WO2017068288A1 - Use of polyacrylamide in a hydraulic composition for improved carbonation resistance - Google Patents

Use of polyacrylamide in a hydraulic composition for improved carbonation resistance Download PDF

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Publication number
WO2017068288A1
WO2017068288A1 PCT/FR2016/052710 FR2016052710W WO2017068288A1 WO 2017068288 A1 WO2017068288 A1 WO 2017068288A1 FR 2016052710 W FR2016052710 W FR 2016052710W WO 2017068288 A1 WO2017068288 A1 WO 2017068288A1
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Prior art keywords
polyacrylamide
binder
hydraulic
hydraulic composition
crosslinked
Prior art date
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PCT/FR2016/052710
Other languages
French (fr)
Inventor
Alexandre JACQUEMIN
Lê-Chiên HOANG
Rémi BARBARULO
Blandine ALBERT
David Rinaldi
Original Assignee
Lafarge
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Publication of WO2017068288A1 publication Critical patent/WO2017068288A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
    • C04B24/24—Macromolecular compounds
    • C04B24/26—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • C04B24/2652—Nitrogen containing polymers, e.g. polyacrylamides, polyacrylonitriles
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
    • C04B28/04—Portland cements
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
    • C04B2103/0045—Polymers chosen for their physico-chemical characteristics
    • C04B2103/0062—Cross-linked polymers
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/20—Resistance against chemical, physical or biological attack
    • C04B2111/22—Carbonation resistance
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/20—Resistance against chemical, physical or biological attack
    • C04B2111/26—Corrosion of reinforcement resistance
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

  • the present invention relates to the field of construction materials, and more particularly to the use of an additive in a hydraulic composition to improve the resistance to carbonation and thus improve the durability of the structure resulting from the hardening of the composition hydraulic.
  • the durability of concrete or mortar structures obtained by hardening a hydraulic composition is a major concern. Indeed, a work must withstand over time to the various aggressions or solicitations (physical, mechanical, chemical, ...), that is to say to the loads to which it is subjected, as well as wind, to the rain, cold, heat or environment. However exposure to the ambient atmosphere can cause the carbonation of the material resulting from the hardening of a hydraulic composition. Indeed, the amount of water introduced into the hydraulic composition in the fresh state is often greater than the stoichiometric amount, which leads to a porous medium whose pores are first filled with water. When the cementitious material dries, it becomes desaturated in water and the pores partially fill with air.
  • the atmospheric CO 2 thus diffuses into the hydraulic composition hydrated by its porosity and reacts with the hydrates of the cement, in particular with portlandite, to form calcium carbonate. This results in a drop in pH, which generally goes from a value of 13 in the non-carbonated zone to a value generally less than 9 in the carbonated zone.
  • the pH of the degraded zone of the hardened hydraulic composition decreases and initiates the corrosion of the steels in a humid medium and in the presence of oxygen.
  • Carbonation is a major problem for hydraulic compositions with low clinker content. Indeed, during hardening, these hydraulic compositions are very sensitive to carbonation because of their low rate of Portlandite (phase created during the hydration of a clinker, especially Portland), this phase playing a buffer role in the progression carbonation. In order to meet the requirements of the users, it has become necessary to find a means for reducing or preventing carbonation, and thus the corrosion of metal elements when they are present, in the hydraulic compositions in the cured state, in particular the compositions hydraulic systems with low clinker content and mineral additions.
  • the problem to be solved by the invention is to provide a means for reducing or preventing carbonation, and thus the corrosion of metal elements when present, in the hydraulic compositions in the cured state, in particular the compositions hydraulic systems with low clinker content and mineral additions.
  • the present invention seeks to reduce or prevent carbonation at a given stage of the hydration, which is characterized by the same mechanical resistance in compression (iso-resistance). Without being bound by theory, it would seem that carbonation is strongly linked to the progress of hydration.
  • the present invention relates to the use of at least one crosslinked polyacrylamide, in the form of a powder of particles having an average size of 300 ⁇ to 2,000 ⁇ , said crosslinked polyacrylamide having a degree of nitrogen greater than or equal to 4% by weight relative to the mass of said polyacrylamide, in combination with at least one hydraulic binder in a hydraulic composition, for reducing and / or preventing carbonation within said hydraulic composition, said polyacrylamide (s) ( s) crosslinked being present in said hydraulic composition in a weight ratio polyacrylamide (s) crosslinked (s) / binder of 0.01% to 5.0%.
  • the present invention relates to the use of at least one crosslinked polyacrylamide, in the form of a powder of particles having a mean size of from 300 ⁇ to 2,000 ⁇ , said crosslinked polyacrylamide having a degree of nitrogen greater than or equal to 4% by weight relative to the mass of said polyacrylamide, in combination with at least one hydraulic binder in a fresh hydraulic composition, said at least one crosslinked polyacrylamide (s) being present (s); ) in said hydraulic composition in a weight ratio of polyacrylamide (s) crosslinked (s) / binder of 0.01% to 5.0%, for reducing and / or preventing carbonation within said hydraulic composition in the cured state .
  • the inventors have demonstrated that the use of one (or more) crosslinked polyacrylamide added directly to the mass of a hydraulic composition makes it possible to reduce and / or prevent the carbonation of the composition in the cured state. and thus to improve the durability of the hydraulic composition and to reduce the corrosion of the metal reinforcements.
  • the hydraulic composition has improved resistance to carbonation
  • the metal reinforcements present in the hydraulic composition are not or only slightly corroded
  • the coating (as defined in standard NF EN 1992-1-1 of October 2005, paragraph 4.4.1.1) of the reinforcements becomes less critical and the positioning of the reinforcements in the thickness of the hydraulic composition is facilitated;
  • the hydraulic composition may comprise a reduced rate of clinker, without this promoting the corrosion of the metal reinforcements;
  • the hydraulic composition makes it possible to form a barrier to gases other than CO 2 (for example radon, chlorine, and oxygen), as well as a liquid barrier.
  • gases other than CO 2 for example radon, chlorine, and oxygen
  • the present invention is particularly applicable to reinforced concretes, in particular reinforced concrete based on hydraulic composition having a low level of clinker.
  • hydroaulic binder means a dry material that takes and hardens by hydration.
  • the setting is the transition from liquid or pasty state to solid state.
  • the setting is followed or accompanied by a curing phenomenon during which the material acquires mechanical properties. Hardening usually occurs after the end of setting, especially for cements.
  • a hydraulic binder generally comprises a clinker, calcium sulfate, and one or more mineral additions, in particular as detailed below.
  • a hydraulic composition according to the invention preferably further comprises water.
  • hydraulic composition means a composition comprising a hydraulic binder, water, possibly in the hardened state of the elements. metal, possibly aggregates and possibly adjuvants.
  • the hydraulic composition of the invention is a concrete, more particularly an reinforced concrete.
  • the amount of water is such that the water / binder mass ratio is preferably from 0.4 to 1.2 and preferably from 0.4 to 0.7.
  • a hydraulic composition according to the invention includes both the compositions in the fresh state, for example a cement slurry, and in the cured state, for example a mortar or a concrete.
  • the fresh hydraulic composition comprises water for hydration of the binder, while the cured hydraulic composition is obtained after hydration to give concrete or mortar.
  • the hydraulic composition according to the invention comprises at least one crosslinked polyacrylamide.
  • the crosslinked polyacrylamides according to the invention are capable of swelling in a hydraulic composition by absorbing water.
  • the presence of one or more crosslinked polyacrylamide (s) in a hydraulic composition is particularly beneficial to reduce the carbonation rate of said composition.
  • the hydraulic composition of the invention which incorporates at least one crosslinked polyacrylamide, has a greater resistance to carbonation than a reference hydraulic composition free of crosslinked polyacrylamide, which makes it possible to improve the durability of said hydraulic composition and of reduce the corrosion of any metal reinforcements.
  • a reference hydraulic composition free of crosslinked polyacrylamide which makes it possible to improve the durability of said hydraulic composition and of reduce the corrosion of any metal reinforcements.
  • a polyacrylamide that is suitable for the invention may comprise amide units and anionic, cationic or nonionic units, different from the amide units.
  • This type of polyacrylamide can be obtained by polymerization of a monomer mixture comprising acrylamide monomer units and anionic, cationic or nonionic comonomers, different from the acrylamide monomers.
  • the nonionic monomer units may for example be chosen from vinyl acetate and vinyl alcohol.
  • the anionic monomer units may for example be selected from the group consisting of alkali or ammonium salts of methacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, or maleic acid.
  • the cationic monomer units can be, for example, chosen from the group consisting of (meth) acrylamidoethyltrimethylammonium chloride and (meth) acrylamidopropyltrimethylammonium chloride.
  • a polyacrylamide that is suitable for the invention may comprise amide units and carboxylic acid and / or carboxylate units.
  • carboxylate is meant in particular alkali metal carboxylate, particularly sodium or potassium, or ammonium carboxylate.
  • carboxylic acid or carboxylate units can be generated from the acrylamide monomeric units by hydrolysis.
  • the polyacrylamides are obtained by polymerization of acrylamide monomers and then by hydrolysis.
  • carboxylic acid or carboxylate units can also come from monomeric units acrylic acid or acrylate.
  • the polyacrylamides are obtained by copolymerization of acrylamide monomers and acrylic acid and / or acrylate monomers.
  • a polyacrylamide comprises amide units and carboxylic acid and / or carboxylate units in an amide / (acrylic and / or acrylate) molar ratio of from 0.20 to 9.0.
  • crosslinked polyacrylamide a homopolymer or copolymer of acrylamide as described above, obtained by polymerization of a mixture comprising at least one acrylamide monomer and at least one crosslinking agent.
  • a crosslinking agent in the mixture makes it possible to connect the polyacrylamide chains to one another and to create a three-dimensional network of polyacrylamide chains.
  • a crosslinked polyacrylamide thus consists essentially of linear segments, crosslinked with each other, some of whose carbon atoms carry an amide group (optionally hydrolysed), contributing to the hydrophilic nature of the crosslinked polyacrylamide.
  • the degree of crosslinking of a crosslinked polyacrylamide increases with the proportion of crosslinking agent in the monomer mixture.
  • the crosslinked polyacrylamides according to the invention are preferably obtained from monomer mixtures comprising from 0.1% to 20%, preferably from 1% to 10%, advantageously from 2% to 5% of crosslinking agent (s). (s) by weight relative to the total weight of the monomer mixture.
  • the crosslinked polyacrylamides are hydrophilic but non-water-soluble gels, and this hydrophilic nature results in superabsorbent properties advantageously used in the context of the present invention.
  • crosslinked polyacrylamide adapted to the implementation of the invention, mention may be made of acrylamide / alkali metal acrylate copolymers, such as, for example, acrylamide / sodium or potassium acrylate copolymers, in particular polyacrylamide Aquasorb 3005. Max from the SNF company.
  • the nitrogen content of a polyacrylamide may be variable and is generally greater than or equal to 4% by weight relative to the mass of said polyacrylamide.
  • the nitrogen dosage of a polyacrylamide can be measured by a NOT-meter with a solid combustion chamber.
  • Polyacrylamide is first oxidized to form nitrogen oxides. These oxides are then reduced to NO. This NO is sent to a reaction chamber containing ozone O3 in excess; there is then light emission proportional to the concentration of nitric oxide. The emitted light is measured by a photomultiplier and a signal, observable in the form of a peak, is obtained.
  • crosslinked polyacrylamide (s) suitable for the implementation of the invention have a nitrogen content greater than or equal to 4% by weight relative to the weight of said polyacrylamide.
  • the nitrogen content is from 4% to 18%, advantageously from 9% to 15% by weight relative to the weight of said polyacrylamide.
  • the crosslinked polyacrylamide (s) of the invention is (are) in the form of a powder of polymer particles having an average size of from 300 ⁇ to 2,000 ⁇ , preferably from 300 ⁇ to 1000 ⁇ , and advantageously from 350 ⁇ to 600 ⁇ .
  • the size of the crosslinked polyacrylamide particles is generally measured by sieving or laser particle size. This is called the maximum particle size.
  • Industrial production of the crosslinked polyacrylamide particles generally comprises the following steps:
  • a copolymerization step of at least two monomers (generally acrylic acid and acrylamide) in the presence of a crosslinking agent.
  • a spray drying step for the inverse emulsion polymerization or
  • a step of drying, grinding and sieving, for mass polymerization is a step of drying, grinding and sieving, for mass polymerization.
  • the copolymerization is carried out in bulk or in inverse emulsion.
  • the crosslinking agent may be glyoxal, 1,1,2,2-ethanetetrol, ⁇ , ⁇ '-methylenebisacrylamide, piperazine diacrylamide, ⁇ , ⁇ '-bisacrylylcystamine, or ⁇ , ⁇ '-diallyltartradiamide. .
  • the weight average molecular weight (Mw) of the polymers obtained is very high (> 10,000,000 g / mol).
  • the crosslinked polyacrylamides according to the invention are preferably obtained by mass polymerization according to the method described above.
  • the crosslinked polyacrylamide (s) is (are) present in the hydraulic composition in a weight ratio of from 0.01% to 5.0% relative to the weight of the binder.
  • the weight ratio of crosslinked polyacrylamide (s) relative to the binder is from 0.05% to 2.0%, from 0.05% to 1.0%, or else from 0.05% at 0.75%.
  • the weight ratio of crosslinked polyacrylamide (s) relative to the binder is from 0.1% to 0.50%, or from 0.1% to 0.35%.
  • composition of the invention may comprise a mixture of several crosslinked polyacrylamide (s), having different nitrogen levels or different particle sizes.
  • s crosslinked polyacrylamide
  • the clinker used according to the present invention may be a Portland clinker, a sulfo-aluminous clinker, an aluminous clinker, a belitic clinker, a sulpho-belitic clinker and mixtures thereof, preferably a Portland clinker.
  • a Portland clinker is obtained by high temperature clinkerisation of a mixture comprising in particular limestone and clay.
  • a Portland clinker is a clinker as defined in standard NF EN 197-1 of February 2001.
  • the mass proportion of clinker in the hydraulic binder may be from 0% to 100% relative to the weight of the binder, preferably from 5% to 95%, more preferably from 30% to 85%.
  • the invention is particularly advantageous for hydraulic compositions having a low clinker content.
  • a low clinker ratio means a clinker mass content in the hydraulic binder less than 85%.
  • the reduced amount of clinker is usually compensated in the hydraulic binder by mineral additions, such as a limestone filler described below.
  • Mineral additions are generally materials that can be used as partial or total substitution for clinker.
  • the mineral additions suitable for the hydraulic binder according to the invention can be chosen from slags (for example as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.2), natural or artificial pozzolans (for example such as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.3), fly ash (for example as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.4), calcined schists (For example as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.5), mineral additions based on calcium carbonate, for example limestone (for example as defined in standard NF EN 197 1 February 2001, paragraph 5.2.6), silica fumes (for example as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.7), metakaolins, biomass ash (for example ashes of rice husks) and mixtures thereof.
  • slags for example as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.2
  • natural or artificial pozzolans for example such as defined in standard NF EN
  • the mineral additions used according to the invention may also be ash from the combustion of plants, such as for example the ashes from the combustion of rice balls.
  • the mineral additions used according to the invention may also be zeolites.
  • Flying ash is usually a powdery particle in the flue gases of coal-fired power plants. It is usually recovered by electrostatic or mechanical precipitation.
  • the chemical composition of a fly ash depends mainly on the chemical composition of the burned coal and the process used in the thermal power plant from which it originated. It is the same for its mineralogical composition.
  • the fly ash used according to the invention may be of siliceous or calcic nature.
  • the fly ash used according to the present invention is chosen from those as described in European Standard NF EN 197-1 of February 2001.
  • Slags are generally obtained by rapidly cooling the molten slag from the smelting of iron ore in a blast furnace.
  • the slags used according to the present invention may be chosen from granulated blast furnace slags according to the European Standard NF EN 197-1 of February 2001, paragraph 5.2.2.
  • the silica fumes used according to the present invention may be a material obtained by the reduction of high purity quartz by charcoal in electric arc furnaces used for the production of silicon and ferrosilicon alloys.
  • the silica fumes are generally formed of spherical particles comprising at least 85% by mass of amorphous silica.
  • the silica fumes used according to the present invention are chosen from silica fumes according to the European standard NF EN 197-1 of February 2001, paragraph 5.2.7.
  • the pozzolanic materials used according to the present invention may be natural siliceous or silico-aluminous substances, or a combination thereof.
  • Pozzolanic materials include natural pozzolans, which are generally materials of volcanic origin or sedimentary rocks, and calcined natural pozzolans, which are materials of volcanic origin, clays, shales or rocks. sedimentary, thermally activated.
  • the pozzolanic materials used according to the invention may be chosen from pumice, tuffs, slag or mixtures thereof.
  • the pozzolanic materials used according to the present invention are chosen from pozzolanic materials according to European Standard NF EN 197-1 of February 2001, section 5.2.3.
  • the mineral additives used according to the invention are materials containing calcium carbonate, for example limestone (also called limestone filler).
  • the calcined clays used according to the present invention can result from the calcination of a clay, kaolinite, associated with different minerals (phyllosilicates, quartz, iron oxides) in varying proportions depending on the deposits. They can be obtained either by grinding calcination or by grinding calcination in production units with rotary kilns, trays or so-called “flash” calcination, for example. They are essentially composed of amorphous alumina silicate particles.
  • the calcined clays used according to the present invention may be chosen from metakaolins according to the preliminary draft standard PR NF P 18-513 of December 2011.
  • the hydraulic binder of the invention may further comprise calcium sulphate.
  • the calcium sulphate used includes gypsum (calcium sulfate dihydrate,
  • CaSO 4 .2H 2 O the hemihydrate (CaSO 4 .1 / 2H 2 O), the anhydrite (anhydrous calcium sulfate, CaSO 4 ) or a mixture thereof.
  • Gypsum and anhydrite exist in their natural state. It is also possible to use a calcium sulphate which is a by-product of certain industrial processes.
  • the hydraulic binder of the invention comprises from 3% to 28% by weight of calcium sulphate relative to the weight of clinker.
  • a high content of calcium sulphate is generally adopted for aluminous and sulphoaluminous cements.
  • the chemical nature (gypsum, hemihydrate or anhydrite) and the calcium sulphate dosage are advantageously adjusted depending on the cement to prevent swelling of the hydrates.
  • the hydraulic binder of the invention comprises from 1% to 8%, preferably from 2% to 5% by mass of calcium sulphate relative to the mass of clinker.
  • a binder according to the invention is generally obtained by co-grinding a clinker and calcium sulphate.
  • Metallic elements
  • a hydraulic composition in the cured state according to the invention may comprise metal elements, such as reinforcements, in particular reinforced concrete reinforcements according to European Standard NF EN 1992-1-1 of October 2005.
  • the frames can be in the form of bars, welded mesh or assembly of bars, reinforcement.
  • the junctions of the bars may be provided by overlapping, splicing, soldering, ligation, crimping or any other means.
  • the metal elements are drawn steel fibers completely or partially replacing ordinary metal reinforcements in certain applications (pavements, shotcrete or repair concrete).
  • a hydraulic composition according to the invention may comprise aggregates.
  • the aggregates optionally used in the composition according to the invention include sand (whose particles generally have a maximum size (Dmax) less than or equal to 4 mm), and possibly chippings (whose particles generally have a minimum size (Dmin) greater than 4 mm and preferably a Dmax less than or equal to 20 mm).
  • the aggregates used in the composition according to the invention are generally in accordance with European Standard NF EN 12620 of August 2003, and are of natural or artificial origin. Aggregates can also be wood.
  • a hydraulic composition according to the invention may comprise conventional adjuvants subject to their compatibility with the crosslinked polyacrylamide (s) required according to the invention.
  • the hydraulic composition according to the invention comprises at least one adjuvant for hydraulic composition: an accelerator, an air-entraining agent, a viscosifying agent, a retarder, an inerting clays, an antifoaming agent, a plasticizer and / or a superplasticizer.
  • the hydraulic composition according to the invention comprises at least one antifoam agent avoiding the entrainment of air in the composition.
  • Inerting clays are compounds that reduce or prevent the harmful effects of clays on the properties of hydraulic binders. Inerting clays include those described in WO 2006/032785 and WO 2006/032786.
  • a water reducer is defined as an adjuvant which typically reduces the amount of mixing water of a concrete for a given workability from typically 10% to 15%.
  • Water reducers include, for example, lignosulfonates, hydroxycarboxylic acids, carbohydrates and other specialized organic compounds, for example glycerol, polyvinyl alcohol, sodium alumino-methyl-siliconate, sulfanilic acid and casein.
  • Superplasticizers belong to a new class of water reducers, chemically different from normal water reducers and able to reduce water amounts by about 30%.
  • Superplasticizers were broadly classified into four groups: sulfonated condensates of naphthalene formaldehyde (SNF) (usually a sodium salt); sulphonated condensates of melamine formaldehyde (SMF); modified lignosulfonates (MLS); And the others. More recent superplasticizers include polycarboxylic compounds such as polycarboxylates, for example polyacrylates.
  • SNF naphthalene formaldehyde
  • SMF sulphonated condensates of melamine formaldehyde
  • MLS modified lignosulfonates
  • More recent superplasticizers include polycarboxylic compounds such as polycarboxylates, for example polyacrylates.
  • a superplasticizer is preferably a new generation superplasticizer, for example a copolymer containing a polyethylene glycol as a grafted chain and carboxylic functions in the main chain as a polycarboxylic ether.
  • Sodium polycarboxylate polysulfonates and sodium polyacrylates can also be used. Phosphonic acid derivatives, sodium polycarboxylate polysulfonates and sodium polyacrylates may also be used.
  • the required amount of superplasticizer usually depends on the reactivity of the cement. The lower the reactivity, the lower the required amount of superplasticizer. To reduce the total amount of alkaline salts, the superplasticizer can be used as a calcium salt rather than as a sodium salt.
  • Antifoam agents also include silicones in the form of a solution of. solid or preferably in the form of resin, oil or emulsion, preferably in water. More particularly suitable are silicones comprising (RSiOo, 5) and (R 2 SiO) groups.
  • the R radicals which may be the same or different, are preferably a hydrogen atom or an alkyl group of 1 to 8 carbon atoms, the methyl group being preferred.
  • the number of patterns is preferably from 30 to 120.
  • the amount of such an agent in the final cement is generally at most 5 parts by weight relative to the cement.
  • a hydraulic composition according to the invention comprises:
  • a hydraulic binder comprising a Portland clinker, calcium sulphate, optionally a limestone filler or another mineral addition, the clinker mass proportion in the binder being from 30% to 85%, at least one crosslinked polyacrylamide in the form of a powder of particles having a mean size of from 300 ⁇ to 2,000 ⁇ , said crosslinked polyacrylamide having a nitrogen content greater than or equal to 4% by weight relative to the weight of the polyacrylamide, in a weight ratio polyacrylamide (s) cross-linked (s) / binder from 0.01% to 5.0%,
  • the weight ratio water / binder is from 0.4 to 1.2, preferably from 0.3 to 0.7,
  • a granulate such as sand
  • a hydraulic composition according to the invention may be prepared by contacting at least one hydraulic binder, at least one crosslinked polyacrylamide in the form of a powder of particles having an average size of 300 ⁇ to 2,000 ⁇ , said crosslinked polyacrylamide having a nitrogen content greater than or equal to 4% by mass relative to the weight of the polyacrylamide, in a weight ratio of polyacrylamide (s) crosslinked (s) / binder of 0.01% to 5.0%, and of the water.
  • the crosslinked polyacrylamide (s) is (are) used in the form of a powder.
  • the hydraulic binder and the crosslinked polyacrylamide (s) are (are) previously brought into contact in dry form, advantageously in the form of a powder, before the mixture obtained is brought into contact with water.
  • the hydraulic composition according to the invention can be used directly on site in the fresh state and cast in a formwork adapted to the intended application, or used in prefabrication plant.
  • the mixing of the hydraulic composition can be carried out according to methods known to those skilled in the art.
  • a hydraulic composition according to the present invention can be shaped to produce, after hydration and hardening, a shaped object for the field of construction.
  • Objects shaped for the field of construction include, for example, a floor, a screed, a foundation, a wall, a partition, a ceiling, a beam, a worktop, a pillar, a bridge stack, a cinder block, a pipe, a pole, a staircase, a panel, a cornice, a mold, a road element (for example a curb), or a covering (for example road or wall).
  • Mortar specimens were prepared from a hydraulic composition comprising a low clinker hydraulic binder (35% substituted by a calcareous filler).
  • the water / binder ratio is equal to 0.55 and the TiBP (defoaming agent) dosage is 0.09% / binder.
  • Table 1 The composition of the specimens is shown in Table 1 and the characteristics of the cement and sand are shown in Tables 2 and 3. Table 1
  • the sand was put into the bowl of a Perrier type 32 mixer with prewetting water. Mixing started and was maintained at low speed for 1 minute.
  • the kneading was then stopped for 4 minutes.
  • the hydraulic binder (cement + filter) and the cross-linked polyacrylamide powder were added and mixing was resumed at low speed for 1 minute.
  • the mixing water comprising the adjuvants (antifoam and plasticizer), was then added in 30 seconds while mixing at low speed.
  • the mixture was kneaded at high speed for 1 minute to obtain a mortar.
  • the mortar was then poured into polystyrene molds measuring 4 cm x 4 cm x 16 cm (without vibration) to obtain 6 concrete specimens (demolded after 24 h at 20 ° C at 100% relative humidity). ).
  • the mortar specimens were then placed under accelerated carbonation conditions. After 6 days of curing in a wet cabinet at 100% relative humidity and 20 ° C., the test pieces were placed in a carbonation box (rectangular HDPE tank, with a capacity of 576 liters, equipped with a tight-fitting lid). whose atmosphere has been enriched with CO 2 (10% +/- 0.5% C0 2 in the air volume of the chamber), 20 ° C +/- 1 ° C and 65% +/- 5% relative humidity.
  • a carbonation box rectangular HDPE tank, with a capacity of 576 liters, equipped with a tight-fitting lid.
  • the temperature regulation was ensured by the fact that the box was placed in a laboratory regulated at 20 +/- 1 ° C.
  • the relative humidity was regulated by a tray filled with ammonium nitrate salt saturated with water, this tray being positioned at the bottom of the box, over the entire available surface.
  • the box was connected to a network fed by bottles filled with a mixture of 50% CO 2 /50% nitrogen under pressure.
  • An expansion unit has enabled the mixture to be delivered at 1 bar of relative pressure in the network.
  • the introduction of the gas was managed automatically by a CO 2 gas analyzer which continuously analyzed the atmosphere of the box (ABISS wall scanner, model LMP 320, supplied by the company PBI Datasensor). At each introduction of gas, another electro valve was opened to evacuate excess gas to a crawl space outside the laboratory, this to prevent overpressure in the box.
  • a fan operated continuously to have a homogeneous distribution of CO 2 gas in the atmosphere of the box.
  • the specimens were taken out of the carbonation box and split with a hydraulic cutter to determine the depth of carbonation.
  • Resistance to carbonation was estimated by measuring the carbonation depth of the specimens. This depth was measured after different periods of exposure of the specimens in the box enriched in gaseous CO 2 .
  • the material is said to be carbonated when its pH is less than or equal to 9. This is visualized by spraying a solution of 0.5% phenolphthalein diluted in a mixture composed of 50% demineralised water and 50% ethanol. Phenolphthalein is a colored indicator that changes to purple pink when the pH is above 9 and remains colorless when the pH is below 9. The carbonated concrete zones are therefore those that remain colorless after spraying the phenolphthalein suspension.
  • the depths of carbonate concrete and mortar were measured in several zones. The arithmetic mean of the values obtained was calculated. Results
  • crosslinked polyacrylamides led to significantly reduced carbonation depths compared to the crosslinked polyacrylamide-free sample.

Abstract

The present invention relates to the use of at least one cross-linked polyacrylamide in the form of a powder of particles having an average size of between 300 µm and 2000 µm. Said cross-linked polyacrylamide has a nitrogen content greater than or equal to 4 wt% relative to the weight of said polyacrylamide, and is combined with at least one hydraulic binder in a hydraulic composition so as to reduce and/or prevent carbonation in said hydraulic composition. Said cross-linked polyacrylamide(s) is/are present in said hydraulic composition in a weight ratio of cross-linked polyacrylamide(s)/binder of between 0.01% to 5.0%.

Description

UTILISATION DE POLYACRYLAMIDE DANS UNE COMPOSITION  USE OF POLYACRYLAMIDE IN A COMPOSITION
HYDRAULIQUE POUR UNE RESISTANCE A LA CARBONATATION HYDRAULICS FOR CARBONATION RESISTANCE
AMELIOREE IMPROVED
La présente invention se rapporte au domaine des matériaux de construction, et plus particulièrement à l'utilisation d'un additif dans une composition hydraulique pour en améliorer la résistance à la carbonatation et ainsi améliorer la durabilité de l'ouvrage résultant du durcissement de la composition hydraulique. The present invention relates to the field of construction materials, and more particularly to the use of an additive in a hydraulic composition to improve the resistance to carbonation and thus improve the durability of the structure resulting from the hardening of the composition hydraulic.
La durabilité des ouvrages en béton ou en mortier obtenus par durcissement d'une composition hydraulique est une préoccupation majeure. En effet, un ouvrage doit résister au cours du temps aux diverses agressions ou sollicitations (physiques, mécaniques, chimiques, ...), c'est-à-dire aux charges auxquelles il est soumis, ainsi qu'au vent, à la pluie, au froid, à la chaleur ou au milieu ambiant. Or l'exposition à l'atmosphère ambiante peut provoquer la carbonatation du matériau issu du durcissement d'une composition hydraulique. En effet, la quantité d'eau introduite dans la composition hydraulique à l'état frais est souvent supérieure à la quantité stœchiométrique, ce qui amène à un milieu poreux dont les pores sont d'abord remplis d'eau. Lorsque le matériau cimentaire sèche, il se désature en eau et les pores se remplissent partiellement d'air. Le CO2 atmosphérique diffuse ainsi dans la composition hydraulique hydratée par sa porosité et vient réagir avec les hydrates du ciment, en particulier avec la portlandite, pour former du carbonate de calcium. Il en résulte une baisse du pH, qui passe généralement d'une valeur de 13 dans la zone non carbonatée à une valeur généralement inférieure à 9 dans la zone carbonatée. Le pH de la zone dégradée de la composition hydraulique durcie baisse et initie la corrosion des aciers en milieu humide et en présence d'oxygène. The durability of concrete or mortar structures obtained by hardening a hydraulic composition is a major concern. Indeed, a work must withstand over time to the various aggressions or solicitations (physical, mechanical, chemical, ...), that is to say to the loads to which it is subjected, as well as wind, to the rain, cold, heat or environment. However exposure to the ambient atmosphere can cause the carbonation of the material resulting from the hardening of a hydraulic composition. Indeed, the amount of water introduced into the hydraulic composition in the fresh state is often greater than the stoichiometric amount, which leads to a porous medium whose pores are first filled with water. When the cementitious material dries, it becomes desaturated in water and the pores partially fill with air. The atmospheric CO 2 thus diffuses into the hydraulic composition hydrated by its porosity and reacts with the hydrates of the cement, in particular with portlandite, to form calcium carbonate. This results in a drop in pH, which generally goes from a value of 13 in the non-carbonated zone to a value generally less than 9 in the carbonated zone. The pH of the degraded zone of the hardened hydraulic composition decreases and initiates the corrosion of the steels in a humid medium and in the presence of oxygen.
En cas de corrosion, la rouille se développe autour des barres d'acier et fait éclater la composition d'enrobage, ce qui pose problème. Le béton issu de la composition hydraulique s'en trouve endommagée et la corrosion est d'autant plus accélérée que les armatures métalliques sont mises à nues.  In case of corrosion, the rust develops around the steel bars and burst the coating composition, which is a problem. The concrete resulting from the hydraulic composition is damaged and the corrosion is all the more accelerated as the metal frames are exposed.
La carbonatation est notamment un problème majeur pour les compositions hydrauliques à faible taux de clinker. En effet, lors du durcissement, ces compositions hydrauliques sont très sensibles à la carbonatation du fait de leur faible taux de Portlandite (phase créée lors de l'hydratation d'un clinker, notamment Portland), cette phase jouant un rôle tampon dans la progression de la carbonatation. Afin de répondre aux exigences des utilisateurs, il est devenu nécessaire de trouver un moyen pour réduire ou prévenir la carbonatation, et ainsi la corrosion d'éléments métalliques quand ils sont présents, dans les compositions hydrauliques à l'état durci, en particulier les compositions hydrauliques ayant un faible taux de clinker et comprenant des additions minérales. Carbonation is a major problem for hydraulic compositions with low clinker content. Indeed, during hardening, these hydraulic compositions are very sensitive to carbonation because of their low rate of Portlandite (phase created during the hydration of a clinker, especially Portland), this phase playing a buffer role in the progression carbonation. In order to meet the requirements of the users, it has become necessary to find a means for reducing or preventing carbonation, and thus the corrosion of metal elements when they are present, in the hydraulic compositions in the cured state, in particular the compositions hydraulic systems with low clinker content and mineral additions.
Aussi le problème que se propose de résoudre l'invention est de fournir un moyen pour réduire ou prévenir la carbonatation, et ainsi la corrosion d'éléments métalliques quand ils sont présents, dans les compositions hydrauliques à l'état durci, en particulier les compositions hydrauliques ayant un faible taux de clinker et comprenant des additions minérales. Il est à noter que la présente invention cherche à réduire ou prévenir la carbonatation à un degré d'avancement de l'hydratation donné, qui est caractérisé par une même résistance mécanique en compression (iso-résistance). Sans être lié par la théorie, il semblerait en effet que la carbonatation soit fortement liée à l'avancement de l'hydratation. Plus précisément, la présente invention se rapporte à l'utilisation d'au moins un polyacrylamide réticulé, sous la forme d'une poudre de particules ayant une taille moyenne comprise de 300 μηι à 2 000 μηι, ledit polyacrylamide réticulé ayant un taux d'azote supérieur ou égal à 4 % en masse par rapport à la masse dudit polyacrylamide, en association avec au moins un liant hydraulique dans une composition hydraulique, pour réduire et/ou prévenir la carbonatation au sein de ladite composition hydraulique, ledit ou lesdits polyacrylamide(s) réticulé(s) étant présent(s) dans ladite composition hydraulique selon un rapport pondéral polyacrylamide(s) réticulé(s)/liant compris de 0,01 % à 5,0 %.  Also the problem to be solved by the invention is to provide a means for reducing or preventing carbonation, and thus the corrosion of metal elements when present, in the hydraulic compositions in the cured state, in particular the compositions hydraulic systems with low clinker content and mineral additions. It should be noted that the present invention seeks to reduce or prevent carbonation at a given stage of the hydration, which is characterized by the same mechanical resistance in compression (iso-resistance). Without being bound by theory, it would seem that carbonation is strongly linked to the progress of hydration. More specifically, the present invention relates to the use of at least one crosslinked polyacrylamide, in the form of a powder of particles having an average size of 300 μηι to 2,000 μηι, said crosslinked polyacrylamide having a degree of nitrogen greater than or equal to 4% by weight relative to the mass of said polyacrylamide, in combination with at least one hydraulic binder in a hydraulic composition, for reducing and / or preventing carbonation within said hydraulic composition, said polyacrylamide (s) ( s) crosslinked being present in said hydraulic composition in a weight ratio polyacrylamide (s) crosslinked (s) / binder of 0.01% to 5.0%.
En particulier, la présente invention se rapporte à l'utilisation d'au moins un polyacrylamide réticulé, sous la forme d'une poudre de particules ayant une taille moyenne comprise de 300 μηι à 2 000 μηι, ledit polyacrylamide réticulé ayant un taux d'azote supérieur ou égal à 4 % en masse par rapport à la masse dudit polyacrylamide, en association avec au moins un liant hydraulique dans une composition hydraulique à l'état frais, ledit ou lesdits polyacrylamide(s) réticulé(s) étant présent(s) dans ladite composition hydraulique selon un rapport pondéral polyacrylamide(s) réticulé(s)/liant compris de 0,01 % à 5,0 %, pour réduire et/ou prévenir la carbonatation au sein de ladite composition hydraulique à l'état durci. De manière inattendue, les inventeurs ont mis en évidence que l'utilisation d'un (ou plusieurs) polyacrylamide réticulé ajouté directement dans la masse d'une composition hydraulique permet de réduire et/ou prévenir la carbonatation de la composition à l'état durci, et ainsi d'améliorer la durabilité de la composition hydraulique et de diminuer la corrosion des armatures métalliques. In particular, the present invention relates to the use of at least one crosslinked polyacrylamide, in the form of a powder of particles having a mean size of from 300 μηι to 2,000 μηι, said crosslinked polyacrylamide having a degree of nitrogen greater than or equal to 4% by weight relative to the mass of said polyacrylamide, in combination with at least one hydraulic binder in a fresh hydraulic composition, said at least one crosslinked polyacrylamide (s) being present (s); ) in said hydraulic composition in a weight ratio of polyacrylamide (s) crosslinked (s) / binder of 0.01% to 5.0%, for reducing and / or preventing carbonation within said hydraulic composition in the cured state . Unexpectedly, the inventors have demonstrated that the use of one (or more) crosslinked polyacrylamide added directly to the mass of a hydraulic composition makes it possible to reduce and / or prevent the carbonation of the composition in the cured state. and thus to improve the durability of the hydraulic composition and to reduce the corrosion of the metal reinforcements.
La présente invention permet d'accéder à une composition hydraulique à durabilité améliorée qui a une ou plusieurs des caractéristiques suivantes :  The present invention provides access to an improved durability hydraulic composition that has one or more of the following characteristics:
- la composition hydraulique présente une résistance améliorée à la carbonatation ; the hydraulic composition has improved resistance to carbonation;
- les armatures métalliques présentes dans la composition hydraulique ne sont pas ou peu corrodées ; the metal reinforcements present in the hydraulic composition are not or only slightly corroded;
- la corrosion des armatures métalliques peut être retardée lorsque celle-ci se produit ; - the corrosion of metal reinforcements can be delayed when this occurs;
- l'enrobage (tel que défini dans la norme NF EN 1992-1-1 d'octobre 2005, paragraphe 4.4.1.1) des armatures devient moins critique et le positionnement des armatures dans l'épaisseur de la composition hydraulique est facilité ; the coating (as defined in standard NF EN 1992-1-1 of October 2005, paragraph 4.4.1.1) of the reinforcements becomes less critical and the positioning of the reinforcements in the thickness of the hydraulic composition is facilitated;
- la composition hydraulique peut comprendre un taux réduit de clinker, sans que cela ne favorise la corrosion des armatures métalliques ;  the hydraulic composition may comprise a reduced rate of clinker, without this promoting the corrosion of the metal reinforcements;
- la composition hydraulique permet de former une barrière à d'autres gaz que le CO2 (par exemple radon, chlore, et oxygène), ainsi qu'une barrière aux liquides. the hydraulic composition makes it possible to form a barrier to gases other than CO 2 (for example radon, chlorine, and oxygen), as well as a liquid barrier.
La présente invention trouve particulièrement à s'appliquer pour les bétons armés, en particulier les bétons armés à base de composition hydraulique ayant un faible taux de clinker.  The present invention is particularly applicable to reinforced concretes, in particular reinforced concrete based on hydraulic composition having a low level of clinker.
Conventionnellement, on entend par « liant hydraulique » un matériau sec qui prend et durcit par hydratation. La prise est le passage de l'état liquide ou pâteux à l'état solide. La prise est suivie ou accompagnée d'un phénomène de durcissement pendant lequel le matériau acquiert des propriétés mécaniques. Le durcissement a généralement lieu après la fin de la prise, particulièrement pour les ciments. Conventionally, the term "hydraulic binder" means a dry material that takes and hardens by hydration. The setting is the transition from liquid or pasty state to solid state. The setting is followed or accompanied by a curing phenomenon during which the material acquires mechanical properties. Hardening usually occurs after the end of setting, especially for cements.
Un liant hydraulique comprend généralement un clinker, du sulfate de calcium, et une ou plusieurs addition(s) minérale(s), notamment tels que détaillés ci-après.  A hydraulic binder generally comprises a clinker, calcium sulfate, and one or more mineral additions, in particular as detailed below.
Une composition hydraulique selon l'invention comprend de préférence en outre de l'eau. A hydraulic composition according to the invention preferably further comprises water.
Conventionnellement, on entend par « composition hydraulique » une composition comprenant un liant hydraulique, de l'eau, éventuellement à l'état durci des éléments métalliques, éventuellement des granulats et éventuellement des adjuvants. De préférence, la composition hydraulique de l'invention est un béton, plus particulièrement un béton armé. Conventionally, the term "hydraulic composition" means a composition comprising a hydraulic binder, water, possibly in the hardened state of the elements. metal, possibly aggregates and possibly adjuvants. Preferably, the hydraulic composition of the invention is a concrete, more particularly an reinforced concrete.
La quantité d'eau est telle que le rapport massique eau/liant est de préférence de 0,4 à 1,2 et préférentiellement de 0,4 à 0,7.  The amount of water is such that the water / binder mass ratio is preferably from 0.4 to 1.2 and preferably from 0.4 to 0.7.
Une composition hydraulique selon l'invention inclut à la fois les compositions à l'état frais, par exemple un coulis de ciment, et à l'état durci, par exemple un mortier ou un béton. L'homme du métier comprend que la composition hydraulique à l'état frais comprend de l'eau servant à l'hydratation du liant, tandis que la composition hydraulique à l'état durci est obtenue après hydratation pour donner du béton ou du mortier.  A hydraulic composition according to the invention includes both the compositions in the fresh state, for example a cement slurry, and in the cured state, for example a mortar or a concrete. Those skilled in the art understand that the fresh hydraulic composition comprises water for hydration of the binder, while the cured hydraulic composition is obtained after hydration to give concrete or mortar.
Polyacrylamides réticulés Crosslinked polyacrylamides
La composition hydraulique selon l'invention comprend au moins un polyacrylamide réticulé.  The hydraulic composition according to the invention comprises at least one crosslinked polyacrylamide.
Plus précisément, il s'agit d'un polyacrylamide réticulé non hydrosoluble dit superabsorbant.  More specifically, it is a crosslinked non-water soluble polyacrylamide said superabsorbent.
Cette propriété « superabsorbant » qualifie l'aptitude des polyacrylamides à absorber de l'eau. Ces polymères superabsorbants ont déjà été mis en œuvre dans de nombreux domaines d'application pour profiter de ces capacités de gonflement.  This "superabsorbent" property describes the ability of polyacrylamides to absorb water. These superabsorbent polymers have already been implemented in many fields of application to take advantage of these swelling capacities.
Les polyacrylamides réticulés selon l'invention sont capables de gonfler dans une composition hydraulique en absorbant de l'eau.  The crosslinked polyacrylamides according to the invention are capable of swelling in a hydraulic composition by absorbing water.
Comme il ressort clairement des exemples décrits ci-après, la présence d'un ou plusieurs polyacrylamide(s) réticulé(s) dans une composition hydraulique s'avère tout particulièrement bénéfique pour diminuer la vitesse de carbonatation de ladite composition.  As is clear from the examples described below, the presence of one or more crosslinked polyacrylamide (s) in a hydraulic composition is particularly beneficial to reduce the carbonation rate of said composition.
Ainsi, la composition hydraulique de l'invention, qui incorpore au moins un polyacrylamide réticulé, présente une résistance à la carbonatation supérieure à une composition hydraulique de référence dépourvue de polyacrylamide réticulé, ce qui permet d'améliorer la durabilité de ladite composition hydraulique et de diminuer la corrosion d'éventuelles armatures métalliques. Dans le cadre de la présente invention, on entend couvrir par le terme Thus, the hydraulic composition of the invention, which incorporates at least one crosslinked polyacrylamide, has a greater resistance to carbonation than a reference hydraulic composition free of crosslinked polyacrylamide, which makes it possible to improve the durability of said hydraulic composition and of reduce the corrosion of any metal reinforcements. In the context of the present invention, it is intended to cover by the term
« polyacrylamide » un polymère formé uniquement de motifs monomériques acrylamide (H2C=CH-C(0)-NH2), dit encore homopolymère, et également un polymère comprenant une ou plusieurs autres entités monomériques différentes des unités monomères acrylamide, dit encore copolymère. Selon un mode de réalisation, un polyacrylamide convenant à l'invention peut comprendre des motifs amide et motifs anioniques, cationiques ou non ioniques, différents des motifs amide. "Polyacrylamide" a polymer formed solely of monomeric units acrylamide (H 2 C = CH-C (O) -NH 2 ), also called homopolymer, and also a polymer comprising one or more other monomeric entities different from acrylamide monomer units, also known as copolymer. According to one embodiment, a polyacrylamide that is suitable for the invention may comprise amide units and anionic, cationic or nonionic units, different from the amide units.
Ce type de polyacrylamide peut être obtenu par polymérisation d'un mélange de monomères comprenant des unités monomères acrylamide et des comonomères anioniques, cationiques ou non ioniques, différents des monomères acrylamide.  This type of polyacrylamide can be obtained by polymerization of a monomer mixture comprising acrylamide monomer units and anionic, cationic or nonionic comonomers, different from the acrylamide monomers.
Les unités monomères non ioniques peuvent être par exemple choisies parmi l'acétate de vinyle et l'alcool vinylique.  The nonionic monomer units may for example be chosen from vinyl acetate and vinyl alcohol.
Les unités monomères anioniques peuvent être par exemple choisies dans le groupe constitué par les sels alcalins ou d'ammonium d'acide méthacrylique, d'acide 2-acrylamido- 2-méthylpropanesulfonique, ou d'acide maléique.  The anionic monomer units may for example be selected from the group consisting of alkali or ammonium salts of methacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, or maleic acid.
Les unités monomères cationiques peuvent être par exemple choisies dans le groupe constitué par le chlorure de (méth)acrylamidoéthyltriméthylammonium et le chlorure de (méth)acrylamido propyltriméthylammonium.  The cationic monomer units can be, for example, chosen from the group consisting of (meth) acrylamidoethyltrimethylammonium chloride and (meth) acrylamidopropyltrimethylammonium chloride.
Selon une variante, un polyacrylamide convenant à l'invention peut comprendre des motifs amide et des motifs acide carboxylique et/ou carboxylate. Par « carboxylate », on entend notamment carboxylate de métal alcalin, particulièrement de sodium ou de potassium, ou carboxylate d'ammonium. According to one variant, a polyacrylamide that is suitable for the invention may comprise amide units and carboxylic acid and / or carboxylate units. By "carboxylate" is meant in particular alkali metal carboxylate, particularly sodium or potassium, or ammonium carboxylate.
Ces motifs acide carboxylique ou carboxylate peuvent être générés à partir des unités monomériques acrylamide par hydrolyse. Les polyacrylamides sont dans ce cas obtenus par polymérisation de monomères acrylamide puis par hydrolyse.  These carboxylic acid or carboxylate units can be generated from the acrylamide monomeric units by hydrolysis. In this case, the polyacrylamides are obtained by polymerization of acrylamide monomers and then by hydrolysis.
Ces motifs acide carboxylique ou carboxylate peuvent aussi provenir d'unités monomériques acide acrylique ou acrylate. Les polyacrylamides sont dans ce cas obtenus par copolymérisation de monomères acrylamide et de monomères acide acrylique et/ou acrylate.  These carboxylic acid or carboxylate units can also come from monomeric units acrylic acid or acrylate. In this case, the polyacrylamides are obtained by copolymerization of acrylamide monomers and acrylic acid and / or acrylate monomers.
De préférence, un polyacrylamide comprend des motifs amide et des motifs acide carboxylique et/ou carboxylate selon un rapport molaire amide/(acrylique et/ou acrylate) compris de 0,20 à 9,0.  Preferably, a polyacrylamide comprises amide units and carboxylic acid and / or carboxylate units in an amide / (acrylic and / or acrylate) molar ratio of from 0.20 to 9.0.
Dans le cadre de la présente invention, on entend par « polyacrylamide réticulé », un homopolymère ou copolymère d'acrylamide tel que décrit ci-dessus, obtenu par polymérisation d'un mélange comprenant au moins un monomère acrylamide et au moins un agent réticulant. La présence d'un agent reticulant dans le mélange permet de relier les chaînes polyacrylamide les unes aux autres et de créer un réseau tridimensionnel de chaînes polyacrylamide. Un polyacrylamide réticulé consiste ainsi essentiellement en des segments linéaires, réticulés entre eux, dont certains atomes de carbone sont porteurs d'un groupement amide (éventuellement hydrolysé), contribuant au caractère hydrophile du polyacrylamide réticulé. In the context of the present invention, the term "crosslinked polyacrylamide", a homopolymer or copolymer of acrylamide as described above, obtained by polymerization of a mixture comprising at least one acrylamide monomer and at least one crosslinking agent. The presence of a crosslinking agent in the mixture makes it possible to connect the polyacrylamide chains to one another and to create a three-dimensional network of polyacrylamide chains. A crosslinked polyacrylamide thus consists essentially of linear segments, crosslinked with each other, some of whose carbon atoms carry an amide group (optionally hydrolysed), contributing to the hydrophilic nature of the crosslinked polyacrylamide.
Le taux de réticulation d'un polyacrylamide réticulé augmente avec la proportion d'agent réticulant dans le mélange de monomères. Les polyacrylamides réticulés conformes à l'invention sont de préférence obtenus à partir de mélanges de monomères comprenant de 0,1 % à 20 %, préférentiellement de 1 % à 10 %, avantageusement de 2 % à 5 % d'agent(s) réticulant(s) en poids par rapport au poids total du mélange de monomères.  The degree of crosslinking of a crosslinked polyacrylamide increases with the proportion of crosslinking agent in the monomer mixture. The crosslinked polyacrylamides according to the invention are preferably obtained from monomer mixtures comprising from 0.1% to 20%, preferably from 1% to 10%, advantageously from 2% to 5% of crosslinking agent (s). (s) by weight relative to the total weight of the monomer mixture.
Au contraire des polyacrylamides linéaires (non réticulés), les polyacrylamides réticulés sont des gels hydrophiles mais non hydrosolubles, et ce caractère hydrophile se traduit par des propriétés superabsorbantes avantageusement mises en œuvre dans le cadre de la présente invention.  In contrast to linear (non-crosslinked) polyacrylamides, the crosslinked polyacrylamides are hydrophilic but non-water-soluble gels, and this hydrophilic nature results in superabsorbent properties advantageously used in the context of the present invention.
Plus particulièrement, à titre de polyacrylamide réticulé adapté à la mise en œuvre de l'invention, on peut citer les copolymères acrylamide/acrylate de métal alcalin, comme par exemple les copolymères acrylamide/acrylate de sodium ou de potassium, notamment le polyacrylamide Aquasorb 3005 Max de la société SNF.  More particularly, as crosslinked polyacrylamide adapted to the implementation of the invention, mention may be made of acrylamide / alkali metal acrylate copolymers, such as, for example, acrylamide / sodium or potassium acrylate copolymers, in particular polyacrylamide Aquasorb 3005. Max from the SNF company.
Le taux d'azote d'un polyacrylamide peut être variable et est généralement supérieur ou égal à 4 % en masse par rapport à la masse dudit polyacrylamide. The nitrogen content of a polyacrylamide may be variable and is generally greater than or equal to 4% by weight relative to the mass of said polyacrylamide.
Le dosage en azote d'un polyacrylamide peut être mesuré par un NOT-Mètre avec une chambre de combustion du solide. Le polyacrylamide est d'abord oxydé pour former des oxydes d'azote. Ces oxydes sont ensuite réduits en NO. Ce NO est envoyé dans une chambre de réaction contenant de l'ozone O3 en excès ; il y a alors émission de lumière proportionnelle à la concentration en monoxyde d'azote. La lumière émise est mesurée par un photomultiplicateur puis un signal, observable sous forme d'un pic, est obtenu.  The nitrogen dosage of a polyacrylamide can be measured by a NOT-meter with a solid combustion chamber. Polyacrylamide is first oxidized to form nitrogen oxides. These oxides are then reduced to NO. This NO is sent to a reaction chamber containing ozone O3 in excess; there is then light emission proportional to the concentration of nitric oxide. The emitted light is measured by a photomultiplier and a signal, observable in the form of a peak, is obtained.
Le ou les polyacrylamide(s) réticulé(s) apte(s) à la mise en œuvre de l'invention présentent un taux d'azote supérieur ou égal à 4 % en masse par rapport à la masse dudit polyacrylamide.  The crosslinked polyacrylamide (s) suitable for the implementation of the invention have a nitrogen content greater than or equal to 4% by weight relative to the weight of said polyacrylamide.
De préférence, le taux d'azote est compris de 4 % à 18 %, avantageusement compris de 9 % à 15 %, en masse par rapport à la masse dudit polyacrylamide. Le ou les polyacrylamide(s) réticulé(s) de l'invention se présente(nt) sous la forme d'une poudre de particules de polymère, ayant une taille moyenne comprise de 300 μηι à 2 000 μηι, préférentiellement de 300 μηι à 1 000 μηι, et avantageusement de 350 μηι à 600 μηι. Preferably, the nitrogen content is from 4% to 18%, advantageously from 9% to 15% by weight relative to the weight of said polyacrylamide. The crosslinked polyacrylamide (s) of the invention is (are) in the form of a powder of polymer particles having an average size of from 300 μηι to 2,000 μηι, preferably from 300 μηι to 1000 μηι, and advantageously from 350 μηι to 600 μηι.
La taille des particules de polyacrylamides réticulés est généralement mesurée par tamisage ou par granulométrie laser. On parle alors de taille de particules maximale.  The size of the crosslinked polyacrylamide particles is generally measured by sieving or laser particle size. This is called the maximum particle size.
La production industrielle des particules de polyacrylamide réticulé comprend généralement les étapes suivantes : Industrial production of the crosslinked polyacrylamide particles generally comprises the following steps:
· une étape de copolymérisation d'au moins deux monomères (généralement acide acrylique et acrylamide) en présence d'un agent réticulant.  A copolymerization step of at least two monomers (generally acrylic acid and acrylamide) in the presence of a crosslinking agent.
• une étape de séchage par atomisation pour la polymérisation en émulsion inverse, ou  A spray drying step for the inverse emulsion polymerization, or
• une étape de séchage, broyage et tamisage, pour la polymérisation en masse.  A step of drying, grinding and sieving, for mass polymerization.
La copolymérisation est réalisée en masse ou en émulsion inverse. L'agent réticulant peut être le glyoxal, le 1,1,2,2-éthanetétrol, le Ν,Ν'-méthylène bisacrylamide, le diacrylamide de pipérazine, le Ν,Ν'-bisacrylylcystamine, ou le Ν,Ν'-diallyltartradiamide. Le poids moléculaire moyen en poids (Mw) des polymères obtenus est très élevé (> 10 000 000 g/mol). Les polyacrylamides réticulés conformes à l'invention sont de préférence obtenus par polymérisation en masse selon la méthode décrite ci-dessus.  The copolymerization is carried out in bulk or in inverse emulsion. The crosslinking agent may be glyoxal, 1,1,2,2-ethanetetrol, Ν, Ν'-methylenebisacrylamide, piperazine diacrylamide, Ν, Ν'-bisacrylylcystamine, or Ν, Ν'-diallyltartradiamide. . The weight average molecular weight (Mw) of the polymers obtained is very high (> 10,000,000 g / mol). The crosslinked polyacrylamides according to the invention are preferably obtained by mass polymerization according to the method described above.
Le ou les polyacrylamide(s) réticulé(s) est (sont) présent(s) dans la composition hydraulique selon un rapport massique compris de 0,01 % à 5,0 % par rapport à la masse du liant. The crosslinked polyacrylamide (s) is (are) present in the hydraulic composition in a weight ratio of from 0.01% to 5.0% relative to the weight of the binder.
De préférence, le rapport massique de polyacrylamide(s) réticulé(s) par rapport au liant est compris de 0,05 % à 2,0 %, de 0,05 % à 1,0 %, ou encore de 0,05 % à 0,75 %.  Preferably, the weight ratio of crosslinked polyacrylamide (s) relative to the binder is from 0.05% to 2.0%, from 0.05% to 1.0%, or else from 0.05% at 0.75%.
Préférentiellement, le rapport massique de polyacrylamide(s) réticulé(s) par rapport au liant est compris de 0,1 % à 0,50 %, ou encore de 0,1 % à 0,35 %.  Preferably, the weight ratio of crosslinked polyacrylamide (s) relative to the binder is from 0.1% to 0.50%, or from 0.1% to 0.35%.
La composition de l'invention peut comprendre un mélange de plusieurs polyacrylamide(s) réticulé(s), présentant des taux d'azote différents ou des tailles de particules différentes. Clinker The composition of the invention may comprise a mixture of several crosslinked polyacrylamide (s), having different nitrogen levels or different particle sizes. clinker
Le clinker utilisé selon la présente invention peut être un clinker Portland, un clinker sulfo-alumineux, un clinker alumineux, un clinker bélitique, un clinker sulfo-bélitique et leurs mélanges, de préférence un clinker Portland.  The clinker used according to the present invention may be a Portland clinker, a sulfo-aluminous clinker, an aluminous clinker, a belitic clinker, a sulpho-belitic clinker and mixtures thereof, preferably a Portland clinker.
Un clinker Portland est obtenu par clinkérisation à haute température d'un mélange comprenant notamment du calcaire et de l'argile. Par exemple, un clinker Portland est un clinker tel que défini dans la norme NF EN 197- 1 de février 2001.  A Portland clinker is obtained by high temperature clinkerisation of a mixture comprising in particular limestone and clay. For example, a Portland clinker is a clinker as defined in standard NF EN 197-1 of February 2001.
La proportion massique en clinker dans le liant hydraulique peut-être comprise de 0 % à 100 % par rapport à la masse du liant, de préférence de 5 % à 95 %, plus préférentiellement de 30 % à 85 %.  The mass proportion of clinker in the hydraulic binder may be from 0% to 100% relative to the weight of the binder, preferably from 5% to 95%, more preferably from 30% to 85%.
Comme évoqué précédemment, l'invention est particulièrement intéressante pour des compositions hydrauliques possédant un faible taux en clinker.  As mentioned above, the invention is particularly advantageous for hydraulic compositions having a low clinker content.
Au sens de l'invention, un faible taux de clinker signifie une teneur massique en clinker dans le liant hydraulique inférieure à 85 %.  For the purposes of the invention, a low clinker ratio means a clinker mass content in the hydraulic binder less than 85%.
Ainsi, la quantité réduite en clinker est usuellement compensée dans le liant hydraulique par des additions minérales, comme par exemple un filler calcaire décrit ci-après.  Thus, the reduced amount of clinker is usually compensated in the hydraulic binder by mineral additions, such as a limestone filler described below.
Addition minérale Mineral addition
Les additions minérales sont généralement des matériaux utilisables en substitution partielle ou totale du clinker.  Mineral additions are generally materials that can be used as partial or total substitution for clinker.
Les additions minérales convenant au liant hydraulique selon l'invention peuvent être choisies parmi les laitiers (par exemple tels que définis dans la norme NF EN 197- 1 de février 2001, paragraphe 5.2.2), les pouzzolanes naturelles ou artificielles (par exemple telles que définies dans la norme NF EN 197-1 de février 2001, paragraphe 5.2.3), les cendres volantes (par exemple telles que définies dans la norme NF EN 197-1 de février 2001, paragraphe 5.2.4), les schistes calcinés (par exemple tels que définis dans la norme NF EN 197-1 de février 2001, paragraphe 5.2.5), les additions minérales à base de carbonate de calcium, par exemple le calcaire (par exemple tel que défini dans la norme NF EN 197-1 de février 2001, paragraphe 5.2.6), les fumées de silice (par exemple telles que définies dans la norme NF EN 197-1 de février 2001, paragraphe 5.2.7), les métakaolins, les cendres de biomasses (par exemple les cendres de cosses de riz) et leurs mélanges.  The mineral additions suitable for the hydraulic binder according to the invention can be chosen from slags (for example as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.2), natural or artificial pozzolans (for example such as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.3), fly ash (for example as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.4), calcined schists (For example as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.5), mineral additions based on calcium carbonate, for example limestone (for example as defined in standard NF EN 197 1 February 2001, paragraph 5.2.6), silica fumes (for example as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.7), metakaolins, biomass ash (for example ashes of rice husks) and mixtures thereof.
Les additions minérales utilisées selon l'invention peuvent être également les cendres issues de la combustion de végétaux, comme par exemple les cendres issues de la combustion des balles de riz. Les additions minérales utilisées selon l'invention peuvent être également des zéolithes.The mineral additions used according to the invention may also be ash from the combustion of plants, such as for example the ashes from the combustion of rice balls. The mineral additions used according to the invention may also be zeolites.
Une cendre volante est généralement une particule pulvérulente comprise dans les fumées des centrales thermiques alimentées au charbon. Elle est généralement récupérée par précipitation électrostatique ou mécanique. Flying ash is usually a powdery particle in the flue gases of coal-fired power plants. It is usually recovered by electrostatic or mechanical precipitation.
La composition chimique d'une cendre volante dépend principalement de la composition chimique du charbon brûlé et du procédé utilisé dans la centrale thermique dont elle est issue. Il en est de même pour sa composition minéralogique. Les cendres volantes utilisées selon l'invention peuvent être de nature siliceuse ou calcique.  The chemical composition of a fly ash depends mainly on the chemical composition of the burned coal and the process used in the thermal power plant from which it originated. It is the same for its mineralogical composition. The fly ash used according to the invention may be of siliceous or calcic nature.
De préférence, la cendre volante utilisée selon la présente invention est choisie parmi celles telles que décrites dans la norme Européenne NF EN 197-1 de février 2001.  Preferably, the fly ash used according to the present invention is chosen from those as described in European Standard NF EN 197-1 of February 2001.
Les laitiers sont généralement obtenus par refroidissement rapide du laitier fondu provenant de la fusion du minerai de fer dans un haut fourneau.  Slags are generally obtained by rapidly cooling the molten slag from the smelting of iron ore in a blast furnace.
Les laitiers utilisés selon la présente invention peuvent être choisi parmi les laitiers granulés de haut fourneau selon la norme Européenne NF EN 197-1 de février 2001 paragraphe 5.2.2.  The slags used according to the present invention may be chosen from granulated blast furnace slags according to the European Standard NF EN 197-1 of February 2001, paragraph 5.2.2.
Les fumées de silice utilisées selon la présente invention peuvent être un matériau obtenu par réduction de quartz de grande pureté par du charbon dans des fours à arcs électriques utilisés pour la production de silicium et d'alliages de ferrosilicium. Les fumées de silice sont généralement formées de particules sphériques comprenant au moins 85 % en masse de silice amorphe.  The silica fumes used according to the present invention may be a material obtained by the reduction of high purity quartz by charcoal in electric arc furnaces used for the production of silicon and ferrosilicon alloys. The silica fumes are generally formed of spherical particles comprising at least 85% by mass of amorphous silica.
De préférence, les fumées de silice utilisées selon la présente invention sont choisies parmi les fumées de silice selon la norme Européenne NF EN 197-1 de février 2001 paragraphe 5.2.7.  Preferably, the silica fumes used according to the present invention are chosen from silica fumes according to the European standard NF EN 197-1 of February 2001, paragraph 5.2.7.
Les matériaux pouzzolaniques utilisés selon la présente invention peuvent être des substances naturelles siliceuses ou silico-alumineuses, ou une combinaison de celles-ci. Parmi les matériaux pouzzolaniques, on peut citer les pouzzolanes naturelles, qui sont en général des matériaux d'origine volcanique ou des roches sédimentaires, et les pouzzolanes naturelles calcinées, qui sont des matériaux d'origine volcanique, des argiles, des schistes ou des roches sédimentaires, activés thermiquement. Les matériaux pouzzolaniques utilisés selon l'invention peuvent être choisis parmi les ponces, les tuffs, les scories ou leurs mélanges.  The pozzolanic materials used according to the present invention may be natural siliceous or silico-aluminous substances, or a combination thereof. Pozzolanic materials include natural pozzolans, which are generally materials of volcanic origin or sedimentary rocks, and calcined natural pozzolans, which are materials of volcanic origin, clays, shales or rocks. sedimentary, thermally activated. The pozzolanic materials used according to the invention may be chosen from pumice, tuffs, slag or mixtures thereof.
De préférence, les matériaux pouzzolaniques utilisés selon la présente invention sont choisis parmi les matériaux pouzzolaniques selon la norme Européenne NF EN 197-1 de février 2001 paragraphe 5.2.3. De préférence, les additions minérales utilisées selon l'invention sont des matériaux contenant du carbonate de calcium, par exemple du calcaire (aussi appelé filler calcaire). Preferably, the pozzolanic materials used according to the present invention are chosen from pozzolanic materials according to European Standard NF EN 197-1 of February 2001, section 5.2.3. Preferably, the mineral additives used according to the invention are materials containing calcium carbonate, for example limestone (also called limestone filler).
Les argiles calcinées utilisées selon la présente invention peuvent résulter de la calcination d'une argile, la kaolinite, associée à différents minéraux (phyllosilicates, quartz, oxydes de fer) en proportions variables suivant les gisements. Ils peuvent être obtenus soit par calcination broyage soit par broyage calcination dans des unités de production à fours rotatifs, à plateaux ou par calcination dite « flash », par exemple. Ils sont essentiellement composés de particules de silicate d'alumine amorphe.  The calcined clays used according to the present invention can result from the calcination of a clay, kaolinite, associated with different minerals (phyllosilicates, quartz, iron oxides) in varying proportions depending on the deposits. They can be obtained either by grinding calcination or by grinding calcination in production units with rotary kilns, trays or so-called "flash" calcination, for example. They are essentially composed of amorphous alumina silicate particles.
De préférence, les argiles calcinées utilisés selon la présente invention peuvent être choisis parmi les métakaolins selon l'avant-projet de norme PR NF P 18-513 de décembre 2011.  Preferably, the calcined clays used according to the present invention may be chosen from metakaolins according to the preliminary draft standard PR NF P 18-513 of December 2011.
Selon une variante, le liant hydraulique de l'invention peut en outre comprendre du sulfate de calcium. According to one variant, the hydraulic binder of the invention may further comprise calcium sulphate.
Le sulfate de calcium utilisé inclut le gypse (sulfate de calcium dihydraté, The calcium sulphate used includes gypsum (calcium sulfate dihydrate,
CaS04.2H20), le semi-hydrate (CaS04.1/2H20), l'anhydrite (sulfate de calcium anhydre, CaS04) ou un de leurs mélanges. Le gypse et l'anhydrite existent à l'état naturel. Il est également possible d'utiliser un sulfate de calcium qui est un sous-produit de certains procédés industriels. CaSO 4 .2H 2 O), the hemihydrate (CaSO 4 .1 / 2H 2 O), the anhydrite (anhydrous calcium sulfate, CaSO 4 ) or a mixture thereof. Gypsum and anhydrite exist in their natural state. It is also possible to use a calcium sulphate which is a by-product of certain industrial processes.
En général, le liant hydraulique de l'invention comprend de 3 % à 28 % de sulfate de calcium en masse par rapport à la masse de clinker.  In general, the hydraulic binder of the invention comprises from 3% to 28% by weight of calcium sulphate relative to the weight of clinker.
Une teneur élevée en sulfate de calcium est généralement adoptée pour les ciments alumineux et sulfoalumineux. La nature chimique (gypse, semi-hydrate ou anhydrite) et le dosage en sulfate de calcium sont avantageusement ajustés en fonction du ciment pour éviter le gonflement des hydrates.  A high content of calcium sulphate is generally adopted for aluminous and sulphoaluminous cements. The chemical nature (gypsum, hemihydrate or anhydrite) and the calcium sulphate dosage are advantageously adjusted depending on the cement to prevent swelling of the hydrates.
Dans le cas où le clinker est un clinker Portland, le liant hydraulique de l'invention comprend de 1 % à 8 %, de préférence de 2 % à 5 % de sulfate de calcium en masse par rapport à la masse de clinker.  In the case where the clinker is a Portland clinker, the hydraulic binder of the invention comprises from 1% to 8%, preferably from 2% to 5% by mass of calcium sulphate relative to the mass of clinker.
Un liant selon l'invention est généralement obtenu par co-broyage d'un clinker et de sulfate de calcium. Eléments métalliques A binder according to the invention is generally obtained by co-grinding a clinker and calcium sulphate. Metallic elements
Une composition hydraulique à l'état durci selon l'invention peut comprendre des éléments métalliques, comme par exemple des armatures, notamment des armatures pour béton armé selon la norme européenne NF EN 1992-1-1 d'octobre 2005.  A hydraulic composition in the cured state according to the invention may comprise metal elements, such as reinforcements, in particular reinforced concrete reinforcements according to European Standard NF EN 1992-1-1 of October 2005.
Les armatures peuvent se présenter sous forme de barres, de treillis soudés ou assemblage de barres, de ferraillages. Les jonctions des barres peuvent être assurées par recouvrement, par dispositif de raboutage, par soudure, par ligature, par sertissage ou tout autre moyen.  The frames can be in the form of bars, welded mesh or assembly of bars, reinforcement. The junctions of the bars may be provided by overlapping, splicing, soldering, ligation, crimping or any other means.
Selon une variante de l'invention, les éléments métalliques sont des fibres d'acier tréfilé remplaçant complètement ou partiellement des armatures métalliques ordinaires dans certaines applications (dallages, béton projeté ou béton de réparation).  According to a variant of the invention, the metal elements are drawn steel fibers completely or partially replacing ordinary metal reinforcements in certain applications (pavements, shotcrete or repair concrete).
Granulats aggregates
Une composition hydraulique selon l'invention peut comprendre des granulats.  A hydraulic composition according to the invention may comprise aggregates.
Les granulats éventuellement utilisés dans la composition selon l'invention incluent du sable (dont les particules ont généralement une taille maximale (Dmax) inférieure ou égale à 4 mm), et éventuellement des gravillons (dont les particules ont généralement une taille minimale (Dmin) supérieure à 4 mm et de préférence une Dmax inférieure ou égale à 20 mm). Les granulats utilisés dans la composition selon l'invention sont généralement conformes à la norme européenne NF EN 12620 d'août 2003, et sont d'origine naturelle ou artificielle. Les granulats peuvent être également du bois.  The aggregates optionally used in the composition according to the invention include sand (whose particles generally have a maximum size (Dmax) less than or equal to 4 mm), and possibly chippings (whose particles generally have a minimum size (Dmin) greater than 4 mm and preferably a Dmax less than or equal to 20 mm). The aggregates used in the composition according to the invention are generally in accordance with European Standard NF EN 12620 of August 2003, and are of natural or artificial origin. Aggregates can also be wood.
Adjuvants admixtures
Une composition hydraulique selon l'invention peut comprendre des adjuvants conventionnels sous réserve de leur compatibilité avec la ou les polyacrylamide(s) réticulé(s) requis selon l'invention.  A hydraulic composition according to the invention may comprise conventional adjuvants subject to their compatibility with the crosslinked polyacrylamide (s) required according to the invention.
Les adjuvants utilisables dans la composition hydraulique selon l'invention peuvent par exemple être un de ceux décrits dans les normes européennes NF EN 934-2 de septembre 2002, NF EN 934-3 de novembre 2009 ou NF EN 934-4 d'août 2009. Avantageusement, la composition hydraulique selon l'invention comprend au moins un adjuvant pour composition hydraulique : un accélérateur, un agent entraîneur d'air, un agent viscosant, un retardateur, un inertant des argiles, un agent antimousse, un plastifiant et/ou un superplastifiant.  The adjuvants that can be used in the hydraulic composition according to the invention can for example be one of those described in European standards NF EN 934-2 of September 2002, NF EN 934-3 of November 2009 or NF EN 934-4 of August 2009. Advantageously, the hydraulic composition according to the invention comprises at least one adjuvant for hydraulic composition: an accelerator, an air-entraining agent, a viscosifying agent, a retarder, an inerting clays, an antifoaming agent, a plasticizer and / or a superplasticizer.
De préférence, la composition hydraulique selon l'invention comprend au moins un agent antimousse évitant l'entraînement d'air dans la composition. Les inertants des argiles sont des composés qui permettent de réduire ou de prévenir les effets néfastes des argiles sur les propriétés des liants hydrauliques. Les inertants des argiles incluent ceux décrits dans WO 2006/032785 et WO 2006/032786. Preferably, the hydraulic composition according to the invention comprises at least one antifoam agent avoiding the entrainment of air in the composition. Inerting clays are compounds that reduce or prevent the harmful effects of clays on the properties of hydraulic binders. Inerting clays include those described in WO 2006/032785 and WO 2006/032786.
Le terme "superplastifiant" tel qu'utilisé dans la présente description et les revendications qui l'accompagnent est à comprendre comme incluant à la fois les réducteurs d'eau et les superplastifiants tels que décrits dans le livre intitulé « Concrète Admixtures Handbook, Properties Science and Technology », V.S. Ramachandran, Noyés Publications, 1984.  The term "superplasticizer" as used in the present specification and accompanying claims is to be understood to include both water reducers and superplasticizers as described in the book entitled "Concrete Admixtures Handbook, Properties Science". and Technology, "VS Ramachandran, Noyes Publications, 1984.
Un réducteur d'eau est défini comme un adjuvant qui réduit de typiquement 10 % à 15 % la quantité d'eau de gâchage d'un béton pour une ouvrabilité donnée. Les réducteurs d'eau incluent, par exemple les lignosulfonates, les acides hydroxycarboxyliques, les glucides et d'autres composés organiques spécialisés, par exemple le glycérol, l'alcool polyvinylique, l'alumino-méthyl-siliconate de sodium, l'acide sulfanilique et la caséine.  A water reducer is defined as an adjuvant which typically reduces the amount of mixing water of a concrete for a given workability from typically 10% to 15%. Water reducers include, for example, lignosulfonates, hydroxycarboxylic acids, carbohydrates and other specialized organic compounds, for example glycerol, polyvinyl alcohol, sodium alumino-methyl-siliconate, sulfanilic acid and casein.
Les superplastifiants appartiennent à une nouvelle classe de réducteurs d'eau, chimiquement différents des réducteurs d'eau normaux et capables de réduire les quantités d'eau d'environ 30 %. Les superplastifiants ont été globalement classés en quatre groupes : les condensais sulfonés de naphtalène formaldéhyde (SNF) (généralement un sel de sodium) ; les condensais sulfonés de mélamine formaldéhyde (SMF) ; les lignosulfonates modifiés (MLS) ; et les autres. Des superplastifiants plus récents incluent des composés polycarboxyliques comme les polycarboxylates, par exemple les polyacrylates. Un superplastifiant est de préférence un superplastifiant nouvelle génération, par exemple un copolymère contenant un polyéthylène glycol comme chaîne greffée et des fonctions carboxyliques dans la chaîne principale comme un éther polycarboxylique. Les polycarboxylates-polysulfonates de sodium et les polyacrylates de sodium peuvent aussi être utilisés. Les dérivés d'acide phosphonique, les polycarboxylate-polysulfonates de sodium et les polyacrylates de sodium peuvent aussi être utilisés. La quantité nécessaire de superplastifiant dépend généralement de la réactivité du ciment. Plus la réactivité est faible, plus la quantité nécessaire de superplastifiant est faible. Pour réduire la quantité totale de sels alcalins, le superplastifiant peut être utilisé sous forme de sel de calcium plutôt que sous forme de sel de sodium.  Superplasticizers belong to a new class of water reducers, chemically different from normal water reducers and able to reduce water amounts by about 30%. Superplasticizers were broadly classified into four groups: sulfonated condensates of naphthalene formaldehyde (SNF) (usually a sodium salt); sulphonated condensates of melamine formaldehyde (SMF); modified lignosulfonates (MLS); And the others. More recent superplasticizers include polycarboxylic compounds such as polycarboxylates, for example polyacrylates. A superplasticizer is preferably a new generation superplasticizer, for example a copolymer containing a polyethylene glycol as a grafted chain and carboxylic functions in the main chain as a polycarboxylic ether. Sodium polycarboxylate polysulfonates and sodium polyacrylates can also be used. Phosphonic acid derivatives, sodium polycarboxylate polysulfonates and sodium polyacrylates may also be used. The required amount of superplasticizer usually depends on the reactivity of the cement. The lower the reactivity, the lower the required amount of superplasticizer. To reduce the total amount of alkaline salts, the superplasticizer can be used as a calcium salt rather than as a sodium salt.
D'autres additifs peuvent être incorporés dans la composition selon l'invention, par exemple, un agent antimousse (par exemple polydiméthylsiloxane ; le triisobutylphosphonate). Les agents antimousses comprennent également les silicones sous forme de solution, de. solide ou de préférence sous forme de résine, d'huile ou d'émulsion, de préférence dans l'eau. Plus particulièrement adaptés sont les silicones comprenant des groupements (RSiOo,5) et (R2SiO). Other additives may be incorporated in the composition according to the invention, for example an antifoaming agent (for example polydimethylsiloxane, triisobutylphosphonate). Antifoam agents also include silicones in the form of a solution of. solid or preferably in the form of resin, oil or emulsion, preferably in water. More particularly suitable are silicones comprising (RSiOo, 5) and (R 2 SiO) groups.
Dans ces formules, les radicaux R, qui peuvent être identiques ou différents, sont de préférence un atome d'hydrogène ou un groupe alkyle de 1 à 8 atomes de carbone, le groupe méthyle étant préféré. Le nombre de motifs est de préférence de 30 à 120.  In these formulas, the R radicals, which may be the same or different, are preferably a hydrogen atom or an alkyl group of 1 to 8 carbon atoms, the methyl group being preferred. The number of patterns is preferably from 30 to 120.
La quantité d'un tel agent dans le ciment final est généralement d'au plus 5 parties en poids par rapport au ciment.  The amount of such an agent in the final cement is generally at most 5 parts by weight relative to the cement.
Selon un mode de réalisation préféré, une composition hydraulique selon l'invention comprend : According to a preferred embodiment, a hydraulic composition according to the invention comprises:
un liant hydraulique comprenant un clinker Portland, du sulfate de calcium, éventuellement un filler calcaire ou une autre addition minérale, la proportion massique en clinker dans le liant étant comprise de 30 % à 85 %, au moins un polyacrylamide réticulé sous la forme d'une poudre de particules ayant une taille moyenne comprise de 300 μηι à 2 000 μηι, ledit polyacrylamide réticulé ayant un taux d'azote supérieur ou égal à 4 % en masse par rapport à la masse du polyacrylamide, selon un rapport pondéral polyacrylamide(s) réticulé(s)/liant compris de 0,01 % à 5,0 %,  a hydraulic binder comprising a Portland clinker, calcium sulphate, optionally a limestone filler or another mineral addition, the clinker mass proportion in the binder being from 30% to 85%, at least one crosslinked polyacrylamide in the form of a powder of particles having a mean size of from 300 μηι to 2,000 μηι, said crosslinked polyacrylamide having a nitrogen content greater than or equal to 4% by weight relative to the weight of the polyacrylamide, in a weight ratio polyacrylamide (s) cross-linked (s) / binder from 0.01% to 5.0%,
de l'eau, selon une proportion telle que le rapport massique eau/liant est compris de 0,4 à 1,2, de préférence de 0,3 à 0,7,  water, in a proportion such that the weight ratio water / binder is from 0.4 to 1.2, preferably from 0.3 to 0.7,
éventuellement un granulat tel qu'un sable,  optionally a granulate such as sand,
éventuellement un agent superplastifiant, et  optionally a superplasticizer, and
éventuellement un agent antimousse. Une composition hydraulique selon l'invention peut être préparée en mettant en contact au moins un liant hydraulique, au moins un polyacrylamide réticulé sous la forme d'une poudre de particules ayant une taille moyenne comprise de 300 μηι à 2 000 μηι, ledit polyacrylamide réticulé ayant un taux d'azote supérieur ou égal à 4 % en masse par rapport à la masse du polyacrylamide, selon un rapport pondéral polyacrylamide(s) réticulé(s)/liant compris de 0,01 % à 5,0 %, et de l'eau.  optionally an antifoaming agent. A hydraulic composition according to the invention may be prepared by contacting at least one hydraulic binder, at least one crosslinked polyacrylamide in the form of a powder of particles having an average size of 300 μηι to 2,000 μηι, said crosslinked polyacrylamide having a nitrogen content greater than or equal to 4% by mass relative to the weight of the polyacrylamide, in a weight ratio of polyacrylamide (s) crosslinked (s) / binder of 0.01% to 5.0%, and of the water.
Selon un mode de réalisation préféré, le ou les polyacrylamide(s) réticulé(s) est (sont) mis en œuvre sous la forme d'une poudre. De préférence, le liant hydraulique et le ou les polyacrylamide(s) réticulé(s) sont préalablement mis en contact sous forme sèche, avantageusement sous forme de poudre, avant que le mélange obtenu ne soit mis en contact d'eau. La composition hydraulique selon l'invention peut être utilisée directement sur chantier à l'état frais et coulée dans un coffrage adapté à l'application visée, ou utilisée en usine de préfabrication. According to a preferred embodiment, the crosslinked polyacrylamide (s) is (are) used in the form of a powder. Preferably, the hydraulic binder and the crosslinked polyacrylamide (s) are (are) previously brought into contact in dry form, advantageously in the form of a powder, before the mixture obtained is brought into contact with water. The hydraulic composition according to the invention can be used directly on site in the fresh state and cast in a formwork adapted to the intended application, or used in prefabrication plant.
Le gâchage de la composition hydraulique peut être effectué selon des méthodes connues de l'homme du métier.  The mixing of the hydraulic composition can be carried out according to methods known to those skilled in the art.
Une composition hydraulique selon la présente invention peut être mise en forme pour produire, après hydratation et durcissement, un objet mis en forme pour le domaine de la construction. A hydraulic composition according to the present invention can be shaped to produce, after hydration and hardening, a shaped object for the field of construction.
Les objets mis en forme pour le domaine de la construction incluent, par exemple, un sol, une chape, une fondation, un mur, une cloison, un plafond, une poutre, un plan de travail, un pilier, une pile de pont, un parpaing, une canalisation, un poteau, un escalier, un panneau, une corniche, un moule, un élément de voirie (par exemple une bordure de trottoir), ou un revêtement (par exemple de route ou de mur).  Objects shaped for the field of construction include, for example, a floor, a screed, a foundation, a wall, a partition, a ceiling, a beam, a worktop, a pillar, a bridge stack, a cinder block, a pipe, a pole, a staircase, a panel, a cornice, a mold, a road element (for example a curb), or a covering (for example road or wall).
Dans la présente description, y compris les revendications qui l'accompagnent, les pourcentages sont exprimés par masse, sauf quand il en est autrement spécifié.  In the present description, including the accompanying claims, the percentages are by mass unless otherwise specified.
Les exemples suivants illustrent la réalisation de l'invention.  The following examples illustrate the embodiment of the invention.
EXEMPLES  EXAMPLES
Exemple 1 - Préparation des éprouvettes de mortier Example 1 - Preparation of mortar specimens
Des éprouvettes de mortier ont été préparées à partir d'une composition hydraulique comprenant un liant hydraulique à faible taux de clinker (substitué à 35 % par un filler calcaire). Le ratio eau/liant est égal à 0,55 et le dosage en TiBP (agent antimousse) est de 0,09 %/liant.  Mortar specimens were prepared from a hydraulic composition comprising a low clinker hydraulic binder (35% substituted by a calcareous filler). The water / binder ratio is equal to 0.55 and the TiBP (defoaming agent) dosage is 0.09% / binder.
La composition des éprouvettes est indiquée dans le Tableau 1 et les caractéristiques du ciment et du sable sont indiquées dans les Tableaux 2 et 3. Tableau 1 The composition of the specimens is shown in Table 1 and the characteristics of the cement and sand are shown in Tables 2 and 3. Table 1
Figure imgf000016_0002
Figure imgf000016_0002
Tableau 2 : Caractéristiques du CEM I 52.5 N CE CP2 NF, Saint Pierre La Cour Table 2: Characteristics of the CEM I 52.5 N CE CP2 NF, Saint Pierre The Court
Figure imgf000016_0001
Figure imgf000016_0001
Figure imgf000017_0001
Tableau 3 : Caractéristi ues du sable normalisé EN 2620)
Figure imgf000017_0001
Table 3: Characteristics of standardized sand EN 2620)
Figure imgf000018_0001
Figure imgf000018_0001
Les polyacrylamides réticulés utilisés (fournis par la société SNF) sont décrits dans le Tableau 4 suivant : The crosslinked polyacrylamides used (supplied by SNF) are described in Table 4 below:
Tableau 4  Table 4
Nom Taux Granulométrie Degré de commercial d'azote ( %) (μηι) réticulation Name Rate Granulometry Degree of commercial nitrogen (%) (μ η ι) crosslinking
SAP1 Aquasorb 3005  SAP1 Aquasorb 3005
12,0 >300, <600 ++  12.0> 300, <600 ++
Max  Max
SAP2 Floset 27 CC 10 >300, <600 ++  SAP2 Floset 27 CC 10> 300, <600 ++
SAP3 Floset 27 CB 10 >300, <1000 ++ Protocole de préparation des eprouvettes SAP3 Floset 27 CB 10> 300, <1000 ++ Protocol for the preparation of test specimens
Le sable a été mis dans le bol d'un malaxeur Perrier type 32 avec l'eau de prémouillage. Le malaxage a débuté et a été maintenu à petite vitesse pendant 1 minute.  The sand was put into the bowl of a Perrier type 32 mixer with prewetting water. Mixing started and was maintained at low speed for 1 minute.
Le malaxage a ensuite été stoppé pendant 4 minutes.  The kneading was then stopped for 4 minutes.
Le liant hydraulique (ciment+fïller) et le polyacrylamide réticulé en poudre ont été ajoutés et le malaxage a repris à petite vitesse pendant 1 minute.  The hydraulic binder (cement + filter) and the cross-linked polyacrylamide powder were added and mixing was resumed at low speed for 1 minute.
L'eau de gâchage, comprenant les adjuvants (antimousse et plastifiant), a ensuite été ajoutée en 30 secondes tout en malaxant à petite vitesse.  The mixing water, comprising the adjuvants (antifoam and plasticizer), was then added in 30 seconds while mixing at low speed.
Le mélange a été malaxé à grande vitesse pendant 1 minute, pour obtenir un mortier.  The mixture was kneaded at high speed for 1 minute to obtain a mortar.
Les formulations préparées sont décrites dans le Tableau 5 suivant : The formulations prepared are described in the following Table 5:
Tableau 5  Table 5
Figure imgf000019_0001
Figure imgf000019_0001
Le mortier a ensuite été coulé dans des moules en polystyrène de dimensions 4 cm x 4 cm x 16 cm (sans vibration), afin d'obtenir 6 éprouvettes de béton (démoulées après 24 h à 20 °C à 100 % d'humidité relative). The mortar was then poured into polystyrene molds measuring 4 cm x 4 cm x 16 cm (without vibration) to obtain 6 concrete specimens (demolded after 24 h at 20 ° C at 100% relative humidity). ).
Exemple 2 - Mesure de la carbonatation des éprouvettes de mortier Example 2 - Measurement of carbonation of the mortar specimens
Protocole de mesure  Measurement protocol
Les éprouvettes de mortier ont ensuite été placées dans des conditions de carbonatation accélérée. Après 6 jours de cure en armoire humide à 100 % d'humidité relative et 20 °C, les éprouvettes ont été placées dans un caisson de carbonatation (cuve rectangulaire en PEHD, de 576 litres de capacité, muni d'un couvercle étanche), dont l'atmosphère a été enrichie en CO2 (10 % +/- 0,5 % de C02 dans le volume d'air du caisson), 20 °C +/- 1 °C et 65 % +/- 5 % d'humidité relative. The mortar specimens were then placed under accelerated carbonation conditions. After 6 days of curing in a wet cabinet at 100% relative humidity and 20 ° C., the test pieces were placed in a carbonation box (rectangular HDPE tank, with a capacity of 576 liters, equipped with a tight-fitting lid). whose atmosphere has been enriched with CO 2 (10% +/- 0.5% C0 2 in the air volume of the chamber), 20 ° C +/- 1 ° C and 65% +/- 5% relative humidity.
La régulation en température a été assurée par le fait que le caisson était disposé dans un laboratoire régulé à 20 +/-1 °C. Le taux d'humidité relative a été régulé par un bac rempli de sel de nitrate d'ammonium saturé d'eau, ce bac étant positionné au fond du caisson, sur toute la surface disponible. Pour le CO2, le caisson a été connecté à un réseau alimenté par des bouteilles remplies d'un mélange 50 % CO2 / 50 % d'azote sous pression. Une centrale de détente a permis de délivrer le mélange à 1 bar de pression relative dans le réseau. L'introduction du gaz a été gérée de façon automatique par un analyseur de CO2 gazeux qui a analysé en continu l'atmosphère du caisson (analyseur mural, de la marque ABISS, modèle LMP 320, fourni par la société PBI Datasensor). A chaque introduction de gaz, une autre électro vanne s'ouvrait pour évacuer le surplus de gaz vers un vide sanitaire extérieur au laboratoire, ceci afin d'éviter toute surpression dans le caisson. Un ventilateur a fonctionné en continu pour avoir une répartition homogène du CO2 gazeux dans l'atmosphère du caisson. The temperature regulation was ensured by the fact that the box was placed in a laboratory regulated at 20 +/- 1 ° C. The relative humidity was regulated by a tray filled with ammonium nitrate salt saturated with water, this tray being positioned at the bottom of the box, over the entire available surface. For CO 2 , the box was connected to a network fed by bottles filled with a mixture of 50% CO 2 /50% nitrogen under pressure. An expansion unit has enabled the mixture to be delivered at 1 bar of relative pressure in the network. The introduction of the gas was managed automatically by a CO 2 gas analyzer which continuously analyzed the atmosphere of the box (ABISS wall scanner, model LMP 320, supplied by the company PBI Datasensor). At each introduction of gas, another electro valve was opened to evacuate excess gas to a crawl space outside the laboratory, this to prevent overpressure in the box. A fan operated continuously to have a homogeneous distribution of CO 2 gas in the atmosphere of the box.
A différentes échéances, les éprouvettes ont été sorties du caisson de carbonatation et fendues à l'aide d'un coupe-pavé hydraulique pour déterminer la profondeur de carbonatation.  At different times, the specimens were taken out of the carbonation box and split with a hydraulic cutter to determine the depth of carbonation.
La résistance à la carbonatation a été estimée en mesurant la profondeur de carbonatation des éprouvettes. Cette profondeur a été mesurée après différentes périodes d'exposition des éprouvettes dans le caisson enrichi en CO2 gazeux. Resistance to carbonation was estimated by measuring the carbonation depth of the specimens. This depth was measured after different periods of exposure of the specimens in the box enriched in gaseous CO 2 .
Plus cette profondeur est élevée, moins le béton est résistant à la carbonatation, et plus le risque de corrosion des armatures de structure est élevé. Le matériau est dit carbonaté lorsque son pH est inférieur ou égal à 9. Ceci est visualisé en pulvérisant une solution de phénolphtaléine à 0,5 % diluée dans un mélange composé à 50 % d'eau déminéralisée et 50 % d'éthanol. La phénolphtaléine est un indicateur coloré qui vire au rose pourpre lorsque le pH est supérieur à 9 et reste incolore lorsque le pH est inférieur à 9. Les zones de béton carbonatées sont donc celles qui restent incolores après pulvérisation de la suspension de phénolphtaléine. Les profondeurs de béton et mortier carbonatés ont été mesurées en plusieurs zones. La moyenne arithmétique des valeurs obtenues a été calculée. Résultats The higher this depth, the less resistant the concrete is to carbonation, and the greater the risk of structural reinforcement corrosion. The material is said to be carbonated when its pH is less than or equal to 9. This is visualized by spraying a solution of 0.5% phenolphthalein diluted in a mixture composed of 50% demineralised water and 50% ethanol. Phenolphthalein is a colored indicator that changes to purple pink when the pH is above 9 and remains colorless when the pH is below 9. The carbonated concrete zones are therefore those that remain colorless after spraying the phenolphthalein suspension. The depths of carbonate concrete and mortar were measured in several zones. The arithmetic mean of the values obtained was calculated. Results
Les résultats de la mesure de profondeur de carbonatation (en mm) en fonction du temps (en jour) en fonction du type de polyacrylamide réticulé sont indiquées dans le Tableau 6 suivant :  The results of the measurement of carbonation depth (in mm) as a function of time (in days) as a function of the type of crosslinked polyacrylamide are indicated in the following Table 6:
Tableau 6  Table 6
Figure imgf000021_0001
Figure imgf000021_0001
Les polyacrylamides réticulés ont conduit à des profondeurs de carbonatation significativement réduites par rapport au témoi sans polyacrylamide réticulé.  The crosslinked polyacrylamides led to significantly reduced carbonation depths compared to the crosslinked polyacrylamide-free sample.

Claims

REVENDICATIONS
1. Utilisation d'au moins un polyacrylamide réticulé, sous la forme d'une poudre de particules ayant une taille moyenne comprise de 300 μηι à 2 000 μηι, ledit polyacrylamide réticulé ayant un taux d'azote supérieur ou égal à 4 % en masse par rapport à la masse dudit polyacrylamide, en association avec au moins un liant hydraulique dans une composition hydraulique, pour réduire et/ou prévenir la carbonatation au sein de ladite composition hydraulique, ledit ou lesdits polyacrylamide(s) réticulé(s) étant présent(s) dans ladite composition hydraulique selon un rapport pondéral polyacrylamide(s) réticulé(s)/liant compris de 0,01 % à 5,0 %. 1. Use of at least one crosslinked polyacrylamide, in the form of a powder of particles having an average size of from 300 μηι to 2,000 μηι, said crosslinked polyacrylamide having a nitrogen content greater than or equal to 4% by weight with respect to the mass of said polyacrylamide, in combination with at least one hydraulic binder in a hydraulic composition, for reducing and / or preventing carbonation within said hydraulic composition, said at least one crosslinked polyacrylamide (s) being present ( s) in said hydraulic composition in a weight ratio polyacrylamide (s) crosslinked (s) / binder of 0.01% to 5.0%.
2. Utilisation selon la revendication 1, dans laquelle la composition hydraulique comprend en outre de l'eau, de préférence selon un rapport massique eau/liant compris de 0,4 à 1,2. 2. Use according to claim 1, wherein the hydraulic composition further comprises water, preferably in a weight ratio water / binder of 0.4 to 1.2.
3. Utilisation selon la revendication 1 ou 2, dans laquelle la composition hydraulique comprend en outre des éléments métalliques, de préférence des armatures. 3. Use according to claim 1 or 2, wherein the hydraulic composition further comprises metal elements, preferably reinforcements.
4. Utilisation selon l'une quelconque des revendications précédentes, dans laquelle le ou les polyacrylamide(s) réticulé(s) est (sont) obtenus par polymérisation à partir d'un mélange comprenant au moins un monomère acrylamide et au moins un agent réticulant. 4. Use according to any one of the preceding claims, wherein the crosslinked polyacrylamide (s) is (are) obtained by polymerization from a mixture comprising at least one acrylamide monomer and at least one crosslinking agent. .
5. Utilisation selon l'une quelconque des revendications précédentes, dans laquelle le ou les polyacrylamide(s) réticulé(s) est un copolymère comprenant des unités monomères acrylamide et des unités monomères acide acrylique et/ou acrylate, de préférence des unités monomères acrylamide et/ou des unités monomères acrylate de métal alcalin. 5. Use according to any one of the preceding claims, wherein the crosslinked polyacrylamide (s) is a copolymer comprising acrylamide monomer units and acrylic acid and / or acrylate monomer units, preferably acrylamide monomeric units. and / or alkali metal acrylate monomer units.
6. Utilisation selon l'une quelconque des revendications précédentes, dans laquelle le liant hydraulique comprend au moins un clinker, de préférence un clinker Portland. 6. Use according to any one of the preceding claims, wherein the hydraulic binder comprises at least one clinker, preferably a Portland clinker.
7. Utilisation selon la revendication précédente, dans laquelle la proportion massique en clinker dans le liant hydraulique est comprise de 30 % à 85 % par rapport à la masse dudit liant. 7. Use according to the preceding claim, wherein the mass proportion of clinker in the hydraulic binder is from 30% to 85% relative to the mass of said binder.
8. Utilisation selon l'une quelconque des revendications précédentes, dans laquelle le rapport pondéral polyacrylamide(s) réticulé(s)/liant est compris de 0,05 % à 2,0 %. 8. Use according to any one of the preceding claims, wherein the weight ratio polyacrylamide (s) crosslinked (s) / binder is from 0.05% to 2.0%.
9. Utilisation selon l'une quelconque des revendications précédentes, dans laquelle le liant hydraulique comprend en outre au moins une addition minérale, qui est de préférence choisie dans le groupe constitué par les laitiers, les pouzzolanes, les cendres volantes, les schistes calcinés, les matériaux à base de carbonate de calcium, les fumées de silice, les métakaolins, les cendres de biomasse et leurs mélanges. 9. Use according to any one of the preceding claims, wherein the hydraulic binder further comprises at least one mineral addition, which is preferably selected from the group consisting of slags, pozzolans, fly ash, calcined schists, calcium carbonate materials, silica fumes, metakaolins, biomass ash and mixtures thereof.
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