JP2019081876A - Ground improver composition and use thereof - Google Patents

Abstract

To provide a ground improver composition capable of providing excellent ground durability while suppressing corrosion of a metal structure, and to provide a use thereof.SOLUTION: The ground improver composition contains (A) a metal (meth)acrylate, (B) a polyvalent metal salt compound other than the metal (meth)acrylate, (C) an α-hydroxy acid or a salt thereof, (D) a basic compound, (E) a polymerization initiator, and (F) water. The total amount of the component (A) and the component (B) is 2.0-15 mass%. The molar ratio of the component (C) to a central metal of the component (B) is 0.1-1.0. The ground improver composition has a pH of 4.0-9.0. Preferably, the component (B) is an aluminum salt compound, and the component (C) is a C2-8 α-hydroxy acid or a salt thereof.SELECTED DRAWING: None

Description

  The present specification relates to a ground improver composition and its use.

  As a chemical | medical agent for ground injection which injects into a soft ground etc. and improves the said ground, the ground improvement agent of water glass type | system | group is well known conventionally, and the temporary reinforcement at the time of excavation work It is widely used for permanent purposes such as ground improvement.

  However, gel materials obtained from water glass ground improvers are pointed out as having problems in terms of durability. In addition, since the chemical solution contains a sulfuric acid component, there is a concern that the deterioration of a structure such as concrete can be promoted in the ground.

  As ground improvers other than water glass, acrylic ground improvers comprising an aqueous solution containing acrylate are mentioned. For example, Patent Document 1 discloses a composition for injection material containing monohydric or bivalent metal salt of (meth) acrylic acid, trivalent metal salt, oxidizing agent, two or more reducing agents having different reducing power, and water. The thing is described. Patent Document 2 discloses a (meth) acrylic acid-based chemical solution containing an aqueous solution of a monovalent or divalent metal salt of (meth) acrylic acid, an aqueous solution of an aluminum water-soluble salt, and an aqueous bisulfite solution. Patent Document 3 discloses a ground injection composition containing (meth) acrylic acid metal salt, a polyvalent metal salt compound other than the (meth) acrylic acid metal salt, an oxidizing agent, a specific reducing agent and water. ing.

JP 2001-241288 A JP, 2006-104795, A JP, 2016-130286, A

  According to the ground improvers disclosed in Patent Literatures 1 to 3 according to the present inventors, it was found that corrosion of a structure such as iron may be observed depending on the pH and other conditions of use. On the other hand, when an alkali is added to such a ground improver to suppress corrosion, precipitates are generated, and the gel strength is reduced due to the reduction of the crosslinking effect, and the permeability to the ground due to the precipitates is reduced, etc. It turned out that a problem would occur. The reduction of gel strength and permeability will reduce the durability of the improved ground. Furthermore, it turned out that such a defect becomes more remarkable when trying to improve an alkaline ground.

  The present specification provides a ground improver composition that can provide excellent ground durability while suppressing corrosion of a metal structure, and its use.

  MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, the present inventors acquired the knowledge that said subject could be solved by containing alpha hydroxy acid as an acryl-type ground improving agent. Based on these findings, the present specification provides the following means.

[1] It is a ground improving agent composition,
The following (A) to (F) components:
(A) (Meta) acrylic acid metal salt (B) Multivalent metal salt compound other than the above (meth) acrylic acid metal salt (C) α-hydroxy acid or salt thereof (D) basic compound (E) polymerization initiator ( F) contains water,
The total amount of the components (A) and (B) is 2.0% by mass or more and 15% by mass or less,
The molar ratio of the component (C) to the central metal of the component (B) is 0.1 or more and 1.0 or less,
Composition, whose pH is 4.0-9.0.
[2] The composition according to [1], wherein the component (B) is an aluminum salt compound.
[3] The composition according to [1] or [2], wherein the component (C) is an α-hydroxy acid having 2 to 8 carbon atoms or a salt thereof.
[4] It is a ground improvement method,
Introducing the ground improver composition according to any one of [1] to [3] into the ground,
A method comprising.
[5] The method according to [4], which is used in the injection solidification method.

  The present specification relates to a ground improver composition, a ground improvement method, and the like. According to the ground improver composition (hereinafter, also referred to simply as the present composition) disclosed in the present specification, it is derived from a polyvalent metal salt compound etc. by containing an alpha hydroxy acid even in the presence of an alkali The formation of precipitates can be suppressed, and excellent liquid stability can be exhibited. For this reason, the present composition can form a gel excellent in durability, exhibiting good permeability to the ground and gel strength. In addition, the present composition simultaneously has the ability to suppress deterioration of concrete in addition to good corrosion resistance to metal structures. Furthermore, since the composition exhibits good liquid stability even on alkaline ground, it can exhibit excellent permeability and gel strength. From these things, the present composition can be widely applied to various applications from temporary various ground reinforcement at the time of excavation work to permanent ground improvement such as various ground improvement.

  The ground improvement method (hereinafter, also referred to as the present method) and the like disclosed in the present specification can produce the same action as that by the present composition.

  In the present specification, “(meth) acrylic” means acrylic and / or methacrylic, and “(meth) acrylate” means acrylate and / or methacrylate.

  As used herein, "ground improvement agent" includes agents used for ground improvement for various purposes. Here, “ground improvement” is, for example, water leakage prevention, water shutoff, liquefaction suppression, ground reinforcement, etc., for example, as a method of construction, mountain tunnel method or its supporting method (pre-reception method, various reinforcement methods) A consolidation method, a water stop method, an injection solidification method (or a chemical solution injection method), a jet grout method etc. may be mentioned.

  Hereinafter, embodiments of the present composition, the present method and the like will be described in detail.

<Ground improvement agent composition>
The present composition comprises (A) component: (meth) acrylic acid metal salt, (B) component: polyvalent metal salt compound other than (meth) acrylic acid metal salt, (C) component: alpha hydroxy acid or a salt thereof, Component (D): basic compound, component (E): polymerization initiator, component (F): water can be contained.

<PH of the present composition>
The present composition preferably has a pH close to the neutral region, in consideration of the suppression of corrosion of the structure in the ground. The specific pH value is, for example, more than 3.5 and less than 10, and for example, 4.0 or more and less than 10. Favorable corrosion resistance can be ensured as it is this range. From the viewpoint of securing further preferable corrosion resistance, it is also, for example, 4.0 or more and 9.0 or less, and for example, 4.0 or more and 8.5 or less, and for example, 4.0 or more and 8 or more. It is 0 or less, for example, 5.0 or more and 8.0 or less, and for example, 5.5 or more and 7.0 or less.

<(A) Component: (Meth) Acrylate Metal Salt>
Examples of (meth) acrylic acid metal salts include alkali metal salts such as lithium salts, sodium salts and potassium salts of (meth) acrylic acid; alkaline earth metal salts such as calcium salts and barium salts; magnesium salts, aluminum salts And zirconium salts etc., and only one of these may be used alone, or two or more may be used in combination. Among these, calcium and magnesium salts are preferable as the metal salt from the viewpoint of obtaining a gel product having good strength and deformation resistance, and a magnesium salt is more preferable.

  In preparation of the present composition, metal (meth) acrylate is preferably used as an aqueous solution. The concentration at that time is not particularly limited, and can be appropriately set in a range where the (meth) acrylate does not precipitate, that is, in the range of 45 mass% or less close to saturation. In consideration of the concentration of the metal salt of (meth) acrylic acid in the present composition, for example, it is preferably 2% by mass or more, and particularly preferably 3% by mass or more in the case of an alkaline earth metal salt. Preferably it is 5 mass% or more. Further, the upper limit concentration thereof may be, for example, 40% by mass or less, for example, 35% by mass or less, and may be, for example, 30% by mass or less, and for example, 15% by mass or less can do.

  The concentration of the (meth) acrylic acid metal salt in the present composition is not particularly limited, but is, for example, preferably 0.5% by mass or more, and for example, 1.0% by mass or more, for example, 2.0% by mass % Or more, for example, 3.0% by mass or more. When the concentration of the (meth) acrylic acid metal salt is 0.5% by mass or more, the strength of the obtained gel product will be sufficient. In addition, the concentration of the (meth) acrylic acid metal salt is not particularly limited, but is, for example, 14.5% by mass or less, and for example, 14% by mass or less, and for example, 13% by mass or less For example, it is 12% by mass or less, for example, 10% by mass or less, and for example, 8.0% by mass or less, and for example, 5.0% by mass or less. If the concentration is 14.5 mass% or less, good permeability to the ground can be secured. The range of the concentration of the (meth) acrylic acid metal salt can be set by combining the lower limit concentration and the upper limit concentration, and is, for example, 0.5% by mass or more and 14.5% by mass or less. It is 1.0 mass% or more and 14 mass% or less, and can be 2.0 mass% or more and 12 mass% or less. In addition, the density | concentration of the (meth) acrylic-acid metal salt in this composition is prescribed | regulated also by the total amount with the density | concentration of the polyvalent metal salt compound mentioned later.

<(B) Component: Multivalent metal salt compound other than (meth) acrylic acid metal salt>
Examples of polyvalent metal salt compounds other than metal salts of (meth) acrylic acid (hereinafter, also simply referred to as the present polyvalent metal salt compounds) include divalent or trivalent or higher metal salt compounds, and the above (meth) compounds The compound except the acrylic acid metal salt (A) is mentioned. The divalent metal is not particularly limited, and examples thereof include magnesium, calcium and barium. The trivalent or higher metal is not particularly limited, and examples thereof include aluminum, zirconium, titanium and cerium. Of these, trivalent metal salt compounds are preferred in that the strength of the gel product obtained can be easily controlled. Specific compounds include, for example, aluminum chloride, aluminum nitrate, aluminum sulfate, alum, sodium alum, aluminum acetate, aluminum lactate, polyaluminum chloride (basic aluminum chloride), polysulfuric aluminum chloride (basic sulfuric acid aluminum chloride) And zirconium salts such as zirconium acetate, zirconium nitrate, zirconium chloride, zirconium lactate, zirconium carbonate, zirconium oxynitrate, zirconium oxyacetate, zirconium sulfate, zirconium oxysulfate, titanium chloride and cerium nitrate, among which aluminum salts are preferred. And zirconium salts are more preferred, and aluminum salts are more preferred. As the polyvalent metal salt compound of the present invention, only one such metal salt may be used alone, or two or more thereof may be used in combination.

  Although the concentration of the present polyvalent metal salt compound in the present composition is not particularly limited, the metal oxide contained in the present polyvalent metal salt compound, ie, the metal oxide corresponding to the present polyvalent metal salt compound For example, it is preferable that it is 0.5 mass% or more, for example, it is 1.0 mass% or more, for example, 2.5 mass% or more. When the concentration of the present polyvalent metal salt compound is 0.5% by mass or more, the strength of the obtained gel product will be sufficient. The concentration of the polyvalent metal salt compound is not particularly limited, but is preferably, for example, 14.5% by mass or less, for example, 13% by mass or less, and for example, 10% by mass or less It is. If the concentration of the polyvalent metal salt compound of the present invention is 14.5% by mass or less, good permeability to the ground can be secured. The range of the concentration of the (meth) acrylic acid metal salt can be set by combining the lower limit concentration and the upper limit concentration, and is, for example, 0.5% by mass or more and 14.5% by mass or less. It is 1.0 mass% or more and 13 mass% or less, and can be 2.5 mass% or more and 10 mass% or less.

<Total concentration of (A) component and (B) component>
Although the total concentration of the (meth) acrylic acid metal salt which is the component (A) and the polyvalent metal salt compound which is the component (B) in the present composition is not particularly limited, In consideration of the strength and the speed of the gelation reaction, for example, the content is preferably 2.0% by mass or more. The total concentration is also, for example, 3.0% by mass or more, and for example, 4.0% by mass or more, from the viewpoint of gelation rate of further preferable gel substances. It is 0 mass% or more. The total concentration is not particularly limited, but is preferably 15% by mass or less. The total concentration is also, for example, 12% by mass or less, for example, 10% by mass or less, for example, 8.0% by mass or less, and for example, 5.0% by mass or less. The range of the total concentration can be various concentration ranges obtained by combining the lower limit and the upper limit respectively, and is, for example, 2.0 mass% or more and 15 mass% or less, and for example, 3.0 mass % Or more and 12% by mass or less, and for example, 4.0% by mass or more and 10% by mass or less.

<(C) ingredient: alpha hydroxy acid or its salt>
The α-hydroxy acid is a compound having a carboxylic acid group and at least one hydroxyl group, and is a compound in which the hydroxyl group is bonded to the α-position of the carboxylic acid group. Two or more carboxylic acid groups may be provided. According to the alpha hydroxy acid, even in the presence of an alkali, it is possible to suppress the formation of a precipitate derived from an acrylic acid metal salt or the like. Although it does not specifically limit as alpha hydroxy acid, For example, C2-C8 alpha hydroxy acid is mentioned. If the number of carbons exceeds 8, the amount to be added will be required. The carbon number of the alpha hydroxy acid is also, for example, 2 or more and 6 or less, and for example, 4 or more and 6 or less.

  As such a hydroxy acid, for example, DL-lactic acid, glyceric acid, gluconic acid, pantoic acid, 2-hydroxybutyric acid, 2-hydroxyisobutyric acid, DL-mandelic acid, m-hydroxymandelic acid, leucine acid, citromalic acid, thaltron Acid, pantoic acid, α-phenyl lactic acid, benzylidene lactic acid, glycolic acid, benzyl acid, benzyl glycolic acid, quinic acid, 2-hydroxyvaleric acid, 2-hydroxyisovaleric acid, 2-hydroxycaproic acid, 2-hydroxyenantonic acid 2-hydroxycaprylic acid, α-hydroxyisocaprylic acid, 2-hydroxypelargonic acid, 2-hydroxycaprylic acid, 2-ethyl-2-hydroxybutyric acid, 2-hydroxy-2-methylbutyric acid, 2-ethyl-2-hydroxybutyric acid Hydroxy-3-methylbutanoic acid, 2-hydroxy-3, 3- Dimethyl butyric acid, 2-hydroxy-2,3-dimethylbutanoic acid, 2-hydroxy-2,3,3-trimethylbutanoic acid, 2-hydroxy-3-methylvaleric acid, 2-hydroxy-2-ethylpentanoic acid, 2 -Hydroxy-2-methylpentanoic acid, 2-hydroxy-2,4-dimethylvaleric acid, 2-hydroxy-2-propylpentanoic acid, 2-hydroxy-4-oxopentanoic acid, 2-hydroxy-4-methyl-3 -Oxopentanoic acid, α-hydroxyisocaproic acid, 2-hydroxy-2-methylhexanoic acid, 3-methyl-2-hydroxyhexanoic acid, 2-hydroxy-3-oxohexanoic acid, 2-hydroxy-4-oxohexane Acid, 2-hydroxy-5-oxohexanoic acid, 2-hydroxy-2-methylheptanoic acid, 3-methyl-2-hydroxy acid Heptanoic acid, 2-hydroxy-2-methyl octanoic acid, 3-hydroxy-4-methoxy mandelic acid, α-hydroxy acids are monocarboxylic acids such as 4-methoxy mandelic acid. Moreover, aliphatic alpha hydroxy acids, such as carboxylic acid more than bivalence, such as tartaric acid, a citric acid, an isocitric acid, and DL- malic acid, are mentioned. Among them, α-hydroxy acids which are divalent or higher carboxylic acids such as citric acid, isocitric acid and DL-malic acid are preferable.

  The alpha hydroxy acid may be in the form of a salt. For example, salts of alkali metals such as potassium and sodium may be used.

  The concentration of α-hydroxy acid in the present composition is not particularly limited, but the ratio (molar ratio) of the number of moles of α-hydroxy acid to the number of moles of central metal of the present polyvalent metal salt compound in the present composition is It can be 0.1 or more. It is because there exists a tendency for suppression of the precipitate derived from the polyvalent metal salt compound etc. by contact with an alkali as this molar ratio is less than 0.1 to become difficult. The same concentration is also, for example, 0.15 or more, or, for example, 0.20 or more, or, for example, 0.30 or more. The molar ratio is not particularly limited, but can be 1.0 or less. If it exceeds 1.0, the strength of the gel tends to decrease. The same concentration is also, for example, 0.90 or less, for example, 0.80 or less, and for example, 0.70 or less, or for example, 0.60 or less. The range of the same molar ratio can be various concentration ranges obtained by combining the lower limit and the upper limit respectively, and is, for example, 0.10 or more and 1.0 or less, or, for example, 0.15 or more. It is 90 or less, for example, 0.20 or more and 0.60 or less.

<(D) component: basic compound>
The basic compound is not particularly limited as long as it can change the liquidity of the aqueous medium to the alkali side, and one or more suitably selected from various organic basic compounds and inorganic basic compounds Can be used. For example, it is preferable to use an inorganic basic compound. For example, common alkali agents such as sodium hydroxide, potassium hydroxide, magnesium hydroxide and the like can be used.

  The concentration of the basic compound in the present composition is not particularly limited, but may be added so as to obtain a pH that can improve the corrosion resistance. In order to ensure corrosion resistance in the present composition, it is most effective to adjust the pH to a certain range. The concentration of the basic compound for adjusting to the preferred pH of the composition described above also varies depending on the type of the basic compound and the other components mixed. Therefore, the amount and concentration of the basic compound used in the present composition are defined in such a pH range, or defined as an effective amount for setting the pH range.

<(E) component: polymerization initiator>
As the polymerization initiator, various known polymerization initiators applied to (meth) acrylic acid can be used, which are added for polymerizing the (meth) acrylic acid metal salt in the present composition and the like. For example, a thermal initiator, a redox initiator, and the like can be appropriately used from the viewpoint of pot life time, control of hardening time from ground injection to hardening (gelation), and the like.

Thermal initiators generally degrade more slowly than redox initiators, and can have a pot life of up to several days, for example. As a thermal initiator, for example, an azo compound can be used. As an example of an azo compound, 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-cyanovaleroic acid) and the like can be mentioned.
Among these, 2,2′-azobis [2- (imidazolin-2-yl) propane] and 2,2′-azobis [2- (imidazolin-2-yl) propane] from the viewpoint of obtaining an appropriate pot life. Dihydrochloride is preferred.

  The redox initiator generally decomposes faster than the thermal initiator, can maintain a pot life in the range of, for example, about 1 minute to 10 hours, and has a higher radical generation rate than the thermal initiator. The effects of oxygen inhibition can be reduced. The oxidizing agent and reducing agent used as a redox type initiator will be described.

(Oxidant)
The oxidizing agent is not particularly limited, and any known oxidizing agent can be used. Specifically, examples of inorganic oxidizing agents include sodium percarbonate, sodium perborate, sodium peroxide, calcium peroxide, peroxides such as barium peroxide and hydrogen peroxide, and sodium persulfate and persulfate Inorganic persulfate compounds such as potassium and ammonium persulfate may be mentioned, and only one of them may be used alone, or two or more may be used in combination.

  Examples of organic oxidizing agents include diacylperoxide, peroxydicarbonate, peroxyester, tetramethylbutylperoxyneodecanoate, bis (4-butylcyclohexyl) peroxydicarbonate, di (2 -Ethylhexyl) peroxy carbonate, butyl peroxy neodecanoate, dipropyl peroxy dicarbonate, diisopropyl peroxy dicarbonate, diethoxyethyl peroxy dicarbonate, diethoxyhexyl peroxy dicarbonate, hexyl Peroxydicarbonate, Dimethoxybutylperoxydicarbonate, Bis (3-methoxy-3-methoxybutyl) peroxydicarbonate, Dibutylperoxydicarbonate, Dicetylperoxydicarbonate, Dimyristyl Peroxydicarbonate, 1,1,3,3-tetramethylbutylperoxypivalate, hexylperoxypivalate, butylperoxypivalate, trimethylhexanoylperoxide, dimethylhydroxybutylperoxyneodecadeca Noate, amyl peroxy neodecanoate, butyl peroxy neo decanoate, t-butyl peroxy neoheptanoate, amyl peroxy pivalate, t-butyl peroxy pivalate, t- In addition to amylperoxy-2-ethylhexanoate, laurylperoxide, dilauroylperoxide, and didecaylperoxide, t-butyl hydroperoxide, p-cumyl hydroperoxide, t-amyl hydroperoxide, 1,1,3, 3-Tetramethylbutyl hydroperoxide etc Hydroperoxides, percarboxylic acids such as peracetic acid and perbenzoic acid, methyl ethyl ketone peroxide or benzoyl peroxide (benzoyl peroxide), etc. may be mentioned, and only one of them may be used alone or two. The above 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 Preferred are ketone peroxides, percarboxylic acids such as peracetic acid and perbenzoic acid, and diacyl peroxides such as benzoyl peroxide. Organic oxidizing agents such as organic peroxides are preferable to inorganic oxidizing agents in that they tend to increase the reaction rate in the ground.

(Reductant)
There is no particular limitation as a reducing agent, and known reducing agents can be used. Specific compounds include thiosulfate compounds such as sodium thiosulfate and potassium thiosulfate, bisulfite compounds such as sodium bisulfite and potassium bisulfite, hypophosphorous compounds such as sodium hyposulfite and potassium hyposulfite, Sulfite compounds such as sodium sulfite and potassium sulfite, sodium hydroxymethanesulfinate (long gallite), sodium ascorbate, sodium erythorbate, ferrous salt, ferrous salt, thiourea, copper sulfate, and diethanolamine, triethanolamine, hydrazine, hydroxylamine And amines such as dimethylaminopropionitrile, dimethylaminopropanol, piperazine and morpholine. One of these reducing agents may be used alone, or two or more thereof may be used in combination.

  The concentration and amount of the polymerization initiator used should take into consideration the type and concentration of metal salt of (meth) acrylic acid, the type and concentration of polyvalent metal salt compound, pH, conditions such as water temperature, and setting values such as curing time. It may be appropriately selected depending on the application of the composition. 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 thermal initiator in the present composition can be, for example, about 1 mM or more and 200 mM or less. The concentration of the oxidant of the redox initiator in the present composition can be, for example, about 0.1 mM to 100 mM, and the concentration of the reducing agent in the present composition is, for example, 0.1 mM to 100 mM The degree can be.

<(F) ingredient: water>
The composition contains water. The composition is applied to the ground or the like in the form of an aqueous solution or a suspension. In the present composition, water can dissolve or disperse various components, and can function as a transport medium or the like of these components to the ground. Water can also function as a pot life time adjustment agent. In addition, this composition can contain the organic solvent which melt | dissolves and disperse | distributes the above-mentioned various components other than water in the range which does not impair the effect of this composition.

  The water in the present composition generally corresponds to the remainder excluding the components (A) to (E) in the present composition, and the other components described later optionally contained. The concentration in the present composition is, for example, 50% by mass or more, for example, 60% by mass, and for example, 70% by mass or more, and can be, for example, 80% by mass or more.

<Other ingredients>
The composition can contain various components as long as the effect of the composition is not impaired. For example, other ground improvers such as known water glasses can also be included. In addition, known corrosion inhibitors such as quaternary ammonium salts, organic acid amine salts, aromatic compounds, nitrites, alcohols, hexamethylenetetramine, etc., silicones, mineral oils, vegetable oils, higher alcohols, etc. One or more selected from a foaming agent, a known emulsifying agent, a known metal sealing agent and the like can be appropriately contained.

  Moreover, this composition can contain vinyl-type monomers other than a (meth) acrylic acid metal salt. The vinyl-based monomer used in combination may be either an ionic monomer (anionic monomer or cationic monomer) or a nonionic monomer, and these may be used in combination. As the anionic monomer, (meth) acrylic acid; itaconic acid, itaconic acid monoalkyl ester, maleic acid, maleic acid monoalkyl ester, fumaric acid, fumaric acid monoalkyl ester, citraconic acid, citraconic acid monoalkyl ester, Carboxyl group-containing monomers such as cinnamic acid, itaconic anhydride and maleic anhydride and salts or anhydrides thereof; 2-acrylamido-2-methylpropane sulfonic acid, vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, styrene Sulfonic acid, polyoxyalkylene mono (meth) acrylate sulfuric acid, 2-hydroxyethyl (meth) acryloyl phosphate, phenyl-2-acryloyl oxyethyl phosphate, 2-acryloyl oxyalkyl phosphonic acid and salts thereof (alkali metal , Alkaline earth metal salts, ammonium salts), and the like. These monomers may be used alone or in combination of two or more.

  As the cationic monomer, tertiary amino group-containing compounds such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide and salts thereof; (Meth) acryloyloxyethyl trimethyl ammonium chloride, (meth) acryloyl oxyethyl dimethyl benzyl ammonium chloride, (meth) acryloyl amino propyl trimethyl ammonium chloride, (meth) acryloyl amino propyl dimethyl benzyl ammonium chloride, (meth) acryloyl oxy 2-hydroxy A quaternary ammonium base-containing compound such as propyltrimethyl ammonium chloride can be used. These monomers may be used alone or in combination of two or more.

  As the non-ionic monomer, (meth) acrylamide, dimethyl acrylamide, diethyl acrylamide, isopropyl acrylamide, hydroxyethyl acrylamide, vinyl pyrrolidone, vinyl formamide, vinyl acetamide, (meth) acrylic acid 2-hydroxyethyl, polyoxyalkylene Mono (meth) acrylate, polyoxyalkylene alkyl allyl ether, glycerin monoallyl ether etc. are mentioned. These monomers may be used alone or in combination of two or more.

  In the present composition, water-soluble divinyl monomers such as polyethylene glycol di (meth) acrylate, methylene bis acrylamide and hydroxy ethylene bis acrylamide, in order to improve the strength, dimensional stability and durability of the obtained gel product, And a crosslinking agent such as N-methylol acrylamide can be blended. The content of these crosslinking agents can be, for example, 30% by mass or less, and for example, 20% by mass or less, with respect to the (meth) acrylic acid metal salt, from the viewpoint of the effect.

  Moreover, in order to increase or reinforce the present composition, an aggregate may be blended as needed. As the aggregate, powders such as cement, fly ash, diatomaceous earth, calcium carbonate, kaolin, clay, bentonite, perlite, calcite, blast furnace slag, gypsum, silica sand, pulp and carbon powder, various fibers and the like can be used. . Since the aggregate may reduce the flowability of the composition and the bending strength of the gel if the amount used is too large, it is preferably at most 10 times the mass of the metal (meth) acrylate. When the aggregate precipitates in the composition, it is preferable to use an anti-settling agent and the like together.

<Use of the present composition>
In this composition, a polymerization reaction proceeds with a polymerization initiator to form a gel. Therefore, the present composition containing a polymerization initiator can be used as it is to be injected into the ground and gelated in the ground. According to the present composition, although it contains the basic compound which is the component (D) for preventing corrosion of the structure etc., it contains the alpha hydroxy acid which is the component (C). By suppressing the formation of precipitates derived from polyvalent metal salt compounds and the like, the inherent permeability of the present composition can be secured, and a strong gel can be formed in the ground. In addition, the present composition is suitable for suppressing deterioration of concrete based on its liquid property. The present composition can solve the problems in the acrylic acid-based ground improver at once.

  Furthermore, in the present composition, the ground on which the present composition is introduced by injection or the like is an alkaline ground, and the composition itself has good liquid stability even in an alkaline environment such as being exposed to alkaline groundwater. It exhibits good solution stability and can ensure good permeability and gel strength. Therefore, the composition can be suitably used for the improvement of various grounds.

<Kit for ground improvement>
By providing the components (A) to (E) described above, a kit for ground improvement (hereinafter, also referred to as the present kit) can be obtained. According to this kit, at the time of use (when used), these components can be mixed and / or dissolved with water which is the component (F) of the present composition to prepare the present composition. After preparation of the composition, various properties of the composition can be exhibited. The kit can also include water, which is the component (F).

  Since this kit is provided with the (alpha) hydroxy acid which is the component (C), even if it is in the presence of the basic compound (alkali) which is the component (D), the polyvalent metal salt compound etc. which is the component (B) The present composition can be prepared which can suppress the formation of precipitates derived from the above and improve the liquid stability.

  In addition, since the present kit comprises the components (A) to (E) for preparation at the time of use, the present composition can be easily used while securing a sufficient working time. That is, the present kit can overcome the problems resulting from initiation of polymerization simultaneously with preparation because the composition contains the component (E); the polymerization initiator. According to the present kit, it is possible to solve problems concerning production, distribution, storage, etc. and a short pot life in ground improvement work etc.

  The present kit can take a kit mode in which the component (E) does not act on the component (A) in a separated manner. That is, besides the separation aspect of various components for preventing the reaction of the (A) component and the (E) component, the form for realizing such separation is not particularly limited. For example, as a form for separation, various components may be separated into two or more packages, or various components may be separated into one package having two or more compartments or storage areas. .

  In addition, before ground injection, the present composition may be prepared from the kit and injected into the ground through the injection pipe, or one or more components of the kit may be separately injected into the injection pipe. The composition may be prepared by injection and mixing within the injection tube.

  The following table exemplifies some examples of the two-part kit of the combination of each component in the kit. In the following table, "o" indicates that it is contained, "x" indicates that it is not contained, and "o / x" indicates that it may or may not be contained. Further, in (a) of the table, the (E) component indicates a component which acts as an initiator with one agent such as a thermal initiator, and in the (b) to (d), the (E1) component and the (E2) component are The component which acts as an initiator with two agents, such as an oxidant of a redox initiator and the reducing agent, is shown.

  As shown in the above table, if component (A) and component (E) or component (E1) + (E2) are separated so that polymerization is not initiated, components (B) and (C) will be separated. It is apparent that the components (D) and (D) can be kitted in various manners. Moreover, although it was set as the kit which consists of 2 agents in the said table | surface, as long as it is a combination which a polymerization start is suppressed or avoided, it can also divide | segment into 3 or more agents. Furthermore, water as the component (F) can be contained in any of these agents, or can be prepared as a separate agent.

  The content of each of the components (A) to (E) in the kit is not particularly limited. At the time of preparation, the required amount of each component may be measured, or it may be measured in advance to have a concentration or pH suitable for the present composition. In addition, it may be divided into fixed amounts so that the required amount can be easily measured.

  In the kit, for example, when the molar ratio of the component (C) to the central metal of the component (B) of the composition to be prepared is 0.1 or more and 1.0 or less, the component (B) and (C) It is preferable to measure etc. beforehand so that it may become the said molar ratio with a component.

  Further, the component (A), the component (B), the component (C), the component (D) and the component (E) may be appropriately in the form of a solution or may be itself (powder, liquid, etc.). It is appropriately selected according to the handleability, stability and physical properties of each component.

<Ground improvement method>
The ground improvement method disclosed herein may comprise an introducing step of introducing the composition into the ground. According to this method, it is possible to obtain an improved ground excellent in corrosion resistance and the like while securing the permeability of the present composition to secure the strength and durability of the gel substance.

  This method is applicable to various ground improvement as described above. As a specific construction method, the various construction methods already described can be mentioned. The introduction step of the present composition in the present method can be carried out by injecting the present composition into the ground in a known manner according to the application and method of application. Generally, the ground or the like is supplied to the ground by mixing one or more liquids to be injected, separately or in the injection pipe or the like, through the injection pipe disposed in the ground, using a pump or the like. Introduce.

  This method is suitable for the injection solidification method (chemical liquid injection method). In the injection / solidification method (chemical solution injection method), the present composition is infiltrated into the sand ground, and the water present in the gap between the sand ground is replaced with the injection agent, and then the injection agent is gelled to bind the sand. It is a ground improvement method that has functions such as water leakage prevention, water blocking, liquefaction prevention, and ground reinforcement. This method is a method of injecting a chemical solution from the injection pipe to a necessary place using a relatively small-scale apparatus and solidifying it. For example, it is effective for preventing liquefaction of the ground directly under the existing structures such as tanks and piers. Ground improvement method. Since this composition is excellent in the permeability to the ground and has a suitable working life, it can exhibit excellent performance when applied to a pouring / solidification method (chemical solution pouring method).

Hereinafter, the present invention will be specifically described based on examples. The present invention is not limited by these examples. In the following, “parts” and “%” mean parts by mass and% by mass unless otherwise specified.

Below, the evaluation method of a ground improving agent composition is described, and each Example etc. are described after that.
[1] pH of the composition
It measured with pH meter.
[2] Appearance of Composition The composition was visually observed.
[3] Curing time (gel time)
After preparing each composition under the conditions of room temperature (25 ° C.), the solution was immediately filled with a 9 cc glass bottle, covered and allowed to stand. After that, since the water-insoluble gel starts to precipitate when curing starts, the time from when it is visually added to the glass bottle to when white turbidity starts is taken as the curing time.
[4] Uniaxial Compressive Strength 92 g of each composition was placed in a plastic mold, and 298 g of sand (Toyoura sand) was added little by little to prepare a sand + composition mixture. Then, it was allowed to stand still for 3 days or more, completely cured and taken out, and a test body (sand gel) of 9050 mm × H85 to 90 mm was produced. When the composition contained water glass, the same test sample was prepared after standing for 28 days. The test body was compressed at 1 mm / min with a compression tester (Instron 5566) to measure the load. The value obtained by dividing the maximum value of the load by the cross-sectional area of the test body was taken as the compressive strength (unit: kN / m ² ).

[5] Durability (flowing water)
Place the sand gel prepared in [4] in a water tank, add water saturated with calcium carbonate (water imitating groundwater flow) until the whole sand gel is immersed, and circulate water at a flow rate of 1.5 L / min. The sample was allowed to stand for up to 80 days while replacing the water in the water tank at intervals of about 3 days to 1 week, and the sand gel was taken out at regular intervals and the weight was measured. Moreover, the volume was calculated based on the weight, and the volume retention was calculated. When a clear volume reduction (1 vol% or more) was observed, it was regarded as x.
Volume retention% = (sand gel volume after test) / (sand gel volume before test) x 100

[6] Permeability Permeability was evaluated for ordinary sand and alkaline sand containing 0.55 wt% of calcium carbonate relative to sand. In addition to permeability for alkaline sand, compressive strength of hardened material was also measured. Specifically, it was carried out as follows.

(Preparation of normal sand ground)
In a 20 L tin can, 8450 g of water was added, and 25410 g of No. 7 silica sand was gradually introduced to prepare a water-saturated ground. The dimensions of the ground were approximately Φ 280 mm × H 250 mm. In preparation of the ground, a pipe for injecting a composition was fixed in advance to a tin can and buried in the ground. The outlet of the pipe was adjusted to be 13 cm high from the bottom of the tin can.
(Preparation of alkaline sand ground)
No. 7 silica sand 2540 g and calcium carbonate 13 g were mixed in a plastic bag, and a total of 10 bags of this mixed sand were prepared. Put 845g of water into a 20L tin can and gradually add one bag of the above mixed sand. This was repeated 10 times to produce an alkaline sand ground. Piping for composition injection was embedded in the same manner as described above.

(Penetration evaluation)
The inside of the piping for composition injection was filled with water, and connected to a stainless steel pressure-resistant vessel (volume 2 L).
The high pressure air introduction piping with a ball valve, the composition discharge piping, and the pressure purge piping are connected to the above-mentioned pressure resistant container, and the high pressure air introduction piping further includes a regulator and a precision pressure gauge. There is. Also, the container is placed on an electronic balance, and the amount of injected composition can be measured by weight reduction. 1100 g of the composition was placed in the above-mentioned pressure resistant container, the gage pressure in the container was set to 3 kPa, the injection was started, and the test was terminated when 1000 g was injected. The time required to complete the test was measured, and the average permeation rate (g / min) was calculated.
Average penetration rate = 1000 ÷ (time required to finish the test min)

(Compression strength evaluation)
After pouring, place the tin can (containing alkaline sand) in the room, and let the composition stand for 3 days or more (28 days in the case of a water glass-containing composition) to cure completely. The material was taken out, and a Φ50 mm × H85-90 mm sand gel was cut out using a trimmer. Using this as a test body, uniaxial compressive strength was measured according to [4].

[7] Liquefaction strength ratio The liquefaction strength ratio (RL20) was measured in accordance with JGS 0541 (repetitive non-drainage triaxial test method of soil). Specifically, it was carried out as follows.
A sand gel of 5050 mm × H100 mm was prepared by the same method as the uniaxial compressive strength test, and used as a test body. The specimen was isotropically consolidated in a triaxial tester, and then undrained, and repeatedly loaded with a sine wave with a frequency of 0.1 Hz at a restraint pressure of 100 kN / m ² . This test was carried out a plurality of times while changing the axial difference stress, and the number of loading times to liquefy was determined for each stress. From the regression curve of the above-mentioned test, axial difference stress and RL20 which lead to liquefaction with 20 loadings were computed. The determination of liquefaction was made when the both amplitude distortion of the test sample exceeded 5% due to repeated loading.

  In general, sand gels break the bonds between sand particles in repeated loading, and strain increases with the number of loadings. RL20 is a value obtained by dividing the axial differential stress (σ) leading to liquefaction after loading 20 times by the effective confining pressure (σ′c), but the larger the value, the larger the liquefaction strength. In addition, since RL20 required by the actual liquefaction measures is about 0.4-1.0, it does not determine a value about the high intensity | strength thing over 1.0, but all "1. It is written as "0".

[8] Iron corrosive storage Sand gel embedded with iron material is stored at 60 ° C. Corrosive strength was compared by the weight loss rate of iron material due to corrosion. Specifically, it carried out as follows. A 15 × 50 × 2 mm steel material (SS400) was embedded in a 110 cc glass bottle, and a sand gel was produced according to [4]. In addition, the position which embeds steel materials was made constant (a position where the steel materials lower end is 25 mm from the bottom of a bottle) with all the samples. After storing the test body at 60 ° C., the steel material was taken out at regular intervals, the sand and rust were removed with a steel brush, dried and the weight was measured, and the weight reduction rate was calculated.
Weight reduction rate% = (Steel weight before test-Steel weight after test) / (Steel weight before test) x 100

Examples 1 to 14 and Comparative Examples 1 to 7
To 21.0 g of water, add 18.4 g (2.0%) of an aqueous solution of polyaluminum chloride at 10% concentration in Al ₂ O ₃ conversion, and 10.5 g (4.0%) of an aqueous solution of magnesium acrylate at a concentration of 35%. Dissolve by adding 2.4 g (2.6%) of acid. While stirring and mixing this solution, 20.4 g (2.5%) of an aqueous sodium hydroxide solution having a concentration of 11.2% was gradually added to adjust the solution pH to 7. Subsequently, 0.19 g (equivalent to 9 mM) of peroxodisulfate ammonium salt (APS) was added and dissolved, and further 19.2 g (equivalent to 40 mM) of sodium thiosulfate aqueous solution having a concentration of 3.0% was added to improve the ground improver of Example 1 It was a composition.

  Examples 2 to 14 and Comparative Examples 1 to 7 are Component (A): (Meth) Acrylate Metal Salt, (B) Component: Multivalent Metal Salt Compound, (C) Component: α-Hydroxy Acid, (D) Component Basic compound, component (E): A ground improver composition was prepared in the same manner as in Example 1 except that the polymerization initiator was used as shown in Table 2 below.

  In Examples 2 to 14 and Comparative Examples 2 to 5 and 7, pH was adjusted as described in Table 2 using NaOH which is a basic compound.

  In Example 6, 2,2'-bis (2-imidazolin-2-yl) [2,2'-azobispropane] dihydrochloride instead of ammonium peroxodisulfate and 3.0% aqueous sodium thiosulfate solution 19.4 g of a 1.4% aqueous solution of

  In Example 7, 19.4 g of a 0.4% aqueous solution of tert-butyl hydroperoxide was added instead of ammonium peroxodisulfate.

  In Example 8, instead of the 3.0% aqueous sodium thiosulfate solution, 19.4 g of a 0.57% aqueous solution of sodium hydroxymethanesulfinate was added.

  In Example 9, 19.4 g of a 2.1% aqueous solution of thiourea dioxide was added instead of the 3.0% aqueous sodium thiosulfate solution.

  In Example 10, 3.2% of malic acid was used instead of citric acid.

In Example 11, 18.4 g (ZrO ₂ equivalent: 4.0%) of a 20% aqueous solution of zirconium acetate was added instead of the 10% aqueous solution of polyaluminum chloride, and 2.9 g (3.2%) of citric acid was added. Was used. In Example 12, 17.9 g of a 20% aqueous solution of zirconium acetate (in terms of ZrO ₂ : 3.9%) was added instead of the 10% aqueous solution of polyaluminum chloride to make gluconic acid 1.0% as an alpha hydroxy acid. .

  In Comparative Example 1, water was added in place of citric acid.

  In Comparative Example 2, 2.4% of propanetricarboxylic acid (PTCA) was added in place of citric acid. In Comparative Example 3, water was added in place of the α-hydroxy acid. In Comparative Example 6, citric acid was changed to trisodium citrate 2.6%, and no pH adjuster was added.

  The evaluation results of Examples 1 to 14 and Comparative Examples 1 to 7 are collectively shown in Table 2.

The following supplements the description in the table.
AAMg: magnesium acrylate PAC: polyaluminum chloride αHA: α hydroxy acid APS: peroxodisulfate ammonium salt azo: 2,2′-bis (2-imidazolin-2-yl) [2,2′-azobispropane] · 2 hydrochloride PBH: tert-butyl hydroperoxide Ron Garitto: hydroxymethanesulfinic acid sodium citrate Na: trisodium citrate * 1: the terms of ZrO _2.
* 2: PTCA (propane tricarboxylic acid)
* 3: Evaluation not possible due to foaming due to calcium carbonate

  As shown in Table 2, Examples 1 to 14 all have the properties (curing time, compressive strength, durability, permeability, permeability under alkali, strength under alkali, liquefaction strength, iron corrosion). It was excellent.

  On the other hand, reference is made to comparative examples 1 to 7. Comparative Example 1 is derived from the fact that α hydroxy acid is not used and the composition pH is low, and the iron material corrodes relatively violently, and in alkaline ground, calcium carbonate and acid react with each other to foam, and this air bubbles Since the sand ground was pierced and reached the surface, almost all the mixed liquid injected flows out to the ground surface along the path where air bubbles passed. For this reason, the intended ground improvement could not be done.

  Comparative Example 2 is an example using propanetricarboxylic acid in place of citric acid as the alpha hydroxy acid, and Comparative Example 3 is an example of non-use of alpha hydroxy acid, but all are adjusted to pH 7 with NaOH. Precipitation occurred in the process and it became impossible to evaluate.

  In Comparative Example 4, the molar ratio of α-hydroxy acid was low, and precipitation occurred in the process of adjusting the pH to 7 with NaOH, making evaluation impossible. It was found that Comparative Example 5 had a tendency that the compressive strength and the liquefaction strength ratio were less likely to occur because the molar ratio of the α-hydroxy acid was high.

  In Comparative Example 6, since the pH was as low as 3.5, foaming and the like under an alkali occurred, and in Comparative Example 7, after adjusting the pH to 10, it became impossible to evaluate due to precipitation.

  From the above, the compositions of Examples 1 to 14 include (A) component, (B) component, (C) component α hydroxy acid, and (E) component, and have a pH within a predetermined range. Therefore, the formation of precipitates and the like is suppressed, the liquid stability is improved, and the permeability is excellent, and the curing time and the compressive strength are also as intended based on the compositions of the respective examples. I understood it.

  Further, in Examples 1 to 14, the permeability to alkaline sand ground and the ground strength after injection to the ground can be sufficiently ensured, and the composition contains the (C) component α-hydroxy acid. While suppressing formation of the precipitate in itself and ensuring permeability and gel strength, the liquid stability is maintained even when the composition is in an alkaline environment, and excellent permeability and intended gel strength are exhibited. I found that I could do it.

  Moreover, according to the results of Examples 1 to 14 and Comparative Examples 1 to 7, it was also found that various curing initiators can be used for the present composition to set the curing time. Furthermore, α-hydroxy acids include trivalent carboxylic acids such as citric acid (C6), divalent carboxylic acids such as malic acid (C4), and monovalent carboxylic acids such as gluconic acid (C6). It turned out that the effect can be exhibited even if various alpha hydroxy acids are used.

  Further, according to the results of Examples 1 to 14 and Comparative Examples 1 to 7, good characteristics are easily obtained when the pH is more than 3.5 or 4 or more, and good when the pH is less than 10 or 9 or 8 or less. It was also found that it was easy to obtain various characteristics.

  Further, according to the results of Examples 1 to 14 and Comparative Examples 1 to 7, the molar ratio of α-hydroxy acid to polyvalent metal salt compound is the amount of metal salt of (meth) acrylic acid which is the component (A) There is a tendency that good characteristics can be obtained by appropriately setting according to the amount of the initiator, etc., and it is easy to easily obtain good characteristics in the range of 0.1 or more and 1.0 or less. The

  Further, according to the results of Examples 1 to 14 and Comparative Examples 1 to 7, the content and total amount of the metal salt of (meth) acrylic acid which is the component (A) and the polyvalent metal salt compound which is the component (B) are Can be set appropriately according to the gel strength to be obtained, etc., and in a simple manner, good characteristics can be obtained by setting it to 2% or more and 15% or less, 2% or more and 10% or less, etc. It turned out that there is a tendency.

  This composition is excellent in the permeability to the ground, and is capable of obtaining a gel having good deformation resistance and durability. For this reason, it is useful as an injection agent composition for ground liquefaction prevention. Moreover, application to the ground agent for preventing ground liquefaction according to the present invention by the injection solidification method (chemical solution injection method) is useful for the ground immediately below the existing non-movable structure.

Claims (5)

A ground improver composition,
The following (A) to (F) components:
(A) (Meta) acrylic acid metal salt (B) Multivalent metal salt compound other than the above (meth) acrylic acid metal salt (C) α-hydroxy acid or salt thereof (D) basic compound (E) polymerization initiator ( F) contains water,
The total amount of the components (A) and (B) is 2.0% by mass or more and 15% by mass or less,
The molar ratio of the component (C) to the central metal of the component (B) is 0.1 or more and 1.0 or less,
Composition, whose pH is 4.0-9.0.   The composition according to claim 1, wherein the component (B) is an aluminum salt compound.   The composition according to claim 1, wherein the component (C) is an α-hydroxy acid having 2 to 8 carbon atoms or a salt thereof. Ground improvement method,
Introducing the ground improver composition according to any one of claims 1 to 3 into the ground;
A method comprising.   The method according to claim 4, which is used for a pouring solidification method.