Method for producing an organic- or organic / mineral-based aggregate, organic- or organic / mineral-based aggregate and uses thereof

Abstract

The invention relates to a method for producing an aggregate, the method being characterised in that at least one organic or organic / mineral particulate starting aggregate material is mixed with water and at least one mineral binder that can be hardened in the presence of water and / or at least one system that can form a hardened mineral binder in an aqueous medium to obtain a material in the form of a wet powder that is extruded or compressed in order to intimately mix the binder and / or the system capable of forming the binder / starting particulate material / water and increase the intrinsic density and decrease the intrinsic porosity of the material, and to obtain, following the hardening of the one or more binders, a hardened, solid mass which is in the form of the aggregate in the desired size and / or in the desired shape, or is transformed into the aggregate in the desired size and / or in the desired shape by means of a cutting or crushing step immediately after the compression step or in a later step.

Description

Process for manufacturing an organic or organic / mineral based aggregate, organic or organic / mineral based aggregate and applications of these aggregates

[0001] The present invention relates to a method for manufacturing an organic or organic / mineral based aggregate, to an organic or organic / mineral based aggregate obtainable by this method, as well as to applications of these aggregates.

[0002] In the context of current challenges of saving resources and limiting waste, circular economy solutions have been widely acclaimed in the world of construction and public works, particularly to save new aggregates. Thus, currently, crushed concrete, incineration bottom ash or crystallized slag can be used as aggregates to replace natural aggregates extracted from quarries.

[0003] However, these methods of manufacturing aggregates are not sufficient to resolve the problems of overproduction of waste as well as the lack of aggregate-type resources.

[0004] It is the objective of the present invention to satisfy this need, the method proposed for this purpose consisting of choosing at least one basic organic or organic / mineral granular material having a large specific surface area or grinding at least one basic organic or organic / mineral granular material so that it reaches such a granulometry by increasing its specific surface area, adding at least one binder and water, pressurizing the assembly and shaping to form the desired aggregate.

[0005] The present invention therefore firstly relates to a method for manufacturing an aggregate, characterized in that at least one organic or organic / mineral particulate starting material for the aggregate is mixed with water and at least one mineral binder that can be hardened in the presence of water and / or at least one system capable of forming a hardened mineral binder in an aqueous medium, to obtain a material in the form of a wet powder that is compressed by extrusion or pressing to intimately mix the binder and / or system capable of forming the binder / particulate starting material / water and increase the intrinsic density and reduce the intrinsic porosity of the material, and to obtain, as a result of the hardening of the binder(s), a hardened, solid mass, which is in the form of the aggregate of the desired size and / or shape, or is transformed into the aggregate of the desired size and / or shape by cutting or crushing,immediately after compression or in a later step.,

[0006] The starting particulate organic material can be chosen from wood, paper, cardboard, plastics, plants such as flax, hemp, cellulose fiber, insulating materials such as wood wool, household waste, biogenic waste, bituminous waste and their mixtures.

[0007] The starting particulate organic / mineral material may be chosen from non-inert, non-hazardous waste such as construction waste and ordinary industrial waste, household waste or tertiary waste, as well as from the organic materials listed above mixed with at least one particulate mineral material chosen in particular from sands, such as silica sand and basalt sand; non-reactive clays; sediments, such as dredging sediments; glass; plaster; coal; crushed concrete; crushed aggregates; insulating materials such as glass wool and rock wool; quarry fines; industrial process fines; and mixtures thereof.

[0008] In particular, non-inert, non-hazardous waste may be mentioned, which constitute mixtures of organic / mineral materials to be used directly as starting materials in the process according to the present invention. In particular, building waste such as demolition or construction waste from a building, including wood, plastics, glass wool, metals, or ordinary industrial waste, household waste or tertiary waste may be mentioned.

[0009] As can be understood, the wastes that come from various sources represent direct mixtures of starting materials according to the invention, the proportions of which change depending on the source.

[0010] The starting particulate organic or organic / mineral material or the mixture of starting particulate mineral materials may have a particle size defined by: a D90 value less than or equal to 2 mm, preferably 1.5 mm, even more preferably 1.1 mm; a D10 value greater than or equal to 0.01 mm, preferably 0.02 mm, even more preferably 0.03 mm; and a D50 value greater than or equal to 0.1 mm, preferably 0.2 mm, even more preferably 0.35 mm, and less than or equal to 1.1 mm, preferably 0.8 mm,

[0011] said material or said mixture of materials having been subjected to grinding if necessary to obtain this granulometry.

[0012] By D90, D10, D50 it is meant that 90%, 10%, 50% respectively of the particles by mass must have their smallest projected surface area each time of the indicated dimension.

[0013] For the aggregate to have better properties, the mixture between the starting particulate material and the binder or binder-forming system must be optimal within the composite forming this aggregate, that is to say, the material-binder / binder-forming system contact surface must be as large as possible. However, if this surface is too large, the material absorbs too much water and / or binder and therefore the composite becomes weakened. The particular values ​​of D90, D10 and D50 indicated above are advantageous for such optimization.

[0014] The hardenable mineral binder(s) may be chosen from: hydraulically setting cementitious binders, such as NF EN 206 standardized cements, such as Portland cement CEM I and Portland cement CEM III; mixtures based on at least three components chosen from clinkers, metakaolins, gypsum, slags, limestone fillers, silica fume, ash, pozzolans and pozzolanic materials; and mixtures of at least one binder defined in (a) and at least one component of a mixture as defined in (b).

[0015] The system(s) capable of forming a hardened mineral binder in an aqueous medium may consist of: at least one precursor for the formation of a geopolymer or an activated alkali, chosen in particular from kaolins, metakaolins, shales, clays, slags, ashes and mixtures thereof, kaolins, shales and clays which may have undergone a heat treatment such as calcination or flash treatment; and at least one activator for the formation of an activated binder chosen from soda, potash and sodium and / or potassium silicates.

[0016] At least one shaping aid chosen in particular from: petro-sourced polymers, such as polyamides, such as polyacrylamides, and concrete plasticizers and superplasticizers; bio-sourced polymers, such as corn starch or cellulose ether; and mineral plasticizers, such as bentonite and non-reactive ash.

[0017] Particularly preferably, the mixture is obtained in the form of a wet powder from:50 to 95 parts by weight, in particular 65 to 90 parts by weight, of said particulate starting material(s); and5 to 50 parts by weight, in particular 10 to 35 parts by weight, of said binder(s) and / or binder-forming system(s),

[0018] water being added at a rate of 2 to 40 parts by weight and the shaping aid(s) being able to be added up to 5 parts by weight,

[0019] all these parts by weight being given for 100 parts by weight of (A) + (B).

[0020] Water helps to harden the binder by contributing to the hydraulic setting in the case of a hardenable mineral binder or by constituting the formation medium for the geopolymer or activated alkali. Furthermore, water can help with compression by fluidifying the mass to be compressed.

[0021] The quantities of the mixture can be advantageously adjusted before compression to obtain a wet powder rheology corresponding to a concrete of class S1 to S3 according to standard NF EN 12 350-2, in particular class S1 (slump between 10 and 40 mm at the Abrams cone).

[0022] Mixing can be carried out in a paddle, plowshare, ribbon or planetary mixer for a time ranging from 3 seconds to 3 minutes.

[0023] The wet powder is advantageously compressed by extrusion in a single-screw extruder or in a twin-screw extruder or by pressing using a piston press or a vibro-compaction press to directly obtain the desired granulate or to obtain a sausage which is then cut into the desired granulate or using a compression wheel which allows the desired granulate to be obtained directly.

[0024] Compression allows several phenomena: increase in the intrinsic density of the material; intimate mixing of the binder, the material and the water; reduction of the intrinsic porosity of the material; and creation of minimal cohesion before the end of the maturation phase.

[0025] Thus without compression, the composite cannot remain in the form of aggregate while maturation takes place and at best will be filled with porosity with unactivated binder and at worst will disintegrate before its complete setting.

[0026] Either after compression, or after shaping, or after compression and after shaping, maturation can advantageously be carried out, depending on the case, on the hardened product or the aggregate in a closed enclosure for a period of 1 hour to 10 days at a temperature of 15 to 70°C.

[0027] The present invention also relates to an aggregate obtained by the process as defined above, having at least one of: a water absorption according to standard NF EN 1097-6 of less than 37% by weight; a density according to standard NF EN 1097-6 of 1.4 to 3 g / cm 3 , preferably 1.6 to 2.5 g / cm 3 ; and a Los Angeles coefficient according to standard EN 1097-2 of less than 85, preferably from 10 to 70.

[0028] The aggregate as defined above advantageously has a particle size of 4 to 70 mm, preferably 4 to 31.5 mm.

[0029] The present invention also relates to the use of the aggregate manufactured by the process as defined above or of the aggregate as defined above, as aggregate for concrete (ready-mix concrete, prefabricated concrete, etc.), aggregate for asphalt, as backfill for geotechnical use, as road sub-base or as decorative aggregate, said granular material being used alone or in a mixture with other aggregates, for example with conventional aggregates such as natural aggregates, artificial aggregates or recycled aggregates based on crushed concrete in particular.

[0030] The following Examples illustrate the present invention without, however, limiting its scope.

[0031] In these examples, percentages and parts are given by weight unless otherwise indicated.

[0032] Example 1: Production of an aggregate based on construction waste and inert mineral materials

[0033] A mixture of construction waste composed of 30% organic materials based on wood, paper and cardboard and 70% of a mixture of inert materials based on ground concrete and plaster was ground to obtain a particle size defined by a D90 of 0.6 mm, a D10 of 0.04 mm and a D50 of 0.2 mm.

[0034] A mixture was then prepared in the form of a wet powder, having the following composition: Ground mixture thus obtained 64.2 parts Cement CEM III (binder) 35.8 parts Water 15 parts Superplasticizer Visco crete sika Dynamon NG (MBS) (forming aid) 0.5 parts

[0035] Then the mixture thus prepared was subjected to compression by passing it through a single-screw extruder, at the outlet of which the dehydrated bound mixture thus shaped in the form of a sausage was cut into a granule with a particle size of [10; 14] mm.

[0036] This aggregate was then subjected to maturation in a closed enclosure for 3 days at 20°C.

[0037] This aggregate had: a density of 1.8 g / cm 3 ;a water absorption of 20%; and a Los Angeles coefficient of 70.

[0038] Example 2: Production of an aggregate based on quarry fines and flax fibers

[0039] A mixture of 90% quarry fines and 10% flax fibers was ground to a particle size defined by a D90 of 1 mm, a D10 of 0.06 mm and a D50 of 0.2 mm.

[0040] A mixture was then prepared in the form of a wet powder, having the following composition: Ground mixture thus obtained: 75 parts Mixture of 59.5% clinker, 22.5% blast furnace slag and 18% limestone filler: 25 parts Water: 15 parts Superplasticizer Visco crete sika Dynamon NG (MBS) (forming aid): 1 part

[0041] The mixture was then subjected to compression in a piston extruder to obtain blocks of the dehydrated bound mixture thus shaped, which were subjected to maturation in a closed enclosure for 3 days at 25°C.

[0042] At the end of maturation, the blocks thus obtained were crushed to obtain aggregates with a grain size of [4-30 mm].

[0043] This aggregate had: a density of 1.6 g / cm 3 ;a water absorption of 20%; and a Los Angeles coefficient of 50.

[0044] Example 3: Production of an aggregate based on DIB

[0045] A mixture of construction waste composed of 30% organic materials based on wood, paper and cardboard and 70% of a mixture of inert materials based on ground concrete and plaster was ground to a particle size defined by a D90 of 0.7 mm, a D10 of 0.1 mm and a D50 of 0.25 mm.

[0046] A mixture was then prepared in the form of a wet powder, having the following composition:Ground mixture 54.2 partsCEM I cement 45.8 partsWater 25.4 partsBentonite (forming aid) 1.7 parts

[0047] Then the mixture thus prepared was subjected to compression by a compaction wheel and then to maturation at 45°C for 5 days to obtain an aggregate with a particle size of 10-14mm.

[0048] This aggregate had: a density of 1.6 g / cm 3 ;a water absorption of 25%; and a Los Angeles coefficient of 75.

Claims

– A method of manufacturing an aggregate, characterized in that at least one organic or organic / mineral particulate starting material for an aggregate is mixed with water and at least one mineral binder that can be hardened in the presence of water and / or at least one system capable of forming a hardened mineral binder in an aqueous medium, to obtain a material in the form of a wet powder that is compressed by extrusion or pressing to intimately mix the binder and / or system capable of forming the binder / particulate starting material / water and to increase the intrinsic density and reduce the intrinsic porosity of the material, and to obtain, as a result of the hardening of the binder(s), a hardened, solid mass, which is in the form of the aggregate of the desired size and / or shape, or is transformed into the aggregate of the desired size and / or shape by cutting or crushing,immediately after compression or in a later step., – Method according to claim 1, characterized in that the starting particulate organic material is chosen from wood, paper, cardboard, plastics, plants such as flax fiber, hemp fiber, cellulose fiber, insulating materials such as wood wool, household waste, biogenic waste, bituminous waste and mixtures thereof, and the starting particulate organic / mineral material is chosen from non-inert non-hazardous waste such as construction waste and ordinary industrial waste, household waste or tertiary waste, as well as from the organic materials listed above in a mixture with at least one particulate mineral material chosen in particular from sands, such as silica sand and basalt sand; non-reactive clays; sediments, such as dredging sediments; glass; plaster; coal; crushed concrete; crushed aggregates;insulating materials such as glass wool and rock wool; quarry fines; industrial process fines; and their mixtures.; – Method according to one of claims 1 and 2 characterized in that the starting particulate organic or organic / mineral material or the mixture of starting particulate mineral materials have a particle size defined by: a D90 value less than or equal to 2 mm, preferably 1.5 mm, even more preferably 1.1 mm; a D10 value greater than or equal to 0.01 mm, preferably 0.02 mm, even more preferably 0.03 mm; and a D50 value greater than or equal to 0.1 mm, preferably 0.2 mm, even more preferably 0.35 mm, and less than or equal to 1.1 mm, preferably 0.8 mm, said material or said mixture of materials having been subjected to grinding if necessary to obtain this particle size. – Method according to one of claims 1 to 3, characterized in that the hardenable mineral binder(s) are chosen from: hydraulically setting cement binders, such as NF EN 206 standardized cements, such as Portland cement CEM I and Portland cement CEM III; mixtures based on at least three components chosen from clinkers, metakaolins, gypsum, slags, limestone fillers, silica fume, ash, pozzolans and pozzolanic materials; mixtures of at least one binder defined in (a) and at least one component of a mixture as defined in (b). – Method according to one of claims 1 to 4, characterized in that the system(s) capable of forming a hardened mineral binder in an aqueous medium are constituted by: at least one precursor for the formation of a geopolymer or an activated alkali, chosen in particular from kaolins, metakaolins, shales, clays, slags, ashes and their mixtures, kaolins, shales and clays which may have undergone a heat treatment such as calcination or flash treatment; and at least one activator for the formation of an activated binder chosen from soda, potash and sodium and / or potassium silicates. – Method according to one of claims 1 to 5, characterized in that at least one shaping aid chosen in particular from: petro-sourced polymers, such as polyamides, such as polyacrylamides, and concrete plasticizers and superplasticizers; bio-sourced polymers, such as corn starch or cellulose ether; and mineral plasticizers, such as bentonite and non-reactive ash. - Method according to one of claims 1 to 6, characterized in that the mixture is obtained in the form of a wet powder from:50 to 95 parts by weight, in particular 65 to 90 parts by weight, of said particulate starting material(s); and5 to 50 parts by weight, in particular 10 to 35 parts by weight, of said binder(s) and / or binder-forming system(s),water being added in an amount of 2 to 40 parts by weight and the shaping aid(s) being able to be added up to 5 parts by weight,all these parts by weight being given per 100 parts by weight of (A) + (B). - Method according to one of claims 1 to 7, characterized in that the compression of the wet powder is carried out by extrusion in a single-screw extruder or in a twin-screw extruder or by pressing using a piston press or a vibro-compaction press to directly obtain the desired granulate or to obtain a sausage which is then cut into the desired granulate or using a compression wheel which makes it possible to directly obtain the desired granulate. - Method according to one of claims 1 to 8, characterized in that, either after compression, or after shaping, or after compression and after shaping, maturation is carried out, depending on the case, of the hardened product or of the granulate in a closed enclosure for a period of 1 hour to 10 days at a temperature of 15 to 70°C. – Aggregate obtained by the process as defined in one of claims 1 to 9, having at least one of: a water absorption according to standard NF EN 1097-6 of less than 37% by weight; a density according to standard NF EN 1097-6 of 1.4 to 3 g / cm 3 , preferably 1.6 to 2.5 g / cm 3 ; and a Los Angeles coefficient according to standard EN 1097-2 of less than 85, preferably from 10 to 70. – Aggregate according to claim 10, characterized in that it has a particle size of 4 to 70 mm, preferably 4 to 31.5 mm. - Use of the aggregate manufactured by the method according to one of claims 1 to 9 or as defined in one of claims 10 and 11, as aggregate for concrete, aggregate for asphalt, as backfill for geotechnical use, as road sub-base or as decorative aggregate, said granular material being used alone or in a mixture with other aggregates.