WO1999047468A1

WO1999047468A1 - Water soluble or water dispersible dispersing agent for cement compositions and mineral particle aqueous suspension, and additives containing such dispersing agent

Info

Publication number: WO1999047468A1
Application number: PCT/FR1999/000655
Authority: WO
Inventors: Jean-Pierre Guicquero; Philippe Maitrasse; Martin Mosquet; Alphonse Sers
Original assignee: Lafarge S.A.
Priority date: 1998-03-19
Filing date: 1999-03-19
Publication date: 1999-09-23
Also published as: AU3038999A; FR2776285B1; FR2776285A1

Abstract

The invention concerns a water soluble or water dispersible dispersing agent for cement composition and mineral particle aqueous suspensions, containing carboxylic functions, optionally partially or totally salified and polyether chains It is obtained by partial esterification catalysed by introducing a base, and reacting: at least a polycarboxylic acid obtained by polymerising at least an unsaturated carboxylic acid, containing on average at least 6 carboxylic functions per molecule; and at least a polyether containing a free hydroxyl group capable of reacting with one carboxylic function of said polycarboxylic acid.

Description

- 1 -

Water-soluble or water-dispersible dispersant for cement compositions and aqueous suspensions of mineral particles, and adjuvants containing such a dispersant

The subject of the invention is a water-soluble or water-dispersible dispersant for cement compositions and aqueous suspensions of mineral particles. The invention also relates to adjuvants containing such a dispersant.

Dispersants, water-soluble or water-dispersible, for cement compositions, such as grouts, mortars and concretes, making it possible to reduce the water content with a high conservation of the workability (ie maintenance of the fluidity or low loss by sagging), are well known and used for many years. These water-soluble dispersants are sometimes referred to as water reducers or thinners, or plasticizers, or even superplasticizers. These water-soluble dispersants make it possible to obtain cement compositions with the desired consistency with reduced water contents and, consequently, an improvement in the mechanical strengths of the cured cement compositions. In recent years, water-soluble dispersants based on polycarboxylate, having the above characteristics, have been developed.

A water-soluble or water-dispersible dispersant has now been found which allows cement compositions with reduced water content to maintain prolonged fluidity, associated with high values of resistance, in particular high values of compression resistance at young ages, (that is to say 24 hours after the preparation of the cement compositions containing this dispersant).

More specifically, the water-soluble or water-dispersible dispersant according to the invention, suitable for cement compositions and aqueous suspensions of mineral particles, contains acid carboxylic functions, optionally partially or totally salified and polyether chains. This dispersant is characterized in that it is obtained by partial esterification catalyzed by the introduction of a base, by reacting:

- At least one polycarboxylic acid obtained by polymerizing at least one unsaturated carboxylic acid, containing on average at least six carboxylic functions per molecule;

- And at least one polyether containing a free hydroxyl group which can react with a carboxylic function of said polycarboxylic acid, preferably a terminal hydroxyl group.

SUBSTITUTE SHEET (RULE 26) A difference between the dispersant of the present invention and the known dispersants based on polycarboxylate lies in the fact that it is obtained by partial esterification catalyzed by the addition of a base.

This esterification makes it possible to prevent the polyether molecules from breaking, so that the weight-average molecular weight of the polyether before esterification is equal to that of the polyether chains of the dispersant according to the invention. In addition, it has been found that the dispersants according to the invention have the above-mentioned properties. In particular :

- They make it possible to prepare particularly homogeneous cement compositions (little or no segregation and little or no bleeding), these compositions being, moreover, flowable so as to be easy to install;

- they lead to compressive strengths at high young ages.

Preferably, the base used for the partial esterification is an alkali metal hydroxide, preferably sodium hydroxide or lithium hydroxide. As a base, a tertiary amine can also be used.

Advantageously, the partial esterification reaction is carried out in order to esterify 10 to 90% of the available carboxylic functions of the polycarboxylic acid. Very satisfactory performances (in terms of reduction of the water content, maintenance over time of the fluidity and mechanical resistance at young ages) were obtained with a dispersant in accordance with the invention of which 30 to 70% of the carboxylic functions have been esterified with a polyether or a mixture of polyethers. The best maintenance over time of the fluidity has been obtained when at least 50% of the carboxylic functions are esterified with a polyether or a mixture of polyethers.

The weight average molecular weight, "Mw", of the dispersant according to the invention, measured by liquid gel permeation chromatography, with polyethylene glycol calibration, generally varies from approximately 1000 to approximately 1,000,000, preferably approximately 10 000 to about 80,000. - 3 - Preferably, the polycarboxylic acid used to prepare the water-soluble dispersant according to the invention is obtained by polymerization of a monomer mixture containing as essential component acrylic acid and / or methacrylic acid (hereinafter called (meth) acrylic acid). Optionally, the polycarboxylic acid is also based on at least one comonomer with one or more ethylenic unsaturations which can be copolymerized with (meth) acrylic acid, such as an ester of (meth) acrylic acid, for example l methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, an alkylene glycol (meth) acrylate, a polyethylene glycol (meth) acrylate, etc. ; an unsaturated dicarboxylic acid, for example maleic acid, fumaric acid, itaconic acid, citraconic acid, etc., or a corresponding anhydride, or an ester of these unsaturated dicarboxylic acids; unsaturated amides, for example methacrylamide, etc. ; aromatic vinyls, for example styrene, etc. ; unsaturated sulfonates, for example vinyl sulfonates and their salts, etc. ; monomers with double ethylenic unsaturation in small proportion, preferably at most 5% by weight, for example divinylbenzene, or a mixture of the above-mentioned comonomers.

This polycarboxylic acid is, more preferably, a homopolymer of acrylic acid or a copolymer of acrylic acid and methacrylic acid.

The weight average molecular weight of the polycarboxylic acid preferably ranges from 500 to 60,000.

The polycarboxylic acid to be esterified is preferably in the form of an aqueous solution miscible with the polyether (s) or in the form of a solid soluble in the polyether (s).

According to an advantageous variant, the polyether containing a free hydroxyl group, used to prepare the dispersant according to the invention, is a polyalkylene glycol alkyl ether, preferably a mixture of polyalkylene glycol alkyl ethers of formula X- (OY) n-OH in which :

- X represents an alkyl group of 1 to 8 carbon atoms, preferably from 1 to 4 carbon atoms, even better, X is a methyl radical; - 4 -

- Y represents an alkylene group of 2 to 4 carbon atoms or a mixture of these alkylene groups;

- n is an integer varying from 3 to 500;

the polyalkylene glycol alkyl ether or the mixture of polyalkylene glycol alkyl ethers is such that the average molar ratio of the oxyethylene units to the oxyalkylene units (YO) varies from approximately 0.5 to 1, even better from 0.7 to 1. Thus, subject to respecting the above conditions, a mixture of polyalkylene glycol alkyl ethers may contain one or more polyalkylene glycol alkyl ethers of formula X- (OY) n-OH in which Y is not ethylene.

Preferably, the polyether consists of: a polyethylene glycol alkyl ether, optionally containing oxypropylene units, - or, several polyethylene glycol alkyl ethers, optionally containing oxypropylene units, of average molecular weight at different weight, and, optionally, one or more polypropylene glycol alkyl ethers, of average molecular weight to different weight, which may contain oxyethylene units, provided that the average molar ratio of the total of the oxyethylene units to the total of the oxyalkylene units varies from approximately 0.5 to 1, even better, from 0.7 to 1.

Particularly satisfactory results have been achieved with dispersants according to the invention obtained from at least one polycarboxylic acid containing on average at least 6 carboxylic functions per molecule and at least one polyether containing a free hydroxyl group, chosen from:

- A polyethylene glycol methyl ether (in the above formula, X is a methyl radical, Y is an ethylene group) containing on the order of 10 to 150 oxyethylene units (n varies from approximately 10 to approximately 150); - Or a mixture of polyethylene glycol methyl ethers which are essentially differentiated by the length of their chain of oxyethylene units, this mixture containing, on average per molecule, of the order of 5 to 50 oxyethylene units. - 5 -

In addition to the polyalkylene glycol alkyl ether (s), one or more polyethers bearing at least two free hydroxyl groups may be provided in the reaction medium, in a limited quantity.

Also, one can provide, in limited quantity, a polyalkylene glycol or a mixture of polyalkylene glycols comprising an alkyl, aryl or alkyl aryl chain, branched or not, of 8 to 22 carbon atoms. The amount of these polyalkylene glycols is preferably less than 2 mol%, based on the number of carboxylic functions of the polycarboxylic acid.

The dispersant according to the invention can be used with compositions based on hydraulic cement such as Portland cements; aluminous cements; various composite cements (CM2 OR CM3) formed by mixing, before or after grinding, Portland clinker and slag, natural pozzolans and / or fly ash; or hydraulic materials other than cement, such as hydraulic calcium sulfates, binders containing CSAs (calcium sulfo-aluminate), hydraulic glasses, magnesium and phosphate binders.

The dispersant according to the invention gives excellent performance even when used in small quantities, generally from 0.05% to 1.5%, preferably from 0.08% to 1% by dry weight relative to the weight cement.

The dispersant according to the invention can be added to aqueous suspensions of mineral fillers without hydraulic setting, as a fluidizer. Thus, the dispersant according to the invention is suitable for aqueous suspensions of mineral fillers such as, for example, calcium fillers such as calcium carbonate, slaked lime or calcium fluoride; mineral oxides such as titanium dioxide; ferric oxide, chromium oxide, silica or aluminas; or other fillers such as silicates such as mica, etc.

The dispersant according to the invention is advantageously obtained by adding a base in an aqueous reaction medium and by reacting, at a temperature between 160 and 200 ° C: - 6 -

- At least one polycarboxylic acid obtained by polymerization of at least one unsaturated carboxylic acid, containing on average at least 6 carboxylic functions per molecule;

- And at least one polyether containing a free hydroxyl group which can react with a carboxylic function of said polycarboxylic acid.

In the case where the polyether consists of several polyalkylene glycol alkyl ethers which are essentially differentiated by their weight average molecular weight, it may be advantageous to conduct the esterification reaction by successively adding the polyalkylene glycol alkyl ethers, starting with those with the highest weight average molecular weight (which are less reactive) and ending with the lowest weight average molecular weight (which are the most reactive). This results in a significant gain in the total time for carrying out the esterification.

When the base is lithium hydroxide, it is preferable to add to the reaction medium at least 0.04 mol% of LiOH, H2θ, this percentage being related to the number of carboxylic functions of the polycarboxylic acid. More preferably, the amount of lithium hydroxide will be at most equal to 10 mol% relative to the number of carboxylic functions of the polycarboxylic acid.

In addition, the partial esterification reaction is preferably carried out under reduced pressure in order to gradually remove the water formed during the esterification reaction. The reduced pressure is generally between about 133 Pa and about 13340 Pa (1-100 mmHg).

The esterification reaction is stopped as soon as the target percentage of esterified carboxylic functions of the polycarboxylic acid is reached.

For the sake of clarity, in the following description, the dispersant according to the invention, which has just been described in detail, will be called "dispersant (Dl)".

The dispersant (D1) can be used in combination with other known additives such as, for example, another dispersant, a thickener, an anti-foaming agent, a water repellent, a retarder or accelerator for hardening. The present invention also relates to adjuvants containing the dispersant (Dl).

A first adjuvant (A1) consists of a combination of dispersing agents, characterized in that it consists of at least one dispersant (Dl) and at least one dispersant (D2), water-soluble or water-dispersible, comprising at least one amino-alkylene phosphonic group, optionally salified, and at least one polyoxyalkylated chain, and corresponding to the formula:

/ P [R-0 (R_-0) n] _{r + q} [Q (-N ^) y]

A-PO3H2

in which :

. R is a hydrogen atom or a saturated or unsaturated monovalent hydrocarbon group containing from 1 to 18 carbon atoms and optionally one or more heteroatoms;

. the Ri's are similar or different from each other and represent an alkylene such as ethylene, propylene, butylene, amylene, octylene or cyclohexene, or an arylene such as styrene or methylstyrene; the Ra may contain one or more heteroatoms;

. Q is a hydrocarbon group having from 2 to 18 carbon atoms and optionally one or more heteroatoms; . A is an alkylidene group having from 1 to 5 carbon atoms; . the Rj are similar or different from each other and can be chosen from:

the alkyl group comprising from 1 to 18 inclusive carbon atoms and which can carry groups [R-0 (Rι-0) n, R and Ri having the abovementioned meanings,

* and the group y Rk

-B-N.

A-PO3H2

- Rk designating a group such as Rj,

- B denoting an alkylene group comprising from 2 to 18 carbon atoms, - 8 -

"n" is a number greater than 0,

"r" is the number of groups [R-0 (Rι-0) n] carried by all of the Rj,

"q" is the number of groups [R-0 (R_-0) n] carried by, the sum "r + q" is between 1 and 10,

"y" is an integer between 1 and 3,

Q, N and the Rs can together form one or more cycles, this or these cycles possibly also containing one or more other heteroatoms.

Preferably, the dispersant (D2), combined with the dispersant (Dl) in the aforementioned first adjuvant (Al), corresponds to the formula:

[R-0 (R-0) n] _q [Q (-N ^) y]

A-PO3H2 in which:. R is a hydrogen atom or a monovalent hydrocarbon group, saturated or unsaturated, having from 1 to 8 carbon atoms and, optionally, one or more heteroatoms; . Ri represents ethylene or propylene or a mixture of ethylene and propylene. Preferably, 60 to 100% of the Ri are ethylene groups; . Q is a hydrocarbon group having 2 to 8 carbon atoms and, optionally, one or more heteroatoms; . A is the methylene group;

. the Rj are similar or different from each other and can be chosen from: * the group CH2-PO3H2, * and the group

^ / - R -B-N

\ cH2-PO3H2 - Rk denoting a phosphonic group such as Rj, - B denoting an alkylene group comprising from 2 to 4 carbon atoms,. "n" is an integer between 10 and 250,. "q" is an integer equal to 1 or 2,. "y" is an integer equal to 1 or 2. - 9 -

A detailed description of the dispersant (D2) (in particular the preparation conditions) is given in European patent n ° 0663892.

The weight ratio of the dispersant (Dl) to the dispersant (D2) can vary within wide limits: from 1/99 to 99/1. The combination of dispersants (Dl) and (D2) makes it possible to prepare cement compositions and aqueous suspensions of mineral particles at the desired fluidity with reduced water contents. In addition, by varying the proportion of the dispersant (Dl) on the dispersant (D2), it is possible to modulate the maintenance of the fluidity over time of the cement compositions, in particular of the cement compositions based on compound cement (CM2 or CM3).

A second adjuvant (A2), containing the dispersant (Dl) is characterized in that it is in the form of a uniform mixture comprising:

- some water ; - at least one non-water-soluble or water-dispersible antifoaming agent, optionally in combination with at least one aforementioned dispersant (D2);

- at least one organic compound (C) containing:

- at least one primary, secondary or tertiary amine function, optionally partially or totally neutralized by a Brônsted acid, organic or mineral;

- And at least one alkyl or alkyl-aryl chain, linear or branched, saturated or unsaturated, comprising at least 8 carbon atoms, and optionally heteroatoms, chosen from oxygen, sulfur or nitrogen;

- at least one mineral stabilizer when the pH of said mixture is greater than 7; - optionally, an acid or a base to adjust the pH of said mixture.

In the adjuvant (A2):

- "non-water-soluble or weakly water-soluble defoaming agent" means a weakly or non-soluble defoaming agent in aqueous media at room temperature (about 20 ° C) and at atmospheric pressure;

- "uniform mixture" means a mixture which, left to stand, can range from a clear mixture (such as a microemulsion) to a cloudy mixture (such as an oil-in-water emulsion). Sometimes a thin film, Generally, foam may be present on the surface of the uniform mixture.

Thanks to the adjuvant (A2), the following results have been achieved: - the adjuvant (A2) has, for a wide variety of defoaming agents with little or no water-soluble properties and a wide variety of water-soluble or water-dispersible additives, better storage stability compared to a control free from the organic compound (C) described above. Indeed, the adjuvant (A2) remains a uniform mixture for at least 24 hours; - the adjuvant (A2) can be sold in the form of a ready-to-use packaging, more or less concentrated, to be diluted if necessary before use.

Advantageously, the dry extract of the adjuvant (A2) varies between approximately 5% by weight and approximately 80% by weight, preferably between approximately 10% by weight and approximately 70% by weight, even better between approximately 20% by weight and about

60% by weight.

- the adjuvant (A2) is dispersible in aqueous suspensions of mineral particles and mixtures based on hydraulic binder, and the anti-foaming agent which it contains can then effectively act to reduce the volume of entrained air.

The pH of the adjuvant (A2) can be acidic (less than 7) or basic (greater than 7).

When its pH is basic, the adjuvant (A2) necessarily includes at least one mineral stabilizer which contributes to keeping the mixture uniform. On the other hand, when the pH of the adjuvant (A2) is acidic, the addition of a mineral stabilizer is not essential.

The particle size of the mineral stabilizer, which consists of finely divided grains, is preferably such that at least 90% of the grains pass through a square mesh sieve with 50 μm side, more preferably with 10 μm side.

Preferably, the mineral stabilizer has an ability to develop an additional viscosity under the effect of a shear gradient and in the presence - 11 - water, for example when using ball mills or high speed mixers fitted with deflocculating blades. By way of example of a mineral stabilizer, mention may be made of clays, such as sepiolite, bentonite or a mixture of these types of clays. The best results have been obtained with sepiolite.

Advantageously, the sepiolite is used at a rate of 0.5% to 2.5% by weight relative to the total wet weight of the adjuvant (A2).

When the adjuvant (A2) is free from mineral stabilizers, the pH of the adjuvant (A2) must be acidic (less than 7), preferably less than or equal to 6, even better between 2 and 6 (inclusive). Indeed, at a pH greater than or equal to 7, in the absence of a mineral stabilizer, the stability and, consequently, the homogeneity of the adjuvant (A2) disappear: the uniform mixture most often becomes unstable, c that is to say a separation of the organic and aqueous phases is noted.

One of the essential constituents of the adjuvant (A2) according to the invention is an organic compound (C) containing at least one primary, secondary or tertiary amine function, optionally partially or totally neutralized by a Brônsted acid, and at least a linear or branched, saturated or unsaturated alkyl or alkyl-aryl chain, this chain comprising at least 8 carbon atoms, preferably at least 12 carbon atoms, and optionally heteroatoms chosen from oxygen, sulfur or nitrogen: in the following description, it will be designated simply by the term "organic compound (C)".

The organic compound (C) has been found to maintain the uniformity of the adjuvant (A2) for 24 hours or more. The organic compound (C) therefore constitutes the organic stabilizer of the adjuvant (A2).

The adjuvant (A2) can contain, as organic stabilizer, several organic compounds (C) of different chemical nature.

In accordance with a preferred variant of the invention, the formula of the organic compound (C) is: - 12 -

R R4

^ - N Rô - ^ y ^y JH Rδ Rs Rs ^

in which :

- R4 is an alkyl or alkyl-aryl chain, linear or branched, saturated or unsaturated, containing at least 8 carbon atoms, preferably at least 12 carbon atoms, even better at most 22 carbon atoms.

Optionally, R4 can comprise one or more heteroatoms chosen from oxygen, nitrogen or sulfur to form functional groups such as ether or thioether groups or alcohol or thioalcohol groups; - Rs is a hydrogen atom, or a chain of R7-O oxyalkylene units where the R7 are similar or different from each other and represent an alkylene such as ethylene, propylene or butylene, this chain of R7-O oxyalkylene units having in the terminal position a hydrogen atom or an alkyl or alkyl-aryl group; - Re is a hydrogen atom or a radical independently chosen from the above definitions for R4 and Rs;

the total number of units (R7-O) which may be present in Rs and Rβ, when R7 is ethylene, is preferably at most equal to 12, more preferably still at most equal to 8.

The total number of units (R7-O) when R7 is propylene or butylene is not critical. However, the total number of such patterns will preferably be at most equal to 5.

Preferably, the number of functional nitrogen groups in the organic compound (C) is at most equal to 2.

The preferred organic compounds (C), with which very satisfactory results have been obtained, are the oleic amine and oleic amine derivatives, optionally containing units (R7-O) according to the definitions and conditions mentioned in the - 13 - present description. This oleic amine is optionally mixed with other organic compounds (C) of different chemical nature. The best results have been obtained with the following amines, protonated or not: oleic amine, coconut amine and tallow amine, each of these amines having one mole of ethylene oxide; the oleic amine containing five moles of ethylene oxide; N, N-bis (2 hydroxyethyl) oleylamine (or oleic amine containing two moles of ethylene oxide). Satisfactory results have also been obtained with the following amines, whether protonated or not: the tallow amine with five moles of ethylene oxide, the tallow amine with seven moles of ethylene oxide, the amine copra to two moles of ethylene oxide.

As indicated above, the organic compound (A) can comprise two nitrogen functional groups and thus belong to the family of diamines. By way of example, there may be mentioned N, N ', N'-tri (2-hydroxyethyl) N-tallow-propylene diamine.

In the adjuvant (A2), in combination with the dispersant (Dl), one or more water-soluble or water-dispersible additives chosen from dispersants (D2) may be provided, agents making it possible to reduce the amount of mixing water, dispersants , plasticizers, plasticizers, mass water repellents, retarders or accelerators for setting or hardening or a mixture of the aforementioned additives.

Among the non-water-soluble or weakly water-soluble defoaming agents suitable for the adjuvant (A2), there may be mentioned mineral oils, phosphoric esters, ethylene oxide / propylene oxide copolymers and alkylpolyalkoxyesters. Preferably, the defoaming agents selected are those which are miscible with the organic compounds (C) described above, that is to say those which can lead to a homogeneous mixture with one of these organic compounds (C). More preferably, they are chosen from the family of phosphoric esters.

The mass quantity of organic compound (C) to be provided depends on the composition of the adjuvant (A2). Preferably, a mass ratio of organic compound (C) / antifoaming agent of between approximately 0.01 and approximately 5 is used. - 14 - Generally, an excess of organic compound (C) relative to the amount necessary for the stability of the adjuvant (A2) is not desirable first of all for reasons of cost of the formulation, and also in because of the volume of air which can be entrained in the case where this organic compound (C) has an emulsifying power even in a neutral pH environment (equal to 7) or basic.

The mass ratio of anti-foaming agent / dispersant (Dl, optionally combined with another water-soluble or water-dispersible additive) is generally between approximately 0.002 and approximately 0.5, preferably between approximately 0.005 and approximately 0.1.

The adjuvant (A2) may optionally contain other compounds, provided that they do not appreciably affect the stability of the emulsion. These optional compounds are preferably water-soluble and are, for example, air entrainers.

Preferably, the adjuvant (A2) is prepared in concentrated form, as follows: is introduced into a dispersing device adapted to the consistency of the adjuvant (A2) and making it possible to avoid excess air entrainment , the concentrated aqueous solution containing the dispersant Dl and optionally at least one other water-soluble or water-dispersible additive, this concentrated solution is brought to a temperature of the order of 60-80 ° C., then the anti-foaming agent, the organic compound, is added (C) and, if necessary, a mineral stabilizer and / or a Bronsted acid. If necessary, this adjuvant (A2) is diluted with water in concentrated form. Also, if necessary, the pH of the adjuvant (A2) is adjusted by means of an acid or a base.

The invention finally relates to the use:

- a dispersant (Dl), water-soluble or water-dispersible, according to the invention, optionally in combination with other additives; - or, an adjuvant (Al) consisting of a combination of dispersants (Dl) and

(D2), described above,

- or of an adjuvant (A2) containing at least one dispersant (Dl), water-soluble or water-dispersible, according to the invention, described above, - 15 - to fluidify and improve the homogeneity and workability of cement compositions with reduced water content or of an aqueous suspension of mineral particles.

In the following examples, other advantages and variants of the invention are described.

Example 1

Preparation of a dispersant by partial esterification of a polyacrylic acid with a monofunctional polyethylene glycol methyl ether.

Raw materials used

- 120 g of polyacrylic acid sold by BASF under the name Sokalan CP10S. Its weight average molecular weight is equal to 4000 Daltons. It is diluted to 50% in water;

- 252 g of a polyethylene glycol methyl ether (type M750 from Hoechst) of average molecular weight by weight equal to 750 Daltons;

- 0.60 g of lithium hydroxide.

Dispersant preparation

The abovementioned raw materials are introduced into an enamelled reactor, equipped with stirring, a distillation device and a partial vacuum system, in the following order:

- polyacrylic acid; - lithium hydroxide;

- polyethylene glycol methyl ether (liquid product at 50 ° C).

At the end of the introduction of the polyethylene glycol methyl ether, the reactor is placed under partial vacuum (20 to 30 mm Hg) with a nitrogen blanket. Then, heating, around 60 ~ 75 ° C: we get the start of distillation of the water supplied with polyacrylic acid. Then the temperature is raised to 165 ~ 175 ° C to esterify. During the esterification reaction, the water formed is removed. After 6 hours at 165 ~ 175 ° C, the progress of the reaction is checked by an index analysis - 16 - acid and liquid chromatography control by gel permeation (GPC) with polyethylene glycol (PEG) calibration.

If the results of these analyzes are not satisfactory, the esterification is continued, until the desired physicochemical characteristics are obtained: in this example, the acid number targeted at the end of the reaction is equal to 56 mg KOH / g ( this corresponds to an esterification of 46% of the carboxylic functions of the starting polyacrylic acid).

If the results of these analyzes are consistent, the reaction is stopped. To do this, the reactor is cooled to a temperature of the order of 80 ° C. and then 4 g of oleic amine are added to 2 moles of ethylene oxide (sold under the name Noramox 02 by CECA) and 4 g tributylphosphate (antifoam). Finally, the product is diluted with water to obtain a dry extract of 30% and it is neutralized with sodium hydroxide at pH: 6.9. The dispersant thus prepared is ready for use.

Performances

The ready-to-use dispersant, with 30% dry extract, is evaluated through measurements of workability and measurements of mechanical resistance in compression.

To do this, a concrete is prepared comprising, in kg per m ³ of concrete:

- crushed gravel 12.5 / 20 mm: 474

- crushed gravel 8 / 12.5 mm: 352

- crushed gravel 4/8 mm: 189 - sand 2/4 mm: 135

- 1/4 mm sand: 127

- sand 0.5 / 1 mm: 79

- sand 0.375 / 1 mm: 166

- sand 0 / 0.375 mm: 234 - sand 0 / 0.160 mm: 51

- CPA HP cement from Cormeilles: 350

- x% by weight of the ready-to-use dispersant (0 30% dry extract) based on the quantity of cement;

- water: 185 - 17

The concrete obtained is homogeneous: there is no phenomenon of segregation or bleeding. In addition, it is easy to work and set up.

Maintaining the fluidity of the concrete was evaluated by measuring the fluidity over time (measurement of the "slump") under the conditions of standard P NF EN-12 382, at tO (just after preparation of the concrete) and then 30 minutes after tO, 60 minutes after tO and 90 minutes after tO.

The compressive strength was measured according to standard P NF EN-12 394.

The results obtained are grouped in the following tables (I) and (II):

Table (I) - Measurement of ouyrabilities

Dosing of the SLUMP E / C% entrained dispersing air x (in cm) (*)

(in% by weight)

T0 T0 + TO + 60 TO + 90 T0 TO + 90 30 min. min. min. min.

0.8 0.52 23 23 22 20 1.5 1.9

0.53 0.52 19 17 11 2.6 2.7

(*) this percentage corresponds to the volume of air entrained over the total volume of concrete. The entrained air is measured using a concrete aerometer according to the air entrainment standard P NF 18353.

Table (II) - Compressive strengths (Rc) at 20 ° C (expressed in MPa - Measurement accuracy 1%)

Dosage of Rc Rc Rc dispersant x at 24 hours to 7 days to 28 days (% by weight)

0.8 16.7 31.2 41.5

0.53 19.4 35.3 38.9

18

Examples 2 to 6

Preparation and evaluation of additives (A) consisting of a combination of dispersants (Dl) and (D2) in concrete.

The dispersant (Dl) is obtained by reproducing the majority of the operating conditions set out in Example 1 to prepare the dispersant ready for use, with the exception of the dilution operation with water which is carried out so as to obtain a dry extract of 40%.

The dispersant (D2) is the product sold under the name OPTIMA 100 by the company CHRYSO. This product contains a fluidizing compound containing at least one amino-alkylene phosphonic group and at least one polyoxyalkylated chain and has a dry extract equal to 30%.

In Examples 3 to 5, combinations of dispersants (Dl) and (D2) are evaluated on concrete by varying the proportion by weight of the quantity of dispersant (Dl) to the quantity of dispersant (D2), compared with the dispersant ( Dl) alone (example 2) and dispersant (D2) alone (example 6).

Dry extract of the dispersant or

Examples proportion of (Dl) to (D2) of the mixture of dispersants

(in% by weight)

2 100/0 40%

3 90/10 30%

4 75/25 30%

5 60/40 30%

6 0/100 30%

The measurements of workability, air entrainment and mechanical resistance in compression were carried out with the concrete formula indicated in Example 1 and with:

- 0.67% by wet weight of the dispersant (Dl) in Example 2, or

- 0.8% by wet weight of one of the combinations of the dispersants (Dl) and (D2) indicated for Examples 3 to 5, or of the dispersant (D2) in Example 6. - 19

The results obtained are collated in Tables (III) and (IV).

Table (III) - Measurement of breathability

Ex. W / C Workability% entrained air

TO T0 + T0 + T0 +, T0 T0 + 30 min. 60 mins. 90 mins. 60 mins.

2 0.44 21 16 4 - 2.1 2.5

3 0.54 21 23 23 21 2.1 2.4

4 0.54 22 23 23 21 1.9 2.2

5 0.54 22 23 22 20 1.9 2.4

6 0.57 20 20 20 20 2.1 2.5

Table IV - Compressive strengths (Rc) at 20 ° C (expressed in MPa)

Examples Rc Rc Rc at 24 hours to 7 days to 28 days

2 30.4 48.5 55.5

3 17.7 32.4 37.1

4 17.4 31.3 36.9

5 17.1 31.3 36.6

6 13.3 28.8 35.2

The concretes of examples 2 to 6 are runny, easy to set up and have little bleeding. In addition, the addition of the dispersant (D2) in the dispersant (Dl) makes it possible to achieve a significant maintenance of the workability.

Compared to the dispersant (D2) alone, the combinations of the dispersants (Dl) and (D2) lead to a greater reduction in water, to greater resistance at 24 hours and to slightly higher long-term resistance. • 20 -

EXAMPLES 7 TO 11

Preparation and evaluation of adjuvants (Al) consisting of a combination of dispersants (Dl) and (D2) in grouts.

The dispersant (Dl) described in Examples 2 to 6 is used. The dispersant (D2) is the product sold under the name OPTIMA 100 by the company CHRYSO.

In Examples 8 to 10, the fluidity of a grout containing a combination of dispersants (Dl) and (D2) is measured, by varying the proportion by weight of dispersant (Dl) on the dispersant (D2), compared with a grout containing only the dispersant (D1) (example 7) and a grout containing only the dispersant (D2) (example 11).

Examples proportion of dry extract of the dispersant or (Dl) on (D2) of the mixture of dispersants

(in% by weight)

7 100/0 40%

8 80/20 40%

9 50/50 40%

10 20/80 40%

11 0/100 30%

The grout is prepared by mixing in a kneader, at room temperature, the water (at around 20 ° C), the dispersant or the mixture of dispersants, and the cement (this is CPA cement 52.5 R from Val of Azergues).

The water to cement ratio (W / C) of the grout is equal to 0.32 and the amount of dispersant introduced into the grouts of Examples 7 to 10 is equal to 0.7% by weight (wet), based on the amount of cement, in Example 11, and is equal to 1.25% by weight (wet) based on the amount of cement.

The grouts obtained are homogeneous and self-leveling in the case of Examples 8 to 11.

The fluidity of the grouts was evaluated using the Marsh cone: it is a frustoconical mold with a volume equal to 1.6 liters, with two openings, the lower opening of - 21 - smaller diameter is provided with a cylindrical nozzle 50 mm high and 10 mm in diameter. The conditions for measuring the fluidity are as follows: after humidification of the Marsh cone and closure of the outlet of the Marsh cone, at the level of the nozzle. Pour the grout into the Marsh cone up to the mark corresponding to a volume of 1 Liter. The flow time of the grout through the nozzle is then measured from a time (t) corresponding to the time (tO) of filling the cone plus the time for keeping the grout in the cone.

In addition, the start to set (D.P.), end to set (F.P.) and set (TPS.P.) times were measured on each grout placed in a frustoconical cup. After having leveled the surface of the cup filled with grout, the cup is placed in an automatic prisometer equipped with a needle and a movable part in accordance with standard NF P-15414. This test then involves dropping the needle into the cup.

We consider that:

- the start of the setting is made as soon as the insertion of the needle is stopped at least 2.5 mm from the bottom of the cup;

- the end of the setting is carried out at the end of the time when the needle does not penetrate, for the first time, more than 2.5 mm below the level surface of the cup.

The results obtained are shown in Table V below:

Ex. Flow time Setting time in minutes in hours and minutes

T0 T = 30 T = 1 h T = 2 h T = 3 h T = 4 h D.P. F.P. TPS. min. P.

7, 11 13.5 20,, n.m. n.m. n.m.

8 24 10 10 10.7 π, ι 12.6 12:43 7:05 p.m. 6:22 a.m.

9 20 11 10 10.5 10.6 11.6 12:25 6:55 p.m. 6:30 a.m.

10 14 10.2 10 9.5 10 10.5 5:23 p.m. 9:45 p.m. 4:22 a.m.

11 12.5 10.2 14.2 13.8 13.1 13.2 nmnmnmnm means not measured - 22 -

Example 12

Evaluation of the dispersant (Dl) of Example 2 in a concrete composition for prefabrication.

To do this, a concrete is prepared comprising, in kg per m ³ of concrete:

- crushed gravel 12.5 / 20 mm: 380

- crushed gravel 8 / 12.5 mm: 280

- crushed gravel 4/8 mm: 420 - sand 2/4 mm: 57

- 1/4 mm sand: 250

- sand 0.5 / 1 mm: 130 - sand 0.315 / 1 mm: 200 - sand 0 / 0.315 mm: 100 - sand 0 / 0.160 mm: 80

- CPA HP Cormeilles cement: 400

- 0.25% by dry weight of the dispersant (Dl) based on the amount of cement

- water: 180

This concrete is poured into 14 cm side cubic molds and baking is carried out under the following conditions: 1 hour at 40 ° C, temperature rise from 40 ° C to 80 ° C in 1 hour 30 min. 80 ° C for 2 hours, finally decrease the temperature from 80 ° C to 40 ° C in 1 hour 30 min.

The compressive strength of hardened concrete was measured under the conditions of standard P NF EN-12394 after a time (t) counted from the pouring of the concrete into the cubic mold. The results are collated in Table VI below:

Example Compressive strength (in MPa) after

6 hours 24 hours 7 days 28 days

Example 12 36.2 44.5 63.3 69.9

- 23 - Examples 13 to 24 Procedure for the preparation of the dispersants of Examples 13 to 22.

Raw materials used. - A 30% dispersion in water of polyacrylic acid obtained by polymerization of x moles of acrylic acid and 1 mole of thioglycolic acid; - one (or more) polyethylene glycol methyl ether comprising on average, y ether functions; - 1% by mole of sodium hydroxide per carboxylic function of polyacrylic acid.

Dispersant preparation

In a reactor equipped with agitation, a distillation device and a partial vacuum system, sufficient quantities of the abovementioned raw materials are introduced, depending on the desired esterification rate. The reactor is placed under partial vacuum (20 to 30 mmHg). Then the temperature of the reaction medium is raised to distill off the water supplied with the polyacrylic acid. Then the temperature is raised to about 175 ° C to carry out the esterification reaction. The duration of the esterification reaction is of the order of 5 hours.

After esterification, the reaction medium which contains the esterified polyacrylic acid is used as it is as a dispersant.

Evaluation

The dispersants were evaluated by spreading measurements of cement pastes containing CPA HTS Le Teil cement, the dispersant and the mixing water (the W / C ratio is equal to 0.26). The cement pastes are prepared manually and the dispersant is introduced into the mixing water.

For the evaluation of this paste, the cement paste is introduced into a cylinder with a diameter equal to 51 mm and a height equal to 32 mm, the lower end of which has been closed. After filling the cylinder, we release the lower end and measure • 24. the diameter of the wafer obtained, along 3 axes, after stabilization. At the lowest spreading values, the diameter of the wafers is obtained with an accuracy of plus or minus 1 mm, and a precision of plus or minus 2 mm from 220 mm in diameter.

The value given in the table below is the average of the values measured along 3 axes.

Other structural characteristics of the dispersants as well as the results obtained are given in the table below:

Ex. Characteristics Initial spreads (in dispersant mm) as a function of the dispersant dosage x y Esterification rate 0.3% 0.1% cation (a) (b) (b)

13 19 17 32% 258 204

14 34 17 30% 253 158

15 34 17 37% 237 146

16 9 17 30% 251,159

17 19 17 40% - 206

18 19 17 50% - 156

19 19 11 28% - 172

20 19 11 40% - 183

21 19 8 30% - 186

22 19 8 38% - 184

23 (*) - - - 224 58

24 (*) - - - 201 65

(a) the esterification rate is related to the total number of carboxylic functions of the polyacrylic acid concerned.

(b) these dosages are expressed by weight of dry dispersant over the weight of cement.

(*) Examples 23 and 24 are comparative examples. In Example 23, the dispersant used is the GT resin sold by the company CHRYSO. It is a melamine-based polysulfonate. In Example 24, it is a 30% diphosphonated dispersant in water, of formula: - 25 -

-CH ₂ Pθ3HNa

CH3 - O - (CH2-CH2-O) 2o - CH2 - CH - N

CH3 CH ₂ Pθ3HNa

Examples 25 to 37

The procedure used for the preparation of the dispersants of Examples 25 to 36 is identical to that indicated for the dispersants of Examples 13 to 22. The dispersant used in Example 37 corresponds to the dispersant described in Example 1.

The dispersants of Examples 25 to 37 were evaluated on cement paste under the conditions set out for Examples 13 to 24, with the following differences: the cement pastes are prepared with CPA HP cement from Cormeilles with a water ratio on cement (W / C) equal to 0.36 and a dispersant dosage equal to 0.24%, expressed as dry dispersant relative to the weight of cement.

The other structural characteristics of the dispersants as well as the results obtained are given in the table below.

Ex. Characteristics of the tal .talemen t (in mm) dispersing after handling the dough for a time t in min. 1 in cylinder x y Rate 0 min. 30 60 90 120 150 esterification min. min. min. min. min.

25 9 17 30% 167 126 89 77 - -

26 19 17 32% 191 164 94 75 - -

27 29 17 28% 201 209 116 77 - -

28 19 17 50% 168 222 230 230 219 195

29 29 17 49% 183 227 236 229 - -

30 29 17 59% 126 213 225 221 195 -

31 34 17 37% 198 205 130 - - -

32 34 17 50% 196 241 241 233 215 -

33 34 17 55% 182 239 229 223 214 -

34 19 17 34% 189 231 227 194 - -

35 19 11 44% 175 227 162 112 - -

36 19 8 38% 155 132 85 64 - -

37 - - - 124 212 214 216 - - 26 -

Examples 38 to 42

The procedure used for the preparation of the dispersants of Examples 38 to 42 is identical to that indicated for the dispersants of Examples 13 to 22, the only difference lies in the fact that in Examples 38 to 41, a mixture of two methyl ethers is used. of polyethylene glycol having respectively (yl) and (y 2) ether functions and each leading respectively to an esterification rate (tel) and (te2), expressed in% relative to the number of carboxylic functions of the starting polyacrylic acid.

The other structural characteristics of the dispersants and the results obtained are given in the table below.

The dispersants of Examples 38 to 42 were evaluated by means of spreading measurements, with cement pastes identical to those of Examples 25 to 37 and under the same conditions.

Ex Characteristics of the dispersant Spreadings (in mm) after holding the dough in the cylinder for a time t (in min.) X yl such y2 te2 0 min. 30 min. 60 mins. 90 mins.

38 19 17 30 3 20 191 240 251 252

39 34 17 20 3 30 247 247 248 217

40 39 17 30 3 20 234 245 245 233

41 59 17 30 3 20 224 235 233 192

42 34 17 50 0 0 196 241 241 233

Examples 43 to 53 The procedure used to prepare the dispersants of Examples 43 to 52 is indicated in Examples 13 to 22 and 38 to 42. The dispersants of Examples 43 to 53 are evaluated by means of spreading measurement (see conditions in examples 13 to 24) in aluminous cement pastes containing:

- cement of the commercial brand "FONDU" from the LAFARGE group; - water, in a water to cement ratio equal to 0.22;

- the dispersant at a rate of 0.2% by dry weight based on the weight of cement. • 27 -

The mixing time lasts 1.5 minutes. The other structural characteristics of the dispersants and the results obtained are given in the table below.

Ex. Dispersant characteristics Initial spreads (in mm) x yl such y2 te2

43 19 45 32 0 0 223

44 19 45 34 0 0 220

45 19 12 17 0 0 217

46 19 17 30 3 20 213

47 (*) 34 17 20 3 30 213

48 (*) 19 17 51 0 0 211

49 29 17 29 0 0 207

50 59 17 30 3 20 207

51 (*) 29 17 60 0 0 205

52 19 17 30 0 0 201

53 (**) - - - - - 200

(*) the pH of these dispersants was brought to pH 7 by addition of sodium hydroxide

(**) the dispersant used in Example 53 is the diphosphonated dispersant used in Example 24.

Examples 54 to 56 Evaluation of Dispersant Prepared from a Polymethacrylic Acid

The procedure used to prepare the dispersants of Examples 54 to 56 is identical to that indicated for the dispersants of Examples 38 to 42, the only difference being that, in these examples, acrylic acid is replaced by acid. methacrylic.

The dispersants are tested on micro mortar compositions with a water to cement ratio of 0.5. The composition of the micro mortars is as follows: 51.3 g of siliceous aggregate of diameter 0-0.160 mm and 234.3 g of siliceous aggregate of diameter 0-0.315 mm are pre-wetted with 68 g of water, with gentle stirring for one minute and left to stand for 5 minutes. 350 g of CPA CEM I cement from the Cormeilles plant - 28 - are then added with gentle stirring. The dispersants dosed at 0.124% (percentage counted as a dry dispersant relative to the cement) and diluted in 107 g of water are then introduced and the mixture is kneaded for 1 minute at 3500 rpm.

Between measurements, the micro mortars are kept under stirring in a 1 liter bottle rotating at 4 revolutions / minute.

Each micro mortar is introduced into a mini cone (homothetic of the Abrahams cone) with a base diameter of 3.8 cm, a diameter greater than 1.9 cm and 5.6 cm in height. The mini cone is lifted mechanically, which ensures excellent reproducibility.

The main structural characteristics of the dispersants, as well as the results of the spreading measurements in cm ² of the micro morters are reproduced in the table below.

Characteristics of the dispersant Spread in cm ² of the micro mortar

Ex x tel yl te2 y2 te3 y3 ym 5 15 30 60 90 n ° min min min min min

54 19 8 45 36 17 22.1 119 93 87 82 74

55 19 8 45 17 17 25 3 14.5 156 123 113 105 89

56 19 8 45 25 17 17 3 16.7 166 140 126 113 103

By analogy with Examples 13 to 24: x represents the number of moles of methacrylic acid used to prepare polymethacrylic acid by polymerization.

In the case of examples 55 and 56, a mixture of three polyethylene glycol methyl ethers having respectively (yl), (y2) and (y3) ether functions and leading respectively to an esterification rate (tel), (te2) is used. and (te3), expressed as a percentage relative to the number of carboxylic functions of the starting methacrylic acid. The average value ym of ether functions per molecule is obtained by calculation as follows: ym = (tel.yl + te2.y2 + te3.y3) / (tel + te2 + te3).

Claims

- 29 - CLAIMS

1. Water-soluble or water-dispersible dispersant for cement composition and aqueous suspensions of mineral particles, containing polyether chains and carboxylic functions, optionally partially or totally salified, characterized in that this dispersant is obtained by partial esterification catalyzed by the introduction of a base, by reacting: - at least one polycarboxylic acid containing on average at least 6 carboxylic functions per molecule, and obtained by polymerizing at least one unsaturated carboxylic acid; - And at least one polyether containing a free hydroxyl group which can react with a carboxylic function of said polycarboxylic acid.

2. Dispersant according to claim 1, characterized in that the base is sodium hydroxide.

3. Dispersant according to claim 1, characterized in that the base is lithium hydroxide.

4. Dispersant according to any one of claims 1 to 3, characterized in that 10 to 90% of the available carboxylic functions of the polycarboxylic acid are esterified.

5. Dispersant according to claim 4, characterized in that 30 to 70% of the available carboxylic functions of the polycarboxylic acid are esterified.

6. Dispersant according to any one of the preceding claims, characterized in that its weight average molecular weight, measured by liquid phase chromatography by gel permeation, with polyethylene glycol calibration, varies from approximately 1000 to approximately 1,000,000. - 30 -

7. Dispersant according to claim 6, characterized in that its weight average molecular weight, measured by liquid phase chromatography by gel permeation, with polyethylene glycol calibration, varies from approximately 10,000 to approximately 80,000

8. Dispersant according to any one of the preceding claims, characterized in that the polycarboxylic acid is obtained by polymerization of a monomer mixture containing as essential component acrylic acid and / or methacrylic acid and, optionally, at least another monomer with one or more ethylenic unsaturations which can be copolymerized with acrylic acid and methacrylic acid.

9. Dispersant according to claim 8, characterized in that the polycarboxylic acid is obtained by polymerization of acrylic acid and methacrylic acid.

10. Dispersant according to claim 8, characterized in that the polycarboxylic acid is obtained by polymerization of acrylic acid.

11. Dispersant according to claim 8, characterized in that the polycarboxylic acid is obtained by polymerization of methacrylic acid.

12. Dispersant according to any one of the preceding claims, characterized in that the polyether is a polyalkylene glycol alkyl ether, preferably a mixture of polyalkylene glycol alkyl ethers of formula X (OY) nOH in which:

- X represents an alkyl group of 1 to 8 carbon atoms, preferably from 1 to 4 carbon atoms, even better, X is a methyl radical;

- n is an integer varying from 3 to 500;

the polyalkylene glycol alkyl ether or the mixture of polyalkylene glycol alkyl ethers is such that the average molar ratio of the oxyethylene units to the oxyalkylene units (YO) varies from approximately 0.5 to 1. - 31 -

13. Dispersant according to claim 12, characterized in that the average molar ratio of the oxyethylene units to the oxyalkylene units (YO) varies from 0.7 to l.

14. Dispersant according to claim 12 or 13, characterized in that the polyether consists of:

a polyethylene glycol alkyl ether, optionally containing oxypropylene units,

- or, of several polyethylene glycol alkyl ethers, optionally containing oxypropylene units, of average molecular weight by different weight,

- And, optionally, one or more polypropylene glycol alkyl ethers, of average molecular weight in different weights, which may contain oxyethylene units.

15. Dispersant according to claim 14, characterized in that the polyether is a polyethylene glycol methyl ether containing of the order of 10 to 150 oxyethylene units, or else a mixture of polyethylene glycol methyl ethers essentially differentiating by the length of the chain of oxyethylene units, this mixture comprising, on average per molecule, of the order of 5 to 50 oxyethylene units.

16. A method of manufacturing a dispersant according to any one of claims 1 to 15, characterized in that one reacts, in the presence of water and a base, at a temperature between 160 and 200 ° VS :

- At least one polycarboxylic acid obtained by polymerization of at least one unsaturated carboxylic acid, containing on average at least six carboxylic functions per molecule;

17. Combination of dispersing agents characterized in that it consists of at least one dispersant defined in any one of claims 1 to 15 and at least one dispersant, water-soluble or water-dispersible, comprising - 32 - at least one amino-alkylene phosphonic group, optionally salified, and at least one polyoxyalkylated chain, and corresponding to the formula: Ri

[R-0 (R-0) n] r _{+ q} [Q (-N.) Y] A-PO3H2 in which:

. R is a hydrogen atom or a saturated or unsaturated monovalent hydrocarbon group containing from 1 to 18 carbon atoms and optionally one or more heteroatoms,. the Ri's are similar or different from each other and represent an alkylene such as ethylene, propylene, butylene, amylene, octylene or cyclohexene, or an arylene such as styrene or methylstyrene; the Ri optionally contain one or more heteroatoms,. Q is a hydrocarbon group comprising from 2 to 18 carbon atoms and optionally one or more heteroatoms,

. A is an alkylidene group having from 1 to 5 carbon atoms. . the Rj are similar or different from each other and can be chosen from:

* the group A-PO3H2, A having the abovementioned meaning, * the alkyl group comprising from 1 to 18 inclusive carbon atoms and which may carry groups [R-0 (R_-0) _n ] R and R1 having the above-mentioned meanings,

* and the group

/ Rk -B-N.

A-P03H2

- Rk designating a group such as Rj,

- B denoting an alkylene group comprising from 2 to 18 inclusive carbon atoms,. "n" is a number greater than 0,

"r" is the number of groups [R-0 (Ri-0) n] carried by the set of Rj, "q" is the number of groups [R-0 (Ri-0) n] carried by Q, the sum "r + q" is between 1 and 10, "y" is an integer between 1 and 3, - 33 -. Q, N and Rj can together form one or more cycles, this or these cycles may also contain one or more other heteroatoms.

18. Combination of dispersing agents according to claim 17, characterized in that the dispersant, water-soluble or water-dispersible, comprising at least one amino-alkylene phosphonic group, optionally salified, and at least one polyoxyalkylated chain, corresponds to the formula:

[R-0 (Ri-0) n] _q [Q (- N.) Y] A-PO3H2

in which :

. R is a hydrogen atom or a monovalent hydrocarbon group, saturated or unsaturated, having from 1 to 8 carbon atoms and, optionally, one or more heteroatoms;

, Ri represent ethylene or propylene or a mixture of ethylene and propylene. Preferably, 60 to 100% of the Ri are ethylene groups; . Q is a hydrocarbon group having 2 to 8 carbon atoms and, optionally, one or more heteroatoms;

. A is the methylene group;

. the Rj are similar or different from each other and can be chosen from:

* the group CH2-PO3H2, * and the group

/ Rk -B-N.

CH2-PO3H2 - Rk denoting a phosphonic group such as Rj, - B denoting an alkylene group comprising from 2 to 4 carbon atoms,. "n" is an integer between 10 and 250,. "q" is an integer equal to 1 or 2,. "y" is an integer equal to 1 or 2. - 34 -

19. Adjuvant for aqueous suspensions of mineral particles and mixtures based on hydraulic binder, characterized in that it is in the form of a uniform mixture comprising:

- some water ; - at least one non-water-soluble or slightly water-soluble defoaming agent;

- at least one water-soluble or water-dispersible dispersant, defined in any one of claims 1 to 15, optionally in combination with at least one water-soluble or water-dispersible dispersant, comprising at least one amino-alkylene phosphonic group, optionally salified, and at least a polyoxyalkylated chain, and corresponding to the formula set out in claim 17;

- at least one organic compound (C) containing:. at least one primary, secondary or tertiary amine function, optionally partially or totally neutralized with a Brônsted acid, organic or mineral; . and at least one alkyl or alkyl-aryl chain, linear or branched, saturated or unsaturated, comprising at least 8 carbon atoms, and optionally heteroatoms, chosen from oxygen, sulfur or nitrogen;

- at least one mineral stabilizer when the pH of said mixture is greater than 7;

- optionally, an acid or a base to adjust the pH of said mixture.

20. Adjuvant according to claim 19, characterized in that the mineral stabilizer is sepiolite.

21. Use of a dispersant according to any one of claims 1 to 15 or of a combination of dispersants according to claim 17 or 18 or of an adjuvant according to claim 19 or 20, for fluidizing and improving the homogeneity and the workability of cement compositions with reduced water content and aqueous suspensions of mineral particles. - 35 -

22. Cement compositions comprising a dispersant according to any one of claims 1 to 15, or a combination of dispersants according to claim 17 or 18, or an adjuvant according to claim 19 or 20.

23. Aqueous suspensions of mineral particles comprising a dispersant according to any one of claims 1 to 15, or a combination of dispersants according to claim 17 or 18, or an adjuvant according to claim 19 or 20.