Low-carbon construction binders and related construction materials

Abstract

The present invention relates to a construction binder comprising 35% to 65% by weight of clinker, 5% to 30% by weight of a calcined clay matrix, 5% to 30% by weight of a raw clay matrix, and 0.05% to 5% by weight of a deflocculating agent, wherein the ratio of raw clay matrix to calcined clay matrix is ​​0.2 to 7. The present invention further relates to a construction material comprising the construction binder according to the present invention.

Description

[Technical Field]

[0001] The present invention relates to the field of construction, more particularly to the field of low-carbon construction materials. In particular, the present invention relates to a low-carbon construction binder comprising a raw clay matrix and a calcined clay matrix. Furthermore, the present invention relates to a construction material made from the construction binder according to the present invention. [Background technology]

[0002] The known prior art from which the present invention was discovered will now be described.

[0003] Cement is the second most consumed resource in the world, with over 4 billion tons produced worldwide each year. This consumption is constantly increasing, driven by the growing demand for housing and infrastructure. Cement is used, particularly in the manufacture of masonry elements that rely on cementitious materials as binders. Because new infrastructure is constantly being developed in most countries around the world, there is a constant demand for the supply of mineral resources for the formation of construction binders, more specifically, cement, especially Portland cement. However, the production and use of Portland cement is associated with a high environmental footprint. The cement used in the construction industry is generally Portland cement, a hydraulic binder that hardens and hardens when mixed with water. After hardening, the cement retains its strength and stability even when exposed to water. A wide variety of cements are used worldwide. However, all traditional cements contain clinker, the percentage of which varies from 5% in some blast-furnace cements to at least 95% in Portland cement, the most widely used cement in the world today. Clinker is made by burning a mixture of about 80% limestone and 20% aluminosilicates (such as clay). This burning, known as clinkering, is typically carried out at temperatures exceeding 1200°C, making this cement preparation process highly energy-intensive. In addition, the chemical conversion of limestone to lime also releases carbon dioxide. As a result, the cement industry generates about 8% of global CO2 emissions.

[0004] In fact, it is estimated that the production of Portland-type construction binders generates an average of 0.8 kg of CO2 per kg of Portland cement clinker produced. Therefore, various solutions have been developed to try to at least partially replace certain components of the construction binders used to form Portland-type cement. These solutions are primarily aimed at reducing the carbon footprint.

[0005] The first solution, described in document EP 3274315, concerns a construction composition that allows the use of readily available reactive materials, has a low ecological impact, and does not require lengthy and costly heat treatment. To this end, the construction composition comprises a matrix primarily containing a compound based on "flash" metakaolin, i.e., obtained by rapidly firing powdered clay at temperatures between 600°C and 900°C for a few seconds followed by rapid cooling, and an alkaline activation solution. The composition further comprises a mass fraction of cement or clinker of less than 10%, while the alkaline activation solution contains a source of sodium or potassium silicate and an alkaline base. The relative proportions of the activation solution and the matrix are such that the sum of the moles of sodium silicate and alkaline base in the activation solution is 3.5 to 5.5 moles per kg of matrix, and the overall molar ratio of sodium silicate to alkaline base in the alkaline activation solution is 1.25 to 1.65.

[0006] The second solution is that described in document WO2010130511 and involves the use of at least 65% by weight of Portland cement clinker, calcined clay made at temperatures between 500°C and 900°C, and a viscosity of 3000 to 15000 cm 2 We propose a construction material containing ground carbonate with a specific surface area of ​​0.25 to 3.0 / g, with a weight ratio of fired clay material to carbonate material of 0.25 to 3. This construction material maintains higher mechanical strength than Portland-type cement and reduces CO2 emissions during cement production.

[0007] Although these solutions allow the production of construction materials with mechanical strength similar to that of Portland cement, such as Portland cement type CEM1 or CEM2, the composition of the construction binders from which these construction materials are made still requires large amounts of calcined components, such as calcined clay and / or Portland cement clinker. Therefore, the carbon footprint of these construction materials can be further improved. However, the main challenge lies in maintaining the mechanical compressive strength and rheology close to that of Portland cement type CEM2, not only at an early stage (1 day) but also at 28 days, while reducing the carbon footprint of the resulting construction materials.

[0008] The present invention aims to remedy the drawbacks of the prior art, in particular to propose a low-carbon construction binder that has an improved carbon footprint and an improved energy balance compared to prior art construction binders, while ensuring compressive strength and rheology close to those of CEM2 type Portland cement.

[0009] The present invention further aims to propose a low-carbon construction material made from the construction binder according to the invention, said construction material having a compressive strength at least equal to that of Portland cement and having an improved carbon and energy footprint compared to prior art construction materials. Summary of the Invention

[0010] The present invention aims to overcome these drawbacks.

[0011] The present invention relates in particular to a construction binder, - 35% to 65% by weight of clinker, - 5% to 30% by weight of a calcined clay matrix, - 5% to 30% by weight of a raw clay matrix, and - 0.05% to 5% by weight of deflocculating agent Including, The present invention relates to a construction binder, wherein the mass ratio of raw clay matrix to calcined clay matrix is ​​0.2 to 7.

[0012] The combination of raw clay and partially substituted calcined clay can reduce the carbon footprint compared to conventional LC3 type construction binders by limiting the required content of first calcined components, e.g., CEM1 type cement or calcined clay matrix, and reducing the energy input required to form the construction material. Furthermore, the construction binder according to the present invention also ensures the maintenance of a compressive strength of more than 5 MPa at an early age and an improved rheology of the construction binder in the fresh state.

[0013] According to other optional features, the construction binder according to the invention may comprise the following features, alone or in combination: - Not more than 25% by weight of precursors. The precursor comprises a calcium carbonate source. the precursor is selected from blast furnace slag, fly ash, silica fume, natural or synthetic limestone fillers, siliceous fillers, diatomaceous earth; - Calcium carbonate has a D50 of 0.1 microns to 5 microns. - Calcium carbonate contains vaterite. The deflocculating agent is an organic deflocculating agent. The clay matrix has a D50 substantially equal to 10 μm. - 35% by weight of clinker. - Maximum 65% by weight of clinker. - 35% to 50% by weight of clinker. - 20% by weight of precursor. - 15% to 20% by weight of precursor. - 5% by weight of calcined clay matrix. - at least 10% by weight of raw clay matrix. - at least 30% by weight of raw clay matrix. - The fired clay matrix is ​​a flash clay matrix. - The fired clay matrix is ​​natural pozzolanic stone. - The calcined clay matrix is ​​metakaolin. - Construction binders, at least, 40% to 55% by weight of clinker, o not more than 25% by weight of precursors, 5% to 15% by weight of a calcined clay matrix, 15% to 30% by weight of a raw clay matrix, and 0.05% to 2% by weight of deflocculating agent Including, The mass ratio of raw clay matrix to calcined clay matrix is ​​0.5-6. - Construction binders, at least 39% by weight of clinker, 20% by weight of precursor, 10% by weight of a calcined clay matrix, 30% by weight of raw clay matrix, and 1% by weight of deflocculant Includes. - Construction binders 39% by weight of clinker, 20% by weight of precursor, 20% by weight of a calcined clay matrix, 20% by weight of raw clay matrix, and 1% by weight of deflocculant Includes.

[0014] According to a second object, the present invention further relates to a construction material comprising the construction binder according to the invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Other characteristics and advantages of the invention will be better understood on reading the following description and on referring to the accompanying drawings, which are given for the purposes of illustration and are in no way limiting.

[0016] Below, we will first provide an overview of the present invention and related terms, then present the disadvantages of the prior art, and finally describe in more detail how the present invention overcomes them.

[0017] In the remainder of this specification, the term "wt. %" in relation to a construction binder should be understood to mean a percentage relative to the dry weight of the construction binder. The dry weight corresponds, for example, to the weight before adding water required to form the construction material. When wt. % values ​​are given as intervals, the upper and lower limits are included.

[0018] Within the meaning of the present invention, the term "clay matrix" may refer to one or more rock materials based on phyllosilicates, hydrated silicates, or aluminosilicates with a layered structure, which are composed at least in part of fine particles resulting from the transformation of silicates, generally with a three-dimensional framework, or the precipitation of supersaturated fluids. Thus, the clay matrix may contain a mixture of such rock materials, such as kaolinite, serpentine, pyrophyllite, talc, smectite, vermiculite, illite, glauconite, mica, chlorite, palygorskite, sepiolite, mixed-layer materials, or mixtures thereof (Alain Meunier, Clays, 2005). Furthermore, the clay matrix may contain loam or silt. The clay matrix may be derived from, but is not limited to, construction site waste, quarry fines, clay limestone fines, washed fines, clay sludge, stripped material, clayey excavated material such as excavated soil, or sediments (including dredged sediments and varves), phyllosilicate rocks and alterites such as turbidite, marl, perite, ruffle, laterite, schist, mica schist, and the like.

[0019] "Concrete" means a mixture of aggregate, possibly sand, with a construction binder (e.g., cement) and water. The term concrete can therefore correspond to a construction element formed from a mixture of mineral or vegetable aggregate, possibly including sand, one or more additives, a construction binder and water.

[0020] The expression "raw clay matrix" within the meaning of the present invention corresponds to a clay matrix that has not undergone a calcination step. Specifically, it does not undergo any prior heat treatment. For example, it corresponds to a clay matrix that has not undergone a temperature increase above 300°C, preferably above 200°C, and more preferably above 150°C. In fact, the raw clay matrix can be subjected to a drying step, which generally requires a temperature increase substantially equal to or lower than 150°C, but not a calcination step. The raw clay matrix preferably comprises a rock material, which can include, for example, kaolinite, serpentine, pyrophyllite, talc, smectite, vermiculite, illite, glauconite, mica, chlorite, palygorskite, sepiolite, mixed-layer rocks, or mixtures thereof.

[0021] For purposes of this invention, a "deflocculating agent," "deflocculant," or "deflocculation agent" can correspond to a compound capable of dissociating aggregates and colloids, particularly in aqueous suspension. For example, deflocculants are used in drilling or oil extraction situations to make clay more fluid and easier to mine or excavate.

[0022] The term "binder" or "construction binder" can be understood within the meaning of the present invention as a compound that makes it possible to ensure the cohesion of materials, in particular during the setting and hardening of the construction material. It therefore ensures, in particular, the cohesion of sand and other aggregates with the binder's constituents. The binder according to the invention is in particular a hydraulic binder, i.e. the hardening occurs upon contact with water.

[0023] The term "Portland cement" refers to a hydraulic binder composed primarily of hydraulic calcium silicate, which is capable of setting and hardening by chemical reaction with water. Portland cement generally contains at least 95% clinker and up to 5% secondary components, such as alkalis (Na2O, KO), magnesia (MgO), gypsum (CaSO4·2H2O), or various trace metals.

[0024] Within the meaning of the present invention, the expression "metal oxide" may refer to a composition containing a metal oxide, such as an aluminate. In particular, the construction binder according to the present invention may contain a metal oxide composition containing more than 25% by weight of metal oxide, preferably more than 30% by weight of metal oxide, more preferably more than 40% by weight of metal oxide, and even more preferably more than 45% by weight of metal oxide. For example, the metal oxide composition may contain more than 2% by weight of aluminate, preferably more than 5% by weight of aluminate, more preferably more than 7% by weight of aluminate, and even more preferably more than 10% by weight of aluminate. Furthermore, the metal oxide may correspond to or contain an alkaline earth oxide. For example, the metal oxide composition may contain more than 10% by weight of calcium oxide, preferably more than 20% by weight of calcium oxide, more preferably more than 25% by weight of calcium oxide, and even more preferably more than 30% by weight of calcium oxide by dry weight. The metal oxide composition may also contain species that are not metal oxides. For example, the metal oxide composition may be replaced by aluminum or silicon oxide, for example, containing more than 10% by weight of aluminum or silicon oxide, preferably more than 20% by weight of aluminum or silicon oxide, more preferably more than 25% by weight of aluminum or silicon oxide, and even more preferably more than 30% by weight of aluminum or silicon oxide. These mass concentrations can be easily determined by those skilled in the art using conventional techniques for measuring metal oxides or aluminum or silicon oxides. In particular, the expression "metal oxide composition" refers to a composition containing more than 50%, preferably more than 70%, more preferably more than 80%, and even more preferably more than 90% of metal oxide and / or aluminum or silicon oxide (including aluminates). Preferably, the metal oxide composition corresponds to slag from metallurgy, such as blast furnace slag or fly ash. The "metal oxide" composition is preferably a calcined metal oxide composition, i.e., it has been subjected to a high-temperature process. This high-temperature process may be natural or artificial, in which case it is a high-temperature treatment.The high-temperature process may correspond, for example, to a treatment at a temperature of 400° C. or higher, preferably 750° C. or higher, more preferably 900° C. or higher, and even more preferably above 1000° C. The metal oxide composition of the composition or construction element can be determined by X-ray fluorescence ("Standard Test Methods for Chemical Analysis of Hydraulic Cement", December 2022; ASTM C114-18 or according to standard EN ISO 29581-2:2010).

[0025] The term "substantially equal" corresponds, within the meaning of the present invention, to values ​​that vary by less than 20%, preferably less than 10%, and more preferably less than 5% compared to a comparison value.

[0026] The term "clinker" or "Portland clinker" refers to a component of cement, which is obtained by firing a mixture consisting of approximately 80% limestone and 20% aluminosilicates (such as clays). This firing, or clinkering, is generally carried out at temperatures above 1200°C, which is particularly energy-intensive and produces high greenhouse gas emissions. The clinker is generally crushed, and then 5% gypsum, anhydrite, and / or bassanite are added to produce CEM1 type Portland cement.

[0027] The term "D50" refers to the median diameter at which 50% (by volume or mass, preferably by volume) of the grains, particles, aggregates, or sediments are smaller than a given diameter. For example, if sieve and sedimentation analysis indicates D50=5.8 mm, then 50% (by volume or mass, preferably by volume) of the sample particles are larger than 5.8 mm and 50% are smaller than 5.8 mm. D50 is generally used to describe the particle size of a group of particles. D50 can be measured by any method known to those skilled in the art. D50 is preferably measured according to the ASTM D422-63 standard, XP P 94-041 (1995), NF ISO 11277 (2020), NF EN ISO 17892-4 (2018) standard, or ASTM D6913-04 (2009) standard, or, in particular for fine particles, according to the ISO 13320:2020 standard (e.g., D10 or <65 μm).

[0028] The construction industry needs to evolve to optimize productivity while responding to social and environmental challenges. In this context, research institutes and manufacturers have proposed low-carbon construction binders containing reduced amounts of Portland clinker, or have attempted to replace Portland clinker with other calcined components that have a lower carbon footprint than Portland clinker. However, these mixtures still contain high amounts of Portland clinker and / or calcined components.

[0029] In fact, even if the construction binder does not contain Portland clinker, the latter still accounts for approximately 50% by weight of the construction binder in the burnt composition, and has the disadvantage of not having the same mechanical resistance as Portland cement of type CEM1 or CEM2.

[0030] However, there is an urgent need to reduce the carbon footprint of the construction industry and further limit the use of Portland cement or Portland clinker or replace Portland cement / clinker with other components that have a lower or no carbon footprint. To address this, the inventors have developed a construction binder comprising specific proportions of clinker, raw clay matrix and calcined clay matrix that allows for a reduction in the amount of clinker and calcined clay matrix compared to construction binders containing clinker and / or calcined components, while still providing a mechanical strength at 1 day of at least 5 MPa, preferably 10 MPa, and a mechanical strength at 28 days of at least 30 MPa, preferably 40 MPa.

[0031] Therefore, the present invention particularly relates to a low-carbon construction binder comprising clinker, a calcined clay matrix, a raw clay matrix and a deflocculating agent, wherein the mass ratio of the raw clay matrix to the calcined clay matrix is ​​0.2-7.

[0032] The construction binder according to the invention can be prepared without prior preparation or can be prepared at a manufacturing site and then optionally stored and transported to the construction site.

[0033] The general and preferred characteristics of each of the components of the formulation according to the invention are detailed below.

[0034] Raw clay matrix

[0035] The raw clay matrix can include at least one mineral species selected from, for example, illite, kaolinite, smectite, vermiculite, chlorite, montmorillonite, muscovite, halloysite, sepiolite, and palygorskite.

[0036] Preferably, the raw clay matrix comprises at least two clays selected from illite, kaolinite, smectite, vermiculite, chlorite, montmorillonite, muscovite, halloysite, sepiolite, mixed layer, pyrophyllite, talc, serpentine, and palygorskite, including clays known as mixed-layer clays, which are complex combinations of several clays. More preferably, the raw clay matrix comprises at least one mineral species selected from kaolinite, illite, smectite, palygorskite, sepiolite, chlorite, montmorillonite, and vermiculite.

[0037] Table 1 below shows the chemical properties of these mineral species.

[0038] [Table 1]

[0039] Additionally, the raw clay matrix may also contain montmorillonite and / or clays called mixed layer clays, which are complex combinations (on an atomic scale) of several clays.

[0040] The type of clay can be determined by methods known to those skilled in the art. Specifically, X-ray diffraction can be used after specially preparing the sample according to a method known as the oriented blade method (see Thiry et al., 2013 - Introduction to the preparation techniques and interpretation of clay minerals for analysis by X-ray diffraction). For example, the following conditions can be used: - Equipment: diffractometer, e.g., BRUKER D8 ADVANCE (Bragg-Brentano geometry); e.g., the following settings: copper tube (λ Kα1 ≈ 1.54 Å); generator power: 40 kV, 40 mA; primary optics: 0.16° fixed slit; secondary optics: 2.5° Soller slit; LynXeye XE-T detector - Acquisition parameters: scan 4–70°2θ; scan speed 0.03°2θ / s; counting time: 20–60 min per pitch; sample rotation.

[0041] The raw clay matrix may preferably correspond, at least in part, to excavated clayey soil, preferably uncalcined excavated clayey soil, such as processed raw excavated clayey soil. The raw clay matrix may advantageously be processed, said processing being selected from crushing, sorting, sieving and / or drying. Preferably, the raw clay matrix used in the binder is crushed.

[0042] Preferably, the construction binder according to the invention comprises at least 5% by weight of raw clay matrix, more preferably at least 15% by weight of raw clay matrix. Indeed, the construction binder according to the invention has the advantage that it can contain a large amount of raw clay matrix without altering the mechanical properties of the construction material.

[0043] Furthermore, preferably, the construction binder according to the invention comprises at most 30% by weight of raw clay matrix, more preferably at most 25% by weight of raw clay matrix.

[0044] Thus, in particular, the construction binder according to the invention comprises 5% to 30% by weight of raw clay matrix, preferably 10% to 28% by weight or 15% to 27% by weight of raw clay matrix, more preferably 20% to 26% by weight of raw clay matrix, even more preferably 22% to 25% by weight of raw clay matrix.

[0045] Advantageously, the raw clay matrix may comprise crushed raw clay. Preferably, the D50 of the raw clay matrix is ​​500 μm or less, preferably 250 μm or less, more preferably 100 μm or less, or even more preferably 50 μm or less.

[0046] Furthermore, the D50 of the raw clay matrix may be 0.1 μm or more, preferably 1 μm or more, more preferably 10 μm or more, or even more preferably 20 μm or more, more preferably 40 μm or more, which makes it possible to limit the constraints of industrial production tools dedicated to grinding.

[0047] More preferably, the D50 of the raw clay matrix may be 10 μm to 500 μm, preferably 15 μm to 250 μm, more preferably 20 μm to 150 μm, and even more preferably 20 μm to 50 μm. The presence of clay that has been crushed to achieve such diameters can improve the performance of the construction binder and construction material according to the present invention.

[0048] Advantageously, the raw clay matrix can contain at least 2% by weight, preferably at least 4% by weight, and more preferably at least 6% by weight of loam particles. For example, the raw clay matrix can contain up to 50% by weight, preferably up to 30% by weight, and more preferably up to 20% by weight of loam particles. For example, the raw clay matrix can contain 2% to 50% by weight, preferably 4% to 30% by weight, and more preferably 6% to 20% by weight of loam particles. The loam particles are particularly particles with a diameter of 2 μm to 63 μm.

[0049] The raw clay matrix can contain at least 1% by weight, preferably at least 2% by weight, and more preferably at least 3% by weight of sand. For example, the raw clay matrix can contain up to 70% by weight, preferably up to 50% by weight, and more preferably up to 40% by weight of sand. For example, the raw clay matrix can contain 1% to 70% by weight, preferably 2% to 50% by weight, and more preferably 3% to 40% by weight of sand particles. The sand corresponds particularly to particles with a diameter of 63 μm to 2 mm.

[0050] Preferably, the raw clay matrix has a clay content, in the mineralogical sense, of at least 10% by dry weight, more preferably at least 20% by dry weight, and even more preferably at least 30% by dry weight. However, raw clay matrices with lower clay contents in the mineralogical sense may also be used. In particular, the raw clay matrix may correspond to fine clay-limestone or clay-silica / quartz particles containing at least 50% by dry weight of limestone, silica, or quartz, preferably at least 60%, more preferably at least 70%, or even more preferably at least 80% by dry weight of limestone, silica, or quartz.

[0051] Calcined Clay Matrix

[0052] The calcined clay matrix may be a raw clay material that has been previously subjected to a heat treatment, preferably at a temperature of at least 450°C and up to 900°C, or in a flash calcination process at a temperature of 800°C to 1100°C.

[0053] Preferably, the calcined clay material is dehydroxylated to an amorphous material while preventing the formation of high temperature aluminosilicate crystalline phases such as mullite.

[0054] The calcined clay matrix is ​​preferably amorphous and has porosonic activity.

[0055] Furthermore, the calcined clay matrix can contain at least 5% by weight of metal oxide, preferably at least 10% by weight of metal oxide, preferably at least 20% by weight of metal oxide, and more preferably at least 30% by weight of metal oxide. The calcined clay matrix can further contain up to 70% by weight of metal oxide, preferably up to 60% by weight of metal oxide.

[0056] The calcined clay matrix can be formed by any of the clay matrices already mentioned above. The calcined clay matrix can contain at least one mineral species selected from, by way of non-limiting example, metakaolin, metalite, and / or metamontmorillonite. Preferably, the calcined clay matrix contains kaolinite and / or illite. Therefore, preferably, the calcined clay matrix corresponds to metakaolin or metalite.

[0057] According to a preferred embodiment of the invention, the calcined clay matrix is ​​composed of metakaolin, a material resulting from the calcination of kaolinite or kaolinite-rich minerals, e.g., those having a kaolinite content of at least 20% by weight, preferably at least 25% by weight, and more preferably at least 30% by weight.

[0058] Preferably, the calcined clay matrix is ​​a flash clay matrix, such as metakaolin from flash calcination.

[0059] Alternatively, the calcined clay matrix may be derived from natural pozzolanic rock, i.e., formed by volcanic basalt outcrops or from rocks of similar composition, or more generally, from any material that has "pozzolanitic properties," i.e., the ability to combine with lime or portlandite in the presence of water at room temperature to give a very insoluble hydrate.

[0060] Preferably, the construction binder according to the invention comprises at least 5% by weight of calcined clay matrix, more preferably at least 15% by weight of calcined clay matrix. Indeed, the construction binder according to the invention has the advantage that it can contain small amounts of raw clay matrix without altering the mechanical properties of the construction material.

[0061] Furthermore, preferably, the construction binder according to the invention comprises at most 30% by weight of a calcined clay matrix, more preferably at most 25% by weight of a calcined clay matrix.

[0062] Therefore, in particular, the construction binder according to the present invention comprises 5% to 30% by weight of calcined clay matrix, preferably 10% to 25% by weight or 10% to 20% by weight of calcined clay matrix, more preferably 12.5% ​​to 20% by weight of calcined clay matrix, and even more preferably 12.5% ​​to 15% by weight of calcined clay matrix.

[0063] Preferred mass ratio

[0064] As shown in the examples, the Applicant has found that a specific mass ratio between the raw clay matrix and the calcined clay matrix of the construction binder makes it possible to obtain advantageous mechanical resistance properties at an early age and at 28 days.

[0065] Advantageously, in the construction binder according to the invention, the calcined clay matrix and the raw clay matrix are present in an amount such that the mass ratio by weight of raw clay matrix to calcined clay matrix is ​​between 0.33 and 3 (upper and lower limits included). Indeed, as shown in the examples, such a mass ratio makes it possible to obtain a high Rc at 1 day (for example, greater than 7 MPa) while maintaining an Rc of at least 30 MPa at 28 days.

[0066] Deflocculating agent

[0067] Many compounds can function as peptizers, many of which are commonly known to those skilled in the art.

[0068] The presence of one or more deflocculants can improve the performance of materials formed from the construction binder.

[0069] In the context of the present invention, the construction binder may comprise an organic deflocculating agent, advantageously a deflocculating polymer. According to the present invention, the organic deflocculating agent comprises at least one carbon atom, preferably at least one carbon-oxygen bond.

[0070] The deflocculating polymer may be a non-ionic surfactant, such as a polyoxyethylene ether, which may be selected from, for example, lauryl poly(oxyethylene) ether.

[0071] The deflocculating polymer may also be an anionic agent, such as an anionic surfactant, etc. Specifically, the anionic agent may be selected from alkylarylsulfonates, 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.

[0072] The deflocculating polymer may also be a polyacrylate, in which case it may be selected, for example, from sodium polyacrylate and ammonium polyacrylate.

[0073] The deflocculating polymer may also be an amine selected from, for example, 2-amino-2-methyl-1-propanol, mono-, di-, or triethanolamine, isopropanolamines (1-amino-2-propanol, diisopropanolamine, triisopropanolamine), and N-alkylethanolamines.

[0074] Preferably, the deflocculating polymer is selected from lignosulfonates (eg, sodium lignosulfonate), polyacrylates, humates, and mixtures thereof.

[0075] Preferably, the deflocculating polymer is selected from lignosulfonates (eg, sodium lignosulfonate), polyacrylates, humates, polycarboxylates, such as polycarboxylic acid ethers, and the like, and mixtures thereof.

[0076] More preferably, the deflocculating polymer comprises a humate, a lignosulfonate and / or a polyacrylate.

[0077] The peptizer may also be a silicate, such as sodium silicate, sodium metasilicate, or sodium trisilicate.

[0078] Alternatively, the deflocculating agent may be a mixture of compounds, such as a mixture containing at least two compounds selected from nonionic surfactants, anionic agents, polyacrylates, amines, and organophosphorus compounds.

[0079] In particular, the peptizer may be a mixture of sodium silicate and sodium carbonate.

[0080] The peptizer is preferably in the form of a salt.

[0081] However, the present invention is not limited to the above-mentioned deflocculating agents, and any type of deflocculating agent known to those skilled in the art can be used in place of the above-mentioned deflocculating agents.

[0082] The peptizers that can be used in accordance with the present invention can be in solid or liquid form.

[0083] In particular, the deflocculating agent 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, for example at least 1% by weight of the construction binder.

[0084] Furthermore, the deflocculating agent 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. In fact, too high a concentration is not necessary to form a material with advantageous mechanical properties.

[0085] In particular, the deflocculating agent represents 0.05% to 5% by weight of the construction binder, preferably 0.1% to 4% by weight of the construction binder, more preferably 0.25% to 3% by weight of the construction binder, even more preferably 0.5% to 2% by weight of the construction binder, even more preferably 0.8% to 2% by weight of the construction binder, and even more preferably 0.9% to 2% by weight of the construction binder.

[0086] Precursor

[0087] The construction binder according to the present invention may comprise precursors, the role of which, without being limited by theory, is to contribute to the mechanical strength of the construction material.

[0088] The precursor may include a source of carbonate, in combination with or without a silicate. In particular, the precursor may include sodium or potassium carbonate, which may also be mixed with sodium or potassium silicate.

[0089] Preferably, the precursor may comprise a calcium carbonate source, which may correspond to a solid material mainly composed of carbonate minerals, such as calcite or dolomite minerals.

[0090] As an example to help understanding, the source of carbonate may be limestone, dolomite, chalk, aragonite, or vaterite.

[0091] Alternatively, the limestone may also be magnesium carbonate and / or a mixture of magnesium carbonate and dolomite.

[0092] Preferably, the limestone is a natural limestone composed mainly of calcium carbonate in different polymorphic forms, such as calcite and / or aragonite, with some magnesium carbonate and / or dolomite, or may be an argillaceous limestone or natural marl.

[0093] Additionally, the precursors may include siliceous fillers or "quartz flour." For example, siliceous fillers may include corpuscular silica and kaolinite.

[0094] Precursors may also include calcined schist, diatomaceous earth, phonolite, paper mill sludge ash, or crushed glass.

[0095] Additionally, the precursor may include at least 30% by weight calcium oxide or at least 30% by weight calcium carbonate.

[0096] Alternatively or additionally, the precursor may further include blast furnace slag, fly ash, incineration ash, volcanic ash, silica fume, limestone filler, such as finely divided limestone filler of known types, or combinations thereof.

[0097] The precursor may further have a particular particle size, for example, a D50 that characterizes the particle size, where 50% of the precursor's volume (or mass) has a particle size less than 25 microns and 50% of the precursor's volume (or mass) has a particle size greater than 5 microns. Alternatively, the precursor may have a particular particle size, for example, an average particle size that characterizes the average diameter of the particles between 5 microns and 50% of the precursor's volume (or mass) has a particle size greater than 5 microns.

[0098] Alternatively, the precursor, such as calcium carbonate, can have a particular particle size, for example, an average particle size characterizing an average particle size of 0.1 microns to 100 microns, preferably 0.1 microns to 5 microns.

[0099] If the precursor is calcium carbonate, it may be made of vaterite.

[0100] Thus, the calcium carbonate may comprise at least 10% by weight vaterite, or at least 20% by weight vaterite, or at least 30% by weight vaterite, or at least 40% by weight vaterite, or at least 50% by weight vaterite, or at least 60% by weight vaterite, or at least 70% by weight vaterite, or at least 80% by weight vaterite, or at least 90% by weight vaterite, or at least 95% by weight vaterite, or at least 99% by weight vaterite.

[0101] Vaterite forms aragonite in the presence of water. Vaterite can be obtained by any method known to those skilled in the art.

[0102] In the present invention, if the precursor is present, it may be present in a content of at least 1% by weight of the construction binder, preferably in a content of at least 10% by weight of the construction binder, and more preferably in a content of at least 15% by weight of the construction binder.

[0103] 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.

[0104] Thus, in particular, the construction binder according to the invention may comprise 1% to 25% by weight of precursor, preferably 10% to 25% by weight of precursor, more preferably 15% to 20% by weight of precursor.

[0105] clinker

[0106] The construction binder according to the present invention further comprises clinker.

[0107] Clinker is obtained by burning a mixture of approximately 80% limestone and 20% aluminosilicate. This burning, known as clinkering, is generally carried out at temperatures above 1200°C. As mentioned above, clinker can also contain up to 5% gypsum. The role of gypsum is to provide sulfates that slow the setting of cement. Gypsum is commonly added to Portland clinker to form CEM1, but any other component that will provide sulfates and slow the setting of cement can be used in addition to or instead of gypsum, such as basanitite or anhydrite.

[0108] As a non-limiting example, the clinker may be "Portland" clinker, which is composed of at least two-thirds by mass of calcium silicates (3CaO·SiO2:C3S and 2CaO.SiO2:C2S), the remainder being composed of aluminum and iron-containing phases, with no more than 2% free lime (CaO). The mass ratio (CaO) / (SiO2) is generally 2 or greater.

[0109] Preferably, the construction binder according to the invention comprises at least 35% by weight of clinker, more preferably at least 40% by weight of clinker.

[0110] Furthermore, preferably, the construction binder according to the invention comprises at most 60% by weight of clinker, more preferably at most 65% by weight of clinker.

[0111] In particular, the construction binder according to the present invention therefore comprises 35% to 65% by weight of clinker, preferably 40% to 60% by weight or 45% to 60% by weight of clinker, more preferably 45% to 55% by weight of clinker, and even more preferably 45% to 50% by weight of clinker.

[0112] In a particular embodiment, the construction binder according to the present invention comprises: - 40% to 55% by weight of clinker, - 15% to 25% by weight of precursor, - 5% to 15% by weight of a calcined clay matrix, - 15% to 30% by weight of a raw clay matrix, and - 0.05% to 2% by weight of deflocculating agent and the mass ratio of the raw clay matrix to the raw clay matrix is ​​0.2-7.

[0113] In another particular embodiment, the construction binder according to the invention comprises: 39% by weight of clinker, 20% by weight of precursor, preferably the precursor is limestone filler; 10% by weight of a calcined clay matrix, 30% by weight of a raw clay matrix, and - 1% by weight of deflocculant Includes:

[0114] In another particular embodiment, the construction binder according to the invention comprises: 39% by weight of clinker, 20% by weight of precursor, preferably the precursor is limestone filler; 20% by weight of a calcined clay matrix, 20% by weight of a raw clay matrix, and - 1% by weight of deflocculant Includes:

[0115] In another particular embodiment, the construction binder according to the invention comprises: 39% by weight of clinker, 20% by weight of precursor, preferably the precursor is limestone filler; 25% by weight of a calcined clay matrix, 5% by weight of a raw clay matrix, and - 1% by weight of deflocculant Includes:

[0116] In another particular embodiment, the construction binder according to the invention comprises: 50% by weight of clinker, 30% by weight of a calcined clay matrix, 20% by weight of a raw clay matrix, and - 1% by weight of deflocculant Includes:

[0117] Therefore, in another aspect, the present invention relates to a construction material formed from the low-carbon construction binder according to the invention.

[0118] The low-carbon construction binder according to the invention makes it possible to produce insulating construction materials, in particular by adding lightweight aggregates of the "vegetable or porous" type from the construction binder according to the invention, and to produce lightweight concrete from the construction binder according to the invention by adding a foaming agent, such as aluminum powder, which allows to trap air in the material and improve its insulating properties. Prefabricated elements: the production of concrete blocks or slabs in factories from the construction binder according to the invention; and insulating modules. [Example]

[0119] Preparation of construction binder:

[0120] In all the examples below, the construction binders according to the invention are prepared according to the same protocol: a dry premix is ​​made between the predetermined amounts of clinker, raw clay matrix, calcined clay matrix, precursor (except for one example that does not contain a precursor), and deflocculating agent, then water is added and the solution is mixed at low speed, i.e., substantially at 100 revolutions per minute, for 90 seconds, followed by adding water and aggregate to the construction binder and mixing at low speed, i.e., substantially at 100 revolutions per minute, for 45 seconds to obtain the construction material.

[0121] Alternatively, dry premixing can be accomplished by first mixing the raw clay matrix, the calcined clay matrix and the deflocculating agent, and then adding the clinker and precursor (if present) in a second step.

[0122] The mass ratio of water to the dry substance of the composition (also called construction binder) is adjusted to a value of 0.4-0.6. For example, a construction material, mortar, contains 25% by weight of binder and 75% by weight of sand, and this mixture is supplemented with water to adjust the mass ratio of water to the dry substance of the binder to a value of 0.4.

[0123] The mortar based on the construction binder thus formed is then poured into two separate molds, the first of which is left to mature for 24 hours at room temperature, i.e., about 20°C, and the second of which is subjected to underwater curing at 20°C for 28 days.

[0124] Alternatively, the mortar may be poured into a mold and then left to age for a time period of less than 24 hours at room temperature, i.e., about 25° C., or preferably under heat treatment, in a hardening stage. During this hardening process, the mold may be sealed or the top layer of the construction material may be covered with a hardening compound to limit / prevent evaporation.

[0125] Methods for measuring the consistency of construction binders:

[0126] Once the components have been mixed, the consistency of the freshly mixed mortar (hereinafter referred to as rheology) is determined by measuring the cone spreading value as described in standard NF EN 1015-3.

[0127] Methods for measuring the mechanical properties of construction binders:

[0128] Once maturation is complete, the mechanical resistance is measured. The mechanical resistance of a construction binder is its compressive strength, which is measured on a prism with a side of 40 millimeters and a length of 160 millimeters according to standard NF EN 196-1 and is expressed in megapascals (MPa).

[0129] Comparison of the construction binder according to the invention with known construction binders:

[0130] Table 2 below shows different types of known construction binders. The mass of the components for each formulation is expressed as a percentage of the total mass (dry weight) of the construction binder.

[0131] [Table 2]

[0132] Table 2 therefore shows the mechanical resistance of known construction binders (binders CEM2, LC3, REF1 and REF2) which do not form part of the present invention, for example, construction binders of the CEM2 type, better known as Portland limestone cements, which have a compressive strength of the order of 50 MPa.

[0133] The LC3 formulation can be obtained according to the teachings of patent EP 2429966. The LC3 type construction binder contains 30% by weight of metakaolin obtained by calcination of kaolin, 50% by weight of CEM1 and 20% limestone filler. The mechanical resistance of such a construction binder is therefore of the order of 45 MPa, which is close to the resistance of a CEM2 type construction binder.

[0134] Finally, the construction binders REF1 and REF2 are obtained according to the teachings of patent application EP 2 429 966, but by replacing all or part of the calcined clay matrix with a raw clay matrix. These tests show a significant reduction in mechanical strength (12 MPa) when the construction binder does not contain a calcined clay matrix (REF1), and a high mechanical strength (25 MPa) (REF2), much lower than that of references CEM2 and CL3, when the construction binder contains equal proportions of raw and calcined clay matrix. Therefore, the absence of a calcined clay matrix or its presence in equal proportions with the raw clay matrix does not allow concrete with adequate mechanical properties to be obtained.

[0135] Table 3 below shows different types of construction binders according to the invention (MTU01 to MTU05). The mass of the components for each formulation is expressed as a percentage of the total mass (dry weight) of the construction binder. The construction binders shown below differ in particular in the more or less important proportions of raw clay matrix and calcined clay matrix, and one of the example construction binders also contains blast furnace slag as a precursor.

[0136] [Table 3]

[0137] As shown in Table 3, the construction binders according to the present invention have compressive strengths comparable to or greater than those obtained by concrete formed with CEM2 or LC3 cements. The present invention therefore makes it possible to form low-carbon construction binders by further limiting the proportion of clinker and calcined clay matrix used. This therefore makes it possible to further reduce the carbon footprint and energy balance of these construction binders compared to low-carbon binders of CEM2 and LC3 types, resulting in construction materials that meet the majority of industry needs. Finally, the construction binders according to the present invention have the advantage of improved rheology compared to reference construction binders containing calcined and / or raw clay matrices, and of early compressive strengths that allow them to be used to form any type of construction material, for example, thin (less than 200 mm thick) or thick tiles of any nature in reinforced or prestressed concrete, and more generally for masonry work.

Claims

1. A construction binder comprising: 35% to 65% by weight of clinker; 5% to 30% by weight of a calcined clay matrix; 5% to 30% by weight of a raw clay matrix, and 0.05% to 5% by weight of a deflocculating agent Including, A construction binder, wherein the mass ratio of said raw clay matrix to said calcined clay matrix is ​​0.2 to 7.

2. 10. The construction binder of claim 1, wherein the binder further comprises up to 25% by weight of a precursor.

3. 3. The construction binder of claim 2, wherein the precursor comprises a source of calcium carbonate.

4. 4. Construction binder according to claim 2 or 3, wherein said precursor is selected from blast furnace slag, fly ash, silica fume, natural or synthetic limestone fillers, siliceous fillers, diatomaceous earth.

5. 5. The construction binder according to claim 3, wherein the calcium carbonate has a D50 of 0.1 μm to 5 μm.

6. 6. The construction binder according to any one of claims 3 to 5, wherein the calcium carbonate comprises vaterite.

7. 7. The construction binder according to claim 1, wherein the deflocculating agent is an organic deflocculating agent.

8. Construction binder according to any one of the preceding claims, wherein the raw clay matrix has a D50 substantially equal to 10 μm.

9. A construction binder according to any one of the preceding claims, wherein the binder comprises 35% to 50% by weight of clinker.

10. Construction binder according to any one of claims 1 to 9, wherein the binder comprises at least 10% by weight of a raw clay matrix.

11. A construction binder according to any one of claims 1 to 9, wherein the binder comprises at least 30% by weight of a raw clay matrix.

12. A construction binder according to any one of claims 1 to 11, wherein the calcined clay matrix is ​​metakaolin.

13. The binder comprises at least 40% to 55% by weight of clinker; 25% by weight or less of precursors, 5% to 15% by weight of a calcined clay matrix; 15% to 30% by weight of a raw clay matrix, and 0.05% to 2% by weight of a deflocculating agent Including, 10. Construction binder according to any one of claims 1 to 9, wherein the mass ratio of the raw clay matrix to the calcined clay matrix is ​​between 0.5 and 6.

14. The binder is 39% by weight of clinker, 20% by weight of precursor, 10% by weight of calcined clay matrix, 30% by weight of raw clay matrix, and 1% by weight of deflocculant 10. The construction binder according to any one of claims 1 to 9, comprising:

15. The binder is 39% by weight of clinker, 20% by weight of precursor, 20% by weight of calcined clay matrix, 20% by weight of raw clay matrix, and 1% by weight of deflocculant 10. The construction binder according to any one of claims 1 to 9, comprising:

16. A construction material comprising the construction binder according to any one of claims 1 to 15.

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