FR2628255A1 - METHOD FOR FILLING CAVITIES - Google Patents

Abstract

The invention relates to a method for filling cavities, preferably reinforced concrete containers, with a concrete-like sealant. As a sealing agent, a concrete mixture is used which consists of clay flour and / or fly ash and aggregate as well as a quantity of a binding agent so minimal that the concrete retains its plastic character. , with the addition of an air or gas pore forming agent. The invention applies in particular to hazardous materials such as radioactive waste.

Description

The present invention relates to a method for filling cavities,

  advantageously of reinforced concrete containers by means of nuclear reagents which are sealed or enclosed therein or of hazardous waste, such as radioactive waste, by a sealing agent

resembling concrete.

  In the previously published unpublished patent application P 38 02 910.3, has been described the deposition of a nuclear power plant underground, where the nuclear power plant is sealed in a reinforced concrete container, which consists of

  of a cylindrical outer wall with a hemispherical dome

  and a circular disk seat plate. The cavities or hollow spaces that remain in the container are usefully filled with a sealant as has been described for example in DE PS 58 54 330. If a traditional concrete is used as a sealing agent,

  it expands due to the heat of hydration.

  If the concrete is used to encapsulate or seal the nuclear reagents or the radioactive waste, it results, from the decomposition of the radioactive material, of the additional heat, which stagnates in the container and leads to an additional dilation of the introduced concrete. as a sealing agent. But a traditional lean concrete expanding under the effect of heat exerts on the walls of cavities or hollow spaces or containers a pressure so important that the walls explode or that crevasses may form there. Such cracks in the walls of

  cavities can not be admitted especially when -

  hazardous materials, such as waste

  radioactive material, must be stored there.

  The present invention therefore has the task of providing a sealant resembling concrete, for use in a process of the type indicated above, which does not exert pressure against the walls of the hollow space or cavity, because of the effect of heat, a magnitude that can lead to an explosion of walls or the formation of crevices. According to the invention, this task is solved in the case of a process of the above type described by the fact that the use as a sealing agent of a mixture of concrete with soil consistency, consisting of flour of clay and / or fly ash and aggregate and such a small amount of a binding agent that the concrete retains its plastic character with the addition of a

  agent forming pores of air or gas.

  Concrete mixtures with soil consistency consisting of cement, aggregate and clay flour with a

  very low modulus of elasticity and high deformation

  have been used for a long time for sealing purposes. Such mixtures are increasingly taking on the character of an earth consistent with the increase in cement content compared to clay flour. As a binding agent, fly ash can also be used. Fly ash decomposes by giving off calcium oxide or calcium hydrate respectively. As the curing process goes on for a long time, the strength properties of a mixture of earth cement with fly ash extend over a long time,

  which would be inconvenient for the process according to the invention.

  According to one characteristic of the invention, inert concrete ash, that is to say fly ash without hydraulic properties, is added to the earth-consistency concrete mixture. Calcium oxide is added in a minor amount in proportion to the fly ash. For example, a small amount of blast furnace cement is added with a large proportion of slag, so that only a portion of

  Fly ash may react with lime hydrate.

  If the proportion of lime is exhausted, the reaction stops. The strength of the mixture remains low, while the high proportion of fly ash increases the tightness of the mixture. Another advantage of the mixture lies in the fact that only a heat results

minimal hydration.

  Another improvement of the deformability, with the compressive strength and the bending and sealing remaining simultaneously at the same high level of the earth-consistency concrete, is obtained when are produced in the mixture, by air pore formers, micropores of air in an amount of 3 to 10% by volume, by intensive mixing. These micropores of air resembling cells or cells are not destroyed, even by relatively high pressures. Even in the case of a full water saturation of the grain adjuvant, their volume decreases, during compression, from

  so that the bodies can expand in the pores.

  By the addition of an air pore forming agent (LP agent), the viscous part of viscoelastic behavior

  concrete that looks like the earth is raised.

  The concrete mixture used according to the invention is particularly suitable as a sealing agent in reinforced concrete containers with relatively rigid walls or also in cavities in the rock where radioactive waste is stored. Concrete includes radioactive waste, and the entire cavity is filled. Even when the concrete, due to the heat of hydration and the radioactive disintegration of the stored product, expands, because of its low modulus of elasticity and high viscoelasticity, it does not produce sufficient pressure on the material. the walls so that crevasses are to be feared. The concrete according to the present invention can be used particularly advantageous for sealing in the case of dams and

  any sealing layer in the soil.

  The concrete according to the invention contains a sufficiently large compression space, without the water must be expressed and without unreliable pressure exerted on the walls surrounding it, when it is used as concrete skinny. Due to its good viscoelastic properties, the concrete according to the invention retains, even in the compressed state, its good resistance properties. It has a good sealing effect

  and good stability in its compressed state.

  The concrete mixtures used according to the invention may, for example, have the following compositions: 1. 20 kg HOZ 35 L: 35 L blast furnace cement (slow-setting blast furnace cement with a strength of at least N / mm 2 ) 200 kg of fly ash kg of crushed clay 1300 kg of aggregate 0/16 sand-gravel mixture 350 kg of water 0.2 kg of LPS air pore former, Société GrUnau (foaming soap products) ) This mixture gives a concrete with the following properties: Permeability correction factor: k = 12 x 10 11 m / s Pore content: 5.8% by volume Compression modulus: K = 30 MN / m2 Modulus of elasticity : = 55 MN / m2 At the same time; uiwmosuoo s.dv eauma uo9.q and enb.e.ga1, nb; ue; ee: rd epuLei snld and eanb eJaTuwm ep 'wnToIeo ep apXxoI OeAm JDJ 0o essTnd his play se seo ueio se seo sep aeTd aun elnes enb uo5 $; ep 'eS1uitoA seJpueo ep uoTVSvTn, T ep seo T SUWp eTsToqo Zsae uewTo ep no xnrqo ep 4.d ml AAPTIoS sdjoo a 4UeTAap Ze sepTnbT ST, s. With his feet, he has been able to take care of his feet, and he has been able to do so in the past.

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Claims (3)

CLAIMS CATIONS   A method for filling cavities, advantageously reinforced concrete containers, with nuclear reagents enclosed therein or other hazardous waste, such as radioactive waste, with a sealant resembling concrete, characterized in that a mixture of concrete consisting of clay meal and / or fly ash and aggregate material and a binding agent in an amount as small as the plastic character of the concrete is preserved, with the addition of a   agent forming pores of air or gas.   2. Method according to claim 1, characterized in that one uses, as binding agent cement or lime.   3. Method according to one of the claims   previous, characterized in that in the use of fly ash, the proportion of lime or cement is kept so small that only a portion of the ashes   Inert flying can react with calcium oxide.