• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention relates to a process for recycling demolition concrete to obtain clean aggregates which is remarkable in that it comprises at least the following steps: - first crushing of demolition concrete or deconstruction to obtain 0/90 aggregate, - stripping of said 0/90 aggregate, - screening of said 0/90 aggregate to obtain a first fraction 40/90 and a second fraction 0/40, - second crushing in order to reduce the first fraction 40/90 into a new first fraction 0/25, - stripping of the new first fraction 0/25, - screening of the new first fraction 0/25 to extract the sand 0/4 from the latter and isolate the gravel 4/25, - extraction of particles smaller than 63 µm from the sand 0 / 4, in order to recover only 0.063 / 4 sand which will finally be wrung out and piled up, - immersion of the 4/25 gravel, - screening of the 4/25 gravel in order to produce the following three cuts: 4/10 gravel, d he chippings 10/20 and chippings 20/25, - rapid recarbonation of the sand 0.063 / 4 and chippings 4/10 and 10/20 obtained.
    公开号:FR3081863A1
    申请号:FR1854740
    申请日:2018-05-31
    公开日:2019-12-06
    发明作者:Stephane Poullard
    申请人:Sarl Poullard；
    IPC主号:
    专利说明:

    Technical area
    The present invention relates to the general field of building and public works (Building and Public Works). More specifically, it relates to a process for recycling demolition or deconstruction concrete.
    Prior art
    With around two tonnes per person per year, concrete is the most consumed manufactured material in the world. The most important part of the concrete is made up of aggregates: about 2/3 of the mass. In addition, the manufacture of concrete currently represents around 40% of the total consumption of aggregates.
    We then understand that it would be interesting to be able to produce aggregates from the recycling of materials from demolition or deconstruction.
    In France, deconstruction in the building and public works sector represents an input of nearly 300 million tonnes of materials per year, including around 36% of concrete-based products. In addition, the volume of these deconstruction materials for buildings and infrastructure is increasing and will become more and more important in the coming years. Indeed, the buildings erected during the reconstruction in the 1950s are gradually reaching the end of their life.
    Deconstructed concrete is considered as waste having a regulatory status, the exit from the status of waste being regulated by law.
    The main disadvantage of these materials from demolition or deconstruction is that only a fraction of these materials is recycled with a view to its release from waste status and its recovery. This finding goes against the reflections from the Grenelle
    1'Environment, increased awareness of society to the challenges of sustainable development and the circular economy, but also the depletion of natural deposits, difficulties in opening new quarries and therefore the increasing cost of raw materials constituting concrete.
    Statement of the invention
    The aim of the present invention is to propose a process for recycling concretes resulting from demolition or deconstruction, including the fine fraction, as constituents for new concretes.
    In accordance with the invention, a method is therefore proposed for recycling concretes resulting from the demolition or deconstruction of old structures to obtain aggregates suitable for being incorporated into new concretes of remarkable quality in that it comprises at least the following steps :
    - first crushing of demolition or deconstruction concrete to obtain 0/90 aggregate,
    - stripping of said 0/90 aggregate,
    - screening of said 0/90 aggregate to obtain a first 40/90 fraction and a second 0/40 fraction intended for use in road sub-layers,
    - second crushing in order to reduce the first fraction 40/90 into a new first fraction 0/25,
    - stripping of the new first fraction 0/25,
    - screening of the new first fraction 0/25 to extract the sand 0/4 from the latter and isolate the gravel 4/25,
    - extraction of particles smaller than 63 µm from sand 0/4, in order to recover only sand 0.063 / 4 which will finally be wrung out and piled up,
    - immersion of the 4/25 gravel to allow floating materials of the plastic and / or wood type to rise to the surface in order to be separated from said 4/25 gravel,
    - screening of 4/25 gravel in order to produce the following three cuts: 4/10 gravel, 10/20 gravel and 20/25 gravel, the latter being qualified as refusal,
    - rapid recarbonation of the sand 0.063 / 4 and gravel 4/10 and 10/20 obtained.
    The recycling process includes, before the first crushing, a visual inspection of the demolition or deconstruction concrete, when it arrives at the recycling site.
    The recycling process advantageously includes a pre-cleaning of demolition or deconstruction concrete before the first crushing.
    Preferably, the recycling process comprises a blowing of the first 40/90 stripped fraction.
    The screening of the new first fraction 0/25 and of the gravel 4/25 is advantageously carried out under water.
    The immersion of the 4/25 chippings is preferably carried out in a basin equipped with two shafts with blades rotating in opposite directions so as to set in motion the 4/25 chippings.
    According to an advantageous embodiment, the rapid recarbonation of the sand 0.063 / 4 and gravel 4/10 and 10/20 consists in passing air under pressure into and under the piles of sand 0.063 / 4 and gravel 4/10 and 10/20 obtained.
    The particles smaller than 63 μm extracted from the 0/4 sand are advantageously sent with the waste water to a clarifier, in which a flocculent agglomerates them to obtain a mud capable of descending to the bottom of said clarifier and then being discharged to a landfill.
    Best way to realize the technical invention
    The invention relates to a process for recycling concrete from the demolition of old structures in order to obtain aggregates suitable for integration into new quality concrete.
    For this, the recycling process according to the invention comprises the following different steps.
    First of all, said process advantageously includes a visual check of the concrete, resulting from the demolition or deconstruction of old structures, when they arrive at the recycling site.
    Then, said concretes are crushed using, for example, a jaw crusher, then unfrapped using a magnetic member, in order to extract the metallic elements present in said concretes and separated from the latter to following crushing, said elements being constituted, for example, of reinforcements or reinforcing bars. This first crushing then makes it possible to obtain aggregates whose particle size of the type d / D (d being the diameter in millimeters of the smallest grain and D that in millimeters of the largest) is generally equal to 0/90, the aggregate thus obtained being classically named gravel and made up of a mixture of gravel and sand.
    The term “fraction, aggregate, sand or gravel d / D” is used here to denote a fraction, of aggregate, sand or even gravel whose particle size is generally equal to d / D.
    At the outlet of the crusher, the 0/90 aggregate obtained is screened in order to eliminate from it the major part of the fine parts such as, for example, plaster residues, and to carry out its particle size classification in a first fraction 40/90 and a second fraction 0/40. The separation of the fine parts at the end of the first crushing step is particularly important, because it makes it possible to be able to recycle by the process according to the invention, non-standard concretes, without having to refuse demolition concretes containing intruders.
    The second fraction 0/40 remains reserved for uses in road underlayments and does not enter into the production of recycled products for the manufacture of concrete, since the plaster residues present in the materials from demolition are largely eliminated in this first crushing while remaining in said second fraction 0/40.
    Of course, it is always better to recycle the cleanest demolition concrete possible. For this, a pre-cleaning of demolition or deconstruction concrete may advantageously be implemented before the first crushing.
    The first fraction 40/90 represents the noble material resulting from the recycling process according to the invention, because it makes it possible to produce sand and gravel in particular for ready-mixed concrete (BPE).
    At the end of the screening, the first fraction 40/90 is unlocked using a magnet for example, in order to extract the metallic elements present in said first fraction and separated from the latter after screening.
    Then, the recycling process preferably comprises a blowing of the first fraction 40/90 de-stretched to remove a maximum of light waste such as, for example, wood or plastics.
    The recycling process then comprises a second crushing using, for example, a percussion crusher in order to reduce the first fraction 40/90 blown into a new first fraction 0/25. This second crushing has two objectives: the first objective consists in exploding the plaster residues which can still be on the surface of the first fraction, the second objective allows the aggregates to have a cubic shape which is necessary for the formulation of future concrete.
    As before, the new first fraction 0/25 is then unlocked using a magnet, for example, in order to extract the last metallic elements present in said new first fraction and separated from the latter after crushing.
    The new first fraction 0/25 is then screened, preferably under water, to extract from it the sand 0/4 and isolate and advantageously humidify the 4/25 gravel.
    The recycling process then comprises an extraction of particles smaller than 63 micrometers from the 0/4 sand, since said particles are detrimental in the manufacture of future concretes. For this, the sand 0/4 is advantageously placed inside a cyclonic vacuum cleaner, in order to recover only the sand 0.063 / 4 which will finally be wrung and piled ready to be used for the manufacture of concrete.
    Particles smaller than 63 µm are then sent with the wastewater to a clarifier. In this, a flocculent is added which agglomerates said particles smaller than 63 μm to obtain a slurry capable of descending to the bottom of the clarifier and then of being sucked by a pump in order to be evacuated to a discharge, the clean waters leaving in the overflow circuit.
    To avoid any reaction between the additives present in the composition of used concrete and the fioculant used for the treatment of sludge, an anti-foam is preferably introduced into the water to be treated.
    The recycling process according to the invention further comprises immersing in a basin the 4/25 gravel, moistened to allow floating materials of the plastic and / or wood type to rise to the surface in order to be separated from said 4/25 gravel. Said basin is preferably equipped with two shafts with blades rotating in opposite directions so as to set the 4/25 gravel in motion and to remove the last impurities present on their surface when the gravel rubs together.
    On leaving the basin, the 4/25 gravel is again screened underwater for perfect cleanliness and in order to produce the following three cuts: gravel
    4/10, 10/20 gravel and 20/25 gravel.
    The gravel 20/25, qualified as refusal, can be used for the realization of bottom form, backfill for construction site track or even to be reinjected in the circuit of the recycling process according to the invention.
    The waste water from this screening is returned to the sand 0/4 mentioned above at the level of the cyclonic vacuum cleaner to undergo the treatment described above.
    At this stage, the 0.063 / 4 sand and the 4/10 and 10/20 gravel produced are not very good because they are more porous than natural aggregates, which represents a major obstacle. Indeed, they absorb too much water (between 5 and 10%) and slowly (for about twenty minutes). Thus, a concrete, which would be obtained with the sand and gravel produced by the process according to the invention and kneaded under usual conditions, would see its ability to be used drop significantly, during transport in a router, up to to make it unfit for use once it has reached its destination.
    On the other hand, when concrete is made, the cement reacts with water and forms hydrates of silica and calcium. It is these hydrates that give the mechanical strength of concrete. However, the hydrate molecules are not completely stable over time: in the presence of atmospheric CO2, they recarbonate naturally by slowly reabsorbing atmospheric CO2 and re-transform into limestone and silica gel.
    However, this natural chemical reaction, even slow (only 2 or 3 cm deep in concrete are recarbonated after 50 years), has always been feared by builders, because it makes concrete more acidic by lowering the pH (Hydrogen potential) and it leads to irreversible corrosion of the steel reinforcements which reinforce the reinforced concrete.
    To overcome these drawbacks, the recycling process comprises a step of rapid recarbonation of the 0.063 / 4 sand and 4/10 and 10/20 gravel obtained. For this, the latter must remain in contact, as long as possible, with the ambient air to capture and trap atmospheric CO2 in order, on the one hand, to limit the absorption of water which is harmful to the quality of concrete. and, on the other hand, to limit the drop in PH in concrete and therefore the corrosion of steels. This rapid recarbonation step consists of passing pressurized air into and under the 0.063 / 4 sand piles and 4/10 and 10/20 gravel obtained.
    In addition, the rapid recarbonation step also considerably improves the environmental impact of concrete obtained from recycled sand and gravel.
    The recycling process according to the invention makes it possible to produce 0.063 / 4 sand and 4/10 and 10/20 gravel making it possible to obtain a concrete having the same mechanical characteristics as concretes obtained with natural aggregates.
    To verify this, the applicant has carried out many long test campaigns in collaboration in particular with the Study and Research Center for the Concrete Industry (CERIB). These tests carried out over a period of one year made it possible to demonstrate that it was possible to make concretes, in particular of resistance class C25 / 30, with all or part of recycled aggregates. Two types of concrete were manufactured, a so-called mason concrete, the proportions of constituents of which are those given on the bags of cement, and a ready-to-use concrete (BPE) referring to standard NF EN 206.
    Thus, in the first case, the concrete produced, said mason's, incorporated 100% recycled aggregates (sand 0/4 and gravel 4/10). For this concrete, the use of recycled aggregates has led to a mixture with little workability, but with good compressive strength at 28 days.
    In the second scenario, the substitution of 30% of natural gravel by recycled 10/20 gravel (limit authorized by standard NF EN 206 for a type 1 recycled aggregate in exposure class XC1) has not had 5 of negative impact neither on the properties in the fresh state (under the temperature conditions of the test), nor on the compressive strength at 28 days.
    Possibility of industrial application
    The recycling process according to the invention applies more particularly to concretes resulting from the demolition of old works in order to obtain aggregates suitable for being integrated into new quality concretes, but it can also be used for the recycling of non-conforming concrete element with defects.
    Finally, it goes without saying that the examples of recycling process according to the invention which have just been described are only particular illustrations, in no way limiting of the invention.
    权利要求:
    Claims (8)
    [1" id="c-fr-0001]
    1 - Process for recycling concrete from the demolition or deconstruction of old structures to obtain aggregates suitable for integration into new quality concrete, characterized in that it comprises at least the following stages:
    - first crushing of demolition or deconstruction concrete to obtain 0/90 aggregate,
    - stripping of said 0/90 aggregate,
    - screening of said 0/90 aggregate to obtain a first 40/90 fraction and a second 0/40 fraction intended for use in road sub-layers,
    - second crushing in order to reduce the first fraction 40/90 into a new first fraction 0/25,
    - stripping of the new first fraction 0/25,
    - screening of the new first fraction 0/25 to extract the sand 0/4 from the latter and isolate the gravel 4/25,
    - extraction of particles smaller than 63 µm from sand 0/4, in order to recover only sand 0.063 / 4 which will finally be wrung out and piled up,
    - immersion of the 4/25 gravel to allow floating materials of the plastic and / or wood type to rise to the surface in order to be separated from said 4/25 gravel,
    - screening of 4/25 gravel in order to produce the following three cuts: 4/10 gravel, 10/20 gravel and 20/25 gravel, the latter being qualified as refusal,
    - rapid recarbonation of the sand 0.063 / 4 and gravel 4/10 and 10/20 obtained.
    [2" id="c-fr-0002]
    2 - Recycling method according to claim 1 characterized in that it comprises, before the first crushing, a visual inspection of demolition or deconstruction concrete, when they arrive at the recycling site.
    [3" id="c-fr-0003]
    3 - Recycling method according to any one of claims 1 or 2 characterized in that it comprises a pre-cleaning of demolition or deconstruction concrete before the first crushing.
    [4" id="c-fr-0004]
    4 - A recycling method according to any one of claims 1 to 3 characterized in that it comprises a blowing of the first fraction 40/90 stripped.
    [5" id="c-fr-0005]
    5 - Recycling method according to any one of the preceding claims, characterized in that the screening of the new first fraction 0/25 and gravel 4/25 are carried out under water.
    [6" id="c-fr-0006]
    6 - A recycling method according to any one of the preceding claims, characterized in that the immersion of the gravel 4/25 is carried out in a basin equipped with two shafts with blades rotating in opposite directions so as to set in motion the gravel 4 / 25.
    [7" id="c-fr-0007]
    7 - A recycling method according to any one of the preceding claims, characterized in that the rapid recarbonation of the sand 0.063 / 4 and gravel 4/10 and 10/20 consists in passing pressurized air into and under the piles of 0.063 / 4 sand and 4/10 and 10/20 gravel obtained.
    [8" id="c-fr-0008]
    8 - Recycling method according to any one of the preceding claims, characterized in that the particles smaller than 63 pm extracted from the sand 0/4 are sent with the waste water to a clarifier icateur, in which a flocculent agglomerates them to obtain a mud able to descend to the bottom of said clarifier then to be evacuated to a landfill.
    类似技术:
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    同族专利:
    公开号 | 公开日
    FR3081863B1|2020-07-10|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    JP3221908B2|1992-02-28|2001-10-22|住友大阪セメント株式会社|Method for producing recycled aggregate and recycled aggregate|
    WO2010110563A2|2009-03-23|2010-09-30|한국건설기술연구원|Method for manufacturing recycled aggregates using rapid carbonation reaction|EP3909735A1|2020-05-15|2021-11-17|Neustark AG|Method and apparatus for upgrading of concrete granulate by means of co2-treatment|
    WO2021254902A1|2020-06-16|2021-12-23|Fischer Hans Joerg|Method and plant for concrete preparation|
    法律状态:
    2019-02-15| PLFP| Fee payment|Year of fee payment: 2 |
    2019-12-06| PLSC| Publication of the preliminary search report|Effective date: 20191206 |
    2020-01-31| PLFP| Fee payment|Year of fee payment: 3 |
    2021-05-28| PLFP| Fee payment|Year of fee payment: 4 |
    2022-02-04| PLFP| Fee payment|Year of fee payment: 5 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1854740|2018-05-31|
    FR1854740A|FR3081863B1|2018-05-31|2018-05-31|PROCESS FOR RECYCLING DEMOLITION CONCRETE|FR1854740A| FR3081863B1|2018-05-31|2018-05-31|PROCESS FOR RECYCLING DEMOLITION CONCRETE|
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