Low carbon building binders and related building materials

Abstract

The invention relates to a building 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 green clay matrix, and-0.05% to 5% by weight of a deflocculant; and the mass ratio of the green clay matrix to the calcined clay matrix is 0.2 to 7. The invention also relates to a building material comprising a building binder according to the invention.

Description

Technical Field

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

[0002] The known prior art for developing the present invention is described below.

[0003] Cement is the second most consumed commodity in the world, with over 4 billion tons produced annually. This consumption is increasing, driven by the growing demand for housing and infrastructure. Cement is particularly used in the manufacture of masonry units, which rely on cementitious materials as a binder. The continuous development of new infrastructure in most countries around the world has created a constant demand for the supply of construction binders, more specifically, the mineral resources used to form cement, particularly Portland cement. However, the production and use of Portland cement is associated with a high environmental footprint. Portland cement is the most commonly used cement in construction. It is a hydraulic binder that hardens and sets when mixed with water. After hardening, cement maintains its strength and stability even when exposed to water. A variety of cements are used worldwide. However, all conventional cements contain clinker, with the percentage ranging from 5% for some blast furnace cements to a minimum of 95% for Portland cement, the most widely used cement in the world today. Clinker is produced by burning a mixture of approximately 80% limestone and 20% aluminosilicates (e.g., clay). This firing (called clinkerization) typically takes place at temperatures exceeding 1200°C, making the cement-making process energy-intensive. Furthermore, the chemical conversion of limestone into lime releases carbon dioxide. Consequently, the cement industry contributes approximately 8% of global CO2 emissions.

[0004] In fact, it is estimated that the manufacture of Portland-type construction binders produces an average of 0.8 kg of CO₂ / kg of Portland cement clinker produced. Consequently, various solutions have been developed to attempt 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 no. EP 3274315, involves a composition for building materials that allows the use of readily available and reactive materials, has a low ecological impact, and does not require lengthy and expensive thermal treatment. To this end, the composition comprises a base and an alkaline activation solution. The base primarily comprises a compound based on "flashed" metakaolin, that is, a powdered clay obtained by rapid calcination at temperatures between 600°C and 900°C for a few seconds, followed by rapid cooling. The composition also contains less than 10% by weight of cement or clinker, while the alkaline activation solution comprises a source of sodium or potassium silicate and an alkaline base. The relative proportions of the activation solution and the base are such that the total molar content of sodium silicate and alkali metal base in the activation solution is 3.5-5.5 mol / kg of base, and the total molar ratio of sodium silicate to alkali metal base in the alkaline activation solution is 1.25-1.65.

[0006] A second solution described in document no. WO 2010130511 proposes a building material comprising at least 65% by weight of Portland cement clinker, calcined clay produced at a temperature of 500° C. to 900° C. and ground to a density of 3000-15000 cm 2 / g of carbonate with a specific surface area of ​​10000 t / g, wherein the weight ratio of calcined clay material to carbonate material is 0.25 to 3. Compared with Portland cement, this building material allows maintaining high mechanical strength and reducing CO2 emissions during cement production.

[0007] While these solutions allow for the production of building materials with mechanical strengths similar to those of Portland cement, such as Portland cement types CEM1 or CEM2, the composition of the building binder still requires significant amounts of calcined components, such as calcined clay and / or Portland cement clinker, from which these building materials are derived. Therefore, the carbon footprint of these building materials could still be improved. However, the primary challenge lies in maintaining mechanical compressive strength at early stages (1 day) and even at 28 days, approaching the rheological properties of Portland cement type CEM 2, while simultaneously reducing the carbon footprint of the resulting building material.

[0008] The present invention aims to overcome the drawbacks of the prior art. In particular, the present invention aims to propose a low-carbon construction adhesive having an improved carbon footprint and an improved energy balance compared to prior art construction adhesives, while ensuring compressive strength and rheological properties close to those of CEM2 type Portland cement.

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

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

[0011] The present invention particularly relates to a construction adhesive comprising:

[0012] - 35% to 65% by weight of clinker,

[0013] - 5% to 30% by weight of a calcined clay matrix,

[0014] - 5% to 30% by weight of a raw clay matrix, and

[0015] - 0.05 to 5% by weight of a deflocculant;

[0016] And wherein the mass ratio of the raw clay matrix to the calcined clay matrix is ​​0.2 to 7.

[0017] Compared to conventional LC3-type construction binders, the combination of raw clay and partially substituted calcined clay allows for a reduction in the carbon footprint, primarily by limiting the amount of calcined components required (e.g., CEM 1 cement or calcined clay matrix), and by reducing the energy input required to form the building material. Furthermore, the construction binder according to the invention ensures the retention of a young-age compressive strength of greater than 5 MPa and improves the rheological properties of the construction binder in the fresh state.

[0018] According to other optional features, the construction adhesive according to the invention may comprise the following features, taken alone or in combination:

[0019] - Up to 25% by weight of precursors.

[0020] - The precursor comprises a source of calcium carbonate.

[0021] - Precursors are selected from the group consisting of: blast furnace slag, fly ash, silica fumes, natural or synthetic limestone fillers, siliceous fillers, diatomaceous earth.

[0022] - Calcium carbonate has a D50 comprised between 0.1 and 5 microns.

[0023] - Calcium carbonate contains vaterite.

[0024] - Deflocculants are organic deflocculants.

[0025] - The clay matrix has a D50 approximately equal to 10 μm.

[0026] - 35% by weight of clinker.

[0027] - Up to 65% by weight of clinker.

[0028] - 35% to 50% by weight of clinker.

[0029] - 20% by weight of precursor.

[0030] - 15 to 20% by weight of precursors.

[0031] - 5% by weight of a calcined clay matrix.

[0032] - At least 10% by weight of a raw clay matrix.

[0033] - At least 30% by weight of a raw clay matrix.

[0034] - Calcined clay matrix is ​​a flashed clay matrix.

[0035] - The calcined clay matrix is ​​a natural volcanic ash rock.

[0036] - The calcined clay matrix is ​​metakaolin.

[0037] - The construction adhesive comprises at least:

[0038] o 40% to 55% by weight of clinker,

[0039] o up to 25% by weight of precursors,

[0040] o 5% to 15% by weight of a calcined clay matrix,

[0041] o 15% to 30% by weight of a raw clay matrix, and

[0042] o 0.05% to 2% by weight of a deflocculant;

[0043] The mass ratio of the raw clay matrix to the calcined clay matrix is ​​0.5-6.

[0044] - The construction adhesive comprises at least:

[0045] o 39% by weight of clinker,

[0046] o 20 wt% of precursor,

[0047] o 10% by weight of a calcined clay matrix,

[0048] o 30% by weight of a raw clay matrix, and

[0049] o 1 wt% deflocculant.

[0050] - The construction adhesive comprises:

[0051] o 39% by weight of clinker,

[0052] o 20 wt% of precursor,

[0053] o 20% by weight of a calcined clay matrix,

[0054] o 20% by weight of a raw clay matrix, and

[0055] o 1 wt% deflocculant.

[0056] According to a second object, the present invention also relates to a construction material comprising the construction adhesive according to the invention. DETAILED DESCRIPTION

[0057] Other characteristics and advantages of the invention will be better understood on reading the following description and with reference to the accompanying drawings, given by way of illustration and non-limiting nature.

[0058] In the following, an overview and related terms of the present invention are described before presenting the disadvantages of the prior art, and finally it is shown in more detail how the present invention overcomes these disadvantages.

[0059] Throughout the remainder of this specification, the term "by weight" in relation to construction adhesives must be understood as referring to the dry weight of the construction adhesive. The dry weight corresponds to the weight before the addition of water (e.g., necessary to form the construction material). When weight % values ​​are given as intervals, the extreme values ​​are included.

[0060] Within the meaning of the present invention, the expression "clay matrix" may correspond to one or more rock materials based on phyllosilicates, hydrated silicates or aluminosilicates having a layered structure, said clay matrix being at least partially composed of fine particles, which generally originate from the modification of silicates having a three-dimensional framework or from the precipitation of supersaturated fluids. The clay matrix may thus include a mixture of such rock materials, which may, for example, include kaolinite, serpentine, pyrophyllite, talc, montmorillonite, vermiculite, illite, glauconite, mica, chlorite, palygorskite, sepiolite, intercalated materials or mixtures thereof (Alain Meunier. Clays, 2005). Furthermore, the clay matrix may include loam or silt sand. The clay matrix may be derived from, but is not limited to, construction site spoil, quarry fines, clay-limestone fines, wash fines, clay sludge, stripping material, clayey excavation material such as excavated soil, or sediments including dredged sediments and shale muds, phyllosilicate rocks and alterites such as turbidites, marls, argillaceous rocks, wrinkle rocks, laterites, schists, and mica schists.

[0061] "Concrete" refers to a mixture of aggregate (possibly sand) with a construction binder (e.g. cement) and water, which has set. The term concrete can therefore correspond to a construction element formed from a mixture of aggregate, mineral or vegetable, possibly sand, one or more additives, a construction binder and water.

[0062] The expression "raw clay matrix" within the meaning of the present invention corresponds to a clay matrix that has not undergone a calcination step. In particular, that is to say, it has not undergone any previous heat treatment. For example, this corresponds to a clay matrix that has not undergone a temperature increase of more than 300° C., preferably more than 200° C., and more preferably more than 150° C. In practice, the raw clay matrix may have undergone a drying step, which requires a temperature increase generally substantially equal to or less than 150° C., but without a calcination step. The raw clay matrix may preferably comprise a rock material, which may, for example, comprise kaolinite, serpentine, pyrophyllite, talc, montmorillonite, vermiculite, illite, glauconite, mica, chlorite, palygorskite, sepiolite, intercalated rock, or mixtures thereof.

[0063] For the purposes of the present invention, a "deflocculating agent," "deflocculant," or "deflocculation agent" may correspond to a compound capable of dissociating aggregates and colloids, particularly in aqueous suspension. For example, deflocculants have been used in the context of drilling or oil extraction to make clays more mobile and facilitate extraction or drilling.

[0064] Within the meaning of the present invention, the term "binder" or "construction binder" is understood to mean a formulation that ensures the agglomeration of materials, in particular during the setting period, which then allows the building material to harden. Thus, it particularly ensures the agglomeration of sand and other aggregates with the binder's components. The binder according to the invention is especially a hydraulic binder, meaning that it hardens upon contact with water.

[0065] The term "Portland cement" refers to a hydraulic binder composed primarily of hydraulic calcium silicates that sets and hardens by chemical reaction with water. Portland cement typically contains at least 95% clinker and up to 5% of minor components, such as alkalis (Na2O, K2O), magnesium oxide (MgO), gypsum (CaSO4·2H2O), or trace amounts of various metals.

[0066] Within the meaning of the present invention, the expression "metal oxide" may refer to a composition comprising a metal oxide, such as an aluminate. In particular, the construction adhesive according to the present invention may comprise a metal oxide composition comprising greater than 25% by weight of metal oxide, preferably greater than 30% by weight of metal oxide, more preferably greater than 40% by weight of metal oxide, and even more preferably greater than 45% by weight of metal oxide. For example, the metal oxide composition comprises greater than 2% by weight of aluminate, preferably greater than 5% by weight of aluminate, more preferably greater than 7% by weight of aluminate, and even more preferably greater than 10% by weight of aluminate. Furthermore, the metal oxide may correspond to or comprise an alkaline earth metal oxide. For example, the metal oxide composition may comprise greater than 10% by weight of calcium oxide, preferably greater than 20% by weight of calcium oxide, more preferably greater than 25% by weight of calcium oxide, and even more preferably greater than 30% by dry weight of calcium oxide. The metal oxide composition may include chemical substances other than metal oxides. For example, the metal oxide composition can be replaced by aluminum or silicon oxide, e.g., greater than 10% by weight of aluminum or silicon oxide, preferably greater than 20% by weight of aluminum or silicon oxide, more preferably greater than 25% by weight of aluminum or silicon oxide, and even more preferably greater than 30% by weight of aluminum or silicon oxide. These mass concentrations can be readily measured 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 comprising greater than 50%, preferably greater than 70%, more preferably greater than 80%, and even more preferably greater than 90% of metal oxide and / or aluminum or silicon oxide (including aluminates). Preferably, the metal oxide composition will correspond to a slag from metallurgy, such as blast furnace slag or fly ash. The "metal oxide" composition is preferably a calcined metal oxide composition. That is, it has undergone a high-temperature step. This high-temperature step can be natural or artificial; in this case, it is a high-temperature treatment. The high temperature step may, for example, correspond to a treatment at a temperature greater than or equal to 400° C., preferably greater than or equal to 750° C. and more preferably greater than or equal to 900° C., and even more preferably greater than 1000° C. The 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 29581-2:20 10).

[0067] Within the meaning of the present invention, the term "substantially equal to" corresponds to a value which varies by less than 20%, preferably by less than 10%, even more preferably by less than 5% with respect to a comparative value.

[0068] The term "clinker" or "Portland clinker" refers to the constituents of cement and is derived from the firing of a mixture consisting of approximately 80% limestone and 20% aluminosilicates (e.g., clay). This firing, or slaking, is typically carried out at temperatures exceeding 1200°C, which is extremely energy-intensive and produces high greenhouse gas emissions. The clinker is typically ground and then 5% gypsum, anhydrite, and / or calcined gypsum is added to produce CEM1 Portland cement.

[0069] The term "D50" refers to the median diameter at which 50% (by volume or mass, preferably by volume) of the grains, particles, aggregates (aggregates), or sediments are smaller than a given diameter. For example, if sieving and sedimentation analysis methods indicate D50 = 5.8 mm, then 50% of the particles in the sample (by volume or mass, preferably by volume) are larger than 5.8 mm, and 50% are smaller than 5.8 mm. D50 is generally used to indicate the particle size of a group of particles. D50 can be measured by any method known to those skilled in the art, preferably according to ASTM D422-63, XP P 94-041 (1995), NF ISO 11277 (2020), NF EN ISO 17892-4 (2018), or ASTM D6913-04 (2009), or, in particular, ISO 13320:2020 for fine particles (e.g., D10 or <65 μm).

[0070] The construction industry must gradually optimize productivity while addressing social and environmental challenges. In this context, research laboratories 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 significant amounts of Portland clinker and / or calcined components.

[0071] In fact, even when the construction binder does not contain Portland clinker, the latter still represents almost 50% by weight of the construction binder in the calcined fraction and has the disadvantage of not having a mechanical resistance comparable to that of Portland cements of the CEM1 or CEM2 type.

[0072] However, it is urgent 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 with a lower or even zero carbon footprint. To address this problem, the present inventors have developed a construction adhesive comprising clinker, raw and calcined clay matrices in specific ratios, which allows reducing the amount of clinker and calcined clay matrices compared to construction adhesives containing clinker and / or calcined components, while having a mechanical strength of at least 5 MPa, preferably 10 MPa at 1 day and a mechanical strength of at least 30 MPa, preferably 40 MPa at 28 days.

[0073] Therefore, the present invention particularly relates to a low-carbon construction adhesive comprising clinker, a calcined clay matrix, a raw clay matrix, and a deflocculant, wherein the mass ratio of the raw clay matrix to the calcined clay matrix is ​​0.2 to 7.

[0074] The construction adhesive according to the invention can be prepared extemporaneously or at the production site and then possibly stored and transported to the construction site.

[0075] The general and preferred characteristics of each ingredient of the formulation according to the invention will be presented in detail.

[0076] Raw clay matrix

[0077] The raw clay matrix may, for example, include at least one mineral substance selected from the group consisting of illite, kaolinite, montmorillonite, vermiculite, chlorite, montmorillonite, muscovite, halloysite, sepiolite, and palygorskite.

[0078] Preferably, the raw clay matrix comprises at least two types of clay selected from the group consisting of illite, kaolinite, montmorillonite, vermiculite, chlorite, montmorillonite, muscovite, halloysite, sepiolite, intercalated clay, pyrophyllite, talc, serpentine, and palygorskite. This includes clays known as intercalated clays, which are complex combinations of several clays. Even more preferably, the raw clay matrix comprises at least one mineral substance selected from the group consisting of kaolinite, illite, montmorillonite, palygorskite, sepiolite, chlorite, montmorillonite, and vermiculite.

[0079] Table 1 below presents the chemical characteristics of these mineral substances.

[0080] [Table 1]

[0081]

[0082] In addition, the raw clay matrix may also contain montmorillonite and / or clays known as intercalated clays, which are complex combinations (at the atomic scale) of several clays.

[0083] The type of clay can be determined by methods known to those skilled in the art. In particular, X-ray diffraction can be used after a specific sample preparation method known as the directional blade method (see Thiry et al., 2013, "Technique for the preparation of X-ray diffraction analysis and introduction to the schemes of diffraction"). For example, the following conditions can be used:

[0084] Equipment: Diffractometer, e.g., BRUKER D8 ADVANCE (Bragg-Brentano geometry); e.g., with the following settings: copper tube (λkα1≈1.54Å), generator power: 40 kV, 40 mA; primary optics: 0.16° fixed slit; secondary optics: 2.5° Soller slit; LynXeye XE-T detector

[0085] Acquisition parameters: scanning from 4° 2θ to 70° 2θ; scanning speed of 0.03° 2θ / second, counting time: 20 minutes to 60 minutes per step; rotating sample.

[0086] The raw clay matrix may preferably correspond at least partially to excavated clay soil, preferably uncalcined excavated clay soil, such as processed raw excavated clay soil. The raw clay matrix may advantageously have been treated, the treatment being selected from the group consisting of: grinding, sorting, screening and / or drying. Preferably, the raw clay matrix used in the binder has been ground.

[0087] Preferably, the construction adhesive according to the invention comprises at least 5% by weight of a raw clay matrix, more preferably at least 15% by weight of a raw clay matrix. In fact, the construction adhesive according to the invention has the advantage of being able to include a large amount of raw clay matrix without changing the mechanical properties of the building material.

[0088] Furthermore, preferably, the construction adhesive according to the invention comprises at most 30% by weight of a raw clay matrix, more preferably at most 25% by weight of a raw clay matrix.

[0089] Thus, in particular, the construction adhesive according to the invention comprises 5 to 30% by weight of a raw clay matrix, preferably 10 to 28% by weight or 15 to 27% by weight of a raw clay matrix, more preferably 20 to 26% by weight of a raw clay matrix, and even more preferably 22 to 25% by weight of a raw clay matrix.

[0090] Advantageously, the raw clay matrix may comprise pulverized raw clay.Preferably, the raw clay matrix may have a D50 of less than or equal to 500 μm, preferably less than or equal to 250 μm, more preferably less than or equal to 100 μm or even more preferably less than or equal to 50 μm.

[0091] Furthermore, the raw clay matrix may have a D50 greater than or equal to 0.1 μm, preferably greater than or equal to 1 μm, more preferably greater than or equal to 10 μm or even more preferably greater than or equal to 20 μm, more preferably greater than 40 μm. This allows limiting the constraints on industrial production tools dedicated to grinding.

[0092] More preferably, the raw clay matrix may have a D50 of 10 to 500 μm, preferably 15 to 250 μm, more preferably 20 to 150 μm or even more preferably 20 to 50 μm. The presence of clay ground to such diameters may allow improving the properties of the construction adhesives and building materials according to the invention.

[0093] Advantageously, the raw clay matrix may comprise at least 2% by weight of loam particles, preferably at least 4% by weight, more preferably at least 6% by weight. For example, the raw clay matrix may comprise up to 50% by weight of loam particles, preferably up to 30% by weight, more preferably up to 20% by weight. For example, the raw clay matrix may comprise from 2% to 50% by weight of loam particles, preferably from 4% to 30% by weight, more preferably from 6% to 20% by weight. The loam particles are in particular particles having a diameter comprised between 2 μm and 63 μm.

[0094] The raw clay matrix may comprise at least 1% by weight of sand, preferably at least 2% by weight, more preferably at least 3% by weight. For example, the raw clay matrix may comprise up to 70% by weight of sand, preferably up to 50% by weight, more preferably up to 40% by weight. For example, the raw clay matrix may comprise from 1% to 70% by weight of sand particles, preferably from 2% to 50% by weight, more preferably from 3% to 40% by weight. Sand particularly corresponds to particles having a diameter between 63 μm and 2 mm.

[0095] Preferably, the raw clay matrix comprises a mineralogical clay content 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, mineralogically raw clay matrices comprising a low clay content may be used. In particular, the raw clay matrix may correspond to fine clay-limestone or clay-silica / quartz particles comprising 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.

[0096] Calcined clay matrix

[0097] The calcined clay matrix may be a green clay material that has previously undergone a heat treatment, preferably at a temperature of at least 450°C and at most 900°C, or in a flash calcination process at a temperature between 800°C and 1100°C.

[0098] Preferably, the calcined clay material is dehydroxylated to an amorphous material while preventing the formation of high temperature aluminosilicate crystalline phases such as mullite.

[0099] The calcined clay matrix is ​​preferably amorphous and has pozzolanic activity.

[0100] In addition, the calcined clay matrix may comprise 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, even more preferably at least 30% by weight of metal oxide. The calcined clay matrix may further comprise up to 70% by weight of metal oxide, preferably up to 60% by weight of metal oxide.

[0101] The calcined clay matrix can be formed using all of the clay matrices mentioned above. The calcined clay matrix may include, as a non-limiting example, at least one mineral substance selected from metakaolin, metaillite, and / or metamontmorillonite. Preferably, the calcined clay matrix comprises kaolinite and / or illite. Therefore, preferably, the calcined clay matrix corresponds to metakaolin or metaillite.

[0102] According to a preferred embodiment of the present invention, the calcined clay matrix consists of metakaolin. Metakaolin is a material resulting from the calcination of kaolinite or a kaolinite-rich mineral, e.g. having a kaolinite content of at least 20 wt%, preferably at least 25 wt%, even more preferably at least 30 wt%.

[0103] Preferably the calcined clay matrix is ​​a flash clay matrix, such as metakaolin from flash calcination.

[0104] Alternatively, the calcined clay matrix may be derived from natural pozzolana, i.e. formed from volcanic basalt outcrops or of similar composition, or more generally from any material having "pozzolanic properties", i.e. having the ability to combine with lime or portlandite at room temperature and in the presence of water to produce very slightly soluble hydrates.

[0105] Preferably, the construction adhesive according to the invention comprises at least 5% by weight of a calcined clay matrix, more preferably at least 15% by weight of a calcined clay matrix. In fact, the construction adhesive according to the invention has the advantage of being able to include small amounts of raw clay matrix without altering the mechanical properties of the construction material.

[0106] Furthermore, preferably, the construction adhesive according to the present invention comprises at most 30% by weight of a calcined clay matrix, more preferably at most 25% by weight of a calcined clay matrix.

[0107] Thus, in particular, the construction adhesive according to the present invention comprises 5 to 30 wt.-% of a calcined clay matrix, preferably 10 to 25 wt.-% or 10 to 20 wt.-% of a calcined clay matrix, more preferably 12.5 to 20 wt.-% of a calcined clay matrix, and even more preferably 12.5 to 15 wt.-% of a calcined clay matrix.

[0108] Optimized mass ratio

[0109] As shown in the examples, the Applicant has found that certain mass ratios between the raw clay matrix and the calcined clay matrix of the construction binder make it possible to obtain advantageous mechanical resistance properties both at young age and at 28 days.

[0110] Advantageously, in the construction adhesive according to the invention, the calcined clay matrix and the raw clay matrix are present in such amounts that the mass ratio by weight of the raw clay matrix to the calcined clay matrix is ​​between 0.33 and 3 (inclusive). In fact, as shown in the examples, such a mass ratio allows a high Rc (e.g., greater than 7 MPa) to be obtained at 1 d, while maintaining an Rc of at least 30 MPa at 28 d.

[0111] Deflocculants

[0112] Many compounds can act as deflocculants, and many are generally known to those skilled in the art.

[0113] The presence of one or more deflocculants may improve the properties of the material formed from the construction binder.

[0114] In the context of the present invention, the construction adhesive may comprise an organic deflocculant, advantageously a deflocculant polymer.According to the present invention, the organic deflocculant comprises at least one carbon atom and preferably at least one carbon-oxygen bond.

[0115] The anti-flocculating polymer may be a nonionic surfactant, such as polyoxyethylene ether. The polyoxyethylene ether may be selected from lauryl poly(oxyethylene) ether.

[0116] The deflocculating polymer may also be an anionic agent, such as an anionic surfactant. In particular, the anionic agent may be selected from the group consisting of alkylarylsulfonates, amino alcohols, carbonates, silicates, fatty acids, humates (e.g., sodium humate), carboxylic acids, ligninsulfonates (e.g., sodium ligninsulfonate), polyacrylates, phosphates or polyphosphates such as sodium hexametaphosphate, sodium tripolyphosphate, sodium orthophosphate, carboxymethylcellulose, and mixtures thereof.

[0117] The deflocculating polymer may also be a polyacrylate. It may then, for example, be chosen from sodium polyacrylate and ammonium polyacrylate.

[0118] The deflocculating polymer may also be an amine selected, for example, from the group consisting of 2-amino-2-methyl-1-propanol; mono-, di- or triethanolamine, isopropanolamine (1-amino-2-propanol, diisopropanolamine, triisopropanolamine) and N-alkylethanolamines.

[0119] Preferably, the deflocculating polymer is selected from the group consisting of lignin sulfonates (eg sodium lignin sulfonate), polyacrylates, humates and mixtures thereof.

[0120] Preferably, the deflocculating polymer is selected from the group consisting of lignin sulfonates (such as sodium lignin sulfonate), polyacrylates, humates, polycarboxylates (such as ether polycarboxylates) and mixtures thereof.

[0121] More preferably, the deflocculating polymer comprises humates, lignin sulfonates and / or polyacrylates.

[0122] The deflocculant may also be a silicate, such as sodium silicate, sodium metasilicate or sodium trisilicate.

[0123] Alternatively, the deflocculant may be a mixture of compounds, for example a mixture comprising at least two compounds selected from the group consisting of nonionic surfactants, anionic agents, polyacrylates, amines and organophosphorus compounds.

[0124] In particular, the deflocculant may be a mixture of sodium silicate and sodium carbonate.

[0125] The deflocculant is preferably in the form of a salt.

[0126] However, the present invention is not limited to the above-mentioned deflocculants; any type of deflocculant known to those skilled in the art may be used instead of the above-mentioned deflocculants.

[0127] The deflocculants usable according to the invention may be in solid or liquid form.

[0128] In particular, the deflocculant constitutes at least 0.05 wt % of the construction adhesive, preferably at least 0.1 wt % of the construction adhesive, preferably at least 0.25 wt % of the construction adhesive, more preferably at least 0.5 wt % of the construction adhesive, more preferably at least 0.5 wt % of the construction adhesive, even more preferably at least 0.8 wt % of the construction adhesive, and for example at least 1 wt % of the construction adhesive.

[0129] Furthermore, the deflocculant represents at most 5% by weight of the construction adhesive, preferably at most 4% by weight of the construction adhesive, more preferably at most 3% by weight of the construction adhesive, and even more preferably at most 2% by weight of the construction adhesive. In practice, excessively high concentrations are not necessary to form a material with advantageous mechanical properties.

[0130] In particular, the deflocculant comprises 0.05 wt % to 5 wt % of the construction adhesive, preferably 0.1 wt % to 4 wt % of the construction adhesive, more preferably 0.25 wt % to 3 wt % of the construction adhesive, even more preferably 0.5 wt % to 2 wt % of the construction adhesive, and even more preferably 0.8 wt % to 2 wt % of the construction adhesive, and even more preferably 0.9 wt % to 2 wt % of the construction adhesive.

[0131] Precursor

[0132] The construction adhesive according to the present invention may contain a precursor. Without being limited by theory, the role of the precursor is to contribute to the mechanical strength of the construction material.

[0133] The precursor may comprise a carbonate source in combination with or without a silicate. In particular, the precursor may comprise sodium carbonate or potassium carbonate. Sodium carbonate or potassium carbonate may also be mixed with sodium silicate or potassium silicate.

[0134] Preferably, the precursor may comprise a calcium carbonate source. The calcium carbonate source may correspond to a solid material consisting mainly of carbonate minerals such as calcite or dolomite minerals.

[0135] As illustrative examples, the source of the carbonate may be limestone, dolomite, chalk, aragonite, or vaterite.

[0136] Alternatively, the limestone may also be magnesium carbonate and / or a mixture of magnesium carbonate and dolomite.

[0137] Preferably, the limestone is natural limestone consisting primarily of calcium carbonate, having various polymorphs such as calcite and / or aragonite, but also containing some magnesium carbonate and / or dolomite.The limestone may also be clayey limestone or natural marl.

[0138] Additionally, the precursor may include a siliceous filler or "quartz powder." For example, the siliceous filler may include micronized silica and kaolinite.

[0139] The precursor may also comprise calcined schist, diatomaceous earth, phonolite, paper mill sludge ash, or cullet.

[0140] Additionally, the precursor may comprise at least 30 wt% calcium oxide or at least 30 wt% calcium carbonate.

[0141] Alternatively or additionally, the precursor may further comprise blast furnace slag, fly ash, incineration ash, pozzolan, silica fume, limestone filler (eg, micronized limestone filler of known types), or combinations thereof.

[0142] The precursor may also have a specific particle size, such as D50, which characterizes the particle size at which 50% of the volume (or mass) of the precursor has a particle size less than 25 microns and 50% of the volume (or mass) of the precursor has a particle size greater than 5 microns. Alternatively, the precursor may have a specific particle size, such as an average particle size characterizing the average diameter of the particles being between 5 microns and 50% of the volume (or mass) of the precursor having a particle size greater than 5 microns.

[0143] Alternatively, the precursor (eg, calcium carbonate) may have a specific particle size, such as characterized by an average particle size of 0.1 micrometers to 100 micrometers, preferably 0.1 micrometers to 5 micrometers.

[0144] When the precursor is calcium carbonate, it may be made from vaterite.

[0145] Calcium carbonate can therefore comprise at least 10% by weight of vaterite; or at least 20% by weight of vaterite; or at least 30% by weight of vaterite; or at least 40% by weight of vaterite; or at least 50% by weight of vaterite; or at least 60% by weight of vaterite; or at least 70% by weight of vaterite; or at least 80% by weight of vaterite; or at least 90% by weight of vaterite; or at least 95% by weight of vaterite; or at least 99% by weight of vaterite.

[0146] Vaterite forms aragonite in the presence of water. Vaterite can be obtained by any method known to those skilled in the art.

[0147] In the present invention, when the precursor is present, its content may be at least 1 wt % of the construction adhesive, preferably at least 10 wt % of the construction adhesive, even more preferably at least 15 wt % of the construction adhesive.

[0148] Furthermore, preferably, the construction adhesive according to the invention comprises at most 25% by weight of precursors, more preferably at most 20% by weight of precursors.

[0149] Thus, in particular, the construction adhesive according to the invention may comprise from 1% to 25% by weight of precursors, preferably from 10% to 25% by weight of precursors, more preferably from 15% to 20% by weight of precursors.

[0150] clinker

[0151] The construction adhesive according to the invention also comprises clinker.

[0152] Clinker is obtained by firing a mixture consisting of approximately 80% limestone and 20% aluminosilicates. This firing, known as slaking, is typically carried out at temperatures exceeding 1200°C. As previously mentioned, clinker may also contain 5% gypsum. The function of gypsum is to provide sulfates that slow the setting of cement. Although gypsum is typically used in addition to Portland clinker to form CEM 1, any other component that will provide sulfates and slow the setting of cement, such as calcined gypsum or anhydrite, may be used in addition to or in place of gypsum.

[0153] As a non-limiting example, the clinker may be "Portland" clinker. Portland clinker is composed of at least two-thirds by mass of calcium silicates (3CaO·SiO2:C3S and 2CaO·SiO2:C2S), with the remainder consisting of aluminum- and iron-containing phases, and free lime (CaO) not exceeding 2%. The mass ratio (CaO) / (SiO2) is typically greater than or equal to 2.

[0154] Preferably, the construction adhesive according to the invention comprises at least 35 wt. % clinker, more preferably at least 40 wt. % clinker.

[0155] Furthermore, preferably, the construction adhesive according to the invention comprises at most 60 wt. % clinker, more preferably at most 65 wt. % clinker.

[0156] Thus, in particular, the construction adhesive according to the invention comprises 35 to 65 wt. % clinker, preferably 40 to 60 wt. % or 45 to 60 wt. % clinker, more preferably 45 to 55 wt. % clinker, and even more preferably 45 to 50 wt. % clinker.

[0157] In a particular embodiment, the construction adhesive according to the invention comprises:

[0158] - 40% to 55% by weight of clinker,

[0159] - 15 to 25% by weight of precursors,

[0160] - 5% to 15% by weight of a calcined clay matrix,

[0161] - 15% to 30% by weight of a raw clay matrix, and

[0162] - 0.05 to 2% by weight of a deflocculant;

[0163] The mass ratio of the raw clay matrix to the raw clay matrix is ​​0.2 to 7.

[0164] In another particular embodiment, the construction adhesive according to the invention comprises:

[0165] - 39% by weight of clinker,

[0166] - 20% by weight of a precursor, preferably a limestone filler,

[0167] - 10% by weight of a calcined clay matrix,

[0168] - 30% by weight of a raw clay matrix, and

[0169] - 1% by weight of a deflocculant.

[0170] In another particular embodiment, the construction adhesive according to the invention comprises:

[0171] - 39% by weight of clinker,

[0172] - 20% by weight of a precursor, preferably a limestone filler,

[0173] - 20% by weight of a calcined clay matrix,

[0174] - 20% by weight of a raw clay matrix, and

[0175] - 1% by weight of a deflocculant.

[0176] In another particular embodiment, the construction adhesive according to the invention comprises:

[0177] - 39% by weight of clinker,

[0178] - 20% by weight of a precursor, preferably a limestone filler,

[0179] - 25% by weight of a calcined clay matrix,

[0180] - 5% by weight of a raw clay matrix, and

[0181] - 1% by weight of a deflocculant.

[0182] In another embodiment, the construction adhesive of the present invention comprises:

[0183] - 50% by weight of clinker,

[0184] - 30% by weight of a calcined clay matrix,

[0185] - 20% by weight of a raw clay matrix, and

[0186] - 1% by weight of a deflocculant.

[0187] Therefore, according to another aspect, the present invention relates to a building material formed from the low carbon building binder according to the present invention.

[0188] The low-carbon construction binder according to the invention allows, in particular, the production of insulating building materials: lightweight aggregates of the "vegetable or porous" type added to the construction binder according to the invention; lightweight concrete: from the construction binder according to the invention with the addition of a foaming agent, such as aluminum powder. This allows air to be trapped in the material and improves its insulating properties; prefabricated elements: concrete blocks or panels produced in a factory with the construction binder according to the invention; and insulating modules.

[0189] Example:

[0190] Preparation of construction adhesive:

[0191] In all the examples given below, the construction adhesives of the present invention were prepared according to the same protocol, namely, a dry mixture was prepared between predetermined amounts of clinker, raw clay matrix, calcined clay matrix, precursor (except for one example in which the precursor was not present), and deflocculant, followed by the addition of water and the mixing of the solution at a low speed, i.e., substantially 100 revolutions per minute, for 90 seconds. Water and aggregate were then added to the construction adhesive and mixed at a low speed, i.e., substantially 100 revolutions per minute, for 45 seconds to obtain a construction material.

[0192] Alternatively, dry mixing may be achieved by first mixing the green clay base, the calcined clay base and the deflocculant and then adding the clinker and precursor (if present) in a second step.

[0193] The mass ratio of water to the dry matter of the composition (also referred to as the construction binder) is adjusted to a value between 0.4 and 0.6. In one embodiment, the construction material, mortar, comprises 25% by weight of binder and 75% by weight of sand; this mixture is supplemented with water, and the mass ratio of water to the dry matter of the binder is adjusted to a value of 0.4.

[0194] The mortar based on the construction adhesive thus formed was then poured into two separate moulds and cured at room temperature, ie at about 20 degrees Celsius for 24 hours for the first mould and at 20°C for 28 days in water for the second mould.

[0195] Alternatively, the mortar can be poured into a mold and then allowed to mature in a curing step for less than 24 hours at room temperature (i.e., about 25 degrees Celsius) or preferably under heat treatment. During this curing step, the mold can be sealed or the top layer of the building material can be covered with a curing compound to limit / prevent evaporation.

[0196] Method for measuring the consistency of construction adhesives:

[0197] Once the ingredients 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.

[0198] Methods for measuring the mechanical properties of construction adhesives:

[0199] Once curing is complete, the mechanical resistance is measured.The mechanical resistance of a construction adhesive is its compressive strength, measured according to standard NF EN 196-1 for a prism with a side length of 40 mm and a length of 160 mm, and expressed in megapascals (MPa).

[0200] Comparison of the construction adhesive according to the invention with known construction adhesives:

[0201] Table 2 below shows different types of known construction adhesives. The mass of the components associated with each formulation is expressed as a percentage of the total mass (dry weight) of the construction adhesive.

[0202] [Table 2]

[0203]

[0204] Table 2 thus presents the mechanical resistance of known construction adhesives (adhesives CEM2, LC3, REF1 and REF2), but which do not form part of the present invention, such as a construction adhesive of type CEM2, better known under the name of Portland limestone cement, which has a compressive strength of the order of 50 MPa.

[0205] The LC3 formulation can be obtained by following the teachings of patent EP 2429966. This LC3 construction adhesive contains 30% by weight of metakaolin obtained by calcining kaolin, 50% by weight of CEM 1, and 20% of limestone filler. Consequently, the mechanical resistance of this construction adhesive, at approximately 45 MPa, approaches that of a CEM 2 construction adhesive.

[0206] Finally, construction adhesives REF1 and REF2 were obtained by following the teachings of patent application EP2429966, but by replacing all or part of the calcined clay matrix with a raw clay matrix. These tests showed that when the construction adhesive did not contain a calcined clay matrix (REF1), the mechanical strength dropped sharply (12 MPa), and when the construction adhesive contained equal proportions of raw and calcined clay matrices, the mechanical strength was higher (25 MPa) (REF2), but much lower than references CEM2 and LC3. Therefore, the absence of a calcined clay matrix or its presence in equal proportions with the raw clay matrix did not allow the production of concrete with adequate mechanical properties.

[0207] Table 3 below shows different types of construction adhesives according to the invention (MTU01 to MTU05). The mass of the components associated with each formulation is expressed as a percentage of the total mass (dry weight) of the construction adhesive. The construction adhesives listed below differ particularly in the more or less significant ratios of raw clay and calcined clay matrix; one of the examples of the construction adhesive also contains blast furnace slag as a precursor.

[0208] [Table 3]

[0209]

[0210] As shown in Table 3, the compressive strength of the construction adhesives according to the present invention is equal to or even higher than that achieved with concrete formed with CEM2 or LC3 cement. Thus, the present invention allows the formation of low-carbon construction adhesives by further limiting the proportions of clinker and calcined clay matrix used. This, in turn, allows the carbon footprint and energy balance of these construction adhesives to be further reduced compared to low-carbon binders of the CEM2 and LC3 types, making them suitable construction materials that meet most of the industry's needs. Finally, the construction adhesives of the present invention offer the advantages of improved rheological properties compared to reference construction adhesives containing calcined and / or raw clay matrices, as well as early compressive strength, which allows them to be used to form any type of construction material, such as thin (less than 200 mm thick) or thick tiles, and more generally for masonry work, in reinforced or prestressed concrete of any nature.

Claims

1. A construction adhesive 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 deflocculant; And wherein the mass ratio of the raw clay matrix to the calcined clay matrix is ​​0.2 to 7.

2. The construction adhesive of claim 1 , further comprising up to 25% by weight of a precursor.

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

4. The construction adhesive according to claim 2 or 3, wherein the precursor is selected from the group consisting of blast furnace slag, fly ash, silica fume, natural or synthetic limestone filler, siliceous filler, diatomaceous earth.

5. The construction adhesive according to claim 3 or one of claims 3 and 4, wherein the calcium carbonate has a D50 comprised between 0.1 μm and 5 μm.

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

7. The construction adhesive according to any one of claims 1 to 6, wherein the deflocculant is an organic deflocculant.

8. Construction adhesive according to any one of claims 1 to 7, wherein the raw clay matrix has a D50 substantially equal to 10 μm.

9. A construction adhesive according to any one of claims 1 to 8, comprising between 35% and 50% by weight of clinker.

10. A construction adhesive according to any one of claims 1 to 9 comprising at least 10% by weight of a raw clay matrix.

11. A construction adhesive according to any one of claims 1 to 9 comprising at least 30% by weight of a raw clay matrix.

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

13. The construction adhesive according to any one of claims 1 to 9, comprising at least: - 40% to 55% by weight of clinker, - up to 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 a deflocculant; And wherein the mass ratio of the raw clay matrix to the calcined clay matrix is ​​0.5 to 6.

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

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

16. A building material comprising the building adhesive according to any one of claims 1 to 15.

Images