EP4118053A1 - Soil-based mortar - Google Patents

Abstract

The present invention pertains to a method for spraying or injecting a soil-based mortar, comprising the steps of: i) preparing the mortar by mixing: ia) a soil having a particle size of not more than 20 mm in a proportion by volume of 20 to 55%; ib) a binder comprising slag or metakaolin, and optionally lime, in a proportion by volume of 15 to 55%; ic) aggregates with a particle size of between 2 and 20 mm, in a proportion by volume of 0 to 20%; id) fibres in a proportion by volume of between 0 and 30%; ie) crystallizer in a proportion by volume of between 1 and 15%; and if) water in a proportion by volume of between 5 and 20%; ii) pumping the mixture obtained in i); and iii) injecting the mixture into a mould or spraying the mixture onto a vertical or horizontal surface.

Description

EARTH BASED MORTAR

The present patent application claims the priority of the patent application

French FR 2002525 filed on March 13, 2021 and which is hereby incorporated by reference. The present invention relates to a method of manufacturing an earth-based mortar which can be used both by injection and by spraying.

[0003] If you talk about land, it immediately comes to mind that it is one of the oldest building materials. Indeed, building in raw earth made it possible to exploit the closest material, the one you have under your feet, available almost everywhere in the world.

[0004] Now, the mechanical characteristics of it were unsuitable for obtaining durable constructions. Also, the earth has been associated with other materials, often local and natural, as well as minerals, in order to obtain building materials. [0005] One of these materials, known under the name of rammed earth, uses raw earth compacted in a formwork or a banking. The earth is then thrown into the formwork in thin layers of 10 cm to 1m, then manually compacted into the formwork using a pestle.

[0006] This type of material makes it possible to obtain an earth-based wall which is sufficiently porous to allow ideal breathing of the premises it defines. Now, this material is very sensitive to erosion due to its porosity and therefore only offers a very limited hold over time.

[0007] If concrete has established itself for centuries as the reference construction material, new environmental regulations for new buildings will emerge this year in France (RE 2020) and which will lead to rethinking construction. This new regulation will make it necessary to further improve the environmental performance of a building by taking into account not only the insulation but the overall environmental impacts associated with this construction. Thus, Ton will have to take into account all the components of the building, its plot but also the site with the taking into account of the energy consumption of the site, site water consumption and discharge, disposal and treatment of earthworks waste.

[0008] This change therefore requires an in-depth review of the construction processes in order to optimize energy expenditure. [0009] The inventors have now developed a new process for manufacturing an earth-based mortar which not only allows the earth resulting from the construction site to be used but also does without cement. This process, which can be used for both vertical and horizontal surfaces and concrete blocks, considerably reduces the energy consumption of the associated construction and therefore the environmental impact of a site.

[00010] A first object of the invention therefore relates to a method of spraying or injecting an earth-based mortar comprising the steps of:

I) preparation of the mortar by mixing:

[00012] ia) an earth with a particle size of 20 mm or less, preferably less than or equal to 15 mm in a volume proportion of 20 to 55% and, particularly preferably 20 to 40%;

[00013] ib) a binder comprising slag or metakaolin and, optionally lime, in a volume proportion of 15 to 55%, preferably 25 to 50%; [00014] ic) aggregates the particle size of which is between 2 and 20 mm, preferably between 2 and 15 mm, and in a volume proportion of 0 to 20%;

[00015] id) fibers in a volume proportion of between 0 and 30%, preferably between 10 and 30% and, particularly preferably, between 10 and 20%;

[00016] ie) of the crystallizer in a volume proportion of between 1 and 15%, for example between 1 and 8%, preferably between 1 and 4%; and particularly preferably between 2 and 4%; and

[00017] if) water in a volume proportion of between 5 and 20%, of preferably between 5 and 10%.

Ii) pumping the mixture obtained in i); and

[00019] iii) injection of the mixture into a mold or projection of the mixture onto a vertical or horizontal surface. The volume proportion of each component corresponds to the volume occupied by this component relative to the total volume of the mortar mixture.

By mortar is also meant a coating, which can be applied to a surface and having a resistance of at least 5 MPa, an assembly or filling mortar with a resistance of at least 10 MPa, that 'a mortar intended for the manufacture of a load-bearing wall with a resistance of at least 15 MPa.

[00022] The method according to the invention can therefore allow the creation of a plaster as well as a wall.

Advantageously, the mortar prepared by the process according to the invention comprises cement in a volume proportion less than or equal to 1%, preferably less than or equal to 0.5% and, particularly preferably, a volume proportion of 0% cement.

[00024] 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.

[00025] By earth, we mean the earth resulting from earthworks or excavation (quarry), or crushed deconstruction material (excluding topsoil.

By deconstruction material is meant concrete, plaster, stone or even mortar.

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

[00028] This land may therefore have a very great diversity of nature depending on the site from which it comes. We can thus find land integrating gypsum, silt, limestone, silica, clay or even a mixture thereof. Preferably, said earth will incorporate a clay content of 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.

Now, the earth does not come from sand quarries or from aggregates (virgin aggregates) quarries.

[00030] In addition, preference will be given to a soil which has undergone at most a pre-treatment by grinding, sorting (eg depending on 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 remove the elements having a dimension between 10 and 20 mm, preferably between 10 and 15 mm. Note that the earth used has therefore not undergone any chemical pretreatment, such as pretreatment with a surfactant, so as to modify its structure and allow its liquefaction.

[00031] Prior to the use of soil, care will be taken to determine the presence or absence of traces of metallic elements (Pb, As, etc.) so as to prevent any contamination.

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

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

[00034] According to a preferred embodiment, the method according to the invention will therefore preferably comprise a step of sieving the soil prior to step i).

The very great adaptability of the process according to the invention to the different types of existing soil allows it to use the same soil from the site on which the process is implemented.

[00036] 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, of sieving the latter. The term “slag” is understood to mean the slag formed during the melting or production of the metal by liquid means. It is a mixture composed essentially of silicates, aluminates and lime with various metal oxides except iron oxides.

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

By metakaolin is meant the product of a calcination of kaolin and / or kaolin clay.

Preferably, the binder comprises slag and, optionally, lime.

[00041] The lime will preferably be used in a volume proportion of between 0 and 25%, preferably between 1 and 25%, for example between 5 and 20%, and particularly preferably between 10 and 20%.

By lime is meant artificial lime which essentially comprises calcium and magnesium oxide and / or calcium and magnesium hydroxide. Advantageously, the lime is chosen from the group comprising hydraulic lime and air lime.

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

[00045] Preferably, a hydraulic lime NHL 3.5 or NHL 5 will be used. [00046] Preferably, the use of a hydraulic lime NHL 3.5 Z or

NHL 5 Z, insofar as it includes cement.

By aggregates is meant both natural aggregates (eg gravel or sand) and recycled aggregates (eg concrete or crushed mortar).

[00048] Now it is possible to mix the different types of aggregates, natural and recycled, in varying proportions.

As regards the particle size, a particle size of between 4 and 10 mm and, particularly preferably, a particle size of between 4 and 6 mm will be preferred.

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

[00051] In the case where the earth used incorporates aggregates. Then the proportion of aggregates added in addition to the soil 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. %.

[00052] According to yet another preferred embodiment, the method according to the invention will preferably comprise a step prior to step i) of extraction of aggregates and, optionally, of sieving thereof.

By crystallizer, sometimes also called mineralizing, is meant compounds capable of forming, by a reaction qualified as mineralization, crystalline and insoluble complexes with the soluble compounds of the mortar (free lime).

[00054] By way of example of such compounds, mention may be made, for example, of silicate salts, carbonate salts (eg natron), alginate salts

According to a particular embodiment, the crystallizer comprises at least one strong base in proportion so that the pH of the mixture at the end of step i) is equal to or greater than 9.0, preferably greater than or equal to 10.0 and, particularly preferably greater than or equal to 11.0. As a base, there may be mentioned sodium or calcium hydroxide.

[00056] Such crystallizers are known for use in waterproofing concrete, in particular under the names PENETRON, XYPEX, VANDEX, mineralizing agent B HYDRO-MINERAL, etc.

[00057] Preferably, the crystallizer comprises silicate ions capable of forming silicate complexes with calcium hydroxide, in particular calcium, magnesium, sodium or even potassium silicate. Preferably, calcium and / or magnesium silicate will be used.

[00059] Depending on the silicate salt, it will be possible to add a strong base to it or not.

Thus, if the use of sodium silicate does not involve the use of an additional base, it is possible to add sodium or calcium hydroxide in the case of a crystallizer comprising calcium and / or magnesium silicate.

[00061] According to a preferred embodiment of the method according to the invention, step ie) is carried out simultaneously or consecutively with step ib), preferably simultaneously. By fibers is meant both synthetic fibers (eg polypropylene fibers, glass fibers, carbon fibers, etc.) as natural fibers (eg hemp), which fibers can be in any form (elongated or circular), preferably in elongated form.

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

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

[00065] According to a preferred embodiment, natural fibers or plant fibers will be used. To obtain such plant fibers, it is possible to use fiber plants, a large part of which are well known.

For the bast fibers, corresponding to the fiber of the bark, one can cite by way of example hemp, jute, kenaf, barrel vine, flax, nettle, papyrus, esparto , linden fibers, bamboo fibers, Provence cane fibers, seagrass, miscanthus fibers, bagasse, etc.

[00067] For leaf fibers, we can cite Manila hemp (from abaca), pina (from pineapple), agave leaf fiber (eg sisal).

[00068] For fibers originating from seeds or fruit, mention may be made of coir, rice husks or straw or even cotton. Finally, the mortar can integrate other adjuvants such as plasticizers, water-retaining agents, water-repellent agents, biocides, fungicides, dispersants, air entrainer (hunter), setting accelerators , setting retarders, thinners, antifreeze agents or expansion agents.

Of course, each of these adjuvants can be added to the mortar alone or in combination with one or more other adjuvants.

[00071] Stage i) of mixing can be carried out according to techniques well known to those skilled in the art.

[00072] Advantageously, the mixing is carried out using a mixer, in particular a mobile mixer with horizontal or vertical axes allowing the preparation of the mixture on the same site where the wall is to be produced.

If the earth-based mortar cannot be used immediately at the end of step i), it is also possible, by then omitting to add at least the water, to bag the mixture during of 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.

[00074] Step ii) of pumping can be carried out according to techniques well known to those skilled in the art.

This pumping step is performed using pumping means such as a piston pump or a worm pump. 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 'a projection on a vertical surface.

[00077] Such a temperature could 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 (eg friction of the mixture with the surface of the endless screw) .

[00078] 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.

[00079] In fact, the specific features of the mortar obtained allow its industrial use in the manufacture of construction elements such as borders, concrete blocks, paving stones, etc.

By mold of at least one construction element is meant a mold chosen from the group comprising molds for concrete blocks, hollow or solid, for borders, paving stones and slabs. In this case, the method according to the invention can further comprise the step of:

[00082] iv) compression of the mixture injected into a mold for at least one construction element. This compression step is performed by devices well known to those skilled in the art.

[00084] 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.

[00085] Also, the method according to the invention may further comprise the step of: [00086] v) stirring the mixture in the mold.

This stirring step can be carried out by means of vibrating devices positioned in the mold or associated therewith. Examples include vibratory tables or vibrating probes (needles).

[00088] This step can be followed by a step vi) of drying and demolding. [00089] According to another particular embodiment of the method according to the invention, it is intended for projection on a horizontal or vertical surface, preferably on a vertical surface.

[00090] In fact, 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 about ten centimeters and without observing any sagging. It is also possible to carry out successive applications of the mortar according to the invention by applying a recovery time of between 30 minutes to 6 hours between two successive layers, preferably between 1 and 3 hours.

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. Note that this thickness can be achieved by means of one or more applications of the mortar on the surface. Typically, each application will increase the thickness by no more than 10 cm.

Now and preferably, the surface onto which the Earth-based mortar comprises a reinforcing element, which can for example take the form of a frame, which frame can be metallic, plastic (polyethylene, polypropylene, etc.) vegetable (bamboo, Provence cane, etc.) .

[00093] As regards the projection as such, it is carried out by means of devices well known to those skilled in the art. Typically, such a projection is carried out by means of a projection lance placed at the outlet of the pumping means.

[00094] Such a projection lance takes the form of a flexible pipe of suitable section at the end of which a projection nozzle is positioned. 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 than to the driving of said earth-based mortar in view of its projection on a vertical or horizontal surface.

[00095] A second object of the invention is the earth-based mortar as obtained from Tissue in step i) of the process described above. Such a mortar according to comprises:

[00097] a) a soil with a particle size of 20 mm or less, preferably less than or equal to 15 mm in a volume proportion of 20 to 55%, preferably 20 to 40%;

[00098] b) a binder comprising slag or metakaolin and, optionally lime, in a volume proportion of 15 to 55%, preferably 25 to 50%;

[00099] c) aggregates the particle size of which is between 2 and 20 mm, preferably between 2 and 15 mm, and in a volume proportion of 0 to 20%; D) fibers in a volume proportion of between 0 and 30%, preferably between 10 and 30%, and particularly preferably between 10 and 20%;

[000101] e) of the crystallizer in a volume proportion of between 1 and

15%, for example between 1 and 8%, preferably between 1 and 4% and, particularly preferably, between 2 and 4%; and [000102] f) optionally water in a volume proportion of between 5 and 20%, preferably between 5 and 10%.

[000103] The characteristics and proportions of each component of the mortar are as described above. Advantageously, the mortar according to the invention is packaged in a bag and does not include water.

[000105] A third object of the invention relates to a mixture intended for the preparation of a mortar according to the invention, which mixture comprises:

[000106] a) between 90 and 98% by weight of a binder (relative to the total weight of the mixture) comprising slag or metakaolin and, optionally, lime,

[000107] b) between 2 and 10% by weight, preferably between 3 and 8%, by weight of crystallizer (relative to the total weight of the mixture), preferably between 4 and 6%. [000108] Preferably, this mixture does not include soil, aggregates or plant fibers which are intended to be added on the site to produce the earth-based mortar.

Advantageously, the binder comprises slag and, optionally, lime. [000110] The mixture will further comprise between 0 and 50% lime.

[000111] Accordingly, a preferred mixture comprises:

[000112] a1) between 30 and 90% by weight of slag (relative to the total weight of the mixture), preferably between 50 and 85% and, particularly preferably, between 60 and 80%, typically between 70 and 77% , [000113] a2) between 3 and 40% by weight of lime (relative to the total weight of the mixture), preferably between 5 and 20% and, particularly preferably, between 10 and 20%.

[000114] b) between 2 and 10% by weight of crystallizer (relative to the total weight of the mixture), preferably between 3 and 8% and, particularly preferably between 4 and 6%. Preferably, the crystallizer comprises salts of silicates, preferably chosen from the group comprising silicate of calcium, magnesium, sodium and potassium.

[000116] Optionally, the crystallizer further comprises a base, preferably sodium or calcium hydroxide.

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

[000118] A fourth object of the invention relates to a construction element capable of being obtained using a mortar as defined above.

[000119] Such a product can take the form of any construction element, whether concrete block (solid or hollow), borders, paving stones and slabs.

[000120] 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.

[000121] By construction elements, we mean partitions, blocks, concrete blocks (hollow or solid), borders, paving stones, slabs, etc.

By realization is meant the realization by injection or projection.

[000123] Other characteristics, details and advantages of the invention will emerge more clearly from the detailed description given below by way of indication.

[000124] Process for preparing the earth mortar

[000125] The site soil has been sieved beforehand with a 10 mm mesh. [000126] The sieved site soil is then incorporated into the tank of the mixer of a TURBOSOL T20X spraying machine. We then integrate 4/6 gravel, hemp fibers (10 mm) and a rapid mixing of the mixture is carried out for a few minutes (generally about 2 minutes). The water is then incorporated into the mixture and rapid mixing allows the mixture to homogenize. Finally, the binder and the crystallizer are incorporated into the mixture and a longer mixing step is carried out (typically between 3 and 5 minutes) so as to obtain a smooth consistency of the mortar.

[000127] The mixture is then ready to be projected (or injected in the case of preparation construction elements)

[000128] Examples of formulations

[000129] Different formulations of earth mortar have been prepared and have made it possible to arrive at the formula according to the invention. The soils tested included gypsum, quarry waste (limestone), silts and clays.

Certain formulas tested are described in Tables 1 to 4.

[000131] [Table 1]

[000132] [Table 2]

[000133] [Table 3]

[000134] [Table 4]

[000135] Step of projection of the earth mortar [000136] The projection of the earth mortar is then carried out on a previously prepared support.

[000137] In the tests carried out, wooden frames were produced, which frames had a bottom made of OSB plywood panel screwed to the wooden structure and a welded mesh type metal grid positioned in the middle to allow the incorporation of 'elements traditionally used in the building trades (electrical wiring, water supply, etc.).

The projection of the various earth mortars described above was then carried out in two successive layers of 7 to 8 cm. The recovery period between two coats was 30 mins.

We can consider that this time is short because in reality the panels produced on a conventional site are of larger dimensions. This will systematically give a higher recovery time (approximately 1 to 2 hours). [000140] In the end, the filler panels produced in the workshop represented a final thickness of 15 cm. After spraying, the mortar held perfectly and a finish was carried out (rule, float or trowel depending on the panels).

[000141] Properties of the earth mortar

[000142] Earth mortar specimens were produced in order to test its properties.

[000143] The tests carried out are as follows:

[000144] Test on hardened concrete according to standard NF P18-459

[000145] Thermal conductivity test by the metric flux method according to standard NF EN 12667 [000146] Hygrometric performance test by determining the properties of

Hygroscopic sorption. (Sorption and desorption curve) according to standard NF EN ISO 12571.

[000147] Air permeability and water tightness test.

[000148] Compression tests according to standard NF EN 12390-3 (by comparison with control elements).

[000149] Determination of dimensional variations due to humidity of aggregate concrete masonry elements according to standard NF EN 772-14. For each configuration.

[000150] Freeze / Thaw accelerated aging tests according to standard NF EN 771-1 + A1 / CN

Claims

1 A method of spraying or injecting an earth-based mortar comprising the steps of: i) preparation of the mortar by mixing: ia) earth resulting 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 55%; ic) 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) of the crystallizer in a volume proportion of between 1 and 15%; and if) water in a volume proportion of between 5 and 20%; ii) pumping the mixture obtained in i); and iii) injecting the mixture into a mold or spraying the mixture onto a vertical or horizontal surface. 2. The method according to claim 1, characterized in that the mortar prepared by the method according to the invention comprises cement in a volume proportion less than or equal to 1%, preferably less than or equal to 0.5%. 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 comprises silicate of calcium, magnesium, sodium or potassium. 5. The method according to any one of claims I to 4, characterized in that the crystallizer further comprises a strong base, preferably G hydroxide. sodium or calcium. 6. The process according to any one of claims 1 to 5, characterized in that the fibers are synthetic fibers and / or natural fibers. 7. A mortar as defined in any one of claims 1 to 6, characterized in that it comprises: a) a soil 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 55%; c) aggregates with a particle size between 2 and 20 mm, and in a volume proportion of 0 to 20%; d) fibers in a volume proportion of between 0 and 30%; e) of the crystallizer in a volume proportion of between 1 and 15%; and e) optionally water in a volume proportion of between 5 and 20%. 8. A mixture intended for the preparation of a mortar as defined in claim 7, which mixture comprises; al) between 30 and 90% by weight of slag (relative to the total weight of the mixture) a2) between 3 and 40% by weight of lime (relative to the total weight of the mixture); b) between 2 and 10% by weight of crystallizer (relative to the total weight of the mixture), preferably between 3 and 8% and, particularly preferably between 4 and 6%. 9. A construction element capable of being obtained with a mortar as defined in claim 7. 10. A use of a mortar as defined in claim 7 or a mixture of one as defined in claim 8 for the production of earth-based construction elements.