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
  • C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
  • C04B18/04—Waste materials; Refuse
  • C04B18/16—Waste materials; Refuse from building or ceramic industry
  • C04B18/167—Recycled materials, i.e. waste materials reused in the production of the same materials
• • 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
  • C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators or shrinkage compensating agents
  • C04B22/02—Elements
  • C04B22/04—Metals, e.g. aluminium used as blowing agent
• • 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
  • 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
  • C04B28/10—Lime cements or magnesium oxide cements
  • C04B28/12—Hydraulic lime
• • 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
  • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
  • C04B38/02—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by adding chemical blowing agents
• • 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 present invention relates to a mixture for use in the processing of an aerated concrete recyclate, to a building element made from the aerated concrete recyclate and to a process for production the same.
• An aerated concrete or an autoclaved aerated concrete is a type of a lightweight concrete with good thermal and sound insulation properties.
• this material has been widely used, for example, in the production of blocks such as Ytong* produced by Xella, or various aerated concrete shaped elements.
• the advantage of the aerated concrete blocks is their relatively low weight and the fact that their size can be easily adjusted during construction, for example by cutting, either by a machine or simply by using a hand saw. These modifications generate a large amount of waste on construction sites, the use of which depends not only on its purity but also on the size of the particles forming it.
• the present invention relates to a dry mixture comprising a cement component, a lime component, an expander component, and a mixing water. More particularly, said mixture comprises 60 to 90 wt. % of a cement component, 4 to 35 wt. % of a lime component and 0.5 to 5.0 wt. % of an expander component, always based on the total weight of the mixture.
• cement component preferably a common Portland cement CEM 142.5 R can be used, for example, as the lime component, a white lime CL 90-Q can be used, for example, and as the expander component, a specially treated aluminium powder such as Expandit 10, produced by Grimm Metallpulver GmbH, Roth, Germany, is used. All of the above materials are mentioned herein as the specific examples only, without limiting the scope of the present invention in any way.
• the aerated concrete recyclate is mixed with water in a suitable proportion by weight to the solids and the above mixture is added to the resulting slurry, after thorough mixing of all the components and approximately 40 minutes, a material can be obtained which has parameters similar to those of the aerated concrete.
• Said water to solids ratio is commonly referred to in the art as the 'water coefficient' and expresses the ratio by weight of water to all the solids in the resulting mixture.
• the value of the water coefficient should be in the range from 0.50 to 0.55, preferably from 0.52 to 0.53.
• the amount of the mixture according to the present Invention which is added to the aerated concrete recyclate is selected so that the weight ratio of the aerated concrete recyclate itself, i.e. without added water, and the mixture according to the present invention is in the range from 1:3 to 3:1.
• a further advantage of the process according to the present invention is that it works with a liquid mixture which is poured into moulds from which a building element of the desired shape is removed after the mixture has solidified.
• this process is advantageous in that the step of cutting the body out of the block of the aerated concrete is eliminated. Omitting the step of cutting the body from the manufactured aerated concrete block not only reduces production costs, but also eliminates the aerated concrete waste (in the form of cuttings and dust particles) that is necessarily generated during the cutting process.
• said mixture may further comprise 3-15 wt. % of a filler, such as ground limestone, and up to 1 wt. % of refining component, such as a viscosity reducing agent, such as (superplasticizer) Peramin 149 S, for example.
• a filler such as ground limestone
• refining component such as a viscosity reducing agent, such as (superplasticizer) Peramin 149 S, for example.
• Another aspect of the present invention relates to the use of the mixture according to the first aspect of the invention in the processing of the aerated concrete recyclate.
• the 'aerated concrete recyclate' in this text is intended to mean both the aerated concrete waste from the actual production of the aerated concrete or from working with the aerated concrete products on the construction sites and the aerated concrete obtained by sorting it from demolition rubble.
• the aerated concrete recyclate may arise during the production of the aerated concrete such that the product produced has not reached the required parameters and has not passed a quality control.
• the term aerated concrete recyclate includes non-conforming pieces from production of the aerated concrete, regardless they are come from the products that do not meet shape or accuracy requirements, or the products that do not meet strength requirements, etc.
• the actual processing of the aerated concrete recyclate is therefore carried out by crushing the aerated concrete recyclate, e.g. in a hammer or jaw crusher, to a grain size of less than 1 mm. If necessary, separation of unwanted construction waste components such as paper, wood, metal, glass, etc. can be ensured during the crushing process.
• the crushed aerated concrete recyclate is gradually added to the water in the mixing device.
• the mixture according to the first aspect of the present Invention is added.
• the resulting mixture is mixed until a homogeneous mass is formed.
• the mixing device is turned off, a sample is taken and a spillage test is performed on a PVC pad to determine the exact amount of water to be used, which is dependent on the moisture content of the starting recyclate.
• the spillage test shall be carried out in accordance with EN 12706 using a spillage cylinder with an internal diameter of 30 mm and a height of 50 mm.
• the homogeneous mass should have such a spillage that it fills the mould completely after pouring into the mould.
• the mixture should flow into all the 'nooks and crannies' of the mould, including the comers, without the need of use of a vibrating equipment, etc
• the mixture should not be too diluted, otherwise it would take an unreasonably long time to cure and dry the mixture.
• the spillage value of the prepared homogeneous mass should be between 7.5 and 8.5 cm. If the measured spillage value is within this range, then no water needs to be added to the prepared mixture. If the spillage value is less than 7.5 cm, then the prepared mass should be diluted by adding more water.
• the ready-mixed mixture should be thickened by adding an additional quantity of the aerated concrete recyclate. In both cases, the mixture is again mixed thoroughly to obtain a homogeneous mass, and the spillage is checked again and, if necessary, readjusted using the above procedure. Once the desired spillage value is achieved, the liquid mixture is poured into the prepared moulds. The processing time of the prepared mixture is 5 to 10 minutes, followed by the spontaneous expansion process which takes 100 to 120 minutes. After the mixture sets, it is advisable to use a suitable tool, such as a saw or wire, to remove the excess mass. Curing the mixture takes approximately 24 hours, after which time the exact dimensions of the product can be adjusted by cutting, If necessary.
• the product reaches its final strength after approximately 28 days, during which time the product dries out and the associated weight loss occurs.
• Another significant advantage of the method according to the invention is that the time- and energy-consuming step of drying the aerated concrete recyclate, which is carried out in the currently used recycling processes, is eliminated.
• Figure 1 is an image showing the profile structure of a block manufactured by the process of the invention and tested in Example 3
• Figure 2 is the block from Figure 1 indicating the locations from which the samples were cut for testing in Example 3.
• Example 1
• the mixing device was switched off and a sample of the mixture was taken from the device in order to carry out a spillage test (according to EN 12706: using the spillage cylinder with an internal diameter of 30 mm and a height of 50 mm, as described above). Based on the test results, where the observed spillage was less than 7.5 cm, additional 100 ml of water were added to the mixture.
• the mixture was then briefly stirred and poured into prepared moulds of a hardened PVC or steel treated with a separation oil. After a period of approximately 10 minutes, the expansion process started spontaneously and was completed after approximately 110 minutes. After a period of 24 hours from the start of the expansion process, it was possible to remove the manufactured aerated concrete element from the mould, at which time it was possible to walk on the element. The final strength of the element was achieved after 28 days, during which time the product dried out, which also led to a reduction in its weight.
• the mixing device was switched off and a sample of the mixture was taken from the device in order to carry out a spillage test (according to EN 12706: using the spillage cylinder with an internal diameter of 30 mm and a height of 50 mm, as described above). Based on the test result, where the observed spillage was less than 7.5 cm, additional 100 ml of water were added to the mixture.
• the mixture was further briefly stirred and poured into prepared moulds made of a steel and pre-treated with a separation oil. After a period of approximately 5 minutes, the expansion process started spontaneously and was completed after approximately 120 minutes.
• the pillar block manufactured using the process according to the present invention was subjected to the mechanical tests according to EN 772-1+A1 Compressive strength and EN 772-13 Bulk weight for testing aerated concrete.
• the compressive strength specimens were tested in a press in the direction of mass growth (as AAC lintels are tested) and perpendicular to the direction of mass growth (as conventional aerated concrete blocks are tested).

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Structural Engineering (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Civil Engineering (AREA)
• Inorganic Chemistry (AREA)
• Environmental & Geological Engineering (AREA)
• General Chemical & Material Sciences (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)
• Processing Of Solid Wastes (AREA)
• Porous Artificial Stone Or Porous Ceramic Products (AREA)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

Country Status (2)

Family Cites Families (7)

• 2023
  • 2023-10-31 CZ CZ2023-417A patent/CZ310525B6/cs unknown
• 2024
  • 2024-10-23 WO PCT/CZ2024/050066 patent/WO2025093069A2/en active Pending

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