WO2020249145A1 - Mélange sec pour la préparation de béton, béton frais et procédé de préparation de béton frais - Google Patents

Mélange sec pour la préparation de béton, béton frais et procédé de préparation de béton frais Download PDF

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Publication number
WO2020249145A1
WO2020249145A1 PCT/CZ2020/050046 CZ2020050046W WO2020249145A1 WO 2020249145 A1 WO2020249145 A1 WO 2020249145A1 CZ 2020050046 W CZ2020050046 W CZ 2020050046W WO 2020249145 A1 WO2020249145 A1 WO 2020249145A1
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WO
WIPO (PCT)
Prior art keywords
aggregate
substituent
recyclate
concrete
seconds
Prior art date
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PCT/CZ2020/050046
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English (en)
Inventor
Frantisek POLAK
Lucie SLAVICKOVA
Jiri Fiala
Jan Cermak
Pavel GORECKY
Original Assignee
ERC-TECH a.s.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from CZ2019375A external-priority patent/CZ308833B6/cs
Application filed by ERC-TECH a.s. filed Critical ERC-TECH a.s.
Publication of WO2020249145A1 publication Critical patent/WO2020249145A1/fr

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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
    • C04B28/02—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
    • C04B28/04—Portland 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
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/20—Resistance against chemical, physical or biological attack
    • C04B2111/28—Fire resistance, i.e. materials resistant to accidental fires or high temperatures
    • 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
    • C04B2111/52—Sound-insulating materials
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

  • the invention relates to a method for preparing fresh concrete using recyclate from inert construction and demolition waste.
  • the invention also relates to fresh concrete prepared by this method.
  • the invention further relates to a dry mixture for preparation of this concrete.
  • Crushed or ground inert construction and demolition waste is used mainly for packs and backfills of utility lines (a substitute for sorted gravel), as a sub-base for parking lots, roads, concrete structures of floors of buildings and halls, backfills of forefields of bridges, for the consolidation and levelling of forest and field roads (a substitute for a crusher-run materials), or as a sub-base filler of ground bodies of driveways and roads, trackbeds, flood protection barriers (as a substitute for soil), etc.
  • utility lines a substitute for sorted gravel
  • roads concrete structures of floors of buildings and halls
  • backfills of forefields of bridges for the consolidation and levelling of forest and field roads (a substitute for a crusher-run materials)
  • the object of the invention is to provide fresh concrete in which the largest possible part of the aggregate is made up of recycled material produced by grinding or crushing inert construction and demolition waste.
  • the method for the preparation of concrete according to the invention is based on a combination of a specific composition of the concrete and a specific procedure of mixing and dosing its components, which in mutual combination allow to replace up to 100 % by weight of the aggregate in the concrete with recyclate made from inert construction and demolition waste (i.e. ground or crushed inert construction and demolition waste) while achieving mechanical and physical parameters which are at least comparable to or even better than, conventional concretes.
  • inert construction and demolition waste i.e. ground or crushed inert construction and demolition waste
  • the fresh concrete thus prepared contains in 1 m 3 160 to 500 kg of water, 135 to 580 kg of cement or 135 to 600 kg of a mixture of cement and at least one substituent thereof, 5 to 65 kg of microsilica (preferably compacted) or at least one substituent thereof or a mixture of microsilica and at least one substituent thereof, 1000 to 2300 kg of aggregate, whereby 30 to 100 % by weight of the aggregate is formed by recyclate made from inert construction and demolition waste, 0 to 45 % by weight of the aggregate consists of natural aggregate and another 0 to 45 % by weight of the aggregate consists of lightweight artificial aggregate (such as agloporite, ceramsite, expandit, expanded perlite, etc.) and/or cinder and/or scoria and/or polystyrene and/or at least one organic filler (such as wood sawdust, shavings, rice husks, shives, etc.) and/or another component for improving thermal and/or acoustic and/or fire resistance properties
  • the fresh concrete contains in 1 m 3 50 to 300 kg of water, 135 to 400 kg of cement or 135 to 600 kg of a mixture of cement and at least one substituent thereof, 10 to 27,9 kg of microsilica (preferably compacted) or at least one substituent thereof or a mixture of microsilica and at least one substituent thereof, 1000 to 2300 kg of aggregate, whereby 30 to 100 % by weight of the aggregate is formed by brick or ceramic or mixed recyclate made from inert construction and demolition waste, 0 to 40 % by weight of the aggregate consists of natural aggregate and another 0 to 40 % by weight of the aggregate consists of lightweight artificial aggregate (such as agloporite, ceramsite, expandit, expanded perlite, etc.) and/or cinder and/or scoria and/or polystyrene and/or at least one organic filler (such as wood sawdust, shavings, rice husks, shives, etc.) and/or another component for improving thermal and/or acou
  • Fresh concrete optimized for 3D printing technology contains in 1 m 3 160 to 500 kg of water, 135 to 580 kg of cement or 135 to 600 kg of a mixture of cement and at least one substituent thereof, 5 to 65 kg of microsilica (preferably compacted) or at least one substituent thereof or a mixture of microsilica and at least one substituent thereof, 1000 to 1650 kg of aggregate, whereby at least 55 % by weight of the aggregate is formed by recyclate made from inert construction and demolition waste.
  • the used recyclate from inert construction waste can have substantially any fraction depending on the use of the concrete and requirements for its texture - it may be, for example, one-fractional, preferably having a fraction of 0 to 20 mm, two-fractional, preferably having fractions of 0 to 8 mm and 8 to 20 mm, or three-fractional, preferably having fractions of 0 to 4 mm, 4 to 8 mm and 8 to 20 mm.
  • recyclate and aggregate with a fraction of up to 16 mm or up to 8 mm can be used.
  • the upper fraction of the whole aggregate in the concrete optimized for 3D printing technology is up to 8 mm, preferably up to 4 mm.
  • brick recyclate a recycled material produced by crushing or milling inert construction and demolition waste (incl. construction residues and/or waste from the industrial production of construction products), which consists entirely or of at least a majority of bricks and possibly contains other building materials and/or substances (concrete, ceramic building elements and fittings, mortar, plaster and adhesive residues, etc.).
  • brick recyclate consists entirely or of at least of a majority of crushed brick, possibly with the addition of rubble from other building materials and/or substances.
  • ceramic recyclate we understand a recycled material produced by crushing or milling inert construction and demolition waste (incl. construction residues and/or waste from the industrial production of construction products), which consists entirely or of at least a majority of ceramic building and fitting elements, such as floor and wall tiles, sanitary ceramic products, clay roofing tiles, etc., and possibly contains other building materials and/or substances (concrete, bricks, mortar, plaster and adhesive residues, etc.).
  • ceramic recyclate consists entirely or of at least a majority of crushed ceramics, possibly with the addition of rubble from other building materials and/or substances.
  • concrete recyclate we understand a recycled material produced by crushing or milling inert construction and demolition waste (incl. construction residues and/or waste from the industrial production of construction products), which consists entirely or of at least a majority of concrete or another cement containing material (concrete screed, cement mortar, etc.), and possibly with admixtures of other building materials and/or substances (bricks, ceramic building and fitting objects, mortar, plaster and adhesive residues, etc.).
  • concrete recyclate consists entirely or of at least a majority of crushed concrete or other cement containing materials, possibly with the addition of rubble from other building materials and/or substances.
  • mixed recyclate a recycled material produced by crushing or milling mixed inert construction and demolition waste (incl. construction residues and/or waste from the industrial production of construction products), which is composed of a mixture of different building materials and substances, usually bricks, concrete and ceramic building elements and fittings in various ratios, possibly with admixtures of mortar, plaster and adhesive residues, etc., or recyclate produced by mixing two or more above-mentioned recyclates (brick, ceramic, concrete)
  • mixed recyclate is composed of mixed rubble made from construction and demolition waste.
  • microsilica we understand an anti-corrosion powder additive for concretes and mortars based on amorphous S1O2 with a micro filling, pozzolanic and rheological effect.
  • the usual grain size of microsilica is 100 % ⁇ 100 pm, its specific surface area being 20 to 22 m 2 /g.
  • Microsilica can be supplemented or replaced by at least one of its known substituents, such as metakaolin, shale, ground-granulated blast furnace slag (GGBS or GGBFS), fly ash, micronized limestone, etc.
  • GGBS or GGBFS ground-granulated blast furnace slag
  • fly ash micronized limestone
  • fresh concrete with a finer texture is prepared, sometimes referred to as cement mortar or concrete mortar.
  • the fresh concrete according to the invention may contain in any variant at least one additive for concrete in a total amount of up to 10 % by weight of a dose of cement or of a dose of cement and substituent(s) thereof.
  • any known additive can be used, for example additive for vibro-pressed concrete and/or additives according to EN 934-2.
  • additives include especially water- reducing (plasticizing) and strongly water-reducing (superplasticizing or hyperplasticizing) additives, additives for improving the consistency of concrete, water- reducing additives, additives for improving the strength and some other properties of fresh and hardened concrete, as well as stabilizing additives, air-entraining admixtures, foaming agents, additives accelerating hardening and solidification of concrete, additives for retarding hardening and solidification of concrete, sealing agents, corrosion inhibiting additives, etc.
  • This additive/these additives is/are added to the other components of concrete dissolved in mixing water or separately, preferably after the addition of the mixing water.
  • the total amount of all water-reducing additives is preferably up to 10 kg/m 3 of fresh concrete
  • the total amount of all stabilizing additives is preferably up to 2 kg/m 3 of fresh concrete
  • the total amount of all accelerating additives is preferably up to 50 kg/m 3 of fresh concrete, etc.
  • any industrial mixers can be used, for example planetary mixers, rotor mixers, single shaft mixers, dual shaft mixers or triple shaft mixers, trough mixers, continuous mixers, etc.
  • a mixer with a forced circulation is especially advantageous, preferably a mixer with radial movement of mixing arms or with double simultaneous radial movement of mixing arms (such as the mixer described in IT 1244970 or in EP 0508962), in which all its interior surfaces are wiped. Nevertheless, it is necessary to observe not only the above-mentioned concrete composition, but also the mixing and dosing times of the individual components. All the components are dosed while the mixer is running.
  • recyclate made from inert construction and demolition waste is hygienized, e.g. by water or steam bath or otherwise, thereby reducing the number of (pathogenic) organisms and microorganisms present in it or completely eliminating the presence of these organisms and microorganisms.
  • Microsilica and/or substituent(s) thereof which serves as a binder in the conventional production of conventional concretes from natural aggregates, serves as a filler in the preparation of concrete according to the invention, provided that the below-described dosing method and the above-described mixing method is observed, filling the overall lattice structure of the concrete, together with the pozzolanic powder produced by rubbing the grains of the recyclate from construction and demolition waste, covering the particles of the recyclate and filling up intensively the pores therein. Thanks to that, there is no clustering of fine particles and the resulting concrete has a lower porosity and after hardening achieves mechanical and physical parameters comparable to conventional concretes.
  • compacted microsilica having a smaller volume is used.
  • microsilica may be replaced by at least one microsilica substituent, such as metakaolin or shale with a silica content of at least 45 %.
  • a mixture of microsilica and substituent(s) thereof containing 30 % to 70 % by weight of microsilica is used.
  • microsilica and/or substituent(s) thereof is added to the mixer only after the last part of the aggregate.
  • FIG. 1 shows a SEM image of a grain of the recyclate from inert construction and demolition waste with microparticles of microsilica deposited on its surface and in its pores at a magnification of 1000 times
  • Fig. 2 which shows a SEM image of the surface of the recyclate grain with the emerging transit zone, where it is possible to see also the resulting Ca(OH) - portlandite, produced by the reaction of CaO contained in the aggregate and free water, at a magnification of 10,000 times
  • Fig. 3 shows a SEM image of the surface of the recyclate grain of Fig. 2 at 20,000 times magnification.
  • Part of the dose of cement may be replaced with a substituent of cement, e.g., with ground-granulated blast-furnace slag - GGBS or GGBFS and/or with fly ash, ground-calcium carbonate - GCC, stone powder (dust from aggregate mining and processing), or, optionally, with a mixture of at least two such substituents, whereby the ratio of cement to substituents of cement in the fresh concrete is from 30:70 to 70:30.
  • This means that the total amount of cement and substituents of cement is the same as the amount of the cement alone, i.e. 135 to 400 kg/m 3 of fresh concrete, or up to 600 kg/m 3 of fresh concrete.
  • cement and the substituent(s) of cement are added to the mixture at the same time, separately, or successively in any order (adding substituent(s) of cement first and then cement is preferred, but is not necessary), or in the form of a pre- formed mixture of the above-described composition.
  • this mixture After the preparation of the dry mixture from the above-mentioned components and after thorough mixing, this mixture is sprinkled with mixing water in a mixer under constant mixing, or the mixing water is sprayed on it.
  • this method of dosing the mixing water the surface of the cement is gradually moistured and the cementing paste being formed gradually adheres to the grains of the recyclate already covered with a mixture of microsilica and pozzolanic powder, which prevents the agglomeration of fresh concrete particles, separation of the fine particles of the mixture as well as separation of water and ensures the required consistency of the fresh concrete.
  • this dosing method activates the silica present in the microsilica and/or substituent(s) thereof and in pozzolanic powder and thereby latent hydraulicity of these components, which allows the concretes prepared by this method to achieve physical and mechanical parameters comparable to conventional concretes, this being achieved even at a dose of cement which may be lower than that for conventional concretes. Due to the unexpectedly large amount of pozzolanic powder, it is possible to shorten the mixing times compared to other processes and significantly reduce the required amount of microsilica and/or substituent(s) thereof.
  • the mixing water quality must correspond to the drinking water. If required, it may contain at least one known standard additive (dissolved or undissolved) for concrete.
  • the friction of the aggregate grains intensively rubs the grains of the recyclate from the inert construction and demolition waste and consequently increases the specific surface area of the recyclate and creates a fine pozzolanic powder, whereby the microsilica and/or substituent(s) thereof, together with the pozzolanic powder, cover/covers the aggregate particles and fill the pores in them.
  • 135 to 400 kg of cement are added to the mixture thus obtained, under constant mixing within 1 to 20 seconds, preferably within 1 to 9.9 seconds, or cement and at least one substituent thereof in a total amount of 135 to 600 kg is added to it sequentially in any order or at the same time, under constant mixing within 1 to 20 seconds, and the mixture thus formed is mixed for a further 5 to 39.9 seconds, whereupon the mixture is sprinkled with 50 to 300 kg of mixing water under constant mixing within 5 to 39.9 seconds, or this amount of mixing water is sprayed onto it within 5 to 39.9 seconds, whereby the surface of the cement and, optionally, of its substituent(s) is gradually moistened and the paste formed gradually adheres onto the particles of the aggregate already covered with a mixture of microsilica and/or substituent(s) thereof and pozzolanic powder, and after a further 5 to 160 seconds of mixing, fresh concrete is prepared.
  • Fresh concrete optimized for 3D printing technology contains water, cement (possibly combined with at least one substituent thereof), microsilica or at least one substituent thereof, or a mixture of microsilica and at least one substituent thereof, and aggregate having an upper fraction up to 8 mm, preferably up to 4 mm, whereby at least 55 % by weight of the aggregate is composed of recyclate made from inert construction and demolition waste (i.e. crushed or ground inert construction and demolition waste).
  • Up to 45 % by weight of the aggregate of the concrete may be, if required, composed of natural aggregate and/or of at least one component for improving thermal and/or acoustic and/or fire resistance properties of hardened concrete which is commonly used for conventional concretes.
  • Such a component is, for example, light artificial aggregate (such as agloporite, ceramsite, expandit, expanded perlite, etc.) and/or cinder and/or scoria and/or polystyrene and/or at least one organic filler (such as wood sawdust, shavings, rice husks, shives and the like) etc.
  • light artificial aggregate such as agloporite, ceramsite, expandit, expanded perlite, etc.
  • cinder and/or scoria and/or polystyrene and/or at least one organic filler such as wood sawdust, shavings, rice husks, shives and the like
  • inert construction and demolition waste is a commonly available material with a very low price and when used in specific procedure of mixing (see, for example, CZ patent 307741 or CZ patent application 2018-141 ) it may replace up to 100 % of the aggregate in the concrete without affecting the mechanical properties of the concrete, its use significantly reduces the price of fresh concrete. In addition, this approach also reduces the environmental burden associated with the production of concrete and allows utilization of material that is currently almost useless and accumulates in landfills.
  • Recyclate made from inert construction and demolition waste consists of crushed or ground brick or ceramic or mixed or concrete recyclate (see above).
  • microsilica and/or at least one substituent thereof and pozzolanic powder produced by rubbing the grains of the recyclate from construction and demolition waste, cover the particles of the aggregate, particularly of the recyclate and fill the pores in them. This results in transfer of part of the transit zone into the pores of the grains of aggregate, particularly of the recyclate, which are thus strengthened and their mechanical properties are enhanced. At the same time, there is no clustering of fine particles and the resulting concrete has a lower porosity and, after hardening, it reaches physical and mechanical parameters comparable to conventional concretes.
  • Cement paste formed by moistening cement or substituent(s) thereof covers the aggregate particles already covered by a mixture of microsilica and/or at least one substituent thereof and pozzolanic powder.
  • fresh concrete may contain addition of finely ground recyclate from inert construction and demolition waste (brick, ceramic, mixed or concrete) having a particle size of 5 to 250 pm, preferably 5 to 125 pm (it may contain some technological proportion of larger particles) and having a specific surface of 300 to 1500 m 2 /kg.
  • This finely ground recyclate imparts compactness, desired consistency and the initial load-bearing capacity to the concrete according to the invention - the concrete remains unchanged after being laid out by the 3D printer and has sufficient load-bearing capacity for laying further layers.
  • this finely ground recyclate together with microsilica and/or at least one substituent thereof and pozzolanic powder produced by rubbing the grains of the recyclate in the aggregate cover the aggregate grains, especially the recyclate grains, and fill the pores in them.
  • part of the transit zone is moved to the pores of the aggregate grains, especially the recyclate grains, which are consequently strengthened and their mechanical properties are improved.
  • cement paste formed by moistening cement and, optionally, also substituent(s) thereof covers the aggregate particles already covered with a mixture of microsilica and/or at least one substituent thereof, pozzolanic powder and finely ground recyclate.
  • Pozzolanic powder produced by rubbing the grains of the recyclate in the aggregate during mixing has an uneven specific surface, different particle size and, as a result, a lower pozzolanic activity than the finely ground recyclate from inert construction and demolition waste.
  • a higher pozzolanic activity it is necessary for the S1O 2 molecules to be more accessible to calcium hydroxide, and so it is advisable for the recyclate to be ground to a higher specific surface and for most of its particles to have approximately the same size.
  • At least part of the pozzolanic powder which is produced when the grains in the recyclate are rubbed in the aggregate may be identical to the finely ground recyclate.
  • any excess of finely ground recyclate, preferably concrete recyclate, after covering the aggregate grains, especially the recyclate grains, and filling their pores, can, in the later stages of concrete preparation, due to its pozzolanic properties, serve as a substitute for a part of the dose of cement or supplement of cement and is incorporated in the cement paste which is formed by moistening cement and, optionally, also substituent(s) thereof, (the minimum amount of finely ground recyclate needed to cover the aggregate grains, especially the recyclate grains, and to fill their pores is approx. 10 kg / m 3 of concrete).
  • Fresh concrete optimized for 3D printing technology contains in 1 m 3 160 to 500 kg of water, 160 to 580 kg of cement or 160 to 600 kg of a mixture of cement and at least one substituent thereof, 5 to
  • microsilica or at least one substituent thereof or a mixture of microsilica and at least one substituent thereof and 1000 to 1650 kg of aggregate with an upper fraction up to 8 mm, preferably up to 4 mm, from which at least 55 % by weight is composed of recyclate from inert construction and demolition waste.
  • the individual aggregate grains, especially recyclate grains are covered and their pores are filled with a mixture of microsilica and/or at least one substituent thereof and pozzolanic powder, which is produced by the rubbing of the recyclate grains in the aggregate.
  • fresh concrete according to the invention may in any variant contain at least one additive or a combination of two or more additives for concrete in a dose of up to 10 % by weight of the cement dose, or of the dose of cement and its substituent(s).
  • Such an additive can be any known additive, for example, an additive for vibro-pressed concrete and/or an additive according to EN 934-2.
  • additives include especially water- reducing (plasticizing) and strongly water-reducing (superplasticizing) additives for improving the consistency of concrete, additives to reduce the dose of water, additives for improving the strength and some other properties of fresh and hardened concrete, as well as stabilizing additives, air-entraining admixtures, additives accelerating hardening and solidification of concrete, additives for retarding hardening and solidification of concrete, sealing agents, etc.
  • This additive/these additives is/are added dissolved in mixing water to the other components of concrete or separately, preferably after the addition of the mixing water.
  • the total amount of all water- reducing additives for concrete in the concrete according to the invention is preferably up to 10 kg/m 3 of fresh concrete
  • the total amount of all stabilizing additives for concrete in the concrete according to the invention is preferably up to 2 kg/m 3 of fresh concrete
  • the total amount of all accelerating additives for concrete in the concrete according to the invention is preferably up to 50 kg/m 3 of fresh concrete etc.
  • the fresh concrete according to the invention may further comprise reinforcing fibers which reinforce its structure and thus improve some of its properties, e.g. tensile strength and flexural tensile strength.
  • Suitable reinforcing fibers are, e.g., polypropylene (PP) fibers, polyvinyl alcohol (PVA) fibers, blends of polypropylene and polyethylene (PLV) fibers, cellulose fibers, steel fibers, glass fibers, carbon fibers, Kevlar fibers, etc. These fibers are typically added to the concrete mixture in an amount of up to 2 kg/m 3 of fresh concrete, in the case of steel and similar fibers the total amount is up to 110 kg/m 3 of fresh concrete.
  • aggregates consisting of at least 55 % by weight of recyclate from inert construction and demolition waste are mixed with microsilica and/or at least one substituent thereof in an industrial mixer for 5 to 80 seconds, preferably for 5 to 40 seconds.
  • the recyclate grains are rubbed in the aggregate, they are intensively abraded and, as a result, the specific surface of this recyclate is increased and fine pozzolanic powder is produced, whereby a mixture of microsilica and/or at least one substituent thereof and this pozzolanic powder covers the aggregate particles of, especially the recyclate particles, and fills the pores in them.
  • cement or cement and at least one substituent thereof one by one in any order or simultaneously is/are added to the thus obtained mixture under constant mixing within 1 to 20 seconds, preferably within 1 to 9.9 seconds, and the mixture thus obtained is mixed for a further 5 to 80 seconds, preferably for 5 to 40 seconds.
  • this mixture is sprinkled with the entire dose of mixing water under constant mixing within 5 to 60 seconds, preferably within 5 to 40 seconds, or it is sprayed with the entire dose of the mixing water within this time period, whereby the surface of cement and, optionally, also the surface of substituent(s) thereof is gradually moistened and the resulting cement paste gradually adheres to the aggregate particles already covered by a mixture of microsilica and/or substituent(s) thereof and pozzolanic powder.
  • fresh concrete is prepared.
  • the aggregate alone is mixed in an industrial mixer for 5 to 80 seconds, preferably for 5 to 40 seconds, after thorough mixing, microsilica and/or at least one substituent thereof is added to it under constant mixing within 1 to 15 seconds, preferably within 1 to 10 seconds, and the mixture thus obtained is mixed for a further 5 to 80 seconds, preferably 5 to 40 seconds.
  • the next procedure corresponds to the above.
  • the concrete also contains finely ground recyclate from internal construction and demolition waste
  • at least part of the dose of this recyclate is added to the mixer before cement - e.g. together with the aggregate (or one of its components) and/or microsilica and/or substituent(s) thereof.
  • the finely ground recyclate from internal construction and demolition waste is added to the mixed mixture separately, it is added to it within 1 to 15 seconds, preferably within 1 to 10 seconds, and the mixture obtained is mixed for another 5 to 80 seconds, preferably 5 to 40 seconds.
  • Any industrial mixer is used for thorough mixing of the individual components and the preparation of concretes (or dry mixtures) of the required structure and properties, preferably a mixer with a forced circulation, e.g., a mixer with radial movement of mixing arms or with double simultaneous radial movement of mixing arms (such as the mixer described in IT 1244970 or in EP 0508962), in which all its interior surfaces are wiped.
  • a mixer with a forced circulation e.g., a mixer with radial movement of mixing arms or with double simultaneous radial movement of mixing arms (such as the mixer described in IT 1244970 or in EP 0508962), in which all its interior surfaces are wiped.
  • any other type of industrial mixer can be used, including continuous mixers (when using a pre- prepared dry mixture).
  • cement possibly in combination with at least one substituent, is supplied only after the mixing of (most) aggregate with microsilica and/or or substituent(s) thereof (and optionally finely ground recyclate from inert construction and demolition waste).
  • all the components are dosed while the mixer is running.
  • mixing we also understand methods of mixing in which the running of the mixer is temporarily stopped after mixing the already inserted components and before adding the next component, or if the running of the mixer, if its construction allows, is reversed to insert some other component and mix it with the other components.
  • All the variants use cement of strength class CEM I to CEM V with binding capacity 32.5 N, R, 42.5 N, R, 52.5 N, R.
  • Part of the cement dose may be replaced by any known substituent of cement, such as ground-granulated blast-furnace slag (GGBS or GGBFS) and/or fly ash and/or ground calcium carbonate (GCC) etc., optionally by a combination of at least two such substituents, whereby the ratio of cement to the substituent(s) in fresh concrete is from 30:70 to 70:30.
  • the total amount of cement and substituents of cement is the same as the amount of the cement alone, i.e. 160 to 580 kg/m 3 of fresh concrete, optionally up to 600 kg/m 3 of fresh concrete.
  • Cement and the substituent(s) of cement are added to the mixture either at the same time or separately or successively in any order (preferably, but not necessarily, the substituent(s) of cement is/are added first and cement is added afterwards,), or in the form of a pre-formed mixture of the above-described composition. Due to its excellent pozzolanic properties, excess finely ground recyclate from inert construction and demolition waste, especially concrete recyclate, can also serve as a substituent of cement.
  • the mixing water must correspond to the quality of drinking water. If necessary, it may contain at least one known standard concrete additive (dissolved or undissolved).
  • This dry mixture then contains, per 1 m 3 of fresh concrete, 5 to 65 kg of microsilica or at least one substituent thereof or a mixture of microsilica and at least one substituent thereof and 1000 to 1650 kg of aggregate with an upper fraction up to 8 mm, preferably up to 4 mm, whereby at least 55 % by weight of the aggregate consists of recyclate from inert construction and demolition waste and the recyclate grains in the agregate are covered and their pores are filled with a mixture of microsilica and/or at least one substituent thereof and fine pozzolanic powder, which is produced by the rubbing of the recyclate grains in the aggregate.
  • the dry mixture for the preparation of fresh concrete according to the invention contains up to 375 kg of finely ground recyclate from inert construction and demolition waste having a particle size of 5 to 250 pm, or 5 to 125 pm, and a specific surface of 300 to 1500 m 2 /kg, whereby the aggregate grains, especially recyclate grains, are covered and their pores are filled with a mixture of this finely ground recyclate from inert construction and demolition waste, fine pozzolanic powder, which is produced during the mixing of the aggreagate and microsilica and/or at least one substituent thereof.
  • the dry mixture may further contain per 1 m 3 of fresh concrete 160 to 580 kg of cement, or cement and at least one substituent thereof in a total amount of 160 to 580 kg or up to 600 kg (wherein the ratio of cement to cement substituent(s) is 30:70 to 70:30).
  • any known type of mixer including a continuous mixer, can be used.
  • Fig. 1 is a SEM image of a grain of recyclate made from inert construction and demolition waste in the structure of fresh concrete produced by the method according to the invention at a magnification of 1 ,000 times
  • Fig. 2 is a SEM image of a grain of recyclate made from inert construction and demolition waste in the structure of fresh concrete produced by the method according to the invention at a magnification of 10,000 times
  • Fig. 3 is a SEM image of the grain of recyclate made from inert construction and demolition waste in the structure of fresh concrete produced by the method according to the invention at a magnification of 20,000 times.
  • examples 1 and 2 Exemplary variants of the preparation of fresh concrete according to the invention are described below, the first of which for the case when 100 % by weight of the aggregate is formed by one type of recyclate made from inert construction and demolition waste (examples 1 and 2), the second variant for the case when the aggregate is formed by recyclate from inert construction and demolition waste in combination with concrete recyclate or with natural aggregate (up to 40 % by weight of the total aggregate) (examples 3 and 4), the third variant for the case when 100 % by weight of the aggregate is formed by a combination of two types of recyclate from inert construction and demolition waste (examples 5 and 6), the fourth variant for the case when the aggregate is formed by a combination of three types of recyclate from inert construction and demolition waste or by a combination of two types of recyclate from inert construction and demolition waste and natural aggregate (up to 40 % by weight of the total aggregate) (examples 7 and 8), the fifth variant for the case
  • the intervals or, more specifically, the periods of time during which individual components are added, as well as the amounts of these components, are determined by the technological requirements for hardened concrete and its mechanical and physical parameters and may vary within the whole intervals stated below.
  • the upper fraction of the recyclate(s) and/or of the natural aggregate in other examples may be higher or lower than 20 mm.
  • brick, ceramic, concrete or mixed recyclate made from inert construction and demolition waste with an upper fraction of 20 mm e.g. one-fractional recyclate with a fraction of 0 to 20 mm, two-fractional recyclate with fractions of 0 to 8 mm and 8 to 20 mm, or three-fractional recyclate with fractions of 0 to 4 mm, 4 to 8 mm and 8 to 20 mm
  • an industrial mixer for 5 to 39.9 seconds (preferably for 5 to 19.9 seconds).
  • the whole dose of microsilica and/or substituent(s) thereof is added to it under constant mixing within 1 to 15 seconds, preferably within 1 to 9.9 seconds, and the mixture thus prepared is mixed for a further 5 to 39.9 seconds.
  • the whole dose of cement or the whole dose of cement and substituent(s) thereof is added to the mixture under constant mixing within 1 to 20 seconds, preferably within 1 to 9.9 seconds, and the mixture thus prepared is mixed for a further 5 to 39.9 seconds.
  • this mixture is sprinkled with the whole dose of mixing water (which, if appropriate, contains at least one additive for concrete) under constant mixing within 5 to 39.9 seconds or the whole dose of mixing water (which, if appropriate, contains at least one additive for concrete) is sprayed on it within 5 to 39.9 seconds.
  • fresh concrete is prepared, in which 100 % by weight of the aggregate is composed of recyclate from inert construction and demolition waste.
  • the fresh concretes thus prepared were subjected to consistency tests by a method according to EN 12350-2 and air content was measured by a method according to EN 12350-7.
  • test bodies were removed from the molds on the following day and stored for the appropriate tests in an air-conditioned chamber at a temperature of 20 ⁇ 2 ° C and a relative humidity above 95 %. Parameters measured during these tests are summarized in Table 2.
  • chloride content in this concrete was determined by calculation according to EN 196-2 and EN 1744-1 , the content of natural radionuclides and mass activity index were determined according to the procedure of Regulation No. 307/2002 Coll of the State Office for Nuclear Safety on radiation protection, as amended, whereby both these parameters meet the requirements of this Regulation for use for buildings with residential rooms or spaces (mass activity 226 Ra ⁇ 150 Bq.kg 1 , mass activity index I ⁇ 0.5).
  • mass activity index I ⁇ 0.5 mass activity index
  • Table 4 shows the strength classes of concrete to which the respective concretes belong due to their mechanical-physical parameters and the classification classes of specification of use of these concretes according to CSN (Czech Technical Standard) EN 206 (see Table 5).
  • brick, ceramic or mixed recyclate from inert construction and demolition waste with an upper fraction of 20 mm e.g. one-fractional recyclate with a fraction of 0 to 20 mm, two-fractional recyclate with fractions of 0 to 8 mm and 8 to 20 mm, or three-fractional recyclate with fractions of 0 to 4 mm, 4 to 8 mm and 8 to 20 mm
  • an industrial mixer for 5 to 39.9 seconds (preferably for 5 to 19.9 seconds).
  • concrete recyclate with an upper fraction of 20 mm e.g., one- fractional concrete recyclate with a fraction of 0 to 20 mm, two-fractional concrete recyclate with fractions of 0 to 8 mm and 8 to 20 mm, or three- fractional concrete recyclate with fractions of 0 to 4 mm, 4 to 8 mm and 8 to 20 mm
  • natural aggregate with an upper fraction of 20 mm, preferably 8 mm, or fine aggregate with an upper fraction of 4 mm (up to 40 % by weight of the total aggregate in the concrete) is added to it under constant mixing and the mixture thus obtained is mixed for a further 5 to 39.9 seconds.
  • the whole dose of microsilica and/or substituent(s) thereof is added to it under constant mixing within 1 to 15 seconds, preferably within 1 to 9.9 seconds, and the mixture thus prepared is mixed for an additional 5 to 39.9 seconds.
  • the whole dose of cement or the whole dose of cement and substituent(s) thereof is added to it under constant mixing within 1 to 20 seconds, preferably within 1 to 9.9 seconds, and the mixture thus prepared is mixed for a further 5 to
  • this mixture is sprinkled with the whole dose of mixing water (which, if necessary, contains at least one additive for concrete) under constant mixing within 5 to 39.9 seconds or the whole dose of the mixing water (which, if necessary, contains at least one additive for concrete) is sprayed on it within 5 to 39.9 seconds.
  • fresh concrete is prepared, in which 60 to 100 % by weight of the aggregate is composed of recyclate from inert construction and demolition waste.
  • chloride content in this concrete was determined by calculation according to EN 196-2 and EN 1744-1 , the content of natural radionuclides and mass activity index were determined following the procedure of Decree No. 307/2002 Coll on radiation protection of the State Office for Nuclear Safety, as amended, whereby all these parameters meet the requirements of this Decree for use in buildings with residential rooms or spaces (mass activity 226 Ra ⁇ 150 Bq.kg 1 , mass activity index I ⁇ 0.5).
  • mass activity index I ⁇ 0.5 mass activity index
  • Table 8 shows strength classes of concrete to which the respective concretes belong due to their mechanical-physical parameters and the classification classes of specification of the use of these concretes according to CSN (Czech Technical Standard) EN 206 (see Table 5).
  • recyclate made from inert construction and demolition waste with an upper fraction of 20 mm e.g. one-fractional recyclate with a fraction of 0 to 20 mm, two-fractional recyclate with fractions of 0 to 8 mm and 8 to 20 mm, or three-fractional recyclate with fractions of 0 to 4 mm, 4 to 8 mm and 8 to 20 mm
  • the first type brick, ceramic or mixed recyclate, alternatively concrete recyclate
  • recyclate from inert construction and demolition waste with an upper fraction of 20 mm e.g.
  • one-fractional recyclate with a fraction of 0 to 20 mm, two-fractional recyclate with fractions of 0 to 8 mm and 8 to 20 mm, or three-fractional recyclate with fractions of 0 to 4 mm, 4 to 8 mm and 8 to 20 mm) of the second type (brick, ceramic or mixed recyclate, optionally concrete recyclate) is added under constant mixing, whereby the recyclate being added is made from inert construction and demolition waste of a different type than the recyclate to which it is added, and the mixture thus prepared is mixed for a further 5 to 39.9 seconds.
  • the whole dose of microsilica and/or substituent(s) thereof is added to it under constant mixing within 1 to 15 seconds, preferably within 1 to 9.9 seconds and the mixture thus prepared is mixed for a further 5 to 39.9 seconds.
  • the whole dose of cement or the whole dose of cement and substituent(s) thereof is added to it under constant mixing within 1 to 20 seconds, preferably within 1 to 9.9 seconds, and the mixture thus prepared is mixed for a further 5 to 39.9 seconds.
  • this mixture is sprinkled with the whole dose of mixing water (which, if necessary, contains at least one additive for concrete) under constant mixing within 5 to 39.9 seconds or the whole dose of mixing water (which, if necessary, contains at least one additive for concrete) is sprayed on it within 5 to 39.9 seconds.
  • fresh concrete is prepared, in which 100 % by weight of the aggregate is composed of recyclate from inert construction and demolition waste.
  • chloride content in this concrete was determined by calculation according to EN 196-2 and EN 1744-1 , the content of natural radionuclides and mass activity index were determined following the procedure of Decree No. 307/2002 Coll on radiation protection of the State Office for Nuclear Safety, as amended, whereby all these parameters meet the requirements of this Decree for use in buildings with residential rooms or spaces (mass activity 226 Ra ⁇ 150 Bq.kg 1 , mass activity index I ⁇ 0.5). According to the procedure in EN 12457 and Decree of the Ministry of Environment No. 294/2005 Coll its ecotoxicity was found to be complying with the requirements. The criteria for determination of ecotoxicity are shown in Table 3, example 2.
  • Table 1 1 shows the strength classes of concretes into which the respective concrete belongs due to its mechanical-physical parameters and classification classes of specification of the use of these concrete according to CSN EN 206 (see Table 5).
  • recyclate made from inert construction and demolition waste having an upper fraction of 20 mm e.g. one-fractional recyclate with a fraction of 0 to 20 mm, two-fractional recyclate with fractions of 0 to 8 mm and 8 to 20 mm, or three-fractional recyclate with fractions of 0 to 4 mm, 4 to 8 mm and 8 to 20 mm
  • the first type brick, ceramic or mixed recyclate, optionally concrete recyclate
  • recyclate from inert construction and demolition waste with an upper fraction of 20 mm e.g.
  • one-fractional recyclate with a fraction of 0 to 20 mm, two-fractional recyclate with fractions of 0 to 8 mm and 8 to 20 mm, or three-fractional recyclate with fractions of 0 to 4 mm, 4 to 8 mm and 8 to 20 mm) of the second type (brick, ceramic or mixed recyclate, optionally concrete recyclate) is added to it under constant mixing, whereby the recyclate being added is made from inert construction and demolition waste of a different type than the recyclate to which it is added, and the mixture thus prepared is mixed for a further 5 to 39.9 seconds.
  • recyclate from inert construction and demolition waste with an upper fraction of 20 mm e.g.
  • the whole dose of microsilica and/or its substituent(s) is added to it under constant mixing within 1 to 15 seconds, preferably within 1 to 9.9 seconds and the mixture thus prepared is mixed for a further 5 to 39.9 seconds.
  • the whole dose of cement or the whole dose of cement and substituent(s) thereof is added to it under constant mixing within 1 to 20 seconds, preferably within 1 to 9.9 seconds, and the mixture thus prepared is mixed for a further 5 to 39.9 seconds.
  • this mixture is sprinkled with the whole dose of mixing water (which, if necessary, contains at least one additive for concrete) under constant mixing within 5 to 39.9 seconds or the whole dose of the mixing water (which, if necessary contains at least one additive for concrete) is sprayed on it within 5 to 39.9 seconds.
  • fresh concrete is prepared, in which at least 60 % by weight of the aggregate consists of recyclate from inert construction and demolition waste.
  • chloride content in this concrete was determined by calculation according to EN 196-2 and EN 1744-1 , the content of natural radionuclides and mass activity index were determined following the procedure of Decree No. 307/2002 Coll on radiation protection of the State Office for Nuclear Safety, as amended, whereby all these parameters meet the requirements of this Decree for use in buildings with residential rooms or spaces (mass activity 226 Ra ⁇ 150 Bq.kg 1 , mass activity index I ⁇ 0.5). According to the procedure in EN 12457 and Decree of the Ministry of Environment No. 294/2005 Coll its ecotoxicity was found to be complying with the requirements. The criteria for determination of ecotoxicity are shown in Table 3, example 2.
  • Table 14 shows the strength classes of concrete to which the respective concrete belongs due to its mechanical-physical parameters and classification classes of specification of the use of these concrete according to CSN (Czech Technical Standard) EN 206 (see Table 5).
  • concrete recyclate having an upper fraction of 20 mm (e.g. one-fractional recyclate with a fraction of 0 to 20 mm, two-fractional recyclate with fractions of 0 to 8 mm and 8 to 20 mm, or three-fractional recyclate with fractions of 0 to 4 mm, 4 to 8 mm and 8 to 20 mm) is mixed in an industrial mixer for 5 to 39.9 seconds (preferably for 5 to 19.9 seconds).
  • natural aggregate with an upper fraction of 20 mm up to 40 % by weight of the total aggregate in concrete
  • the mixture thus obtained is mixed for a further 5 to 39.9 seconds (preferably for 5 to 19.9 seconds).
  • the whole dose of microsilica and/or of substituent(s) thereof is added to it under constant mixing within 1 to 15 seconds, preferably within 1 to 9.9 seconds, and the mixture thus obtained is mixed for a further 5 to 39.9 seconds.
  • the whole dose of cement or the whole dose of cement and substituent(s) thereof is added to it under constant mixing within 1 to 20 seconds, preferably within 1 to 9.9 seconds, and the mixture thus prepared is mixed for a further 5 to 39.9 seconds.
  • this mixture is sprinkled with the whole dose of mixing water (which, if necessary contains at least one additive for concrete) under constant mixing for 5 to 39.9 seconds or the whole dose of the mixing water (which, if necessary contains at least one additive for concrete) is sprayed on it within 5 to 39.9 seconds.
  • fresh concrete is prepared, in which at least 60 % by weight of the aggregate is composed of recyclate from inert construction and demolition waste.
  • chloride content in this concrete was determined by calculation according to EN 196-2 and EN 1744-1 , the content of natural radionuclides and mass activity index were determined following the procedure of Decree No. 307/2002 Coll on radiation protection of the State Office for Nuclear Safety, as amended, whereby all these parameters meet the requirements of this Decree for use in buildings with residential rooms or spaces (mass activity 226 Ra ⁇ 150 Bq.kg 1 , mass activity index I ⁇ 0.5). According to the procedure in EN 12457 and Decree of the Ministry of Environment No. 294/2005 Coll its ecotoxicity was found to be complying with the requirements. The criteria for determination of ecotoxicity are summarized in Table 3, example 2.
  • Table 17 shows the strength classes of concrete to which the respective concrete belongs due to its mechanical-physical parameters and classification classes of specification of the use of these concretes according to CSN (Czech Technical Standard) EN 206 (see Table 5).
  • brick or ceramic or mixed recyclate from inert construction and demolition waste with concrete recyclate and with up to 40 % by weight of natural aggregate.
  • a brick or ceramic or mixed recyclate from inert construction and demolition waste is added to the mixer first, afterwards it is followed by concrete recyclate and then by natural aggregate.
  • Brick, ceramic or mixed recyclate from inert construction and demolition waste have similar characteristics and behavior and can therefore be interchanged or mixed.
  • the whole dose of microsilica and/or substituent(s) thereof, as well as the whole dose of the aggregate may be divided into two or more smaller portions (equal or different), whereby the individual portions of the dose of microsilica and/or substituent(s) thereof are added one by one after the addition of the individual portions of the whole dose of the aggregate, or recyclate from inert construction and demolition waste of different types or and/or fractions, or at least some parts of the dose of microsilica and/or substituent(s) thereof may be added simultaneously with some parts of the whole dose of the aggregate or recyclate - see examples 11 and 12 below.
  • the first part of the whole dose of aggregate composed of recyclate made from inert construction and demolition waste is mixed in an industrial mixer for 5 to 39.9 seconds (preferably for 5 to 19.9 seconds), whereupon the first part of the whole dose of microsilica and/or of substituent(s) thereof is added to it within 1 to 15 seconds, preferably within 1 to 9.9 seconds, and the mixture thus obtained is mixed for 5 to 39.9 seconds (preferably for 5 to 19.9 seconds).
  • the remaining part of the aggregate consisting of recyclate from inert construction and demolition waste or natural aggregate is added to it under constant mixing and the mixture thus obtained is mixed for 5 to 39.9 seconds (preferably for 5 to
  • the second part of the dose of microsilica and/or of substituent(s) thereof is added to it within 1 to 15 seconds, preferably within 1 to
  • the whole dose of the aggregate is 1000 to 2300 kg/m 3 of fresh concrete and the whole dose of microsilica and/or of substituent(s) thereof is 10 to 27.9 kg/m 3 of fresh concrete.
  • the mixture thus obtained is mixed for a further 5 to 39.9 seconds.
  • the whole dose of cement or of cement and substituent(s) thereof is added to it under constant mixing within 1 to 20 seconds, preferably within 1 to 9.9 seconds, and the mixture thus prepared is mixed for another 5 to 39.9 seconds.
  • the mixture is sprinkled with the whole dose of mixing water (which, if necessary, contains at least one addition for concrete) under constant mixing within 5 to 39.9 seconds or the whole dose of the mixing water (which, if necessary, contains at least one addition for concrete) is sprayed on it within 5 to 39.9 seconds.
  • fresh concrete is prepared, in which 100 % by weight of the aggregate is composed of recyclate made from inert construction and demolition waste.
  • Both parts of the whole dose of the aggregate may consist of the same type of recyclate made from inert construction and demolition waste or may differ in fraction and/or the type of recyclate.
  • the first part of the whole dose of the aggregate composed of recyclate made from inert construction and demolition waste is mixed in an industrial mixer for 5 to 39.9 seconds
  • the first part of the whole dose of microsilica and/or of substituent(s) thereof is added to it within 1 to 15 seconds, preferably within 1 to 9.9 seconds, and the mixture thus obtained is mixed for 5 to 39.9 seconds (preferably for 5 to 19.9 seconds).
  • the second part of the whole dose of the aggregate composed of recyclate from inert construction and demolition waste or natural aggregate is added to it under constant mixing and the mixture thus obtained is mixed for 5 to 39.9 seconds (preferably for 5 to 19.9 seconds), whereupon the second part of the dose of microsilica and/or of substituent(s) thereof is added to it within 1 to 15 seconds, preferably 1 to 9.9 seconds, and the mixture thus obtained is mixed for 5 to 39.9 seconds (preferably for 5 to 19.9 seconds).
  • the third part of the aggregate composed of recyclate from inert construction and demolition waste or natural aggregate is added to it under constant mixing and the mixture thus obtained is mixed for 5 to 39.9 seconds (preferably for 5 to 19.9 seconds) and then the third part of the dose of microsilica and/or substituent(s) thereof is added to it within 1 to 15 seconds, preferably within 1 to 9.9 seconds, and the mixture thus obtained is mixed for 5 to 39.9 seconds (preferably for 5 to 19.9 seconds).
  • the whole dose of the aggregate is 1000 to 2300 kg/m 3 of fresh concrete and the whole dose of microsilica and/or substituent(s) thereof is 10 to 27.9 kg/m 3 of fresh concrete.
  • the mixture thus obtained is further mixed for 5 to 39.9 seconds.
  • the whole dose of cement or cement and substituent(s) thereof is added to it under constant mixing within 1 to 20 seconds, preferably within 1 to 9.9 seconds, and the mixture thus prepared is mixed for a further 5 to 39.9 seconds. Subsequently, this mixture is sprinkled with the whole dose of mixing water (which, if necessary, contains at least one additive for concrete ) under constant mixing wihin 5 to 39.9 seconds or the whole dose of the mixing water (which, if necessary, contains at least one additive for concrete,) is sprayed on it within 5 to 39.9 seconds. After another 5 to 160 seconds of mixing, fresh concrete is prepared, in which at least 100 % by weight of the aggregate is composed of recyclate from inert construction and demolition waste.
  • Different parts of the whole dose of the aggregate may consist of the same type of recyclate from inert construction and demolition waste or may differ from each other in fraction and/or the type of recyclate.
  • reinforcement fibers of at least one type which reinforce the structure of the concrete and thereby improve some of its properties, e.g. tensile strength and flexural strength.
  • Suitable reinforcing fibers are, e.g., polypropylene (PP) fibers, polyvinyl alcohol (PVA) fibers, blends of polypropylene and polyethylene (PLV) fibers, cellulose fibers, steel fibers, glass fibers, carbon fibers, Kevlar fibers etc. These fibers are preferably added to the concrete mixture after the addition of microsilica and/or substituent(s) thereof and after thorough mixing of the mixture obtained.
  • the total amount of all reinforcing fibers is 0.6 to 1.2 kg/m 3 of fresh concrete, in the case of steel and similar fibers the total amount is up to 25 kg/m 3 of fresh concrete.
  • the reinforcing fibers are added to the concrete mixture under constant mixing within 5 to 30 seconds, which ensures their uniform distribution in the concrete.
  • fresh concrete with a finer texture is prepared using the same processes, sometimes referred to as cement mortar or concrete mortar.
  • the 0 to 20 mm aggregate fraction described in the above examples is not limiting for the implementation of the invention, since both natural aggregate and recyclate from inert construction and demolition waste may have a higher limit of the upper fraction.
  • All the concretes according to the invention are designed for both manual and machine processing (including shotcrete) and are suitable for conventional concrete structures from both plain concrete and ferroconcrete.
  • fresh concrete transport concrete
  • these concretes can be also used for the production of concrete products and prefabricated elements, e.g., concrete blocks and bricks, paving cobbles, slabs, blocks, curbs, various elements of garden architecture, ceiling beams and inserts, etc.
  • brick, ceramic, concrete or mixed recyclate from inert construction and demolition waste with an upper fraction up to 8 mm, or two-fractional recyclate with fractions of 0 to 4 mm and 4 to 8 mm is mixed in an industrial mixer with a forced circulation system for 5 to 40 seconds, preferably for 5 to 20 seconds.
  • microsilica and/or at least one substituent thereof is added to it under constant mixing within 1 to 15 seconds, preferably within 1 to 10 seconds, and the mixture thus obtained is mixed for another 5 to 80 seconds, preferably for 5 to 40 seconds.
  • cement is added to it under constant mixing within 1 to 20 seconds, preferably within 1 to 10 seconds, or cement and at least one substituent thereof are added to it one by one in any order or simultaneously within 1 to 15 seconds, preferably within 1 to 10 seconds, and the mixture thus obtained is mixed for another 5 to 80 seconds, preferably 5 to 40 seconds.
  • this mixture is sprinkled with an entire dose of mixing water (which, if required, contains at least one additive for concrete) under constant mixing within 5 to 60 seconds, preferably within 5 to 40 seconds, or the entire dose of the mixing water is sprayed on the mixture within 5 to 60 seconds, preferably within 5 to 40 seconds.
  • fresh concrete is prepared, in which at least 55 % by weight of aggregate consists of recyclate from inert construction and demolition waste, whereby the aggregate grains, especially of the recyclate grains, are covered and their pores are filled with a mixture of microsilica and/or at least one substituent thereof and fine pozzolanic powder, which is produced by the rubbing of the recyclate grains in the aggregate, the aggregate grains thus treated are further covered with cement paste which is formed by moistening cement (optionally combined with at least one substituent thereof).
  • finely ground recycled waste from inert construction and demolition waste is added to the mixture before adding cement, preferably together with microsilica.
  • the aggregate grains, especially the recyclate grains are covered and their pores are filled with a mixture of microsilica and/or at least one substituent thereof, fine pozzolanic powder, which is produced by the rubbing of the aggregate and the finely ground recyclate from inert construction and demolition waste, the aggregate grains thus treated are further covered with cement paste, which is formed by moistening cement (optionally combined with at least one substituent thereof).
  • the fresh concretes prepared in this manner were subjected to a consistency test according to EN 12350-2 and air content measurement according to EN 12350-7.
  • test bodies were removed from the molds on the following day and stored for the appropriate tests in an air-conditioned chamber at a temperature of 20 ⁇ 2 °C and at relative humidity above 95 %. The parameters measured during these tests are summarized in Table 3.
  • Fresh concretes for 3D printing technology were tested being laid out by a six-axis robot, which was equipped with a printhead with a nozzle having a diameter of 20 mm, into which these fresh concretes were supplied by means of a screw pump with adjustable power which was gradually optimized with respect to the speed of the robot.
  • tests of the dimensional stability of the printed layer after printing and after the application of other layers were preformed, as well as tests of the hardening speed of the concrete mixture, tests for the load-bearing capacity of the printed layer before and during hardening, and the pumpability of the concrete mixture.
  • Shape stability was checked with a caliper after printing the layer and after loading it with additional layers, the solidification rate was determined by a penetrating needle on a Vicat machine, the load capacity of the layer was verified by means of the caliper, wherein the layer was loaded with additional layers until its cross section was deformed by 2 +/- 1 mm.
  • the tests were performed in a laboratory environment with a constant temperature of 20 +/- 1 ° C and a relative humidity of 60 +/- 5%. In all variants, the applied layer retained its shape, while having sufficient strength for laying another layer.
  • chloride content in these concretes was determined by calculation according to EN 196-2 and EN 1744-1 , the content of natural radionuclides and mass activity index were determined according to the procedure of Regulation No. 307/2002 Coll of the State Office for Nuclear Safety on radiation protection, as amended, whereby all these parameters meet the requirements of this Regulation for use for buildings with residential rooms or spaces (mass activity 226 Ra ⁇ 150 Bq.kg 1 , mass activity index I ⁇ 0.5).
  • mass activity index I ⁇ 0.5 mass activity index
  • Table 20 shows the strength classes of concrete to which the respective concretes belong due to their mechanical-physical parameters and the classification classes of specification of use of these concretes according to CSN (Czech Technical Standard) EN 206 - see Table 5 above.
  • CSN Chech Technical Standard

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Abstract

L'invention concerne un procédé de préparation de 1 m3 de béton frais à l'aide d'un recyclat issu de déchets de construction et de démolition inertes, dont 1 000 à 2 300 kg d'agrégat. Selon le procédé, 30 % en poids à 100 % en poids de l'agrégat est constitué d'un recyclat issu de déchets de construction et de démolition inertes et est mélangé à 5 à 65 kg de microsilice ou son ou ses substituants ou un mélange de microsilice et d'au moins un de ses substituants dans un mélangeur industriel pendant 5 à 80 secondes. Grâce à la friction des grains d'agrégat, les grains du recyclat issu de déchets de construction et de démolition inertes sont frottés de manière intensive, ce qui entraîne par conséquent une augmentation de la surface spécifique du recyclat et la production d'une fine poudre pouzzolanique, moyennant quoi la microsilice et/ou son ou ses substituants, conjointement avec la poudre pouzzolanique, recouvrent les particules d'agrégat et remplissent les pores de celles-ci. Après un mélange complet, 135 à 580 kg de ciment sont ajoutés au mélange ainsi préparé sous mélange constant pendant 1 à 20 secondes, avantageusement pendant 1 à 9,9 secondes, ou du ciment, et au moins un de ses substituants en une quantité totale de 135 à 600 kg sont ajoutés à celui-ci, tour à tour, dans n'importe quel ordre ou simultanément sous mélange constant pendant 1 à 20 secondes, et le mélange ainsi préparé est mélangé pendant 5 à 80 secondes supplémentaires, après quoi il est arrosé de 50 à 500 kg d'eau de mélange sous mélange constant en 5 à 60 secondes, ou il est pulvérisé avec cette quantité d'eau de mélange pendant 5 à 60 secondes, moyennant quoi la surface du ciment et éventuellement de son ou ses substituants est progressivement humidifiée et la pâte de ciment ainsi obtenue est progressivement collée aux particules d'agrégat déjà recouvertes par le mélange de microsilice et/ou de son ou ses substituants et de poudre pouzzolanique, et après 5 à 160 secondes supplémentaires de mélange, du béton frais est préparé. L'invention concerne également du béton frais préparé par ce procédé. L'invention concerne en outre un mélange sec pour la préparation dudit béton.
PCT/CZ2020/050046 2019-06-14 2020-06-12 Mélange sec pour la préparation de béton, béton frais et procédé de préparation de béton frais WO2020249145A1 (fr)

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CZPV2019-375 2019-06-14
CZ2019375A CZ308833B6 (cs) 2019-06-14 2019-06-14 Beton a způsob pro jeho přípravu
CZ2020307 2020-05-29
CZPV2020-307 2020-05-29

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WO2020249145A1 true WO2020249145A1 (fr) 2020-12-17

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CN113003994A (zh) * 2020-12-29 2021-06-22 中建科技贵州有限公司 一种燃煤炉渣混凝土
CN113277826A (zh) * 2021-06-15 2021-08-20 太原钢铁(集团)有限公司 一种利用陶粒制备蒸压粉煤灰标砖的方法
CN114409343A (zh) * 2022-02-21 2022-04-29 湖南城市学院 一种高致密性混凝土及其制备方法
CN115010428A (zh) * 2022-05-27 2022-09-06 盈创新材料(苏州)有限公司 建筑3d打印材料、其制备方法和应用以及制品

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Publication number Priority date Publication date Assignee Title
CN113003994A (zh) * 2020-12-29 2021-06-22 中建科技贵州有限公司 一种燃煤炉渣混凝土
CN113277826A (zh) * 2021-06-15 2021-08-20 太原钢铁(集团)有限公司 一种利用陶粒制备蒸压粉煤灰标砖的方法
CN114409343A (zh) * 2022-02-21 2022-04-29 湖南城市学院 一种高致密性混凝土及其制备方法
CN115010428A (zh) * 2022-05-27 2022-09-06 盈创新材料(苏州)有限公司 建筑3d打印材料、其制备方法和应用以及制品

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