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
  • 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
  • C04B28/06—Aluminous cements
  • C04B28/065—Calcium aluminosulfate cements, e.g. cements hydrating into ettringite
• • 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
  • C04B24/2641—Polyacrylates; Polymethacrylates
  • C04B24/2647—Polyacrylates; Polymethacrylates containing polyether side chains
• • 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
  • C04B2103/0059—Graft (co-)polymers
  • C04B2103/006—Comb 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
  • C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
  • C04B2103/20—Retarders
  • C04B2103/22—Set retarders
• • 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
  • C04B2103/30—Water reducers, plasticisers, air-entrainers, flow improvers
• • 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
  • C04B2111/00034—Physico-chemical characteristics of the mixtures
  • C04B2111/00103—Self-compacting mixtures
• • 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
  • C04B2111/60—Flooring materials
  • C04B2111/62—Self-levelling compositions

Definitions

• the present invention relates to the field of sulfo-aluminous cements and their adjuvants.
• the present invention relates more particularly to the use of adjuvants making it possible to obtain both a fluidification and a setting delay.
• Sulpho-aluminous cements have appeared in China where they were produced industrially from the 1970s. Because of their expansive property, they were initially used in the production of self-constrained cement pipes.
• these cements are used in many applications because of their specific properties such as: short setting time, strong short-term strengths, high heat of hydration, low porosity and alkalinity. All these properties derive from the composition of these cements, rich in yeelimite. Indeed, yeelimite causes the homogeneous formation of large quantities of ettringite from the beginning of the hydration of the cement and forms a network in the cement.
• Sulphoaluminum cements are known to have a particularly short setting time. It is necessary for those skilled in the art to increase and control the setting time of compositions based on sulfo-aluminous cements.
• setting retarding adjuvants are well known to those skilled in the art, in particular salts of citrate or tartrate.
• a first object of the invention is therefore to provide a setting retarding adjuvant for increasing the setting time of hydraulic binders based on sulfo-aluminous cement, or containing exclusively sulfoaluminous cement, while respecting the constraints. required fluidity according to the uses of these cements.
• Another object of the invention is to provide a combination of compatible retarding additives and fluidifiers, applicable for compositions containing sulfo-aluminous cement or exclusively containing sulfo-aluminous cement.
• the present invention thus relates to the use of a polycarboxylate polymer as a fluidizing and retardant setting of a hydraulic binder comprising predominantly a sulfo-aluminous clinker, sulfo-aluminous clinker containing at least 30% by weight phase Yeelimite.
• the term "retarding the setting” means repelling in time the moment when the hydraulic binder becomes solid.
• the hydration reactions that take place in the cementitious composition lead to the formation of solid hydrates, especially ettringite in the case of sulfo-aluminous cements.
• Increasing the amount of these hydrates causes stiffening of the hydraulic binder, leading to setting.
• the setting time is measured using a texturometer.
• polycarboxylate refers here to an organic compound consisting of a main hydrocarbon chain and functionalized in particular by carboxylate groups. These compounds are well known in the field of the adjuvantation of cements as superplasticizers, the superplasticizers being a class of fluidifying adjuvants.
• hydroaulic binder is interpreted in the sense of EN 206-1 (March 2006). That is, it refers to a finely ground mineral material which, after being mixed with water, forms a paste that sets and hardens by the effect of chemical reaction and hydration process, and which, after curing, retains its strength and stability even under water. In the present invention, the hydraulic binder is synonymous with "cement”.
• This cement is the combination, finely ground, of at least one clinker, possibly at least one calcium sulphate, and optionally of one or more pozzolanic mineral additions, such as blast furnace slag, fly ash, silica fumes or pozzolans.
• clinker refers to the product of high temperature cooking of a mixture of minerals.
• a sulfo-aluminous clinker is the product resulting from the baking at about 1300 ° C, a mixture composed in particular of limestone, bauxite and gypsum.
• the "yeelimite”, or ye'elimite, is a mineralogical phase of formula Ca 4 AI 6 0i 2 (SO 4) present in the sulfo-aluminous clinker and designated in cement notation by the symbol C4A3 $.
• the effects of admixtures vary according to the composition of the hydraulic binders and particularly the clinkers that compose them. It is important in the context of the present invention that the mass proportion of sulfoaluminous clinker in the hydraulic binder remains at least majority, that is to say greater than 50% by weight of the hydraulic binder. All percentages given in this text are percentages by mass.
• a polymer according to the present invention is such that said hydraulic binder comprises at least 60% by weight, especially at least 80% by weight, preferably at least 90% by weight of sulfo-aluminous clinker.
• polycarboxylate as a fluidizing and retarding agent for a hydraulic binder composed of different types of clinkers, for example sulpho-aluminous clinker mixed with Portland clinker, and / or aluminous clinker.
• Portland clinker is the product of cooking at about 1450 ° C of a mixture composed in particular of limestone and clay.
• An aluminous clinker is the product of cooking at about 1500-1600 ° C of a mixture composed in particular of limestone and bauxite.
• said hydraulic binder may thus comprise less than 50%, preferably not more than 40%, more preferably 10 to 20% Portland clinker, or a mass proportion of less than 10% Portland cement.
• Said hydraulic binder may comprise less than 50%, preferably not more than 40%, preferably 10 to 20% aluminous clinker, or a mass proportion of less than 10% aluminous clinker.
• the hydraulic binder according to the present invention may not comprise Portland clinker and / or aluminous clinker.
• the use of the polycarboxylate is more particularly effective when said sulfo-aluminous clinker comprises at least 40%, especially 40 to 80%, preferably 50 to 70% by weight of the elite.
• Yelimite is an essential mineral phase within the meaning of the present invention, but it does not constitute the entirety of the sulfo-aluminous clinker.
• sulfo-aluminous clinker also contains belite, designated C2S in cement notation.
• a polymer according to the present invention is also characterized in that said polycarboxylate polymer has a comb-like structure.
• comb type refers to the general molecular structure of the polymer which has the same shape as the object, namely a main chain and side groups. These carboxylate side groups may be engaged in ester or amide chemical bonds with functionalizing groups. The rate of functionalization indicates the percentage of carboxylate side groups involved in such chemical bonds.
• said polycarboxylate polymer according to the invention advantageously has a degree of functionalization of from 1 to 80%, especially from 10 to 80%, more particularly from 10 to 50%, preferably from 15 to 50%, and more preferably from 15 to 30%.
• said polycarboxylate polymer has functionalization with polyalkoxide type chains, especially polyethylene oxide.
• Functionalizing groups of polyethylene oxide type make it possible to increase the solubility of the polymer in the aqueous phase, while the non-functionalized carboxylate side groups interact electrostatically with the surface of the cement particles.
• the molecular weight of the chains functionalizing the side groups is correlated with the steric repulsion that the polymer will cause. This steric repulsion phenomenon makes it possible to move the particles of cement away from one another and to ensure a superplasticizing effect.
• Said polycarboxylate polymer therefore advantageously has functionalization with chains having an average molecular mass ranging from 750 to 7000 g / mol, preferably from 1000 to 6000 g / mol.
• polycarboxylate adjuvant according to the present invention is in particular implementation for the realization of mortar, traditional screed, or self-placing fluid screed.
• the term "traditional screed” designates a mortar layer comprising in particular cement, water, sand, optionally mineral additives, and possibly at least one adjuvant, with or without a mesh.
• the mortar does not spread by itself under the action of gravity, and is not pumpable.
• self-setting fluid screed designates a mortar comprising in particular cement, water, sand, possibly mineral additives (or filler) and optionally at least one adjuvant, with or without a mesh.
• the mortar is fluid and spreads itself under the action of gravity.
• sand is meant aggregates with a diameter of less than or equal to 4 mm.
• Standard additions or “filler” means finely divided mineral particles used in concrete in order to improve certain properties or to confer particular properties on it (Standard EN 206-1 paragraph 3.1.23, March 2006, Standard NF P 18-501, paragraph 3, March 1992).
• polycarboxylate can also be implemented for the production of concrete, such as ready-mixed concrete, in particular self-placing concrete.
• crete refers to a mixture comprising cement, water, sand, gravel, possibly mineral additives and possibly at least one adjuvant.
• grain is meant aggregates with a diameter greater than 4 mm.
• BPE ready-mix concrete
• self-placing concrete refers to a concrete that flows and compacts by gravitational effect alone, capable of filling a formwork while maintaining its homogeneity (Standard NF EN 206.9, June 2010). More particularly, the polycarboxylate is used in said hydraulic binder in a mass proportion of between 0.01 and 3%, especially 0.05 and 3%, more particularly between 0.05 and 1.5%, particularly between 0, 1 and 1% with respect to the hydraulic binder.
• the present invention relates to the use of a combination of several polycarboxylates, of different structures, but each having individually both a fluidizing effect and a retarding effect.
• the use of polycarboxylate (s) according to the present invention has proved particularly advantageous for fluidizing, and delaying the setting of the hydraulic binder for at least 90 minutes, especially 120 to 300 minutes, particularly 120 to 240 minutes.
• the setting time of a sulfoaluminous cement without setting retarder can vary between 10 and 60 minutes.
• the hydraulic binder as described above may comprise, in addition to the polycarboxylate polymer, at least one additional adjuvant chosen from air entraining agents, thickeners, adhesion and ductility agents, hardening accelerators, defoamers, dyes, or complementary retardants other than polycarboxylate.
• complementary retarders include carboxylic acids including tartaric acid and citric acid, carbohydrates including glucose; as an example of an air entrainer, surfactants, in particular glycol ethers, lauryl sulphates; as an example of thickener including cellulose derivatives and polyacrylamides; as an example adhesion and ductility agent including latex; as an example of a hardening accelerator, especially lithium and sodium carbonates; as an example of antifoam including polyethylene oxide copolymers polypropylene, triisobutylphosphates and fatty alcohols.
• the characteristics of the sulpho-aluminous cement used (industrial cement produced in Italy) are shown in Table 1. It contains 60% by weight of Yeelimite, 11% by weight of Belite and 23% by weight of anhydrite.
• the Portiand cement used here is an industrial CEM I. Its characteristics are shown in Table 2. Its composition is typical of a Portiand cement with a medium alkali content. Table 2 - Main characteristics of the Portiand cement used.
• the polycarboxylate used comes from AXIM France. It is a polycarboxylate with a grafting rate close to 20%. It is functionalized by long polyethylene glycol chains (about 5000 g / mol). Comparative adjuvant
• Citric acid is a retarding agent commonly used in Portiand, aluminous and sulfo-aluminous cements. Citric acid comes from Sigma-Aldrich. All the tests were carried out at 20 ° C. on cement pastes having a water / cement ratio (W / C) equal to 0.44. The pasta was obtained by mixing the water with the cement for 3 minutes using a Bioblock scientific propeller mixer.
• the evaluation of the initial setting time was carried out using a texturometric analyzer TA-XT2L This test consists of measuring a "penetration force" at a finite depth in a cement paste at a given time. A 7 mm 2 needle is pressed over a distance of 10 mm and the required applied force is measured.
• the setting time of the cement paste is deduced by considering that the beginning of setting takes place when the necessary force is 10 N, and that the end of setting occurs when the necessary force is 100 N.
• the spreading measurements were carried out on a dry glass plate placed on a horizontal plane.
• the formulation is mixed again at high speed (850 rpm) for 1 minute.
• the formulation is put in place in the mini-cone (1/5 of the Abrams cone, height 6 cm, high radius 1 cm, low radius 2 cm), vibrated and leveled.
• the cone is raised slowly and the measured spread (diameter).
• FIG. 1 represents the fluidizing effect induced by the polycarboxylate, at an implementation time of 15 minutes, on two types of cement: a Portland cement (results schematized by circles) and a sulpho-aluminous cement (squares).
• the polycarboxylate polymer actually has a fluidifying effect on the two cements, and that for a polymer dosage greater than 0.05% (by weight) relative to the cement (hydraulic binder), the fluidifying effect is approximately twice more important for a sulfo-aluminous cement than for a Portland cement.
• Table 3 shows the start times, expressed in minutes, of the cements Portland, and sulfo-aluminous studied.
• Citric acid a known retarder of Portland cement has a significant effect on Portland cement (+ 190 minutes) but relatively low on sulfo-aluminous cement (+ 15 minutes),

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)

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