WO2016156761A1

WO2016156761A1 - Insulating construction material comprising plant additives

Info

Publication number: WO2016156761A1
Application number: PCT/FR2016/050757
Authority: WO
Inventors: Nicolas Perez; Jérôme TIERRIE; Alexandre JACQUEMIN
Original assignee: Lafarge
Priority date: 2015-04-02
Filing date: 2016-04-01
Publication date: 2016-10-06
Also published as: FR3034415A1

Abstract

The invention relates to an insulating construction material with low thermal conductivity, comprising a sulfoaluminate-belite clinker and additives of plant origin, as well as to a method for the production and use of such a material.

Description

INSULATING CONSTRUCTION MATERIAL BASED ON VEGETABLE ADDITIONS

The invention relates to an insulating construction material of low thermal conductivity comprising a belitic sulfoaluminous clinker and additions of plant origin, as well as a method of preparation and uses of such a material. Such a material may be intended for producing prefabricated insulating elements for insulating buildings from the outside or from the inside.

It is known to manufacture insulating elements using plant additives incorporated in a matrix of hydraulic binder, for example based on Portland cement or lime.

However, vegetable additions tend to delay the setting of hydraulic binders. It is therefore necessary to add adjuvants to control the binding of binders, for example trivalent cations.

Thus, the application WO2014 / 072533 describes an insulating construction material comprising plant additions and trivalent cations. It is believed that the addition of trivalent cations accelerates setting time and thus contributes to improved mechanical compressive strength properties. However, the presence of trivalent cations negatively affects the rheology and significantly decreases the initial workability of the hydraulic composition and the workability, which in practice is problematic on construction sites. The material described in WO2014 / 072533 must be self-supporting, the addition of trivalent cations is necessary.

In addition, the addition of trivalent cations increases the total cost of raw materials. In addition, vegetable additives, because of their high demand for water, tend to increase the amount of water required for mixing hydraulic binders. It is therefore also necessary to add adjuvants to control the amount of water added for mixing, for example superabsorbent polymers.

The addition of these additives complicates the formulations used and their implementation, in particular in the case where the hydraulic composition is foamed to obtain a thermal insulating material. Indeed, it is known that it is difficult to produce a hydraulic composition to obtain both good thermal insulation and good mechanical strength, because these two characteristics are contradictory.

Also the problem to be solved by the invention is to provide a new material comprising a plant addition, to ensure a good compromise between thermal conductivity and mechanical resistance and easy implementation. The thermal conductivity is preferably less than 0.15 W / (mK), more preferably less than 0.07 W / (mK) at 23 ° C and 50% relative humidity, the values being obtained by the yarn method. as described hereinafter in the Examples section. The mechanical strengths are preferably greater than 0.05 MPa, more preferably greater than 0.1 MPa 7 days after mixing. The material obtained can then be described as self-supporting and thermal insulation.

Surprisingly, the inventors have demonstrated that it is possible to use a belitic sulfoaluminous clinker mixed with vegetable additives to obtain a material having a good compromise between the thermal conductivity and the mechanical strengths.

For this purpose, the invention relates to a material comprising:

a hydraulic binder comprising a belitic sulfoaluminous clinker and from 0 to

35% of CaSO4 in mass relative to the mass of belitic sulfoaluminous clinker + CaSO 4, the belitic sulphoaluminous clinker comprising, by mass, from 30 to 80% of belite and from 10 to 70% of C4A3 $;

a vegetable addition, the weight ratio vegetable addition in the dry state / hydraulic binder being from 0.05 to 2;

from 0.001 to 2% of a foaming agent, the percentage being expressed in dry mass relative to the mass of mixing water; and

water, the mass ratio total water / hydraulic binder being from 0.7 to 2.5, preferably from 1 to 2;

the material does not include added trivalent cations.

It is understood that the trivalent cations added are different from the trivalent cations that would be naturally present in the components of the material according to the present invention.

Unless otherwise specified, the percentages expressed in this specification and the accompanying claims are exclusive of air.

The material according to the present invention has one or more of the following characteristics:

advantageously, the material according to the invention has a good control of the setting time (the setting time being preferably less than 5 hours, more preferably less than 3 hours) and the rheology of the material (initial workability and workability of the composition hydraulic starting), without the use of trivalent cations or superabsorbent polymers (SAP);

advantageously the material according to the invention can be prepared in a prefabrication plant to produce insulating elements;

- Advantageously the material according to the invention can cure in 24 hours, and at most in 7 days; advantageously the material according to the invention has a rigidity sufficient to support at least its own weight. It is then said to be self-supporting;

advantageously, the material according to the invention has, in the dry-cured state, a low density of from 150 kg / m ³ to 600 kg / m ³ , preferably from 250 kg / m ³ to 500 kg / m ³ ; in some cases the density may even be less than 400 kg / m ³ ;

the incorporation of the biomass in the material according to the invention makes it possible to store the CO ₂ and thus to reduce the impact CO ₂ of the material.

The material according to the invention is made from a belitic sulphoaluminous clinker, a vegetable addition, a foaming agent, water, optionally a viscosifying agent, optionally lime and optionally an accelerator. taking the hydraulic binder.

A hydraulic binder is a material that picks up and hardens by hydration.

Belitic sulfoaluminous clinkers are clinkers having a low alite content, in particular an alite content of less than or equal to 5% by weight, or having no alitis. Alite is one of the "mineralogical phases" (called "phases" in the rest of the description) of known clinkers of the Portland type. The alite comprises tricalcium silicate Ca ₃ SiO ₅ (which may also be symbolized C ₃ S or 3 (CaO) ^" (SiO ₂ ) as explained below).

The process for producing belitic sulfoaluminous clinkers is such that these clinkers have the advantage of significantly reducing CO ₂ emissions compared with the manufacture of known Portland type clinkers.

The chemical formulas in the field of hydraulic binders are often expressed in the form of sums of the oxides they contain: thus, the tricalcium silicate Ca ₃ SiO _5, can also be written 3CaOSiO ₂ . It is understood that this does not mean that the oxides have a proper existence in the hydraulic binder.

The oxide formulas commonly encountered in the field of hydraulic binders are also abbreviated with a single letter, as follows:

C represents CaO,

A represents Al ₂ O ₃ ,

F represents Fe ₂ O ₃ ,

S represents Si0 ₂ ,

$ represents S0 ₃ ,

M represents MgO, and

T represents Ti0 ₂ .

These oxide formulas are used in a manner known to those skilled in the field of building materials to represent the elementary composition. a hydraulic binder, because all the elements concerned are generally present in combination with oxygen in the proportions given above by the formulas of these oxides. Nevertheless, it is understood that this does not mean that the oxides necessarily have a proper existence in the hydraulic binder.

The belitic sulfoaluminous clinker used according to the present invention comprises up to 70% by weight of calcium sulfoaluminate. It comprises at least 10%, preferably at least 15% by weight of calcium sulfoaluminate. Calcium sulfoaluminate, also known as ye'elimite, has a general formula C _{4 to} $ ₃ .

Belitic sulfoaluminous clinker also includes belite. Belite is of general formula C ₂ S. The minimum amount of belite is at least 30%, preferably at least 35% by weight. The maximum amount of belite is at most 80%, preferably at most 75% by weight.

The belitic sulfoaluminous clinker also preferably comprises calcium aluminoferrite. The calcium aluminoferrite has the general formula C2A _x F ₍ i- _X) , wherein x is from 0.2 to 0.8. The amount of calcium aluminoferrite is preferably at least 1%, more preferably at least 5% by weight.

In the case where the belitic sulfoaluminous clinker comprises calcium sulfoaluminate, belite and calcium aluminoferrite, it is a belite-calcium-sulfoaluminate-ferrite clinker (BCSAF).

Preferably, the clinker used according to the present invention is a BCSAF clinker.

The belitic sulfoaluminous clinker preferably comprises, by weight relative to the total mass of belitic sulfoaluminous clinker:

from 5 to 30% calcium aluminoferrite phase;

from 10 to 35% of calcium sulfoaluminate phase; and

from 40 to 75% of belite phase.

Preferably, the belitic sulfoaluminous clinker comprises at most 5%, more preferably less than 1% by weight of an alite phase.

The belitic sulfoaluminous clinker may also comprise from 0.01 to 10% of at least one of the minor phases selected from: calcium sulphate, alkali metal sulphate, perovskite, calcium monoaluminate (for example tricalcium aluminate), gehlenite, free lime, periclase, CnS ₄ B, mayenite, ferroperovskite, spinel, ternesite and / or vitreous phase.

The total percentages of calcium aluminoferrite, calcium sulfoaluminate, belite and minor phases is preferably greater than or equal to about 97%, more preferably greater than or equal to about 98%, even more preferably greater than or equal to about 99%, for example about 100%.

According to one variant, the belitic sulfoaluminous clinker may comprise:

from 10 to 25% calcium aluminoferrite phase; from 15 to 30% of calcium sulfoaluminate phase;

from 45 to 70% belite phase; and

from 0.01 to 5% of at least one of the minor phases.

More preferably, the sulphoaluminous clinker comprises:

from 15 to 25% calcium aluminoferrite phase;

from 20 to 30% of calcium sulfoaluminate phase;

from 45 to 60% belite phase; and

from 0.01 to 5% of at least one of the minor phases.

Pure belite has the general formula 2 (CaO) ^" (Si0 ₂ ), (ie C ₂ S); the pure calcium sulphoaluminate has the general formula 4 (CaO) ^" 3 (Al ₂ O ₃ ) ^" (S0 ₃ ), (ieC ₄ A ₃ $). Belite, calcium sulfoaluminate and the other additional phases of general formulas given above may also include substitution elements.

Each phase cited in the clinker used according to the present invention is crystalline (with the exception of the glassy phase) and has its own X-ray diffraction spectrum. The quantity of the phases in the clinker is generally determined by X-ray diffraction. using a Rietveld type analysis. The glassy phase is not crystalline and therefore does not have a characteristic X-ray diffraction profile. The amount of glassy phase is generally determined from the complete spectrum by X-ray diffraction of the clinker.

The belitic sulfoaluminous clinker used according to the present invention may comprise the C ₂ AS phase (generally less than 5%), CA (generally less than 10%), C ₃ FT (generally less than 3%) and / or Ci ₂ A ₇ (usually less than 3%).

The clinker preferably comprises from 5 to 13%, more preferably from 9 to 13%, of iron expressed as Fe ₂ O ₃ . .

The belitic sulfoaluminous clinker used according to the invention generally comprises from 2 to 10% of sulfur expressed as SO ₃ . Preferably, the sulphoaluminous clinker does not comprise a C ₃ S phase.

The belitic sulfoaluminous clinker used according to the invention comprises, according to a variant, from 0.2 to 3%, more preferably from 0.2 to 2%, for example from 1 to 2%, boron expressed as boric anhydride.

Preferably, the belitic sulfoaluminous clinker used according to the invention does not comprise boron.

The clinker used according to the present invention may comprise, in the main phases and / or in the other phases, one or more of the secondary elements chosen from sodium, potassium, fluorine, chlorine, magnesium, titanium and manganese. , strontium, zirconium, phosphorus and mixtures thereof. The total amount of secondary elements in the sulfoaluminous clinker is preferably lower or equal to 19%, more preferably less than or equal to 15%, expressed as equivalent oxides.

In the belitic sulfoaluminous clinker used according to the present invention, the secondary element is generally present in the following amounts:

from 0 to 5%, preferably from 0.01 to 2%, more preferably from 0.02 to 1.5%, for example from 0.02 to 1% of sodium, expressed as sodium oxide equivalent,

from 0 to 5%, preferably from 0.1 to 2%, more preferably from 0.2 to 1.5%, for example from 0.2 to 1% of potassium, expressed as potassium oxide equivalent,

from 0 to 7%, preferably from 0 to 5%, more preferably from 0 to 3% of phosphorus expressed as phosphorus pentoxide equivalent.

According to one variant, the belitic sulfoaluminous clinker used according to the present invention may comprise as main phases, in% expressed by weight relative to the total mass of clinker:

(i) from 15 to 36% of a belite phase;

(ii) from 37 to 56% of a calcium sulfoaluminate phase;

and

(iii) from 1 to 28% of a ferroperovskite phase, comprising calcium, aluminum, silicon, magnesium and iron, and characterized by X-ray diffraction peaks (2-theta) at 33, 2 °, 47.7 ° and 59.4 ° using CuKc 'X-rays having a wavelength of 0.15406 nm;

clinker comprising: from 3 to 15% iron expressed as Fe ₂ O ₃ ; and from 0.2 to 5% boron expressed as boric anhydride.

According to another variant, the belitic sulfoaluminous clinker used according to the present invention can comprise as main phases, in% expressed by weight relative to the total mass of clinker:

(i) from 36 to 53% of a calcium sulfoaluminate phase; and

(ii) from 31 to 50% of a belite phase;

the clinker comprising: less than 3% iron expressed as Fe ₂ O ₃ ; and from 0.2 to 5% boron expressed as boric anhydride.

The belitic sulfoaluminous clinker may for example be obtained according to the process described in the patent application WO 2006/018569.

The belitic sulfoaluminous clinker may also be produced by a process which comprises clinkering, preferably at a temperature of 1150 ° C. to 1400 ° C., more preferably from 1200 ° C. to 1325 ° C., sources of calcium, silicon and sulfur. , alumina, magnesium, iron and boron capable, by clinkering, of providing the phases as described above.

The belitic sulfoaluminous clinker according to the invention can for example be produced in the following manner: a) preparing a raw material comprising a raw material or a mixture of raw materials capable, by clinkering, of providing the phases as described above; b) mixing the raw material obtained in step a) with at least one additive providing a secondary element as mentioned above, in amounts such that, after clinkering, the total amount of secondary elements, expressed as indicated above, is less than or equal to 19% by weight relative to the total mass of belitic sulfoaluminous clinker; and

c) calcining the mixture obtained in step b), for example, at a temperature of 1150 ° C to 1400 ° C, preferably 1200 ° C to 1325 ° C, for example for at least 15 minutes in a sufficiently atmosphere oxidant to prevent the reduction of calcium sulphate to sulfur dioxide.

Preferably, the raw materials which may be suitable for carrying out step a) of the process described above may come from quarries or result from an industrial process and comprise:

a source of silicon, for example sand, clay, marl, fly ash, coal combustion ash, pozzolan or silica fume;

a source of calcium, for example limestone, marl, fly ash, coal combustion ash, slag, pozzolana or household waste calcining residues;

a source of alumina, for example a clay, a marl, fly ash, coal combustion ash, a pozzolan, a bauxite, a red alumina sludge (in particular a sludge of alumina from industrial waste during alumina extraction), laterite, anorthosite, albite or feldspar;

a source of sulfur;

a source of magnesium;

a source of iron, for example iron oxide, laterite, steelmaking slag or iron ore; and

a source of boron.

The source of boron may include, for example, colemanite (di-calcium hexaborate pentahydrate), borax or boric acid, preferably colemanite. The source of boron can come from quarries or result from an industrial process.

The raw material may also comprise calcium sulphate, for example gypsum, calcium sulphate hemihydrate (α or β) or anhydrous calcium sulphate.

The preparation of the raw material of step a) can be carried out by mixing the raw materials. The raw materials may be mixed in step a) by contacting, possibly comprising a grinding and / or homogenization step. The The raw materials of step a) may optionally be dried before step a) or calcined before step a).

The raw materials can be added sequentially, in the main oven inlet, and / or in other oven inlets. In addition, the combustion residues can also be integrated in the oven.

Preferably, the raw materials that may be suitable for carrying out step b) of the process described above are:

a source of boron, for example borax, boric acid, colemanite or any other compound containing boron: the source of boron may come from a quarry or result from an industrial process;

a source of magnesium, for example a magnesium salt;

a source of sodium, for example a sodium salt;

a source of potassium, for example a potassium salt;

a source of phosphorus, for example a phosphorus salt;

or their mixtures.

The raw materials that may be suitable for carrying out step b) are in the form of a solid (for example powder), a semi-solid or a liquid.

Step c) is a clinkerization step, which means, within the meaning of the invention, a cooking step. By clinkerization is meant in the sense of the invention the reaction between the chemical elements of step b) which leads to the formation of sulfoaluminous clinker phases according to the present invention. This step may be carried out in a conventional cement kiln (for example a rotary kiln) or in another type of kiln (for example a kiln).

For a sufficiently oxidizing atmosphere is meant for example atmospheric air, but other atmospheres sufficiently oxidizing may be suitable.

A hydraulic binder is a material that picks up and hardens by hydration. A hydraulic binder generally comprises a clinker, calcium sulphate and optionally a mineral addition.

A belitic sulfoaluminous clinker can be co-milled with calcium sulfate to give a cement. The calcium sulphate used includes gypsum (calcium sulphate dihydrate, CaSO ₄ .2H ₂ O), hemihydrate (CaSO ₄ .1 / 2H ₂ O), anhydrite (anhydrous calcium sulphate, CaSO ₄ ) or one of their mixtures. Gypsum and anhydrite exist in their natural state. It is also possible to use a calcium sulphate which is a by-product of certain industrial processes.

Preferably, the material according to the present invention comprises from 5 to 32% by weight of calcium sulphate relative to the mass of belitic sulphoaluminous clinker + CaSO ₄ . Preferably, the hydraulic binder comprises another type of clinker, for example a Portland clinker. A Portland clinker is obtained by high temperature clinkerisation of a mixture comprising in particular limestone and clay.

Preferably, the amount of Portland clinker is from 0 to less than 50%, more preferably from 0 to 25%, even more preferably from 0 to 15% by weight relative to the total weight of hydraulic binder. Preferably, the remainder of the hydraulic binder is a belitic sulfoaluminous binder.

The material according to the invention is produced with vegetable additions.

Vegetable additives are plant-based materials or crushed vegetable waste.

It can be natural materials or aggregates porous natural and rich in organic matter (cellulose, hemicelluloses, lignins ...). from plants via industrial manufacturing processes (shredding, crushing, grinding, separation).

Examples of vegetable additions include rapeseed straw, hempwood (hempwood) granules, maize stalks, sorghum straws, flax shives, miscanthus (elephant grass), rice husks, cane bagasse, cereal straw, sunflower straw, maize straw, kenaf, coconut, olive kernels, bamboo, wood pellets (eg shredded spruce), wood chips and mixtures thereof.

Preferably, the vegetable addition may be chenevot, rapeseed straws, rice balls or sunflower straws.

Plant additions that are suitable for the material according to the invention can be treated so as to reduce their water absorption capacities and their release capacities of water-soluble organic substances (products potentially retarding the setting of the hydraulic binder) in water or in the cementitious medium, by different techniques:

- leaching in water at neutral or basic pH at a temperature ranging from 20 to 100 ° C,

- polymerization of the water-soluble organic substances of the biomass either by heat treatment (crosslinking, pyrolysis) at high temperature (from 80 to 220

° C), either by ionization or plasma or UV treatment.

For example, the vegetable addition can be charcoal derived from the pyrolysis of biomass.

For example, the treated vegetable additives may have been mixed or sprayed with a compound which confers on them a particular property, in particular hydrophobic properties. For example, a water-repellent treatment with hydrocarbons, silicones, latices, vegetable oils, fatty alcohols, fatty acids or mixtures thereof. The water-repellent treatment can be a fixation of (C2 to C30) alkyl groups on the OH group of the biomass by esterification and / or etherification.

According to one variant, the material according to the invention comprises at least one treated vegetable addition. According to another variant, all the vegetable addition used according to the present invention is treated.

Preferably, the material according to the invention comprises a vegetable addition amount of 10 to 1000 liters apparent per m ³ of material.

Preferably, the material according to the invention has a mass ratio dry vegetable additive / hydraulic binder expressed in mass of 0.04 to 1, 9.

Preferably, when the vegetable addition is not retted, the material according to the present invention further comprises a setting accelerator of the hydraulic binder.

The material according to the invention is produced using a foaming agent.

The foaming agent used according to the invention may be chosen from ionic, anionic, nonionic, amphiphilic or amphoteric foaming agents and used alone or in mixtures.

As ionic surfactants, non-limiting mention may be made of alkyl ether sulfonates, hydroxyalkyl ether sulfonates, alpha-olefin sulphonates, alkyl benzene sulphonates, alkyl sulphonate esters, alkyl ether sulphates, hydroxy alkyl ether sulphates, alpha olefin sulphates, alkyl benzene sulphates and alkyl sulphate amides, as well as their alkoxylated derivatives (especially ethoxylated (EO) and / or propoxylated (OP)), the corresponding salts or their mixtures.

As ionic surfactants, mention may also be made, in a nonlimiting manner, of saturated or unsaturated fatty acid salts and / or their alkoxylated derivatives in particular (OE) and / or (OP) (for example sodium laurate, palmitate). of sodium or sodium stearate, sodium oleate), sulphonated methyl and / or sodium laureate derivatives, alkylglycerol sulphonates, sulphonated polycarboxylic acids, paraffin sulphonates, N-acyl N-alkyltaurates, alkylphosphates, alkylsuccinamates, alkylsulfosuccinates, sulfosuccinate monoesters or diesters, alkylglucoside sulfates.

Nonionic surfactants that may be mentioned in a nonlimiting manner include ethoxylated fatty alcohols, alkoxylated alkylphenols (especially (EO) and / or (OP)), aliphatic alcohols, more particularly C8-C22 alcohols, products resulting from the condensation of ethylene oxide or propylene oxide with propylene glycol or ethylene glycol, the products resulting from the condensation of ethylene oxide or propylene oxide with ethylene diamine alkoxylated fatty acid amides (especially (EO) and / or (OP)), alkoxylated amines (especially (EO) and / or (OP)), alkoxylated amidoamines (in particular (EO) and / or (OP)). )), the amine oxides, the alkoxylated terpene hydrocarbons (especially (EO) and / or (OP)), the alkylpolyglucosides, the amphiphilic polymers or oligomers, ethoxylated alcohols, sorbitan esters or ethoxylated sorbitan esters.

As amphoteric surfactants, mention may be made, without limitation, of betaines, imidazoline derivatives, polypeptides or lipoamino acids. More particularly, the betaines that are suitable according to the invention can be chosen from cocamidopropyl betaine, dodecyl betaine, hexadecyl betaine, octadecyl betaine, phospholipids and their derivatives, amino acid esters, water-soluble proteins, water-soluble proteins and mixtures thereof.

As cationic surfactants, mention may also be made, without limitation, of the oxide of amino laurate, the oxide of amino propyl cocoate, the caprylamphocarboxy glycinate, the lauryl propionate, the lauryl of betaine, the talloil bis 2- Betaine hydroxyethyl.

According to a particular embodiment of the invention, the nonionic foaming agent may be associated with at least one anionic or cationic or amphoteric foaming agent.

As amphiphilic surfactants, mention may be made, without limitation, of polymers, oligomers or copolymers which are at least miscible in the aqueous phase.

The amphiphilic polymers or oligomers may have a statistical distribution or a multiblock distribution.

The amphiphilic polymers or oligomers used according to the invention are chosen from block polymers comprising at least one hydrophilic block and at least one hydrophobic block, the hydrophilic block being obtained from at least one nonionic and / or anionic monomer.

By way of example of such amphiphilic polymers or oligomers, mention may in particular be made of polysaccharides having hydrophobic groups, in particular alkyl groups, polyethylene glycol and its derivatives.

As examples of amphiphilic polymers or oligomers, mention may also be made of polyhydroxystearate-polyethylene glycol-polyhydroxystearate triblock polymers, branched or unbranched acrylic polymers, or hydrophobic polyacrylamide polymers.

With regard to the nonionic amphiphilic polymers more particularly alkoxylated (in particular (EO) and / or (OP)), the latter are more particularly chosen from polymers of which at least a part (at least 50% by mass) is miscible in water.

By way of examples of polymers of this type, mention may be made, inter alia, of polyethylene glycol / polypropylene glycol / polyethylene glycol triblock polymers.

Preferably, the foaming agent used according to the invention is a protein, in particular a protein of animal origin, more particularly keratin, or a protein of plant origin, more particularly a water-soluble protein of wheat, rice, soy or cereal. By way of example, mention may be made of hydrolyzate sodium laurate of wheat protein, oat protein hydrolyzate laurate, or apple amino acid cocoate.

Preferably, the foaming agent used according to the invention is a protein whose molecular weight is between 300 and 50,000 Daltons.

The foaming agent is used according to the invention at a content of 0.001 to 2%, preferably 0.01 to 1%, more preferably 0.05 to 0.2% by weight of foaming agent relative to mass of mixing water.

Preferably, the material according to the invention comprises from 0.01 to 0.1% of a foaming agent, percentage by weight relative to the mass of mixing water.

Preferably, the material according to the present invention does not comprise a water-retaining agent, for example a superabsorbent polymer.

Preferably, the material according to the present invention does not comprise CaCO ₃ calcium carbonate.

The material according to the present invention may also comprise a viscosity agent. The viscosing agent may for example be chosen from carob, guar gum, tragacanth, arabic, xanthan, diutane, Tara (carob from Peru) gum, cellulose, scleroglucan, gelatin, pectin, alginate, carrageenans, corn starch, potato amylopectin, cellulose ethers and mixtures thereof.

Preferably, the viscosing agent is chosen from cellulose ethers, in particular methylcellulose, ethylmethylcellulose, hydroxymethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose and mixtures thereof.

The amount of viscosity agent is preferably less than or equal to 0.55%, more preferably less than or equal to 0.5%, by dry weight relative to the weight of hydraulic binder.

Without being bound by the theory, it seems that the viscosity agent makes it possible to stabilize the air bubbles and thus to maintain the density.

The material according to the present invention may also comprise lime, for example hydrated, overcured or bright.

The amount of lime is less than or equal to 5%, more preferably less than or equal to 4% by weight relative to the weight of hydraulic binder.

Without being bound by the theory, it seems that the hydrated lime makes it possible to improve the mechanical resistances.

The material according to the invention may optionally comprise an accelerator for the setting of the hydraulic binder, preferably from 0.01 to 5%, the percentage being expressed in dry mass relative to the weight of hydraulic binder. The accelerator for the setting of the hydraulic binder of the material according to the invention may be chosen from calcium chloride, calcium nitrite, calcium nitrate, lithium carbonate, lithium chloride and lithium hydroxide. lithium nitrite, lithium nitrate, lithium sulphate and mixtures thereof.

The material according to the invention optionally comprises at least one superplasticizer. Preferably, the superplasticizer / hydraulic binder mass ratio is between 0.001 and 0.02 by dry weight.

The term "superplasticizer" as used in the present specification and accompanying claims is to be understood to include both water reducers and superplasticizers as described in the book entitled "Concrete Admixtures Handbook, Properties Science". and Technology, "VS Ramachandran, Noyes Publications, 1984.

A water reducer is defined as an adjuvant which typically reduces the amount of mixing water of a concrete by 10 to 15% for a given workability. Water reducers include, for example, lignosulfonates, hydroxycarboxylic acids, carbohydrates and other specialized organic compounds, for example glycerol, polyvinyl alcohol, sodium alumino-methyl-siliconate, sulfanilic acid and casein.

Superplasticizers belong to a new class of water reducers, chemically different from normal water reducers and able to reduce water amounts by about 30%. Superplasticizers were broadly classified into four groups: sulfonated condensates of naphthalene formaldehyde (SNF) (usually a sodium salt); sulphonated condensates of melamine formaldehyde (SMF); modified lignosulfonates (MLS); And the others. More recent superplasticizers include polycarboxylic compounds such as polycarboxylates, for example polyacrylates. A superplasticizer is preferably a new generation superplasticizer, for example a copolymer containing a polyethylene glycol as grafted chain and carboxylic functions in the main chain as a polycarboxylic ether (PCP). It may be a deferred PCP. Sodium polycarboxylate polysulfonates and sodium polyacrylates can also be used. Phosphonic acid derivatives can also be used. The required amount of superplasticizer usually depends on the reactivity of the cement. The lower the reactivity, the lower the required amount of superplasticizer.

The hydraulic binder used according to the invention may optionally comprise mineral additions.

Mineral additions are generally materials that can be used as partial substitution for cement.

The mineral additions suitable for the material according to the invention may be chosen from slags (for example as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.2), natural or artificial pozzolans (for example as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.3), fly ash (for example as defined in the standard NF EN 197-1 of February 2001, paragraph 5.2.4), calcined schists (for example as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.5), mineral additions based on carbonate of calcium, for example limestone (for example as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.6), silica fumes (for example as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.7), metakaolin, biomass ash (eg rice husk ash) or mixtures thereof.

The mineral additions used according to the invention may also be ash from the combustion of plants, such as for example the ashes from the combustion of rice balls.

The mineral additions used according to the invention may also be zeolites.

Flying ash is usually a powdery particle in the flue gases of coal-fired power plants. It is usually recovered by electrostatic or mechanical precipitation.

The chemical composition of a fly ash depends mainly on the chemical composition of the burned coal and the process used in the thermal power plant from which it originated. It is the same for its mineralogical composition. The fly ash used according to the invention may be of siliceous or calcic nature.

Preferably, the fly ash used according to the present invention is chosen from those as described in European Standard NF EN 197-1 of February 2001.

Slags are generally obtained by rapidly cooling the molten slag from the smelting of iron ore in a blast furnace.

The slags used according to the present invention may be chosen from granulated blast furnace slags according to the European Standard NF EN 197-1 of February 2001, paragraph 5.2.2.

The silica fumes used according to the present invention may be a material obtained by the reduction of high purity quartz by charcoal in electric arc furnaces used for the production of silicon and ferrosilicon alloys. The silica fumes are generally formed of spherical particles comprising at least 85% by mass of amorphous silica.

Preferably, the silica fumes used according to the present invention may be chosen from silica fumes according to European Standard NF EN 197-1 of February 2001, paragraph 5.2.7. The pozzolanic materials used according to the present invention may be natural siliceous or silico-aluminous substances, or a combination thereof. Pozzolanic materials include natural pozzolans, which are generally materials of volcanic origin or sedimentary rocks, and calcined natural pozzolans, which are materials of volcanic origin, clays, shales or rocks. sedimentary, thermally activated. The pozzolanic materials used according to the invention may be chosen from pumice, tuffs, slag or mixtures thereof.

Preferably, the pozzolanic materials used according to the present invention may be chosen from pozzolanic materials according to the European standard NF EN 197-1 of February 2001, paragraph 5.2.3.

Preferably, the mineral additions used according to the invention may be materials containing calcium carbonate, for example limestone and / or fly ash and / or silica fumes.

Preferably, the mineral additions used according to the invention may be fines of silica and / or limestone filler.

The calcined clays used according to the present invention can result from the calcination of a clay, kaolinite, associated with different minerals (phyllosilicates, quartz, iron oxides) in varying proportions depending on the deposits. They can be obtained either by grinding calcination or by grinding calcination in production units with rotary kilns, trays or so-called "flash" calcination, for example. They are essentially composed of amorphous alumina silicate particles.

Preferably, the calcined clays used according to the present invention may be chosen from metakaolins according to the preliminary draft standard PR NF P 18-513 of December 201 1.

Preferably, the material according to the invention has a mass ratio total water (pre-wetting + mixing) / hydraulic binder from 0.8 to 2.4.

The materials according to the invention combine a sufficiently high compressive strength with a reduced thermal conductivity compared to those concretes usually available in the field. The compressive strength is generally 0.1 to 1.5 MPa at 7 days. Moreover these formulations are simple and easy to implement. Finally the constituents used are relatively low cost and readily available. This makes these formulations particularly useful in the industry.

Preferably, the material according to the invention has a thermal conductivity at 23 ° C. and 50% relative humidity less than 0.15 W / mK, preferentially less than 0.1 W / mK, and even more preferably less than 0 , 07 W / mK

Thermal conductivity (also called lambda (λ)) is a physical quantity that characterizes the behavior of materials during conductive heat transfer. Thermal conductivity is the amount of heat transferred per unit area and a unit of time under a temperature gradient. In the international system of units, thermal conductivity is expressed in watts per meter kelvin (W / mK). Ordinary concretes have a thermal conductivity at 23 ° C and 50% relative humidity from 1.3 to 2.1 W / (mK). Traditional lightweight concretes have thermal conductivities generally greater than 0.8 W / (mK) at 23 ° C and 50% relative humidity.

The thermal conductivity can for example be determined by the hot plate method or by the hot wire method. In the present description and the accompanying claims, the thermal conductivity was measured according to the hot wire method (as described in the Examples section). It should be noted that, generally, the hot plate method gives lower thermal conductivity results than those obtained by the hot wire method.

The invention also relates to a method for preparing a material according to the invention, this process comprising mixing the hydraulic binder, the vegetable addition, the foaming agent and water, in the proportions such that defined above, in the absence of added trivalent cations. The hydraulic binder, the vegetable addition, the foaming agent and the water are as defined above.

Preferably, the method of manufacturing a material according to the invention comprises: a first step of pre-wetting the vegetable addition,

a second mixing step between the prewet vegetable addition, the hydraulic binder and the mixing water containing the foaming agent. Any other additives (viscous agent, lime, setting accelerator, etc.) can also be added together with the mixing water.

In this pre-wetting step, water (pre-wetting water) is mixed with the vegetable addition before the second step.

According to a variant of the method according to the invention, it is possible to add a third curing step of the material obtained. For example, the material can be maintained in an atmosphere whose residual humidity varies from 60 to 100% for a few hours to several days.

According to another embodiment of the method according to the present invention, it is possible to add each of the constituents mentioned above separately.

The material according to the present invention can be shaped to produce, after hydration and hardening, a shaped object for the field of construction. The invention also relates to such a shaped object which comprises the material as described above. Objects formatted for the field of construction include, for example, a block or panel.

In the present description, including the accompanying claims, the percentages are by weight, unless otherwise specified. The material according to the present invention can be either shaped, projected or cast.

The invention also relates to the use of a material according to the invention as an insulating building material.

The Dv90 is the 90 ^th percentile of the distribution of particle size, by volume, that is to say that 90% of particles have a size less than or equal to the Dv90 and 10% of the particles have a size larger than the Dv90.

The following examples are non-limiting and illustrate the invention. EXAMPLES

Determination of fresh density (MVH):

The density of the material in the fresh state was determined, immediately after mixing, according to the European standard NF EN 12350-6 of December 1999, but in a container whose volume was 1 liter.

Determination of the density of dry cured material (MVS):

The density of the cured material in the dry state was determined 7 days after mixing on 10 cm x 10 cm x 10 cm blocks dried at 45 ° C to constant mass. The cube, whose volume is known, was weighed.

Determination of compressive strength (Rc):

The compressive strength measurements were carried out on cubes of 10 cm x 10 cm x 10 cm according to the European standard NF EN 12390-3 of February 2003. The mechanical strength of the cubes of material was measured at the deadlines of 24 hours and 7 days using a ZWICK press.

Determination of the thermal conductivity (A):

Thermal conductivity was determined by the hot wire method on 10 cm x 10 cm x 10 cm cubes cut in half and dried to a constant mass at 45 ° C. Before the measurement, the cubes cut in half and dried were stored overnight in an airtight bag at room temperature. The measurement was made at 23 ° C. and 50% relative humidity by placing the probe of a CT meter between the two parts of the cube stacked vertically one above the other.

Determination of slump

The slump measurements were performed using a truncated cone, corresponding to a ½ scale reproduction of the cone as defined by the NF P 18-451 standard of 1981. The truncated cone had the following dimensions :

- diameter of the upper base: 50 +/- 0.5 mm;

diameter of the lower base: 100 +/- 0.5 mm; and

height: 150 +/- 0.5 mm. The slump measurements were performed according to the protocol as described below:

fill the truncated cone at one time with the material to be tested; prick if necessary to distribute the material homogeneously in the truncated cone;

level the top surface of the cone;

lift the truncated cone vertically; and

measure sagging of the material at +/- 1 mm at the highest point.

List of raw materials:

Belitic sulphoaluminous cements were:

SAB-1 cement: cement having a Blaine specific surface area of about 3720 cm ² / g, a Dv90 of about 55.65 μηη and comprising 78% of clinker and 22% of gypsum, the clinker having the following characteristics (percentages

Loss on fire: 0.91%

The total is not necessarily equal to 100%, because of impurities that do not appear in this table and inaccuracies inherent in the methods of measurement and determination.

SAB-2 cement: cement having a Blaine surface area of about 6000 cm ² / g and comprising 68% clinker and 32% gypsum, the clinker having the following characteristics (mass percentages):

SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO K ₂ O Na ₂ O

12, 13 27.34 5.33 45.67 0.39 0.20 0.02 so ₃ Ti0 ₂ Mn ₂ 0 ₃ P2O5 Cr ₂ 0 ₃ Zr0 ₂ SrO

7.70 1, 0.03 0.03 0.03 0.04 0.29 Brown- Ferro-

Ye'elimite Belite Ferrite MgAlo, ₂ Fe _{1 8} 0 ₄ Periclase

perovskite millerite

55.5 31.7 1, 80 1, 87 8.47 0.51 0, 1 1

Loss on fire: 0,29%

SAB-3 cement: cement having a Blaine specific surface area of approximately 6810 cm ² / g, a Dv90 of approximately 37.14 μηη and comprising 78% of clinker and 22% of gypsum, the clinker having the following characteristics (percentages by weight ):

Loss on fire: 1, 01%

The Portland cement was a CEM I 52.5 R cement having a density of about 3140 kg / m ³ , a Blaine specific surface area of about 3870 cm ² / g and a Dv 90 of about 35.31 μηη. This cement was of type CEM I, of resistance class 52.5 coming from the factory Lafarge du Teil and had the following characteristics (percentages mass):

SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO K ₂ O Na ₂ O

20.45 4.79 2.48 65.35 0.99 0, 1 1 0, 12

S0 ₃ Ti0 ₂ Mn ₂ 0 ₃ P2O5 Cr ₂ 0 ₃ Zr0 ₂ SrO

3.51 0.21 0.03 0.07 0.04 0, 17 Aluminate

Alite Belite Ferrite Calcite Lime Periclase Calcium

62.6 17.0 8.2 1, 3 0.4 5.8 0.3

Semi-

Anhydrite Gypsum

hydrate

2, 1 0.6 1, 6

Loss on fire: 1, 46%

The hydrated lime (Ca (OH) ₂ ) was supplied by Baltazar and Cotte and had a BET specific surface area of 1.17 m ² / g and a Dv90 of 54.28 μηι.

The foaming agent was either:

sodium dodecyl sulfate 95% purity provided by VWR and dissolved in 6% solids;

cocamidopropyl betaine supplied by Stepan under the name Amphosol CGUN at 33.23% dry extract.

The viscosifier was a cellulosic derivative provided by Dow Chemical under the name Methocel A4M in powder form.

The setting accelerator for belitic sulfoaluminous cement was lithium carbonate (Li ₂ CO ₃ ) supplied by Sigma Aldrich in powder form.

The vegetable addition was either:

Chenevotte non rouy provided by the company Chanvrière de l'Aube. Its water content was 12.3% (percentage by mass), and its bulk density was 150 kg / m ³ ;

Viet Nam's rice husk provided by Cotrada. Its water content was 10% (percentage by mass) and its bulk density was 136 kg / m ³ ;

of the milled stem of red rapeseed supplied by Fibre Recherche Développement. Its water content was 15% (percentage by mass) and its bulk density was 87 kg / m ³ ;

crushed unroasted rapeseed stem supplied by Fibre Recherche Développement. Its water content was 12.5% (percentage by mass) and its bulk density was 106 kg / m ³ ; crushed sunflower stem supplied by Fibre Recherche Développement. Its water content was 15.2% (mass percentage) and its density was 132 kg / m ³ .

Tempered control materials or according to the invention were prepared using a kneader supplied by the company VMI Rayneri (Model PH602, No. 121025, stainless steel bowl 30 liters, planetary movement) in a room thermostated at 20 ° C, according to the following procedure:

introducing the vegetable addition and the pre-wetting water into the kneader;

knead the mixture continuously for 10 minutes at a speed of 26 rpm;

introduce the hydraulic binder into the mixer (= T0) then knead for 1 minute at a speed of 26 rpm;

introducing the mixing water comprising the foaming agent into the kneader and kneading for 5 minutes at a speed of 26 rpm;

stop the mixing, measure the density and the slump of the fresh material; pour the rest of the dough into 10 cm x 10 cm x 10 cm cubic polystyrene molds, and keep the cubes in their molds at 20 ° C and 100% relative humidity.

In the various examples below, the values in the tables are expressed in grams, except when another unit is explicitly mentioned.

Example 1: Tests with different vegetable additions

Several materials according to the present invention have been made, with different types of plant addition: rapeseed, rice husk, sunflower and hemp. The formulations and results are shown in Table 1 below.

Table 1: Tests with different vegetable additions

According to Table 1 above, the different materials according to the present invention have made it possible to achieve, with the various vegetable additions tested, a good compromise between the thermal conductivity (less than 0.15 W / mK, or even less than 0.07 W / mK) and compressive strength 7 days after mixing (greater than 0.05 MPa and even greater than 0.1 MPa).

The delta MVH between the first and the last cube showed the stability of the foam obtained. This delta corresponds to the difference in MVH between the different cubes that were cast from the same formulation.

Example 2 Tests with Different Hydraulic Binders

Several materials according to the present invention have been made, with different types of hydraulic binder: two belitic sulfoaluminous cements (SAB-1 and SAB-2) and several mixtures of cement SAB-1 and Portiand cement. A control was carried out comprising 50% Portiand cement in mass relative to the SAB-1 cement mass. The formulations and results are shown in Table 2 below.

From Table 2 above, the different materials according to the present invention have made it possible to achieve, with the various hydraulic binders tested, a good compromise between the thermal conductivity (less than 0.15 W / mK, or even less than 0.07 W / mK) and compressive strength 7 days after mixing (greater than 0.05 MPa and even greater than 0.1 MPa).

The delta MVH between the first and the last cube showed the stability of the foam obtained.

Example 3 Tests with Different Quantities of Viscosity Agent

Several materials according to the present invention have been made with different amounts of viscosity agent: 0%, 0.2%, 0.3% and 0.45%, by weight relative to the weight of hydraulic binder. A control was made comprising 0.6% viscosifier. The formulations and results are shown in Table 3 below.

Table 3: Tests with different amounts of viscosity agent

M3-1 M3-2 M3-3 M3-4 Witness

0% / binder 0.2% / binder 0.3% / binder 0.45% / binder 0.6% / binder

Rice ball 330.0 330.0 330.0 330.0 330.0

Water of

420.0 420.0 420.0 420.0 420.0 prewetting

SAB-3 1200 1200 1200 1200 1200

Methocel A4M 0.0 2.4 3.6 5.4 7.2

Amphosol

3.61 3.62 3.62 3.62 3.62 CGUN

Li ₂ C0 ₃ 0.24 0.24 0.24 0.24 0.24

Water of

477.6 478.5 479.0 479.7 480.5 mixing

Slump (mm) 100 100 100 80 0

MVH (kg / m ³ ) 677,596 537,726 1057

Rc 24h (MPa) 0.67 0.35 0.27 0.98

Rc 7j (MPa) 1, 07 0.65 0.53 1, 45

λ (W / (m.K)) 0.145 0.1 15 0.1 1 1 0.134

MVS 7j (kg / m ³ ) 601 470 423 551 Too

Delta MVH viscous between 1 st and

109 26 29 19

last cube

(kg / m ³ ) According to Table 3 above, the different materials according to the present invention have made it possible to achieve, with the various amounts of viscosity agent tested, a good compromise between the thermal conductivity (less than 0.15 W / mK). and the compressive strength 7 days after mixing (greater than 0.05 MPa and even greater than 0.1 MPa).

The delta MVH between the first and the last cube has shown better stability of the foam in the presence of viscosity agent.

Example 4 Tests with Different Quantities of Hydrated Lime

Several materials according to the present invention have been made with different amounts of hydrated lime: 1%, 3% and 5% by weight relative to the weight of hydraulic binder. The formulations and results are shown in Table 4 below.

Table 4: Tests with different amounts of hydrated lime

From Table 4 above, the different materials according to the present invention have made it possible to achieve, with the various amounts of lime tested, a good compromise between the thermal conductivity (less than 0.15 W / mK) and the compressive strength 7 days after mixing (greater than 0.05 MPa).

Claims

Material comprising:

a hydraulic binder comprising a belitic sulphoaluminous clinker and from 0 to 35% of CaSO ₄ by weight relative to the mass of belitic sulphoaluminous clinker + CaSO ₄ , the belitic sulphoaluminous clinker comprising, by weight, from 30 to 80% of belite and from 10 to 70% C4A3 $;

a vegetable addition, the mass ratio of vegetable additive in the dry state / hydraulic binder being from 0.05 to 2;

water, the mass ratio total water / hydraulic binder being from 0.7 to 2.5;

the material does not include added trivalent cations.

The material of claim 1, wherein the clinker is a belite-calcium-sulfoaluminate-ferrite clinker.

Material according to claim 1 or 2, wherein the hydraulic binder further comprises less than 50% by weight of a clinker or Portland cement, based on the total weight of hydraulic binder.

Material according to any one of the preceding claims, comprising a vegetable addition chosen from rapeseed straws, chenevotte granules (hemp), maize cobs, sorghum, flax shives, miscanthus (elephant grass), rice husks (rice husks), cane bagasse, cereal straw, sunflower straw, corn straw, kenaf, coconut, olive kernels, bamboo, wood pellets , wood chips and their mixtures.

Material according to any one of the preceding claims, further comprising a viscosity agent.

6. Material according to any one of the preceding claims comprising lime.

7. Material according to any one of the preceding claims, comprising a setting accelerator of the hydraulic binder.

8. Process for the preparation of a material according to any one of claims 1 to 7, this process comprising mixing the hydraulic binder, the vegetable addition, the foaming agent and water, in the absence of trivalent cations added.

The method of claim 8 comprising:

a first step of pre-wetting of the vegetable addition;

a second mixing step between the prewet vegetable addition, the hydraulic binder and the mixing water containing the foaming agent.

10. Use of a material according to any one of claims 1 to 7 as insulating building material.

1 1. A shaped object comprising the material of any one of claims 1 to 7.