplified summary of selected aspects, embodiments and examples of the present invention for the purpose of providing a basic understanding of the invention. However, the summary of the invention does not constitute an exhaustive overview of all aspects, embodiments and examples of the invention. The sole purpose of the summary is to present selected aspects, embodiments and examples of the invention in a concise form as an introduction to the more detailed description of the aspects, embodiments and examples of the invention which follow the summary.

[0011] The invention relates in particular to a construction binder comprising at least 5% by weight of recycled concrete fines, at most 40% by weight of activator(s), at least 5% of raw clay matrix(es), and at least one deflocculating polymer.

[0012] The applicant has developed a new construction binder combining raw clay matrix with recycled concrete fines. This new binder, using recycled concrete fines in combination with a raw clay matrix, makes it possible to obtain a material having a high early mechanical strength while achieving mechanical strengths at 28 days consistent with the majority of use cases in the construction industry. Compressive strength at an early age also minimizes the risk of loss of structural integrity during the first phase of construction. The present invention, as illustrated in the examples, makes it possible, in the presence of raw clay matrix and a deflocculating polymer, to maintain mechanical performance even with significant quantities of fines and fewer activators.

[0013] According to other optional characteristics of the construction binder, the latter may optionally include one or more of the following characteristics, alone or in combination: - it also contains at least 5% by weight of precursor. The presence of precursor makes it possible to improve the mechanical resistance at 28 days in combination with the raw clay matrix and the recycled concrete fines. - the precursor is selected from: slags such as blast furnace slags, steelworks slags, cupola slags; fly ash, natural pozzolans, silica fumes, micronized limestone fillers, micronized siliceous fillers such as glass powder, siliceous fillers, synthetic vaterite, diatomaceous earth, ground slag or combinations thereof. - the precursor is selected from: blast furnace slag, micronized limestone filler; vaterite such as micrometric vaterite or nanometric; or their combinations. These precursors are particularly suitable in combination with the raw clay matrix and recycled concrete fines. the recycled concrete fines have a D50 less than or equal to 1000 pm, preferably less than or equal to 750 pm. Such a particle size makes it possible to improve the performance of the construction binders according to the invention. the recycled concrete fines have a pozzolanic activity greater than or equal to 30% as measured according to method A of the ASTM C1897 standard. Preferably, the recycled concrete fines have a pozzolanic activity greater than or equal to 40%, more preferably greater than or equal to 50% and more preferably greater than or equal to 60%; according to method A of the ASTM C1897 standard. The recycled concrete fines have an oxide composition such that CaO represents at least 20% by weight of the recycled concrete fines. This makes it possible to improve the mechanical resistance at 28 days in combination with the raw clay matrix and the recycled concrete fines. recycled concrete fines have a composition such that 3CaOSiO2 represents at least 5% by weight of the recycled concrete fines. recycled concrete fines have a composition such that 2CaOSiO2 represents at least 5% by weight of the recycled concrete fines. It contains at least 10% by weight of raw clay matrix(es) relative to the dry weight of construction binder. This improves the performance of the construction binder. It comprises at least 15% by weight of activator(s), preferably at least 15% by weight of CEM I as activator; relative to the dry weight of construction binder. It contains at most 60% by weight of recycled concrete fines; relative to the dry weight of the construction binder. the raw clay matrix and the recycled concrete fines are present in such a quantity that the mass ratio between the raw clay matrix and the recycled concrete fines is between 0.1 and 0.75; inclusive. This improves the performance of the construction binder. the D50 of the raw clay matrix is less than 200 pm while the D50 of the recycled concrete fines is greater than 200 pm; preferably, the D50 of the raw clay matrix is less than 150 pm and the D50 of the recycled concrete fines is greater than 250 pm; the D50 is preferably measured according to the ISO 13320:2020 standard or according to the NF EN 933-1 standard, preferably according to the NF EN 933-1 standard. This improves the performance of the construction binder. - the D50 of the raw clay matrix is greater than 200 pm and the D50 of the recycled concrete fines is less than 200 pm; preferably the D50 of the raw clay matrix is greater than 250 pm and the D50 of the recycled concrete fines is less than 150 pm; the D50 is preferably measured according to the ISO 13320:2020 standard or according to the NF EN 933-1 standard, preferably according to the NF EN 933-1 standard. This improves the performance of the construction binder.

[0014] According to another object, the invention relates to a method for preparing a construction binder according to the invention. In particular, the method may comprise a step of mixing at least part of the constituents of the construction binder and then a step of adding water.

[0015] According to another object, the invention relates to a construction material formed from a construction binder according to the invention and further from aggregates. Brief description of the drawings

[0016] Other characteristics and advantages of the invention will be better understood on reading the description which follows and with reference to the attached drawing, given for illustrative purposes and in no way limiting.

[0017] [Fig.l] [Fig.l] represents a schematic illustration of a manufacturing method according to an embodiment of the present invention. The steps outlined in dotted lines are optional.

[0018] The figure does not necessarily respect the scale, in particular in thickness, and this is for illustration purposes.

[0019] Aspects of the present invention are described with reference to flowcharts and / or block diagrams of methods according to embodiments of the invention. In the figures, the flowcharts and block diagrams illustrate the architecture, functionality and operation of possible implementations of systems and methods according to various embodiments of the present invention. In this regard, each block in the flowcharts or block diagrams may represent a system, a device, a module implementing the specified logical function(s). In some implementations, the functions associated with the blocks may appear in a different order than indicated in the figures. For example, two blocks shown in succession may, in fact, be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order, depending on the functionality involved.Each block of the block diagrams and / or flowchart, and combinations of blocks in the block diagrams and / or . the organizational chart, can be implemented by special hardware systems that perform the specified functions or acts. Description of the embodiments

[0020] Below, we describe a summary of the invention and the associated vocabulary, before presenting the disadvantages of the prior art, and then finally showing in more detail how the invention overcomes them.

[0021] In the remainder of the description, the expression "raw earth" may correspond to a granular mineral material, for example, derived from sedimentary rock or sedimentary deposits. Raw earth has different names depending on its composition or its origins. Raw earth may, for example, correspond to clayey, sandy clay, clayey-loamy, clayey-loamy, fine clayey-loamy, sandy-loamy, loamy, fine clayey-loamy, fine loamy, very fine loamy, sandy-loamy, sandy-loamy, and sandy soils. Raw earth may also correspond to waste rock (from discovery or production), exposed clays, excavated earth, such as excavated clayey earth, clayey sands from treatment plants, sludge or even sediments.

[0022] The term "binder" within the meaning of the invention can be understood as a formulation making it possible to ensure the agglomeration of materials between them, in particular during the setting and then hardening of a construction material. Thus, it makes it possible in particular to ensure the agglomeration of sand and other constituents of the construction material with the constituents of the binder. The binder according to the invention is in particular a hydraulic binder, that is to say that hardening takes place on contact with water.

[0023] The expression "clay matrix", within the meaning of the invention, may correspond to one or more rock materials based on hydrated silicates or aluminosilicates of lamellar structure, said clay matrix being composed of fine particles generally originating from the alteration of silicates with a three-dimensional framework, such as feldspars. A clay matrix may thus comprise a mixture of such rock materials which may, for example, consist of kaolinite, illite, smectite, bentonite, chlorite, vermiculite, or mixtures thereof. In addition, a clay matrix may comprise silts.

[0024] For the purposes of the invention, the expression "raw clay matrix" may correspond to a clay matrix that has not undergone a calcination step. For example, this corresponds to a clay matrix that has not undergone a temperature rise greater than 300°C, preferably greater than 200°C and more preferably a temperature greater than 150°C. Indeed, the raw clay matrix may undergo a drying step by heating requiring a temperature rise generally substantially equal to or less than 150°C but no calcination step. A matrix raw clay may preferably comprise a mixture of rock materials which may for example comprise kaolinite, illite, smectite, micas such as muscovite, bentonite, chlorite, vermiculite, or mixtures thereof, as well as silts.

[0025] For the purposes of the invention, a “deflocculating agent”, “deflocculant”, “deflocculating polymer” or “defloculation agent” may correspond to a compound capable of dissociating aggregates and colloids, particularly in aqueous suspension. Deflocculating agents have, for example, been used in the context of drilling or oil extraction to make clay more fluid and facilitate extraction or drilling.

[0026] The term "D50" corresponds to the median diameter for which 50% (by volume or by mass, preferably by mass) of the grains, particles, aggregates or sediments have a size smaller than a given diameter. For example, a sieving and sedimentometry analysis method indicates a D50 = 5.8 mm, then 50% of the particles in the sample (by volume or by mass, preferably by mass) are greater than 5.8 mm. D50 is generally used to represent the particle size of a group of particles. D50 is preferably measured according to ASTM D422-63 or ASTM D6913-04(2009) or in particular for fine particles ISO 13320:2020 (eg D10 or <65 pm).

[0027] The expressions "granulometric property" or "granulometric profile" or "particle size distribution" may correspond to values of parameters relating to the particle size distribution, for example in the raw clay matrix or in raw earths. There are many parameters relating to the particle size distribution such as D50, D10, D90.

[0028] In the remainder of the description, the term "% by weight" in relation to the binder, the mixture, or in relation to the compressed earth brick, must be understood as being a proportion relative to the dry weight. The dry weight corresponds to the weight before the addition of water, for example, necessary for the formation of the compressed earth brick. When the values of % by weight are given in the form of intervals, the limits are included.

[0029] The term "sand" can refer to particles, originating from the disintegration of rocks, whose size is between 0.063 mm and 2 mm.

[0030] The term "silt" can refer to particles whose grain size is intermediate between clays and sands (between approximately 2 and 63 micrometers).

[0031] The term "micronized" may refer to a component of the construction binder which has undergone an operation aimed at transforming it into a set of micrometric particles, i.e. having a D50 of between 1 pm and 200 pm.

[0032] The term "nanometric" may refer to a component of the construction binder having a D50 between 1 nm and 200 nm.

[0033] The expression "demolition concrete" according to the meaning of the invention, can refer to concrete resulting from a demolition process where concrete structures are completely destroyed without discrimination of the components, often resulting in a heterogeneous mixture of materials.

[0034] The expression "deconstruction concrete" according to the meaning of the invention may refer to concrete resulting from a selective demolition process, where certain parts of the structure are dismantled in a targeted manner, allowing more efficient sorting of materials for recycling.

[0035] The term “substantially equal” within the meaning of the invention corresponds to a value varying by less than 20% compared to the compared value, preferably by less than 10%, even more preferably by less than 5%.

[0036] In view of growing environmental challenges and the significant impact of the construction industry on natural resources, the urgency to develop sustainable alternatives is more pressing than ever. One of the major problems lies in the massive use of concrete, a ubiquitous material in construction, which generates significant CO2 emissions and a considerable consumption of natural resources. This reality raises critical questions about the long-term viability of our current construction practices. In this context, the development of recycled concrete appears as a promising solution. Not only does this innovation have the potential to reduce the carbon footprint and dependence on raw materials, but it also offers a way to recover construction waste.Thus, the construction sector must evolve to optimize its productivity while responding to societal and environmental challenges.

[0037] Faced with this observation, the applicant has developed a new solution making it possible to obtain a low-carbon construction binder, at low cost while having good mechanical properties such as low shrinkage and high compressive strength at early age and at 28 days. As detailed below, the solution developed is based on the preparation of a binder comprising a mixture of recycled concrete fines and a raw clay matrix in combination with at least one activator and a deflocculating polymer in suitable proportions. Thus, the recycled concrete fines are no longer used as aggregates in combination with cement but as constituents of the binder in combination with raw clay.

[0038] Thus, according to a first aspect, the invention relates to a construction binder. A construction binder according to the present invention comprises recycled concrete fines, at least one activator, at least one raw clay matrix, and at least one deflocculating polymer.

[0039] In addition, the construction binder may comprise a precursor. RECYCLED CONCRETE FINES

[0040] A construction binder according to the invention comprises recycled concrete fines. The use of recycled concrete fines makes it possible to limit the environmental impact of a construction material formed from a construction binder according to the invention. Indeed, the use of recycled concrete fines is not at the filler level but at the binder level makes it possible to reduce the use of activators which often have a high environmental footprint. Thus, the use of concrete fines in a construction binder makes it possible to reduce carbon emissions. In addition, the use of recycled concrete fines makes it possible to propose a new way of recovering elements considered as industrial waste.

[0041] The recycled concrete fines according to the present invention can be selected from various mineral materials from the construction and demolition industries. These mineral materials are preferably derived from elements considered to be waste generated during the production of concrete, from new construction remains, from renovation waste, from demolition concrete and / or, preferably, from deconstruction concrete. For example, the recycled concrete fines from deconstruction concrete have the advantage of having been sorted. Thus, generally these fines have, for example, fewer elements considered to be impurities.

[0042] The recycled concrete fines according to the invention may comprise an oxide composition such as CaO, 3CaOSiO2 and / or 2CaOSiO2.

[0043] Preferably, the recycled concrete fines may have an oxide composition such that CaO represents at least 5% by weight of concrete fines, preferably at least 10%, more preferably at least 15% and even more preferably at least 20% by weight of the recycled concrete fines. The CaO content can be measured according to the NF EN 451-1 standard of June 2017 applied to fly ash. The CaO content can also be measured by X-ray fluorescence, for example according to the ISO 29581-2:2010 standard.

[0044] The recycled concrete fines may have a composition such that 3CaOSiO2 represents at least 1% by weight of concrete fines, preferably at least 2%, more preferably at least 4% and even more preferably at least 5% by weight of the recycled concrete fines. The 3CaOSiO2 content may also be measured by X-ray fluorescence, for example according to ISO 29581-2:2010.

[0045] The recycled concrete fines may have a composition such that 2CaOSiO2 represents at least 1% by weight of concrete fines, preferably at least 2%, more preferably at least 4% and even more preferably at least 5% by weight. weight of recycled concrete fines. The 3CaOSiO2 content can also be measured by X-ray fluorescence, for example, according to ISO 29581-2:2010.

[0046] A construction binder according to the invention may comprise at least 5% by weight of recycled concrete fines relative to the dry weight of construction binder, preferably at least 10% by weight of recycled concrete fines relative to the dry weight of construction binder, preferably at least 15% by weight of recycled concrete fines relative to the dry weight of construction binder, and even more preferably at least 17% by weight of recycled concrete fines relative to the dry weight of the construction binder.

[0047] A construction binder according to the invention may comprise at most 75% by weight of recycled concrete fines relative to the dry weight of the construction binder, preferably at most 50% by weight of recycled concrete fines relative to the dry weight of the construction binder, even more preferably at most 40% by weight of recycled concrete fines relative to the dry weight of the construction binder, even more preferably at most 30% by weight of recycled concrete fines relative to the dry weight of the construction binder.

[0048] Advantageously, a construction binder according to the invention may comprise from 5% to 75% by weight of recycled concrete fines relative to the dry weight of the construction binder, preferably from 10% to 50% by weight of recycled concrete fines relative to the dry weight of the construction binder, even more preferably from 15% to 40% by weight of recycled concrete fines relative to the dry weight of the construction binder, even more preferably from 17% to 30% by weight of recycled concrete fines relative to the dry weight of the construction binder.

[0049] At such proportions, the construction material produced from such a binder exhibits shrinkage as well as mechanical strengths at young age and at 28 days equivalent to a commonly used cement.

[0050] The recycled concrete fines making up the construction binder according to the present invention may have a D50 less than or equal to 1 mm, preferably less than or equal to 750 pm; the D50 preferably being measured according to the ISO 13320:2020 standard or according to the NF EN 933-1 standard.

[0051] Advantageously, the D50 of the recycled concrete fines is selected according to the D50 of the raw clay matrix.

[0052] Preferably, when the D50 of the raw clay matrix is less than 200 pm then the D50 of the recycled concrete fines is greater than 200 pm. In particular, when the D50 of the raw clay matrix is less than 150 pm then the D50 of the recycled concrete fines is greater than 250 pm. More preferably, when the D50 of the raw clay matrix is less than 100 pm then the D50 of the concrete fines recycled is greater than 300 pm. The D50 is preferably measured according to the ISO 13320:2020 standard or according to the NF EN 933-1 standard.

[0053] Conversely, when the D50 of the raw clay matrix is greater than 200 pm then the D50 of the recycled concrete fines is less than 200 pm. In particular, when the D50 of the raw clay matrix is greater than 250 pm then the D50 of the recycled concrete fines is less than 150 pm. More preferably, when the D50 of the raw clay matrix is greater than 300 pm then the D50 of the recycled concrete fines is less than 100 pm. The D50 is preferably measured according to the ISO 13320:2020 standard or according to the NF EN 933-1 standard. RAW CLAY MATRIX(ES)

[0054] As seen previously, a construction binder according to the invention comprises at least one raw clay matrix.

[0055] The raw clay matrix may for example comprise at least one mineral species selected from: Illite, Kaolinite, Smectite, Vermiculite, Chlorite, Montmorillonites, Muscovite, Halloysite, Sepiolite, and Palygorskite.

[0056] Preferably, the raw clay matrix may comprise at least two types of clays selected from: Illite, Kaolinite, Smectite, Vermiculite, Chlorite, Montmorillonites, Muscovite, Halloysite, Sepiolite, Interstratified, Pyrophyllite, talcs, Serpentines and Palygorskite. This includes so-called interstratified clays which are complex combinations of several clays. Even more preferably, the raw clay matrix may comprise at least one mineral species selected from: Kaolinite, Illite, Smectite, Palygorskite, Sepiolite, Chlorite, Montmorillonites, and Vermiculite.

[0057] Table 1 below presents the chemical characteristics of these mineral species. [Tables 1] Matrix Clayey C rue Type of clay Composition Illite (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)] Smectite (Na,Ca)o,3(Al,Mg)2Si4010(OH)2, n H2O Kaolinite Al2Si2O5(OH)4 Vermiculite (Mg,Ca)o,7(Mg,Fe,Al)6(Al,Si)8022(OH)4nH20 Chlorite (Fe,Mg,Al)6(Si,Al)4O10(OH)8 Muscovite KAl2(AlSi3O10) (OH,F)2 Halloysite Al2Si2O5(OH)4 Sepiolite Mg4Si6O15(OH)2, n H2O

[0058]

[0059]

[0060]

[0061]

[0062] Palygorskite (Mg,Al,Fe3+)5[Si8O20](OH)2 (OH2)4n H2O According to a preferred embodiment, a binder for construction material according to the invention may comprise at least two different types of clays and may comprise smectite (Smectite, Bentonite, Montmorillonite), kaolinite, and / or illite. The type of clay can be determined by methods known to the person skilled in the art, for example after specific preparation of the samples using the so-called oriented blade method (see Thiry et al. - 2013 - Technique for preparing clay minerals for analysis by X-ray diffraction and introduction to the interpretation of diagrams). In particular, it will be possible to use X-ray diffractometry. For example, the following conditions may be used: - Equipment: Diffractometer, for example a BRUKER D8 ADVANCE (Bragg-Brentano geometry); for example with the following settings: Copper tube (X Kal ~ 1.54 Â) Generator power: 40 kV, 40 mA; Primary optics: fixed slit 0.16°; Soller slit 2.5°; Secondary optics: Soller slit 2.5°; LynXeye XE-T detector - Acquisition parameters: Scan from 4 to 90°20; Scan speed of 0.03°20 / second, Counting time: 480 seconds per step; Rotating sample. A construction binder according to the invention may comprise at least 5% by weight of raw clay matrix relative to the dry weight of construction binder, preferably at least 10% by weight of raw clay matrix, more preferably at least 15% by weight of raw clay matrix, even more preferably at least 20% by weight of raw clay matrix relative to the dry weight of construction binder. A construction binder may comprise at most 50% by weight of raw clay matrix relative to the dry weight of construction binder, preferably at most 40% by weight of raw clay matrix relative to the dry weight of construction binder, more preferably at most 30% by weight of raw clay matrix relative to the dry weight of construction binder, even more preferably at most 20% by weight of raw clay matrix relative to the dry weight of construction binder. A construction binder according to the invention may comprise from 5% to 50% by weight of raw clay matrix relative to the dry weight of construction binder, preferably from 5% to 40% by weight of raw clay matrix relative to the dry weight of construction binder, preferably from 5% to 30% by weight of raw clay matrix relative to the dry weight of construction binder and even more preferably from 10% to 30% by weight of raw clay matrix relative to the dry weight of construction binder.

[0063] Preferably, the raw clay matrix and the recycled concrete fines are present in such a quantity in the construction binder that the mass ratio by weight between the raw clay matrix and the recycled concrete fines is between 0.1 and 0.75, inclusive. More preferably, the raw clay matrix and the recycled concrete fines are present in such a quantity in the construction binder that the mass ratio by weight between the raw clay matrix and the recycled concrete fines is between 0.3 and 0.75, inclusive.

[0064] Advantageously, the raw clay matrix may have a D50 of less than or equal to 200 qm, preferably less than or equal to 150 qm, more preferably less than or equal to 100 qm, even more preferably less than or equal to 80 qm.

[0065] As described above, the D50 of the raw clay matrix can be a function of the D50 of the recycled concrete fines.

[0066] Furthermore, a construction binder may comprise at least two raw clays having different particle size profiles. For example, one of the raw clay matrices used, preferably a ground raw clay matrix, has a D50 of less than 500 qm, preferably a D50 of less than 200 qm, preferably less than or equal to 150 qm, more preferably less than or equal to 100 qm, even more preferably less than or equal to 80 qm. Furthermore, one of the clay matrices used has a D50 of greater than 500 qm, preferably greater than or equal to 750 qm, more preferably greater than or equal to 1 mm, even more preferably greater than or equal to 1.5 mm.

[0067] In particular, one of the raw clay matrices used has a raw clay fraction having a D50 of less than 200 qm, preferably less than or equal to 150 qm, more preferably less than or equal to 100 qm, even more preferably less than or equal to 80 qm. In addition, one of the raw clay matrices used has a raw clay fraction having a D50 of greater than 500 qm, preferably greater than or equal to 750 qm, more preferably greater than or equal to 1 mm, even more preferably greater than or equal to 1.5 mm. ACTIVATOR(S)

[0068] A construction binder according to the invention comprises at least one activator. Preferably, the at least one activator may be selected from: clinker, CEM I, lime, silicates such as sodium silicate, carbonates such as sodium carbonate or combinations thereof. Advantageously, the activator comprises clinkers.

[0069] Furthermore, a construction binder according to the invention may comprise at least 5% by weight of activator(s) relative to the dry weight of the construction binder, preferably at least 10%, more preferably at least 15%, and even more preferably more preferably at least 20% by weight of activator(s) relative to the dry weight of the construction binder.

[0070] A construction binder according to the invention may comprise at most 55% by weight of activator(s) relative to the dry weight of the construction binder, preferably at most 50%, more preferably at most 45%, and even more preferably at most 40% by weight of activator(s) relative to the dry weight of the construction binder.

[0071] A construction binder according to the invention may comprise from 5% to 55% by weight of activator(s) relative to the dry weight of the construction binder, preferably from 10% to 50%, more preferably from 15% to 45%, and even more preferably from 20% to 40% by weight of activator(s) relative to the dry weight of the construction binder.

[0072] Preferably, the construction binder comprises at least 20% by weight of CEM I as activator relative to the dry weight of construction binder. PRECURSOR(S)

[0073] Recycled concrete fines may be considered by some to be a precursor. A construction binder according to the present invention may advantageously further comprise at least one precursor which is not recycled concrete fines. Preferably, the construction binder may comprise at least two precursors.

[0074] Thus, a construction binder according to the invention may comprise at least one precursor, said precursor being able to be selected from: slags such as blast furnace slags, steelworks slags, cupola slags; fly ash, natural pozzolans, silica fumes, micronized limestone fillers, micronized siliceous fillers such as glass powder, siliceous fillers, synthetic vaterite, diatomaceous earths, ground slag or combinations thereof.

[0075] Advantageously, the precursor may be selected from: blast furnace slag, micronized limestone filler; vaterite such as micrometric or nanometric vaterite; or combinations thereof.

[0076] In the invention, when the precursor is present, it may be present at a content of at least 1% by weight of the construction binder, preferably at a content of at least 10% by weight of the construction binder, even more preferably at a content of at least 15% by weight of the construction binder.

[0077] Furthermore, preferably, the construction binder according to the invention comprises at most 25% by weight of precursor, more preferably at most 20% by weight of precursor.

[0078] Thus, in particular, a construction binder according to the invention may comprise between 1% and 25% by weight of precursor, preferably between 10% and 25% by weight of precursor, more preferably between 10% and 20% by weight of precursor. DEFLOCCULANT

[0079] As mentioned, a construction binder according to the present invention comprises at least one organic deflocculant, preferably it comprises a deflocculant polymer. The presence of one or more deflocculant(s) can improve the performance of the material formed from the construction binder.

[0080] Many compounds can act as deflocculation agents and many are generally known to those skilled in the art.

[0081] The presence of one or more deflocculation agent(s) may improve the performance of the material formed from the construction binder.

[0082] In the context of the invention, a construction binder may comprise an organic deflocculation agent, advantageously a deflocculating polymer. According to the present invention, an organic deflocculation agent comprises at least one carbon atom and preferably at least one carbon-oxygen bond.

[0083] The deflocculating polymer may be a non-ionic surfactant such as a polyoxyethylene ether. The polyoxyethylene ether may for example be selected from: a lauryl poly(oxyethylene) ether.

[0084] The deflocculating polymer may also be an anionic agent such as an anionic surfactant. In particular, the anionic agent may be selected from: alkylaryl sulfonates, amino alcohols, carbonates, silicates, fatty acids, humates (e.g. sodium humates), carboxylic acids, lignosulfonates (e.g. sodium lignosulfonates), polyacrylates, phosphates or polyphosphates such as sodium hexametaphosphate, sodium tripolyphosphate, sodium orthophosphate, carboxymethylcelluloses and mixtures thereof.

[0085] The deflocculating polymer may also be a polyacrylate. It may then be selected, for example, from sodium polyacrylate and ammonium polyacrylate.

[0086] The deflocculating polymer may also be an amine selected for example from: 2-amino-2-methyl-l-propanol; mono-, di or tri ethanolamine, isopropanolamines (l-Amino-2-propanol, diisopropanolamine, triisopropanolamine) and N-alkyl ethanolamines.

[0087] Preferably, the deflocculating polymer is selected from: a lignosulphonate (eg sodium lignosulphonate), a polyacrylate, a humate and their mixtures.

[0088] Preferably, the deflocculating polymer is selected from: a lignosulphonate (eg sodium lignosulphonate), a polyacrylate, a humate, a polycarboxylate such as an ether polycarboxylate, and mixtures thereof.

[0089] More preferably, the deflocculating polymer comprises a humate, a lignosulphonate and / or a polyacrylate.

[0090] The deflocculation agent may also be a silicate such as sodium silicate, sodium metasilicate or sodium trisilicate.

[0091] Alternatively, the deflocculation agent may be a mixture of compounds, such as a mixture comprising at least two compounds selected from: non-ionic surfactant, anionic agent, polyacrylate, amine and organophosphorus compound.

[0092] However, the invention cannot be limited to the deflocculating agents mentioned above; any type of deflocculating agent known to those skilled in the art can be used instead of the said deflocculating agents mentioned above.

[0093] The deflocculation agent is preferably in the form of a salt. The deflocculation agents usable according to the present invention may take a solid form or a liquid form.

[0094] In particular, the deflocculating agent, preferably the deflocculating polymer, represents at least 0.05% by weight of the construction binder, preferably at least 0.1% by weight of the construction binder, preferably at least 0.25% by weight of the construction binder, more preferably at least 0.5% by weight of the construction binder, more preferably at least 0.5% by weight of the construction binder, even more preferably at least 0.8% by weight of the construction binder and for example at least 1% by weight of the construction binder.

[0095] Furthermore, the deflocculating agent, preferably the deflocculating polymer, represents at most 5% by weight of the construction binder, preferably at most 4% by weight of the construction binder, more preferably at most 3% by weight of the construction binder and even more preferably at most 2% by weight of the construction binder. Indeed, too high a concentration is not necessary to form a material with advantageous mechanical properties.

[0096] In particular, the deflocculating agent, preferably the deflocculating polymer, represents between 0.05% and 5% by weight of the construction binder, preferably between 0.1% and 4% by weight of the construction binder, more preferably between 0.25% and 3% by weight of the construction binder, even more preferably between 0.5% and 2% by weight of the construction binder and even more preferably between 0.8% and 2% by weight of the construction binder and even more preferably between 0.9% and 2% by weight of the construction binder.

[0097] In particular, the construction binder according to the invention comprises: from 5% to 60% by weight of recycled concrete fines, from 15% to 40% by weight of activator(s), from 5% to 40% by weight of raw clay matrix(s), from 0% to 30% by weight of precursor, and from 0.1% to 4% by weight of a deflocculating polymer. In particular, the construction binder according to the invention comprises: - from 10% to 60% by weight of recycled concrete fines, - from 15% to 40% by weight of activator(s), - from 5% to 30% by weight of raw clay matrix(es), - from 10% to 30% by weight of precursor, and - from 0.1% to 4% by weight of a deflocculating polymer. In particular, the construction binder according to the invention comprises: - from 15% to 60% by weight of recycled concrete fines, - from 15% to 40% by weight of activator(s), - from 10% to 25% by weight of raw clay matrix(es), - from 10% to 25% by weight of precursor, and - from 0.1% to 4% by weight of a deflocculating polymer. In the three compositions described above the terminals are included.

[0098] According to a second aspect, the invention relates to a method 100 for preparing a construction binder. Preferably, the preparation method 100 makes it possible to prepare a binder according to the present invention. As illustrated in [Fig.l], a preparation method 100 according to the invention comprises a step 130 of mixing at least a portion of the constituents of the construction binder.

[0099] A method 100 for preparing a construction binder according to the invention may further comprise: a step 110 of analyzing the recycled concrete fines, a step 120 of treating the recycled concrete fines.

[0100] Several embodiments, preferred or not, have been described previously in relation to the construction binder according to the invention. Thus, a method of preparing 100 the construction binder according to the invention may comprise, alone or in combination, each of the characteristics described above in relation to a construction binder according to the invention and its constituents.

[0101] A method 100 for preparing a binder according to the invention may comprise a step 110 of analyzing the recycled concrete fines. Indeed, the recycled concrete fines generally contain impurities which can modify their properties and, in doing so, lead to a construction material having undesired properties.

[0102] An analysis step 110 can therefore make it possible to evaluate the quantity and / or the nature of the impurities present in the recycled concrete fines. In addition, evaluating the quality of the recycled concrete fines can also make it possible to select the different constituents of the construction binder according to their nature, making the method 100 according to the invention more flexible.

[0103] Furthermore, an analysis step 110 can be implemented by an analyzer. An analyzer can be selected from: a spectrometer (infrared, NMR, Raman, X-ray fluorescence, mass), an X-ray diffractometer, a microscope (transmission, scanning), and / or other optical sensors.

[0104] A method 100 for preparing a construction binder according to the invention may comprise a step 120 of treating the recycled concrete fines. The step 120 of treating the recycled concrete fines may make it possible to prepare said fines to be mixed with other constituents of the construction binder. The treatment step may comprise screening and / or grinding.

[0105] Screening of recycled concrete fines may be carried out within a screen. For example, screening may remove unwanted particles present in the recycled concrete fines. The screen may be selected from a rotary drum screen, a vibrating screen, a hydrocyclone or an air separator.

[0106] Grinding makes it possible to control the D50 of the recycled concrete fines. Preferably, during the formation of the binder, the recycled concrete fines may have a D50 less than or equal to 1000 pm, preferably less than or equal to 750 pm, more preferably less than or equal to 600 pm, even more preferably less than or equal to 500 pm. The particle size is preferably measured according to the ISO 13320:2020 standard or according to the NF EN 933-1 standard.

[0107] Advantageously, the recycled concrete fines are ground by a grinder. A grinder can be selected from: a hammer mill, a ball mill, a blade mill, a bucket mill, a lump crusher, a crusher mill or even a rod mill.

[0108] In a particular embodiment, the grinding may comprise the grinding of recycled concrete fines according to two distinct D50s.

[0109] Advantageously, as described above, the raw clay matrix is also ground, for example according to two separate D50s.

[0110] A method for preparing 100 a construction binder according to the invention comprises a step 130 of mixing at least a portion of the constituents of the construction binder. Advantageously, the step 130 of mixing at least a portion of the constituents of the construction binder is carried out dry. Preferably, the mixing step 130 may comprise the dry mixing of all the constituents of the construction binder.

[0111] The step 130 of mixing the constituents of the construction binder comprises the mixture of at least recycled concrete fines, raw clay matrix, an activator, a precursor and a deflocculating polymer. This mixing can be carried out by a mixer or a blender. The mixer can be, for example, a powder mixer.

[0112] The mixing step 130 is generally carried out over a sufficient period of time to create an intimate mixture between the different constituents of the construction binder according to the invention. For example, the mixing step 130 of the constituents of the construction binder of the binder may comprise mixing, before adding water and / or aggregates, of said constituents for at least 5 seconds, preferably at least 10 seconds, more preferably at least 30 seconds and even more preferably at least 1 minute. The step of mixing the constituents, before adding water and / or aggregates, may for example not last more than 30 minutes, preferably more than 20 minutes, more preferably more than 10 minutes and more preferably more than 5 minutes.

[0113] It should be noted that in a particular embodiment the raw clay matrix and the recycled concrete fines are mixed first, then the deflocculating polymer can be added. In a preferred embodiment, the clay matrix already comprises the deflocculating polymer.

[0114] According to another aspect, the invention relates to a method of manufacturing a construction material according to the invention. The manufacturing method according to the invention can be implemented with devices or systems usually used for the manufacture of construction binder or construction materials.

[0115] The method for manufacturing a construction material according to the invention comprises the following steps: a step of forming the construction binder, a step of adding water and a step of adding aggregates.

[0116] According to another aspect, the present invention relates to a construction material capable of being formed, preferably formed, from a construction binder according to the invention. Advantageously, the construction material can be formed from a construction binder obtained according to the method 100 for preparing a binder according to the invention. Furthermore, a construction material according to the invention is capable of being obtained, preferably can be obtained, from a method 100 for preparing a binder according to the invention. AGGREGATES

[0117] A building material according to the present invention may comprise aggregates.

[0118] Conventionally, aggregates can correspond to natural aggregates, artificial aggregates or even recycled aggregates.

[0119] The aggregates may also comprise mineral aggregates, i.e. mainly consisting of mineral matter and / or plant aggregates, i.e. mainly consisting of matter of plant origin. The aggregates may also comprise marine aggregates, i.e. mainly consisting of organic or inorganic matter from the seabed such as siliceous aggregates and / or calcareous substances (e.g. maerl and shell sands).

[0120] Mineral aggregates can, for example, correspond to sand, gravel, gravel, fillers (or fine materials), powders, fossilized waste and their combination.

[0121] Plant aggregates may, for example, correspond to wood (chips or fibers), hemp, straw, hemp shiv, miscanthus, sunflower, typha, corn, flax, rice husks, wheat husks, rapeseed, algae, bamboo, cellulose wadding, defibrated fabric and their combination.

[0122] In particular, when the construction material according to the invention comprises plant aggregates, said material preferably comprises at least 0.1% by weight of plant aggregates, preferably at least 0.2% by weight of plant aggregates, more preferably at least 0.5% by weight of plant aggregates, and even more preferably at least 0.7% by weight of plant aggregates. EXAMPLES

[0123] The invention is described in more detail below with reference to the following experimental examples. These examples are provided for illustrative purposes only and are not intended to be limiting unless otherwise indicated. Thus, the invention should in no way be construed as being limited to the following illustrative examples, but rather should be construed as encompassing all variations that become apparent as a result of the teaching provided herein.

[0124] Preparation of a construction binder and a measuring mortar:

[0125] In all the examples presented below, the formulations according to the invention are prepared according to an identical protocol.

[0126] Recycled concrete fines are generated via a standard process. Briefly, concrete debris is collected from demolition sites. The debris is first processed to remove contaminants such as metal, plastic, and wood with magnets, air separators, and hand or mechanical screens. The contaminant-free concrete is crushed using an impact crusher to reduce its size into more manageable pieces. The aggregates are then passed through vibrating screens to separate the fines from the larger aggregates. Screens with different mesh sizes are used to achieve a particle size such as D50 <750 pm.

[0127] The raw clay matrix is pretreated using a lump crusher or bucket crusher, for example at 100 rpm, then crushed, for example, by a blade crusher at 1200 rpm. Elements larger than 2 mm are removed.

[0128] A dry premix is made between recycled concrete fines, a raw clay matrix, an activator, a precursor and a deflocculating polymer in predetermined quantities, then water is added and the solution is mixed at low speed, i.e. substantially sixty revolutions per minute for thirty seconds. Then, sand is added to the premix and the whole is mixed at higher speed, i.e. approximately 120 revolutions per minute for one minute.

[0129] The water to dry matter mass ratio of the composition (also called construction binder) is adjusted to a value between 0.4 and 0.6. In a particular example, the construction material, a mortar, comprises 25% by weight of binder, 75% by weight of sand; this mixture being supplemented with water for a water to dry matter mass ratio of the binder adjusted to a value of 0.45.

[0130] The mortar based on the construction binder thus formed is then poured into a mold and left to mature at room temperature, i.e. approximately 20 degrees Celsius, for twenty-eight days in water.

[0131] Alternatively, the mortar may be poured into a mold and then left to mature for less than twenty-four hours in a curing step, at room temperature, i.e. approximately 25 degrees Celsius or preferably under heat treatment. During this curing step, the mold may be made airtight or the top layer of the building material may be covered with a curing product to limit / prevent evaporation.

[0132] Table 2 below shows, for different formulations of construction binders including two comparative formulations (REF1, REF2) and five formulations according to the invention (1, 2, 3, 4, 5). The mass of the components relating to each formulation is expressed as a percentage of the total mass of the construction binder (dry weight). In addition, the W / C value is reported. [Tables 2] ID Recycled concrete fines Activator Raw clay Precursor Deflocculating agent W / C CEMI 0 100% (including 5% gypsum) 0 0% 0 0.45 CEMII IB 0% 30% 0 70% 0 0.45 REF1 28.6% 50% 0% 20% 1.4% 0.45 REF2 38.6% 40% 0% 20% 1.4% 0.45 1 33.6% 40% 25% 0% 1.4% 0.5 2 28.6% 40% 10% 20% 1.4% 0.45 3 48.6% 30% 5% 15% 1.4% 0.45 4 43.6% 20% 15% 20% 1.4% 0.45 5 58.6% 15% 15% 10% 1.4% 0.45 Methodology for measuring the mechanical properties of construction binders:

[0133] Once maturation is complete, the mechanical resistance is measured. The mechanical resistance of a construction binder is understood to mean its compressive strength, such compression being measured according to standard NF EN 196-1, for a prism with a side of 40 millimeters and a length of 160 millimeters and is expressed in Mega Pascal (MPa).

[0134] Comparison of the construction binders according to the invention with known construction binders:

[0135] Table 3 below presents the results of the mechanical resistances at 1 day and at 28 days according to the formulations detailed in Table 2. [Tables 3] ID Rclj (MPa) Rclj (Compared to REF1) Rc 28j (MPa) CEMI >15 - >40 CEMIIIB 6 - >40 REF1 8.11 - 45 REF2 7.9 97.41% 36 1 11.4 140.57% 35 2 12 147.97% 41 3 8.6 106.04% 42 4 11.3 139.33% 43 5 12.2 150.43% 40

[0136] Table 3 below shows that the reference formulation REF1, which does not include raw clay in combination with recycled concrete fines, has a fairly low Rc at 1 day (less than 10) but a high Rc at 28 days. Thus, a formulation combining raw clay in combination with recycled concrete fines makes it possible to offer a high-performance construction binder.

[0137] The combined use of recycled concrete fines, a raw clay matrix, a calcined clay matrix, an activator and a precursor makes it possible to maintain a mechanical resistance at 28 days greater than 40 MPa while increasing the Rc at young age (1 day). In addition, certain ratios of raw clays to recycled concrete fines in the presence of a precursor make it possible to achieve good mechanical resistance values at young age and at 28 days.

[0138] The invention may be the subject of numerous variants and applications other than those described above. In particular, unless otherwise indicated, the different structural and functional characteristics of each of the implementations described above should not be considered as combined and / or closely and / or inextricably linked to each other, but rather as mere juxtapositions. Furthermore, the structural and / or functional features of the different embodiments described above may be subject in whole or in part to any different juxtaposition or any different combination.

Claims

Claims

1. Construction binder comprising at least 5% by weight of recycled concrete fines, at most 40% by weight of activator(s), at least 5% of raw clay matrix(es), and at least one deflocculating polymer.

2. Construction binder according to claim 1, characterized in that it further comprises at least 5% by weight of precursor.

3. Construction binder according to claim 2, characterized in that the precursor is selected from: slags such as blast furnace slags, steelworks slags, cupola slags, fly ash, natural pozzolans, silica fumes, micronized limestone fillers, micronized siliceous fillers such as glass powder, siliceous fillers, synthetic vaterite, diatomaceous earth, ground slag or combinations thereof.

4. Construction binder according to claim 3, characterized in that the precursor is selected from: blast furnace slag, micronized limestone filler, vaterite such as micrometric or nanometric vaterite; or combinations thereof.

5. Construction binder according to any one of the preceding claims, characterized in that the recycled concrete fines have a D50 of less than or equal to 1000 pm, preferably less than or equal to 750 pm.

6. Construction binder according to any one of the preceding claims, characterized in that the recycled concrete fines have a pozzolanic activity greater than or equal to 30% as measured according to method A of standard ASTM C1897.

7. Construction binder according to any one of the preceding claims, characterized in that the recycled concrete fines have an oxide composition such that CaO represents at least 20% by weight of the recycled concrete fines.

8. Construction binder according to any one of the preceding claims, characterized in that the recycled concrete fines have a composition such that 3CaOSiO2 represents at least 5% by weight of the recycled concrete fines.

9. Construction binder according to any one of the preceding claims, characterized in that the recycled concrete fines have a composition such that 2CaOSiO2 represents at least 5% by weight of the recycled concrete fines.

10. Construction binder according to any one of the preceding claims, characterized in that it comprises at least 10% by weight of raw clay matrix(s) relative to the dry weight of construction binder.

11. Construction binder according to any one of the preceding claims, characterized in that it comprises at least 15% by weight of activator(s), preferably at least 15% by weight of CEM I as activator, relative to the dry weight of construction binder.

12. Construction binder according to any one of the preceding claims, characterized in that it comprises at most 60% by weight of recycled concrete fines relative to the dry weight of the construction binder.

13. Construction binder according to any one of the preceding claims, characterized in that the raw clay matrix and the recycled concrete fines are present in an amount such that the mass ratio by weight between the raw clay matrix and the recycled concrete fines is between 0.1 and 0.75; limits included.

14. Construction binder according to any one of the preceding claims, characterized in that the D50 of the raw clay matrix is less than 200 pm and the D50 of the recycled concrete fines is greater than 200 pm; preferably the D50 of the raw clay matrix is less than 150 pm and the D50 of the recycled concrete fines is greater than 250 pm; the D50 preferably being measured according to the ISO 13320:2020 standard or according to the NF EN 933-1 standard, preferably according to the NF EN 933-1 standard.

15. Construction binder according to any one of claims 1 to 13, characterized in that the D50 of the raw clay matrix is greater than 200 pm and the D50 of the recycled concrete fines is less than 200 pm; preferably the D50 of the raw clay matrix is greater than 250 pm and the D50 of the recycled concrete fines is less than 150 pm; the D50 preferably being measured according to the ISO 13320:2020 standard or according to the NF EN 933-1 standard, preferably according to the NF EN 933-1 standard.

16. A method of preparing (100) a construction binder according to any one of claims 1 to 15, characterized in that it 26 comprises a step of mixing (130) at least a portion of the constituents of the construction binder then a step of adding water.

17. A building material formed from a building binder according to any one of claims 1 to 15 and further aggregates.

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