JP6920830B2 - Treatment method for filling mortar and water-absorbent waste - Google Patents

Description

The present invention relates to a method for treating filling mortar and water-absorbent waste.

As a method of disposing of dismantled concrete or the like, there is a case where the waste is stored in a storage container or the like in advance, and then the storage container is filled with mortar and solidified. In this case, the filling mortar is required to have high fluidity so that the filling mortar to be added after the storage of the waste is sufficiently distributed to the gaps of the waste. In particular, when the above-mentioned waste is radioactive waste, in general, the radioactive waste cannot be prewetting, so that it has high water absorption, and in this case, the mortar discharge port is separated from the waste by a certain distance or more. Therefore, the filling mortar is required to have a particularly high self-filling property.

As such a filling mortar, for example, as the cement-based material described in Patent Document 1, in-water inseparable concrete for prepacked concrete in which the flow distance in water is lengthened by blending a specific thickener, etc., have been conventionally used. It is conceivable to use various known highly fluid cement-based materials.

Japanese Unexamined Patent Publication No. 2015-221730

However, the above-mentioned waste often has water absorption, and particularly when solidifying waste having a water absorption rate of a certain level or more with mortar, it is like the cement-based material disclosed in Patent Document 1. Even if a mortar with high fluidity is simply used, the water content in the mortar is absorbed by the waste during filling, which reduces the fluidity, and the water content in the mortar is absorbed after filling, so that the mortar is absorbed. It has been recognized that it is extremely difficult to stably and accurately provide a cured product obtained by solidifying mortar with a desired size and strength due to the subsidence of the interface.

In the present invention, even if the target waste solidified by the mortar is a waste having high water absorption, the fluidity of the filling mortar during filling is reduced due to the high water absorption, and after filling. To provide a filling mortar capable of stably forming a cured product having desired properties by avoiding subsidence of the mortar interface of the mortar, and a method for treating such water-absorbent waste. With the goal.

The present inventors make the cement material of the filling mortar contain a specific ratio of fine powder, contain a predetermined AE water reducing agent and a curing accelerator, and further optimize the water / powder ratio. As a result, it has been found that both a decrease in the fluidity of the filling mortar during filling and a subsidence of the mortar interface after filling can be avoided at the same time, and the present invention has been completed. Specifically, the present invention provides the following.

(1) A filling mortar in which a cement material, a fine aggregate, water, an AE water reducing agent, and a hardening accelerator are mixed, and the cement material has a specific surface area of 5000 cm ² / g. The above-mentioned fine powder ratio is 70% by mass or more, and the AE water reducing agent is a constituent unit derived from a water reducing component made of a polycarboxylic acid-based copolymer and a sulfo group-containing (meth) acrylic acid derivative. It is a cement additive containing a viscosity adjusting component made of a water-soluble polymer containing, and the AE water reducing agent is 0.01% by mass or more in terms of solid content in the filling mortar. The hardening accelerator is a calcium silicate hydrate having a particle size of less than 1000 nm, which is contained in an amount of 35% by mass or less, and the hardening accelerator is contained in the filling mortar in terms of solid content. A filling mortar containing 0.01% by mass or more and 0.7% by mass or less, and having a water / powder ratio of 45% or less.

According to the invention of (1), in the whole waste treatment of solidifying waste with mortar, even if the target waste is a waste having high water absorption, it is generated due to the high water absorption during filling. By avoiding a decrease in the fluidity of the filling mortar and the sinking of the mortar interface after filling, the waste can be stably treated as a desired cured product.

(2) The filling mortar according to (1), wherein the fine powder is silica fume cement.

In the invention of (2), silica fume cement was particularly used as the fine powder in the invention of (1). According to this, in the filling mortar of (1), a solid cement matrix and an appropriate viscosity are imparted to the filling mortar by the filler effect and the ball bearing effect of silica fume, and the occurrence of bleeding is more reliably prevented. Can be done. In addition, the stability of the cured state of the filling mortar can be further enhanced. In addition, high material separation resistance can be ensured.

(3) The filling mortar according to (1) or (2), wherein the cement material has a fly ash ratio of 5% by mass or more and 30% by mass or less.

In the invention of (3), the cement material in the invention of (1) or (2) was assumed to contain fly ash in a predetermined ratio. According to this, in the filling mortar of (1) or (2), the probability of cracking due to temperature stress can be further reduced.

(4) Prepacked concrete in which water-absorbent waste having a water absorption rate of 3.5% or more in an absolutely dry state is solidified by the filling mortar according to any one of (1) to (3).

In the invention of (4), even if the waste having a water absorption rate of a certain level or higher, which has been difficult to treat stably in the past, is the object to be treated, the water-absorbent waste is stably desired. It can be solidified and processed according to its properties.

(5) A method for treating water-absorbent waste having a water absorption rate of 3.5% or more in an absolutely dry state, the waste storage step of storing the water-absorbent waste in a storage container, and the water-absorbent waste. The filling mortar includes a mortar filling step of filling the voids of the storage container in which an object is stored with a filling mortar, and the filling mortar has a specific surface area of 5000 cm ² / g or more and a proportion of fine powder of 70. A water-absorbent waste containing a mixture of cement material having a mass% or more, fine aggregate, water, an AE water reducing agent, and a hardening accelerator, and having a water / powder ratio of 45% or less. Processing method.

According to the invention of (5), in the whole waste treatment in which the waste is solidified by mortar, even if the waste having a water absorption rate of a certain level or more, which has been difficult to be treated stably in the past, is the object to be treated. By increasing the proportion of fine powder in the cement material and using the AE water reducing agent and the curing accelerator in combination, the fluidity of the filling mortar during filling is reduced due to the high water absorption. By avoiding the sinking of the mortar interface after filling, the waste can be stably treated as a desired cured product.

(6) The AE water reducing agent comprises a water reducing component made of a polycarboxylic acid-based copolymer and a viscosity adjusting component made of a water-soluble polymer containing a structural unit derived from a sulfo group-containing (meth) acrylic acid derivative. The cement additive contained, the AE water reducing agent is contained in the filling mortar in an amount of 0.01% by mass or more and 0.35% by mass or less in terms of mass in terms of solid content, and the curing accelerator is contained. However, it contains calcium silicate hydrate having a particle size of less than 1000 nm, and the curing accelerator is contained in the filling mortar in an amount of 0.01% by mass or more and 0.7 by mass in terms of solid content. The method for treating water-absorbent waste according to (5), which is contained in an amount of% by mass or less.

According to the invention of (6), the water-absorbent waste can be more stably cured and treated with desired properties.

(7) The filling mortar is filled by discharging the filling mortar from above the storage container while maintaining the state in which the injection pipe used for the filling does not come into contact with the water-absorbent waste (5) or (6). The method for treating water-absorbent waste according to.

According to the invention of (7), even when it is difficult to insert the mortar injection tube into the filling space for some reason, the filling mortar has sufficiently high self-filling property (5). ) Or (6) can be fully enjoyed.

(8) The method for treating water-absorbent waste according to any one of (5) to (7), wherein the water-absorbent waste is radioactive waste.

According to the invention of (8), even when it is necessary to avoid inserting the injection pipe of the mortar into the filling space due to the fact that the water-absorbent waste is radioactive waste, the filling mortar is sufficient. By having a high self-filling property, the effects of the inventions (5) to (7) can be fully enjoyed.

According to the present invention, even if the target waste solidified by the mortar is a waste having high water absorption, the decrease in fluidity of the filling mortar during filling caused by the high water absorption and the decrease in fluidity of the filling mortar. It is possible to provide a filling mortar capable of stably producing a desired cured product of waste by avoiding subsidence of the mortar interface after filling, and a method for treating such water-absorbent waste. can.

It is explanatory drawing which shows typically one Embodiment of the treatment method of the water-absorbing waste which can be performed using the filling mortar of this invention.

Hereinafter, embodiments of the present invention will be described. The filling mortar of the present invention can be applied to all disposal methods for solidifying and treating waste, but is particularly preferable for treating highly water-absorbent waste in which stable solidification treatment has been difficult in the past. Can be used. Further, since the filling mortar of the present invention has extremely high self-filling property, it can be particularly preferably used for solidification and disposal treatment of radioactive waste.

<Mortar for filling>
Hereinafter, the filling mortar of the present invention (hereinafter, simply referred to as “filling mortar”) will be described in detail. The filling mortar is prepared by mixing a cement material, a fine aggregate, and water, as well as a predetermined AE water reducing agent and a curing accelerator, which will be described in detail below. In addition, the cement material shall contain fine powder in a proportion equal to or higher than a predetermined value. The fine powder that constitutes the cement material and the other fine powders that do not form the cement material are collectively referred to as "powder".

Further, a cured product produced through a step of pre-laying coarse aggregate in a mold or the like and then filling with mortar is generally referred to as "prepacked concrete", but in the present specification, the filling mortar of the present invention is used. A cured product obtained by solidifying water-absorbent waste in the same manner as described above is also referred to as "prepacked concrete". Further, the filling mortar of the present invention can be particularly preferably used when the water absorption rate of the water-absorbent waste constituting such "prepacked concrete" in an absolutely dry state is 3.5% or more.

[Cement material]
One of the characteristics of the cement material used for the filling mortar is that the ratio of fine powder in the cement material is higher than that of a general cement material. Specifically, in the cement material in a specific surface area of, 5000 cm ² / g or more in which the proportion of fine powder 70 mass% or more, preferably not more than 6000 cm ² / g or more 7000 cm ² / g. The specific surface area in the present specification means a value measured in accordance with JIS R 5201. By setting the ratio of the fine powder to 70% by mass or more, bleeding is sufficiently suppressed while ensuring self-filling property even in the method of post-adding filling mortar to a storage container containing waste. The dimensional stability of the solidified product can be ensured.

Specifically, silica fume can be preferably used as the above-mentioned fine powder. The silica fume may be in the as-collected state, or may be processed into powder or granules. Particularly preferably, it is silica fume for concrete specified by JIS A 6207, whereby the effect of fine powder with stable quality can be obtained. In addition, silica fume cement in which silica fume and cement are premixed can be more preferably used. According to this, the effect of reducing the number of material storage facilities can be expected due to the premixed product.

In addition, fly ash, blast furnace slag, fine limestone powder and the like can be added to the cement material, if necessary. In particular, fly ash is preferable in that cracking due to temperature stress of the solidified material after filling of the filling mortar can be reduced by adding the fly ash at a ratio of 5% by mass or more and 30% by mass or less in the cement material.

[Fine aggregate]
For fine aggregate, refer to the Concrete Standard Specification of the Civil Engineering Society, the Building Construction Standard Specification of the Japan Society of Architecture, or JIS A 5005 (crushed sand), JIS A 5011 (slag fine aggregate), and JIS A 5021 (recycled fine aggregate). The specified fine aggregate for concrete (for example, sand, crushed sand, slag fine aggregate, lightweight fine aggregate, recycled fine aggregate, etc.) can be used.

[Water / powder ratio]
The filling mortar has a water / powder ratio of 45% or less, preferably 20% or more and 40% or less. By setting the water / powder ratio to 45% or less, even in the construction method in which the filling mortar is post-added to the storage container or the like containing the waste, the filling property into the voids between the wastes is sufficiently ensured. , Settlement of the mortar interface after filling can also be suppressed.

[AE water reducing agent]
The AE water reducing agent used for the filling mortar is a viscosity adjusting component composed of a water reducing component composed of a polycarboxylic acid-based copolymer and a water-soluble polymer containing a structural unit derived from a sulfo group-containing (meth) acrylic acid derivative. A cement additive containing and is used. Further, this AE water reducing agent may further contain a bleeding reducing component composed of a sugar alcohol. As such an AE water reducing agent, for example, one having the same composition as the "concrete composition for tunnel lining" disclosed in Japanese Patent Application Laid-Open No. 2015-218874 can be used. The term "AE water reducing agent" in the present specification shall be broadly interpreted, and the "high-performance AE water reducing agent" which may be treated as a separate additive shall also be used as long as it satisfies the requirements of the present invention. It shall be included in.

The AE water reducing agent used for the filling mortar is more preferably a "high-performance AE water reducing agent". Here, the "high-performance AE water reducing agent" in the present specification means "a chemical admixture for concrete specified in JIS A 6204".

The polycarboxylic acid-based copolymer contained in the AE water reducing agent used for the filling mortar preferably contains a structural unit represented by the general formula (1).

（１）
（式（１）中、Ｒ１は、水素原子又はメチル基を表す。ＡＯは、同一又は異なって、炭素数２〜３のオキシアルキレン基を表す。ｍは、ＡＯで表されるオキシアルキレン基の平均付加モル数を表し、１〜３０の数である。）

(1)
(In the formula (1), R1 represents a hydrogen atom or a methyl group. AO represents the same or different oxyalkylene group having 2 to 3 carbon atoms. M represents an oxyalkylene group represented by AO. It represents the average number of added moles and is a number from 1 to 30.)

The water-soluble polymer contained in the AE water reducing agent used for the filling mortar contains a structural unit represented by the general formula (2) as a structural unit derived from a sulfo group-containing (meth) acrylic acid derivative. The mass average molecular weight is preferably 50,000 g / mol or more and 20,000,000 g / mol or less. The mass average molecular weight and the number average molecular weight can be measured by gel permeation chromatography (GPC) in terms of PEG.

（２）
（式（２）中、Ｒ１は水素又はメチル基、Ｒ２、Ｒ３、Ｒ４は、水素、炭素数１〜６の脂肪族炭化水素基、又は、メチル基で置換されていてもよいフェニル基であり、Ｍは、水素、ナトリウム、カリウム、カルシウム、マグネシウム、アンモニウム又は有機アンモニウムであり、ａは、１／２又は１である。）

(2)
(In the formula (2), R1 is a hydrogen or a methyl group, and R2, R3 and R4 are hydrogen, an aliphatic hydrocarbon group having 1 to 6 carbon atoms, or a phenyl group which may be substituted with a methyl group. , M is hydrogen, sodium, potassium, calcium, magnesium, ammonium or organic ammonium, and a is 1/2 or 1).

The content of this AE water reducing agent in the filling mortar is 0.01% by mass or more and 0.35% by mass or less in terms of solid content. By containing this AE water reducing agent in the filling mortar at the above ratio, even if the waste to be solidified is a water-absorbing waste having a water absorption rate of 3.5% or more in an absolute dry state, it can be filled. It is possible to avoid a decrease in the fluidity of the filling mortar inside.

[Curing accelerator]
Further, in the filling mortar, a curing accelerator is further used in combination with the above-mentioned AE water reducing agent. As this curing accelerator, an additive containing calcium silicate hydrate having a particle size of less than 1000 nm as a main solid component is used. As such an additive, for example, an additive having the same composition as the "curing accelerator" disclosed in Japanese Patent Application Laid-Open No. 2015-120630 can be used.

The curing accelerator used for the filling mortar may contain a dispersant and water in addition to calcium silicate hydrate. The content of calcium silicate hydrate in the curing accelerator is preferably 0.1% by mass or more and 75% by mass or less, more preferably 0.1% by mass or more and 50% by mass or less, and further preferably 0.1% by mass or more. It is 15% by mass or less. The content of the dispersant in the curing accelerator is preferably 0.1% by mass or more and 30% by mass or less, and more preferably 0.1% by mass or more and 10% by mass or less. The content of water in the curing accelerator is preferably 24% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 95% by mass or less, and further preferably 70% by mass or more and 95% by mass or less.

The above-mentioned calcium silicate hydrate contained in the curing accelerator used for the filling mortar is represented by the following formula (3). In the formula, 0.1 ≦ m ≦ 2 is preferable, and 0.66 ≦ m ≦ 1.8 is more preferable. Further, 0.6 ≦ n ≦ 6 is preferable, and 1.2 ≦ n ≦ 5.5 is more preferable.
(Formula) mCaO ・ SiO ₂・ nH ₂ O (3)

The particle size of the calcium silicate hydrate is preferably less than 1000 nm, more preferably less than 300 nm, still more preferably less than 200 nm. The particle size of calcium silicate hydrate can be measured by an analytical ultracentrifugation method.

Calcium silicate hydrates include, for example, foshag stone, finbrand stone, zonotrite, cat stone, monoclinic tbermori stone, 9 Å-tobamolite (riverside stone), 11 Å-tobamolite, 14 Å-tobamolite (prombiel stone), geni stone. , Metagenite, calcium chondrodite, affiliite, α-C2SH, dellite, jafe stone, Rosenhan stone, kirara stone, suorn stone. In particular, zonotrite, 9 Å-tobamolite (riverside stone), 11 Å-tobamolite, 14 Å-tobamolite (prombiel stone), geni stone, metagennite, affylite and jafe stone are preferable.

The curing accelerator may further contain a thickener polymer. The thickener polymer is selected from the group of polysaccharide derivatives and (co) polymers having a weight average molecular weight Mw of more than 500,000 g / mol, preferably more than 1,000,000 g / mol.

Examples of the polysaccharide derivative include alkyl cellulose such as methyl cellulose (MC), ethyl cellulose, propyl cellulose and methyl ethyl cellulose, hydroxyalkyl cellulose such as hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC) and hydroxyethyl hydroxypropyl cellulose, and methyl. Examples thereof include alkylhydroxyalkyl celluloses such as hydroxyethyl cellulose (MHEC), methyl hydroxypropyl cellulose (MHPC) and propyl hydroxypropyl cellulose. More preferred are methyl cellulose (MC), hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC) and ethyl hydroxyethyl cellulose (EHEC). Particularly preferred are methyl hydroxyethyl cellulose (MHEC) and methyl hydroxypropyl cellulose (MHPC). It may also be carboxymethyl cellulose (CMC). Further, it may be a nonionic starch ether derivative such as hydroxypropyl starch, hydroxyethyl starch and methyl hydroxypropyl starch. Further, polysaccharides produced by microorganisms such as welan gum and xanthan, and naturally occurring polysaccharides such as alginate, carrageenan and galactomannan may be used.

A (co) polymer having a weight average molecular weight Mw of more than 500,000 g / mol, preferably more than 1,000,000 g / mol is produced from, for example, a nonionic (meth) acrylamide monomer derivative and / or a sulfonic acid monomer derivative. be able to. Nonionic (meth) acrylamide monomer derivatives include acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N, N-dimethylacrylamide, N-ethylacrylamide, N, N-diethylacrylamide, and N-cyclohexylacrylamide. , N-benzylacrylamide, N, N-dimethylaminopropylacrylamide, N, N-dimethylaminoethylacrylamide and N-tert-butylacrylamide. Sulfonic acid monomer derivatives include styrene sulfonic acid, 2-acrylamide-2-methylpropane sulfonic acid, 2-methacrylamide-2 methyl propane sulfonic acid, 2-acrylamide butane sulfonic acid and 2-acrylamide-2,4,4-trimethyl. It can be selected from the group of pentan sulfonic acids. The thickener polymer preferably contains a structural unit derived from a nonionic (meth) acrylamide monomer derivative and / or a sulfonic acid monomer derivative in an amount of more than 50 mol%, more preferably more than 70 mol%. Other structural units are derived from, for example, monomers such as (meth) acrylic acid, esters of (meth) acrylic acid with C1-C10-alcohols, vinyl acetate, vinyl propionate and styrene.

The content of the thickening polymer in the curing accelerator is preferably 0.001% by mass or more and 10% by mass or less, and more preferably 0.001% by mass or more and 1% by mass or less.

The content of this curing accelerator in the filling mortar is 0.01% by mass or more and 0.7% by mass or less in terms of solid content. By containing this curing accelerator in the filling mortar at the above ratio, even if the waste to be solidified is a water-absorbent waste having a water absorption rate of 3.5% or more in an absolutely dry state, it can be filled. Later subsidence of the mortar interface can be avoided.

<Disposal method of water-absorbent waste>
The method for treating water-absorbent waste of the present invention (hereinafter, simply referred to as "method for treating water-absorbent waste") is, for example, after storing the water-absorbent waste 2 in the storage container 3 as shown in FIG. , By filling the filling mortar 1 so as to sufficiently fill the voids in which the water-absorbent waste 2 does not exist in the storage container 3, it is widely applied to the waste disposal treatment performed by solidifying these. This is a possible processing method.

The method for treating water-absorbent waste is a treatment method mainly for treating water-absorbent waste 2 having a water absorption rate of 3.5% or more in an absolutely dry state. When the water absorption rate of the water-absorbent waste 2 is 3.5% or more, the above-mentioned adverse effects before and after filling the mortar are likely to occur. By using the filling mortar 1 in combination with, the decrease in the fluidity of the mortar during filling and the subsidence of the interface of the solidified mortar after filling caused by the high water absorption of the water-absorbent waste 2. And can be avoided. As the filling mortar 1, the filling mortar of the present invention described in detail above can be particularly preferably used.

[Water-absorbent waste]
The method for treating water-absorbent waste is waste having a water absorption rate of 3.5% or more in an absolutely dry state (in the present specification, such waste is referred to as "water-absorbent waste". ) Is a particularly preferable processing target. However, it is not an indispensable constituent requirement of the method of the present invention that all the objects to be treated are "water-absorbent waste", and it is applied to the treatment of all waste including such "water-absorbent waste". be able to.

[Waste storage process]
In the method for treating water-absorbent waste, the water-absorbent waste 2 to be treated is stored in the storage container 3 in advance. Since the filling mortar 1 is to be added after that, the solidified product obtained by this is a cured product having an aspect similar to that of so-called prepacked concrete in the sense that the binder is added after the arrangement of the aggregate.

[Mortar filling process]
After storing the water-absorbent waste 2 in the storage container 3, a mortar filling step of filling the voids of the storage container 3 with the filling mortar 1 is performed.

Here, when low-level radioactive waste discharged from a nuclear power plant is spread in a storage container, the voids are filled with mortar and solidified, and the waste is treated, the injection pipe 4 and the waste are discarded due to the characteristics of the radioactive waste. It is required to keep objects out of contact. In addition, due to equipment reasons, it is often not possible to compact due to vibration or the like. In this case, the mortar used for the solidification treatment of such radioactive waste is required to have high self-filling property that does not require pumping or vibration.

On the other hand, since the filling mortar 1 is extremely excellent in self-filling property, the filling of the filling mortar 1 in the mortar filling step is performed by water-absorbing and discarding the injection pipe 4 used for filling as shown in FIG. It can be carried out in a mode of discharging from above the storage container 3 while maintaining the state of not contacting the object 2 (for example, separating the solidified surface by a necessary distance d). The filling of the mortar in this embodiment can be applied extremely preferably when the water-absorbent waste 2 is a radioactive waste.

The filling mortar of the present invention, which has high filling property, dimensional stability, and non-bleeding property in a narrow space, and a method for treating water-absorbent waste using the mortar can be used in addition to the above embodiments. It can be used in various places and applications in each field of construction performed using filling mortar. For example, rebar joints, for various prepacked concrete, repair / reinforcement of various structures, seams, backfilling of tunnels, under slabs of tracks, under bearings of bridges, fixing of machine pedestals, containment vessels for radioactive waste, It can be exemplified that it is used for a PC grout or the like that fills a gap between a PC steel material and a sheath can.

Hereinafter, the method for treating the filling mortar and the water-absorbent waste of the present invention will be described in detail with reference to examples. The present invention is not limited to the examples shown below.

In order to confirm the particular effect of the present invention, first, each material shown in Table 1 below (in Table 2, each material is indicated by a symbol in the symbol list) is used, and the compositions shown in Table 2 below are used. To produce four types of filling mortars. As Example 1, the filling mortar of the present invention which can be preferably used in the method for treating water-absorbent waste of the present invention was produced, and as Comparative Example 1, a conventionally known general mortar was used. Further, as Comparative Example 2, a mortar different from Example 1 was produced only in that it did not contain a curing accelerator, and as Comparative Example 3, Example 3 was also produced only in that it did not contain the AE water reducing agent (SP2) according to the present invention. Manufactured a different mortar. As Comparative Example 4, a mortar different from the example was produced only in that it did not contain silica fume cement (C2). As the AE water reducing agent, as shown in Table 1, a high-performance AE water reducing agent was used.

The above-mentioned AE water reducing agent (high-performance AE water reducing agent (SP2)) is highly water-soluble and contains a water reducing component composed of a polycarboxylic acid-based copolymer and a structural unit derived from a sulfo group-containing (meth) acrylic acid derivative. It is a cement additive containing a viscosity adjusting component composed of a molecule, and the same agent as the cement additive (comparative additive 8) disclosed in Examples of Japanese Patent Application Laid-Open No. 2015-218074 was used. The above-mentioned AE water reducing agent (high-performance AE water reducing agent (SP1)) is a known AE water reducing agent composed of a complex of a polycarboxylic acid ether compound and an oriented polymer, and is a viscosity adjusting component composed of a water-soluble polymer. Does not contain.

The above-mentioned curing accelerator (AD) is an additive containing calcium silicate hydrate having a particle size of 10 nm or more and less than 1000 nm. More specifically, the curing accelerator obtained by the following production method was used as an additive.
(Manufacturing method of curing accelerator)
In a reactor equipped with a heating device and a stirrer, 800 g of polyethylene glycol monophenyl ether having a number average molecular weight of 5000 g / mol, 140 g of polyethylene glycol monophenyl ether phosphate having an average of 4 to 5 polyethylene glycol units, and 58 g of paraformaldehyde. The mixture obtained by filling with and was heated to a temperature of 110 ° C., and 32 g of sulfuric acid was added to initiate polycondensation. The reaction mixture was stirred for 300 minutes, diluted with water and neutralized to obtain an aqueous polycondensate solution (hereinafter referred to as polymer A). The comb polymer is available from the commercially available Glenium ACE30 (BASF Italy S.p.A.) composed of polycarboxylate ether and water based on the monomers maleic acid, acrylic acid, vinyloxybutyl-polyethylene glycol-5800. ) Was used (hereinafter referred to as polymer B). The weight average molecular weight of polymer B measured by GPC was 40,000 g / mol, and the solid content was 45% by mass.
As Solution 1, an aqueous silicate compound solution consisting of 93.72 g of sodium metasilicate pentahydrate and 263.3 g of water was prepared. As the solution 2, an aqueous calcium compound solution consisting of 117.3 g of calcium nitrate and 108.11 g of water was prepared. As Solution 3, a polymer solution consisting of 20.64 g of Polymer A, 53.84 g of Polymer B, and 342.4 g of water was prepared.
Solution 1 and Solution 2 were added to Solution 3 at supply rates of 45 ml / h and 91.8 ml / h, respectively, to give a cure accelerator. The reaction temperature was room temperature.

The meanings of the abbreviations in Table 2 are as follows.
C: Indicates C1 or C2.
P: Indicates the value of powder amount C + FA.
W / P: Water powder ratio W / C: Water cement ratio The unit amount (kg / m ³ ) of SP1, SP2 and AD indicates the amount added in terms of solid content.

As can be seen from the compounding ratios in Table 2, the solid-converted content ratio of the AE water reducing agent (SP2) in the filling mortar was set to 0.05% by mass in Example 1 and Comparative Example 2.

As can be seen from the compounding ratios in Table 2, the solid conversion content ratio of the curing accelerator (AD) in the filling mortar was 0.30% by mass in Example 1 and Comparative Example 3.

The following tests were conducted to confirm the physical characteristics of the filling mortars of Examples and Comparative Examples.

(Flow test)
The flow of each filling mortar of Examples and Comparative Examples was measured by a test method according to JIS R5201. However, the tamping of 15 strokes was not performed, and the flow table was not used, and the flow at the time of pulling up 0 strokes was measured on a steel plate of 50 cm × 50 cm. The test conditions were carried out in an environment where the temperature was 20 ° C. and the humidity was 60%. The results are shown in Table 3. It should be noted that those having an "average value" of this numerical value of 320 (mm) or more were evaluated as preferable filling mortars that can be preferably used for the treatment of water-absorbent waste. The "average value" of the flow test results in Table 3 refers to the average value of the diameter at which the spread is considered to be maximum and the diameter in the direction perpendicular to the diameter.

(P funnel flow time test)
For each filling mortar of Examples and Comparative Examples, the P funnel flow time was measured by a test method according to JSCE-F521. As the test conditions, the test was conducted in an environment of a temperature of 20 ° C. and a humidity of 60%, and the test was performed twice per case, and the average value was used as the result. The results are shown in Table 3. It should be noted that those having this numerical value in the range of 18 seconds to 50 seconds were evaluated as preferable filling mortars that can be preferably used for the treatment of water-absorbent waste. Further, with respect to the filling mortar of Example 1, 30 minutes, 60 minutes, and 90 minutes after kneading were also subjected to the same test as the above test, and the P funnel flow time was measured for each. .. The results are shown in Table 4 below.

According to "2012 Japan Society of Civil Engineers Concrete Standard Specification (Construction), p.374-389", the quality of filling mortar for prepacked concrete is such that material separation is small and the required fluidity and strength are required. , Durability and crack resistance must be obtained, and the fluidity is standardized at 16 to 20 seconds in the test according to JSCE-F521. On the other hand, for high-strength filling mortars that use a high-performance water reducing agent and have a water-bonding material ratio of 40% or less, it is said that the standard is 25 to 50 seconds in the above test.

(Bleeding rate test)
The bleeding rate of each filling mortar of Examples and Comparative Examples was measured by a test method according to JSCE-F522. As the test conditions, the number of tests was set to 3, and the cells were cured in an environment with a temperature of 20 ° C. and a humidity of 60%, and measured after 3 hours. The results are shown in Table 3. Since the occurrence of bleeding means the occurrence of material separation, it was evaluated that a mortar having a value of 0.0 (%) or less is a preferable filling mortar that can be preferably used for disposal of water-absorbent waste. ..

(Filling rate test)
For each filling mortar of Examples and Comparative Examples, the "filling rate" was measured by the following method. In this test, a recycled concrete crusher run (concrete glass, air-dried state (air-dried state)) having a particle size of 40 mm to 60 mm and a water absorption rate in the range of 3.5% or more and 8.0% or less in an absolutely dry state was used. , The filling property of the water-absorbent substance in the voids was measured in a state where the inner glue was spread in a cube-shaped vinyl chloride container having a side of 1.6 m. Specifically, first, the volume of the void was calculated from the difference between the volume of the vinyl chloride container weighed in advance and the volume calculated from the density and weight of the recycled concrete crusher run. After that, each filling mortar is injected into the container from an injection tube installed at one place 10 cm away from the top surface of the container until the entire container is filled, and the mortar filled from the weight of the filled mortar and the unit volume mass of the mortar. The value obtained by calculating the volume of each filling mortar and calculating the ratio to the above-mentioned void volume as a percentage was defined as the "filling rate (%)" in this test of each filling mortar. The value calculated as a percentage of the volume of the vinyl chloride container weighed in advance and the volume calculated from the density and weight of the recycled concrete crusher run was defined as the "actual volume ratio". The results are shown in Table 3. It was evaluated that the mortar having a "filling rate" of 95% or more was a preferable filling mortar that could be preferably used for the treatment of water-absorbent waste. Further, regarding the recycled concrete crusher run (concrete glass), the above-mentioned "air-dried state (air-dried state)" is a state in which the concrete glass is dried in the air, and moisture does not adhere to the surface. , Refers to a state in which some water is contained in the void.

(Sinking amount test)
For each filling mortar of Examples and Comparative Examples, the "sinking amount" was measured by the following method. In this test, a recycled concrete crusher run (concrete mortar, air-dried state) having a particle size of 40 mm to 60 mm and a water absorption rate of 3.5% or more and 8.0% or less in an absolute dry state was used, and the inner diameter was 150 mm and the height was high. The amount of sedimentation on the surface of the hardened mortar in the presence of a water-absorbent substance was measured in a state of being spread in a cylindrical container having a diameter of 300 mm. Specifically, each filling mortar is injected into the container from an injection pipe installed at one location 10 cm away from the top surface of the container until the entire container is filled, and then the top end of the cylindrical container is horizontally placed. After smoothing, the container is sealed and cured for one day in a slightly larger container, demolded so that the cross section of the test piece is exposed at the age of one day, and it passes through the center of the test piece and is 2 in the vertical direction. I cut it in one. The height of the cut surface was measured at 11 points, and the value calculated from the difference between the average value and the height of the container was defined as the "sinking amount (mm)" in this test of each filling mortar. The value calculated as a percentage of the volume of the vinyl chloride container weighed in advance and the volume calculated from the density and weight of the recycled concrete crusher run was defined as the "actual volume ratio". The results are shown in Table 3. It was evaluated that the mortar having a "settlement amount" of 2.0 mm or less was a preferable filling mortar that could be preferably used for the treatment of water-absorbent waste.

Further, regarding the filling mortar of Comparative Example 1, the amount of subsidence when the recycled concrete crusher (concrete glass) spread in the container is prewetting to make the surface dry and saturated (surface dry state) is also described above. A test under the same conditions as the test was performed, and the amount of settlement was measured for each test. The results are shown in Table 5 below. From the results in Table 5, it can be seen that the present invention is particularly effective when the water-absorbent treated product, which cannot be subjected to the prewetting treatment for some reason, is treated. Regarding the recycled concrete crusher run (concrete glass), the above-mentioned "saturated surface dry state (surface dry state)" means that the voids inside the concrete glass are filled with water, but water is present on the surface. It refers to the state in which it does not adhere, and refers to the standard state in which water does not enter or exit when making concrete.

From the above results, the method for treating the filling mortar and the water-absorbent waste according to the present invention is caused by the high water absorption even if the target waste solidified by the mortar is a waste having a high water absorption. By avoiding the decrease in fluidity of the filling mortar during filling and the sinking of the mortar interface after filling, the waste can be stably obtained as a cured product having desired properties. It turns out that there is.

In addition, according to the present invention, in a filling mortar for prepacked concrete in which coarse aggregate is pre-laid and then filled with mortar, even when the time required for filling becomes long, or the injection pipe of the mortar is filled. Since it is difficult to insert the mortar into the space, it cannot be expected to secure the filling property by adjusting the injection pressure, and the required filling property has to depend on the characteristics of the mortar itself. It can also be seen that it is possible to provide a filling mortar that maintains fluidity and maintains an appropriate viscosity that does not cause material separation.

1 Filling mortar 2 Water-absorbent waste 3 Storage container 4 Injection pipe 10 Prepacked concrete

Claims (12)

A filling mortar for the treatment of water-absorbent waste.
With cement material
Fine aggregate and
water and,
AE water reducing agent and
A filling mortar in which a curing accelerator and a curing accelerator are mixed.
The water / powder ratio is 45% or less,
The cement material has a specific surface area of 5000 cm ² / g or more and a proportion of fine powder of 70% by mass or more.
The AE water reducing agent is a cement containing a water reducing component made of a polycarboxylic acid-based copolymer and a viscosity adjusting component made of a water-soluble polymer containing a structural unit derived from a sulfo group-containing (meth) acrylic acid derivative. The AE water reducing agent, which is an additive, is contained in the filling mortar in an amount of 0.01% by mass or more and 0.35% by mass or less in terms of solid content.
The curing accelerator contains calcium silicate hydrate having a particle size of less than 1000 nm as a main solid component, and the curing accelerator is 0 in the filling mortar in terms of mass relative to solid content. Contains 0.01% by mass or more and 0.7% by mass or less,
Mortar for filling. The P-funnel flow time according to the following P-funnel flow test is 19 seconds or less.
The filling mortar according to claim 1.
P funnel flow test: Measure in an environment with a temperature of 20 ° C. and a humidity of 60% according to JSCE-F521. The measurement is performed twice, and the average value of the two measured values is taken as the P funnel flow time. The filling mortar according to claim 1 or 2, wherein the fine powder is silica fume cement. The filling mortar according to any one of claims 1 to 3, wherein the cement material has a fly ash ratio of 5% by mass or more and 30% by mass or less. Mortar for radioactive waste treatment,
The filling mortar according to any one of claims 1 to 4. Prepacked concrete in which water-absorbent waste having a water absorption rate of 3.5% or more in an absolutely dry state is solidified by the filling mortar according to any one of claims 1 to 5. A method for treating water-absorbent waste in which the water absorption rate in an absolutely dry state is 3.5% or more.
A waste storage process for storing the water-absorbent waste in a storage container, and
It comprises a mortar filling step of filling the voids of the storage container in which the water-absorbent waste is stored with a filling mortar.
The filling mortar contains cement material having a specific surface area of 5000 cm ² / g or more and a ratio of fine powder of 70% by mass or more, fine aggregate, water, an AE water reducing agent, and a hardening accelerator. A method for treating water-absorbent waste, which is a mixture and has a water / powder ratio of 45% or less. The AE water reducing agent is a cement containing a water reducing component made of a polycarboxylic acid-based copolymer and a viscosity adjusting component made of a water-soluble polymer containing a structural unit derived from a sulfo group-containing (meth) acrylic acid derivative. The AE water reducing agent, which is an additive, is contained in the filling mortar in an amount of 0.01% by mass or more and 0.35% by mass or less in terms of solid content.
The curing accelerator contains calcium silicate hydrate having a particle size of less than 1000 nm as a main solid component, and the curing accelerator is 0 in the filling mortar in terms of mass relative to solid content. The method for treating water-absorbent waste according to claim 7, which contains 0.01% by mass or more and 0.7% by mass or less. The mortar filling step is performed without performing the prewetting treatment on the water-absorbent waste.
The method for treating water-absorbent waste according to claim 7 or 8. 7. How to treat water-absorbent waste. After discharging the filling mortar from above the storage container, the filling mortar is solidified without compaction by vibration.
The method for treating water-absorbent waste according to claim 10. The method for treating water-absorbent waste according to any one of claims 7 to 11, wherein the water-absorbent waste is radioactive waste.

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