The present invention relates to a mineral binder based on phosphates. This type of binder used in building products resulting from an acid-base reaction between a metal oxide and a salt or a derivative of phosphoric acid. The most basic oxides which react with phosphoric acid or one of its derivatives form acid, when mixed with water, a homogeneous mass which hardens with time at room temperature. Among the known phosphate cements include the Phosphomagnesium cements that have been developed to compete with synthetic resins since they allow to obtain concrete fast setting with an almost immediate appearance of popular resistance. They find particular application in the biomedical field and in dentistry in the fast repair of roads, tracks or bridges, or in the ion encapsulation of hazardous waste. A cement such Cerami called peak developed in Bat s- Kingdom s is obtained by mixing the magnesium oxide or magnesia, with potassium monophosphate KH2 P0. In the presence of water, magnesia reacts with the phosphate groups under acidic conditions to form an insoluble phosphate phase which hardens and which has the properties of a ceramic. This phase is the k-struvite formula MgKP0 4 , 6H 2 0. The formation of this phase of reaction is very rapid and requires the use of a retarder. Boric acid is often used to increase the time of workability of this type of cement. However, according to European regulations including REACH Directive, boric acid is classified as toxic to reproduction. Other solutions to control the setting time are therefore considered. Articles describe the possibility to lengthen the setting time and thus I 'ouvrabi ity using a particular magnesium oxide, namely calcined magnesia at high temperature and by adjusting the particle size of the basic metal oxide being in. But this does not achieve the setting time or duration of workability comparable to those obtained for Portland cement-based systems. Another disadvantage of this type of system is linked to the strong

exothermicity of the reaction which takes place between the magnesia and phosphate. Boric acid used as a timer does not control the thermodynamics of the reaction. The end user must therefore take into account the highly exothermic resulting in significant evaporation of water in the system during the preparation of the building material.

On the other hand, another drawback related to the too high reactivity and making these systems is the occurrence of whitened areas in the surface of the cured material, which reflects a salt surfacing unreacted. This is efflorescence that gives an important aesthetic defect that is not acceptable for the desired applications.

It is necessary to develop systems based phosphate binders used in mortar compositions that present time longer workability compatible with popular applications, and does not have the drawbacks described above. It is in this context that the present invention takes place.

The present invention relates to a mineral binder based on phosphate obtained by reaction between at least one basic component and an acid phosphate salt in the presence of a retarding agent which is a salt X + A " whose solubility in aqueous medium measured this is at 25 ° higher than that of acid phosphate salt, and wherein

X * " is a cation selected from alkali metals, alkaline earth metals, zinc, aluminum and ammonium ion, and A- is an acetate anion, formate, benzoate, tartrate, oxalate, oleate, bromide or iodide.

The presence of the retarding agent as described above -Dessus advantageously allows control of the kinetics and the exothermicity of the acid-base reaction that takes place between the or these basic components and the acid phosphate salt. The use of such a retarding agent avoids the use of boric acid or its derivatives.

The basic component, performing the basic role in the acid-base reaction for obtaining the binder of the invention is selected from metal oxides, metal hydroxides or sulfates. oxides

metal can be calcium oxide, magnesium oxide, zinc oxide, aluminum oxide and / or iron oxide. The metal oxide may also be introduced in the form of a more complex inorganic compound which comprises one or more metal oxides. We include in this category silicates, metallurgical slags (for example dairy or dairy steelworks blast furnaces), lime, fly ash, dolomite, mica, kaolin and / or metakaolin. Metal hydroxides such as magnesium or calcium hydroxide may also be used as basic component for forming the binder according to the present invention. Sulfates such as calcium sulfate can also be used as basic component for forming the binder according to the present invention. Sources of calcium sulfates include plaster, gypsum, hemihydrate and / or anhydrite. It is possible to use a mixture of these different sources of metal oxides or hydroxides and sulfates for preparing the binder according to the present invention.

Preferably, the binder according to the present invention is obtained from a mixture of at least two basic components, one of them at least being selected from magnesium oxide, calcium hydroxide or magnesium, wollastonite, alumina, metallurgical slags, and calcium sulfate. The additional basic component, can then be selected from kaolin, metakaolin, fly ash, lachaux, ladolomite, calcined clays, mica and / or talc, for example.

Acid phosphate salt participating in the reaction aci do- basic training of the binder according to the present invention is selected from:

-the potassium hydrogen phosphate, calcium, magnesium, aluminum, sodium or ammonium,

-the di potassium hydrogen phosphate, calcium, magnesium, aluminum, sodium, or ammonium,

-the pyrophosphates acid potassium, calcium, magnesium, aluminum, sodium or ammonium, and / or

-the potassium acid polyphosphates, calcium, magnesium, aluminum, sodium or ammonium.

These salt s acid phosphates may be used alone or mixed.

Hydrogen phosphates are salts comprising anion HP0 Γ 2 " . The dihydrogen phosphates are salts comprising anion Γ H 2 P0 " . The acid pyrophosphates are salts derived from pyrophosphoric acid and answered MH3P2O7 formulas M2H2P2O7 and M3HP2O7. Polyphosphates acids are salts derived from polyphosphoric acid and have the general formula
in which n is an integer strictly greater than 2.

Acid phosphate salt thus comprises at least one proton capable of being released during the dissolution in water of the binder, resulting in acid etching to dissolve the metal oxide present in solution.

Preferably, the acid phosphate salt is selected from potassium dihydrogenphosphate KH 2 P0 (MKP), ammonium dihydrogenphosphate (NH 4 ) H 2 P0 (MAP), Γ diammonium hydrogen phosphate (NH 4 ) 2 HP0 4 (DAP), calcium dihydrogen phosphate Ca (H 2 P0 4 ) 2 , sodium dihydrogen phosphate NaH 2 P04, Γ hydrophosphate aluminum AIH 3 (P0) 2 xH 2 0, calcium metaphosphate Ca (HP03) 2 , dihydrogen phosphate Mg (H 2 P0) 2 magnesium hydrogenphosphate or tri aluminum AI (H 2 P0) 3 . Preferred acidic phosphate salts are those that do not release ammonia during the reaction and therefore are selected from potassium dihydrogenphosphate KH 2 PC¼ (MKP), calcium dihydrogen phosphate Ca (H 2 P0 4 ) 2 , metaphosphate of calcium Ca (HP0 3 ) 2, sodium dihydrogen phosphate NaH 2 P04, and Γ aluminum hydrophosphate AIH 3 (P0 4 ) 2, xH 2 0, magnesium dihydrogen phosphate Mg (H 2 PC¼) 2 or sorting of hydrogen aluminum AI (H 2 P0) 3 .

The retarding agent used to control the reactivity of the binder according to the present invention is an ionic salt of the formula X + A in which the cation X + is selected from alkali metals, alkaline earth metals, zinc, aluminum and the ammonium ion, and the anion A " is selected from the acetate anions, formate, benzoate, tartrate, oleate, oxalate, bromide or iodide. the cation can be selected from alkali metals, alkaline earth metals, aluminum and ammonium ion and the anion A " may be selected from lesanions acetate, formate, benzoate, tartrate, oleate, bromide or iodide. These salts are solublesdans water and must, in their role retardant, be more soluble in aqueous media that the acidic phosphate salt. Table 1 below gives -Dessous Illustrative solubility in grams in 100 mL of water at 25 ° Cde utilizable salts as retardants.

Table 2 shows the solubility in grams in 100 mL of water at 25 ° Cde acid phosphate salts may be used in the binder-forming reaction according to the present invention.

Table 2

The retarding agent is selected depending on the acid phosphate salt used in the binder-forming reaction. It is essential that its solubility is greater than that of the acid phosphate salt.

Preferably, a salt is chosen as retarder whose cation is identical to the cation of the acidic phosphate salt involved in the binder forming reaction. Retardants whose anions are acetates or for at mid es are preferred. These anions possible to obtain a longer workability time and better control of the exothermic reaction. The quantity of retarding agent is between 1 and 10% by weight of the total amount of binder components. Preferably, the amount of retarding agent is between 2 and 7% by weight.

It is possible, without departing from the scope of the present invention to use a mixture of several retardants in a binder formulation. Preferably, is used as retarding agents a mixture of salts whose anions are selected from acetates, formates and oxalates. One can for example use as retarding agents a mixture of acetate and oxalate or a mixture of formate and oxalate. In the case of mixtures, the total amount of retarding agents remains between 1 and 10% by weight, preferably between 2 and 7% by weight of the total amount of the binder components.

The binder according to the present invention may comprise, in addition to the acid phosphate salt, another phosphate compound selected from salts of orthophosphates, polyphosphates or pyrophosphates wherein the cation is selected from sodium, potassium, calcium or the ammonium ion. Salts of orthophosphates are salts derived from orthophosphoric acid comprising the anion PO 3 " . The pyrophosphates are salts derived from pyrophosphoric acid comprising the anion Ρ 2 Ο / 4" . Particular examples are sodium tripolyphosphate Na 5 P 3 Oi 0 (Na-TPP) or calcium pyrophosphate C ^ C ^. This other phosphate compound is participating in the retarding effect. For example, the solubility of sodium tripolyphosphate is about 14.5 g in 100 ml water at 25 ° C. That of sodium pyrophosphate Na 4 P 2 O / is approximately 7 under the same conditions. 3 this extra phosphate compound is a base, it is

i mportant that the quantities introduced into the binder composition, however, remain low, to keep the phosphorus-based constituent of acid character i ntervenant in the reaction aci do-basic.

The present invention also relates to a composition of mortar or concrete includes at least one preview iant as described above. The composition contains aggregates, aggregates and / or sand, and then fluent mortar or concrete according to the tail of the aggregates. al small hurt aggregates such as expanded clays, perl ite, aerogels, of vermicul ite, expanded glass or expanded polystyrene can also be uti ized in the mortar or concrete composition according to the present i nvention. These compounds j ouent including rheology, hardness or the final appearance of the product. They are generally formed of sand sil iceux, limestone and / or sil icocalcaires. The composition may also include components called lers wire, limestone or sil iceux and other optional additives and adj uvants conferring particul ières properties. Examples include, rheological agents, retention agents Water, coaches agents air, thickening agents, protective agents against the growth of algae and fungi such as biocides, fungicides, algaecides, bactericides , dispersing agents, pigments, accelerators and / or retarders, have nsi that other agents for amel iorer decision, hardening, stabi lity of the products after appl ication and including aj uster color, the ouvrabil ity, implementation or i mperméabil ity.

The present invention also relates to building products, such as j mortars anointed oiement s j oi nt s of tiles, tile adhesives, screeds, floor coatings, technical mortars, insulation mortars or facade coatings obtained from the def of concrete or mortar composition ined above. These products are obtained by mixing the composition with water, the thus formed paste-like composition is then cured. SDUS the term technical mortars, it includes special mortars formulated for appl ications particul ières such as mortars Envelope Sealers LEMENT, repair mortars, mortars hourdage or anchoring mortars. Prefabricated elements can also be obtained r party compositions

comprising the binder according to the present invention. constructions of the products according to the invention can be prepared on site or precast.

The resulting products have workability time consistent with the desired applications, since the product remains usable after mixing for a longer time when the composition does not include the retardant. Moreover, the products obtained from the compositions of mortar or concrete according to the present invention does not defective sd aesthetics due to phenomena lorescence eff.

-after the examples below illustrate the invention without limiting its scope.

In the following examples, ladurée practical usage is measured for different compositions of binders. The potlife is the maximum time after the preparation of the binder, that is to say after the mixing of the various pulverulent constituents with the mixing water, during which the wet paste thus obtained may be used. Determination of the pot life is achieved by measuring the time elapsing between the time the product is prepared with the desired paste consistency and the time when the viscosity of the paste has increased so that the product longer sufficiently fluid to be applied. The potlife is correlated with the initial setting time due to the curing of the paste, the setting time being measured by the Vicat test according to the EN 196-3 standard.

The workability time is defined as the length of time a fresh dough retains a viscosity low enough to be easily applied with good handling.

For all examples below, powder products are mixed together before adding the mixing water to prepare fresh dough. The amount of water which is added and given in% by weight of water may vary depending on the application and the desired maneuverability so as to obtain the desired consistency of the paste. The determination of the consistency of the fresh dough is made at the shaking table according to EN 1015-3 standard. The powder mixture is mixed with water so as to obtain a homogeneous paste. The fresh dough is poured into a given mold on the set of a shaking table defi ned. After removal from the mold, fresh pulp is subjected to a given number of vertical shaking. The diameter of f raîche circle of dough is measured. Identical diameters allow s to ensure that the consistency of pasta are comparable.

Different compositions of iants according to the present invention are prepared. Measurements of practice duration of util ization are performed on identical compositions with or without retardants.

The compositions of the iants are prepared by mixing the basic components or with the acid phosphate salt in the presence of salt util ized as retarding agent.

The content of each component is given in weight percent, the total sum of quantities of pulverulent products being 100% The mixing water is aj outed is indicated for each example and corresponds to the quantity of water required for obteni r the same dough consistency. The water content indicated in each example corresponds to the amount which is aj outed to a mixture which comprises 100% of powdery products.

The examples below show that -after the practical length of appl ication of the paste obtained by mixing the iant according to the present invention with water is increased in the presence of the retarding agent. The binder is obtained by reaction between one or pl ultiple basic components and an acid phosphate salt and is therefore by highly reactive in nature. Therefore, mortars compositions prepared from this the iant, which may include other components such as sand or fi 11 ers can also participate in the increase in the practice time of application, allow to avoi r practical periods of application still meil leuers.

.Example 1

A mixture consisting of 50% by weight of lightburned magnesium oxide (ISMAF) and 50% by weight of di hydrogenphosphate potassi um

KH 2 PC¼ (Prayon) was prepared. Water is added to the powder mixture thus obtained in an amount of 20% by weight relative to the total quantity of pulverulent constituents. Practice useful life measured in the paste is from 0.5 min. The same composition was prepared by adding 3% by weight of potassium acetate (SGMA Aldrich) as retarding agent. The amount of water added is 20% by weight. The potlife measured pulp comprising the retarder is then 7 min.

.Example 2

A mixture consisting of 50% by weight of CaS0 3 wollastonite (Nordkalk) and 50% by weight of calcium dihydrogen phosphate monohydrate Ca (H 2 P0) 2-H 2 0 (Budenheim) was prepared. Water is added to the powder mixture thus obtained in an amount of 50% by weight relative to the total quantity of pulverulent constituents. Practice measured duration of use of this paste is 0.2 min. The same composition was prepared by adding 3% by weight of calcium acetate (SGMA Aldrich) as retarding agent. The amount of water added is 50% by weight. The potlife measured pulp comprising the retarding agent is gold al 3 min.

Eïxemple 3

Three different magnesium oxide mixtures strongly calcined at high temperature (1500 ° C) and sintered (Grecian Magnesite) and potassium dihydrogenphosphate KH 2 P0 (Prayon) are prepared by varying the weight ratio of MgO: MKP.

3-1 the composition is 25% by weight of MgOet 75% by weight of MKP. The amount of water added is 20% by weight relative to the total amount of pulverulent compounds.

3-2 the composition is 50% by weight of MgO and 50 wt% of MKP. The amount of water added is 21% by weight relative to the total amount of pulverulent compounds.

3-3 The composition is 75% by weight of MgO and 25 wt% of MKP. The amount of water added is 22% by weight relative to the total amount of pulverulent compounds.

Practical application times of these three pulps are measured and are 17 min respectively for the pulp obtained from the composition

3- 1, 5 min for the dough obtained from the composition 3-2 and 4 min for the dough obtained from the composition 3-3.

3% by weight of potassium acetate (SGMA Aldrich) is added to each of compositions 3-1, 3-2 and 3-3, maintaining the MgO ratios: MKP which are respectively 25/75, 50/50 and 75/25. The mixing water is added in the same proportions. Practical periods pulp obtained from use of the compositions 3-1, 3-2 and 3-3 which was added the retarding agent were measured and are respectively equal to 80 min for the dough obtained from the composition 3 -1, 50 min for the dough obtained from the composition 3-2 and 18 min for the dough obtained from the composition 3-3.

.Example 4

Several compositions with a weight ratio MgO: MKP same as the composition 3-3 are prepared from the same raw materials.

4-1 the composition is 75% by weight of MgO strongly calcined at high temperature and 25% by weight of MKP.

4-2 the composition comprises 37.5% by weight of MgO strongly calcined at high temperature, 12.5% ​​by weight of MKP and 50% by weight of silica sand. Compositions 4-3 are 72, 8% by weight MgO strongly calcined at high temperature, 24.2% by weight of MKP and 3% by weight of retardant agent. Dfférents retardants are tested: potassium acetate SGMA Aldrich (4-3a composition), potassium formate VWR (composition

4- 3b) and for comparison the pure boric acid 99.8% Panreac (composition 4-3c). Mixtures of retardant agents were also tested: the 4-3d composition comprises a mixture of 2.40% by weight of potassium formate (VWR) and 0.6% by weight of potassium oxalate (VWR). 4-3e the composition comprises a mixture of 2.40% by weight of potassium acetate (SGMA Aldrich) and 0.6% by weight of oxalate of

potassium (VWR). Other retarders as zi nc formate Alfa Aesar (4-3f composition) and formate calci um VWR (4- composition 3g) were uti ized in an amount of 3% by weight. The amount of water aj outed for mixing is 22% by weight relative to the total amount of pulverulent compounds.

Practical durations uti lisation different compositions were measured and are given in the table below:

Table 3

It is noted that silica sand involved in the retarding effect, but less effective as retardants of the present invention, which allow to obtain a certain effect greater than that which was obtained with retarders such as acid boric used in the prior art.

.Example 5

Similarly, different compositions comprising a ratio MgO: MKP of 25/75 were prepared as in I 'exempl e 4.

5-1 The composition is 25% by weight of MgO strongly calcined at high temperature and 75% by weight of MKP.

5-2 the composition comprises 12.5% ​​by weight of MgO strongly calcined at high temperature, 37.5 wt% of MKP and 50% by weight of silica sand. Compositions 5-3 comprises 24.2% by weight of MgO strongly calcined at high temperature, 72.8% by weight of MKP and 3% by weight of a retarding agent. Different retarders were tested: potassium acetate SGMA Aldrich (composition 5- 3a), potassium oxalate VWR (composition 5-3b) and for comparison the pure boric acid 99.8% Panreac (composition 5-3c). The amount of water added to the mixing is 22% by weight relative to the total amount of pulverulent compounds.

Practical useful lives of the various compositions were measured and are given in the table below:

Composition Composition Composition Composition Composition 5-1 5-2 5- 3a 5- 3b 5- 3c

duration

practice 17 25 80 40 57 of USER

ion (min)

.Example 6

a mixture is prepared (composition 6-1) consisting of:

- 15.8% by weight magnesia strongly calcined at high temperature (1500 ° C) and sintered (Grecian Magnesite)

- 3% by weight of wollastonite CaSO3 (Nordkalk)

- 1% by weight calcined alumina Al 2 Ο½ (RBH)

- 79.2% by weight of potassium dihydrogenphosphate KH 2 PO (Prayon)

- 1% by weight of an inorganic pigment (Oximed Europigments 12A) which allows coloring the sample and visually reveal the presence of efflorescence. The amount of water added is 17% by weight relative to the total amount of pulverulent compounds.

The practice period of application of this paste is 13 min.

The same dough composition is prepared by adding 3% by weight of potassium acetate from Aldrich SGMA (composition 6-2). The practice period of application of this paste is increased and is 40 min.

Figures 1 and 2 show the cured products obtained from these compositions 6-1 and 6-2: one notices the presence of white areas in Figure 1, reflecting the phenomena of efflorescence. In the presence of potassium acetate, the phenomenon of efflorescence is controlled, the color of the sample is more uniform.

example 7

A mixture comprising 52, 6% by weight of lightburned magnesium oxide (ISMAF), 42.1% by weight of potassium dihydrogenphosphate KH 2 PO (Prayon) and 5.3% by weight of retardant, of different types, some of which do not conform to the invention and therefore given for comparison. The amount of water added is 37% by weight relative to the total amount of the pulverulent constituents. Practical periods of use of various pasta products are measured and shown in the table below:

retardant practice Duration of util ization (min)

Formiate potassium um (VWR) 8

Tartrate of potassium di-um (EMS 2

Aldrich)

Benzoate de potassium (Sgma 4

Aldrich)

potassium bromide (Panreac) 5

lodure de potasssium (Panreac) 4

Oéate of potassium (Panreac) 1

Qtrate de calcium (Sgma Aldrich) 0, 5

pure boric acid at 99, 8% (Panreac) 1 1

potassium acetate (Aldrich SGMA) 12

Table 5

For comparison, the same formulation without retarding agent has a practical period of appl ication of 0, 3 min.

.Example 7

A mortar composition is prepared by mixing the various following constituents:

- 40% by weight magnesia strongly calcined at high temperature (1500 ° C) and sintered (Grecian Magnesite)

- 40% by weight of di potassium hydrogen phosphate KH 2 PC¼ (Prayon) - 20% by weight of sand sil ice.

The amount of water aj outed is 20% by weight relative to the total amount of pulverulent compounds.

The practice period of appl ication of this paste is 4, 5 minutes.

The same dough composition is prepared by aj outant 3% by weight of potassium acetate. The practice period of appl ication of this paste is increased and is 32 mi n.

CLAIMS

1. mineral binder based phosphate obtained by reaction between at least one basic component and an acid phosphate salt in the presence of a retarding agent which is a salt X + A " whose aqueous solubility measured at 25 ° Cest higher than that of acid phosphate salt, and wherein

X + is a cation selected from alkali metals, alkaline earth metals, zinc, aluminum and ammonium ion, and

A " is an acetate anion, formate, benzoate, tartrate, oleate, oxalate, bromide or iodide.

2. A binder according to claim 1 characterized in that the basic component is selected from metal oxides, metal hydroxides or sulfates.

3. A binder according to claim 1 characterized in that the basic component is selected from iron oxide, aluminum oxide, zinc oxide, magnesium oxide or calcium oxide, silicates , calcium sulfate sources such as plaster, gypsum, Γ hemihydrate and / or anhydrite, and metallurgical slags.

4. A binder according to one of the preceding claims, characterized in that it is obtained from a mixture of at least two basic components, one of them at least being selected from magnesium oxide , calcium or magnesium hydroxide, wollastonite, alumina, metallurgical slags, and calcium sulfate.

5. A binder according to claim 4 characterized in that said mixture comprises a basic additional component selected from kaolin, metakaolin, calcined clays, fly ash, lime, dolomite, mica and / or talc.

6. A binder according to one of the preceding claims, characterized in that the acid phosphate salt participating in the acid-base reaction forming binder is selected from:

- potassium hydrogen phosphate, calcium, magnesium, aluminum, sodium or ammonium,

- potassium dihydrogenphosphate, calcium, magnesium, aluminum, sodium or ammonium,

- potassium pyrophosphates acids, calcium, magnesium, aluminum, sodium or ammonium, and / or

- potassium acid polyphosphates, calcium, magnesium, aluminum, sodium or ammonium seulsou mixed.

7. A binder according to one of the preceding claims, characterized in that the cation X + of the retarding agent is selected from potassium, calcium, magnesium, sodium, zinc, aluminum or ammonium.

8. A binder according to one of Claims 6 or 7, characterized in that the cation X + of the retarding agent is same as the cation of the acidic phosphate salt involved in the binder forming reaction.

9. A binder according to one of the preceding claims characterized in that the anion A " is an acetate ion or a formate ion.

10. A binder according to one of the preceding claims, characterized in that the retarding agent is a mixture of salts whose anions are selected from acetates, lesformiateset lesoxalates.

11. A binder according to one of the preceding claims characterized in that the retarding agent content is between 1 and 10% by weight, preferably between 2 and 7% by weight, the total amount of the binder components.

12. A binder according Γ one of the preceding claims, characterized in that it comprises another compound selected from phosphate salts of orthophosphates, polyphosphates or pyrophosphates wherein the cation is selected from sodium, potassium, calcium or ammonium ion.

13. A mortar composition or concrete characterized in that it comprises at least one binder according to one of the preceding claims.

14. Products constructions, prepared on site or prefabricated, such as mortars, grouts, tiling joints, tile adhesives, screeds, floor coatings or technical mortars, insulation mortars or façade coatings obtained from the concrete or mortar composition of claim 13.