WO2017178729A1

WO2017178729A1 - Highly lightweight and thermally insulating mortar composition

Info

Publication number: WO2017178729A1
Application number: PCT/FR2017/050781
Authority: WO
Inventors: Daniel Comoy; Michaël PERRAT DIT GENTON
Original assignee: Saint-Gobain Weber
Priority date: 2016-04-13
Filing date: 2017-04-04
Publication date: 2017-10-19
Also published as: AR108126A1; BR112018068834A2; FR3050203B1; EP3442929A1; FR3050203A1

Abstract

The present invention relates to a thermally insulating mortar composition devoid of siliceous, calcareous and/or siliceous/calcareous aggregates with a particle size of greater than 100 µm and comprising a mixture of at least: - 40% of inorganic lightening fillers, the bulk density of which is less than 200 kg/m³, - an inorganic binder chosen from sulfoaluminate cements, high-alumina cements and/or binary or ternary binders comprising at least one high-alumina or sulfoaluminate cement, - an air-entraining agent of surfactant type chosen from organic fatty acids, sulfate compounds, sulfonate compounds and/or natural wood resins, and - a viscosifying agent chosen from polyvinyl alcohols, starch ethers, cellulose ethers, guar ethers or clays, such as bentonite. This composition can be used in a spraying device operating in continuous or noncontinuous mode and makes it possible to obtain lightweight hardened mortars by virtue of a very good stability of the paste. The present invention also relates to a process for the preparation of a construction material, to the material thus obtained and to the use thereof in the construction field.

Description

STRONGLY LIGHT MORTAR COMPOSITION AND THERMAL INSULATION

The present invention relates to a thermally insulating lightened mortar composition, the low density of the dough after kneading remains stable during the plastic phase of the mortar (that is to say before the hardened phase). This stability of the dough makes it possible to obtain cured products of low density whatever the method of implementation (manual, by casting or by pumping) and whatever the machine used (machine or mortar pump, continuous mixing or discontinuous). The present invention also relates to the use of this composition in the field of construction, in particular for the thermal insulation of floors, ceilings and / or walls and the filling of insulating blocks or interstitial voids, for example wall cavities. .

Today we try to lighten as much as possible insulating mortars, both for facade type solutions and in particular for external thermal insulation systems (ITE or ETICS in English) as for materials for the soil in order to form lightened screeds. Traditionally, the lightening of insulating mortars is obtained by the use of leaching loads such as, for example, mineral fillers such as perlite, vermiculite, expanded clays, or with synthetic organic fillers such as expanded polystyrene beads. However, the simple addition of these lightening loads does not achieve very low densities while maintaining the desired maneuverability for the desired applications. By increasing the amount of leaching loads in the formulations too much, we are confronted with problems related on the one hand to too high concentrations of granular particles (maximum granular stacking achieved) and on the other hand to problems of pumpability or workability of pasta obtained from these formulations. The only way to further improve the relief is to use foamed formulations and thus add specific additives to increase the amount of air occluded, that is to say the amount of air contained in the paste or in the mortar once hardened. Some of these additives can generate in-situ gases and thus form foams generating bubbles. Others are of the air-entraining type and make it possible to entrain air during the preparation phases of the compositions, in particular during mixing with the mixing water. The use of these types of air entrainers remains however limited because it is difficult to obtain the stability of the air entrained either in time, or when passing in the projection tools that strongly urge the dough, in particular by significant shears. It is indeed important that mortars, even of low density, have good workability or workability and that once hardened, they have the expected strength properties. The air entrained during the mixing must remain stable as soon as the bubbles form during mixing and also during the operation of the dough and until the start of the curing phase. It is considered that the entrained air is stable when the difference between the densities of the dough measured at t0, that is to say immediately after kneading and at 30, 30 minutes after kneading, is less than 100 kg. / m ³ (according to CSTB certification). Patent FR 2 955 103 proposes mineral foams obtained by adding a conventional air-entraining agent and a complex foaming adjuvant comprising a modified starch ether, a stabilizer comprising at least one polyacrylamide and a film-forming polymer. The apparent densities of the cured product that are the lowest attainable with these formulations and measured at 28 days are of the order of 370 kg / m ³ , which remains densities considered high to reach thermal conductivities of less than 55 mW / m. K. Today, it is still very difficult to obtain very light mortars, that is to say ones whose apparent density is less than 250 kg / m ³ in the hardened state, and manageable by the use of air-entraining additives. Indeed, the bubbles generated during the mixing of the mortar with the mixing water collapse very quickly. The low densities measured just after mixing are not perennial and tend to increase very rapidly within minutes of mixing. In addition, the bursting of the bubbles created during the mixing causes a degradation of the workability of the product which then loses its creaminess.

Solutions currently known to obtain cured products whose apparent densities in the cured state are less than 250 kg / m ³ use in particular compositions based on polystyrene beads. These charges, because of their organic nature, have in particular poor properties in terms of fire resistance.

The only solutions known to date which allow to obtain mortars or pastes having a density in the cured state is less than 250 kg / m ³ consist in adding, in the pulp or in the mortar, foam previously generated by a generator or to introduce a quantity of air, or gas, in the dough or the still fresh uncured mortar. However, foam generation techniques and their introduction into a cementitious paste or mortar, even if in the factory they can be controlled and controlled, remain very complex and often not compatible with the on-site application instructions, particularly because of preparation too long. Another disadvantage of foams or foams, bubbled, or gasified, remains the stability of the bubbles created or introduced during the pumping and projection phases.

There is currently no formulation of products of very low apparent density (less than 250 kg / m ³ ) which are based on mineral lightening loads, which can be projected with conventional projection machines operating continuously or discontinuous, under usual mixing conditions that is to say with kneading times customary for those skilled in the art (a few seconds for a continuous machine and of the order of 5 minutes for a discontinuous machine), and who have sufficient maneuverability and resistance. It is in this context that the present invention relates to a mortar composition for obtaining products whose paste densities after mixing are very low and remain stable over time, and which have in the state cured satisfactory mechanical strengths. The present invention also relates to a method of preparing building material from said mortar composition. The building material obtainable by mixing such a composition or from this preparation process and its use are also objects of the present invention.

Surprisingly, the inventors have discovered that by combining certain inorganic hydraulic binders with leaching loads a large amount of air could be introduced by addition of a conventional air-entraining agent and thus obtain a very important relief, while keeping a very good stability of the volume density of the dough and very good handling in the fresh state. Thus, the amount of air entrained by the formulation proposed in the present invention is such as to halve the density relative to a formulation that would conventionally use lightening loads, and this with perfect stability and a very advantageous cost.

The composition according to the present invention is a pre-mixed dry composition ready for use in the sense that its constituents are already premixed and where it is sufficient to mix it with the mixing water. It is not necessary to add other stabilizer to the dry composition when preparing the mortar on site.

The mortar obtained from the composition according to the present invention has a thermal conductivity less than or equal to 55 mW / m. K. and a compressive strength at 28 days of at least 0.40 MPa, which makes it possible to classify it in type CS 1 mortars according to standard NF EN 998-1, relating to industrial mortars. It also has improved acoustic properties, especially in terms of sound absorption.

An object of the present invention is a thermally insulating mortar composition which is free of siliceous or calcareous aggregates of a size greater than 100 μιτι, and which comprises a mixture of at least:

40% by weight of mineral lightening fillers whose bulk density is less than 200 kg / m ³ ,

a mineral binder chosen from sulfo-aluminous cements, aluminous cements and / or binary or ternary binders comprising at least one aluminous or sulfoaluminous cement,

a surfactant-type air entrainment agent chosen from organic fatty acids, sulphated compounds, sulphonated compounds and / or natural wood resins, and

a viscosing agent chosen from polyvinyl alcohols, starch ethers, cellulose ethers, guar ethers or clays such as bentonite. Unless otherwise indicated, the percentages of the various constituents of the dry composition are given in percentages by weight and relate to the total composition of the composition.

The bulk density of a granular filler is the mass per unit volume taking into account voids present in or between grains. It is given in kg / m ³ .

The composition according to the present invention does not comprise siliceous aggregates, limestone and / or silico-limestone having a particle size greater than 100 μητι. The absence of coarse aggregates advantageously makes it possible to obtain the desired lightening. Preferably, the composition according to the present invention comprises less than 5% of siliceous fillers, limestone and / or silico-limestone having a particle size less than 100 μητι. Even more preferentially, the composition is free of siliceous, calcareous and / or silico-calcareous fillers having a particle size of less than 100 μητι.

The mortar composition according to the present invention comprises at least 40% by weight of lightening mineral fillers whose bulk density is less than 200 kg / m ³ . These charges are in particular of spherical shape and have an average diameter less than or equal to 80 μητι. The mineral lightening fillers are chosen from expanded perlite, expanded vermiculite, expanded glass beads, hollow glass microspheres, cenospheres, expanded clays, expanded shales, pumice stones, expanded silicates and / or aerogels. . In a preferred manner, the mineral lightening fillers are chosen from expanded perlite, expanded vermiculite, expanded glass beads, hollow glass microspheres, cenospheres, expanded clays, expanded shales, pumice stones and / or silicates. expanded. Even more preferably, the lightening mineral fillers are perlite, which may be hydrophobic. Hydrophobized perlite may be advantageous in formulations intended to improve thermal insulation.

Preferably, the composition according to the present invention comprises at least 50% by weight of lightening mineral fillers and more preferably at least 60% by weight. The composition according to the present invention comprises a hydraulic mineral binder chosen from sulfo-aluminous cements, aluminous cements and / or binary or ternary binders comprising at least one aluminous or sulfoaluminous cement. This type of binder advantageously makes it possible to contribute to the stability of the lightened dough produced. Aluminous cements are based on calcium aluminate. The sulfo-aluminous cements consist of a mixture of sulfo-aluminous clinker and calcium sulphates hydrate (gypsum, semi-hydrate) or not (anhydrite). This name covers many compositions which have in common the presence of calcium sulfoaluminate. Mention may be made, for example, of alitic sulphoaluminous cement, of alumitic cement, of belitic sulpho-aluminous cements. Binary or ternary binder is used when the hydraulic binder consists of a mixture of several binders. The binary or ternary binders within the meaning of the present invention comprise a mixture of at least one aluminous or sulfo-aluminous cement, with respectively one or two other binders such as Portland cements, slags, natural or artificial lime and / or sources of calcium sulphate such as plaster or hemihydrate, gypsum and / or anhydrite. According to the present invention, the binary or ternary binder comprises less than 30% by weight of Portland cement and / or lime with respect to the total weight of binder. Too much Portland cement and / or lime in the binder could cause an increase in pH, which appears to be detrimental to the stability of the entrained air. The amount of binders whose pH is greater than or equal to 12.4 should not be too great in the composition according to the present invention.

The composition according to the present invention advantageously comprises a large amount of air entraining agent. It comprises at least 0.3% by weight of air entraining agent. Thus, with such a quantity, it becomes possible to entrain a lot of air during the mixing with water of the dry composition under usual mixing conditions and thus to significantly reduce the final product. Preferably, said composition comprises at least 0.5% by weight of air-entraining agent. Contrary to what was known, thanks to the particular choices of the constituents of said composition, it becomes possible to entrain more air, while maintaining the stability of the relief obtained. The coaching agent of air is chosen from alkyl sulphates, alkyl sulphonates and alkyl aryl sulphates, alone or as a mixture. These agents are those conventionally used in lightened mortar formulations. Preferably, the air-entraining agent is sodium lauryl sulphate. A significant improvement in lightening therefore becomes possible, by judiciously choosing the various constituents of the composition according to the present invention, and by using an air entrainment agent considered as simple and therefore cheap.

The composition according to the present invention also comprises a viscosing agent which is chosen from polyvinyl alcohols, starch ethers, cellulose ethers, guar ethers or clays. The presence of such an agent in an amount of between 0.01% and 2% by weight contributes to the stability of the entrained air. Preferably, the viscosing agent is a cellulose ether such as ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylmethylcellulose or hydroxypropylmethylcellulose. This agent plays in particular on the rheology of the composition in the fresh state, and in particular on the retention of water. It is a simple viscosifying agent, usually used in mortar formulations. No complex mixture such as those described in the prior art is necessary to obtain a stable paste. The viscosifying agent participates notably in the trapping of the air bubbles created by the air-entraining agent and in their static and dynamic stability over time by increasing the flow threshold as well as the dynamic viscosity of the interstitial fluid between the solid particles and air bubbles. Preferably, the content of viscosity agent in the composition is preferably between 0.1% and 1% by weight.

According to one embodiment, the composition further comprises a polymeric additive which is a copolymer of vinyl type, of acrylic type and / or of carboxylic acid derivative and more preferably a copolymer of vinyl acetate, of vinyl versatate and of methacrylic acid and / or ester, maleic ester, olefin and / or vinyl chloride.

The composition according to the present invention may also further comprise rheological agents such as plasticizers or superplasticizers, water-retaining agents, thickening agents, biocidal and / or fungicidal protection, dispersing agents, pigments, accelerators and / or retarders, water-repellent agents, fibers. The respective amount of these agents depends on their nature. They are generally between 0.01% and 2% by weight. It is possible to introduce, for example, larger amounts of certain additives, and in particular fibers.

The composition according to the present invention, when mixed with mixing water can be manually applied, cast or can be mechanically sprayed onto a support.

Another object of the present invention is a method of preparing by projection of a building material from the mortar composition described hereinbefore. The method according to the present invention comprises the steps of:

mixing said composition with the mixing water in the mixer of a projection device to obtain a paste,

-pumping of the dough thus obtained to the lance of the projection device, then

-projection on the support.

The composition according to the present invention can advantageously be pumped and used in a mortar spraying process. This type of process is generally critical for lightweight mortar compositions. It is indeed common for a mortar composition to have the desired lightening before projection but once introduced into the projection device and projected on the support, it loses its lightening properties. Surprisingly, the composition according to the present invention retains lightening properties, even once it is pumped and transferred to the spraying lance. The paste obtained is projected onto the support, generally by successive passages. The support is thus covered with several centimeters of mortar; the thickness depending on the nature of the support and / or type of finish sought. The method according to the invention optionally comprises a finishing step, consisting of making the surface homogeneous and smooth. For an application as a facade, this finishing step is mandatory: it allows in particular to obtain a flat surface for the application of the finishing coating necessary for increase the surface hardness and ensure the protection, including waterproofing, of the facade.

The mixing step in the blender of the blasting device varies from a few seconds for a continuous blending machine to several minutes in the case of batch blending machine. The mixing time in the mixer of the projection device is between 15 seconds and

10 minutes.

The process according to the present invention can be carried out with a batch mixing mortar machine, in the sense that a defined quantity of dough is spun and then sprayed. These are machines that are conventionally used, such as the Putzmeister SP1 1 projection machines.

It can also be implemented continuously, for example with a Mtec M330 type mortar machine.

An object of the invention relates to a lightweight construction material that can be obtained by the method described above, or after mixing a composition as described above. Said material has a thermal conductivity less than or equal to 55 mW / m. K. and a compressive strength at 28 days of at least 0.40 MPa. The material according to the present invention is a lightened material, very good thermal insulator and sufficiently mechanically resistant for the desired application. The performances obtained in terms of mechanical strength allow it to be classified in the category CS 1 mortars according to standard NF 998-1.

The present invention also relates to the use of the material described above and having a thermal conductivity less than or equal to 55 mW / m. K. and a 28-day compressive strength of at least 0.40 MPa as screed, wall underlayment, ceilings, insulating masonry block filler material or interstitial void fillers and wall cavities. The examples below illustrate the invention without limiting its scope.

Several mortar compositions are prepared by mixing the various constituents in a conventional powder mixer and are given in detail in Table 1 below. During the preparation of the dough, these formulations are mixed with mixing water. The mixing rate is given as a percentage: a mixing rate of 170% indicates that 170 kg of water are added to 100 kg of dry powder. When the formulations are spoiled in the laboratory, the mixing takes place in a Rilem type planetary mixer at a speed of 60 rpm for a period of 90 seconds.

In the examples below, the measurement of the bulk density of the paste is carried out using a cylindrical container with a volume of V of one liter, previously tared and a mass M ₀ . This container is filled with paste twice and tamped by shocks (3 shocks at mid-height and 3 shocks full container), then trimmed and weighed. The measured mass is noted Mi. The density of the pulp in kg / m ³ is equal to the difference between Mi and M ₀ relative to the volume V expressed in m ³ . Compositions C1 to C8 are compositions in accordance with the invention, whereas compositions C9 based on Portland cement and C10 based on aerial lime are given for comparison and are not in accordance with the invention.

C1 C2 C3 C4 C5 C6 C7 C8 C9 C10

Perlite Silcell 42 BC 65 65 65 65 65 65 65 70 65 65 average diameter 45 m

and density

apparent about 130

kg / m ³

Sulphoaluminous cement ALI 28.8

PRE® (Italcementi)

Sulphoaluminous cement ALI 28.8 28.86 28.16 33.8 23.66

CEM® (Italcementi)

Aluminous cement ISTRA 40 28.8 21.36

(Calucem)

Portland Cement 2.8 29.3 CEM I 52.5 (Calcia)

Aerial lime (Boran) 29.3

Molda Plaster 3 Normal 4

(Placo)

Resin copolymer type 5 5 5 5 5 5 5 5 5 5 vinyl acetate,

vinyl versatate and

Maleic ester (Hexion)

Methylhydroxyethylcellulose 0.6 0.6 0.6 0.6 0.5 0.7 0.6 0.6 0.6 0.6 of grade 100 000 mPa.s

(Shinetsu)

Sodium lauryl sulphate 0.6 0.6 0.6 0.6 0.5 1 0.6 0.6 0.6 0.6 (Unger)

Agent accelerator of 0.14 0.14 0.14 0.14

taken: lithium carbonate

Agent accelerator of 0.4

taken: Na ₂ C03

Tackle retardant agent: 0.1

Citric acid

total 100 100 100 100 100 100 100 100 100 100

Table 1

5 Example 1

The composition C9 is kneaded with water with a mixing rate of 170% in a kneader described above for a period of 90 seconds.

The apparent density of the mortar obtained measured at time t = 0 (ie t0) is 420 kg / m ³ . The same measurement carried out after a time of 30 min (ie t30) is worth 600 kg / m ³ , demonstrating a very clear instability of the air entrained in this mortar formulation since the difference between the densities measured at t0 and at t30 is well above 100 kg / m ³ .

In the same manner as above, the composition C10 based on aerial lime is mixed with water at an identical mixing rate (170%). The apparent density values measured respectively at t0 and t30 are 450 kg / m ³ and 750 kg / m ³ , again demonstrating a very high instability of the entrained air.

For the sake of comparison, the same test was carried out with a mortar composition according to the invention identical to compositions C9 and C10, except that the Portland cement or lime was replaced by ALI PRE® sulfo-aluminous cement. The apparent density measured at t = 0 is 405 kg / m ³ and is 450 kg / m ³ after a time of 30 min. With this particular type of binder, the entrained air has good stability.

Example 2

Composition C1 is compared with an identical composition without air-entraining agent, comprising 29.4% by weight of ALI PRE® sulfo-aluminous cement. The bulk density of this slurry without air-entraining is close to 700 kg / ^m3 with a satisfactory stability at 30 min. The addition of 0.6% of air entrainer (composition C1) makes it possible to reduce the apparent density of the pulp up to 350 kg / m ³ . Example 3

Pasta is prepared with compositions C1 to C7 by kneading for 90 seconds before being placed in molds. The mixing rates used are shown in Table 2 below which also summarizes the apparent density values measured at t = 0 (on the fresh dough) and on the cured mortar after 28 days.

Table 2

The above data show that the compositions according to the present invention make it possible to obtain lightened mortars whose density remains low after hardening, attesting to good stability of the dough over time.

The compressive strengths at 28 days of the C2, C5 and C6 mortars were measured and are respectively 0.46 MPa, 0.67 MPa and 0.61 MPa.

Example 4

A composition close to the composition C2 thus based on ALICEM® sulfoaluminous cement is prepared by mixing:

-43% by weight of Silcell 42/18 perlite (hydrophobic perlite with an average diameter of approximately 45 μητι and an apparent density of approximately 130 kg / m ³ )

-22% by weight of Silcell 42 BC perlite (non-hydrophobized perlite with an average diameter of approximately 45 μm and a bulk density of approximately 130 kg / m ³ )

-28.66% by weight of ALICEM® sulfoaluminous cement

-5% by weight of resin type copolymer of vinyl acetate, vinyl versatate and maleic ester (Hexion)

-0.6% by weight of methylhydroxyethylcellulose grade 100 000 mPa.s (Shinetsu)

-0.6% by weight of sodium lauryl sulphate -0.14% by weight of lithium carbonate

This composition is spoiled (mixing rate of 160%) in the kneader described above. The mixing time is varied so as to vary the amount of entrained air. Apparent density measurements of the paste at 100, as well as the hardened mortar at 28 days are shown in Table 3 below. The compressive strength at 28 days is also indicated in MPa.

Table 3

Thus it is found that the longer the mixing is extended, the more the amount of entrained air is increased, while maintaining a good stability of the air entrained over time, even for longer mixing times.

Example 5

The composition of Example 4 is spoiled (mixing rate of 155%) and kneaded for 5 min before being projected onto a wall of breeze blocks with a Putzmeister SP1 type 1 machine. This mixing gives a paste whose bulk density is 350 kg / m ³ in the tank, 356 kg / m ³ at the projection lance outlet and 170 kg / m ³ after curing after 28 days. The compressive strength measured on a sample of 4 * 4 * 4 cm after 28 days is 0.52 MPa and the thermal conductivity is 52 mW / m. K.

Example 6

The composition C8 is spoiled (mixing rate of 147%) and kneaded for 5 min before being projected onto a wall of blocks with a Putzmeister SP1 type machine 1. This mixing gives a paste whose bulk density is 380 kg / m ³ tank, 320 kg / m ³ by spraying lance outlet and 155 kg / m ³ after curing at 28 days. The compressive strength measured on a sample of 4 * 4 * 4 cm after 28 days is 0.42 MPa and the thermal conductivity is 49 mW / m. K. Example 7

The composition of Example 4 is projected with a continuous mixing machine of the Mtec M330 type. The water flow is 250 l / h. The bulk density of the slurry measured at the outlet of lance is 380 kg / m ^3, which is quite comparable with the values obtained with batch mixing machines.

Claims

Thermally insulating mortar composition characterized in that it is free of siliceous, calcareous and / or silico-calcareous granules with a particle size greater than 100 m and comprises a mixture of at least:

- 40% of mineral lightening loads whose apparent density is less than 200 kg / m ³ ,

a surfactant-type air-entraining agent chosen from organic fatty acids, sulphated compounds, sulphonated compounds and / or natural resins of wood and

a viscosing agent chosen from polyvinyl alcohols, starch ethers, cellulose ethers, guar ethers or clays. Composition according to the preceding claim characterized in that it comprises less than 5% by weight of siliceous fillers, limestone and / or silico-limestone particle size less than 100 μιτι, or more preferably is free of siliceous fillers, limestone and / or silico -calcium of particle size less than 100 m.

Composition according to one of the preceding claims, characterized in that the mineral lightening fillers are spherical and have an average diameter less than or equal to 80 m.

Composition according to one of the preceding claims, characterized in that the lightening fillers are chosen from perlite, vermiculite, expanded glass beads, hollow glass microspheres, cenospheres, expanded silicates, and / or aerogels.

Composition according to one of the preceding claims characterized in that it comprises at least 50% by weight of mineral lightening fillers, preferably at least 60% by weight.

6. Composition according to one of the preceding claims characterized in that the binary or ternary binder comprises less than 30% by weight of Portland cement and / or lime based on the total weight of binder.

7. Composition according to one of the preceding claims characterized in that it comprises at least 0.3% by weight of air entraining agent.

8. Composition according to one of the preceding claims, characterized in that the air-entraining agent is chosen from alkyl sulphates, alkyl sulphonates, alkyl aryl sulphates, alone or as a mixture.

9. Composition according to the preceding claim characterized in that the air-entraining agent is sodium lauryl sulphate.

10. Composition according to one of the preceding claims characterized in that it further comprises a polymeric additive which is a copolymer of vinyl type, acrylic type and / or carboxylic acid derivative and more preferably a copolymer of acetate of vinyl, vinyl versatate and methacrylic acid and / or ester, maleic ester, olefin and / or vinyl chloride.

1 1. Composition according to one of the preceding claims characterized in that the amount of viscosity agent is between 0.01% and 2% by weight.

12. Composition according to one of the preceding claims characterized in that it further comprises rheological agents such as plasticizers or superplasticizers, water-retaining agents, thickening agents, biocidal and / or fungicidal protective agents. , dispersing agents, pigments, accelerators and / or set retarders, water-repellent agents, fibers, preferably in an amount of between 0.01% and 2% by weight.

13. Process for preparing a building material from the mortar composition according to one of claims 1 to 12, characterized in that it comprises the steps of:

-pumping of the dough thus obtained to the lance of the projection device, then -projection on the support.

14. Method according to the preceding claim characterized in that the mixing time in the mixer of the projection device is between 15 seconds and 10 minutes.

15. Lightened construction material obtainable by the method according to one of claims 13 or 14 or by mixing with water of the composition according to one of claims 1 to 12 and having a lower thermal conductivity or equal to 55 mW / m. K. and a compressive strength at 28 days of at least 0.40 MPa.

16. Use of the material according to the preceding claim as a screed, under-wall, ceiling, insulating masonry block filling material, interstitial voids filling material or wall cavities.