Reactive supplementary cementitious materials containing phyllosilicate and method for preparing the same

Abstract

The present disclosure relates to a process for preparing a pozzolanic material comprising the following steps: S1: providing a raw material RM component comprising: - a phyllosilicate RM1, and, - at least one mineral compound RM2 different from RM1, S2: grinding said raw material provided at step S1 leading to said pozzolanic material PM, wherein said grinding step S2 is performed by providing an energy collision and / or a density of collisions in a quantity more than the activation energy of RM, wherein the raw material RM is continuously at a temperature lower than or equal to 200°C, preferably lower than or equal to 150°C.

Description

DescriptionTitle: Reactive supplementary cementitious materials containing phyllosilicate and method for preparing the sameTechnical Field

[0001] This disclosure pertains to the general field of hydraulic binder compositions comprising supplementary cementitious materials (SCM), for preparing building materials. In particular, the technical field of the invention relates to hydraulic mineral binders containing pozzolanic material, which are used in compositions able to set and harden, such as building materials.

[0002] More particularly, this disclosure is about a method for activating phyllosilicate, such as clays.Background Art

[0003] Portland cement production has a strong and negative impact on the environment due to the emissions of large quantities of carbon dioxide. The production of cement inherently generates CO2 during the calcination of the raw materials at very high temperature (1450°C) in a kiln through decarbonation of the limestone (Eq. (1)):CaCO3(s) — > CaO (s) + CO2(g) (Eq. (1))

[0004] In addition, carbon dioxide is released as a result of the combustion of the fossil fuels needed to heat the cement kiln. By adding the additional emissions of grinding, almost one ton of CO2 per ton of Portland cement is obtained. Overall, the cement industry is responsible for about 7 to 9% of the global carbon dioxide emissions.

[0005] Moreover, handling Portland cement may lead to health issues (such as allergy) due in particular to its high alkalinity (pH higher than 13). In addition, hazardous elements as hexavalent Chromium (Cr (VI)) may be released upon kneading, which is also unhealthy for the workers when it gets in contact with the skin. Although Cr (VI) reducing agents (as ferrous sulfate) are normally included in the cement powder, their efficiency is limited in time. Building workers, in particular those in the third world, are not expected to often check the deadline related to such treatments.

[0006] Most current research on new binders aims to replace Portland cement in various applications by binders with lower environmental impact. One route is through using resources without their expensive treatment, such as by-products from other industries (waste for one industry, but primary resource for others). This is the case of blast-furnace slag which is a by-product of iron industry. By grinding this product into fine powder (GGBS) one can obtain a cementitious material that can be used in partial substitution of cement or used alone by adding some chemical activators.

[0007] In particular, the applicant has already proposed to produce concrete and mortars specimens with low embedded carbon footprint, based on a combination of a supplementary cementitious materials, low content of clinker and high content of limestone filler. The supplementary cementitious material (SCM) utilized to manufacture such binders can be either (or a combination of)Ground Granulated Blast Furnace Slag, natural pozzolans, phyllosilicate like calcined clays, fly ash, silica fume, carbonated minerals.

[0008] Among these SCM, phyllosilicates, such as clays and clays bearing soils, are a natural resource very abundant all over the world, thus they represent a considerable resource of raw material. However, natural clays, or clay bearing soils, rarely display a pozzolanic behavior (i.e. sets when respectively mixed with water or a combination of lime source and water). Activation of clays is therefore generally necessary to confer them a pozzolanic behavior. Typically, the activation is performed through application of high temperature, also called calcination, in a rotary kiln, similarly to clinker manufacturing, or in a flash calciner. There, the temperature applied varies between 400°C and 1000°C, what has a negative impact to the environment.

[0009] Some efforts have been made to decrease the quantity of heat energy needed for calcinating clays. For instance, EP3909682A1 proposes a process of mechanochemical activation of a clays mixture) wherein the clays are ground in a mill at a temperature 300-1000°C with hot gas continuously flowed through the mill. As such the surface area of the clays is increased and the contact between the clays and hot gas is optimized. Although this process seems performant, it still needs an external source of heat energy.

[0010] In addition, when a clay comprises several types of phyllosilicates, it is quite difficult to activate all of them. Generally, a given phyllosilicate has a given range of calcination temperature.

[0011] Moreover, calcination is often preformed on clays presenting a high degree of purity.

[0012] It would be advantageous to develop a method for activating clays and clays bearing soils which demands less energy and is more ecofriendly than calcination and to enlarge the panel of phyllosilicate to be activated.

[0013] Hence, the present disclosure aims at reaching at least one of the following objectives: -O1- providing an alternative method for producing pozzolanic material from clays and other materials containing phyllosilicate,-02- providing a method for preparing a supplementary cementitious material from clays and other materials containing phyllosilicate without calcination needed,-03- providing a method for preparing a supplementary cementitious material from a combination of phyllosilicate at once,-04- providing a supplementary cementitious material which is at least as effective as calcined clays, -05- providing a hydraulic binder containing a reactive supplementary cementitious material obtained from clays and other materials containing phyllosilicate without calcination.-06- providing a new pozzolanic material issued from a raw material RM comprising:- a phyllosilicate RM1 , and,- at least one mineral compound RM2 different from RM1 .Summary

[0014] In this context it is proposed a process for preparing a pozzolanic material comprising the following steps:S1 : providing a raw material RM component comprising:- a phyllosilicate RM1 , and,- at least one mineral compound RM2 different from RM1 , and selected in the group comprising, preferably consisting of, waste glass, granulated blast furnace slag (GBS), steel slag, such as basic oxygen furnace (BOF) or electric arc furnace (EAF), ladle slag, reducing electric furnace (REF) or ground granulated blast furnace slag (GGBS), and mixtures thereof,S2: grinding said raw material provided at step S1 leading to said pozzolanic material PM, wherein said grinding step S2 is performed by providing an energy collision and / or a density of collisions in a quantity more than the activation energy of RM, at a temperature under calcination temperature of RM, wherein the whole process is performed at a temperature lower than or equal to 200°C, preferably lower than or equal to 150°C.

[0015] The disclosure also pertains to a pozzolanic material obtained by the process mentioned above.

[0016] The disclosure is also directed to a hydraulic binder comprising the pozzolanic material mentioned above.

[0017] The disclosure is further directed to a dry industrial mortar composition or dry concrete composition, comprising at least one aggregate and the hydraulic binder mentioned above.

[0018] In addition, the disclosure relates to a wet industrial mortar formulation or wet concrete formulation comprising at least one aggregate, the hydraulic binder mentioned above and water.

[0019] Moreover, the present disclosure is about a hardened industrial mortar product or hardened concrete product obtained from the wet industrial mortar formulation or wet concrete formulation mentioned above.

[0020] The disclosure is additionally drawn to a process for preparing the wet industrial mortar formulation or wet concrete formulation mentioned above comprising a step of mixing with water, at least one aggregate and the hydraulic binder mentioned above, the hydraulic binder being prepared before the mixing step or in situ during the mixing step from at least some of the different components of the hydraulic binder composition taken separately and / or under the form of premix(es).

[0021] According to the terminology of this text, the following non limitative definitions have to be taken into consideration:

[0022] “Pozzolanic material” is understood as meaning a powdery substance either from natural origin or derived from a treated natural resource. It refers more particularly to the type of materials that hardens by adding a mixture of water and a CaO source.

[0023] “binder” refers to “hydraulic binder” meaning any material that hardens just by adding water, like cement.

[0024] "cement" is understood as meaning a powdery substance made for use in making mortar or concrete. They are mineral binders, possibly free from any organic compound. It refers to any ordinary cement and it includes Ordinary Portland Cement, blends of Ordinary Portland Cement, Pozzolanic materials and / or Filler and alkali-activated based cements.

[0025] “clinker” is understood as the main constituent phase of Ordinary Portland Cement obtained from the co-calcination of limestone and an aluminosilicate source.

[0026] "mortar" and “concrete” refers to a material composed of binder(s), aggregates such as sand and other components, like admixtures.

[0027] "Dry industrial mortar composition or dry concrete composition" refers to a material composed of binders), aggregates such as sand and gravel and other components, like admixtures.

[0028] “Wet industrial mortar formulation or wet concrete formulation” refers to a material composed of binder(s), aggregates such as sand and gravel and other components, like admixtures and water.

[0029] “Hardened industrial mortar product or hardened concrete product” refers to the hardened product obtained from wet industrial mortar composition after reaction and evaporation of the water.

[0030] "d5o" gives the median size of the granulometric distribution of material’s particles (usually in micrometers for cementation materials). It means that 50% of the particles have a diameter size less than the dso number and 50% of the particles have a size greater than the dso number. The measurement of dso is done by Laser diffraction analysis, also known as Laser diffraction spectroscopy, by means of Laser diffraction analyzer such as "SYMPATEC" and commercialized by the SYMPATEC company, with the dry way method.Brief Description of DrawingsFig. 1 - Fig. 4

[0031] Figures 1 to 4 are XRD diagrams.Fig. 5 - Fig. 10

[0032] Figures 5 to 10 are bar diagrams of compressive strength.Fig. 11

[0033] [Fig. 11] is a schematic representation of a rheometer.Fig. 12 - Fig. 16

[0034] Figures 12 to 16 are diagrams of shear rate against stress.Detailed descriptionThe process for preparing a pozzolanic material

[0035] As mentioned above, the present disclosure relates to a process for preparing a pozzolanic material comprising the following steps:S1 : providing a raw material RM component comprising:- a phyllosilicate RM1 , and,- at least one mineral compound RM2 different from RM1 , and selected in the group comprising waste glass, granulated blast furnace slag (GBS), steel slag, such as basic oxygen furnace (BOF) or electric arc furnace (EAF), ladle slag, reducing electric furnace (REF) or ground granulated blast furnace slag (GGBS), and mixtures thereof,S2: grinding said raw material provided at step S1 leading to said pozzolanic material PM, wherein said grinding step S2 is performed by providing an energy collision and / or a density of collisions in a quantity more than the activation energy of RM, wherein the raw material RM is continuously at a temperature lower than or equal to 200°C, preferably lower than or equal to 150°C.

[0036] The process according to the present disclosure is particularly of interest for several reasons. Indeed, first the process does not require to heat at high temperatures the raw material. Second, it allows to activate several phyllosilicates at once. Third it is also possible to activate a raw material containing soils, i.e. it is not mandatory to purify the raw material to isolate the phyllosilicate(s) from the soil.Step S1

[0037] Step S1 consists of providing a raw material RM comprising RM1 and RM2. As mentioned above, one of the advantages of the process according to the present disclosure is the combined activation of several inert materials.

[0038] Thus, the process according to the present disclosure is performed on a mixture of raw materials that may be activated to confer a pozzolanic behavior to said raw material. Surprisingly, the inventors have successfully activated a mixture of a phyllosilicate with at least another phyllosilicate and / or at least one mineral compound that may be activated.

[0039] Said phyllosilicate RM1 may be selected in the group comprising, preferably consisting of, kaolinite, illite, montmorillonite, muscovite, sepiolite and chlorite. Indeed, the process according to the present disclosure is particularly efficient for phyllosilicate, such as natural clays.

[0040] As such, the raw material RM, may be a soil containing several phyllosilicates, or a soil containing one phyllosilicate and at least one mineral compound without any purification step.Step S2

[0041] Step S2 consists of grinding said raw material provided at step S1 leading to said pozzolanic material PM, wherein said grinding step S2 is performed by providing an energy collision and / or a density ofcollisions in a quantity more than the activation energy of RM, at a temperature under calcination temperature of RM.

[0042] The grinding may be implemented with a ball mill.

[0043] The balls may present a diameter comprised between 5 mm and 50 mm, preferably between 10 mm and 30 mm.

[0044] The ratio of balls to RM may be comprised between 1 and 60, preferably between 8 and 50, more preferably between 10 and 40.

[0045] The loading, corresponding to volume ratio between the solids and the grinding chamber volumes, may be comprised between 10% and 50%, more preferably between 20% and 40%.

[0046] The total quantity of energy collision and density of collision may be varied as long as the sum provides more energy than the activation energy of RM, without the need of heating. By «activation energy» is meant the energy, provided either, or combined, under physical form, chemical form or mechanical form, necessary to dehydroxylate a given, or a mixture of, phyllosilicate.

[0047] The step of phyllosilicate(s)’s dehydroxylation is mandatory so that the RM can exhibit a pozzolanic behavior. Activation energy calculation method is presented in references below:(1) Redfern, S. A. T. (1987). The kinetics of dehydroxylation of kaolinite. Clay Minerals, 22(4), 447- 456.(2) Gualtieri, A. F., & Ferrari, S. (2006). Kinetics of illite dehydroxylation. Physics and Chemistry of Minerals, 33, 490-501 .

[0048] Indeed, the present process is distinct from a calcination process since it does not require any external heat. In other words, even if it may be advantageous to heat lightly, i.e. at a temperature lower than or equal to 200°C, so as to dry the raw material, in the present process no heat source is needed. Due to energy collision or density of collisions, the temperature may be locally high. Nonetheless, the overall interior mill temperature, as measured by a probe positioned at the edge of milling balls container remains lower than or equal to 200°C.

[0049] In an advantageous embodiment, step S2 is performed with a co-grinding mineral said cogrinding mineral having a Mohs hardness greater than the Mohs hardness of said phyllosilicate and / or with a grinding aid, said grinding aid being preferably selected in the group comprising, preferably consisting of, alkanolamines, glycols, glycerol, sugars, sugar acids, carboxylic acids or their salts, superplasticizers, superabsorbent polymers, alkali salts, alkali-earth salts and mixtures thereof.The XRD diagram of the raw material compared to the XRD diagram of the pozzolanic material

[0050] Generally, inert phyllosilicates are crystalline and reactive phyllosilicate are amorphous. This is why natural clays have to be activated because they are, for a majority crystalline in the natural state.

[0051] However, to have a reactive phyllosilicate, it is not necessary mandatory that it is fully amorphous. It may contain some crystalline phases. Depending on the raw material, notably on the concentration of phyllosilicates, it may be unnecessary to fully amorphizing the phyllosilicates.

[0052] That is why in an embodiment of the present process, a comparison of an XRD diagram DRM of said RM with an XRD diagram DPM of said pozzolanic material shows that DPM has less peaks between 5° (2 Theta) and 24° (2 Theta) than the DRM and / or a ratio of mean full width half maximum of at least one peak of DPM to corresponding peak of DRM is equal or less than or equal to 0.7.

[0053] If the XRD diagram DPM shows less peaks, it means that at least one crystalline phyllosilicate phase has been totally removed, i.e. completely amorphized.

[0054] If the XRD diagram DPM shows a ratio of mean full width half maximum of at least one peak of DPM to corresponding peak of DRM is equal or less than or equal to 0.7, preferably less than or equal to 0.5, and more preferably less than or equal to 0.3, it means that the raw material has been sufficiently amorphized to possess a pozzolanic behavior.

[0055] In a preferred embodiment, the grinding is performed until DPM shows no peak between 5° (2 Theta) and 24° (2 Theta).The pozzolanic material

[0056] As previously mentioned, the disclosure also pertains to a pozzolanic material obtained by the process of the present disclosure.

[0057] According to the present disclosure, “Pozzolanic material” is understood as meaning a powdery substance either from natural origin or derived from a natural resource to which a treatment was applied. It refers more particularly to the type of materials that hardens by adding a mixture of water and a CaO source.

[0058] The pozzolanic material obtained by the present process is surprisingly more efficient than a pozzolanic materials obtained by calcination, as calcined clays.

[0059] Without being bound by a theory, the inventors thinks that applying step S2 induces two revealing properties of RM that cannot be observed when calcination is applied to the same RM: (1) an improved rheology, determined in terms of yield stress and viscosity, when the material is mixed water and (2) a modification of phyllosilicate(s) particle shape from a plate-like structure typically observed in RM and after calcination of RM into a spherical shape.

[0060] The pozzolanic materials according to the invention can also be characterized by a comparison wherein a suspension of RM in water at a solid ratio SR exhibits a yield stress and viscosity greater than a suspension of PM in the same water at a solid ratio SR.

[0061] The pozzolanic materials according to the invention can also be characterized by a comparison wherein a suspension of calcined RM in water at a solid ratio SR2 exhibits a yield stress and viscosity greater than a suspension of PM in the same water at a solid ratio SR2.

[0062] In this later case, the comparison is carried out by calcinating RM at a temperature between 400°C and 1000°C, depending on the raw material in an oven.The hydraulic binder

[0063] The disclosure is also directed to a hydraulic binder comprising the pozzolanic material of the present disclosure.

[0064] The binder composition may advantageously be enriched with one or several other components which are ingredients, notably functional additives preferably selected in the following list:• Water retention agent.

[0065] A water retention agent has the property to keep the water of mixing before the setting. The water is so trapped in the wet formulation paste which improves its bond. To some extent, the water is less absorbed by the support.

[0066] The water retentive agent is preferably chosen in the group comprising: modified celluloses, modified guars, modified cellulose ethers and / or guar ether and their mixes, more preferably consisting of: methylcelluloses, methylhydroxypropylcelluloses, methylhydroxyethyl-celluloses and their mixes.• Rheological agen t

[0067] The possible rheological agent (also named a "thickener") is preferably chosen in the group comprising, more preferably consisting in: starch ethers, cellulose ethers and / or gums (e.g. Welan guar xanthane, succinoglycans), modified polysaccharides -preferably among modified starch ethers-, polyvinylic alcohols, polyacrylamides, sepiolites, and their mixes.• Defoamer / Antifoams

[0068] The possible defoamer is preferably chosen in the group comprising, more preferably consisting in: polyether polyols and mixes thereof.• Biocide

[0069] The possible biocide is preferably chosen in the group comprising, more preferably consisting in: mineral oxides like zinc oxide and mixes thereof.• Pigment

[0070] The possible pigment is preferably chosen in the group comprising, more preferably consisting in: TiC>2, iron oxide and mixes thereof.• Flame retardant

[0071] Flame retardant (or flame proof agent) makes it possible to increase the fire resistance and / or to shrink the speed of flame spreading of the composition.• Air-entraining agents

[0072] Air-entraining agents (surfactants) are advantageously chosen in the group comprising, more preferably consisting in, natural resins, sulfated or sulfonated compounds, synthetic detergents, organic fatty acids and their mixes, preferably in the group comprising, more preferably consisting in the lignosulfonates, the basic soaps of fatty acids and their mixes, and, more preferably in the group comprising, more preferably consisting in the sulfonate olefins, the sodium lauryl sulfate and their mixes.• Retarders

[0073] Retarders are advantageously chosen in the group comprising, more preferably consisting in tartric acid and its salts: sodium or potassium salts, citric acid and its salts: sodium (trisodic citrate) and their mixes.

[0074] In addition, other components may be:• Plasticizers• Fibres• Dispersion powders• Wetting agents• Polymeric resins• Complexing agents• Drying shrinkage reducing agents based on polyols.

[0075] The total content of these optional other components in the binder composition is preferably comprised between 0,001 % and 10% by weight of the total weight of the binder composition.The dry concrete composition or dry industrial mortar composition

[0076] The disclosure is further directed to a dry industrial mortar composition or dry concrete composition, comprising at least one aggregate and the hydraulic binder mentioned above.

[0077] The dry concrete or industrial mortar composition may eventually contain other admixtures and additions.

[0078] According to the invention, “dry” concrete composition or “dry” industrial mortar composition refers to composition that are in the form of powder and ready to be mixed with water. In other words, the dry concrete composition or dry industrial mortar composition of the invention may content some moisture, but it essentially contains solid components which are intended to be mixed with water before its application.

[0079] Aggregates comprise a large category of particulate material used in construction, including sands, gravels, crushed stones, slag (not-granulated), recycled concrete and geosynthetic aggregates. They serve as reinforcement to add strength to the overall composite material.

[0080] Advantageously, said dry concrete composition or dry industrial mortar composition can also include, apart from aggregates, one or several ingredients, especially functional admixtures, additions and fibres, which can be the same as the other optional component mentioned above defined in the detailed description of the binder composition.

[0081] The total content of these optional other components in the dry concrete composition or dry industrial mortar composition is preferably comprised between 0.1 % and 10% by weight of the total weight of the binder composition.The wet concrete composition or wet industrial mortar composition

[0082] In addition, the disclosure relates to a wet industrial mortar formulation or wet concrete formulation comprising at least one aggregate, the hydraulic binder mentioned above and water.

[0083] More specifically, the disclosure relates to a wet building material formulation in particular, concrete, especially concrete for ready-mix and precast applications, bagged concrete and industrial mortars such as tile adhesive, coating, masonry industrial mortar, repair industrial mortar, render, bagged cement, technical industrial mortar, industrial mortars for floor covering or waterproofing membrane, comprising at least one aggregate, the hydraulic binder composition described above and water.The process for preparing wet concrete formulation or wet mortar formulation

[0084] The disclosure is additionally drawn to a process for preparing the wet industrial mortar formulation or wet concrete formulation mentioned above comprising a step of mixing with water, at least one aggregate, with other optional components, and the hydraulic binder mentioned above, the hydraulic binder being prepared before the mixing step or in situ during the mixing step from at least some of the different components of the hydraulic binder composition taken separately and / or under the form of premix(es).

[0085] In other words, wet concrete formulation or wet industrial mortar formulation could be prepared by two distinct methods.

[0086] In a first method, the hydraulic binder composition is prepared, and then mixed with the at least one aggregate, with other optional components. The dry concrete composition or dry mortar composition is thereafter mixed with water.

[0087] In a second method, the wet concrete formulation or wet industrial mortar formulation is prepared by mixing in water each component of the hydraulic binder composition and the aggregates.

[0088] According to the present disclosure, the term "mixing" has to be understood as any form of mixing.

[0089] In a preferred embodiment a part of the binder composition and at least a part of the water are mixed together prior to the mixing with the aggregate.

[0090] In a preferred embodiment, the process is implemented with a ratio water to hydraulic binder is comprised between 0.1 and 0.7, advantageously between 0.2 and 0.6, and more advantageously between 0.3 and 0.5.The hardened concrete composition or hardened industrial mortar composition

[0091] As mentioned above, the present disclosure is about a hardened industrial mortar product or hardened concrete product obtained from the wet industrial mortar formulation or wet concrete formulation mentioned above.ExamplesExample 1: Method of activation according to the invention

[0092] The raw material RM provided at step S1 is selected from the following:

[0093] Velay clay (VC) - it can be considered as a pure non-swelling clay sample consisting quartz in only trace amounts; this is mostly illitic clay (59%), layered alumino silicate with the 2:1 structure. Kaolinite and chlorite are present as well. This clay comes from Velay, France.

[0094] Lomme clay (LC) - a natural clay from a brick factory quarry (Lomme, France); the major clay’s constituent is smectite-type clay (59%); illite and kaolinite are present as well; here we find a mixture of clays and quartz;

[0095] Templeuve clay (TC) - a natural clay from a brick factory quarry (Templeuve, France); the major clay’s constituent is smectite-type clay (69%); illite and kaolinite are present as well; here we can observe a mixture of clays and quartz;

[0096] Templeuve silt (TS) - Silt is a granular material of a size between sand and clay and can be composed of broken grains of quartz and different mineral particles. Here we have quartz as the major constituent of the sample with a certain clay amount which is smectite type clay (89%).

[0097] The step S2 was performed on the clays samples that were firstly dried at 105°C for at least 24 hours until complete free water evaporation.

[0098] Then the material was introduced into the ball mill using the balls: powder ratio of 10. The high intensity grinding was applied for 3 different time intervals - 15 min, 30 min and 1 hour. No heat energy was provided to the mill, and functioned at room temperature.Example 2 Calcination process (counter example)

[0099] The optimum temperature for the mixed clays can be very difficult to define to avoid undercalcination or recrystallization of the minerals.

[0100] The raw material was dried at 105°C and then ground thoroughly with a mortar and pestle to obtain a powder. Then the samples were introduced into ‘Carbolite’ oven for 2 hours at a temperature of 800°C for Lomme clay (LC), Templeuve clay (TC) and Templeuve silt (TS) and at a temperature of 900°C for Velay clay (VC).

[0101] Low intensity ball mill grinding was performed for the calcined samples for 10 minutes to obtain particle size distribution similar to the samples obtained by the process according to the invention.Example 3: Transformation of clays and pozzolanicity measurements

[0102] Each sample listed in example 1 has been used as raw material RM in the process according to the invention, during different time periods, or calcined.

[0103] XRD test have been performed on RM material and processed samples.

[0104] Figure 1 shows the XRD diagram of Velay Clay. It can be seen that the peaks of the reference sample were considerably transformed after applying the process of the invention for 1 hour - the peak of illite decreased considerably suggesting amorphization; the peak of kaolinite disappeared. In contrast to the process of the invention, the thermal activation did not affect illite peak - only kaolinite was transformed.

[0105] Figure 2 shows the XRD diagram of Lomme clay. In the case of Lomme clay, the process of the invention of different time intervals was effective in amorphization of the reference sample, but especially 1 hour of grinding - all the clays peaks were impacted (illite, kaolinite, chlorite, montmorillonite). Once again, the calcination did not affect illite peaks - only kaolinite, chlorite and montmorillonite were dehydroxylated.

[0106] Figure 3 shows the XRD diagram of Templeuve clay. Templeuve clay shows the same response toward the process of the invention and calcination as Lomme clay - the process of the invention was very effective in transformation of all the clays’ peaks, but not calcination, especially for the illite clay.

[0107] Figure 4 shows the XRD diagram of Templeuve silt. The transformation of clays’ peaks occurred for all time intervals of the process of the invention for the Templeuve silt sample. Thermal activation was not enough to dehydroxylate illite.

[0108] In order to assess the reactivity of the obtain pozzolanic material following the process of the invention, the R3 test was applied. This test was performed according to ASTM C1897-20. The material can be considered as pozzolanic if it exceeds 100 J / g.

[0109] Table below presents 7-days’ cumulative heat results of the considered samples. Velay clay gives an example of the reference sample - its pozzolanic properties are poor. For all the samples process by the process of the invention, the values of cumulative heat produced at 7 days are much higher than for the samples that were activated thermically.Example 4: mechanical performance

[0110] Table below compares the particles size at d50 of the clays samples before and after mechano-chemical or thermal activation. Both procedures made particles finer.

[0111] The measurements were performed using Sympatec HELOS apparatus. A small amount of powder (1-2 g) was dispersed with compressed air before laser diffraction. The calculations are performed with parameter-free Fraunhofer evaluation.

[0112] The samples for the compressive strength measurements were mixed according to EN 196- 3 on the paste scale by changing the water to binder ratio to w:b=0.3. The compressive strength of the samples was performed according to EN 196-1 .

[0113] Only activated samples were tested because of the very problematic rheology of the binders with the reference samples of the clays.

[0114] The labelling of the samples is related to the name of a clay:

[0115] LC - Lomme clay

[0116] TC - Templeuve clay

[0117] TS - T empleuve silt

[0118] VC - Velay clay

[0119] and the type of the activation:

[0120] M - the process of the invention for 1 hour

[0121] MS - the process of the invention for 30 min with sand addition as a co-grinding agent (15% dry weight of clay)

[0122] T1 - thermally activated at 800°C

[0123] T2 - thermally activated at 900°C.

[0124] Other materials are the following:OPC (Ordinary Portland cement)

[0125] OPC described as CEM I 52.5R according to the standard EN 197-1Filler

[0126] The filler here is limestone fillerAnhydrite

[0127] Anhydrite used here is natural ground calcium sulfateNa2SO4 et triisopropanolamine (TIPA)

[0128] High purity chemical products were ordered (‘analytical grade’)

[0129] As can be seen, the samples with clays processed by the process of the invention perform much better than with the thermally activated. Figures 5 to 8 are bar diagrams of samples set forth in the table above.5 Example 5: Compressive strength - CEM ll / C-M (mortars scale)

[0130] A normalized cement CEM ll / C-M was selected to test the MCA technology on a larger type of binders according to the standard NF EN 197-5.

[0131] The samples for the compressive strength were mixed according to EN 196-3 with w:b=0.5. The compressive strength of the samples was performed according to EN 196-1 .10

[0132] The labelling of the samples is related to the name of a clay:

[0133] LC - Lomme clay

[0134] TC - Templeuve clay

[0135] and the type of the activation:

[0136] M - the process of the invention for 1 hour

[0137] T1 - thermally activated at 800°C

[0138] The results show that CEM ll / C-M mortars with MCA clays develop higher early and longterm strength compared to the mortars with calcined clays. Figures 9 and 10 are bar diagrams of samples set forth above.Example 6: Rheology measurements

[0139] Regarding the complex nature of clays, rheology is an important parameter, and it plays a crucial role in creating low-carbon binders with low water binder ratio.

[0140] Here the rheological behavior of clays before and after activation dispersed in water is evaluated.

[0141] To demonstrate how the rheological properties were impacted by two different methods of clays treatment - calcination and the process of the invention - the samples were subjects to the rheological test using a stress-controlled rheometer AR2000ex from TA Instruments (see figure 11). The geometry that was selected is two parallel cross-hatched disks - the material is thus confined between the two shearing plates. The distance between two disks was fixed to 1 mm.

[0142] The experiments were carried out with a constant temperature maintained by a Peltier system at 20°C. A preshearing stage of 30 s at 30 1 / s was performed before flow experiments - the ramp 0.1-100 1 / s with 5 points per decade. Here the evolution of rheology was measured at different time intervals - 0 min, 10 min, 20 min.

[0143] The samples were prepared as follows:

[0144] The clay / water suspension was prepared by mixing clay in water until homogenization;

[0145] the optimum amount of water was selected individually by preparing a paste without segregation;

[0146] Two main parameters were measured: yield stress - is determined by the minimum value of the stress for low shear rate; viscosity - corresponds to the flow derivative of a flow curve - in our case the value is registered at the shear rate 100 1 / s.Velay clay

[0147] Both treatments - the process of the invention and calcination - lowered the yield stress of Velay clay, especially after 10 minutes of the test. Regarding the viscosity, it decreases considerably for the process of the invention sample but not for the calcined one.

[0148] Figure 12 shows a diagram of shear rate against stress.Lomme clay

[0149] A remarkable decrease in yield stress was produced for Lomme clay that has undergone the process of the invention or calcination treatment - the effect is more pronounced for the process of the invention. Moreover, the process of the invention sample showed the lowest viscosity.

[0150] Figures 13 and 14 (zoom) show a diagram of shear rate against stress.Templeuve clay

[0151] In the case of Templeuve clay, the process ofthe invention treatment produces lower viscosity and yield stress compared to the calcination procedure. Once again, the difference is remarkable compared to the reference sample.

[0152] Figures 15 and 16 (zoom) show a diagram of shear rate against stress.Example 7 mechanical performance of hydraulic binders

[0153] Raw material RM is provided as reflected in the table below.

[0154] The step S2 was performed on the RM samples that were firstly dried at 105°C for at least 24 hours until complete free water evaporation.

[0155] Then the material was introduced into the ball mill using the balls: powder ratio of 10. The high intensity grinding was applied for 1 hour. No heat energy was provided to the mill, and functioned at room temperature.

[0156] The samples for the compressive strength measurements were mixed according to EN 196- 3 on the paste scale by changing the water to binder ratio to w:b=0.3. The compressive strength of the samples was performed according to EN 196-1 .

[0157]

[0158] As can be seen, the samples with RM according to the invention (RM1 + RM2) processed by the process of the invention, i.e. sample E1 to E4 perform much better than the sample CE1 which does not include RM2.

Claims

Claims

1. Process for preparing a pozzolanic material comprising the following steps:S1 : providing a raw material RM component comprising: . a phyllosilicate RM1 , and, . at least one mineral compound RM2 different from RM1 , and selected in the group comprising waste glass, granulated blast furnace slag (GBS), steel slag, such as basic oxygen furnace (BOF) or electric arc furnace (EAF), ladle slag, reducing electric furnace (REF) or ground granulated blast furnace slag (GGBS), and mixtures thereof,S2: grinding said raw material provided at step S1 leading to said pozzolanic material PM, wherein said grinding step S2 is performed by providing an energy collision and / or a density of collisions in a quantity more than the activation energy of RM, wherein the raw material RM is continuously at a temperature lower than or equal to 200°C, preferably lower than or equal to 150°C.

2. Process according to claim 1 , wherein said phyllosilicate RM1 is selected in the group comprising, preferably consisting of, kaolin, illite, montmorillonite, muscovite, sepiolite and chlorite.

3. Process according to anyone of claims 1 or 2, wherein step S2 is performed with a grinding aid, said grinding aid being preferably selected in the group comprising, preferably consisting of, alkanolamines, glycols, glycerol, sugars, sugar acids, carboxylic acids or their salts, superplasticizers, superabsorbent polymers, alkali salts, alkali-earth salts and mixtures thereof.

4. Process according to anyone of claims 1 to 3, wherein step S2 of grinding is implemented with a ball mill.

5. Process according to claim 4, wherein balls present a diameter comprised between 5 mm and 50 mm, preferably between 10 mm and 30 mm.

6. Process according to anyone of claims 4 and 5, wherein a ratio of balls to RM is comprised between 1 and 60, preferably between 8 and 50, more preferably between 10 and 40.

7. Process according to anyone of claims 4 to 6, wherein the loading, corresponding to volume ratio between the solids and the grinding chamber volumes, may be comprised between 10% and 50%, more preferably between 20% and 40%.

8. Process according to anyone of claims 1 to 7, wherein a comparison of an XRD diagram DRM of said RM with an XRD diagram DPM of said pozzolanic material shows that DPM has less peaks between 5° (2 Theta) and 24° (2 Theta)than the DRM and / or a ratio of mean full width half maximum of at least one peak of DPM to corresponding peak of DRM is equal or less than or equal to 0.7.

9. Process according to any one of claims 1 to 8, wherein the grinding is performed until DPM shows no peak between 5° (2 Theta) and 24° (2 Theta).

10. Pozzolanic material obtained by the process according to anyone of claims 1 to 9.

11. Pozzolanic materials according to claim 10, wherein a suspension of RM in water at a solid ratio SR exhibits a yield stress and viscosity greater than a suspension of PM in the same water at a solid ratio SR.

12. Pozzolanic materials according to claim 10, wherein a suspension of calcined RM in water at a solid ratio SR2 exhibits a yield stress and viscosity greater than a suspension of PM in the same water at a solid ratio SR2.

13. Hydraulic binder comprising the pozzolanic material according to any one of claims 10 to 12.

14. Dry industrial mortar composition or dry concrete composition, comprising at least one aggregate and the hydraulic binder composition according to claim 13.

15. Wet industrial mortar formulation or wet concrete formulation comprising at least one aggregate, the hydraulic binder composition according to claim 13 and water.

16. Hardened industrial mortar product or hardened concrete product obtained from the wet industrial mortar formulation according to claim 15.

17. Process for preparing the wet industrial mortar formulation or wet concrete formulation according to claim 15 comprising a step of mixing with water, at least one aggregate and the hydraulic binder composition according to claim 13, the hydraulic binder composition being prepared before the mixing step or in situ during the mixing step from at least some of the different components of the hydraulic binder composition taken separately and / or under the form of premix(es).

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