ETTRINGITE BINDER FOR THE PRODUCTION OF BUILDING MATERIALS AND METHOD FOR ITS PRODUCTION

Description

FIELD OF THE INVENTION

[0001] The present invention relates to the field of building materials. In particular, the present invention relates to a method for preparing an ettringitic binder from a source of aluminosilicate, a source of calcium sulfate and a source of calcium hydroxide (or slaked lime, CH); said binder comprising a catalyst and an activator.

[0002] The present invention also relates to the use of the ettringitic binder obtained by the process of the invention to provide cements, masonry cements, mortars, concretes, road binders and / or formulated limes. STATE OF THE ART

[0003] The preparation of construction materials such as concrete or cement requires increasingly innovative binders to meet the growing needs in this area.

[0004] Among the known and used binders, ettringitic binders have the advantage when mixed with water, of hardening quickly to provide materials with low shrinkage and good chemical resistance.

[0005] These binders are mainly prepared using two methods: either by hydration of a Ye'elemite-based clinker (WO88 / 04285), or by formulation from an aluminous cement (WO03 / 091179).

[0006] US2014 / 360721 A aims to provide a low-cost cement having hardening and mechanical properties suitable for use in reinforcing subterranean formations such as gas or oil wellbores. It describes a cement composition that may include a source of aluminosilicate, a source of calcium sulfate, a source of calcium hydroxide, and an activator such as a hydrocarboxylic acid.

[0007] The first method, by hydration, requires manufacturing clinker at high temperatures (1200-1300°C). The second method, by formulation, requires the use of numerous additives and expensive raw materials.

[0008] There is therefore a need to provide a process for preparing an ettringitic binder that is simpler to implement and less energy-intensive. In particular, there is a need to provide a process for preparing an ettringitic binder without heating. Furthermore, there is a need to provide a more economical process that can be carried out using readily available and inexpensive raw materials and that has a lower carbon footprint than the processes of the prior art. To this end, the Applicant seeks in particular to provide an ettringitic binder process that can be obtained without the use of Portland cement. Indeed, its manufacture, in addition to requiring numerous resources, produces a significant quantity of pollutants, making its use undesirable for preparing a binder with a reduced carbon footprint.

[0009] Surprisingly, the Applicant has demonstrated that a mixture comprising at least one source of aluminosilicate, one source of calcium sulfate and lime, characterized by a stoichiometric ratio of calcium sulfate (RMK) available in the mixture in a range from 0.05 to 1.25; and a saturation rate of calcium hydroxide, Sat(CH), in a range from 0.75 to 8, allows the preparation of a stable ettringitic binder.

[0010] Furthermore, the Applicant has demonstrated that a mixture comprising at least one source of aluminosilicate, one source of calcium sulfate and one source of calcium hydroxide, in the presence of an activator chosen from compounds complexing cations such as calcium, aluminum and / or silicon, makes it possible to obtain materials having higher compressive strengths and with better yields than with conventional ettringitic binders.

[0011] Advantageously, the method of the invention makes it possible to provide a stable ettringitic binder. Thus, when using the ettringitic binder of the invention in the manufacture of a construction material, this does not lead over time to any swelling in the final material, while presenting better mechanical performances than conventional pozzolanic binders. SUMMARY

[0012] The present invention therefore relates to an ettringitic binder comprising: at least one source of aluminosilicate characterized by a pozzolanic activity index (PIZ) determined by the Chapelle test method, in a range of 200 to 2200 mg / g; at least one source of calcium sulfate; at least one source of calcium hydroxide; at least one alkaline catalyst chosen from sodium fluoride, sodium aluminate, trisodium phosphate, sodium orthosilicate, sodium metasilicate, sodium hexafluorosilicate, sodium fluorophosphate, sodium hexametaphosphate, sodium carbonate, sodium borate, sodium hexafluoroaluminate, potassium tetrafluoroaluminate or mixtures thereof; and at least one activator chosen from compounds capable of complexing cations, preferably compounds capable of complexing calcium, aluminum and / or silicon said ettringitic binder being characterized by a calcium hydroxide saturation rate, noted Sat(CH), in a range from 0.75 to 8; and a calcium sulfate rate, noted RMK, in a range from 0.05 to 1.25; the RMK parameter being defined by the following equation in which: IPZ represents the pozzolanic index of the aluminosilicate source; Q(MK) represents the quantity in grams of aluminosilicates present in the ettringitic binder; and

[0013] According to one embodiment, the activator is selected from sucrose, alpha-hydroxy acids or their salts, ethanolaniines or their salts, and / or catechols or its derivatives. According to one embodiment, the binder further comprises an alkaline catalyst, preferably the alkaline catalyst is selected from sodium fluoride, sodium aluminate, trisodium phosphate, sodium orthosilicate, sodium metasilicate, sodium hexafluorosilicate, sodium fluorophosphate, sodium hexametaphosphate, sodium carbonate, sodium borate, sodium hexafluoroaluminate, potassium tetrafluoroaluminate or mixtures thereof.

[0014] According to one embodiment, the amount of catalyst is in a range of more than 0% to 20% by mass relative to the total amount of binder.

[0015] According to one embodiment, the source of aluminosilicate is a pozzolan, a fine from the production of chamotte or ash from paper mill sludge, preferably a metakaolin.

[0016] According to one embodiment, the source of calcium hydroxide is slaked lime, hydraulic lime, quicklime, delayed quicklime, air lime, conventional slaked lime or any commercial lime.

[0017] According to one embodiment, the source of calcium sulfate is chosen from anhydrite, natural gypsum or gypsum obtained as a by-product of industrial reactions such as desulfogypsum, titanogypsum, fluogypsum, or phosphogypsum.

[0018] According to one embodiment, the binder further comprises additives, preferably slags, more preferably blast furnace slags or amorphous aluminate slags.

[0019] The aluminosiiicate source is characterized by a pozzolanic activity index (PIZ) determined by the Chapelle test method, within a range of 200 to 2200 mg / g.

[0020] According to one embodiment, the mixture (source of aluminosilicate / source of calcium sulfate / source of calcium hydroxide) comprises or consists of: 50% by mass of ARGICEM ® flashed metakaolin < of IPZ approximately equal to 800 mg / g; 25% by mass of lime; and 25% by mass of gypsum, relative to the total mass of the mixture.

[0021] According to one embodiment, the mixture (aluminosilicate source, calcium sulfate source / calcium hydroxide source) comprises or consists of: 60% by mass of ARGICEM ® flashed metakaolin < of IPZ approximately equal to 800 mg / g; 30% by mass of lime; and 10% by mass of gypsum, relative to the total mass of the mixture.

[0022] The present invention also relates to a process for preparing a binder as described above, comprising mixing at least: an aluminosilicate source characterized by a pozzolanic activity index (PIZ) determined by the Chapelle test method, in a range of 200 to 2200 mg / g; a calcium sulfate source; a calcium hydroxide source; at least one alkaline catalyst chosen from sodium fluoride, sodium aluminate, trisodium phosphate, sodium orthosilicate, sodium metasilicate, sodium hexafluorosilicate, sodium fluorophosphate, sodium hexametaphosphate, sodium carbonate, sodium borate, sodium hexafluoroaluminate, potassium tetrafluoroaluminate or mixtures thereof; and at least one activator chosen from compounds capable of complexing cations, preferably compounds capable of complexing calcium, aluminum and / or silicon; said ettringitic binder being characterized by a calcium hydroxide saturation rate, noted Sat(CH), within a range of 0.75 to 8;and a calcium sulfate rate, noted RMK, in a range from 0.05 to 1.25; the RMK parameter being defined by the following equation; in which: IPZ represents the pozzolanic index of the aluminosilicate source; Q(MK) represents the quantity in grams of aluminosilicates present in the ettringitic binder; and Qm(C$) represents the quantity in moles of calcium sulfate present in the ettringitic binder.

[0023] According to one embodiment, the temperature at which the mixing is carried out is from more than 0°C to 50°C, preferably from 10°C to 40°C, more preferably around 25°C.

[0024] The present invention also relates to the use of the ettringitic binder of the invention as described above, for the preparation of cements, masonry cements, mortars, concretes, road binders and / or formulated lime. DEFINITIONS

[0025] In the present invention, the terms below are defined as follows: " Alpha-hydroxy acid » relates to a carboxylic acid comprising a hydroxyl group (-OH) on the carbon adjacent to the carboxylic function. Activator » relates to any product capable of increasing the yield of the reaction during the formation of ettringite. Aluminosilicate » concerns a mineral chemical compound of the silicate family in which certain silicon (Si) atoms have been replaced by aluminum atoms. Anhydrite » relates to a mineral chemical compound of anhydrous calcium sulfate, with the empirical formula CaSO 4 . « Concrete » concerns a mortar in which the size of the aggregates is greater than 4 mm. Catalyst» relates to any product participating in a chemical reaction to increase its speed, but which is regenerated or eliminated during or at the end of the reaction. According to one embodiment, the term “catalyst” means any chemical product capable of accelerating the reaction speed between the source of aluminosilicate (such as a metakaolin for example) and the source of calcium hydroxide (such as slaked lime for example); preferably to obtain calcium aluminate. Alkaline catalyst » : relates to a catalyst comprising at least one alkaline element (i.e. at least one metal from the alkali metal group, preferably lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs) or francium (Fr)). « Catechol " Or " Pyrocatechol " Or " Benzene-1,2-diol » : relates to an organic compound of the empirical formula C 6 H 4 (OH) 2 . « Mud ash » : concerns the ashes resulting from the combustion of sludge obtained during the manufacture of paper pulp. Lime" Or " Air lime " Or " Slaked lime » : relates to a mineral chemical compound of calcium hydroxide, of the empirical formula Ca(OH) 2 . These terms designate lime obtained by hydration of quicklime. According to one embodiment, these terms also designate compounds having calcium hydroxide as their main component, and comprising solid impurities as minority compounds. Natural hydratilic lime » : concerns a lime which sets first in water then in air, formed from a limestone deposit containing a little clay. Quicklime » : refers to the anhydrous lime obtained from the lime kiln after pyrolysis at 900°C. Quicklime has calcium oxide (CaO) as its main component. Delayed effect lime » : concerns quicklime obtained from a special cooking process which slows down rehydration upon contact with water. Cement» : concerns a hydraulic binder (i.e. a mineral powder) which, when in contact with water or a saline solution, sets and hardens. Masonry cement » : concerns a cement whose performance has been modified in order to make it directly usable in masonry. Complexing » : relates to any product capable of complexing an ion; preferably a cation _; more preferably a cation of an alkaline earth metal. According to one embodiment, the complexing agent is a compound capable of complexing the element calcium (Ca), aluminum (Al), and silicon (Si). « Desulfogypsum » : designates a gypsum obtained during the desulfurization of coal and fuel combustion gases, in particular in the case of thermal power plants or nuclear power plants. According to one embodiment, the desulfurization gypsum is a manufacturing by-product (waste from thermal power plants). Ettringite» : designates a mineral species composed of hydrated calcium and aluminum sulfate, of formula Ca 6 Al 2 (SO 4 ) 3 (OH) 12 26H 2 O. « Ethanolamines » : relates to an organic compound of formula HO-(CH 2 ) 2 -NH 2 (monoethanolamine), of formula HO-(CH 2 ) 2 -NH-(CH 2 ) 2 -OH (diethanolamine), or of formula N[(CH 2 ) 2 -OH] 2 (triethanolamine). « Fluogypsum » : designates a gypsum obtained during the manufacture of hydrofluoric acid. According to one embodiment, the fluogyspe is a by-product of the manufacture of hydrofluoric acid (waste). Gypsum » : relates to a compound of calcium sulfate dihydrate, of formula CaSO 4. 2H 2 O. « IPZ " Or " Pozzolanic index " Or " Pozzonalic activity index»: represents the active fraction of an aluminosilicate such as a metakaolin, that is to say the quantity of calcium hydroxide, Ca(OH) 2 , which can be fixed in one gram of aluminosilicate. This index (expressed in mg / g) can be determined by methods known to those skilled in the art such as for example the Chapelle test (M. CYR and G. ESCADEILLAS, http: / / dspace.univtlemcen.dz / bitstream / 112 / 624 / 1 / Normalisation-du-metakaolin-pourquoicomment.pdf). « Milkman » : refers to the slag formed during the melting or production of a metal by liquid means. The slag is composed of a mixture of silicates, aluminates, and lime and optionally metal oxides with the exception of iron oxides. Blast furnace slag » : concerns any by-product of the steel industry formed during the preparation of cast iron from iron ore. Amorphous aluminate slag» : concerns a steel slag with a high aluminum content whose cooling process has made the structure amorphous. Hydraulic binder » : concerns any powdery mixture having the property during its hydration of solidifying then hardening by acquiring mechanical characteristics such as resistance to compression, resistance to traction, or adhesion. Ettriiigitic binder » : concerns a hydraulic binder whose constituents, when hydrated, transform and provide, as the main hydrate, ettringite of formula 3CaO.Al 2 O .3CaSO 4. 32H 2 O. « Metakaolin» : relates to a powder resulting from the calcination and grinding of a clay. According to one embodiment, the metakaloin is a powder resulting from the calcination and grinding of a clay composed mainly of kaolinite. According to one embodiment, the metakaolin is a powder consisting mainly of amorphous alumina silicate particles composed essentially of reactive silicon oxide (SiO 2 ) and aluminum oxide (Al 2 O 3 ). Mortar » : relates to a formulation comprising or consisting of a binder, sand, water, and optionally additives. Phosphogypsum » : designates the gypsum formed during the manufacture of phosphoric acid from natural phosphate. According to one embodiment, the phosphogypsum is a by-product of the manufacture of phosphoric acid (waste). Pozzolan » : concerns a silico-aluminous material, natural or artificial, capable at ordinary temperature and in the presence of water, of combining with lime. RMK» is defined by the following equation: in which: IPZ represents the pozzolanic index of the aluminosilicate source; Q(MK) represents the mass quantity, preferably in grams, of aluminosilicates present in the ettringitic binder; and Qm(C$) represents the molar quantity of calcium sulfate present in the ettringitic binder. Sucrose » : designates a chemical compound of a glucose molecule and a fructose molecule united by their reducing groups and of formula C 12 H 22 O 11 . « Sat(CH) » represents the mass saturation rate of calcium hydroxide, Ca(OH) 2 in a given composition. It is determined according to the following equation (e1): where: Q(CH) represents the quantity in grams of calcium hydroxide (Ca(OH) 2 ) in the mixture of the invention; and QST(CH) represents the quantity in grams of calcium hydroxide stoichiometrically necessary for the ettringite formation reaction. The parameter QST(CH) can be determined according to the following equation (e2): where: IPZ represents the pozzolanic index as defined previously; Q(MK) represents the quantity in grams of metakaolin or aluminosilicates present in the mixture; and P(CH) represents the purity of the source of calcium hydroxide such as for example lime, in calcium hydroxide. Calcium sulfate » : concerns an anhydrous mineral chemical compound, of formula CaSO 4 . « Titanogypsum » : refers to the gypsum formed during the manufacture of titanium. According to one embodiment, titanogypsum is a by-product during the manufacture of titanium (waste). Demolition plaster» : refers to gypsum obtained by grinding plasterboard or any form of construction gypsum. DETAILED DESCRIPTION Process

[0026] The invention therefore relates to a process for preparing an ettringitic binder. According to one embodiment, the process of the invention relates to the preparation of a hydraulic binder for the formation of ettringite as the main hydrate, preferably primary ettringite.

[0027] In particular, the invention relates to a process for preparing an ettringitic binder comprising a step of mixing at least: a source of aluminosilicate; characterized by a pozzolanic activity index (PIZ) determined by the Chapelle test method, in a range of 200 to 2200 mg / g; a source of calcium sulfate; and a source of calcium hydroxide (or lime); at least one alkaline catalyst chosen from sodium fluoride, sodium aluminate, trisodium phosphate, sodium orthosilicate, sodium metasilicate, sodium hexafluorosilicate, sodium fluorophosphate, sodium hexametaphosphate, sodium carbonate, sodium borate, sodium hexafluoroaluminate, potassium tetrafluoroaluminate or mixtures thereof; and at least one activator chosen from compounds capable of complexing cations, preferably compounds capable of complexing calcium, aluminum and / or silicon, said mixture having: a saturation level of calcium hydroxide, noted Sat(CH), in a range from 0.75 to 8; and a calcium sulfate level, noted RMK, in a range from 0.05 to 1.25; the parameters RMK and Sat(CH) being defined according to claim 1.

[0028] In one embodiment, the aluminosilicate source comprises or consists of an aluminosilicate. In one embodiment, the aluminosilicate source comprises or consists of a metakaolin, a calcined clay, or a fine from the production of chamotte. In one embodiment, the method for preparing an ettringitic binder does not include the use of Portland cement. In one embodiment, the aluminosilicate source is a pozzolan, a fine from the production of chamotte, or paper mill sludge ash, preferably a metakaolin.

[0029] According to one embodiment, the metakaolin is a commercial product, preferably the metakaolin is Argicem ®< metakaolin, Argical M1000 ®< metakaolin, Argical M1200S ®< metakaolin, Metastar ®< M501, Soka Metasial ®< or their equivalents. According to one embodiment, the aluminosilicate source is a fine from the chamotte industry. According to one embodiment, the calcium sulfate is selected from anhydrite, natural gypsum or gypsum obtained as a by-product of industrial reactions such as desulfogypsum, titanogypsum, fluogypsum, or phosphogypsum. According to one embodiment, the calcium sulfate source comprises or consists of gypsum, anhydrite and / or gypsum. According to one embodiment, the calcium sulfate source is alpha and / or beta gypsum. According to one embodiment, the source of calcium sulfate comprises or consists of anhydrite, preferably natural anhydrite.

[0030] In one embodiment, the source of calcium hydroxide is slaked lime. In one embodiment, the source of calcium hydroxide is air lime. In one embodiment, the source of calcium hydroxide is hydraulic lime. In one embodiment, the source of calcium hydroxide is air lime. In one embodiment, the source of calcium hydroxide is obtained from quicklime.

[0031] According to one embodiment, the source of calcium hydroxide is chosen from commercial limes such as, for example, LHOIST ® lime < CL80, LHOIST ® lime < CL90, LHOIST Sorbacal ® lime or Decorchaux ® slaked air lime < CL90.

[0032] According to one embodiment, the binder of the invention may further comprise at least one secondary additive such as a filler, preferably a limestone filler.

[0033] According to one embodiment, the secondary additive is a mineral filler, preferably chosen from limestone fillers, siliceous fillers or granulated slags.

[0034] The invention relates to a method for preparing an ettringitic binder comprising a step of mixing at least: a source of aluminosilicate; a source of calcium sulfate; a source of calcium hydroxide (or lime); and a setting accelerator mixture comprising a catalyst and an activator.

[0035] The addition of at least one catalyst and at least one activator to the binder makes it possible to accelerate the setting of the binder during its hydration to obtain a construction material.

[0036] According to one embodiment, the invention relates to a method for preparing an ettringitic binder comprising a step of mixing at least: a source of aluminosilicate; a source of calcium sulfate; a source of calcium hydroxide (or lime); sucrose; tartaric acid; and an alkali aluminate, preferably sodium aluminate.

[0037] According to one embodiment, the binder of the invention does not comprise oxalic acid, triethanolamine and / or potassium aluminate. According to one embodiment, the binder of the invention does not comprise tartaric acid and / or sucrose. According to one embodiment, the binder of the invention does not comprise mucic acid, malic acid, tartaric acid, citric acid, sucrose and / or hydroxypolycarboxylic acid.

[0038] According to one embodiment, the mixture comprises: an ARGICEM ® flashed metakaolin with an IPZ of between 700 and 800 mg / g; a CL90 type slaked lime with a LEDUC lime content of approximately 90%; and gypsum.

[0039] According to one embodiment, the binder of the invention comprises: an Argical M1000 ® metakaolin; a quarry calcium sulfate; CL90 lime; a catalyst; and an activator.

[0040] According to one embodiment, the binder comprises from more than 0% to 20%, preferably from more than 0% to 15%, more preferably from 1% to 10%, by mass of catalysts relative to the total mass of the binder. According to one embodiment, the binder comprises from 1% to 20%, preferably from 2% to 20%, from 3% to 20%, from 4% to 20%, from 5% to 20%, from 6% to 20%, from 7% to 20%, from 8% to 20%, from 9% to 20%, from 10% to 20%, from 11% to 20%, from 12% to 20%, from 13% to 20%, from 14% to 20%, from 15% to 20%, from 16% to 20%, from 17% to 20%, from 18% to 20%), from 19% to 20%, by mass of catalysts relative to the total mass of the binder. According to one embodiment, the binder comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20% by mass of catalysts relative to the total mass of the binder.

[0041] According to one embodiment, the binder comprises from 1% to 10% of activators by mass relative to the total mass of the binder. According to one embodiment, the binder comprises from 1% to 20%, preferably from 2% to 20%, from 3% to 20%, from 4% to 20%, from 5% to 20%, from 6% to 20%, from 7% to 20%, from 8% to 20%, from 9% to 20%, from 10% to 20%, from 11% to 20%, from 12% to 20%, from 13% to 20%, from 14% to 20%, from 15% to 20%, from 16% to 20%, from 17% to 20%, from 18% to 20%, from 19% to 20%, of activators by mass relative to the total mass of the binder. According to one embodiment, the binder comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20% of activators by mass relative to the total mass of the binder.

[0042] According to one embodiment, the binder comprises from more than 0% to 2%, preferably from more than 0%; 0.1; 0.2; 0.3; 0.4; 0.5; 0.6; 0.7; 0.8; 0.9; 1; 1.1; 1.2; 1.3; 1.4; 1.5; 1.6; 1.7; 1.8; 1.9 or 2%, of activators and / or catalysts by mass relative to the total mass of the binder.

[0043] According to one embodiment, the mixture comprises from 1% to 30%, preferably from 5% to 20%, of secondary additives by mass relative to the total mass of the mixture or binder. According to one embodiment, the mixture comprises from 1% to 30%, preferably from 2% to 30%, 3% to 30%, 4% to 30%, 5% to 30%, 6% to 30%, 7% to 30%, 8% to 30%, 9% to 30%, 10% to 30%, 12% to 30%, 13% to 30%, 14% to 30%, 15% to 30%, 16% to 30%, 17% to 30%, 18% to 30%, 19% to 30%, 20% to 30%, 21% to 30%, 22% to 30%, 23% to 30%, 24% to 30%, 25% to 30%, 26% to 30%, 27% to 30%, 28% to 30%, or 29% to 30% of secondary additives by mass relative to the total mass of the mixture or binder. According to one embodiment, the mixture comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30% of additives by mass relative to the total mass of the mixture or binder.

[0044] According to one embodiment, the addition of secondary additive allows an increase of 1% to 100%, preferably of 5% to 60% in the mechanical performance, in particular the compressive strength, of the material obtained from the ettringitic binder of the invention, compared to the same mixture of the invention without secondary additive.

[0045] Advantageously, the addition of secondary additive in the mixture of the invention leads to a synergy of the mechanical performances of the material obtained from the ettringitic binder of the invention. Advantageously, the addition of secondary additive in the mixture of the invention makes it possible to reduce the water demand and to modify the dimensional shrinkage when using the ettringitic binder of the invention.

[0046] According to one embodiment, the mixture of the invention further comprises an adjuvant, preferably chosen from water reducers and / or superplasticizers, water-repellent agents, anti-foaming agents, air entrainers, and / or fibers.

[0047] According to one embodiment, the water reducer and / or the superplasticizer is a polymer; preferably chosen from poly(meth)acrylics, polycarboxylates, and / or polyolefins such as polyethylenes (PE), or their copolymers; more preferably the water reducer is chosen from the products marketed by the company SIKA: Tempo 9 ®< , Tempo 12 ®< , Viscocrete 125 ®< , Viscocrete 150 ®< , Viscocrete 225 ®< , Viscocrete 430 ®< , Viscocrete 111 ®< , Viscocrete 510 ®< or Viscocrete 250 ®< .

[0048] According to one embodiment, the water reducer is not a lignosulfonate.

[0049] According to one embodiment, the water-repellent agent is chosen from silicones and / or carboxylic acid salts; preferably silicones and / or stearates. According to one embodiment, the water-repellent agent is chosen from the commercial products SiKA Hydrofuge HW ®< , SIKA WT-115 ®< , Dow Corning SHP 50 ®< , Dow Corning SHP 60+ ®< , and Dow Corning IE 6692 ®< . According to one embodiment, the water-repellent agent is chosen from magnesium stearate, calcium stearate and aluminum stearate.

[0050] According to one embodiment, the anti-foaming agent is a siloxane, preferably a poly(siloxane), more preferably polydimethylsiloxane (PDMS).

[0051] According to one embodiment, the air entrainer is chosen from the commercial products SIKA AER ®< , preferably SIKA AER 5 ®< and SIKA AER 200 ®< . In the present invention, the term "air entrainer" means any chemical compound or formulation making it possible to provide fine air bubbles in a mixture. According to one embodiment, the air entrainer provides air bubbles with an average diameter of 10 to 500 µm. According to one embodiment, the fibers are chosen from metal fibers, polymer fibers such as polyethylene fibers, plant fibers and / or glass fibers.

[0052] According to one embodiment, the curing agents are chosen from the commercial products Pieri Cure & Fix ®< , and Antisol ®< . In the present invention, the term "curing product" means any compound capable of limiting the evaporation of water during the hardening of concrete or mortar from the ettringitic binder of the invention.

[0053] According to one embodiment, the formwork oil is chosen from natural or synthetic, vegetable or mineral oils; preferably vegetable oils; more preferably Decoffre Emulsion Végétale E ®< oil marketed by the company SIKA or Decoffrage Végétale ®< oil marketed by the company Deltapro.

[0054] According to one embodiment, the ettringitic binder is anhydrous. According to one embodiment, the ettringitic binder does not comprise a sufficient amount of water to hydrate the compounds of the mixture and / or to cause the ettringitic binder to harden. According to one embodiment, the ettringitic binder further comprises water.

[0055] The ettringitic binder or mixture is characterized by: a calcium hydroxide saturation rate, noted Sat(CH), in a range from 0.75 to 8; and a calcium sulfate rate, noted RMK, in a range from 0.05 to 1.25; the RMK parameter being defined by the following equation: in which: IPZ represents the pozzolanic index of the aluminosilicate source; Q(MK) represents the quantity in grams of aluminosilicates present in the ettringitic binder; and Qm(C$) represents the quantity in moles of calcium sulfate present in the ettringitic binder.

[0056] The pozzolanic index IPZ is in a range of 200 to 2200 mg / g, preferably 400 to 2000 mg / g, more preferably 600 to 1800 mg / g. According to one embodiment, the pozzolanic index IPZ is preferably in a range of 550 to 2200 mg / g, 600 to 2200 mg / g, 700 to 2200 mg / g, 800 to 2200 mg / g, 900 to 2200 mg / g, 1000 to 2200 mg / g, 1100 to 2200 mg / g, 1200 to 2200 mg / g, 1300 to 2200 mg / g, 1400 to 2200 mg / g, 1500 to 2200 mg / g, 200 to 1900 mg / g, 200 to 1800 mg / g, 200 to 1700 mg / g, 200 at 1600 mg / g, from 200 to 1500 mg / g, from 200 to 1400 mg / g, from 200 to 1300 mg / g, from 200 to 1200 mg / g, from 200 to 1100 mg / g, from 200 to 1000 mg / g, from 200 to 900 mg / g. According to one embodiment, the pozzolanic index IPZ is comprised of 600, 700, 800, 900, 1000, 1100, 1200, 1300 or 1400 mg / g.

[0057] The RMK parameter as defined above is comprised in a range from 0.05 to 1.25; preferably from 0.1 to 1; more preferably from 0.2 to 0.8. According to one embodiment, the RMK parameter as defined above is comprised from 0.1 to 1.25; from 0.2 to 1.25; from 0.3 to 1.25; from 0.4 to 1.25; from 0.5 to 1.25; from 0.6 to 1.25; from 0.7 to 1.25; from 0.8 to 1.25; from 0.9 to 1.25; from 1 to 1.25. According to one embodiment, the RMK parameter as defined above is comprised from 0.1 to 1.25; from 0.1 to 1.2; from 0.1 to 1.25; from 0.1 to 1.1; from 0.1 to 1; from 0.1 to 0.9; from 0.1 to 0.8; from 0.1 to 0.7; from 0.1 to 0.6; from 0.1 to 0.5; from 0.1 to 0.4; from 0.1 to 0.3; or from 0.1 to 0.2. According to one embodiment, the RMK parameter as defined above is within a range of 0.20 to 0.80; preferably from 0.25 to 0.80; 0.30 to 0.80; 0.35 to 0.80; 0.40 to 0.80; 0.45 to 0.80; 0.50 to 0.80; 0.55 to 0.80; 0.60 to 0.80; 0.65 to 0.80; or 0.70 to 0.80.According to one embodiment, the RM K parameter as defined above is within a range of 0.20 to 0.80; preferably 0.20 to 0.75; 0.20 to 0.70; 0.20 to 0.65; 0.20 to 0.60; 0.20 to 0.55; 0.20 to 0.50; 0.20 to 0.45; 0.20 to 0.40; 0.20 to 0.35; 0.20 to 0.30; or 0.20 to 0.25.

[0058] The parameter Sat(CH) as defined above, is comprised in a range of 0.75 to 8; preferably from 1 to 8; from 2 to 8; from 3 to 8; from 4 to 8; from 5 to 8; from 6 to 8; or from 7 to 8. According to one embodiment, the parameter Sat(CH) is equal to 1, 2, 3, 4, 5, 6, 7 or 8. According to one embodiment, the parameter Sat(CH) as defined above, is comprised in a range of from 0.75 to 7; from 0.75 to 6; from 0.75 to 5; from 0.75 to 4; from 0.75 to 3; from 0.75 to 2; or from 0.75 to 1. In the present invention, the level of calcium hydroxide in these limes can be determined by any methods known to those skilled in the art such as for example the Leduc method (Hornain, 1995). Ettringitic binder

[0059] The invention relates to an ettringitic binder. In particular, the invention relates to an ettringitic binder obtainable from the process of the invention as described above.

[0060] According to one embodiment, the ettringitic binder is obtained from the mixture of at least: at least one source of aluminosilicate as described above; at least one source of calcium sulfate as described above; at least one source of calcium hydroxide as described above; and at least one alkaline catalyst chosen from sodium fluoride, sodium aluminate, trisodium phosphate, sodium orthosilicate, sodium metasilicate, sodium hexafluorosilicate, sodium fluorophosphate, sodium hexametaphosphate, sodium carbonate, sodium borate, sodium hexafluoroaluminate, potassium tetrafluoroaluminate or mixtures thereof; at least one activator as described above, preferably chosen from compounds capable of complexing cations, preferably compounds capable of complexing calcium, aluminum and / or silicon.

[0061] The ettringitic binder has an RMK parameter as defined above, comprised in a range of 0.05 to 1.25; preferably from 0.1 to 1; more preferably from 0.2 to 0.8. According to one embodiment, the RMK parameter as defined above, is comprised from 0.1 to 1.25; from 0.2 to 1.25; from 0.3 to 1.25; from 0.4 to 1.25; from 0.5 to 1.25; from 0.6 to 1.25; from 0.7 to 1.25; from 0.8 to 1.25; from 0.9 to 1.25; from 1 to 1.25. According to one embodiment, the RMK parameter as defined above, is comprised from 0.1 to 1.25; from 0.1 to 1.2; from 0.1 to 1.25; from 0.1 to 1.1; from 0.1 to 1; from 0.1 to 0.9; from 0.1 to 0.8; from 0.1 to 0.7; from 0.1 to 0.6; from 0.1 to 0.5; from 0.1 to 0.4; from 0.1 to 0.3; or from 0.1 to 0.2. According to one embodiment, the RMK parameter as defined above is within a range of 0.20 to 0.80; preferably from 0.25 to 0.80; 0.30 to 0.80; 0.35 to 0.80; 0.40 to 0.80; 0.45 to 0.80; 0.50 to 0.80; 0.55 to 0.80; 0.60 to 0.80; 0.65 to 0.80; or 0.70 to 0.80.According to one embodiment, the RMK parameter as defined above is in a range of 0.20 to 0.80; preferably 0.20 to 0.75; 0.20 to 0.70; 0.20 to 0.65; 0.20 to 0.60; 0.20 to 0.55; 0.20 to 0.50; 0.20 to 0.45; 0.20 to 0.40; 0.20 to 0.35; 0.20 to 0.30; or 0.20 to 0.25.

[0062] The ettringitic binder has a Sat(CH) parameter as defined above, comprised in a range of 0.75 to 8; preferably 1 to 8; 2 to 8; 3 to 8; 4 to 8; 5 to 8; 6 to 8; or 7 to 8. According to one embodiment, the Sat(CH) parameter is equal to 1, 2, 3, 4, 5, 6, 7 or 8. According to one embodiment, the Sat(CH) parameter as defined above, is comprised in a range of 0.75 to 8; 0.75 to 7; 0.75 to 6; 0.75 to 5; 0.75 to 4; 0.75 to 3; 0.75 to 2; or 0.75 to 1. Uses

[0063] The invention also relates to the use of the ettringitic binder of the invention for the preparation of construction materials.

[0064] According to one embodiment, the ettringitic binder of the invention is used for the preparation of cement, masonry cement, road binder, concrete, mortar and / or formulated lime. Building material

[0065] A material is obtained by hydration of the ettringitic binder of the invention.

[0066] During the hydration of the ettringitic binder, two chemical reactions are implemented allowing the production of ettringite: (1) Reaction between lime and aluminosilicate leading to the formation of calcium aluminate (C4AH13 in cement notation) AS2 + 4 CH → C4AH13 + 2S (2) Reaction of the calcium aluminate formed in (1) with calcium sulfate leading to the formation of ettringite C4AH13 + 3 C$ → C6A$3H32 + CH

[0067] The balanced equation for the hydration reaction of the ettringitic binder is: AS2 + 5CH +3 C$ → C6A$3H32 + 2CSH

[0068] In the present invention, the hydration of the ettringitic binder of the invention leads to a material whose density depends on the intended applications. According to one embodiment, the material of the invention has a density of more than 0 to 2.1 kg / L, preferably 1 to 2 kg / L, more preferably the density is approximately 1.9 kg / L. Advantageously, the density of the material of the invention is lower than those of materials obtained from Portland cement.

[0069] According to one embodiment, the material is a cement, a masonry cement, a road binder, a concrete, a mortar and / or a formulated lime.

[0070] According to one embodiment, the mechanical performances such as the compressive strength of a material obtained from the ettringitic binder of the invention are increased by 1% to 100%, preferably by 5% to 80%, more preferably by 40% to 70% compared to materials from conventional pozzolanic compositions such as those obtained from a mixture of aluminosilicate and lime.

[0071] According to one embodiment, the material further comprises an adjuvant, preferably chosen from curing agents and / or formwork release oils. The term “formwork release oil” means an oil spread on the formwork skins in order to facilitate the demolding of the concrete or mortar hardened in said formwork.

[0072] According to one embodiment, the material obtained from the ettringitic binder of the invention exhibits little or no shrinkage during its shaping.

[0073] According to one embodiment, the material obtained from the ettringitic binder of the invention does not comprise Portland cement.

[0074] According to one embodiment, the material obtained from the ettringitic binder of the invention has a 3-day compressive strength in a range of more than 0 to 60 MPa, preferably 2 to 45 MPa, more preferably 10 to 40 MPa. According to one embodiment, the material obtained from the ettringitic binder of the invention has a 3-day compressive strength in a range of more than 1 to 60 MPa, preferably 2 to 50 MPa, preferably 10 to 50 MPa, preferably 15 to 50 MPa, preferably 20 to 50 MPa, preferably 25 to 50 MPa, preferably 30 to 50 MPa, preferably 35 to 50 MPa, preferably 40 to 50 MPa, or preferably 45 to 50 MPa. According to one embodiment, the material obtained from the ettringitic binder of the invention has a 3-day compressive strength of approximately 14 MPa, 21 MPa, 23 MPa or 26 MPa.

[0075] According to one embodiment, the material obtained from the ettringitic binder of the invention has a 7-day compressive strength in a range of more than 0 to 60 MPa, preferably 2 to 45 MPa, more preferably 10 to 40 MPa. According to one embodiment, the material obtained from the ettringitic binder of the invention has a 7-day compressive strength in a range of more than 1 to 60 MPa, preferably 2 to 50 MPa, preferably 10 to 50 MPa, preferably 15 to 50 MPa, preferably 20 to 50 MPa, preferably 25 to 50 MPa, preferably 30 to 50 MPa, preferably 35 to 50 MPa, preferably 40 to 50 MPa, or preferably 45 to 50 MPa. According to one embodiment, the material obtained from the ettringitic binder of the invention has a 7-day compressive strength of approximately 11 MPa, 17 MPa, 18 MPa, 21 MPa, 27 MPa, 30 MPa, 31 MPa, 32 MPa, 33 MPa, 35 MPa, 42 MPa or 46 MPa.

[0076] According to one embodiment, the material obtained from the ettringitic binder of the invention has a compressive strength at 28 days in a range of more than 0 to 150 MPa, preferably 2 to 100 MPa, more preferably 20 to 90 MPa. According to one embodiment, the material obtained from the ettringitic binder of the invention has a compressive strength at 28 days in a range of more than 2 to 150 MPa, preferably 20 to 150 MPa, preferably 30 to 150 MPa, preferably 40 to 150 MPa, preferably 50 to 150 MPa, preferably 60 to 150 MPa, preferably 70 to 150 MPa, preferably 80 to 150 MPa, preferably 90 to 150 MPa, preferably 100 to 150 MPa, preferably 110 to 150 MPa, preferably 120 to 150 MPa, preferably 130 to 150 MPa, preferably 140 to 150 MPa.According to one embodiment, the material obtained from the ettringitic binder of the invention has a compressive strength at 28 days in a range of more than 2 to 150 MPa, preferably 2 to 140 MPa, preferably 2 to 130 MPa, preferably 2 to 130 MPa, preferably 2 to 120 MPa, preferably 2 to 120 MPa, preferably 2 to 110 MPa, preferably 2 to 100 MPa, preferably 2 to 90 MPa, preferably 2 to 80 MPa, preferably 2 to 70 MPa, preferably 2 to 60 MPa, preferably 2 to 50 MPa, preferably 2 to 40 MPa, preferably 2 to 30 MPa, preferably 2 to 20 MPa, According to one embodiment, the material obtained from the ettringitic binder of the invention has a compressive strength at 28 days of approximately 44 MPa, 52 MPa or 54 MPa.

[0077] According to one embodiment, the material obtained from the ettringitic binder of the invention has a flexural strength at 28 days in a range of more than 0 to 15 MPa, preferably 1 to 10 MPa, more preferably 2 to 9 MPa. According to one embodiment, the material obtained from the ettringitic binder of the invention has a flexural strength at 28 days in a range of more than 0 to 15 MPa, preferably 1 to 10 MPa, more preferably 2 to 6 MPa. According to one embodiment, the material obtained from the ettringitic binder of the invention has a flexural strength at 28 days in a range of more than 0 to 10 MPa, preferably 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 MPa.

[0078] In the present invention, the compressive strength tests were conducted on pre-molded compositions (cubic molds, 40 mm × 40 mm, or 10 cm × 10 cm) with the E0250 / 15 KN Controlab class A apparatus; or with cylindrical samples (16 cm × 32 cm). The compressive strength measurements were also carried out on walls with the Controlab sclerometer apparatus. Process for preparing a construction material

[0079] The method for preparing a construction material comprises a step of mixing the ettringitic binder as described above, with water.

[0080] The method of preparing a construction material further comprises a step of shaping the material.

[0081] The method for preparing a building material from the ettringitic binder of the invention does not include the use of Portland cement. The method for preparing a building material from the ettringitic binder of the invention does not include the use of calcium sulfoaluminate. BRIEF DESCRIPTION OF THE FIGURES

[0082] Figure 1 is a graph showing the percentage gain in mechanical performance after 28 days, for an ettringitic binder of the invention compared to those of a conventional pozzolanic composition, as a function of the value of the RMK parameter. Figure 2 presents a graph showing the percentage gain in mechanical performance after 3 days (solid line) or after 7 days (dotted line), for an ettringitic binder of the invention compared to those of a conventional pozzolanic composition, as a function of the value of the RMK parameter. EXAMPLES

[0083] The present invention will be better understood by reading the following examples which illustrate the invention in a non-limiting manner. Abbreviations

[0084] A: in cement notation, designates aluminum oxide (Al 2 O 3 ) or alumina; AS2: in cement notation, designates a metakaolin; C: in cement notation, designates calcium oxide (CaO); CH: in cement notation, designates calcium hydroxide (Ca(OH) 2 ); CSH2: in cement notation, designates gypsum; C4AH13: in cement notation, designates tetracalcium aluminate; CxSH: in cement notation, designates a calcium silicate where x varies from 1 to 3, preferably from 1.2 to 2.5; C2ASH8: in cement notation, designates hydrated gehlenite; C4A3$: in cement notation, designates yelem'nite; C2S: in cement notation, designates belite; CS: in cement notation, designates calcium sulfate; C6A$3H32: in cement notation designates ettringite; C4A$H20: in cement notation designates tricalcium alumino-monosulfate; CL: natural aerial lime (“Calcic lime”); DSF: desulfogypsum; E / L: mass ratio of water to binder;IPZ: pozzolanic index of the metakaolin used; L / T: mass ratio of binder to total dry matter (binder, additives, etc.); MK: metakaolin; MSLKL: sodium metasilicate pentahydrate; NaHFS: sodium hexafluorosilicate; NaHFA: sodium hexafluoroaluminate; NaAlO 2: sodium aluminate; NaF: sodium fluoride; P: quarry gypsum; P(C$): purity of the calcium sulfate source; R: demolition gypsum; RMK: the quantity of calcium sulfate relative to the quantity of metakaolin, introduced into the initial mixture and defined according to equation (e3); S: in cement notation, designates silicon dioxide (SiO 2 ) or silica; $: in cement notation, designates sulfur trioxide (SO- 3 ); Sc: dryness in the mixture; H: in cement notation designates water (H 2 O); Sat(CH): the mass saturation of calcium hydroxide, Ca(OH) 2 in a given composition; TEA: triethanolamine. Materials and Methods Material

[0085] The aluminosilicates and metakaolins were supplied by Argeco (Argicem ®< product) or by Imerys (Argical M1000 ®< products, Argical M1200S, MetaStar M501), by Soka (Soka Metasial ®< ) or are fines from the chamotte industry or were manufactured in the laboratory according to conventional protocols.

[0086] Various limes were supplied by LHOIST (LHOIST lime ®< CL80, LHOIST lime ®< CL90, LHOIST Sorbacal lime ®< ) or by CESA (Decorchaux ®< CL90 slaked air lime). The calcium hydroxide content in these limes was determined by the Leduc method (Hornain, 1995).

[0087] Various sources of calcium sulfate, such as gypsum, were tested. The products were obtained from various suppliers known to those skilled in the art. Characteristics of the mixture of the invention

[0088] The binder of the invention is characterized by the parameters as defined below. The pozzolanic index (PIZ) is a parameter representing the active fraction of a metakaolin, i.e. the quantity of calcium hydroxide, Ca(OH) 2 , which can be fixed in one gram of metakaolin. This index can be determined by methods known to those skilled in the art such as, for example, the Chapelle test.

[0089] The parameter Sat(CH) represents the mass saturation rate of calcium hydroxide, Ca(OH) 2 in a given composition. It is determined according to the following equation (e1): Or : Q(CH) represents the quantity in grams of calcium hydroxide (Ca(OH)2) in the binder; and QST(CH) represents the quantity in grams of calcium hydroxide required for the ettringite formation reaction. The parameter QST(CH) can be determined according to the following equation (e2): where: IPZ represents the pozzolanic index as defined previously; Q(MK) represents the quantity in grams of metakaolin or aluminosilicates present in the binder; and P(CH) represents the purity of the lime in calcium hydroxide.

[0090] The RMK parameter represents the stoichiometric ratio of calcium sulfate to the amount of aluminosilicates such as metakaolin, introduced into the initial mixture. The QST(CH) parameter can be determined according to the following equation (e3): Or : IPZ represents the pozzolanic index as defined previously; Q(MK) represents the quantity in grams of metakaolins or aluminosilicates present in the binder; and Qm(C$) represents the quantity in moles of calcium sulfate _ present in the binder. The parameter Qm(C$) can be determined according to the following equation (e4): where: Q(G) represents the quantity in grams of calcium sulfate source introduced into the initial mixture; P(C$) represents the mass purity of the calcium sulfate source; Sc represents the dryness, i.e. the mass percentage of dry matter contained in the mixture. Compressive strength

[0091] Compressive strength tests were conducted on pre-molded compositions (cubic molds, 40 mm × 40 mm, or 10 cm × 10 cm) with the E0250 / 15 KN Controlab class A apparatus; or with cylindrical samples (16 cm × 32 cm).

[0092] Compressive strength measurements were also carried out on walls using the Controlab sclerometer device. PART A: COMPOSITIONS Example 1: Preparation of an ettringitic binder according to the process of the invention General protocol

[0093] The ettringitic binders of the invention were prepared at room temperature, by mixing an aluminosilicate, a calcium sulfate and lime in proportions such that the RMK ratio as defined above is within a range of 0.05 to 1.25; and that the lime saturation parameter, Sat(CH), is within a range of 0.75 to 8.

[0094] According to the invention, to this mixture (aluminosilicate / calcium sulfate / lime) are added (i) alkaline catalysts, (ii) reaction activators. Optionally, secondary additives, such as fillers, preferably limestone fillers, can be added. Examples of mixtures of the invention comprising an aluminosilicate, a sulfate of calcium and lime

[0095] Examples of catalysts

[0096] Catalysts were also added to the mixtures 1 has 11 as described previously (Table 1).

[0097] The catalysts used were chosen from: sodium fluoride, sodium hexafluoroaluminate, sodium hexafluorosilicate, sodium fluorophosphate, potassium tetrafluoroaluminate, sodium metasilicate, sodium orthosilicate, sodium trisilicate, sodium disilicate, sodium aluminate, sodium phosphate, sodium carbonate, and sodium sulfate. Examples of activators

[0098] Activators were also added to the mixtures 1 has 11 as described previously (Table 1). The activators used were chosen from compounds capable of complexing cations, in particular calcium, such as sucrose, tartaric acid, citric acid, gluconic acid, mandelic acid, lactic acid, or an ethanolamine such as triethanolamine (TEA). Example 2: Preparation of a material from the ettringitic binder of the invention

[0099] Various materials could be obtained by mixing the ettringitic binder of the invention with a quantity of water, this being modulated according to the intended applications.

[0100] During the hydration of the ettringitic binder, two chemical reactions are implemented allowing the production of ettringite: (1) Reaction between lime and aluminosilicate leading to the formation of calcium aluminate (C4AH13 in cement notation) AS2 + 4 CH → C4AH13 + 2S (2) Reaction of the calcium aluminate formed in (1) with calcium sulfate leading to the formation of ettringite C4AH13 + 3 C$ → C6A$3H32 + CH

[0101] The balanced equation for the hydration reaction of the ettringitic binder is: AS2 + 5CH +3 C$ → C6A$3H32 + 2CSH

[0102] The following examples present the performances for materials obtained from the ettringitic binder of the invention. Example 3: Preparation of a material from an ettringitic binder comprising a metakaolin / lime / gypsum mixture without catalysis or activation and performance of this material (reference example)

[0103] The aim of this experiment is to show the performance of a material resulting from the hydration of an ettringitic binder obtained from a mixture of metakaolin, lime and gypsum whose Sat(CH) parameter is between 1 and 1.1 for different values ​​of the RMK parameter as defined above.

[0104] For this, a comparison was carried out between a material derived from the ettringitic binder obtained by mixing: ARGICEM ® flashed metakaolin with an IPZ of between 700 and 800 mg / g; a CL90 type slaked lime with a LEDUC lime content of approximately 90%; and gypsum; and a material from a classic pozzolanic composition (i.e. mixture of lime and metakaolins).

[0105] There Figure 1presents a graph showing the percentage gain in mechanical performance after 28 days of the mixture of the invention compared to that of a conventional pozzolanic composition, as a function of the value of the RMK parameter.

[0106] The results show that: for RMK values ​​between 0 and 1, a performance gain is always observed for the material derived from the ettringitic binder; and for RMK values ​​between 0.25 and 0.75 a gain greater than 40% is obtained compared to the performance of a classic pozzolanic composition.

[0107] In conclusion, these results demonstrate that the above mixture makes it possible to significantly increase the mechanical performance after 28 days of the product obtained from the binder of the invention. Furthermore, the Applicant noted in additional experiments that from an RMK value of 0.6, an additional gain could be obtained depending on the nature of the gypsum. Performance at an early age

[0108] One of the major drawbacks of a classic pozzolanic binder (i.e. a mixture of lime and metakaolin) obtained from Portland cement is its very slow setting (or hardening) speed, resulting in poor mechanical performance at an early age.

[0109] A study was therefore carried out to evaluate the performance of the ettringitic binder over shorter times, namely 3 days (D+3) or 7 days (D+7) after the preparation of the mixture comprising: ARGICEM ® flashed metakaolin with an IPZ of between 700 and 800 mg / g; a CL90 type slaked lime with a LEDUC lime content of approximately 90%; and gypsum.

[0110] There Figure 2 presents a graph showing the percentage gain in mechanical performance after 3 days or after 7 days, for an ettringitic binder obtained from the above mixture compared to those of a classic pozzolanic composition, as a function of the value of the RMK parameter.

[0111] The results show that results are comparable to those obtained after 28 days. Indeed, we also observe that: for RMK values ​​between 0.3 and 0.7 a gain greater than 40% is obtained compared to the performance of a classic pozzolanic composition; and for values ​​greater than 0.7, a strong reduction in gain is observed.

[0112] In conclusion, these results demonstrate that the above mixture makes it possible to obtain very quickly an ettringitic binder with good mechanical performance (compressive strength) even at short times, times for which conventional pozzolana compositions do not provide acceptable mechanical resistance for their use as construction materials. Example 4: Preparation of a material from an ettringitic binder comprising a metakaolin / lime / gypsum mixture in the presence of a catalyst and an activator - Comparison of RMKs

[0113] The aim is to compare the performance of a material obtained from a binder of the invention, for RMK values ​​greater than 0.6.

[0114] For this purpose, a material was prepared by hydration of an ettringitic binder comprising Argical M1000 ®< / quarry calcium sulfate / CL90 lime in the presence of catalyst and activator. The Sat(CH) parameter is 1.07-1.1. The water / binder ratio is approximately 0.53. The compressive strength (RC) at 28 days was measured for two RMK values:

[0115] These results show that an additional gain is obtained for RMK values ​​greater than 0.6 when the material is prepared from an ettringitic binder comprising a catalyst and an activator. Example 5: Preparation of a material from an ettringitic binder comprising a metakaolin / lime / gypsum mixture in the presence of a catalyst and performance of this material

[0116] The aim of this experiment is to study the mechanical performance of an ettringitic binder obtained from a metakaolin / lime / gypsum mixture with or without an alkaline catalyst.

[0117] The metakaolin / lime / gypsum mixture is characterized by an RMK value equal to 0.67 and a Sat(CH) value approximately equal to 1.03.

[0118] Various catalysts were tested: sodium fluoride, sodium aluminate, trisodium phosphate, sodium orthosilicate and sodium metasilicate, and sodium hexafluorate.

[0119] Compressive strength (CS) was measured 3 days (D+3) or 7 days (D+7) after mixture preparation. The results are presented in the Table 2 below.

[0120] A study was also conducted by varying the nature of the gypsum and the values ​​of the RMK parameter. The results obtained after 7 days (D+7) and 28 days (D+28) are presented in the Table 3 below.

[0121] The results show that the addition of an alkaline catalyst in the mixture makes it possible to increase the compressive strength at short times (D+7) or longer times (D+28). Example 6: Preparation of a material from an ettringitic binder comprising a metakaolin / lime / gypsum mixture in the presence of a catalyst and an activator and performance of this material

[0122] The progress of the ettringite formation reaction depends on the supply of calcium aluminate formed by the reaction between the aluminosilicate source and the calcium oxide source (lime). However, the mechanical performance of the material obtained from the ettringitic binder of the invention depends on the reaction efficiency between the calcium aluminate and the calcium sulfate source (such as gypsum).

[0123] The Applicant therefore sought to optimize the mixture of the invention in order to provide better yields and higher compressive strengths.

[0124] Various compounds were tested on a mortar basis. The mortar formulation consists of mixing sand, water and the ettringitic binder of the invention comprising a mixture of: flashed metakaolin ARGICEM ®< of IPZ approximately equal to 700 mg / g; slaked lime of type CL90 with LEDUC lime content of approximately 90%; and desulfogypsum; and NaAlO 2 (1.3%) as catalyst; in which the RMK parameter is equal to 0.82; the Sat(CH) parameter is equal to 1.03.

[0125] The mortar has a sand to binder ratio (SBR) of 0.33. The water to binder ratio (W / B) is between 0.47 and 0.55.

[0126] Surprisingly, the Applicant has demonstrated that compounds capable of complexing calcium such as sucrose and / or alpha-hydroxy acids make it possible to obtain improved compressive strengths after 7 and 28 days compared to the reference formulation. M1 (Cf. Table 4 ). PART B: USES OF ETTRINGITE BINDER FOR THE MANUFACTURE OF BUILDING MATERIALS Example 7: Cement preparation

[0127] The Applicant prepared cements 3-5 from the ettringitic binder of the invention.

[0128] Cements 1 and 2 are comparative.

[0129] The water to binder ratio (W / B) is 0.5. The formulations and results are presented in the Table 5 below.

[0130] Flexural and compressive strengths were conducted using 4×4×16 mm specimens. The results show that the performance of these cements meets the compressive strength values ​​required by the EN-196 standard. Example 8: Preparation of road binder

[0131] The Applicant has prepared several road binders from the ettringitic binder of the invention.

[0132] The objective is to provide a road binder capable of meeting the mechanical resistance objectives set by standard NF P15-108, namely to obtain a load-bearing value (EV2 modulus) greater than 50MPa.

[0133] The bearing capacity was determined using the "plate test". This method consists of applying a stress to a surface of standardized diameter and rigidity in order to measure its penetration into the ground. This method allows the determination of the Westergraad reaction coefficient (Kw), the bearing capacity modules EV1 and EV2, as well as the compaction ratio (EV2 / EV1).

[0134] The binder of the invention studied comprises a mixture of: 600 kg / tonne of binder, flashed metakaolin ARGICEM ®< of IPZ approximately equal to 700 mg / g; 300 kg / tonne of binder, slaked lime of type CL90 with LEDUC lime content of approximately 90%; and 100 kg / tonne of binder, gypsum; in which the RMK parameter is equal to 0.27; the Sat(CH) parameter is equal to 1.03.

[0135] For this purpose, a clay-sandy soil with a surface area of ​​250 m 2 and a depth of 40 cm was mechanically stabilized with the binder of the invention. The dosage is between 35 and 40 kg of road binder per square meter. After 28 days, the EV2 bearing capacity was measured on this stabilized soil. The results are presented in the Table 6.

[0136] The results show that EV2 moduli are greater than 50 MPa.

[0137] Therefore, these results confirm that the binder of the invention can be used as a road binder while meeting the requirements of standard NF P15-108. Example 9: Mortar preparation

[0138] The Applicant prepared the mortars MRT1, MRT2, MRT6 and MRT7 from the ettringitic binder of the invention. The mortars MRT3 and MRT4 are comparative.

[0139] THE Table 7presents some examples of mortars prepared by the Applicant from the binder of the invention. In this table, the quantities are expressed in kg per tonne of binder.

[0140] These mortars were used as rendering mortars on various substrates such as concrete or plaster, or as assembly mortars on concrete block, hollow brick, biobrick and natural stone substrates. After 8 months of observation, no incompatibilities were visually detected. Example 10: Concrete preparation _

[0141] The Applicant prepared concretes B1, B2 and B4 from the ettringitic binder of the invention. Concrete B3 is comparative.

[0142] THE Table 8 presents some examples of concretes prepared by the Applicant from the binder of the invention. In this table, the quantities are expressed in kg per tonne of binder. Example 11: Preparation of masonry cements and formulated limes

[0143] The Applicant prepared several masonry cements and lime (reference example).

[0144] To be used as masonry cement or formulated lime, the formulation must have a compressive strength after 28 days of at least 10 MPa for masonry cements; and at least 3.5 MPa in the case of formulated lime.

[0145] Table 9 shows some examples of masonry cements prepared by the Applicant.

[0146] In this table, the quantities are expressed in kg per tonne of binder.

[0147] The results show that excellent results are achieved within three days.

Claims

1. Ettringitic binder comprising: - at least one source of aluminosilicate characterized by a pozzolanic activity index (PIZ) determined by the Chapelle test method, in a range from 200 to 2200 mg / g; - at least one source of calcium sulfate; - at least one source of calcium hydroxide; - at least one alkaline catalyst chosen from sodium fluoride, sodium aluminate, trisodium phosphate, sodium orthosilicate, sodium metasilicate, sodium hexafluorosilicate, sodium fluorophosphate, sodium hexametaphosphate, sodium carbonate, sodium borate, sodium hexafluoroaluminate, potassium tetrafluoroaluminate or mixtures thereof; and - at least one activator selected from compounds capable of complexing cations, preferably compounds capable of complexing calcium, aluminum and / or silicon; said ettringitic binder being characterized by - a calcium hydroxide saturation rate, denoted Sat(CH), in a range from 0.75 to 8; and - a calcium sulfate rate, denoted RMK, in a range from 0.05 to 1.25; the RMK parameter being defined by the following equation RMK = Qm C $ × 592000 IPZ × Q MK × 3 wherein: IPZ represents the pozzolanic index of the aluminosilicate source; Q(MK) represents the quantity in grams of aluminosilicates present in the ettringitic binder; and Qm(C$) represents the amount in moles of calcium sulfate present in the ettringitic binder.

2. Ettringitic binder according to claim 1, in which the activator is selected from sucrose, alpha-hydroxy acids or their salts, ethanolamines or their salts, and / or catechols or its derivatives.

3. Ettringitic binder according to claim 1 or claim 2, in which the amount of catalyst is in a range of more than 0% to 20% by mass relative to the total amount of the binder.

4. Ettringitic binder according to any one of claims 1 to 3, in which the source of aluminosilicate is a pozzolan, a fine from the production of chamotte or ash from paper mill sludge, preferably a metakaolin.

5. Ettringitic binder according to any one of claims 1 to 4, wherein the source of calcium hydroxide is slaked lime, hydraulic lime, quicklime, delayed quicklime, air lime, conventional slaked lime or any commercial lime.

6. Ettringitic binder according to any one of claims 1 to 5, wherein the source of calcium sulfate is selected from anhydrite, natural gypsum or gypsum obtained as a by-product of industrial reactions such as desulfogypsum, titanogypsum, fluogypsum or phosphogypsum.

7. Ettringitic binder according to any one of claims 1 to 6, further comprising additives, preferably slags, more preferably blast furnace slags or amorphous aluminate slags.

8. Process for preparing an ettringitic binder according to any one of claims 1 to 7, comprising mixing at least: - a source of aluminosilicate characterized by a pozzolanic activity index (PIZ) determined by the Chapelle test method, in a range of 200 to 2200 mg / g; - a source of calcium sulfate; - a source of calcium hydroxide; - at least one alkaline catalyst chosen from sodium fluoride, sodium aluminate, trisodium phosphate, sodium orthosilicate, sodium metasilicate, sodium hexafluorosilicate, sodium fluorophosphate, sodium hexametaphosphate, sodium carbonate, sodium borate, sodium hexafluoroaluminate, potassium tetrafluoroaluminate or mixtures thereof; and - at least one activator chosen from compounds capable of complexing cations, preferably compounds capable of complexing calcium, aluminum and / or silicon, said mixture having: - a saturation rate of calcium hydroxide, denoted Sat(CH), in a range from 0.75 to 8; and - a calcium sulfate rate, denoted RMK, in a range from 0.05 to 1.25; the parameters RMK and Sat(CH) being defined according to claim 1.

9. Preparation process according to claim 8, in which the temperature at which the mixing is carried out is from more than 0°C to 50°C, preferably from 10°C to 40°C, more preferably at approximately 25°C.

10. Use of the ettringitic binder according to any one of claims 1 to 7, for the preparation of cements, masonry cements, mortars, concretes, road binders and / or formulated lime.