Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/001—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing unburned clay
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/006—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing mineral polymers, e.g. geopolymers of the Davidovits type
  • C04B28/008—Mineral polymers other than those of the Davidovits type, e.g. from a reaction mixture containing waterglass
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
  • C04B28/021—Ash cements, e.g. fly ash cements ; Cements based on incineration residues, e.g. alkali-activated slags from waste incineration ; Kiln dust cements
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
  • C04B28/08—Slag cements
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/24—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing alkyl, ammonium or metal silicates; containing silica sols
  • C04B28/26—Silicates of the alkali metals
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/00034—Physico-chemical characteristics of the mixtures
  • C04B2111/00129—Extrudable mixtures
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/10—Compositions or ingredients thereof characterised by the absence or the very low content of a specific material
  • C04B2111/1037—Cement free compositions, e.g. hydraulically hardening mixtures based on waste materials, not containing cement as such

Definitions

• the invention relates to the field of construction and more particularly that of masonry elements that can be used in construction.
• it relates to a block of compressed concrete comprising a raw clay matrix.
• the invention relates to a method for preparing and using the compressed concrete block.
• Cement is the second most consumed resource in the world, with more than 4 billion tons produced each year in the world. This consumption is constantly increasing, driven by the growing demand for housing and infrastructure. Cement is used in particular for the manufacture of masonry elements such as precast concrete blocks (abbreviated “BBM” or “concrete block”). We count more than 150 references of different concrete blocks, in shape as in composition.
• the prime contractor designing the buildings prescribes cement agglomerates such as hollow manufactured concrete blocks (abbreviated “agglo” in everyday language; also called cinderblock).
• precast concrete blocks with a low surface mass eg less than 600 kg/m 2
• precast hollow concrete blocks replacing shuttered walls because they use less material for the same surface. of load-bearing wall. Thus, they allow a significant reduction of the CO2 carbon footprint.
• precast concrete blocks are among the masonry units, the one with the best quality/price ratio.
• the most common blocks are made of cement concrete or terracotta.
• the cement concrete block is generally composed of 87% aggregates (stones, gravel, sand) from local quarries, 7% cement (limestone and baked clay) and 6% water. They are of usual average weight between 10 and 25 kg (those in cement are heavier than those in terracotta but the cement concrete blocks are often hollow).
• the concrete blocks contain Portland cement or clinkers which are responsible for CO2 emissions in the environment. When they contain clay, it is cooked (metakaolin type), which again leads to the release of CO2 linked to the energy expenditure necessary for this cooking.
• Cement generally Portland cement
• Portland cement is a hydraulic binder which, when mixed with water, hardens and solidifies. After hardening, the cement retains its strength and stability even when exposed to water.
• cements used by the world. Nevertheless, all conventional cements contain a percentage of clinker ranging from 5% for certain blast furnace cements to a minimum of 95% for Portland cement, which is the cement most widely used in the world today.
• Clinker results from the firing of a mixture composed of approximately 80% limestone and 20% aluminosilicates (such as clays). This cooking, the clinkerization, is generally done at a temperature of more than 1200°C, such a cement preparation process therefore involves high energy consumption. Additionally, the chemical conversion of limestone to lime also releases carbon dioxide. As a result, the cement industry generates around 8% of global CO2 emissions.
• self-compacting concretes generally have a different behavior from the concretes used for the manufacture of precast concrete blocks and in particular precast concrete blocks with a low surface mass. It has also been proposed to combine clayey earth with blast furnace slags, but the bricks produced required very long curing times (“Engineering properties of unfired clay masonry bricks” JE Oti et al. Engineering Geology 107 (2009) 130 -139).
• manufactured concrete blocks with a low surface mass are formed during a specific process comprising the use of a mold and a compression step.
• a surface mass eg less than 600 kg/m 2
• superplasticizers from the petrochemical industry are often used, the production of which must be taken into account in the calculation of the carbon footprint (Dawood et al. 2010. Hollow block concrete units production using superplasticizer and pumicite. Australian Journal of Civil Engineering. Volume 6, 2010 - Issue 1). Compounds of natural origin have also been proposed, but they were not able to completely replace Portland cement (Samad et al., 2021.
• Portland cement is an element which appears unavoidable in the manufacture of precast concrete blocks having a reduced surface mass (eg less than or equal to 600 kg/m 2 ).
• a reduced surface mass eg less than or equal to 600 kg/m 2
• the invention aims to overcome these drawbacks.
• the object of the invention is to remedy the drawbacks of the prior art.
• the object of the invention is to propose a masonry element, in particular a compressed concrete block having a low surface mass, good compactability property and a compressive strength compatible with use in the building industry.
• the invention also aims to provide a method for preparing such compressed concrete blocks, said method having reduced CO2 emissions compared to the methods of the prior art.
• the invention aims to overcome these drawbacks.
• the invention relates in particular to a compressed concrete block comprising a matrix raw clay, a composition of calcined metal oxides and aggregates, said compressed concrete block having a surface mass less than or equal to 600 kg/m 2 .
• the invention relates to a block of compressed concrete which can be obtained according to a method according to the invention.
• the invention also relates to a block of compressed concrete obtained according to a process according to the invention.
• the compressed concrete block comprises a raw clay matrix, metal oxides and aggregates.
• the compressed concrete block has a surface mass less than or equal to 600 kg/m 2 and a thickness of at least 15 cm.
• the applicant has developed a process for preparing compressed concrete blocks similar to manufactured concrete blocks, but produced from a binder comprising raw clay, so as to limit the carbon footprint. and having compactability properties making industrialization possible.
• this raw clay advantageously replaces clinker, Portland cement or baked clay.
• the applicant has in particular developed a specific mixture, namely the combined presence of raw clay with metal oxides and an activator, making it possible to manufacture compressed concrete blocks with good performance.
• the inventors have also developed a process for preparing a block of compressed concrete which makes it possible, even in the absence of deflocculant, to achieve sufficient mechanical strength values, that is to say at least equal to 40 kg / cm 2 .
• the latter may optionally include one or more of the following characteristics, alone or in combination:
• Such blocks are easier to handle, in particular for quickly constructing wall planes, such as facade walls or load-bearing walls.
• It has a density less than or equal to 2000 kg/m 3 , preferably less than or equal to 1900 kg/m 3 , more preferably less than or equal to 1800 kg/m 3 .
• It comprises at least 2% by weight of raw clay matrix, preferably at least 2.5% by weight, more preferably at least 3% by weight, and even more preferably at least 4% by weight of matrix raw clay.
• the raw clay matrix comprises at least one clay selected from: kaolinite, bentonite, Montmorillonite, Illite, Smectite, Chlorite, Muscovite, Hallocyte, Sepiolite, Attapulgite and Vermiculite.
• At least part of the raw clay matrix corresponds to excavated earth.
• At least a part of the raw clay matrix corresponds to ground raw clay and has a D50 less than or equal to 500 ⁇ m, preferably less than or equal to 250 ⁇ m, more preferably less than or equal to 100 ⁇ m or even more preferably less than or equal to 50 ⁇ m.
• This crushed raw clay may constitute only a part of the raw clay of the raw clay matrix and can preferably be combined with another raw clay having a different D50. This is advantageously applicable in the context of adding additional raw clay when using excavated earth.
• At least part of the raw clay matrix corresponds to ground raw clay and has a D50 greater than or equal to 0.1 ⁇ m, preferably greater than or equal to 1 ⁇ m, more preferably greater than or equal to 10 ⁇ m or even more preferably greater than or equal to 20 ⁇ m, more preferably greater than 40 ⁇ m.
• At least part of the raw clay matrix corresponds to ground raw clay and has a D50 of between 10 ⁇ m and 500 ⁇ m, preferably between 15 ⁇ m and 200 ⁇ m, more preferably between 20 ⁇ m and 100 ⁇ m pm or even more preferably between 20 pm and 50 pm.
• - It comprises at least 1% by weight of divalent metal oxides, preferably at least 2% by weight, more preferably at least 3% by weight. This can make it possible to obtain compressed concrete blocks having a better mechanical resistance to compression.
• - It has an alkaline activating composition. In particular, it was formed from a binder comprising an alkaline activating composition.
• the mass ratio of metal oxides to the raw clay matrix is between 0.4 and 2.5.
• the aggregates comprise mineral aggregates, the mineral aggregates being preferably selected from fillers, powders, sand, gravel, gravel and their combination.
• the aggregates are predominantly, by weight, mineral aggregates.
• the aggregates are composed of more than 80% by weight of mineral aggregates.
• It has one or more cavities with a volume greater than or equal to 2 cm 3 , preferably with a volume greater than or equal to 4 cm 3 , more preferably with a volume greater than or equal to 6 cm 3 , even more preferably with a volume greater than or equal to 8 cm 3 .
• the volumes correspond to the individual volumes of each cavity.
• It has one or more cavities, preferably said cavity or cavities representing a total volume of at least 30% of the total volume of the compressed concrete block.
• It comprises at least 40% by weight of aggregates, preferably mineral aggregates, preferably at least 60% by weight, more preferably at least 70% by weight, and even more preferably at least 80% by weight .
• the aggregates include a biosourced aggregate, the biosourced aggregate preferably being selected from wood, preferably shavings or fibers, hemp, straw, hemp hemp, miscanthus, sunflower, cattail, corn, flax, rice husks, wheat husks, rapeseed, seaweed, bamboo, cellulose wadding, fiber cloth and their combination.
• the aggregates are predominantly, by weight, vegetable aggregates.
• the aggregates are composed of more than 60% by weight of vegetable aggregates.
• biobased aggregates preferably at least 15% by weight, more preferably at least 20% by weight, and even more preferably at least 35% by weight.
• MBV water buffering capacity
• It includes a deflocculant, preferably an organic deflocculant.
• the compressed concrete block has a compressive strength value after 7 days, as measured by standard NF EN 771-3, of at least 4 MPa.
• the invention relates to a process for preparing a block of compressed concrete having a basis weight less than or equal to 600 kg/m 2 , said process comprising the following steps:
• the invention relates to a method for preparing compressed concrete blocks having a surface mass less than or equal to 600 kg/m 2 , said method comprising the following steps:
• Such a method can advantageously use a ground clay matrix having a D50 preferably less than or equal to 250 ⁇ m, more preferably less than or equal to 100 ⁇ m as measured by methods known to those skilled in the art such as the methods described by ASTM D422-63 or ASTM D6913-04.
• this can improve the mechanical resistance to compression of the compressed concrete block obtained.
• this makes it possible to standardize the quality of the blocks produced and reduce the phenomena of dimensional variations.
• compressed concrete blocks having a surface mass of less than or equal to 600 kg/m2 and preferably a compressive strength at 7 days greater than 0.5 MPa, as measured by the NF standard. EN 771-3.
• the compressive strength of the concrete block is advantageously greater than 2 MPa, preferably greater than 4 MPa when the aggregates are mineral aggregates.
• the aggregates are plant aggregates, it is preferably greater than 0.5 MPa, and more preferably greater than 1 MPa.
• the latter may optionally include one or more of the following characteristics, alone or in combination:
• the mixing step includes a step of premixing the raw clay matrix and the calcined metal oxide composition so as to form a construction binder. This makes it possible to produce a homogeneous binder with a well-distributed clay to improve the performance of the block.
• the mixing step may include a step of hydrating this premix.
• the building binder is mixed with the aggregates and the water during the mixing step, preferably at a building binder content of less than or equal to 250 kg/m 3 of mixing volume. Preferably and like the other measurements, this measurement is indicated in dry weight.
• the mixing step further comprises the addition of an activating composition, preferably an alkaline activating composition.
• an activating composition preferably an alkaline activating composition.
• This addition of an activating composition is preferably carried out during the premixing step. This makes it possible to form a homogeneous binder which will then be mixed with the aggregates and the water.
• the mixing step further comprises the addition of a deflocculant, preferably an organic deflocculant.
• a deflocculant is preferably carried out during the premixing step. This makes it possible to form a homogeneous binder which will then be mixed with aggregates and water. As will be illustrated in the examples, the use of a deflocculant makes it possible to limit the friability of the compressed concrete block.
• the mass ratio of the composition of calcined metal oxides to the raw clay matrix is between 0.4 and 2.5.
• It includes a step of curing the compressed concrete blocks obtained, preferably in a curing chamber.
• It further comprises a heating step, between 20°C and 90°C, preferably between 40°C and 80°C.
• This heating step is preferably included during a curing step which can be humid, for example at more than 80% relative humidity. This aims to harden the resulting compressed concrete blocks.
• the mixing step involves extruding the mixture.
• the raw clay matrix comprises at least one clay selected from: Kaolinite, Bentonite, Montmorillonite, Illite, Smectite, Chlorite, Muscovite,
• the raw clay matrix comprises at least one raw clay from the smectite family, and the at least one raw clay from the smectite family represents more than 20% by weight of the raw clay matrix. As will be described, this makes it possible to combine mechanical properties and water buffering capacity.
• the raw clay matrix contains at least 50% by dry weight of kaolinite and/or illite. As will be described, this allows the best results to be obtained in terms of speed of setting and mechanical resistance at 20 hours.
• - at least part of the raw clay matrix corresponds to ground raw clay and has a D50 greater than or equal to 0.1 ⁇ m as measured by standard ASTM D422-63. Preferably, it has a D50 greater than or equal to 1 ⁇ m, more preferably greater than or equal to 10 ⁇ m or even more preferably greater than or equal to 20 ⁇ m, more preferably greater than 40 ⁇ m.
• the D50 can be measured by any technique known to those skilled in the art such as ASTM D422-63 or ASTM D6913-04 (2009).
• - at least part of the raw clay matrix corresponds to ground raw clay and has a D50 of between 10 ⁇ m and 500 ⁇ m as measured by standard ASTM D422-63.
• the D50 has a D50 of between 15 ⁇ m and 200 ⁇ m, more preferably between 20 ⁇ m and 100 ⁇ m or even more preferably between 20 ⁇ m and 50 ⁇ m.
• the D50 can be measured by any technique known to those skilled in the art such as ASTM D422-63 or ASTM 06913-04 (2009).
• the aggregates comprise mineral aggregates, the mineral aggregates being preferably selected from fillers, powders, sand, gravel, gravel, fossilized aggregates and their combination.
• the mixture comprises at least 40% by weight of mineral aggregates, preferably at least 60% by weight, more preferably at least 70% by weight, and even more preferably at least 80% by weight.
• the aggregates include biosourced aggregates, the biosourced aggregates being preferably selected from wood, preferably shavings or fibers, hemp, straw, hemp hemp, miscanthus, sunflower, cattail, corn, flax , rice husks, wheat husks, rapeseed, seaweed, bamboo, cellulose wadding, fiber cloth, and a combination thereof.
• the mixture comprises at least 10% by weight of biobased aggregates, preferably at least 15% by weight, more preferably at least 20% by weight, and even more preferably at least 35% by weight.
• the invention relates to a use of a compressed concrete block according to the invention for the production of masonry works; in addition with a mortar which can advantageously be formulated from a binder based on raw clay, preferably a binder comprising at least 20% by weight of raw clay such as those defined in WO2020141285 and WO2020178538.
• the invention relates to a masonry structure comprising a plurality of compressed concrete blocks according to the invention.
• the masonry structure according to the invention could, for example, take the form of a facade wall or a load-bearing wall.
• Figure 1 shows a diagram of a process for preparing a construction element according to the invention, preferably a compressed concrete block.
• Figure 2 shows an illustration of compressed concrete blocks according to the present invention.
• Figure 3 shows an illustration of compressed concrete blocks according to the present invention.
• each block in the flow charts or block diagrams may represent a system, or a device.
• the functions associated with the blocks may appear in a different order than that shown in the figures.
• two blocks shown successively may, in fact, correspond to actions performed substantially simultaneously.
• Each block in the block diagrams and/or flowchart, and combinations of blocks in the block diagrams and/or flowchart can be implemented by special hardware systems that perform the specified functions or acts.
• % by weight in connection with the element of masonry, or in connection with the compressed concrete block, must be understood as being a proportion in relation to the dry weight of the masonry unit or the compressed concrete block.
• the dry weight corresponds to the weight before the addition of water, for example necessary for the formation of the masonry unit.
• clay matrix means one or more rocky materials based on hydrated silicates or aluminosilicates of lamellar structure, said clay matrix being composed of fine particles generally originating from the alteration of silicates with a three-dimensional framework, such as feldspars.
• a clay matrix may thus comprise a mixture of such rocky materials which may for example consist of kaolinite, illite, smectite, bentonite, chlorite, vermiculite, or mixtures thereof.
• a concrete block can correspond within the meaning of the invention to a constructive element formed from a mixture of aggregates, minerals or plants, possibly including sand, construction binder and water.
• raw clay matrix corresponds in the sense of the invention to a clay matrix that has not undergone a calcination step. In particular, that is to say that it has not undergone any prior heat treatment. For example, this corresponds to a clay matrix that has not undergone a temperature rise greater than 300°C, preferably greater than 200°C and more preferably a temperature greater than 150°C. Indeed, the raw clay matrix can undergo a heating step requiring a rise in temperature generally substantially equal to or less than 150°C, but no calcination step.
• a raw clay matrix may preferably comprise a mixture of rocky materials which may for example comprise kaolinite, illite, smectite, micas such as muscovite, bentonite, chlorite, vermiculite, or their mixtures.
• a “deflocculating agent”, “deflocculating agent” or “deflocculating agent”, can correspond to a compound capable of dissociating aggregates and colloids, in particular in aqueous suspension.
• Deflocculating agents have for example been used in the context of drilling or oil extraction to make the clay more fluid and facilitate extraction or drilling.
• composition of metal oxides can refer to the meaning of the invention to a composition comprising metal oxides such as aluminates.
• the composition of metal oxides comprises more than 25% by weight of metal oxides, preferably more than 30% by weight of metal oxides, more preferably more than 40% by weight of metal oxides and even more preferably more than 45% by weight of metal oxides.
• the metal oxide composition comprises more than 2% by weight of aluminate, preferably more than 5% by weight of aluminate, more preferably more than 7% by weight of aluminate and even more preferably more than 10% by weight of aluminate.
• the metal oxides can correspond to, or include, alkaline earth metal oxides.
• the metal oxide composition may comprise more than 10% by weight calcium oxide, preferably more than 20% by weight calcium oxide, more preferably more than 25% by weight calcium oxide and even more preferably more than 30% by dry weight of calcium oxide.
• the metal oxide composition may include chemical species that are not metal oxides.
• the metal oxide composition may comprise metalloid oxides with, for example, more than 10% by weight of metalloid oxide, preferably more than 20% by weight of metalloid oxide, more preferably more than 25% by weight of metalloid oxide and even more preferably more than 30% by weight of metalloid oxide. These mass concentrations can easily be measured by a person skilled in the art using conventional techniques for assaying metal oxides or metalloid oxides.
• composition of metal oxides refers to a composition comprising more than 50%, preferably more than 70%, more preferably more than 80% and even more preferably more than 90% of metal oxides and/or metalloid oxides, including aluminates.
• a composition of metal oxides will correspond to a slag obtained from metallurgy, such as a slag from blast furnaces or even fly ash.
• the “metal oxide composition” is preferably a calcined metal oxide composition. That is to say, it has undergone a high temperature stage. This high temperature step can be natural or artificial, in this case it is a high temperature treatment.
• the high temperature step can for example correspond to a treatment at a temperature greater than or equal to 500° C., preferably greater than or equal to 750° C. and more preferably greater than or equal to 900° C.; and even more preferably above 1000°C.
• the metallic oxide composition of a composition or a construction element can be determined by X-ray diffractometry (“X-ray Diffraction-Based Quantification of Amorphous Phase in Alkali-Activated Blast Furnace Slag” June 2021 Advances in Civil Engineering Materials; “Iron speciation in blast furnace slag cements” Cernent and Concrete Research, Volume 140, February 2021, 106287).
• binder or "construction binder” within the meaning of the invention can be understood as a formulation making it possible to ensure the agglomeration of materials between them, in particular during the setting, then the hardening of a building material. Thus, it makes it possible in particular to ensure the agglomeration of sand and other aggregates with the constituents of the binder.
• the binder according to the invention is in particular a hydraulic binder, that is to say that the hardening takes place in contact with water.
• Portland cement corresponds to a hydraulic binder composed mainly of hydraulic calcium silicates, the setting and hardening of which is made possible by a chemical reaction with water.
• Portland cement generally contains at least 95% clinker and a maximum of 5% secondary constituents such as alkalis (Na 2 0, K 2 0), magnesia (MgO), gypsum (CaSC>4 2 H 2 0 ) or various trace metals.
• moisture buffer value or "MBV” for "moisture buffer value” according to Anglo-Saxon terminology, represents the ability of a material to exchange moisture with its environment. It makes it possible to estimate the dynamic hygrothermal behavior of the material in question and is used to determine the thermal comfort in the field of construction and more particularly the regulation of the interior humidity of a room or a building.
• the MBV will be relative to the constituent concrete of the block and not to the block as a whole.
• the MBV is expressed in g/m 2 .%RH and indicates the average quantity of water which is exchanged by sorption or desorption when the surfaces of the material are subjected to variations in relative humidity (RH) over a given time.
• the water buffer value can be measured by any method known to those skilled in the art.
• the person skilled in the art may refer to the method described in “Durability and hygroscopic behavior of biopolymer stabilized earthen construction materials” Construction and Building Materials 259 (2020).
• the samples (concrete for compressed concrete block according to the invention) could be placed in a climatic chamber at 23° C. and 33% relative humidity and are left until they have a constant mass (for example a chamber climatic model MHE 612). Under these conditions, the samples are equilibrated after 15 days of storage. The samples are then exposed to cycles of high humidity (75% RH for 8 h) then a cycle of low relative humidity (33% RH for 16 h). Samples are weighed at regular intervals with a laboratory scale accurate to 0.01g. After two stable cycles, the samples left the climatic chamber.
• S is the total exposure area and D%RH is the difference between humidity levels.
• substantially equal within the meaning of the invention corresponds to a value varying by less than 20% with respect to the compared value, preferably by less than 10%, even more preferably by less than 5% .
• excavated clay soil corresponds in the sense of the invention to a clay soil obtained following a stage where the soil has been dug, for example during regularization and/or earthworks operations, with a view to to build, build or fill.
• the excavated clay soil may or may not be moved outside the production site.
• the excavated earth is used on the production site or at a distance of less than 200 km, preferably less than 50 km.
• the clayey earth excavated in the context of the invention is raw excavated clayey earth, that is to say that it has not undergone a calcination step.
• this corresponds to a clay soil which has not undergone a temperature rise above 300°C, preferably above 200°C and more preferably a temperature above 150°C.
• the raw clay soil can undergo a drying step requiring a rise in temperature generally substantially equal to 150° C. but no calcination step.
• a calcination step could for example correspond to a heat treatment at more than 600° C. for several seconds.
• Clay as conventionally used has a relatively constant particle size profile with sizes below 2 ⁇ m. Excavated clay soil can have different grain size profiles.
• an excavated clay soil may comprise particles of a size greater than 2 ⁇ m, preferably greater than 20 ⁇ m, preferably greater than 50 ⁇ m and for example greater than 75 ⁇ m as determined according to the ASTM standard. D422-63.
• the excavated clay soil does not contain any aggregate larger than 2 cm as determined according to standard NF EN 933-1.
• the term “clinker” relates to a constituent of cement and comes from the firing of a mixture composed of substantially 80% limestone and 20% aluminosilicates (such as clays). This cooking, clinkering, is generally done at a temperature of more than 1200°C, which is particularly energy-intensive and generates high greenhouse gas emissions. Clinker is generally ground and then added with blast furnace slag to produce cement.
• the expression “surface mass” can relate in the sense of the invention to a mass per unit surface. Its unit of measurement in the International System of Units is the kilogram per square meter (kg/m 2 or kg rrr 2 ). In the context of the invention, it makes it possible to express the mass of the compressed concrete blocks as a function of the construction surface concerned (eg the surface of a section of wall). For example, a compressed concrete block according to the invention of 20 * 20 * 50 will have a surface of 1000 cm 2 . It will therefore take 10 blocks of compressed concrete to make 1 m 2 of surface. If the compressed concrete blocks weigh 20 kg each then the surface mass of the compressed concrete blocks according to the invention will be 200 kg/m 2 .
• density can relate in the sense of the invention to the ratio of the mass of a compressed concrete block to its volume. Here is considered in particular the mass of the concrete used in relation to its volume.
• the mixtures included at least 300 kg/m 3 of Portland cement. That made it possible to preserve the qualities of compaction of the blocks, and compactability of the concrete.
• the invention relates in particular to a compressed concrete block comprising a raw clay matrix, a composition of calcined metal oxides and aggregates.
• this block of compressed concrete advantageously has a surface mass less than or equal to 600 kg/m 2 .
• a compressed concrete block according to the invention has a high quantity of raw clay matrix, a mechanical strength at 7 days generally greater than or equal to 20 kg/cm 2 , preferably greater than or equal to equal to 30 kg/cm 2 , more preferably greater than or equal to 40 kg / cm 2 measured according to standard NF EN 771 -3 / CN, and for certain embodiments, an MBV greater than 0.7, so preferably greater than 1, and more preferably greater than 1.3 and even more preferably greater than 1.5.
• the invention relates to a masonry element and in particular to a compressed concrete block. Furthermore, the invention relates to a masonry element obtained, or likely to be obtained, from a preparation process according to the present invention.
• the masonry element may have a width of at least 5 cm, a height of at least 15 cm and a length of at least 30 cm.
• the masonry element or compressed concrete block may take the form of screen walls.
• the masonry element may also have a width (or thickness) of at least 10 cm, preferably at least 15 cm, more preferably at least 20 cm.
• the compressed concrete block may take the form of a concrete block of substantially 50 x 20 x 15 cm or even 50 x 20 x 20 cm.
• the constructive element can be used to make exterior walls.
• the walls formed with the masonry elements may be load-bearing walls or may be coupled to a post-beam frame, for example made of wood or reinforced concrete.
• the masonry unit may take the form of bricks with, for example, the following dimensions: width of at least 5 cm, height of at least 5 cm and length of at least 20 cm.
• the masonry unit advantageously does not contain Portland cement.
• the masonry unit would remain new compared to the literature if it behaved contrary to the solutions proposed for concrete blocks compressed with a small quantity of Portland cement.
• the masonry element does not comprise Portland cement or it comprises for example less than 5% by weight of Portland cement, preferably less than 4% by weight of Portland cement, more preferably less than 2% by weight of Portland cement, and even more preferably less than 1% by weight of Portland cement (i.e. from 0% to ⁇ 1%).
• the masonry element does not include clinker.
• the masonry element would remain new compared to the literature if it behaved contrary to the solutions proposed for concrete blocks compressed with a low quantity of clinker.
• the masonry element does not comprise clinker or it comprises for example less than 5% by weight of Clinker, preferably less than 4% by weight of Clinker, more preferably less than 2% by weight of Clinker, and even more preferably the masonry unit comprises less than 1% by weight of Clinker (i.e. from 0% to ⁇ 1%).
• the masonry unit does not comprise baked clay.
• the masonry unit does not include of fired clay or it comprises for example less than 5% by weight of fired clay, preferably less than 4% by weight of fired clay, more preferably less than 2% by weight of fired clay, and Even more preferably, the masonry unit comprises less than 1% by weight of fired clay (ie from 0% to ⁇ 1%).
• the masonry unit according to the invention has a compressive strength value on cylinders at 7 days, as measured by standard NF EN 771-3, of at least 4 MPa.
• the masonry element according to the invention has a resistance value compression resistance value from sclerometric index measurements, such as according to standard NF EN 13791 / CN, of at least 10 MPa, preferably 12, even more preferably 15 MPa.
• the masonry unit according to the invention in particular the compressed concrete block, has a basis weight less than or equal to 600 kg/m 2 .
• Such a surface mass in combination with the presence of raw clay, makes it possible to reduce the carbon footprint of a construction based on a masonry element according to the invention.
• the surface mass of the masonry element according to the invention, in particular the compressed concrete block is less than or equal to 400 kg/m 2 , more preferably less than or equal to 300 kg /m 2 , more preferably less than or equal to 200 kg/m 2 .
• the surface mass of the masonry element according to the invention, in particular the compressed concrete block is greater than or equal to 20 kg/m 2 .
• the mass per unit area of the masonry unit according to the invention may be between 10 kg/m 2 and 600 kg/m 2 , preferably between 20 kg/m 2 and 500 kg/m 2 , and even more preferably 30 kg/m 2 and 400 kg/m 2 .
• the concrete constituting a compressed concrete block according to the invention may have a reduced density compared to other compressed concrete blocks.
• the concrete which constitutes the compressed concrete block according to the invention may have a density less than or equal to 2000 kg/m 3 , preferably less than or equal to 1900 kg/m 3 , more preferably less than or equal to 1800 kg/ m3 .
• the masonry unit according to the invention may have one or more cavities.
• the surface mass of a masonry element according to the present invention may be reached by the presence of very low density aggregate or by the presence of one or more cavities. These presences of very low density aggregate or of one or more cavities require good compaction properties made possible by the present invention.
• the cavity or cavities have a total volume of at least 30% of the total volume of the masonry unit as defined by the planes forming the periphery of the masonry unit. More preferably, the cavity or cavities have a total volume of at least 45% of the total volume of the masonry unit and even more preferably of at least 60% of the total volume.
• the cavity or cavities may be open cavities or closed cavities.
• the cavities will have a single opening.
• the masonry unit will comprise several open cavities, said open cavities preferably having a single opening.
• the masonry unit will have several closed cavities.
• the masonry unit according to the present invention comprises a raw clay matrix, a composition of calcined metal oxides and aggregates.
• the masonry unit according to the present invention was formed from a raw clay matrix, a composition of calcined metal oxides and aggregates.
• a masonry unit according to the present invention will logically comprise a raw clay matrix, metal oxides and aggregates.
• the raw clay matrix may for example comprise at least one mineral species selected from: Illite, Kaolinite, Smectite, Bentonite, Vermiculite, Chlorite, Muscovite, Halloysite, Sepiolite, and Attapulgite.
• the smectite family includes montmorillonites and bentonite.
• the raw clay matrix comprises at least two types of clay selected from: Illite, Kaolinite, Smectite, Bentonite, Vermiculite, Chlorite, Muscovite, Halloysite, Sepiolite, and Attapulgite.
• the clay matrix raw contains at least one mineral species selected from: Kaolinite, Illite, Smectite, Bentonite, Chlorite and Vermiculite.
• Table 1 below presents the chemical characteristics of these mineral species.
• a construction binder and then a masonry element according to the invention will comprise at least two different types of clay and will comprise smectite, kaolinite, and/or the illite.
• the type of clay can be determined by methods known to those skilled in the art. In particular, it will be possible to use X-ray diffractometry. For example, the following conditions may be used:
• Diffractometer for example a BRUKER D8 ADVANCE (Bragg-Brentano Geometry); for example with the following settings: Copper tube (l Ka1 « 1.54 ⁇ ) Generator power: 40 kV, 40 mA; Primary optics: fixed slit 0.16°; Soller's cleft 2.5°; Secondary optics: Soller slit 2.5°; LynXeye XE-T Detector
• a masonry unit according to the invention in particular the compressed concrete block according to the invention, comprises at least 1% by weight of raw clay matrix, preferably at least 2% by weight of matrix raw clay matrix, more preferably at least 3% by weight of raw clay matrix and even more preferably at least 4% by weight of raw clay matrix, for example, at least 5% by weight of raw clay matrix or at least 10% by weight of raw clay matrix.
• the inventors have in particular succeeded in producing compressed concrete blocks having an improved visual appearance compared to conventional compressed concrete blocks thanks to the addition of a raw clay matrix.
• a binder used to form a masonry unit according to the invention may comprise at least 5% by weight of raw clay matrix, preferably at least 10% by weight of raw clay matrix, more preferably at least 15% by weight of raw clay matrix and even more preferably at least 20% by weight of raw clay matrix, for example, at least 25% by weight of raw clay matrix or at least 30% by weight of raw clay matrix.
• a masonry unit according to the invention in particular the compressed concrete block according to the invention, comprises at most 90% by weight of raw clay matrix, more preferably at most 80 % by weight of raw clay matrix, more preferably at most 70% by weight of raw clay matrix, more preferably at most 60% by weight of raw clay matrix.
• Such quantities of raw clay matrix can be achieved in particular when the raw clay matrix corresponds to an excavated clay soil.
• a binder used to form a masonry unit according to the invention, in particular the compressed concrete block according to the invention may comprise at most 60% by weight of raw clay matrix, preferably at most 55% by weight of raw clay matrix, more preferably at most 50% by weight of raw clay matrix and even more preferably at most 45% by weight of raw clay matrix.
• a masonry unit according to the invention in particular the compressed concrete block according to the invention, may comprise between 1 and 90% by weight of raw clay matrix, for example between 3 and 90% by weight of raw clay matrix, preferably between 3 and 50% by weight or between 3 and 40% by weight of raw clay matrix, more preferably between 4 and 35% by weight of raw clay matrix.
• the raw clay matrix of a masonry unit according to the invention comprises at least 20% by weight of smectite, illite and/or kaolinite, for example at least 30% by weight of smectite, Illite and/or Kaolinite, preferably at least 40% by weight of smectite, Illite and/or Kaolinite, more preferably at least 50% by weight of smectite, Illite and/or Kaolinite and even more preferably at least 60% by weight of smectite, Illite and/or Kaolinite.
• the percentage by weight corresponding to the cumulative percentage of smectite, Illite and Kaolinite.
• a clay matrix according to the invention may comprise between 20 and 80% by weight of smectite, Illite and/or Kaolinite, preferably between 30 and 70% by weight of smectite, Illite and/or Kaolinite or between 40 and 60% by weight of smectite, Illite and/or Kaolinite, more preferably between 40 and 60% by weight of smectite, Illite and/or Kaolinite.
• the smectite may be Montmorillonite.
• the raw clay matrix of a construction binder according to the invention comprises at least one raw clay from the smectite family and at least one other raw clay selected from Kaolinite, Illite, Chlorite and Vermiculite. Even more preferably, the raw clay matrix of a construction binder according to the invention comprises smectite and at least one other raw clay selected from Kaolinite, Illite, Bentonite, Montmorillonite, Chlorite and Vermiculite.
• the raw clayey matrix may preferably correspond at least in part to an excavated clayey earth, preferably an uncalcined excavated clayey earth, such as a raw excavated clayey earth.
• the clay matrix may comprise particles of size greater than 2 ⁇ m, preferably greater than 20 ⁇ m, preferably greater than 50 ⁇ m and for example greater than 75 ⁇ m as determined according to standard ASTM D422- 63.
• the clay matrix does not contain any aggregate of a size greater than 2 cm as determined according to standard NF EN 933-1.
• the excavated clay soil may advantageously have been pretreated, said pretreatment being selected from: grinding, sorting, sieving and/or drying of the excavated clay soil.
• the pre-processing can for example comprise a fractionation.
• the clay matrix may comprise at least 2% by weight of silt particles, preferably at least 4% by weight, more preferably at least 6% by weight.
• the silt particles are in particular particles having a diameter of between 2 ⁇ m and 50 ⁇ m.
• part of the raw clay matrix can correspond to crushed raw clay.
• part of the raw clay matrix may have a D50 of less than or equal to 500 ⁇ , preferably less than or equal to 250 ⁇ , more preferably less than or equal to 100 ⁇ or even more preferably less than or equal to at 50 p.m.
• At least a portion of the raw clay matrix may have a D50 greater than or equal to 0.1 ⁇ m, preferably greater than or equal to 1 ⁇ m, more preferably greater than or equal to 10 ⁇ m or more preferably. even more preferably greater than or equal to 20 ⁇ m, more preferably greater than 40 ⁇ m. This makes it possible to limit the constraints on industrial production tools dedicated to grinding.
• At least part of the raw clay matrix may have a D50 of between 10 ⁇ m and 500 ⁇ m, preferably between 15 ⁇ m and 200 ⁇ m, more preferably between 20 ⁇ m and 100 ⁇ m. or even more preferably between 20 ⁇ m and 50 ⁇ m.
• a clay ground in such a way as to reach such diameters can make it possible to improve the compaction of the compressed concrete blocks according to the invention.
• a compressed concrete block according to the invention can advantageously comprise a raw clay matrix which is composed of raw clay coming from ground excavated earth, for example with a D50 greater than 500 ⁇ m (it is not necessary to finely grind it) on the one hand and a finely ground raw clay (cf. D50 presented above).
• the raw clay matrix comprises kaolinite and/or illite. It is when the raw clay matrix includes these clays (one or more) that the best results in terms of speed of setting and mechanical resistance at 20 hours are obtained.
• a raw clay matrix according to the present invention may comprise at least 25% kaolinite and/or illite. Nevertheless, raw clay matrices comprising a majority of kaolinite and/or illite will be preferred in the context of the present invention. This may for example correspond to a clay matrix comprising more than 25% kaolinite and more than 25% illite, or even a clay matrix comprising more than 40% kaolinite and more than 10% illite. Thus, a raw clay matrix according to the present invention will preferably comprise at least 50% by dry weight of kaolinite and/or illite, more preferably at least 70% by dry weight of kaolinite and/or illite.
• a clay matrix according to the invention may comprise between 20 and 80% by weight of kaolinite and/or illite, preferably between 30 and 70% by weight of kaolinite and/or illite or between 40 and 60% by weight of kaolinite and/or illite, more preferably between 40 and 60% by weight of kaolinite and/or illite.
• the raw clay matrix comprises smectite, preferably Montmorillonite.
• the smectite family includes montmorillonites and bentonite.
• the clay matrix comprises at least 10% by weight of smectite, preferably montmorillonite, more preferably at least 20% by weight.
• the raw clay matrix comprises at least one raw clay from the smectite family and in particular when the at least one raw clay from the smectite family represents more than 20% by weight of the raw clay matrix, preferably at least 30% by weight of the raw clay matrix, then the compressed concrete block formed combines mechanical properties and water buffering capacity. This is particularly the case when the aggregates contain vegetable aggregates.
• composition of calcined metal oxides according to the invention makes it possible to reinforce the bonds between the sheets of clay so as to provide its mechanical properties to the compressed concrete block.
• a composition of calcined metal oxides advantageously comprises metal oxides selected from: iron oxides such as FeO, Fe 3 Ü 4 , Fe2Ü3, alumina Al 2 O 3 , manganese (II) oxide MnO , titanium (IV) oxide T1O 2 , magnesium oxide MgO and mixtures thereof.
• a calcined metal oxide composition can also include aluminosilicates.
• the calcined metal oxide composition is, for example, selected from blast furnace slags, pozzolans such as volcanic ash, fly ash, silica fume or metakaolin, ash from plant materials such as rice ash, bauxite residues or combinations thereof.
• the composition of silicate and metal oxides is for example selected from blast furnace slags, pozzolans such as volcanic ash, fly ash, silica fume, ash from vegetable matter such as ash from rice, bauxite residues or combinations thereof.
• the metal oxides are transition metal oxides.
• the metal oxides can preferably come from a composition of blast furnace slags, for example formed during the production of cast iron from iron ore.
• the masonry unit comprises at least 1% by dry weight of metal oxides, more preferably at least 2% by weight, even more preferably at least 3% by weight.
• a masonry unit according to the invention may comprise at least 2% by dry weight of a composition of blast furnace slags.
• a masonry unit according to the invention will also comprise at least 3% by weight of at least one metal oxide corresponding to the oxide of a metal having at least two valence electrons.
• the at least 3% by weight can be formed from several different metal oxides. These metal oxides may come from several sources.
• the metal oxides formed with a metal having at least two valence electrons will be contained in the activation composition and/or in the calcined metal oxide composition.
• the masonry unit according to the invention comprises at least 3% by weight of at least one metal oxide corresponding to the oxide of a metal having at least two valence electrons, more preferably at least 4% by weight.
• a binder for a masonry unit according to the invention preferably comprises at least 5% by dry weight of metal oxides, more preferably at least 10% by dry weight of metal oxides and even more preferably at least 15% by dry weight of metal oxides.
• a binder for a masonry unit according to the invention preferably comprises at most 70% by dry weight of metal oxides, more preferably at most 60% by dry weight of metal oxides and even more preferably at most 50% by dry weight of metal oxides .
• a binder for a masonry unit according to the present invention may comprise less than 30% by dry weight of metal oxides, preferably less than 20%, more preferably less than 10%.
• the inventors have identified that certain ratio values between the mass quantity of calcined metal oxide composition and the mass quantity of raw clay matrix made it possible to improve the performance of a compressed concrete block thus formed.
• the calcined metal oxide composition and the raw clay matrix are mixed to form a binder for masonry unit concrete such that a mass ratio of the calcined metal oxide composition to the raw clay matrix is between 0.2 and 3, preferably 0.4 and 2.5, more preferably 0.5 and 2.
• the calcined metal oxide composition and the raw clay matrix are mixed to form a binder for masonry unit concrete so that a mass ratio of metal oxides to the clay content is between 0.2 and 3, preferably 0.4 and 2.5; more preferably 0.5 and 2; and even more preferably 0.66 and 2.
• the composition of calcined metal oxides represents from 20% to 70% by dry weight of the binder constituting the concrete of the masonry unit.
• the composition of calcined metal oxides represents from 30% to 45% by dry weight of the binder constituting the concrete of the masonry unit. More preferably, the composition of calcined metal oxides represents from 55% to 70% by dry weight of the binder constituting the concrete of the masonry unit.
• a masonry unit according to the invention in particular the compressed concrete block according to the invention, comprises at least 1% by weight of a composition of calcined metal oxides, preferably at least 2 % by weight of a calcined metal oxide composition, more preferably at least 3% by weight of a calcined metal oxide composition and even more preferably at least 4% by weight of a calcined metal oxides.
• Alkaline activating composition [0107]
• the activating composition in combination with the composition of calcined metal oxides, preferably reinforced by the deflocculating agent, will allow the constitution of a network between the layers of clay which will bring its mechanical properties compressed concrete block according to the invention.
• the masonry element, and preferably the compressed concrete block comprises an alkaline activating composition.
• the concrete of the compressed concrete block according to the invention was formed from a binder incorporating an alkaline activating composition.
• the activating composition is an alkaline activating composition. It then preferably comprises comprises at least one base, such as a weak base or a strong base.
• the alkaline activating composition may preferably comprise one or more compounds having a pKa greater than or equal to 8, more preferably greater than or equal to 10, more preferably greater than or equal to 12, even more preferably greater than or equal to equal to 14.
• the activating composition may comprise sulphates, hydroxides, carbonates, silicates, lactates, organophosphates, lime or combinations thereof.
• the activation composition comprises hydroxides and silicates.
• the activating composition may comprise a mixture of sodium hydroxide and sodium silicate.
• the activating composition includes silicates, the percentage of silicate in the mixture for masonry unit coming from the activating composition and the percentage of silicate in the mixture for masonry unit coming from the calcined metal oxide composition are accounted for separately.
• the activating composition may comprise a mixture of sodium sulphate and sodium chloride.
• the activation composition comprises silicates and carbonates.
• the activating composition may comprise a mixture of sodium or potassium silicate and sodium or potassium carbonate.
• the alkaline activating composition comprises hydroxides.
• the activation composition comprises an oxide of a metal having at least two valence electrons.
• the activating composition may comprise at least 40% by weight of at least one metal oxide corresponding to the oxide of a metal having at least two valence electrons.
• the at least 40% by weight may correspond to several different metal oxides.
• the activation composition preferably when the latter is an alkaline activation composition, may comprise a single oxide of a metal having at least two valence electrons or more than 50% by weight of this metal oxide.
• the activation composition comprises at least 50% by weight of at least one metal oxide corresponding to the oxide of a metal, or of an alkaline earth, having at least two valence electrons, more preferably at least 60% by weight; even more preferably at least 80% by weight.
• the activating composition may comprise an organophosphorus compound such as sodium tripolyphosphate.
• the organophosphorus compound represents at least 2% by weight of the construction binder.
• the activation composition comprises a lactate such as sodium, potassium and/or lithium lactate.
• the activating composition can be a liquid composition.
• the activating composition can be an aqueous composition.
• its use can be combined with the addition of water when forming a mixture for a masonry unit.
• the activating composition is in solid form, for example in powder form.
• the indicated percentage of alkaline activating composition corresponds to the dry weight of the composition.
• the activating composition is for example present at a content of at least 0.1% by dry weight of the masonry element, preferably at least 0.2% by dry weight of the element. of masonry.
• the binder used to form the concrete of the masonry unit comprises from 0.2% to 50% by dry weight of an activating composition. More preferably, it comprises from 2% to 40% by dry weight of an activating composition. Even more preferably, it comprises from 10% to 25% of an activating composition.
• the binder for masonry unit may comprise from 20% to 40% by weight of an alkaline activating composition. It is particularly the case when the alkaline activating composition comprises hydroxides and silicates.
• the compressed concrete block based on construction binder may comprise from 2% to 10% by dry weight of an activating composition. This is particularly the case when the alkaline activating composition comprises carbonates.
• the binder for the masonry element, or the binder for the compressed concrete block, when its preparation has integrated the addition of an alkaline activating composition will preferably comprise at least 0.1% by weight of sodium or potassium, more preferably at least 0.2% by weight sodium or potassium.
• the present invention does not require the mandatory presence of deflocculant to allow the manufacture of compressed concrete blocks that meet market expectations.
• the presence of one or more deflocculants can improve the manufacturing performance of compressed concrete blocks according to the invention.
• the masonry element, and preferably the compressed concrete block comprises a deflocculant, advantageously an organic deflocculant.
• the deflocculating agent is in particular a nonionic surfactant such as a polyoxyethylene ether.
• a nonionic surfactant such as a polyoxyethylene ether.
• the polyoxyethylene ether can for example be selected from: a poly(oxyethylene) lauryl ether.
• the deflocculating agent can also be an anionic agent such as an anionic surfactant.
• the anionic agent can be selected from: alkylaryl sulphonates, aminoalcohols, fatty acids, humates (e.g. sodium humates), carboxylic acids, lignosulphonates (e.g. sodium lignosulphonates), polyacrylates, carboxymethylcelluloses and mixtures thereof.
• the deflocculating agent can also be a polyacrylate. It can then be selected, for example, from sodium polyacrylate and ammonium polyacrylate.
• the deflocculating agent can also be an amine selected, for example, from: 2-amino-2-methyl-1-propanol; mono-, di- or triethanolamine; them isopropanolamines (1-amino-2-propanol, diisopropanolamine and triisopropanolamine) and N-alkylated ethanolamines.
• the deflocculating agent can be a mixture of compounds, such as a mixture comprising at least two compounds selected from: nonionic surfactant, anionic agent, polyacrylate, amine and organophosphorus compound.
• the deflocculating agent is preferably an organic deflocculating agent.
• an organic deflocculating agent comprises at least one carbon atom and preferably at least one carbon-oxygen bond.
• the organic deflocculating agent is selected from: a lignosulphonate (e.g. sodium lignosulphonate), a polyacrylate, a humate, a polycarboxylate such as an ether polycarboxylate, and mixtures thereof. More preferably, the deflocculating agent comprises a humate, a lignosulphonate and/or a polyacrylate.
• the deflocculating agent is preferably used in the form of a salt.
• the invention cannot be limited to the deflocculating agents mentioned above or their salts.
• the invention cannot be limited to the organic deflocculating agents mentioned above. Any type of organic deflocculating agent known to those skilled in the art can be used instead of said deflocculating agents mentioned above.
• the deflocculating agent can for example represent from 0% to 5% by dry weight of the binder for the concrete of a masonry unit. Indeed, in the context of a process according to the invention, there may be an absence of deflocculating agent.
• the deflocculating agent represents from 0.1% to 3% by dry weight of the construction binder. Even more preferably, the deflocculating agent represents from 0.2% to 1% by dry weight of the binder for masonry unit concrete.
• the deflocculating agent represents at least 0.1% by dry weight of the raw clay matrix, preferably at least 0.2% by dry weight of the raw clay matrix, more preferably at least 0 3% by dry weight of the raw clay matrix, even more preferably at least 0.4% by dry weight of the raw clay matrix, and for example at least 0.5% by dry weight of the raw clay matrix.
• the deflocculating agent represents at least 0.02% by dry weight, preferably at least 0.05% by dry weight, more preferably at least 0.07% in dry weight.
• the masonry unit, and preferably the compressed concrete block may include other additives such as glycerin, accelerating agents, air-entraining agents, foaming agents, wetting agents, or even shrinkage control agents.
• the compressed concrete block according to the invention comprises aggregates.
• the aggregates may correspond to natural aggregates, artificial aggregates or even recycled aggregates.
• the aggregates may also comprise mineral aggregates, that is to say mainly consisting of mineral matter and/or vegetable aggregates, that is to say mainly consisting of matter of vegetable origin.
• the aggregates may also include marine aggregates, i.e. mainly made up of organic or inorganic matter from the seabed such as siliceous aggregates and calcareous substances (e.g. ma ⁇ rl and shell sand).
• the mineral aggregates may for example correspond to sand, gravel, gravel, fillers (or fine materials), powders, fossilized waste and their combination.
• the compressed concrete block according to the invention when it comprises mineral aggregates, it preferably comprises at least 50% by weight of mineral aggregates, preferably at least 60% by weight of mineral aggregates, more preferably at least 70% by weight of mineral aggregates, and even more preferably at least 80% by weight of mineral aggregates.
• the compressed concrete block according to the invention will preferably comprise at most 95% by weight of mineral aggregates, more preferably at most 90% by weight of mineral aggregates.
• the compressed concrete block according to the invention may preferably comprise between 50% and 95% by weight of mineral aggregates and more preferably between 60% and 90% by weight of mineral aggregates.
• the plant aggregates may, for example, correspond to wood (chips or fibers), hemp, straw, hemp hemp, miscanthus, sunflower, cattail, corn, flax, bales of rice, wheat husks, rapeseed, seaweed, bamboo, cellulose wadding, fiber cloth and their combination.
• the compressed concrete block according to the invention when it comprises vegetable aggregates, it preferably comprises at least 10% by weight of aggregates plants, preferably at least 15% by weight of plant aggregates, more preferably at least 20% by weight of plant aggregates, and even more preferably at least 25% by weight of plant aggregates.
• the compressed concrete block according to the invention will preferably comprise at most 60% by weight of vegetable aggregates, and more preferably at most 50% by weight of vegetable aggregates.
• the compressed concrete block according to the invention may preferably comprise between 10% and 50% by weight of vegetable aggregates and more preferably between 15% and 35% by weight of vegetable aggregates.
• plant aggregates in the compressed concrete block according to the invention they may be combined with mineral aggregates such as sand. This can improve the mechanical performance.
• the compressed concrete blocks may have a water buffer value, measured no earlier than 10 days after manufacture, of at least 0.75; preferably by at least 1. So, such compressed concrete blocks make it possible to combine mechanical properties, compactability, low carbon footprint and water buffering capacity improving the summer comfort of homes. In addition, these materials have a remarkable aesthetic (see figures 2 and 3)
• the invention relates to a method for preparing masonry elements, in particular a method for preparing blocks of compressed concrete having a surface mass less than or equal to 600 kg/m 2 .
• a method for preparing masonry elements according to the invention can be implemented with devices or systems usually used for preparing compressed concrete blocks.
• a method 100 of preparation will comprise the following steps: mixing 110 a raw clay matrix, a composition of calcined metal oxides and aggregates and water; placing the mixture obtained 120 in moulds; applying 140 pressure to a surface of the molded mixture, preferably the top surface; remove 160 the pressed blocks from the moulds.
• the preparation process may include steps of vibration 130 of the molds to place the mixture in the mold and of vibration again 150 of the molds before removing the pressed blocks; and curing 170 concrete blocks compressed preferably obtained in a curing chamber.
• a preparation process 100 comprises a step 110 of mixing a raw clay matrix, a composition of calcined metal oxides, aggregates and water.
• the mixing step can be carried out in several sub-steps.
• the preparation process 100 may include a premix of a raw clay matrix and a calcined metal oxide composition.
• the method according to the invention may advantageously comprise the addition of an activating composition, preferably an alkaline activating composition. This premix can be hydrated so as to form a construction binder.
• the method according to the invention may comprise a mixture of a composition of calcined metal oxides and of a raw clay matrix so that a mass ratio of the composition of calcined metal oxides to the raw clay matrix is between 0.2 and 5, preferably 0.4 and 2.5 or 0.7 and 4, more preferably 0.8 and 3 or between 0.5 and 2.
• the process may include the addition of aggregates and possibly water.
• the mixture to be placed in the molds is weakly hydrated with a water to dry matter mass ratio of the composition preferably adjusted to a value between 0.3 and 0 .6 and more preferably between 0.3 and 0.45.
• a preparation method 100 according to the invention comprises a step aimed at placing 120 the mixture obtained in moulds.
• the molds will give shape to the compressed concrete block and form its cavities if necessary.
• the step aimed at placing the mixture obtained in the molds may be preceded by a step of extruding the mixture.
• a preparation method 100 according to the invention may at this time include a step aimed at vibrating 130 the molds so as to distribute the mixture in the molds.
• the step of vibration can be performed with the parameters usually used in the field, in particular, the vibration frequency can vary depending on the targeted properties.
• a method of preparation 100 according to the invention comprises a step aimed at applying 140 pressure to the molded mixture, for example on a surface of the molded mixture, preferably on the upper surface.
• the pressure may be exerted via conventional means of forming compressed concrete blocks.
• the fact of applying pressure to a surface does not exclude the possibility of applying pressure to several surfaces. Thus, these can for example apply the pressure on several surfaces of the molded mixture.
• the pressure exerted may typically correspond to a pressure at least equal to 50 kg/m 2 for at least 15 seconds.
• Compression can be carried out, for example, using a fixed concrete press.
• the press can be associated with a concrete plant equipped with probes for controlling the hydrometry of the materials in order to have a good control of the concrete consistencies.
• the production capacities may vary depending on the products, however the process according to the invention is advantageously configured so as to manufacture at least 15,000 blocks of compressed concrete over 12 hours.
• a manual or laying press may be used. It can for example be associated with a concrete production unit in line with the needs and capable of producing “controlled” concrete.
• a preparation process 100 may include a step aimed at making the molds vibrate again 150 before removing the compressed concrete blocks from the moulds. This step facilitates the removal of the moulds.
• the vibration step can be performed with the parameters usually used in the field.
• the method also includes a step aimed at removing 160 the compressed concrete blocks from the moulds.
• This step is preferably carried out immediately after having compressed the mixture or immediately after having vibrated the mold again.
• the step aimed at removing the compressed concrete blocks can be carried out less than 5 minutes, preferably less than 2 minutes, more preferably less than 1 minute, even more preferably less than 30 seconds after the step aiming to place 120 the mixture in the moulds.
• the building blocks advantageously have a surface mass less than or equal to 600 kg/m 2 .
• the method may then include a curing step 170 aimed at maturing the compressed concrete blocks obtained and possibly placing them in a curing chamber.
• Such a step allows time for the compressed concrete blocks to mature and allow an improvement in the mechanical, physicochemical and hygrometric properties of the blocks.
• this step also called the curing step, can allow an increase in the compressive strength of the blocks obtained.
• this curing stage can be less than 28 days, preferably less than 15 days, more preferably less than 10 days, even more preferably less than or equal to 7 days.
• the concrete blocks compressed according to the present invention have the advantage of reaching a plateau more quickly for their value of mechanical resistance in compression.
• the compressed concrete blocks according to the present invention in addition to a lower carbon footprint, have advantageous characteristics for the industrialization of their production and the reduction of the operational costs of preparation.
• the curing step may include a heat treatment carried out at a temperature above 25°C, more preferably above 30°C.
• the heat treatment which can be carried out within the framework of the curing step, is carried out at a temperature lower than 100°C, preferably lower than or equal to 80°C.
• the heat treatment is carried out at a temperature between 20°C and 90°C, preferably the heat treatment step is carried out at a temperature between 25°C and 80°C; even more preferably between 25°C and 65°C.
• the heat treatment can be carried out over the entire curing stage but also over a shorter period.
• the heat treatment is carried out over a period of less than 20 hours, more preferably less than 15 hours, and even more preferably less than 10 hours.
• the heat used for the curing step comes from the recovery of waste heat from other surrounding processes.
• the curing step may be carried out in water or even include storage in a humid environment (e.g. humidity greater than 80%; preferably greater than 85% relative humidity) or even include a or more stages of wetting the compressed concrete blocks.
• a humid environment e.g. humidity greater than 80%; preferably greater than 85% relative humidity
• Preparation of a mixture for a constructive element In all the examples presented below, the formulations according to the invention are prepared according to an identical protocol, namely that a dry premix is carried out between a raw clay matrix, a composition of calcined metal oxides, and aggregates in predetermined quantities, then, after a first mixing, water is added.
• the water to dry matter mass ratio of the composition is adjusted to a value of between 0.04 and 0.07.
• the binder for masonry unit concrete comprises 35% by weight of raw clay matrix, 65% by weight of calcined metal oxide composition; and the dry mix for masonry unit concrete comprises 90% by weight of aggregates and 10% by weight of binder. This mixture being supplemented with water for a mass ratio of water to dry matter of the binder adjusted to a value of 0.06.
• the mixture for constructive element thus formed is then placed in a mould, compressed, unmolded and then left to mature at room temperature, that is to say about 20 degrees Celsius for seven days.
• the mixture can be placed in a mould, compressed, unmolded and then left to mature.
• the mechanical strength of a masonry unit means its resistance to compression, such compression being measured according to standard NF EN 771-3+A1/CN and is expressed in Mega Pascal (MPa).
• Table 2 below presents, for different types of compressed concrete block, the properties obtained.
• Table 2 above illustrates that the compressed block according to the invention, while it does not contain Portland cement or clinker, makes it possible to achieve performance equivalent to products comprising clinker and having a carbon footprint high.
• Table 3 above illustrates the properties of 4 concrete blocks compressed according to the present invention as a function of the dry weight content of some of its constituents.
• the compressed block according to the invention while it does not comprise Portland cement or clinker, makes it possible to achieve performance equivalent to products comprising clinker and having a high carbon footprint.
• the presence of deflocculant can make it possible to reduce the friability of a compressed concrete block obtained according to the present invention.
• Table 4 above illustrates the properties of 4 concrete blocks compressed according to the present invention.
• the compressed blocks MTU-M1 and MTU-M2 which are made with a ground clay matrix have a much higher mechanical resistance to compression than the compressed blocks MTU-M3 and MTU-M4 which are made with an unground clay matrix presenting a D50 greater than 2 mm.
• the use of a crushed clay with a D50 of less than 500 pm can reduce the number of non-conformities of the blocks produced and homogenize intra and inter batch performance.
• the presence of a deflocculating agent makes it possible to reduce the friability of the compressed block when a ground clay matrix is used, whereas it has no significant effect when the clay matrix used is not crushed.
• the invention may be subject to numerous variants and applications other than those described above.
• the various structural and functional characteristics of each of the implementations described above should not be considered as combined and/or closely and/or inextricably linked to each other, but on the contrary as simple juxtapositions.
• the structural and/or functional characteristics of the different embodiments described above may be the subject, in whole or in part, of any different juxtaposition or any different combination.

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• 2021
  • 2021-07-21 FR FR2107891A patent/FR3125527B1/fr active Active
• 2022
  • 2022-07-21 WO PCT/EP2022/070571 patent/WO2023001996A1/fr active Application Filing
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