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
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
  • C04B28/08—Slag cements
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/00034—Physico-chemical characteristics of the mixtures
  • C04B2111/00103—Self-compacting mixtures
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
  • C04B2111/00767—Uses not provided for elsewhere in C04B2111/00 for waste stabilisation purposes
• • 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
  • C04B2111/60—Flooring 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
  • 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 belongs to the field of the packaging of nuclear waste and, more particularly, to the field of packaging by immobilization of waste such as radioactive technological waste of low and medium activity in a cement matrix meeting the criteria of durability of confinement, with a view to their storage in a dedicated center.
• the present invention proposes a self-placing mortar formulation, its method of preparation and its use for confining radioactive technological waste in packages intended to be stored in a nuclear waste storage center.
• Short and medium-lived short-lived waste means waste having a level of radioactivity ranging from a few hundred Bq / g to 1 million Bq / g and this radioactivity is halved over a shorter period or equal to 31 years.
• This waste is essentially derived from the exploitation nuclear installations or dismantling of stationary installations such as laboratory glassware, piping, pumps, scrap metal and rubble.
• cementation is the oldest and most common process for packaging such waste.
• Various cement-based formulations have been exploited to either inject waste packages or prefabricate internal packaging envelopes for receiving such waste.
• grouts are formulations mainly made of water and cement
• mortars include, in addition to water and cement
• sand and concretes include, in addition to water, cement, sand and gravel.
• the patent application FR 2 763 584 proposes a confinement concrete mainly comprising siliceous sand of small particle size dispersion; a binder composed of a low tricalcium aluminate cement and very fine additives of smaller particle size than cement; water with a ratio (weight of water) / (weight of binder) of less than 0.4; gravel and admixtures favoring the deflocculation of the fine elements.
• International application WO 2009/053541 describes a mixture of rheology modifying adjuvants for self-placing concrete without filler. This mixture comprises at least one 1 increasing agent predominantly to the shear threshold of the concrete in the fluid state and at least one 2nd increasing viscosity modifier predominantly the viscosity of the concrete in the fluid state.
• the 1 agent is preferably a natural polysaccharide ether modified by the introduction of lateral grafts including hydrophobic, or a hydroxyalkyl guar ether modified by the introduction of lateral grafts particularly hydrophobic.
• the concrete formulation further comprises a Portland cement, a calcareous filler, a cohesion agent, siliceous or silico-calcareous granules, a superplasticizer and water, the E / C ratio being equal to 0, 6.
• a shrinkage problem which may be a pre-set shrinkage caused by the evaporation of part of the water contained in the mortar, a heat shrinkage, after setting, due to the return of the mortar to room temperature or else hydraulic shrinkage, after setting, due to a decrease in volume resulting from the hydration and hardening of the mortar.
• the inventors have therefore set themselves the goal of preparing a mortar formulation that eliminates these nuisances and exhibits containment properties that meet the requirements and needs at the same time:
• the nuclear operators who package and immobilize technological waste want a product that is simple to manufacture, flexible to use, of constant quality, insensitive to the temperatures of the injection site, which does not need to be subjected to a vibration. when it is used and which does not show segregation or bleeding.
• the mortar should be used to obtain a matrix based on hydraulic binder for immobilizing technological waste, having a very low diffusion with tritiated water and which is confining, insensitive to gamma irradiation, resistant to freeze-thaw cycles, insensitive to the alkali-reaction, not very diffusive to chloride ions and not very permeable to gases.
• the mortar supplier wishes to have a simple formulation to manufacture, simple to deliver, simple to inject, remaining homogeneous on the high heights (without dynamic segregation) and having high performances at a young age and a low total withdrawal.
• the inventors have achieved the goal and solved the technical problems presented above by implementing a particular formulation of mortar meeting the requirements and needs of nuclear operators, technology waste disposal and storage systems and suppliers of mortars.
• the present invention relates to a mortar composition
• a mortar composition comprising:
• composition according to the invention essentially comprises the 7 aforementioned elements and, advantageously, is constituted by these elements, ie the composition according to the invention does not include any other element than the 7 aforementioned elements.
• the composition according to the invention does not comprise granules or polymers.
• silica Si0 2 .
• the siliceous sand used is a non-reactive sand with alkali-silica.
• the siliceous sand is sand washed prior to its implementation, for example, a siliceous sand supplied and delivered washed so as to eliminate a maximum of impurities.
• the silica sand used is clay-free.
• the siliceous sand is advantageously used dry in order not to have any influence on the water dosage of the formulation. It may be silica sand supplied and delivered dry.
• the siliceous sand used in the context of the present invention is advantageously an uncrushed sand and this, to limit both the effects of active silica release with the binder and the abrasive effects of the mortar in the pipes of injection.
• siliceous sand used in the context of the present invention advantageously has a regular granular spindle in order not to interfere with the workability of the mortar.
• the size of the siliceous sand used in the formulation according to the invention is advantageously less than 6 mm, in particular less than 5 mm and, in particular, less than 4 mm. Therefore, the composition according to the invention does not include any element of the sand, gravel or granular type having a particle size (average grain size) greater than 6 mm.
• the siliceous sand used in the composition according to the invention is in the form of two siliceous sands of different particle sizes. Indeed, the inventors have tested different granulometries with different formulations to find the maximum compactness. These tests were carried out using laboratory mixers of 2.5 L and 25 L. The best compromise was found with 2 siliceous sands of different and complementary grain sizes.
• the siliceous sand used in the composition according to the invention is advantageously constituted:
• siliceous sand preferably natural, washed, dried and screened, which aggregates the dimensions are within the range of 0.63 mm to 3 mm, and
• the dimensions of the aggregates are in the range of 0.16 mm to 1.25 mm.
• silica sand implemented present granular time as defined in Table 1 below:
• Mineral addition is an important element in the composition of self-compacting concretes.
• the mineral addition chosen is a calcareous filler.
• a limestone filler is a dry, finely divided product derived from the cutting, sawing or working of natural limestone rocks in the lime, aggregates and ornamental stone industry.
• the calcareous filler used has a fineness ie a particle size similar to that of the cement used to limit the phenomena of temperature rise during setting, to ensure the holding of the cement matrix and, in fact, to prevent a dynamic segregation and settlement of the mortar fresh.
• the calcareous filler used in the context of the present invention has an average grain size of between 5 and 20 ⁇ , in particular between 10 and 15 ⁇ , and in particular of the order of 12 ⁇ (ie 12 ⁇ ⁇ 1 ⁇ ). More particularly, the calcareous filler used in the context of the present invention is a limestone filler resulting from a marble quarry. In their experiments, the inventors have been able to observe that such a mineral addition combined with the other constituents of the formulation has made it possible to obtain a mortar exhibiting good workability, absence of bleeding and an increase in the duration of workability.
• silica fume is also an additive widely used in the formulation of mortars and concretes. Its properties are recognized to improve the compactness and limit the permeability of concretes and mortars, and consequently improve the mechanical performance of concretes and hardened mortars.
• the silica fume used in the context of the present invention is derived from the filters of the silicon metal manufacturing process.
• this silica fume is a powder whose particle size is at least 2 times smaller, in particular at least 5 times smaller and, in particular, 10 times smaller than that of the cement used in the composition according to the invention. It is the finest element of this composition.
• the silica fume used in the context of the present invention is a densified silica fume which is distributed homogeneously during the kneading.
• Densified silica fume is, as a reminder, produced by treating an undensified silica fume to increase its bulk density to a maximum of between 400 and 720 kg / m 3 .
• the treatment usually used consists of polishing the smoke particles in a silo, resulting in an accumulation of surface charges.
• silica fume added to the other constituents of the composition according to the invention and their combination made it possible to obtain a mortar having a low porosity, high mechanical performance in the range of high performance concretes, low shrinkage and low oxygen permeability.
• the cement used is advantageously a ternary compound cement composed of clinker, blast furnace slags and fly ash.
• clinker is meant a mixture comprising one (or more) element (s) chosen from the group consisting of a limestone; a limestone with a CaO content of between 50 and 60%; a source of alumina such as ordinary bauxite or red bauxite; a clay and a sulphate source such as gypsum, calcium sulphate hemihydrate, plaster, natural anhydrite or sulphocalcic ash, said element (s) being crushed, homogenized and raised (s) at high temperature above 1200 ° C, especially above 1300 ° C, in particular of the order of 1450 ° C.
• about 1450 ° C is meant a temperature of 1450 ° C ⁇ 100 ° C, preferably a temperature of 1450 ° C ⁇ 50 ° C.
• the high temperature cooking step is called "clinkerization”.
• the cement used in the context of the present invention is a CEM V and consists of 20 to 64% clinker, 18 to 50% blast furnace slag and 18 to 50% fly ash. More particularly, the cement used in the context of the present invention is a CEM V / A and consists of 40 to 64% clinker, 18 to 30% blast furnace slag and 18 to 30% ash. flying.
• the cement used in the composition according to the present invention is a CEM V / A having a low heat of hydration
• the notions of "heat of hydration” and, more particularly, “low heat of hydration”, are defined in the standard NF EN 197-1 / A1 of December 2004 "Cement Composition, specifications and conformity criteria of common cements".
• the heat of hydration corresponds to the amount of heat developed by the hydration of a cement in a given time.
• the heat of hydration of low cements heat of hydration must not exceed the characteristic value of 270 J / g determined:
• LH Common cements with low heat of hydration are designated by the letters LH.
• CEM V / A LH cement that can be used in the context of the present invention, mention may be made of CLC 32.5 cement from CALCIA.
• composition according to the invention comprises, in addition to the constituents exposed above, two adjuvants which are:
• a viscosity agent intended for producing concrete and fluid / self-compacting mortars which increases the viscosity of the mortar and having, as a side effect, a plasticizing and water-reducing function to limit bleeding in the fresh state
• a water-reducing plasticizer intended for carrying out pumping over long distances, with, for a secondary effect, a set-retarding function for increasing the duration of use.
• Maintainability was also verified in a Marsh cone flow range (with a 12.5 mm nozzle) between 50 and 120 sec, up to 5 hours of age.
• the adjuvants retained as the viscosity agent and the water-reducing plasticizer are compatible with each other and with the other constituents of the mortar according to the present invention.
• a viscosity agent is a water-soluble product that increases its viscosity. Viscosity agents are composed of molecules of long chains of polymers that adhere to the periphery of water molecules and adsorb a part of them.
• the viscosity agent used in the context of the present invention is an aqueous solution based on modified polyalcohols. More particularly, it is a viscosity agent with water reducing plasticizing side effect for the production of fluid or self-placing mortars.
• a specific example of viscosity agent used in the context of the present invention mention may be made CHRYSO ® Plast V70.
• the water-reducing plasticizer used in the context of the present invention is a superplasticizer.
• superplasticizer is meant a synthetic polymer manufactured for the concrete industry. This adjuvant makes it possible to increase very significantly the workability of a concrete without adding water, or decrease the amount of water to increase the mechanical strength without changing the workability of the concrete. Superplasticizers can reduce water requirements by about 30 percent.
• the water-reducing plasticizer is advantageously an aqueous solution based on modified phosphonate. More particularly, it allows very long maintainability of workability and is suitable for long-distance pumping.
• usable water reducing plasticizer in the context of the present invention include the CHRYSO ® Fluid Optima 100.
• composition according to the present invention comprises water whose accuracy of dosage is preponderant for obtaining the confinement properties of the mortar according to the invention, more particularly as regards the porosity, the permeability to gas and the diffusion of tritiated water (the excess water creating voids after hydration of the cement).
• the systematic search for the lowest possible water dosage should not affect the workability of the mortar when fresh.
• the water has a function of transporting fine elements and admixtures during mixing for better hydration of the components and a uniformly distributed action of the adjuvants and, consequently, for a better homogeneity of the mortar.
• the mortar composition according to the invention consists of:
• the mortar composition consists of:
• the present invention relates to a process for preparing a mortar composition as defined above.
• This method comprises the steps of:
• step (b) adding to the kneaded mixture obtained in step (b) the viscosity agent in particular as previously defined;
• step (d) adding to the kneaded mixture obtained in step (d) the water-reducing plasticizer in particular as previously defined and
• the elements used are in the form of powder or in liquid form (water used in step (a)). These elements are advantageously added one after the other.
• the mixture of step (b) is obtained by mixing / kneading all these elements together using a worm gear mixer at a speed of between 20 and 26 rpm for the main arm and between 87 and 127 rpm for the secondary arm.
• This mixing / kneading can last between 30 sec and 10 min, in particular between 45 sec and 5 min and, in particular, of the order of 1 min (i.e. 1 min ⁇ 10 sec).
• step (c) of the process the viscosity agent is added.
• the mixture of step (d) is obtained by mixing / kneading all these elements together using a worm gear mixer at a speed of between 20 and 26 rpm for the main arm and between 87 and 127 rpm for the arm secondary.
• This mixing / kneading can last between 30 sec and 10 min, in particular between 45 sec and 5 min and, in particular, of the order of 1 min (ie 1 min ⁇ 10 sec).
• step (e) of the process the water-reducing plasticizer is added.
• the mixture of step (f) is obtained by mixing / kneading all these elements together using a worm gear mixer at a speed of between 20 and 26 rpm for the main arm and between 87 and 127 rpm for the secondary arm.
• This mixing / mixing can last between 60 sec and 15 min, in particular between 90 sec and 10 min and, in particular, of the order of 2 min (i.e. 2 min ⁇ 15 sec).
• the present invention further relates to the use of a mortar of a composition as defined above or capable of being prepared by the process as defined above, for confining waste.
• This waste is in particular short-lived and low-level waste as defined previously.
• fresh mortar is meant a mortar having a plasticity allowing such a coating or trapping.
• the concept of fresh mortar is opposed to that of a hardened mortar.
• the characteristics of the mortar according to the present invention make it possible not to implement any vibration during confinement. However, a slight vibration can be applied in the case where there is a risk of imprisonment of air bubbles in the waste package. In any case, this vibration should not exceed 10 sec to guard against any risk of exudation of the fresh mortar.
• the present invention also relates to a package of waste confined in a mortar of composition as defined above or likely to be prepared by the process as previously defined and packaged in drums or boxes including drums or metal or concrete boxes.
• the mortar of the invention forms a confining envelope surrounding the waste and in particular short-lived and low-level short-lived waste as previously defined.
• the production of the industrial batch was carried out in less than 15 minutes as follows:
• the characterization test was carried out from the industrial tool, namely, the mixer of the concrete batching plant designed to make one cubic meter of waste in the concrete industry.
• the mixer of the concrete batching plant designed to make one cubic meter of waste in the concrete industry.
• test specimens more than 80 test pieces (specimens 11 cm in diameter and 22 cm in height, hereinafter referred to as standard test specimens) were made to characterize from the same batch and by an accredited laboratory. the performance of the mortar according to the invention.
• the ability of the mortar to be injected is verified by measuring the passage time of one liter of mortar through the Marsh cone with 12.5 mm nozzle.
• the passage time should be in the range of 50 to 120 sec.
• the maneuverability measured at the Marsh cone was 92 sec and therefore was still in the desired range.
• HIGH PERFORMANCE thanks to its mechanical characteristics with a compressive strength greater than 50 M Pa at 28 days.
• the measurements of the compressive strength on an industrial batch carried out on standard specimens kept at room temperature under water, according to the standard NF EN 12390-3 (compressive strength of the test pieces) are 84.5 M Pa at 28 days and from 105.8 M Pa to 90 days.
• the manufacture of the mortar is also easily achievable from pre-dosed dry loads.
• the mortar is injectable within 5 hours after manufacture in both dry and wet form, at low and high temperatures and at the dosage tolerance limits.
• Density measured from standard specimens is 2.4 to 48 hours and 2.32 to 28 days
• the mortar has a shrinkage of 370 ⁇ / ⁇ measured according to standard NF P15-433 of February 1994.
• the apparent gas permeability is measured on standardized mortar specimens, stored in laboratory water, after drying at 105 ° C ⁇ 5 ° C to constant mass. A determined pressure gas percolates through the specimens, its flow rate is measured and the coefficient of permeability is determined based on the Poiseuille law. The coefficient thus obtained is 73.10 18 m 2 .
• the porosity accessible to water corresponds to the ratio of the void volumes accessible to water and the apparent volume of the mortar. It is measured by hydrostatic weighing on mortar samples kept in water in the laboratory (submerged saturated mass), on immersed saturated water-saturated mortar specimens (saturated mass) and on specimens dried at 105 ° C ⁇ 5 ° C up to constant mass (dry mass). The porosity accessible to the water thus obtained is 9.4%.
• This characteristic is particularly related to the use of sands unreactive alkali-reaction.
• the water diffusion coefficient tritiated is measured on standardized mortar test pieces, placed in a sealed manner, between a 1 containing water compartment tritiated and 2nd containing water initially not tritiated.
• the tritium activity detected in the 2 nd compartment is monitored as a function of time until the appearance of a constant material flow.
• the effective diffusion coefficient of tritiated water evaluated by application of Fick's law is less than 1.10 13 m 2 / s.
• the mortar according to the present invention was subjected to 8.10 Gray 5 under 300

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)

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• 2011
  • 2011-11-18 FR FR1160504A patent/FR2982856B1/fr active Active
• 2012
  • 2012-11-16 JP JP2014541677A patent/JP2014533645A/ja not_active Ceased
  • 2012-11-16 WO PCT/EP2012/072818 patent/WO2013072454A1/fr active Application Filing
  • 2012-11-16 EP EP12787728.0A patent/EP2780298A1/de not_active Withdrawn

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