JP7172148B2 - SOIL IMPROVEMENT COMPOSITION AND USE THEREOF - Google Patents

Description

This specification relates to a soil improvement composition and its use.

Soil improvement agents have long been known as agents for improving soft ground, etc., and are used for temporary reinforcement during excavation work, ground improvement for building structures, and leakage prevention for underground structures such as subways, roads, and railway tunnels. It is used in a wide range of applications such as ground improvement for the purpose of (stopping water), liquefaction prevention and seismic isolation.

Various agents such as water glass-based, acrylic-based, polyvinyl alcohol-based, and urethane-based soil improvement agents are known. Among them, the acrylic soil improvement agent consists of a composition containing an acrylic monomer and a polymerization initiator, etc., has good permeability to the ground, and has an excellent main chain skeleton composed of carbon-carbon bonds. It is useful in that it can exhibit durability.

For example, Patent Document 1 discloses a composition for injection material containing a monovalent or divalent metal salt of (meth)acrylic acid, a trivalent metal salt, an oxidizing agent, two or more reducing agents having different reducing powers, and water. things are disclosed. Patent Document 2 discloses a (meth)acrylic acid-based chemical containing an aqueous solution of a monovalent or divalent metal salt of (meth)acrylic acid, an aqueous solution of a water-soluble aluminum salt, and an aqueous solution of bisulfite. Patent Document 3 discloses a ground grouting agent composition containing a metal (meth)acrylate, a polyvalent metal salt compound other than the metal (meth)acrylate, an oxidizing agent, a specific reducing agent, and water. ing.

Japanese Patent Application Laid-Open No. 2001-241288 JP 2006-104795 A JP 2016-130286 A

According to the present inventors, in the soil improvement agents described in Patent Documents 1 to 3, the radical polymerization reaction of (meth)acrylic acid is inhibited depending on the usage environment such as the ground to which it is applied, resulting in poor curing. all right. In particular, when the soil improvement agent is mixed with the soil or permeated into the soil and hardened, it has been found that poor hardening may become noticeable, and it is difficult to improve the ground to the desired strength. , and unreacted monomers remain.

The present specification provides a soil improvement agent composition that can reduce inhibition of polymerization reaction due to usage environment and ensure good reactivity.

The present inventors have made intensive studies in view of the above problems, and found that the addition of an inorganic salt in a soil improvement agent composition that uses curing of a vinyl-based unsaturated monomer stabilizes it regardless of the type of ground. It has been found that the monomer can be polymerized and cured by This specification provides the following means based on this knowledge.

[1] A soil improvement agent composition,
The following (A) to (D) components:
A composition comprising (A) a vinyl-based unsaturated monomer or a salt thereof (B) a polymerization initiator (C) an inorganic salt (D) water.
[2] The composition according to [1], wherein the total amount of component (C) is 0.05% by mass or more.
[3] The composition according to [1] or [2], which has a pH of 4.0 or more and 9.0 or less.
[4] The composition according to any one of [1] to [3], which has a cation exchange capacity of 0.3 meq/100 g or more and is for soil improvement.
[5] Furthermore, component (E):
(E) one or more crosslinking agents selected from the group consisting of a crosslinkable polyvalent metal salt compound and a monomer having two or more vinyl unsaturated groups of [1] to [4] A composition according to any one of the preceding claims.
[6] The composition according to [5], wherein the total amount of the component (A) and the component (E) is 1.0% by mass or more and 40% by mass or less.
[7] A kit for ground improvement,
a vinyl-based unsaturated monomer or a salt thereof;
a polymerization initiator;
an inorganic salt;
kit.
[8] A ground improvement method,
A method comprising the step of curing the soil improvement agent composition according to any one of [1] to [6] in the ground.

This specification provides a soil improvement composition and its use. The soil improvement agent composition disclosed in the present specification (hereinafter also simply referred to as "the composition") is a vinyl-based unsaturated monomer or a salt thereof that is a curable component for soil improvement, and a polymerization In addition to containing an initiator and water, it also contains an inorganic salt. According to the present composition, by containing an inorganic salt, polymerization and hardening of the vinyl-based unsaturated monomer can be achieved regardless of the use environment, generally the clay property of the soil or ground, the cation exchange capacity, and the like. It is possible to stably promote and suppress or avoid poor hardening of the gelled product (gel product) obtained in the ground. Therefore, it is possible to stably obtain a gel having sufficient strength. Therefore, the present composition can be applied to a wide range of applications such as temporary ground reinforcement during excavation work and permanent ground improvement for building structures and the like.

The soil improvement method disclosed in the present specification (hereinafter also referred to as "this method") and kit (hereinafter also referred to as "this kit"), etc. can also produce the same effect as the present composition. can.

As used herein, "(meth)acryl" means acrylic and / or methacrylic, "(meth)acrylate" means acrylate and / or methacrylate, and "(meth)acrylamide" means acrylamide and/or methacrylamide.

As used herein, the term "soil improvement agent" includes agents used for soil improvement for various purposes. Here, "soil improvement" includes, for example, water leakage prevention, water stoppage, liquefaction prevention, and ground strengthening. Ground consolidation method, water stoppage method, injection solidification method (or chemical injection method), jet grouting method, and the like.

Embodiments of the composition, the method, and the like are described in detail below.

<Soil improvement agent composition>
The present composition contains (A) component: vinyl-based unsaturated monomer or salt thereof, (B) component: polymerization initiator, (C) component: inorganic salt, and (D) component: water. be able to. The present composition further contains (E) component: one or more cross-linking agents selected from the group consisting of a cross-linkable polyvalent metal salt compound and a monomer having two or more vinyl unsaturated groups. can do.

<(A) component: vinyl-based unsaturated monomer or salt thereof>
The vinyl-based unsaturated monomer in the vinyl-based unsaturated monomer or its salt contained in the present composition includes an ionic monomer (anionic monomer or cationic monomer) and a nonionic monomer. Any of these may be used, and a combination thereof may also be used. In addition, a vinyl-type unsaturated monomer means the monofunctional monomer provided with only one polymerizable unsaturated group.

Examples of anionic monomers or salts thereof include (meth)acrylic acid, itaconic acid, itaconic acid monoalkyl ester, maleic acid, maleic acid monoalkyl ester, fumaric acid, fumaric acid monoalkyl ester, citraconic acid, citracone Carboxyl group-containing monomers such as acid monoalkyl esters, cinnamic acid, itaconic anhydride and maleic anhydride, or salts or anhydrides thereof; 2-acrylamido-2-methylpropanesulfonic acid, vinylsulfonic acid, allylsulfonic acid, lylsulfonic acid, styrenesulfonic acid, polyoxyalkylene mono(meth)acrylate sulfuric acid, 2-hydroxyethyl(meth)acryloyl phosphate, phenyl-2-acryloyloxyethyl phosphate, 2-acryloyloxyalkylphosphonic acid and the like. Although not particularly limited, for example, (meth)acrylic acid or a salt thereof, 2-acrylamido-2-methylpropanesulfonic acid or a salt thereof can be preferably used from the viewpoint of polymerizability and solubility in water. .

Examples of salts of anionic monomers include alkali metal salts such as lithium salts, sodium salts and potassium salts; alkaline earth metal salts such as calcium salts and barium salts; magnesium salts, aluminum salts, zirconium salts; ammonium salts and the like. These monomers and salts thereof may be used alone or in combination of two or more. Among these metal salts, calcium salts, magnesium salts and the like are preferable from the viewpoint of obtaining a gel having good strength and deformation resistance.

Examples of cationic monomers or salts thereof include tertiary monomers such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylamide, diethylaminopropyl (meth)acrylamide and salts thereof. Amino group-containing compounds; (meth)acryloyloxyethyltrimethylammonium chloride, (meth)acryloyloxyethyldimethylbenzylammonium chloride, (meth)acryloylaminopropyltrimethylammonium chloride, (meth)acryloylaminopropyldimethylbenzylammonium chloride, (meth)acryloylaminopropyldimethylbenzylammonium chloride, (meth) Quaternary ammonium base-containing compounds such as acryloyloxy 2-hydroxypropyltrimethylammonium chloride and the like can be used. These monomers and salts thereof may be used alone or in combination of two or more.

Examples of nonionic monomers or salts thereof include (meth)acrylamide, dimethylacrylamide, diethylacrylamide, isopropylacrylamide, hydroxyethylacrylamide, vinylpyrrolidone, vinylformamide, vinylacetamide, (meth)acrylic acid-2-hydroxy Ethyl, polyoxyalkylene mono(meth)acrylate, polyoxyalkylene alkyl allyl ether, glycerin monoallyl ether, salts thereof and the like. These monomers and salts thereof may be used alone or in combination of two or more. The nonionic monomer is not particularly limited, but from the viewpoint of polymerizability and solubility in water, for example, (meth)acrylamide, dimethyl(meth)acrylamide, diethyl(meth)acrylamide, isopropyl (meth) ) Acrylamide, (meth)acrylamide such as hydroxyethyl (meth)acrylamide, and derivatives thereof can be preferably used. Among them, (meth)acrylamide is more preferable.

The concentration of the vinyl-based unsaturated monomer or salt thereof in the present composition is not particularly limited, but is, for example, 0.5% by mass or more, or, for example, 1.0% by mass or more, or, for example, 2% by mass or more. .0% by weight or more, for example 4.0% by weight or more, or for example 6.0% by weight or more. If the concentration of the vinyl-based unsaturated monomer or its salt is 0.5% by mass or more, the obtained gel will have sufficient strength. Further, the concentration of the vinyl-based unsaturated monomer or its salt in the present composition is not particularly limited, but is, for example, 40% by mass or less, or, for example, 30% by mass or less, or, for example, 20% by mass. % or less, and for example, 15% by mass or less. If the concentration is 40% by mass or less, it is easy to ensure the stability of the soil improvement agent composition.

Although not particularly limited, when a crosslinking agent described later is used in combination with the present composition, the concentration of the vinyl-based unsaturated monomer or salt thereof is, for example, 39.5% by mass or less, and for example, It is 39.0% by mass or less, or, for example, 38.5% by mass or less. The concentration is also, for example, 30% by mass or less, or, for example, 20% by mass or less, or, for example, 15% by mass or less, or, for example, 10% by mass or less.

The range of the concentration of the vinyl-based unsaturated monomer or salt thereof can be set by combining these lower limit concentration and upper limit concentration. 0% by mass or more and 30% by mass or less, or, for example, 2.0% by mass or more and 15% by mass or less. The concentration of the vinyl-based unsaturated monomer or salt thereof in the present composition is also defined by the total amount together with the concentration of the cross-linking agent and the like, which will be described later.

<(B) component: polymerization initiator>
The polymerization initiator is added to polymerize the vinyl-based unsaturated monomer or its salt in the present composition, and various known polymerization initiators applied to the vinyl-based unsaturated monomer or its salt. can be used. For example, from the viewpoint of pot life, control of curing time from ground injection to curing (gelation), etc., azo initiators, inorganic peroxides such as peroxodisulfate, organic peroxides such as percarboxylic acids, hydroperoxides, etc. Peroxides and the like can be used. When using an oxidizing agent that is an inorganic peroxide or an organic peroxide, a reducing agent can be used in combination as appropriate.

Azo initiators, for example, generally decompose more slowly than redox initiators, and can ensure a pot life of, for example, several days. Examples of azo initiators include 2,2′-azobis[2-(imidazolin-2-yl)propane], 2,2′-azobis[2-(imidazolin-2-yl)propane] dihydrochloride, 2, 2'-azobis (2-methylpropionamidine) dihydrochloride, 2,2'-azobis [2-(5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- methyl-N-(2-hydroxyethyl)propionamide], 4,4′-azobis(4-cyanovaleric acid) and the like, which may be used alone or in combination of two or more. good. Among these, 2,2′-azobis[2-(imidazolin-2-yl)propane], 2,2′-azobis[2-(imidazolin-2-yl) Propane] dihydrochloride is preferred.

The inorganic peroxide is not particularly limited, and known inorganic peroxides can be used. For example, peroxides such as sodium percarbonate, sodium perborate, sodium peroxide, calcium peroxide, barium peroxide and hydrogen peroxide, and inorganic persulfate compounds such as sodium persulfate, potassium persulfate and ammonium persulfate. and these may be used alone or in combination of two or more.

Although the organic peroxide is not particularly limited, considering the composition and usage environment of the present composition, it is preferably highly hydrophilic. From this point of view, for example, an organic peroxide having 15 or less carbon atoms as a whole can be used, for example, an organic peroxide having 10 or less carbon atoms, and for example, an organic peroxide having 8 or less carbon atoms can be used. The number of carbon atoms in the organic peroxide can be, for example, 2 or more, or can be, for example, 3 or more. A preferable range of the total carbon number of the organic peroxide can be set by appropriately combining the above-mentioned upper limit and lower limit, and is, for example, 2 or more and 10 or less, or, for example, 3 or more and 8 or less.

Further, the organic peroxide is preferably hydrophilic, but ketone peroxides, hydroperoxides, percarboxylic acids, diacyl peroxides, etc. generally tend to have high water solubility. Among them, hydroperoxides tend to be more water soluble.

Examples of organic peroxides include diacyl peroxide, peroxydicarbonate, peroxyester, tetramethylbutylperoxyneodecanoate, bis(4-butylcyclohexyl)peroxydicarbonate, di(2-ethylhexyl)peroxycarbonate, butylperoxy Neodecanoate, dipropylperoxydicarbonate, diisopropylperoxydicarbonate, diethoxyethylperoxydicarbonate, diethoxyhexylperoxydicarbonate, hexylperoxydicarbonate, dimethoxybutylperoxydicarbonate, bis(3-methoxy-3-methoxy butyl peroxydicarbonate, dibutyl peroxydicarbonate, dicetyl peroxydicarbonate, dimyristyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxypivalate, hexyl peroxypivalate, butyl peroxypivalate, trimethylhexa noyl peroxide, dimethyl hydroxybutyl peroxyneodecanoate, amyl peroxyneodecanoate, butyl peroxyneodecanoate, t-butyl peroxyneoheptanoate, amyl peroxypivalate, t-butyl peroxypivalate, t-amyl Peroxy-2-ethylhexanoate, lauryl peroxide, dilauroyl peroxide, didecayl peroxide, t-butyl hydroperoxide, p-cumyl hydroperoxide, t-amyl hydroperoxide, 1,1,3,3-tetra Hydroperoxides such as methyl butyl hydroperoxide, percarboxylic acids such as peracetic acid and perbenzoic acid, methyl ethyl ketone peroxide or benzoyl peroxide (benzoyl peroxide) and the like, which may be used singly or in combination of two or more. may be used in combination. From the viewpoint of water solubility, hydroperoxides such as t-butyl hydroperoxide, p-cumyl hydroperoxide, t-amyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, and methyl ethyl ketone peroxide. Ketone peroxides, percarboxylic acids such as peracetic acid and perbenzoic acid, diacyl peroxides such as benzoyl peroxide are preferred. Organic oxidants such as organic peroxides are preferable in that they tend to increase the reaction rate in the ground more easily than inorganic oxidants.

(reducing agent)
The reducing agent that can be used in combination with inorganic peroxides and organic peroxides is not particularly limited, and known inorganic reducing agents and organic reducing agents can be used. Specific compounds of the inorganic reducing agent include thiosulfate compounds such as sodium thiosulfate and potassium thiosulfate, bisulfite compounds such as sodium bisulfite and potassium bisulfite, sodium hypophosphite and potassium hypophosphite. and hypophosphite compounds, sulfite compounds such as sodium sulfite and potassium sulfite, ferrous salts, and copper salts such as copper sulfate. Specific compounds of the organic reducing agent include hydroxymethanesulfinates such as sodium hydroxymethanesulfinate (Rongalit), ascorbic acid or salts thereof such as sodium ascorbate, erythorbic acid or salts thereof such as sodium erythorbate, dioxide In addition to thiourea and thiourea disulfide, amines such as diethanolamine, triethanolamine, hydrazine, hydroxylamine, dimethylaminopropionitrile, dimethylaminopropanol, piperazine and morpholine, and the like can be mentioned. These may be used alone or in combination of two or more.

The concentration and amount of the polymerization initiator used depends on the type and concentration of the vinyl-based unsaturated monomer or its salt, the type and concentration of the cross-linking agent described later, the type of ground/soil, conditions such as pH and water temperature, curing time, etc. may be appropriately selected depending on the application of the present composition, taking into account the set value of . Moreover, in the case of a redox initiator, a combination of an oxidizing agent and a reducing agent can also be appropriately selected.

The concentration of the polymerization initiator in the present composition (excluding the amount of reducing agent when used in combination with a reducing agent) can be, for example, about 0.1 mM or more and 200 mM or less, and can be, for example, about 1 mM or more and 100 mM or less. For example, it can be about 1 mM or more and 50 mM or less, and for example, it can be about 1 mM or more and 20 mM or less. When a reducing agent is used in combination, the concentration of the inorganic peroxide and the organic peroxide in the present composition is, for example, 0.1 mM or more and 100 mM or less, or, for example, 1 mM or more and 100 mM or less, or, for example, 1 mM or more. 20 mM or less. In addition, the concentration of the reducing agent in the present composition can be, for example, about 1 mM to 100 mM, and can be, for example, about 1 mM to 40 mM.

<(C) component: inorganic salt>
The composition may contain inorganic salts. Since the composition contains an inorganic salt, even when applied to soil having a high cation exchange capacity, the polymerization reaction proceeds without being inhibited, and the hardening component remains unreacted. It is possible to suppress or avoid remaining as it is. The reason why the above effect is obtained by containing the inorganic salt is not clear, but when the present composition is applied to the soil, the cationic component contained in the inorganic salt adsorbs to the negative charges in the soil. , (A) is considered to suppress or reduce the polymerization inhibition of the component (A). In addition, said reason is a guess and does not limit the scope of the present invention.

The inorganic salt may be a metal salt or a non-metal salt. As the metal salt, it is preferable to use a monovalent or divalent metal because of its high solubility in water and excellent long-term storage stability. Regarding inorganic salts, examples of monovalent or divalent metals include, but are not limited to, alkali metals such as lithium, sodium and potassium; alkaline earth metals such as calcium. Specific examples include sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sodium sulfate, potassium sulfate, calcium sulfate, magnesium sulfate, sodium nitrate, calcium nitrate and the like. Examples of non-metal salts include, but are not particularly limited to, ammonium chloride, ammonium sulfate, and the like. These compounds may be used alone or in combination of two or more. The inorganic salt as the component (C) does not include compounds such as inorganic peroxides and inorganic reducing agents that correspond to the component (B).

Moreover, the inorganic salt contained in the present composition is not limited to the normal salt as described above, and may be, for example, an acid salt or a basic salt.

The concentration and amount of inorganic salt used are determined appropriately by considering conditions such as the type and concentration of the vinyl-based unsaturated monomer or its salt, the type and concentration of the cross-linking agent described later, the type of ground/soil, pH, and water temperature. You can choose. The concentration of the inorganic salt in the present composition is not particularly limited, but is, for example, 0.05% by mass or more, or, for example, 0.1% by mass or more, or, for example, 0.5% by mass or more. Also, for example, it is 1.0% by mass or more, or is, for example, 1.5% by mass or more, or is, for example, 2.0% by mass or more, or is, for example, 5.0% by mass or more. When the concentration of the inorganic salt in the present composition is 0.05% by mass or more, inhibition of the polymerization reaction of the present composition can be preferably reduced. In addition, although the concentration of the inorganic salt in the present composition is not particularly limited, it is, for example, 20% by mass or less, or, for example, 15% by mass or less, or, for example, 10% by mass or less. Furthermore, the concentration range of the inorganic salt can be set by appropriately combining these lower and upper limits, and is, for example, 0.1% by mass or more and 10% by mass or less, or, for example, 0.5% by mass or more and 5% by mass or less. is.

In addition, the lower limit of the ratio of the inorganic salt to the total amount of component (A) in the present composition is not particularly limited, but is, for example, 1% by mass or more, or, for example, 5% by mass or more, or, for example, 10% by mass or more. % by mass or more, for example 40% by mass or more, for example 80% by mass or more, or for example 100% by mass or more. The upper limit of the ratio is not particularly limited, but is, for example, 300% by mass or less, or, for example, 250% by mass or less, or, for example, 200% by mass or less, or, for example, 150% by mass or less. . Furthermore, the range of the ratio can be set by appropriately combining these lower and upper limits, and is, for example, 1% by mass or more and 250% by mass or less, or, for example, 10% by mass or more and 150% by mass or less.

<(D) component: water>
The composition can contain water. The composition is applied to the ground in the form of an aqueous solution or suspension. Water in the present composition can dissolve or disperse various components and can function as a medium for transporting these components to the ground, and the like. Water can also function as a modifier, such as curing time. In addition to water, the present composition may contain an organic solvent that dissolves and disperses the various components described above within a range that does not impair the effects of the present composition.

Water in the present composition generally corresponds to components (A) to (C) in the present composition, and the remainder excluding (E) and other components, which are included as necessary and which will be described later. The concentration of water in the present composition is not particularly limited, but is, for example, 50% by mass or more, or is, for example, 60% by mass or more, or is, for example, 70% by mass or more, or is, for example, 80% by mass. and so on.

<(E) component: cross-linking agent>
The present composition can contain one or more cross-linking agents selected from the group consisting of cross-linkable polyvalent metal salt compounds and monomers having two or more vinyl unsaturated groups.

(Crosslinkable polyvalent metal salt compound)
The crosslinkable polyvalent metal salt compound is a trivalent or higher polyvalent metal salt compound (hereinafter also simply referred to as the polyvalent metal salt compound). The present polyvalent metal salt compound crosslinks the polymer of component (A), polymerizes in water to form a stable gel, and can improve its strength, dimensional stability and durability.

With respect to the polyvalent metal salt compound, examples of trivalent or higher metals include, but are not limited to, aluminum, zirconium, titanium and cerium. Specific compounds include, for example, aluminum chloride, aluminum nitrate, aluminum sulfate, alum, sodium alum, aluminum acetate, aluminum lactate, polyaluminum chloride (basic aluminum chloride) and polysulfate chloride (basic aluminum sulfate chloride). zirconium salts such as aluminum salts such as zirconium acetate, zirconium nitrate, zirconium chloride, zirconium lactate, zirconium carbonate, zirconium oxynitrate, zirconium oxyacetate, zirconium sulfate and zirconium oxysulfate; titanium chloride and cerium nitrate; Among them, aluminum salts and zirconium salts are more preferable, and aluminum salts are more preferable. These compounds may be used alone or in combination of two or more.

The concentration of the present polyvalent metal salt compound in the present composition is not particularly limited. The concentration of the present polyvalent metal salt compound is converted into the oxide of the metal contained in the present polyvalent metal salt compound, that is, the metal oxide corresponding to the present polyvalent metal salt compound (hereinafter referred to as the present polyvalent metal salt compound For the concentration of, the conversion is used.), for example, 0.1% by mass or more, or, for example, 0.5% by mass or more, or, for example, 1.0% by mass or more, or, for example, 1.5% by mass % or more. If the concentration is 0.1% by mass or more, the obtained gel will have sufficient strength. In addition, the concentration is not particularly limited, but is, for example, 10% by mass or less, or, for example, 8.0% by mass or less, or, for example, 6.0% by mass or less, or, for example, 4.0% by mass. % or less. If the concentration is 10% by mass or less, good permeability to the ground can be ensured. The range of the same concentration can be set by combining these lower limit concentration and upper limit concentration, but is, for example, 0.5% by mass or more and 10% by mass or less, or, for example, 1.0% by mass or more and 8.0% by mass. or less, and for example, 1.0% by mass or more and 4.0% by mass or less. In addition, this polyvalent metal salt compound has lower solubility than the above-described component (C). Therefore, when the concentration is higher than 10% by mass, the present polyvalent metal salt compound may precipitate without being suitably dissolved. Moreover, since the present polyvalent metal salt compound acts as a cross-linking agent for the component (A), it is preferable that the concentration thereof is equal to or less than the total amount of the component (A).

The content of the present polyvalent metal salt compound depends on the type of component (A) and the type of component (E) used. On the other hand, it can be 60% by mass or less, for example, 50% by mass or less, or for example, 40% by mass or less, or for example, 30% by mass or less, and For example, it can be 20% by mass or less.

(Monomer having two or more vinyl unsaturated groups)
A monomer having two or more vinyl unsaturated groups (hereinafter also simply referred to as "this polyvalent vinyl unsaturated monomer") crosslinks the polymer of component (A) to form a polymer in water. to form a stable gel and improve its strength, dimensional stability and durability.

As the polyvalent vinyl-based unsaturated monomer, a known vinyl-based unsaturated monomer having a valence of 2 or more can be used. Examples include water-soluble divinyl monomers such as acrylamide, and polyfunctional allyl ether compounds such as pentaerythritol triallyl ether.

The concentration of the present polyvalent vinyl-based unsaturated monomer in the present composition is not particularly limited, but is, for example, 0.5% by mass or more, or, for example, 1.0% by mass or more, or, for example, It is 1.5% by mass or more, or, for example, 2.0% by mass or more. If the concentration of the present polyvalent vinyl-based unsaturated monomer is 0.5% by mass or more, the obtained gel product will have sufficient strength. Further, the concentration of the polyvalent vinyl-based unsaturated monomer is not particularly limited, but is, for example, 10% by mass or less, or, for example, 8% by mass or less, or, for example, 6% by mass or less, Moreover, it is 4 mass % or less, for example. If the concentration of the present polyvalent metal salt compound is 10% by mass or less, it is possible to ensure good permeability to the ground. The range of the concentration of the present polyvalent vinyl unsaturated monomer can be set by combining these lower limit concentration and upper limit concentration. 0% by mass or more and 8.0% by mass or less, or for example, 1.0% by mass or more and 4.0% by mass or less.

In addition, the concentration of the present polyvalent vinyl-based unsaturated monomer is not polyvalent, that is, a non-crosslinkable vinyl-based unsaturated monomer having only one vinyl-based unsaturated group (hereinafter referred to as "non-crosslinked Also referred to as "sexy monomer". % by mass or more. If the concentration of the present polyvalent vinyl unsaturated monomer relative to the non-crosslinkable monomer is 0.1% by mass or more, the strength of the obtained gel will be sufficient. Further, the concentration of the present polyvalent vinyl-based unsaturated monomer relative to the non-crosslinkable monomer is not particularly limited, but is, for example, 2000% by mass or less, or, for example, 1000% by mass or less, and for example, It is 500% by mass or less, or, for example, 100% by mass or less, or, for example, 50% by mass or less.

<Total Concentration of Components (A) and (E)>
Consists of a vinyl-based unsaturated monomer or a salt thereof as the component (A) in the present composition, and a crosslinkable polyvalent metal salt compound and a monomer having two or more vinyl-based unsaturated groups as the component (E). The total concentration of one or more cross-linking agents selected from the group is not particularly limited, but considering the strength of the resulting gel product and the rate of polymerization/curing reaction, for example, 1.0 % or more is preferable. From the viewpoint of more preferable gel strength and curing speed, the total concentration is, for example, 2.0% by mass or more, or, for example, 3.0% by mass or more, or, for example, 4.0% by mass or more. Also, for example, it is 5.0% by mass or more, and is, for example, 6.0% by mass or more. Although the total concentration is not particularly limited in consideration of the suppression of precipitate formation and the permeability to the ground, it is preferably 50% by mass or less, for example. From the viewpoint of better penetration into the ground, the total concentration is, for example, 45% by mass or less, or, for example, 40% by mass or less, or, for example, 35% by mass or less, or, for example, 30% by mass or less. or, for example, 25% by mass or less, or, for example, 20% by mass or less, or, for example, 18% by mass or less, or, for example, 16% by mass or less, or, for example, 14% by mass or less, or, for example, It is 12% by mass or less. The range of the total concentration can be set by combining the lower limit concentration and the upper limit concentration, and is, for example, 1.0% by mass or more and 40% by mass or less, or, for example, 2.0% by mass or more and 30% by mass or less. and is, for example, 3.0% by mass or more and 20% by mass or less, and is, for example, 4.0% by mass or more and 16% by mass or less.

<Other ingredients>
The present composition can contain various components within a range that does not impair the effects of the present composition. For example, other soil improvement agents such as known water glass can also be included. In addition, known rust inhibitors such as quaternary ammonium salts, organic acid amine salts, aromatic compounds, nitrites, alcohols, hexamethylenetetramine, and known antiseptics such as silicones, mineral oils, vegetable oils, and higher alcohols. One or more selected from foaming agents, known emulsifiers and known metal sealing agents may be contained as appropriate.

In addition, the present composition can also be blended with an aggregate as needed to increase or reinforce the gel product. As the aggregate, powders such as cement, fly ash, diatomaceous earth, calcium carbonate, kaolin, clay, bentonite, perlite, vermiculite, blast furnace slag, gypsum, silica sand, pulp and carbon powder, and various fibers can be used. . If the amount of aggregate used is too large, it may reduce the fluidity of the composition and the bending strength of the gel. preferable. When the aggregate precipitates in the composition, an anti-settling agent or the like can be used together.

<pH of the present composition>
Preferably, the composition has a pH close to the neutral range. A specific pH value is, for example, more than 3.5 and less than 10.0, and more than or equal to 4.0 and less than 9.5. Within this range, good reactivity of the present composition can be ensured. From the viewpoint of ensuring more suitable reactivity, the Moreover, it is 5.5 or more and 7.0 or less, for example.

<Use of this composition>
In the present composition, a polymerization reaction proceeds with a polymerization initiator to form a gel product. Therefore, the present composition can be directly injected into the ground and used for gelling in the ground. According to the present composition, the polymerization of the vinyl-based unsaturated monomer or its salt can be stably promoted regardless of the properties of the ground/soil, so that a firm gel can be formed in the ground. Therefore, the present composition can be widely applied to various forms of excavation work and ground improvement.

<Kit for ground improvement>
A kit disclosed herein can comprise a vinyl-based unsaturated monomer or a salt thereof, a polymerization initiator, and an inorganic salt. According to the present kit, one or more of these components can be provided as an aqueous composition such as an aqueous solution, respectively, and mixed at the time of use to prepare the present composition, or separately prepared components. The present composition can also be prepared by mixing and/or dissolving the vinyl-based unsaturated monomer or its salt, the polymerization initiator and the inorganic salt with water at the time of use. After preparing the present composition, various properties of the present composition can be exhibited. In addition, this kit can also be equipped with water.

In addition, when the present kit is provided with a vinyl-based unsaturated monomer or its salt, a polymerization initiator and an inorganic salt for preparation at the time of use, the polymer may be prepared separately from the vinyl-based unsaturated monomer or its salt and the inorganic salt. By providing the initiator, it becomes possible to easily secure a sufficient pot life and utilize the present composition. According to this kit, it is possible to solve problems related to manufacturing, distribution, storage, etc., and the short pot life in ground improvement work, etc.

The present kit can take the form of a kit in which the vinyl-based unsaturated monomer or salt thereof is separately provided in such a manner that the polymerization initiator does not act on it. Such a separate storage mode is not particularly limited, but for example, various components may be separated into two or more packages, or one package having two or more compartments or storage areas Various components may be separated.

In addition, the composition may be prepared from the kit and injected into the ground through the injection tube prior to the injection into the ground, or one or more components of the kit may be separately injected into the injection tube. The composition may be prepared by injecting and mixing in the injection tube.

The contents of the vinyl-based unsaturated monomer or its salt, the polymerization initiator and the inorganic salt in the kit are not particularly limited. A required amount of each component may be weighed at the time of preparation, or the composition may be weighed in advance so that the concentration and pH are suitable for the present composition. Moreover, it may be subdivided into fixed amounts so that the required amount can be easily weighed.

In the present kit, for example, each component is preferably weighed in advance so as to achieve the intended concentration of each component in the present composition to be prepared.

Also, the vinyl-based unsaturated monomer or its salt, the polymerization initiator and the inorganic salt may be appropriately dissolved in water or the like, or may be used as such (powder, liquid, etc.). It is appropriately selected depending on the handleability, stability and physical properties of each component.

The present composition and the present kit can be applied, for example, to soil having a cation exchange capacity of 0.3 meq/100 g or more, and can also be applied to soil having a cation exchange capacity of 0.4 meq/100 g or more, Further, for example, it can be applied to soil of 0.5 meq/100 g or more, for example, it can be applied to soil of 1.0 meq/100 g or more, and for example, to soil of 2.0 meq/100 g or more. can also be applied, for example, it can be applied to soil of 3.0 meq/100 g or more, for example, it can be applied to soil of 4.0 meq/100 g or more, and for example, 6. It can be applied to soil of 0 meq/100 g or more, and can also be applied to soil of 8.0 meq/100 g or more, for example. Although the upper limit of the cation exchange capacity of soil is not particularly limited, it is, for example, 20 meq/100 g or less, or 15 meq/100 g or less.

In addition, the cation exchange capacity of soil can be measured according to the Shollen-Berger method for a dried soil sample. Specifically, it can be carried out by measuring the ammonium ion concentration by the indophenol blue absorptiometry (JIS K 0102).

<Soil Improvement Method>
The soil improvement method disclosed herein can comprise the step of hardening the composition in the soil. According to this method, regardless of the properties of the soil to be applied, or in accordance with the properties of the soil to be applied, the polymerization reaction of the vinyl-based unsaturated monomers can be stably advanced to polymerize and harden. It is possible to obtain a gel product with excellent properties.

This method can be applied to various types of ground improvement described above. Specific construction methods include the various construction methods already described. In the present method, the step of introducing the present composition can be carried out by injecting the present composition into the ground in a known manner according to the intended use and construction method. In general, one or more liquids to be injected are pumped through an injection pipe placed in the ground by a pump or the like, separately or while being mixed in the injection pipe, etc., to the ground. Introduce.

This method is suitable for the injection solidification method (chemical solution injection method). In the injection solidification method (chemical injection method), the present composition is permeated and injected into the sandy ground, and after replacing the water present in the interstices of the sandy ground with an infusion agent, the infusion agent gels to bind the sandy ground. It is a ground improvement method that has functions such as leakage prevention, water stoppage, liquefaction prevention, and ground reinforcement. It is a construction method that injects a chemical solution into the necessary places from an injection pipe using a relatively small-scale device and solidifies it. For example, it is effective as a countermeasure against liquefaction of the ground directly under existing structures that are difficult to move, such as tanks and bridge piers. ground improvement method. This composition can ensure sufficient or appropriate gel time and can obtain excellent gel strength, so it exhibits excellent performance when applied to the injection solidification method (chemical injection method). be able to.

Hereinafter, the disclosure of the present specification will be specifically described with specific examples. However, the disclosure of this specification is not limited to the following specific examples. In the following description, "parts" means parts by mass and "%" means % by mass unless otherwise specified.

Below, the evaluation method of the soil improvement agent composition is described, and then each example and the like are described.

[1] pH of the composition
It was measured with a pH meter.
[2] Monomer Reaction Rate 50 g of each composition described later and 12 g of test soil were added to a 50 mL resin bottle to prepare a mixture in which the composition and the test soil were blended. After that, it was left at rest at 23° C. for 3 days, the mixture in the bottle was taken out, and unreacted monomer was extracted with water. After the extract was treated with an ion-exchange resin to restore the acrylate to an acid form, it was quantified by gas chromatography and converted into a monomer reaction rate.

<Example 1>
17.9 g of water, 2.5 g (5.0% by mass) of calcium chloride, 5.71 g (4.0% by mass) of a 35% concentration magnesium acrylate aqueous solution, and a 23% concentration polychloride as a cross-linking agent. 4.35 g (2.0% by weight) of aluminum were dissolved. A mixture of 0.065 g (10 mM) of t-butyl hydroperoxide (PBH) with a concentration of 69% as an oxidizing agent, 0.16 g (20 mM) of sodium thiosulfate and 19.3 g of water was added to this solution, and A soil improvement composition of Example 1 was prepared. Using purified bentonite (Kunimine Industry Co., Ltd., Kunipia F, cation exchange capacity 1 meq/100 g) as test soil, the monomer reaction rate was evaluated.

<Examples 2-12, Comparative Examples 1-2>
Examples 2-12 and Comparative Examples 1-2, except that each component was used as shown in Table 1, the same operation as in Example 1 was performed to prepare each soil improvement agent composition. In addition, ammonium chloride was used as an inorganic salt in Example 9, ammonium sulfate in Example 10, and potassium chloride in Examples 11 and 12, respectively. In Comparative Examples 1 and 2, no inorganic salt was added.

<Examples 13-14, Comparative Examples 3-4>
Examples 13-14, Comparative Examples 3-4, except that each component was used as shown in Table 2, the same operation as in Example 1 was performed to prepare a soil improvement agent composition. In Example 13 and Comparative Example 3, a mixture of 9 g of Toyoura silica sand (manufactured by Toyoura Silica Mining Co., Ltd.) and 3 g of Kunipia F was used as test soil (cation exchange capacity: 0.51 meq/100 g). In Example 14 and Comparative Example 4, a mixture of 6 g of Toyoura silica sand and 6 g of Kunipia F was used as test soil (cation exchange capacity: 0.74 meq/100 g).

The descriptions in Tables 1 and 2 are supplemented below.
AAMg: magnesium acrylate TAH: t-amyl hydroperoxide PBH: t-butyl hydroperoxide Thio: sodium thiosulfate PAC: polyaluminum chloride (83% basicity)
CEC: cation exchange capacity

As shown in Tables 1 and 2, Examples 1-14 were found to exhibit higher monomer conversions than the corresponding Comparative Examples containing no inorganic salt. In addition, it was found that the monomer conversion rate improved depending on the concentration of the inorganic salt (eg, Examples 1 to 5), and that the type of inorganic salt contributed to the monomer conversion rate (Examples 9 to 12). Furthermore, focusing on the cation exchange capacity of the soil, it was confirmed that the effect exhibited by the present composition becomes more pronounced when applied to soil having a high cation exchange capacity.

Claims (12)

A soil improvement agent composition,
The following (A) to (E) components:
(A) vinyl unsaturated monomer or salt thereof (B) polymerization initiator (C) monovalent or divalent inorganic salt (however, silicate, aluminate, hydroxide, carbonate, hydrogen carbonate , phosphoric acid-hydrogen salt, phosphate, condensed phosphate, metaphosphate (trimetaphosphate, tetrametaphosphate, hexametaphosphate), polyphosphate (tripolyphosphate, pyrophosphate), borate and metaborate except.)
(D) water (E) containing a trivalent or higher crosslinkable polyvalent metal salt compound,
A composition containing 2.5% by mass or more and 125% by mass or less of component (C) relative to component (A). The composition according to claim 1, wherein the total amount of component (C) is 0.1% by mass or more and 5% by mass or less. 3. The composition according to claim 1, wherein the component (C) is selected from inorganic salts or ammonium salts of alkali metals or alkaline earth metals. The composition according to any one of claims 1 to 3, wherein the component (C) is one or more selected from the group consisting of calcium chloride, potassium chloride, ammonium chloride and ammonium sulfate. A mixture obtained by adding and mixing 50 g of the soil improvement composition and 12 g of bentonite with a cation exchange capacity of 1 meq / 100 g in a 50 ml resin container was allowed to stand at 23 ° C. for 3 days. 5. Any one of claims 1 to 4, wherein the reaction rate of said vinyl-based unsaturated monomer calculated from the content of said vinyl-based unsaturated monomer as a free acid in the water extract is 90% or more. A composition according to claim 1. The composition according to any one of claims 1 to 5, wherein the pH is 5.5 or more and 7.0 or less. The composition according to any one of claims 1 to 6, which is for soil improvement having a cation exchange capacity of 0.3 meq/100 g or more. The composition according to any one of claims 1 to 7, wherein the total amount of component (A) is 1% by mass or more and 20% by mass or less. The composition according to any one of claims 1 to 8, wherein the total amount of component (E) is 0.1% by mass or more and 10% by mass or less, and is equal to or less than the total amount of component (A). The composition according to any one of claims 1 to 9, wherein the total amount of component (A) and component (E) is 3.0% by mass or more and 20% by mass or less. A kit for ground improvement,
a vinyl-based unsaturated monomer or a salt thereof;
a polymerization initiator;
Monovalent or divalent inorganic salts (however, aluminates, hydroxides, carbonates, hydrogen carbonates, phosphoric acid-hydrogen salts, phosphates, condensed phosphates, metaphosphoric acid (trimetaphosphoric acid, tetrametaphosphoric acid) , hexametaphosphate) salts, polyphosphate (tripolyphosphate, pyrophosphate) salts, borates and metaborates), and
a trivalent or higher crosslinkable polyvalent metal salt compound;
with
A kit comprising 2.5% by mass or more and 125% by mass or less of the monovalent or divalent inorganic salt with respect to the vinyl-based unsaturated monomer or salt thereof. A ground improvement method,
A method comprising the step of curing the soil improvement composition according to any one of claims 1 to 10 in the ground.