JPS59174556A - Non-shrinkage hydraulic cement composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic cement composition containing an alkali borosilicate or the like as a binder component. The present invention relates to a hydraulic cement composition suitable for producing a cured molded product having excellent water permeability, weather resistance, seawater resistance, acid resistance, and mechanical strength. In particular, the present invention relates to a hydraulic cement composition suitable for solidifying waste containing anhydrous, mirabilite, anhydrous borates, etc., which are by-products during the treatment of nuclear reactor wastewater.

Conventionally, hydraulic cements such as Portland cement have been widely used as cement compositions, but in such known hydraulic cements, 26 to 35 % of water is required.

However, it is well known that the mechanical strength and density of hydraulic cement are closely related to the amount of water mixed in, and conventional Portland cement has a relatively large amount of water mixed in. has the drawbacks of relatively low bending strength and relatively high water permeability. Furthermore, known uncured aqueous portland cement compositions have a problem of poor fluidity despite having a large amount of water mixed in, making it difficult to fill minute voids with the composition, for example.

Conventionally, dried concentrated waste liquid from around a nuclear reactor or ion exchange resin used for waste liquid treatment is filled into a container in a state in which it is hardened with a solidifying agent, and this sealed container is stored or disposed of. However, the anabolic agent used for this purpose must satisfy the various safety requirements described below. First, since this assimilating agent is exposed to radiation, it must not be significantly degraded by radiation, and from this point of view, an inorganic assimilating agent is desired. Also,
This solidifying agent must have excellent water penetration resistance, mechanical strength, and weather resistance. Furthermore, this solidifying agent must have a pot life long enough for operations such as filling, and must also have fluidity so that it can uniformly flow and fill any part of the container. Furthermore, it is also important to increase the waste volume relative to the container volume, ie the volume reduction ratio, and for this purpose the assimilation agent must be used in as small a volume as possible.

On the other hand, a composition comprising an alkali borosilicate and a curing agent such as an inorganic phosphoric acid curing agent as an inorganic binder has already been proposed (Japanese Patent Publication No. 57-42581), and this composition can prevent early gelation. Although stabilized against partial gelation and known to have a fairly long pot life, the use of this binder composition in the above-mentioned applications as an anabolic agent may result in certain disadvantages. Admitted. That is,
This composition has the disadvantage that it tends to produce syneresis water and shrink when cured, and furthermore, if the waste to be filled contains salts such as anhydrous sodium sulfate, which is a by-product of the ion exchange treatment of wastewater. The drawback is that this anhydrous sodium sulfate dissolves in syneresis water, and this solution recrystallizes into hydrated salt, resulting in volumetric expansion, which causes cracks, etc., to occur in the hardened cement composition. occurs.

Therefore, an object of the present invention is to prevent shrinkage during curing accompanied by the generation of syneresis water in a hydraulic cement composition containing a main binding component such as an alkali borosilicate and a curing agent. .

Another object of the present invention is to provide a cured product with excellent fluidity during filling and non-shrinkage during curing, as well as excellent water permeability, weather resistance, seawater resistance, acid resistance, and mechanical strength of the cured product. The present invention provides a hydraulic cement composition.

Still another object of the present invention is to provide a hydraulic cement composition useful as a solidifying agent for solidifying solid waste containing anhydrous sodium sulfate, anhydrous borate, etc. during the treatment of nuclear reactor wastewater. .

According to the present invention, (A) a water-soluble alkali borosilicate or a combination of a water-soluble alkali silicate and an alkali borate soluble in an alkaline bath liquid, (B) an acidic curing agent for the alkali borosilicate, and <C) A hydraulic cement composition is provided that is characterized by containing a water retention agent mainly consisting of an anionic surfactant.

The combination of (1) water-soluble alkali borosilicate or (III water-soluble alkali silicate and alkali borate soluble in an aqueous alkali solution) used as the first component (A) in the present invention is a conventional alkali silicate binder. In addition to,
It has a chemical composition characteristic of containing boric acid, and related to this characteristic, it can be used even under severe dehydration conditions and maintains a starch syrup-like state. Karen [I! It has 1′q property. Because of this property, the first component (A), when used in combination with the acidic curing agent (B), also provides the cement composition with excellent binding action and a moderate pot life, while also providing an aqueous When used as a dispersion, the desired effect is that the composition remains highly fluid without premature or partial gelation.

Furthermore, this hydraulic cement composition has the advantage of having excellent fluidity despite having a significantly small amount of mixed water, but has the disadvantage of producing syneresis water and shrinkage upon hardening. If such syneresis water is produced, not only will the appearance of the hardened solidified product be poor, but if the object to be solidified is anhydrous soluble salts such as anhydrous sodium sulfate, this salt will dissolve in the syneresis water. This causes problems such as stress concentration and cracks in the hardened solidified product due to volumetric expansion caused by recrystallization into hydrated salt.

A notable feature of the hydraulic cement composition of the present invention is that it contains a water retention agent mainly consisting of an anionic surfactant. Conventionally, it is well known that anionic surfactants are used as water reducing agents for Portland cement and the like. This water reducing agent is intended to reduce the amount of water mixed into Portland cement as much as possible and to improve the fluidity of cement slurry.

In contrast, in the present invention, the anionic surfactant is used as a water retention agent for hydraulic cement containing a binding component such as an alkali borosilicate and an acidic curing agent, that is, to prevent the generation of syneresis water during curing. It is used as a water retention agent to suppress and prevent its shrinkage.

That is, hydraulic cements made of a combination of an alkali borosilicate binder and an acid curing agent vary depending on their composition and the amount of water mixed, but generally speaking, the content is 1.0 to 4% before and after curing. or a weight loss due to syneresis water of 1.0 to 10% by weight based on the total weight. This generation or contraction of syneresis water is thought to be due to the fact that the water used for dispersing each component no longer adapts to the tissue or structure of the cured product and is discharged out of the system.

In order to prevent syneresis water from occurring, it may be possible to reduce the amount of mixed water below a certain level, but in this case, the necessary fluidity (fillability, moldability) may not be obtained, and the hardening This causes the problem that the strength of the body etc. decreases.

According to the present invention, by incorporating an anionic surfactant into the composition, the generation of syneresis water is suppressed to substantially zero, and the present inventors have explained the reason for this. It is estimated as follows. That is, it is known that when granulating silica gel, an anionic surfactant acts as a binder or strength improver. In the composition of the present invention, it is thought that a network structure of borosilicate, that is, a gel, is formed during curing, but the anionic surfactant added to the system causes moisture to form in this gel structure. It is presumed that this acts to stably hold the water as structured water and homogenize the tissue. This estimation agrees well with the fact that the composition of the present invention not only has excellent shrinkage resistance (water syneresis resistance) but also excellent water permeation resistance.

In the present invention, the first component (A) can be a combination of powdered alkali silicate and powdered alkali borate. This powdered alkali silicate is water-soluble or water-dispersible, and has a molar ratio of MtO: 5sOt (wherein M represents an alkali metal) of 1:1.3 to 1:3. Those having a molar ratio of 2 are preferred. When the molar ratio of alkali is outside the above range 4, adhesive strength etc. tend to decrease when used as a binder. Sodium silicate is preferred for the purposes of the present invention, but potassium silicate can also be used. The alkali silicate used in the present invention may contain water or the like as long as it is in the form of a powder.

As the alkali borate salt, any salt can be used as long as it is soluble in an alkaline aqueous solution, and for example, sodium borate and potassium borate are preferably used. These borates may be anhydrous salts or hydrated salts such as hexahydrate, pentahydrate, heptahydrate, and decahydrate.

The alkali silicate and alkali borate have a molar ratio of 31030 in the alkali borate to Sing in the alkali silicate from 1:0.03 to 1:0.3, particularly 1:0.05.
It is preferable to use a combination in the range of 1:0.25.

Instead of using the alkali silicate and alkali borate as a powder mixture, they can also be used in the form of an aqueous aqueous solution of the alkali borosilicate. That is, this aqueous solution is
It can be obtained by dissolving two salts in water and carrying out a heating reaction if desired. Alternatively, by adding alkali borate or alkali borate and alkali to a commercially available water glass solution,
It can also be produced by heating a solution.

However, when the molar ratio of boric acids (BIOs) is smaller than the above range, water resistance and stability tend to decrease, whereas even if it is larger than the above range, there is no particular advantage. This is economically disadvantageous.

The acidic curing agent used as the second component CE) includes silicofluorides such as sodium silicofluoride, potassium silicofluoride, calcium silicofluoride, and aluminum silicofluoride; silicon polyphosphate, alkali metal salts of silicon polyphosphate, and titanium phosphate. , phosphates such as zirconium phosphate, aluminum phosphate, zinc phosphate: other acid salts such as aluminum 5A acid, aluminum nitrate, aluminum chloride, and various borates. All of these acidic curing agents exhibit an acidic pH when added to water, and act as a curing agent for the first component (A).

Among these acidic curing agents (B), in the present invention, it is desirable to use a silicofluoride, especially an alkali silicofluoride. In other words, the alkali fluorosilicide has the function of a hardening agent, but a composition containing this hardening agent has the advantage of being excellent in water wettability and fluidity in a slurry state. give. When this alkali fluorosilicide is used as a curing agent in combination with a small amount of silicon polyphosphate, the best results can be obtained in terms of various physical properties of the cured product.

In the present invention, a water retention agent mainly composed of an anionic surfactant is used as the sixth component (C). Examples of anionic surfactants include lignin sulfonate, alkylnaphthalene sulfonate, alkylbenzene sulfonate,
Naphthalene sulfonate formalin condensate and the like are preferably used. A cationic surfactant cannot provide the shrinkage preventing effect as in the present invention. A suitable water retention agent is a formaldehyde high condensate of naphthalene sulfonic acid, and the salts used include potassium salts, sodium salts, umium salts, ammonium salts, amine salts, calcium salts, and the like.

As the water retention agent (C), anionic surfactants can be used alone or in combination with zeolite. When zeolite is used in combination, an auxiliary effect or a synergistic effect is observed in preventing the occurrence of syneresis, and water resistance is further significantly improved. Zeolites include clinoptilolite, erionite,
Mordenite, Chabazite Jlp natural zeolite J
Synthetic zeolites such as PA type, X type, Y type or 7'' type are preferably used.

In the present invention, based on the solid content, binder component (A) such as alkali borosilicate, per 100-type needle,
50 to 100 parts by weight, especially 60 to 75 parts by weight of an acidic curing agent CB), and 0.1 to 20 parts by weight, especially 1 to 5 parts by weight, of an anionic surfactant (C) as a water retention agent. Good to use.

That is, if the amount of the acidic curing agent is less than the above range, the composition tends to solidify and the strength and water resistance of the cured product tend to decrease, while if the amount exceeds the above range, the composition tends to harden. There is a tendency for the pot life to decrease, the pot life to become short, and the compactness of the cured product to be lost, resulting in a decrease in the properties of the cured product.

Also, if the amount of water retention agent (,C) is less than the above range,
The effects of preventing syneresis water generation and shrinkage will be inferior to those within the above range, while on the other hand, if the amount exceeds the above range, the fluidity of the slurry will decrease and the water resistance of the cured product J
There is a tendency for P mechanical properties to decrease.

Zeolite as a water retention aid is a binder component (A
) It is preferred to use 2 to 7 parts by weight, especially 3 to 5 parts by weight of leaves per 100 parts by weight.

The hydraulic cement composition of the present invention may contain various additives or auxiliaries in addition to the above-mentioned essential components.

For example, it is desirable to incorporate fly ash into this composition. In other words, when an anionic surfactant is added as a water retention agent, the compressive strength of the cured molded product tends to decrease slightly, but by adding fly ash, this decrease in compressive strength is prevented, and furthermore, syneresis Supplementary effects are observed in preventing water generation and improving water permeability, as well as improving seawater resistance. Fly ash is minute ash particles collected by a gin collector from a pulverized coal combustion boiler, and is generally a spherical particle with an ash content of 45% or more of silica, and 75% or more of it passes through a 44μ sieve. It is something. This fly ash is preferably used in an amount of 2 to 60 parts by weight, particularly 5 to 25 parts by weight, per 100 parts by weight of the binder component (A).

From the viewpoint of flow characteristics, it is desirable to incorporate crystalline barium metasilicate powder into the hydraulic cement composition of the present invention. That is, by blending crystalline barium metasilicate, the fluidity of the aqueous slurry before hardening is significantly improved. It also penetrates into the microscopic spaces between all the particles, making it possible to form solid assimilated bodies. Crystalline barium metasilicate, generally having a water-soluble content of 0.5 to 60% by weight, is suitable for this purpose. Component CE) is component (A)
It is preferable to use 0.1 to 20 parts by weight, particularly 1 to 5 parts by weight, per 0 parts by weight of the compound.

As a reinforcing agent, use fibrous reinforcing agents such as glass fiber, rock wool, slag wool, asbestos, talc, carbon fiber, gold) IA woven fiber stable, sliver, mat, woven non-woven fabric or net. In addition, fine Vy powder 1111 strength agents such as carbon black, glass powder, white carbon, silica sand powder, and various bright metal powders can be used. In addition, as a filling oil,
Kaolin, Akatsuki Rei, acid clay, activated clay, silicon dioxide, aluminosilicon 1i12 and its salts, titanium dioxide, zirconium dioxide, alumina powder, barium sulfate,
Magnesium carbonate, magnesium oxide, calcium carbonate, calcium silicate, zinc oxide, gypsum, zeolite powder,
Inorganic fillers and aggregates such as sand, rock, and refractory minerals are used. However, water-based cement powders such as Portland cement powder, alumina cement powder, etc. can also be used to strengthen the cement composition of the present invention and to appropriately adjust the water content. Furthermore, various organic fillers such as phenol resin, urea resin, CMC, etc. can be mixed and used in the form of powder or liquid.

In addition to white pigments such as titanium dioxide, colored pigments such as yellow lead, red iron, ultramarine, chrome green, mars violet, carbon black, and red iron are used as pigments.

Various acidic, neutral, or basic refractory aggregates are used depending on the purpose, such as chamotte, waxite, mullite, semisiliceous high alumina (perlite), etc.
AlvOs SiOx aggregates such as;
i02 type aggregate; A/lOs type aggregate such as corundum and other fused alumina; MgO-8i such as holsterite
O7-based aggregate; silicon carbide (SiC-based): pyrolead nichrome,
Magnesium chromium, magnesium chromium; magnesia clinker 1 Magnesium fused magnesia, calcined dolomite, magnesia, karja, etc. may be used alone or in combination of two or more.

These aggregates are subjected to particle size adjustment which is known per se. Generally, the coarse particles with a particle size of 1 to 5 mm are 10 to 70% by weight, and the fine particles with a particle size of less than 1 mm are 90 to 60% by weight. A refractory composition is prepared by blending them in such proportions as follows. Of course,
These aggregates can also be directly pulverized to a particle size close to the above particle size structure and used as aggregates without sieving or the like.

Furthermore, various thickeners, latexes, various thickeners, etc. may be added to temporarily enhance the tackiness of the initial aqueous dispersion.

Of course, the types and amounts of the above-mentioned compounding agents must be selected so as not to impair the workability of the final composition.

The hydraulic cement composition of the present invention can be used as a two-package curing composition in which the curing agent component and the binder component are packaged separately, or as a one-package curing composition in which all the components are mixed together.
It can be used for various purposes as a packaged cured composition.

The cement composition of the present invention can be used in the production of various molded articles. For example, the i-ment composition of the present invention may contain a fibrous or finely powdered reinforcing material or filler,
Furthermore, in combination with aggregate, it can be used to create various combustible molded structures, such as roofing materials, interior and exterior tiles, blocks, bricks, hollow wall members, floor members, partition members, soundproofing materials, fireproof coatings for steel materials in high-rise buildings, etc. Building materials: Furniture such as tables and chairs; Tableware and other containers; Various decorative items; Eight structural materials such as pipes, sheets, blocks, beams, columns, and casings; Various casting molds; Fixed or irregular shapes Bricks for the ceramic industry; Useful as a binder, adhesive, solidifying agent, cement agent, filler agent, and inder for the treatment of industrial waste, especially radioactive PA waste.

The cement composition of the present invention can also be used as an adhesive for manufacturing aggregates or sacrificial structures by bonding glass, bricks, slate, blocks, various fish industry products such as tow porcelain, scrap metal, etc. It is also useful for applications such as

Furthermore, the cement composition of the present invention can be applied to bricks, towware, concrete products, gypsum boards, wood, paper, and other fibers.
It is useful for imparting properties such as non-combustibility or water impermeability to these materials, and is also useful for forming non-combustible coatings. It is useful for

Furthermore, the cement composition of the present invention can be made into an inorganic paint by adding fillers or pigments as necessary, and applied to various structures as a heat-resistant paint.

When producing solidified molded products, adhesive structures, and coated structures using the composition of the present invention, the aqueous dispersion can be cured under normal conditions or under heat and pressure. For example, the curing temperature is 10 to 200°C, especially 10
The temperature may be in the range of 150° C. to 150° C., and the pressure during curing may be normal pressure or under pressure of up to about 10 kg/am 2 . In addition, the atmosphere during curing is usually air, but if desired, it can be under reduced pressure or an inert atmosphere such as a nitrogen gas atmosphere, and carbon dioxide gas can be used as the atmosphere to further shorten the curing time. may also be used.

Furthermore, by keeping the curing atmosphere at a high humidity condition, for example, 60%, preferably 80% or higher, it is possible to homogeneously harden the inside and surface of the cured product, making it possible to harden the molded product uniformly. Strength and other physical properties can be improved.

The required curing time varies depending on the temperature, curing agent, and type and amount of auxiliary agents, but generally speaking, choose an appropriate time depending on the curing temperature used from 2 minutes to 1 week. Good. For example, in the case of heat curing of a coating composition, sufficient curing can be achieved in about 2 to 10 minutes, and in the case of room temperature curing of adhesive structures and thick moldings, complete mechanical strength can be achieved. It may take about one week to obtain a cured product having the following properties.

Since the cement composition of the present invention has the various properties described above, it is suitable for use in radioactive waste I￥j such as anhydrous mirabilite or anhydrous borium.
Various advantages are achieved when dry salt-containing wastewater is used as a solidifying agent. First, the hydraulic cement composition of the present invention can be cured with an extremely small amount of water mixed in, and the cured product has excellent mechanical strength in various ways, compared to conventional hydraulic cements. It is possible to solidify radioactive waste using a very small amount, and as a result, the waste can be filled into a container such as a drum can and solidified at a high volume reduction ratio. In addition, the aqueous cement composition for hardening has excellent fluidity despite the small amount of water mixed in, and when the waste granules are filled in a container and then mixed, It also has the effect of reaching every corner of the container, coating them, and solidifying them together. Furthermore, this assimilating agent has excellent density, water permeability, and shrinkage resistance after curing, so even if it comes into contact with moisture, direct contact between waste and water is prevented. First, it can prevent the anhydrous salt contained in the waste etc. from absorbing water and crystallizing it, thereby preventing the formation of slugs etc. in the solidifying agent layer.

Furthermore, this solidifying agent not only has excellent water resistance, acid resistance, and weather resistance, but also has remarkable resistance to seawater. Furthermore, this solidifying agent has the unexpected property of fixing highly radioactive cesium and preventing its elution even when the waste contains highly radioactive cesium.

The invention is illustrated by the following example.

Example 1゜ The cement composition will be explained.

A-1 Water-soluble alkali borosilicate (binder agent, component (A)) The water-soluble alkali borosilicate is prepared according to the method described in the patent of the present inventors ('% Publication No. 57-42581). Sample number BF; S-1 of water-soluble sodium borosilicate powder having the following composition was mainly selected.

Table 1 A-2 Silicon polyphosphate (acid curing agent (1), component (B)
)) BoIJ Silicon 9-phosphate was prepared according to the method described in the specifications of two patents of the present inventors (Japanese Patent Publication No. 46-40866, Japanese Patent Publication No. 46-42711, and Japanese Patent Publication No. 57-42581). Sample No. Ps-1 of silicon polyphosphate having the following composition and characteristics was mainly selected.

Table 2 Note that the dispersibility and gelation time of the silicon polyphosphate prepared herein were measured by the measuring method described below, and the results are also shown in Table 4.

A) Measurement of dispersibility and gelation time Measurement of gelation time is carried out in accordance with the patent issued by the present inventors.
7-42581 and Japanese Patent Application No. 57-62277)
It was measured according to the method described in the specification.

In addition, regarding dispersibility, when water is added to a powder sample and the entire sample becomes a homogeneous paste when stirring is started, the dispersibility is considered to be good. It was determined that he had a sexual defect. Of course, samples with poor dispersibility cannot be used as the curing agent of the present invention.

A-3 Alkali fluorosilicide (acid curing agent (2), component (
As an alkali silicofluoride, the commercially available industrial chemical 7)
Sodium oxide (Nα2SiFa) powder was selected.

A-47 Anionic surfactant (water retention agent, component) The anionic surfactant is commercially available β-naphthalene sulfonic acid phorin powder with the trade name Demol N (
We mainly selected products manufactured by Kao Soap Co., Ltd.

A-5 Crystalline barium metasilicate (flow improver, component (C)) Crystalline barium metasilicate may be a commercially available product, but in this example, the following Reference Example 1 was used as a typical preparation method. Crystalline barium metasilicate sample number B5-1, prepared by the method described, was selected.

Reference example 1゜Flattary silica sand as a silicic acid source and patent (patent application 1983-42
581 Publication) An equimolar mixture of easily reactive silicic acid, which is a special silicic acid gel prepared by the method of Reference Example 10 described in the specification, and 7 Lattari silica sand, barium carbonate, a commercially available reagent, was selected as the barium source, and 5 sOt/ Adjust the molar ratio of BaO to 0.2 to 1, preferably 0.5 to 1, more preferably 1, mix both, and granulate with 15 to 20% water for about 10 minutes. After pulverizing into granules with a diameter of 6J]μ or less, they are fired in a rotary kiln at 900 to 1200°C, preferably 1000 to 1100°C for 0.5 to 1 hour, and then dry pulverized to a particle size of 6J] μ or less and 95% or more. A fractionated crystalline barium metasilicate salt was prepared.

Table 3 B) Measurement sample of water-soluble BaO (component (C)) 5 tons was weighed, placed in a 2001rL Erlenmeyer flask, added with 100% of distilled water, tightly stoppered, stirred for 30 minutes, separated, and placed in the solution F. The BaO component of the sample was analyzed, and the weight percent obtained by dividing the sample by 5 tons was taken as the water-soluble portion of the BaO component.

A-6 Amorphous barium silicate (filling stabilizer, component (D
)) As the amorphous barium silicate, sample number of amorphous barium silicate prepared according to the method tC of Example 2 described in the patent specification of the present inventors (Japanese Patent Application No. 57-42581) is used. I mainly chose BAL&-1.

The particle size distribution of the barium silicate prepared here is 1
0μ or less (50%), 10 to 30μ (60%
), 60 to 60μ (20% by weight), and the 5% water dispersion pli of this was 11, and the water soluble content of l'lao was 2.6% by weight.

A-7 Auxiliary As the auxiliary, the following powders were mainly selected as the auxiliary under conditions that do not reduce the fluidity of Nohaste as the cement composition of the present invention.

Product name Main ingredient Raw material number Calcium silicate <CaO8ift) AG -CS Magnesium silicate <Ma()Sift) AG -M
S fly ash C3iOx) AG-h
'1 Zeolite () AG-Z Portland Cement () Table 4 shows the cement composition as the basic formulation of this example using compounding agents of AG-PC or higher.

Table 4 B-1 Paste and solidified cement composition Using the six basic formulations shown in Table 1, anionic surfactant Demol N and auxiliary agents (ceolite, fly ash, etc.) were added. The hydraulic cement composition powder of each composition shown in Table 2 was made into a homogeneous paste by mixing the required amount of water, and this paste was poured into a mold (60φ x 50mm) under the conditions of a temperature of 25°C and a relative humidity of 75%. The physical properties and effects of the obtained solidified product were measured using the measurement methods described in A to H below, and the results are shown in Table 6. In addition, the seven members of the present invention) f, f
Comparative Example (Sample No. 111-1)
showed that.

As a result of the above, as is clear from Tables 5 and 6, the solidified cement composition consisting of the basic composition of the present invention hardens with syneresis phenomenon, and one solidified solidified product exhibits volumetric shrinkage. However, from the results of sample numbers 1-1 to 1 to 5, by adding the anionic surfactant Demol N, syneresis is suppressed, and as a result, the water retention of the assimilate is improved and the shrinkage rate is reduced. is understood.

Also, as a very interesting result, by incorporating Demol N as a water retention agent, the cement composition of the present invention can prevent the above-mentioned shrinkage and also improve water permeation resistance, which was a drawback of conventional hydraulic cement. It was found that this was significantly improved. Furthermore, by using zeolite as an auxiliary agent, further improvements can be seen in terms of water retention and water permeation resistance.

Demol Nu has conventionally been used as a water reducing agent for cement to improve the fluidity of cement paste, but in the cement composition yarn of the present invention, it tends to lower it and also tend to reduce the compressive strength. For this reason, the above-mentioned effect due to the addition of Demol is a feature found in the cement composition of the present invention, which was not found in conventional cement systems.

Furthermore, it is well understood that the combined use of zeolite and fly ash as auxiliary agents improves the compressive strength that tends to decrease, and also stabilizes the water permeation resistance.

A) Amount of water mixed: Weight % of added water in the paste B) 70-value sample powder is mixed with a predetermined amount of water (Xft%) to make a homogeneous aqueous paste, and at each time, a fixed amount of 5 ml is poured with a syringe at an inclination angle. Flow onto a glass inclined plate at an angle of 50°, measure the initial fall length (E) for 1 minute, and calculate that value as the flow value (cm/m1).
n), and the flow characteristics of the aqueous paste were evaluated from this value.

C) Solidification time The aqueous paste gels and hardens over time under conditions of a temperature of 25°C and relative humidity of 75%, and the time required for the surface of the solidified product to become clear of the hardness H lead wick is measured, and the assimilation time ( hr
).

D) Syneresis rate 1M Under the conditions of 25°C and relative humidity of 75%, inject a specified weight of pace) (H's) of a specified mixed product into a completely sealed container, and 4 days after photoacoustic assimilation, syneresis. Quickly wipe off the syneresis water on the surface of the molded solidified body, and the weight of the solidified body i: (Wt)
was measured, and then the syneresis rate was calculated using the following formula.

(14'+ Wt) 100 Syneresis rate -1□ O However, W. - Theoretical moisture content of the cement composition including the amount of mixed water
A paste with a predetermined water density was injected into the inner diameter DI), and the diameter (D) of the demolded assimilated product was measured 4 days after the assimilation of the dead metal, and then the shrinkage rate was calculated from the following formula.

F) Water permeability After immersing a solidified body with a diameter of 3.5 crrL and a thickness of 5 CIrL in red colored water under standing conditions, the assimilated body was sliced into three slices into colored water at the top, middle, and bottom. The penetrance (Il
llR) was measured from the side of the assimilate, and the water permeability was evaluated from the average value.

G) Water Resistance The assimilated product was immersed in electrostatic water, and was evaluated as water resistant if there was no change in shape such as cracking, collapse, or swelling for at least 60 days.

,,li) Bending and Compressive Strength The bending strength was measured by the 6-point bending method on a square cross-section specimen obtained in accordance with JIS-A1106K, which was subjected to 3-day cycles under the conditions of a temperature of 25°C and a relative humidity of 75%. Shifko. Also J
The compressive strength of a cylindrical specimen having a shape ratio of 2<L/D was measured in accordance with IS-A1114.

Example 2 Various resistances such as acid resistance, seawater resistance and leaching resistance of the cement composition of the present invention will be explained.

The various resistances of the assimilated cement compositions of the present invention having the formulations shown in Table 4 were evaluated by the methods described in I to K below, and the results are also shown in Table 4. In order to clarify the evaluation, ordinary cement (sample numbers 2H-1 and 2H-2) and acid-resistant cement (sample number 211-3) were used as comparative examples.

I) Acid resistance The compressive strength CP (h) was measured after the specimen was immersed in reduced acid at a concentration of 60% for 28 days, and the acid resistance was evaluated from the compressive strength (P ao) before immersion using the following formula.

Acid resistance = Cl-CPa. -PaI)/Pao]100
J) Seawater resistance After immersing the specimen in seawater for 28 days, the compressive strength (PtB) was measured, and the seawater resistance was evaluated from the compressive strength (P8o) before immersion using the following formula.

Seawater resistance = (1-(J'go-Pat)/Pso)
I DOK) Leaching resistance of seshum ions A specimen solidified with water containing a predetermined amount of seshum ions was immersed in a certain amount of pure water for 30 days. ) was calculated to evaluate the leaching resistance.

L) Resistance to leaching of seshum 1 After a specimen solidified with water containing a predetermined amount of seshum ions was immersed in pure water with a constant flow of VC for 40 days, the leaching resistance of seshum ions was determined. Delivery rate (foreign wealth%)
) was calculated, and the leaching resistance was planned based on this value (7).

As a result of the above, as is clear from Table 8, the solidified body made of the cement composition according to the present invention has better acid resistance, seawater resistance, and cesium ion leaching resistance than conventional hydraulic cement assimilates. It has been found that it is an assimilated substance with extremely excellent resistance to various conditions such as.

It is also well understood that fly ash as an auxiliary agent has effective synergy with the basic formulation of the present invention and Demol NvC in terms of acid resistance and seawater resistance, and zeolite has effective synergism with respect to leaching resistance. be done.

Example S An application example of the inventive hydraulic cement composition will be described.

6-1: Assimilation of pelleted radioactive waste Radioactive waste generated from nuclear power @electrodeposition is conventionally mixed homogeneously with cement or asphalt in a container such as a drum and solidified.
However, in the conventional method, the amount of radioactive waste that can be filled into a container is small, and the number of storage bodies increases, so there is a need to improve this volume reduction ratio.

In order to reduce the storage capacity of this storage body, dry powder of radioactive waste was pre-press-molded into a 35x2
Patent C JP-A-52-85699, JP-A-52-85700) has been filed in which the product is compression-molded into a 5 x 13 mm coconut-shaped solid pellet and then solidified with asphalt in a container.

Therefore, a pellet-shaped solid material (manufactured by Hitachi Factory, Hitachi, Ltd.) in accordance with the above patent was filled with 260 kf.
01 Aqueous paste 1 of the cement composition powder of the present invention of sample number 2-6 shown in Table 8 of Example 1 in a drum container
1 Qkg (approximately 65)) was injected in 8 minutes, and then left at a temperature of 25°C, and the product became completely solidified after 2 days.

Therefore, the actual volume of the 2001 drum is 1857, and when 260 kli of pellets are put into it, the void volume of the drum due to the pellet gap is approximately 65 J. The volume of the 110 kg of paste injected in this example is approximately 657' when calculated from the specific gravity of the paste (approximately 1.7).

From the above results, it was found that even when the cement composition of the present invention containing a fluidity improver is used at an extremely low mixing level, the paste penetrates into the fine voids created by the pellets created by the fine light in the container. It was found that the more completely the paste is filled, the more fluid the aqueous paste becomes.

Patent applicant: Mizusawa Chemical Industry Co., Ltd.

Claims (1)

[Claims] (11(A) a water-soluble alkali borosilicate or a combination of a water-soluble alkali silicate and an alkali borate soluble in an aqueous alkali solution, (B) an acidic curing agent for the alkali borosilicate, and CC) A hydraulic cement composition characterized by containing a water retention agent mainly consisting of an anionic surfactant. (2) Based on the solid content, 50 to 100 parts by weight of component (B) and component (C) per 100 parts by weight of component CA).
) in an amount of 0.1 to 20 parts by weight.