WO2002022520A1

WO2002022520A1 - Cement material comprising a dendritic polymer

Info

Publication number: WO2002022520A1
Application number: PCT/FR2001/002818
Authority: WO
Inventors: Yves Bomal; Xavier Noulhianne; Jean-François SASSI; Gilles Orange
Original assignee: Rhodia Chimie
Priority date: 2000-09-18
Filing date: 2001-09-11
Publication date: 2002-03-21
Also published as: AU2001290006A1; FR2814164A1; FR2814164B1

Abstract

The invention concerns a cement material comprising a hydraulic binder, granular elements and a dendritic polymer capable of complexing ionic species. Such a material exhibits enhanced mechanical strength.

Description

CEMENT MATERIAL COMPRISING A DENDRITIC POLYMER.

The present invention relates to a new cementitious material comprising a particular dendritic polymer, as well as to the articles obtained from these cementitious materials.

Mortars, grouts or concretes are mainly mineral cement materials which conventionally include a hydraulic binder, granular elements of variable size and one or more additives. Hydraulic binders are for example cements, lime, plasters, etc. The additives which can be used are agents which modify the physical characteristics of the cementitious material or of the articles obtained from this material, for example, the mechanical properties, the fluidity, the setting time, etc. Cementitious materials are complex systems and one of the recurring problems in the field of concrete is to increase the mechanical flexural properties of the articles obtained from this material without degrading other characteristics. In particular, the fluidity of the cement paste obtained by mixing the cement material with water is an essential property not to be degraded. In fact, when the viscosity of the cement paste is high, the paste becomes difficult to handle. In addition, during the mixing of a cement paste of high viscosity, it promotes the entrainment of air in the paste which decreases the density of the final material which is then weakened. In order to limit these undesirable side effects, it is possible to envisage adding additives to the material which make it possible to reduce these effects, for example fluidizing agents and / or agents limiting air entrainment. However, it is important to limit the number and quantity of additives used in cementitious materials. An object of the invention is to provide materials, for example concrete articles, having high mechanical properties, in particular improved flexural strength, without modifying the rheology of the cement paste resulting from the mixing of the cement material with the water.

This object and others which will appear on reading the description are achieved by the present invention which relates to a cementitious material comprising a hydraulic binder, granular elements and at least one dendritic polymer capable of complexing the ionic species.

The invention also relates to the use of dendritic polymers in a cementitious material comprising a hydraulic binder and granular elements to increase the flexural strength of the article obtained.

In the following description, the term “cementitious material” designates mainly mineral compositions which contain a hydraulic binder and granular elements, whatever their size. In particular, this term includes materials which contain as a hydraulic binder binders other than cement as well as materials which contain additives, and materials with added water. The term "concrete" here includes not only concrete but also mortars and grouts.

By adding a dendritic polymer capable of complexing the ionic species present, that is to say a polymer having a particular molecular geometry and a particular reactivity with respect to the hydraulic binder, the mechanical properties in bending of the material are increased. resulting article without modifying the viscosity of the cement paste. The use of a dendritic polymer does not require the addition of additional additives, in particular a fluidizing agent. Dendritic polymers are polymer structures with numerous branches. Among dendritic polymers, a distinction is generally made between dendrimers and hyperbranched polymers. These two types of structures can be used for the invention.

The term “dendrimer” is understood to mean a polymer structure having regular, tree-like connections, generally controlled, and which may have symmetry. They are for example produced by tree growth of compounds having a functionality greater than 2, the growth being initiated around a core molecule. Such structures are for example described in D.A. Tomalia, A.M. Naylor and W.A. Goddard III Angevfemgte Chemie, Int. Ed. Engl. 29, 138-175 (1990).

By hyperbranched polymer is meant a branched polymer structure obtained by polymerization in the presence of compounds having a functionality greater than 2, and the structure of which is not perfectly controlled. They are often statistical polymers. The hyperbranched polymers can for example be obtained by reaction between, in particular, multifunctional monomers, for example trifunctional and bifunctional, each of monomers carrying at least two different reactive polymerization functions.

Dendritic polymers generally have a substantially globular shape with a size varying from a few nanometers to several tens of nanometers. The ramifications of molecular construction have their ends, the functionality of which can be modulated. By definition, the number of ends per macromolecule is greater than 2.

The dendritic polymer capable of complexing the ionic species can be chosen from dendritic polymers comprising at least one function capable of complexing the ionic species chosen from:

- the salts of carboxylic acids, or their precursors such as carboxylic acic _^, carboxylates, inorganic or organic esters, organic or inorganic anhydrides, acyl halides,

- sulfonates or their sulfonic acid precursors, - sulfates,

- phosphonates or their phosphonic acid precursors,

- the mono or polyalcohols and the corresponding alcoholates

- β-diketones

- β-ketoesters, - saccharide residues,

- amines, or ammoniums.

According to a particular embodiment, the dendritic polymer capable of complexing the ionic species comprises an acid function dissociated at the pH of the cement paste, preferably carboxylic acid. In this case, the acid function can be in the form of a salt and the counterion associated with the acid can be chosen from sodium, potassium or calcium, preferably sodium or calcium.

The dendritic polymer useful in the present invention is capable of complexing the ionic species of the hydraulic binder, in particular, the dendritic polymer is capable of complexing the cationic species such as calcium or the anionic species such as silicates.

The dendritic polymers useful for carrying out the invention are for example polypropyleneimines, copolyesters, polyamidoamines and copolyamides. By way of example, mention may be made of polypropylene imines with carboxylic functional groups, for example the compounds sold by the company DSM under the name ASTRAMOL ™, the polyamidoamines containing carboxylic ends, for example the compounds sold by the company Dendritech under the name STARBURST ™, the hyperbranched polyesters functionalized, for example by succinic anhydride, of the type of those sold by the company Perstorp under the name Boltorn ™. More particularly, the dendritic polymers useful for carrying out the invention are hyperbranched copolyesters and hyperbranched copolyamides. The preferred copolyamides are non-fully aromatic hyperbranched copolyamides. Such compounds are described in the patent application filed in France on May 5, 1999 under the number 99/05885. They are for example obtained by reaction between :.

Has at least one monomer of formula (I) below:

(I) AR-Bf in which A is a reactive polymerization function of a first type, B is a reactive polymerization function of a second type and capable of reacting with A, R is a hydrocarbon entity, and f is the total number of reactive functions B per monomer: f> 2, preferably 2 <f <10;

A and at least one monomer of formula (II) below: (II) A'-R'-B 'or the corresponding lactams, in which A', B ', R' have the same definition as that given above respectively for A, B, R in formula (I); ^• the molar ratio l / ll is defined as follows:

0.05 <l / ll and preferably 0.125 <l / ll <2;

- ^ and at least one of the entities R or R 'of at least one of the monomers (I) or (II) is aliphatic, cycloaliphatic or arylaliphatic.

According to a preferred arrangement of the invention, the hyperbranched copolyamide is such that:

Δ the hydrocarbon entities R, R 'of the monomers (I) and (II) respectively, each comprise:

V i at least one linear or branched aliphatic radical;

V ii and / or at least one cycloaliphatic radical; V iii and / or at least one aromatic radical comprising one or more aromatic rings; these radicals (i), (ii), - (iii) possibly being substituted and / or comprising heteroatoms; Δ A, A 'is a reactive function of the amino type, amine salt, or of the acid, ester, acid halide or amide type;

Δ B, B 'is a reactive function of the acid, ester, acid halide or amide type or of the amino type, amine salt.

Thus, the reactive polymerization functions A, B, A ', B' more especially retained are those belonging to the group comprising the carboxylic and amino functions. By carboxylic function is meant any COOH acid, ester or anhydride function.

In the case where A, A ′ corresponds to an amine or to an amine salt, then B, B ″ represents an acid, an ester, an acid halide or an amide and vice versa.

The hyperbranched polymer can advantageously consist of a mixture of several different monomers (I) and of several different monomers (II), provided that at least one of these monomers is aliphatic, cycloaliphatic or arylaliphatic. In addition to the multifunctional monomers (I) and the bifunctional monomers (II), it is possible to envisage having a hyperbranched polymer according to the invention also comprising, as constituent elements, mono or multi-functional monomers (III) of the type "core" (or "nucleus") and / or monofunctional monomers (IV) of the "chain limiter" type. The “core” type monomers optionally included in the hyperbranched copolyamide according to the invention can be those of formula (III) below:

(III) R ¹ (B ") _n in which: ° R ¹ is a substituted or unsubstituted hydrocarbon radical, of the silicone, linear or branched alkyl, aromatic, alkylaryl, arylalkyl or cycloaliphatic radical which may comprise unsaturations and / or heteroatoms;

° B "is a reactive function of the same kind as B or B ';

° n> 1, preferably 1 <n <100. The monomers of the "chain limiter" type optionally included in the hyperbranched copolyamide according to the invention can be those of formula (IV):

(IV) R ² -A "in which:

° R ² is a substituted or unsubstituted hydrocarbon radical, of the silicone, linear or branched alkyl, aromatic, arylalkyl, alkylaryl or cycloaliphatic radical which may comprise one or more unsaturations and / or one or more heteroatoms. ° and A "is a reactive function of the same nature as A or A '.

According to one embodiment, at least part of the bifunctional monomers (II) are in the form of a prepolymer. It may be the same with regard to the monomers (III) of the "core" type or even the monomers (IV) of the "chain limiter" type. The radicals R ¹ and R ² can advantageously comprise functionalities which confer particular properties on the hyperbranched polymer. These functionalities do not react with the functions A, B, A ', B' during the polymerization of the PAHB.

According to a preferred embodiment, f = 2 so that the monomer (I) is trifunctional: ARB ₂ , A = amino function, B = carboxylic function and R = aromatic radical.

The hyperbranched polymer obtained from monomers I and II can be likened to tree structures endowed with a focal point formed by the function A and a periphery furnished with terminations B. When they are present, the monomers (III) form nuclei. Advantageously, the hyperbranched polymer can comprise monofunctional monomers (IV) "chain limiter", located at the periphery of the dendrimers.

Furthermore, the bifunctional monomers (II) are spacers in the three-dimensional structure. They allow a control of the branch density and are in particular at the origin of the interesting properties of hyperbranched polymers.

The monomers (III) and (IV) make it possible to control the molecular weight.

Advantageously, the monomer (I) is for example chosen from the group comprising:

- 5-amino-isophthalic acid, - 6-amino-undecandioic acid,

- 3-aminopimelic diacid,

- aspartic acid,

- 3,5-diaminobenzoic acid, - 3,4-diaminobenzoic acid,

- lysine,

- and their mixtures.

Advantageously and for example, the bifunctional monomer of formula (II) is: - ε-caprolactam and / or the corresponding amino acid: aminocaproic acid, and / or para or metaaminobenzoic acid, and / or acid amino-11-undecanoic acid, and or lauryllactam and / or the corresponding amino acid: amino-12-dodecanoic acid.

More generally, the bifunctional monomers of formula (II) can be the monomers used for the manufacture of linear thermoplastic polyamides. Thus, mention may be made of ω-aminoalkanoic compounds comprising a hydrocarbon chain having from 4 to 12 carbon atoms, or lactams derived from these amino acids such as ε-caprolactam.

The preferred bifunctional monomer (II) of the invention is ε-caprolactam.

By way of examples, the monomers (III) may be, for their part: => saturated aliphatic dicarboxylic acids having from 6 to 36 carbon atoms such as, for example, adipic acid, azelaic acid, l sebacic acid, dodecanoic acid,

=> biprimary, preferably saturated linear or branched aliphatic diamines having from 6 to 36 carbon atoms such as, for example, hexamethylenediamine, trimethylhexamethylene-diamine, tetramethylenediamine, n-xylenediamine,

=> Polymeric compounds such as amino polyalkylene oxides sold under the trademark JEFFAMINE ^®, = or alternatively an amino silicone chain, eg polydimethylsiloxane mono or diamine.

=> aromatic or aliphatic monoamines,

=> aromatic or aliphatic monoacids, or = aromatic or aliphatic triamines or triacids.

The monomers (III), preferred "core" are: hexamethylene diamine and adipic acid, JEFFAMINE ^® T403 acid or 1, 3,5-benzene tricarboxylic acid.

According to another characteristic of the invention, the molar ratio of the monomers (IV) to the bifunctional monomers (I) is defined as follows:

^{(/ F)} _≤ 10

() preferably <5

and more preferably still

0 _≤ ^ _≤ 2 00

Concerning the molar ratio of functional monomers (III) "nuclei" compared to multifunctional monomers (I), it can be defined as follows: - {—III) - <.1

() preferably

(I) and more preferably still

0 _≤ ^ _≤ 1 3

Advantageously, the hyperbranched copolyamide can be in the form of particles each consisting of one or more tree structures. Another interesting characteristic of such a copolyamide is that it can be functionalized: 0 at the focal point of the tree structure (s), via monomers (III) carrying the functionality (s) considered,

0 and / or at the periphery of the tree structures, via monomers (IV) carrying the functionality or functionalities considered.

As regards the synthetic aspect, it will be specified that the hyperbranched copolyamides can be obtained by a process which essentially consists in carrying out a polycondensation between monomers (I) and monomers (II) which react with each other and possibly with monomers ( III) and / or (IV); and this under appropriate temperature and pressure conditions. This polymerization takes place in the melt phase, in the solvent phase or in the solid phase, preferably in the melt or solvent phase; the monomer (II) advantageously playing the role of solvent. The process for the synthesis of hyperbranched polymers according to the invention can use at least one polycondensation catalyst.

The polycondensation polymerization is carried out, for example, under conditions and according to a procedure equivalent to those used for the manufacture of the linear polyamide corresponding to the monomers (II). By way of example, one can use the hyperbranched copolyamides described above and having functions capable of complexing the ionic species chosen from carboxylic acids, carboxylates, organic or mineral esters, organic or mineral anhydrides, halides of 'acyles, sulfonic acids, sulfonates, sulfates, phosphonic acids, phosphonates, mono or polyalcohols and corresponding alcoholates, β-diketones, β-ketoesters, saccharide residues, amines and ammoniums .

The functions capable of complexing the ionic species when they are not introduced during the polymerization of the dendritic polymer can be obtained by post polymerization from a monomer making it possible to introduce this function on the dendritic polymer. It is also possible to envisage chemically modifying the existing functions of the dendritic polymer in order to obtain the functions capable of complexing the ionic species. According to a preferred embodiment, the dendritic polymers capable of complexing the ionic species exhibit at least partial miscibility with water and chemical functionalities compatible with the cementitious material, in particular compatible with the hydraulic binder and the granular elements. If the functions capable of complexing the ionic species do not make it possible to effectively dissolve the dendritic polymer, it may also comprise solubilizing groups inert with respect to the cementitious material such as polyalkylene oxide units.

Advantageously, the hyperbranched polymers also have ends and / or a polyalkylene oxide core inert with respect to the cementitious material. According to a preferred embodiment, the ratio between the number of functions capable of complexing and the number of polyalkylene oxide ends is between 0.1 and 1, preferably between 0.3 and 1.

According to a particular embodiment, the dendritic polymer is a dendritic polymer with carboxylic acid functions and comprising polyethylene oxide ends in which the ratio between the number of carboxylic functions and the number of polyethylene oxide is between 0.5 and 1.

According to a particular embodiment, the dendritic polymer is present in the cementitious material, adsorbed on a mineral filler. The mineral filler can be any type of filler capable of developing an interaction with the functionalities of the hyperbranched, for example by a complexing effect. The polymer can be adsorbed on the mineral filler either during the synthesis of the mineral filler, or a posteriori.

The cementitious material of the present invention further comprises a hydraulic binder. A hydraulic binder is a generally mineral substance which has the property of setting and hardening in the presence of water. This hydraulic binder can be any hydraulic binder known in the art, for example cements, plaster, lime. All of these hydraulic binders include ionic species which will complex with the dendritic polymer as defined in the present invention. The cementitious material also includes granular elements. The granular elements have a size of up to several millimeters.

As granular elements, mention may be made of sand, Siθ2, Tiθ2, AI2O3, Zrθ2, Cr2θ3, talc, mica, kaolin, wollastonite, bentonite, metakaolin, crude dolomite, chromium ore, limestone, clinker, vermiculite, periite, gypsum, cellulose, slag. They can be synthetic products. They can be crystallized or amorphous compounds obtained by example by grinding and sieving to the desired size. It is also possible to use condensed silica smoke, ground natural silica, precipitated silica, fumed silica, fly ash.

The fly ash that can be used are generally silicoaluminous ashes from combustion in thermal power plants in particular.

The particle size of these ashes is usually between 0.5 and 200 μm.

The condensed silica smoke, optionally constituting the composition according to the invention, generally has a specific surface of between 20 and 30 m ² / g.

Usually, the amount of granular elements is between 0 and 1000 parts by weight per 100 parts by weight of binder.

According to a particular embodiment, the amount of sand, silica or the other granular elements mentioned in this list, is generally between 0 and 900 parts by weight relative to the same reference as above. In addition, the amount of condensed silica smoke or fly ash is between 0 and 100 parts by weight.

Although it is desired to reduce the number of additives present in the material, additional additives may be introduced therein provided that these do not disturb the expected performance of the concrete. The cementitious material can comprise water-repellent agents, anti-foaming agents, agents which delay setting.

In general, such additives do not represent more than 10 parts by weight per 100 parts by weight of hydraulic binder. Preferably, the amount of additives is between 0 and 5 parts by weight. According to a particular mode, the additive (s) are used in the form of a powder whose average diameter varies from a few nanometers to a few hundred microns. According to one embodiment, the amount of dendritic polymers capable of complexing the ionic species in the material is less than or equal to 5%, preferably between 0.5% and 3% relative to the amount of binder.

To obtain the articles of the invention, the cementitious material described above is mixed with water to form a cementitious paste, this paste is then shaped (molding, casting, injection, pumping, extrusion, calendering) then hardened. Thus, one can proceed by bringing all the elements of the mixture, simultaneously or separately. According to the latter possibility, a composition is generally prepared comprising the hydraulic binder, the granular elements, and all or part of the optional additives previously mentioned in general in solid form. This composition is then mixed with water containing the dendritic polymer, and, if this is the case, the additives not introduced in the previous stage of preparation of the composition, such as liquid additives.

The essential point of the process is that it is implemented so as to obtain a distribution of all the constituent elements as homogeneous as possible in the mass of the article obtained after drying.

The components are mixed by any known means and preferably under shearing conditions, for example using a mixer. The mixing operation is advantageously carried out at a temperature close to room temperature.

From the cementitious material of the invention, and by the choice of the nature, the size and the quantity of the granular elements, it is possible to obtain mortars, for example adhesive mortars, repair mortars, self-mortars. leveling; concretes, for example ordinary concretes, high performance concretes, sprayed concretes, self-leveling concretes; etc. Examples of high performance concretes are described for example in patent applications WO 95/01316, WO 99/28267 and WO 99/58468. According to a particular embodiment, the porosity of the article obtained after hardening of the paste described above is such that less than 10% of the volume of the product consists of pores with a diameter greater than 0.1 μm, preferably less than 8%. The term “porosity” is understood here to mean the porosity of the article obtained, measured by mercury intrusion, this measurement method being known to a person skilled in the art and described for example in the Thesis of the National School of Bridges and Pavements - 1994, Véronique BAROGHEL-BONY, entitled "Microstructural and water characterization of cement pastes and ordinary concretes and at very high temperatures"

Such porosity can for example be obtained with a cementitious material containing an amount of water such that the W / C ratio is less than 0.3. One can also obtain such a porosity by the choice of the size of the elements. granular and / or by adding an anti-foaming agent to the paste. This porosity can be obtained by compressing the paste before hardening.

The following examples are specific examples illustrating the present invention without however limiting its scope. In the following examples, the% are percentages by mass unless otherwise indicated.

Example 1 - Manufacture of a hyperbranched copolyamide with mixed terminations of carboxylic acids and polyalkylene oxides by copolycondensation in the molten phase of 5-aminoisophthalic acid (branching molecule (I) of ARB type?) With A = H and B = COOH). of rε-caprolactam (spacer (H) of type A'-R'-B ') and of Jeffamine ^® M 1000 (polyoxyethylene co-oxypropyiene amino, molecule (IV) chain limiter of type R ² - A "). reaction is carried out at atmospheric pressure in an autoclave of

7.5 I commonly used for the melt phase synthesis of polyesters or polyamides. Are successively loaded into the autoclave 1764.7 g of JEFFAMINE ^® M 1000 (1.5 mol); 543.45 g of 5-aminoisophthalic acid (3 mol); 339.5 g (3 mol) of ε-caprolactam and 0.50 g of a 50% aqueous solution (w / w) of hypophosphorous acid. The reactor is purged by a succession of 4 sequences of evacuation and restoration of atmospheric pressure using dry nitrogen. The reaction mass is gradually heated from 20 to 200 ° C in 100 min., Then from 200 to 260 ° C in 60 min. When the mass temperature reaches 100 ° C., the stirring is started with a rotation speed of 100 revolutions per minute. Distillation begins at a mass temperature of 160 ° C and continues until the temperature of 260 ° C. The reaction mass is maintained at this temperature for 30 minutes, then the system is gradually put under vacuum to reach an absolute pressure of 10 mbar after 30 minutes. Then, the stirring is stopped and the reactor is placed under nitrogen overpressure. The polymer is expelled through the reactor bottom valve.

Example 2

Cementitious materials are prepared comprising. a cement CEM I 52.5 PM ES CP2 • MST type silica smoke sold by the company SEPR, in a quantity such that the silica to cement ratio S / C is equal to 0.15,

• Dehydrant 1922 antifoam sold by CIA in an AM / C ratio equal to 0.004, • water in quantity such that the water to cement ratio E / C is equal to

0.2, and

• an SP Optimas 100 superplasticizer sold by Lafarge, the quantities of superplasticizer in an SP / C ratio equal to 0.003,

• the dendritic polymer of Example 1 (1% by weight relative to the weight of cement).

The dry granular elements are first kneaded in a Perrier type kneader for 10 min, the liquid elements are then incorporated therein, this mixture is kneaded at slow speed for 30 sec, at fast speed for 3 min and then again at speed slow 30 sec. This paste is then poured into PVC molds of size 10x10x100 mm allowing the obtaining of test tubes. The rheology of the cementitious pastes obtained for each mixture is measured by the standardized ISO4109 spreading test.

For each test piece, the density is measured by measuring the size of the test piece with an accuracy of 0.5 mm and measuring the weight of the test piece with a precaution of 0.1 g. The density is thus determined (density in Kg / dm ³ ).

The flexural strength is measured according to the principle of standard NF EN 196-1. The tests are carried out at 20 ° C. The breaking force of the test piece is measured for each test piece after hardening. After rupture of the test piece, from the maximum force obtained, the flexural strength Rf (MPa) is expressed by the formula Rf = (1, 5xLxF) b ³ in which F is the maximum force (in N), L is the distance in mm between supports and the edge of the specimen, the ratio L / b being identical to that defined in the standard. The average value is calculated on 6 test pieces. The results are reported in the following table

Table 1

In this example, an improvement in the flexural strength is observed when the material contains the dendritic polymer. In addition, these examples show that the addition of the dendritic polymer does not disturb the rheology of the mixture and it is noted that the density of the control cement paste is comparable to that of the material comprising the dendritic polymer.

Example 3

A cementitious material is prepared under the same conditions as those described in Example 2 from the following elements:

• CPA CEM I 52.5 PM ES CP2 cement

• MST type silica smoke sold by the company SEPR, in a quantity such that the silica to cement ratio S / C is equal to 0.15,

• Dehydrant 1922 antifoam sold by CIA (0.07% compared to cement)

• water in quantity such that the water / cement ratio W / C is equal to 0.25, and

The results are reported in the following table

Table 2

An improvement in the flexural strength is observed when the material contains the dendritic polymer without modification of the rheology or of the density of the cementitious paste.

Claims

1. Cementary material comprising a hydraulic binder, granular elements and a dendritic polymer capable of complexing the ionic species.

2. Cementary material according to claim 1 wherein the dendritic polymer carries at least one function capable of complexing the ionic species chosen from carboxylic acids, carboxylates, organic or mineral esters, organic or mineral anhydrides, acyl halides , sulfonic acids, sulfonates, sulfates, phosphonic acids, phosphonates, mono or polyalcohols and the corresponding alcoholates, β-diketones, β-ketoesters, saccharide residues, amines and ammoniums.

3. Cementary material according to claim 1 or 2 wherein the dendritic polymer is capable of complexing the cationic species.

4. Cementary material according to any one of the preceding claims 1 to 3 in which the dendritic polymer additionally comprises solubilizing groups.

5. Cementary material according to claim 4, in which the dendritic polymer comprises, as solubilizing group, ends and / or a polyalkylene oxide core.

6. Cementary material according to claim 5 in which the ratio between the functions capable of complexing the ionic species and the polyalkylene oxide ends of the dendritic polymer is between 0.1 and 1.

7. Cementary material according to any one of claims 1 to 6 wherein the dendritic polymer comprises polyethylene oxide functions and carboxylic acids and / or carboxylates.

8. Material according to any one of claims 1 to 7 wherein the dendritic polymer is a dendrimer.

9. Material according to any one of claims 1 to 7 wherein the dendritic polymer is a hyperbranched polymer.

10. Material according to any one of claims 1 to 9 wherein the dendritic polymer is a copolyamide or a copolyester.

11. Cementary material according to any one of claims 1 to 10 in which the amount of dendritic polymer capable of complexing the ionic species in the material is less than or equal to 5% relative to the amount of hydraulic binder.

12. cementitious material according to any one of claims 1 to 11 comprising water in an amount such that the W / C ratio is less than 0.3, in which E is the amount of water and C the amount of binder hydraulic.

13. Cementary material according to any one of claims 1 to 12 wherein the dendritic polymer is adsorbed on a mineral filler.

14. Articles obtained from the material as defined according to any one of claims 1 to 13.

15. Articles according to claim 14 in which less than 10% of the volume of the article consists of pores having a diameter greater than 0.1 μm.

16. Use of a dendritic polymer capable of complexing the ionic species in a cementitious material comprising a hydraulic binder and granular elements to improve the flexural strength of the material obtained.

17. Use of a dendritic polymer capable of complexing the ionic species in a concrete to improve the flexural strength of the material obtained.

18. Use of a dendritic polymer capable of complexing the ionic species in an adhesive mortar to improve the flexural strength of the material obtained.