Improved earth-based mortar

Abstract

The present invention relates to a method for spraying or injecting an earth-based mortar comprising the steps of: i) preparing the mortar by mixing: ia) earth from earthworks or excavation operations (quarry), or crushed deconstruction materials (concrete, brick, plaster, stone, and mortar), excluding topsoil, with a particle size less than or equal to 20 mm in a volume proportion of 20 to 55%; ib) a binder comprising slag or metakaolin and, optionally, lime, in a volume proportion of 15 to 50%; ic) a material having a silica content greater than 50% (by weight), an open porosity greater than 45%, a particle size less than or equal to 5 mm, and in a volume proportion of 2 to 25%, id) aggregates with a particle size between 2 and 20 mm, and in a volume proportion of 0 to 20%; id) fibers in a volume proportion of between 0 and 30%;ie) the crystallizer in a volume proportion of between 0 and 15%; andif) water in a volume proportion of between 5 and 25% ii) pumping the mixture obtained in i); andiii) injecting the mixture into a mold or projecting the mixture onto a vertical or horizontal surface.;

Description

Title of the invention: Improved earth-based mortar

[0001] The present invention relates to a method of manufacturing an earth-based mortar, which mortar can be used by injection or by projection.

[0002] Although concrete is still the benchmark construction material today, new environmental regulations (RE 2020) require that, in order to calculate the environmental performance of a building, account be taken not only of the insulation of this construction but also of the overall environmental impacts associated with this construction.

[0003] Faced with this problem, the inventors developed a mortar using the earth from the construction site, which mortar is described in French patent applications FR 20 / 02525 and FR 21 / 02501. Now, and to benefit from optimal performance, this mortar had to integrate a crystallizer and a significant proportion of lime, which was generally greater than 15% by volume, or even 20%.

[0004] The inventors have now developed a new earth-based mortar whose performance is improved while using lower proportions of lime, but also of crystallizer. The addition of a porous silica-based material makes it possible to achieve the desired performance of the final product, even when the mortar does not include a crystallizer.

[0005] To do this, the mortar according to the invention incorporates a porous material rich in silica (such as, for example, diatomaceous earth, glass wool waste (e.g., cullet and fibers), refractory brick waste (e.g., dust and residues), etc.).

[0006] Consequently, a first object of the invention therefore relates to a method of spraying or injecting an earth-based mortar comprising the steps of:

[0007] i) preparation of the mortar by mixing:

[0008] ia) an earth with a particle size less than or equal to 20 mm, preferably less than or equal to 15 mm in a volume proportion of 20 to 55% and, particularly preferably, of 20 to 40%;

[0009] ib) a binder comprising slag or metakaolin and, optionally, lime, in a volume proportion of 15 to 50%, preferably 25 to 45%;

[0010] ic) a material having a silica content greater than 50% (by weight), an open porosity greater than 45%, a particle size less than or equal to 5 mm, preferably 2 mm, and in a volume proportion of 2 to 25%, preferably 3 to 20% and, particularly preferably, 4 to 18%, for example 4 to 10%;

[0011] ic) aggregates with a particle size of between 2 and 20 mm, preferably between 2 and 15 mm, and in a volume proportion of 0 to 20%;

[0012] id) fibers in a volume proportion of between 0 and 30%, preferably between 10 and 30% and, particularly preferably, between 10 and 20%;

[0013] ie) of the crystallizer in a volume proportion of between 0 and 15%; preferably between 0.1 and 10% and, particularly preferably, between 0.2 and 5%; and

[0014] if) water in a volume proportion of between 5 and 25%, preferably between 5 and 20%;

[0015] ii) pumping the mixture obtained in i); and

[0016] iii) injecting the mixture into a mold or projecting the mixture onto a vertical or horizontal surface.

[0017] The volume proportion of each component corresponds to the volume occupied by this component in relation to the total volume of the mortar mixture.

[0018] Advantageously, the porous and silica-rich material is chosen from the group comprising diatomaceous earth, glass or rock wool waste (e.g. cullet and fibers), refractory brick waste (e.g. dust and residues).

[0019] Preferably, the silica-rich porous material used in the mortar according to the invention is diatomaceous earth. This is also known as kieselguhr. It is a siliceous sediment with a very high porosity, giving it significant liquid absorption properties. The presence of such a porous material in the mortar advantageously makes it possible to adjust the proportion of water and improves the performance of the material obtained.

[0020] Glass wool or refractory brick waste, when crushed, is also a porous material rich in silica which in particular helps to strengthen the binding function of the mortar.

[0021] Advantageously, the particle size of this material is less than 1 mm. Typically, this particle size is between 1 and 500 μm.

[0022] Preferably, the porous, silica-rich material has a silica content greater than 80% (by weight) and, particularly preferably, greater than 90%.

[0023] A porous material is a material containing small pores or cavities and capable of containing one or more fluids (liquid or gas). A structure is said to have open porosity when the pores are connected to each other, thus forming very fine channels. Such an open porosity structure makes water absorption possible.

[0024] The silica-rich material is a material whose so-called "open" porosity is greater than 45%. Porosity is a physical quantity between 0 and 100% (or between 0 and 1), which conditions the flow and retention capacities of a substrate. This open porosity is measured conventionally by mercury intrusion porosimetry, that is to say by a method consisting of causing mercury to penetrate into the pores of a sample under increasing pressure.

[0025] More preferably, the porous and silica-rich material has an open porosity greater than 60% and, particularly preferably, greater than 80%, or even greater than 90%.

[0026] Mortar means both a coating, which can be applied to a surface and has a strength of at least 5 MPa, a mounting or filling mortar with a strength of at least 10 MPa, and a mortar intended for the manufacture of a load-bearing wall with a strength of at least 15 MPa.

[0027] The method according to the invention can therefore allow the creation of both a coating and a wall.

[0028] Advantageously, the mortar prepared by the process according to the invention comprises cement in a volume proportion of less than or equal to 5%, preferably less than or equal to 0.5% and, particularly preferably, a volume proportion of 0% of cement.

[0029] The environmental impact of the process according to the invention is therefore much less than that of existing processes which generally use at least 10% cement.

[0030] By earth is meant earth resulting from earthworks or excavation operations (quarry), or crushed deconstruction materials (excluding topsoil).

[0031] By deconstruction material we mean concrete, plaster, stone or even mortar.

[0032] Advantageously, the earth is chosen from the group comprising earth resulting from earthworks or excavation operations (quarry).

[0033] This earth may therefore present a very great diversity of nature depending on the site from which it comes. It will thus be possible to find earths incorporating gypsum, silt, limestone, silica, clay or even their mixture. Preferably, said earth will incorporate a clay content less than or equal to 50% by weight, preferably less than or equal to 25% and, particularly preferably, less than or equal to 10%. Such a content can be determined by a granulometric method such as that described in standard NF X31-107.

[0034] Now, the earth does not come from sand quarries, nor from aggregate quarries (virgin aggregates).

[0035] Furthermore, it will be preferred to have an earth which has undergone at most one pretreatment by grinding, sorting (e.g. according to the color), sieving and / or drying before being mixed with the other components of the earth mortar. Now, the earth used in the mortar according to the invention has not undergone any sorting or sieving step so as to eliminate the elements having a dimension between 10 and 20 mm, preferably between 10 and 15 mm. It should be noted that the earth used has therefore not undergone any chemical pretreatment, such as pretreatment with a surfactant, which pretreatment with a surfactant, in connection with a clay, allows its structure to be modified in order to allow its liquefaction.

[0036] Prior to using earth, care should be taken to determine the presence or absence of traces of metallic elements (Pb, As, etc.) so as to prevent any contamination.

[0037] Advantageously, the earth used in the method according to the invention will have a particle size less than or equal to 10 mm, preferably less than or equal to 6 mm.

[0038] Obtaining soil of a desired particle size from such a variety of sources will generally require, in addition to determining the particle size of the soil, a sieving operation.

[0039] According to a preferred embodiment, the method according to the invention will therefore preferably comprise a step of sieving the earth prior to step i).

[0040] The very high adaptability of the method according to the invention to the different types of existing earth allows it to use the earth itself from the site on which the method is implemented.

[0041] According to another preferred embodiment, the method according to the invention will preferably comprise a step prior to step i) of extracting the earth and, optionally, sieving it.

[0042] Slag is understood to mean the slag formed during the melting or production of metal by liquid means. It is a mixture composed essentially of silicates, aluminates and lime with various metal oxides with the exception of iron oxides.

[0043] The slag will preferably be used in a volume proportion of between 10 and 40%, preferably between 10 and 30%.

[0044] By metakaolin is meant the product of a calcination of kaolin and / or kaolinic clay.

[0045] Preferably, the binder comprises slag and, optionally, lime.

[0046] The lime will preferably be used in a volume proportion of between 0 and 20%, preferably between 1 and 20%, for example between 1 and 15%, and particularly preferably between 1 and 10%.

[0047] Lime is understood to mean artificial lime which essentially comprises calcium and magnesium oxide and / or calcium and magnesium hydroxide.

[0048] Advantageously, the lime is chosen from the group comprising hydraulic lime and air lime.

[0049] Preferably, hydraulic lime will be used, which preferably does not include cement.

[0050] Preferably, a hydraulic lime NHL 3.5 or NHL 5 will be used.

[0051] Preferably, the use of NHL 3.5 Z or NHL 5 Z hydraulic lime will be avoided, since it contains cement.

[0052] Aggregates include both natural aggregates (e.g. gravel or sand) and recycled aggregates (e.g. crushed concrete or mortar).

[0053] Now it is possible to mix different types of aggregates, natural and recycled, in varying proportions.

[0054] As regards the particle size, a particle size of between 4 and 10 mm will be preferred and, in a particularly preferred manner, a particle size of between 4 and 6 mm.

[0055] As with earth, it is possible to use aggregates from all or part of the site on which the process is implemented.

[0056] In the case where the earth used includes aggregates. Then the proportion of aggregates added in addition to the earth is adapted so that the total volume proportion of aggregates is between 0 and 20%, preferably between 5 and 20% and particularly preferably between 10 and 20%.

[0057] According to yet another preferred embodiment, the method according to the invention will preferably comprise a step prior to step i) of extracting aggregates and, optionally, sieving them.

[0058] By crystallizer, sometimes also called mineralizer, we mean compounds capable of forming, by a reaction called mineralization and with the soluble compounds of the mortar (free lime), crystalline and insoluble complexes.

[0059] Examples of such compounds that may be mentioned include, for example, silicate salts, carbonate salts (e.g. sodium carbonate (e.g. natron), alginate salts.

[0060]

[0061] Such crystallizers are known for use in waterproofing concrete, in particular under the names PENETRON, XYPEX, VANDEX, mineralizing B HYDRO-MINERAL, etc.

[0062] Preferably, the crystallizer comprises silicate ions capable of forming silicate complexes with calcium hydroxide, in particular calcium, magnesium, sodium or potassium silicate.

[0063] According to a preferred embodiment of the method according to the invention, step ie) is carried out simultaneously or consecutively to step ib), preferably simultaneously.

[0064] By fibers is meant both synthetic fibers (e.g. polypropylene fibers, glass fibers, carbon fibers, etc.) and natural fibers (e.g. hemp), which fibers can be in any form (elongated or circular), preferably in an elongated form.

[0065] Advantageously, the fibers used are solid fibers, that is to say they have a structure devoid of cavities.

[0066] Typically, the fibers used have a length of between 5 and 100 mm, preferably between 5 and 70 mm and, particularly preferably, between 10 and 50 mm.

[0067] According to a preferred embodiment, natural fibers or plant fibers will be used. To obtain such plant fibers, fiber plants, a large part of which are well known, may be used.

[0068] For bast fibers, corresponding to bark fiber, we can cite as examples hemp, jute, kenaf, barrel vine, linen, nettle, papyrus, esparto, linden fibers, bamboo fibers, Provence cane fibers, sea rush, miscanthus fibers, bagasse, etc.

[0069] For leaf fibers, we can cite Manila hemp (from abaca), pina (from pineapple), agave leaf fiber (e.g. sisal).

[0070] For fibers from seeds or fruit, we can cite coir, rice husk or straw or even cotton.

[0071] Finally, the mortar may incorporate other additives such as plasticizing agents, water-retaining agents, water-repellent agents, biocides, fungicides, dispersants, air entrainers (chasers), setting accelerators, setting retarders, fluidifiers, antifreeze agents or even expansion agents.

[0072] Naturally, each of these adjuvants can be added to the mortar alone or in combination with one or more other adjuvants.

[0073] Step i) of mixing can be carried out according to techniques well known to those skilled in the art.

[0074] Advantageously, the mixing is carried out using a mixer, in particular a mobile mixer with horizontal or vertical axes allowing the mixing to be carried out on the very site where the wall is to be built.

[0075] If the earth-based mortar cannot be used immediately after step i), it is also possible, by omitting to add at least the water, to bag the mixture during step i) for its transport and / or storage before being finalized prior to its use in step ii) of the process according to the invention.

[0076] Step ii) of pumping can be carried out according to techniques well known to those skilled in the art.

[0077] This pumping step is carried out using a pumping means such as a piston pump or a worm pump.

[0078] Advantageously, the mixture is heated to a temperature greater than or equal to 40°C, preferably greater than or equal to 45°C during this pumping step so as to allow rapid setting of the mortar, especially in the case of projection onto a vertical surface.

[0079] Such a temperature may possibly be obtained by the sole friction of the mixture obtained at the end of step i) with the surfaces of the device allowing pumping (e.g. friction of the mixture with the surface of the worm screw).

[0080] According to a particular embodiment of the method according to the invention, the latter is intended for injection into a mold for a construction element.

[0081] Indeed, the specificities of the mortar obtained allow its industrial use in the manufacture of construction elements such as borders, concrete blocks, paving stones, etc.

[0082] By mold of at least one construction element, we mean a mold chosen from the group comprising molds for concrete blocks, hollow or solid, borders, paving stones and slabs.

[0083] In this case, the method according to the invention may further comprise the step of:

[0084] iv) compression of the injected mixture into a mold for at least one construction element.

[0085] This compression step is carried out by devices well known to those skilled in the art.

[0086] If necessary, this step can be followed or preceded by a step of stirring the mixture in the mold to limit the presence of bubbles.

[0087] Also, the method according to the invention may further comprise the step of:

[0088] v) stirring the mixture in the mold.

[0089] This stirring step can be carried out by means of vibrating devices positioned in the mold or associated with it. Examples include vibrating tables or vibrating probes (needles).

[0090] This step may be followed by a step vi) of drying and demolding.

[0091] According to another particular embodiment of the method according to the invention, the latter is intended for projection onto a horizontal or vertical surface, preferably onto a vertical surface.

[0092] Indeed, and surprisingly, the characteristics of the earth-based mortar according to the invention, and in particular its rapid setting, allow it to be projected onto a vertical surface in layers of around ten centimetres and without observing any sagging. It is also possible to carry out successive applications of the mortar according to the invention by applying a covering time of between 30 minutes and 6 hours between two successive layers, preferably between 1 and 3 hours.

[0093] Advantageously, the method according to the invention allows the production of a thickness of earth-based mortar of up to 50 cm, preferably up to 25 cm. It should be noted that this thickness can be produced by means of one or more applications of the mortar on the surface. Typically, each application will increase the thickness by at most 10 cm.

[0094] Now and preferably, the surface onto which the earth-based mortar is projected comprises a reinforcing element, which can for example take the form of a reinforcement, which reinforcement can be metallic, plastic (polyethylene, polypropylene, etc.) or plant-based (bamboo, Provence cane, etc.).

[0095] As for the projection as such, it is carried out by means of devices well known to those skilled in the art. Typically, such projection is carried out by means of a projection lance placed at the outlet of the pumping means.

[0096] Such a projection lance takes the form of a flexible pipe of suitable cross-section at the end of which is positioned a projection nozzle. Typically, such a projection lance further incorporates an air inlet slightly upstream of the nozzle, which air inlet contributes to the projection of the earth-based mortar and to the entrainment of said earth-based mortar with a view to its projection onto a vertical or horizontal surface.

[0097] A second object of the invention relates to the earth-based mortar as obtained at the end of step i) of the method described above.

[0098] Such a mortar according to comprises:

[0099] a) an earth with a particle size less than or equal to 20 mm, preferably less than or equal to 15 mm in a volume proportion of 20 to 55%, preferably 20 to 40%;

[0100] b) a binder comprising slag or metakaolin and, optionally, lime, in a volume proportion of 15 to 50%, preferably 25 to 45%;

[0101] c) a material having a silica content greater than 50% (by weight), an open porosity greater than 45%, a particle size less than or equal to 5 mm, preferably 2 mm, and in a volume proportion of 2 to 25%, preferably 3 to 15% and, particularly preferably, 4 to 12%;

[0102] d) aggregates with a particle size of between 2 and 20 mm, preferably between 2 and 15 mm, and in a volume proportion of 0 to 20%;

[0103] e) fibers in a volume proportion of between 0 and 30%, preferably between 10 and 30%, and particularly preferably between 10 and 20%;

[0104] f) of the crystallizer in a volume proportion of between 0 and 15%; preferably between 0.1 and 10% and, particularly preferably, between 0.2 and 5%; and

[0105] g) optionally water in a volume proportion of between 5 and 25%, preferably between 5 and 20%.

[0106] The characteristics and proportions of each component of the mortar are as described above.

[0107] Advantageously, the mortar according to the invention is packaged in a bag and does not contain water.

[0108] A third subject of the invention relates to a mixture intended for the preparation of a mortar according to the invention, which mixture comprises:

[0109] a) between 50 and 99% by weight of a binder (relative to the total weight of the mixture) comprising slag or metakaolin and, optionally, lime,

[0110] b) between 1 and 20% by weight of a material having a silica content greater than 50% (by weight), an open porosity greater than 45%, a particle size less than or equal to 5 mm, preferably 2 mm (relative to the total weight of the mixture), preferably between 2 and 15% and, particularly preferably, between 2 and 12%.

[0111] c) between 0 and 30% by weight of crystallizer (relative to the total weight of the mixture), preferably between 0.2 and 15% and, particularly preferably, between 0.5 and 8%.

[0112] Preferably, this mixture does not include earth, aggregates or plant fibers which are intended to be added on site to make the earth-based mortar.

[0113] Advantageously, the binder comprises slag and, preferably, lime.

[0114] Accordingly, a preferred mixture comprises:

[0115] a) between 50 and 85% by weight of slag (relative to the total weight of the mixture), preferably between 55 and 85% and, particularly preferably, between 65 and 80%,

[0116] b) between 3 and 30% by weight of lime (relative to the total weight of the mixture), preferably between 5 and 20% and, particularly preferably, between 5 and 15%.

[0117] c) between 1 and 20% by weight of a material having a silica content greater than 50% (by weight), an open porosity greater than 45%, a particle size less than or equal to 5 mm, preferably 2 mm (relative to the total weight of the mixture), preferably between 2 and 15% and, particularly preferably, between 2 and 10%.

[0118] d) between 0 and 30% by weight of crystallizer (relative to the total weight of the mixture), preferably between 0.2 and 15% and, particularly preferably, between 0.5 and 8%.

[0119] Advantageously, the mixture according to the invention is packaged in a bag and does not include water.

[0120] A fourth object of the invention relates to a construction element capable of being obtained using a mortar as defined previously.

[0121] Such a product can take the form of any construction element, whether concrete block (solid or hollow), curbs, paving stones and slabs.

[0122] A fifth object of the invention relates to the use of a mortar or a mixture as described above for the production of earth-based construction elements.

[0123] By construction elements we mean partitions, blocks, concrete blocks (hollow or solid), borders, paving stones, slabs, etc.

[0124] By production, we mean production by injection or projection.

[0125] Other characteristics, details and advantages of the invention will emerge more clearly from the detailed description given below for information purposes.

[0126] Process for preparing earth mortar

[0127] The site soil was previously sieved with 10 mm mesh.

[0128] The sieved site soil is then incorporated into the mixer tank of a TURBOSOL T20X spraying machine. 4 / 6 gravel and hemp fibers (10 mm) are then added and the mixture is rapidly mixed for a few minutes (usually about 2 minutes). Water is then added to the mixture and the rapid mixing allows the mixture to be homogenized. Finally, the binder and the silica-rich porous material, as well as the crystallizer when present, are incorporated into the mixture and a longer mixing step is carried out (typically between 3 and 5 minutes) to obtain a smooth consistency of the mortar.

[0129] The mixture is then ready to be sprayed (or injected in the case of preparation of construction elements)

[0130] Examples of formulations

[0131] Different formulations of earth mortar were prepared and made it possible to arrive at the formula according to the invention. The earths tested included gypsum, quarry waste (limestone), silts and clays.

[0132] Some tested formulas are described in Tables 1 to 3.

[0133] [Tables 1] VOLUME MATERIAL (liters) DENSITY WEIGHT (kg) % VOLUME (approx.) % MASS (approx.) LIME 5 0.791 3.96 4% 3% DIATOMACEOUS EARTH 10 0.5 5 8% 4% SLAG 30 1.165 34.95 24% 27% EARTH 30 1.545 46.35 24% 35% GRAVEL 4 / 6 RECYCLED 15 1.26 18.90 12% 14% NATURAL FIBER 15 0.156 2.34 12% 2% CRYSTALLIZER R 2 1.114 2.23 2% 2% WATER 18 1 18 14% 14%

[0134] [Tables2] VOLUME MATERIAL (liters) DENSITY WEIGHT (kg) % VOLUME (approx.) % MASS (approx.) LIME 7.5 0.791 5.93 6% 5% DIATOMACEOUS EARTH 7.5 0.5 3.75 6% 3% SLAG 28 1.165 32.62 23% 25% SOIL 30 1.545 46.35 24% 35% GRAVEL 4 / 6 RECYCLED 15 1.26 18.90 12% 14% NATURAL FIBER 15 0.156 2.34 12% 2% CRYSTALLIZER R 2 1.114 2.23 2% 2% WATER 18 1 18 15% 14%

[0135] [Tables3] VOLUME MATERIAL (liters) DENSITY WEIGHT (kg) % VOLUME (approx.) % MASS (approx.) LIME 5 0.791 3.96 4% 3% DIATOMACEOUS EARTH 11 0.5 5.5 9% 4% SLAG 31 1.165 36.11 25% 28% SOIL 30 1.545 46.35 24% 35% GRAVEL 4 / 6 RECYCLED 15 1.26 18.90 12% 14% NATURAL FIBER 15 0.156 2.34 12% 2% WATER 18 1 18 14% 14%

[0136] Earth mortar projection step

[0137] The projection of the earth mortar is then carried out on a previously prepared support.

[0138] In the tests carried out, wooden frames were produced, which frames had a base made of OSB plywood panel screwed to the wooden structure and a welded mesh type metal grid positioned mid-frame to allow the incorporation of elements traditionally used in the building trades (electrical wiring, water supply, etc.).

[0139] The projection of the different earth mortars described above was then carried out in two successive layers of 7 to 8 cm. The covering time between the two layers was 30 minutes.

[0140] This time can be considered short because in reality the panels produced on a conventional construction site are larger. This will systematically give a longer recovery time (around 1 to 2 hours).

[0141] In the end, the filling panels produced in the workshop represented a final thickness of 15 cm. After projection, the mortar held very well and a finish was carried out (rule, float or trowel depending on the panels). Note that the mortar, not using a crystallizer, showed good strength after projection.

[0142] Additional tests in which diatomaceous earth was substituted by refractory brick waste showed comparable properties.

Claims

Claims

1. A method of spraying or injecting an earth-based mortar comprising the steps of: i) preparing the mortar by mixing: ia) earth from earthworks or excavation operations (quarry), or crushed deconstruction materials (concrete, brick, plaster, stone, and mortar), but not from sand quarries, nor from aggregate quarries (virgin aggregates) and excluding topsoil, with a particle size less than or equal to 20 mm in a volume proportion of 20 to 55%; ib) a binder comprising slag or metakaolin and, optionally, lime, in a volume proportion of 15 to 50%;ic) a material having a silica content greater than 50% (by weight), an open porosity greater than 45% as measured by mercury intrusion porosimetry, a particle size less than or equal to 5 mm, and in a volume proportion of 2 to 25%, id) aggregates having a particle size between 2 and 20 mm, and in a volume proportion of 0 to 20%; id) fibers in a volume proportion of between 0 and 30%; ie) the crystallizer in a volume proportion of between 0 and 15%; and if) water in a volume proportion of between 5 and 25%; ii) pumping the mixture obtained in i); and iii) injecting the mixture into a mold or projecting the mixture onto a vertical or horizontal surface.;

2. The method according to claim 1, characterized in that the material having a silica content greater than 50% (by weight), an open porosity greater than 45% and a particle size less than or equal to 5mm is chosen from the group comprising diatomaceous earth, glass wool waste (e.g. cullet and fibers), refractory brick waste (e.g. dust and residues).

3. The method according to any one of claims 1 or 2, characterized in that the binder comprises slag and, optionally, lime.

4. The method according to any one of claims 1 to 3, characterized in that the crystallizer is chosen from the group comprising silicate salts, carbonate salts and alginate salts.

5. The method according to any one of claims 1 to 4, characterized in that the fibers are synthetic fibers and / or natural fibers.

6. A mortar as defined in any one of claims 1 to 5, characterized in that it comprises: a) an earth with a particle size less than or equal to 20 mm in a volume proportion of 20 to 55%; b) a binder comprising slag or metakaolin and, optionally, lime, in a volume proportion of 15 to 50%; c) a material having a silica content greater than 50% (by weight), an open porosity greater than 45% as measured by mercury intrusion porosimetry, a particle size less than or equal to 5 mm, preferably 2 mm, and in a volume proportion of 2 to 25%, d) aggregates with a particle size between 2 and 20 mm, and in a volume proportion of 0 to 20%; e) fibers in a volume proportion of between 0 and 30%; f) crystallizer in a volume proportion of between 0 and 15%; and g) optionally water in a volume proportion of between 5 and 25%.

7. A mixture intended for the preparation of a mortar as defined in claim 6, which mixture comprises: a) between 50 and 99% by weight of a binder (relative to the total weight of the mixture) comprising slag or metakaolin and, optionally, lime; b) between 1 and 20% by weight of a material having a silica content greater than 50% (by weight), an open porosity greater than 45% as measured by mercury intrusion porosimetry, a particle size less than or equal to 5 mm, preferably 2 mm (relative to the total weight of the mixture); c) between 0 and 30% by weight of crystallizer (relative to the total weight of the mixture).

8. The mixture intended for the preparation of a mortar as defined in claim 7, which material having a silica content greater than 50% (by weight), an open porosity greater than 45% as measured by mercury intrusion porosimetry, a particle size less than or equal to 5mm is diatomaceous earth.

9. The mixture according to claim 7, comprising: a) between 50 and 85% by weight of slag (relative to the total weight of the mixture); b) between 3 and 30% by weight of lime (relative to the total weight of the mixture); c) between 1 and 20% by weight of a material having a silica content greater than 50% (by weight), an open porosity greater than 45% as measured by mercury intrusion porosimetry, a particle size less than or equal to 5 mm, preferably 2 mm (relative to the total weight of the mixture); and d) between 0 and 30% by weight of crystallizer (relative to the total weight of the mixture).

10. A construction element obtainable with a mortar as defined in claim 6.

11. A use of a mortar as defined in claim 6 or of a mixture of one as defined in any one of claims 7 to 9 for the production of earth-based construction elements.