JP6916712B2 - Ground improver composition and its use - Google Patents

Description

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

Waterglass-based ground improvement agents have long been well known as ground injection agents that inject into soft ground to improve the ground, and are used for temporary reinforcement during excavation work to improve building structures. It is widely used for permanent purposes such as ground improvement.

However, it has been pointed out that the gel product obtained from the water glass-based ground improving agent has a problem in terms of durability. In addition, since the chemical solution contains a sulfuric acid component, there is a concern that it may accelerate the deterioration of structures such as concrete in the ground.

Examples of the ground improver other than the water glass type include an acrylic ground improver composed of an aqueous solution containing an acrylate salt. For example, Patent Document 1 describes a composition for an 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. The thing is listed. Patent Document 2 discloses a (meth) acrylic acid-based chemical solution containing a monovalent or divalent metal salt aqueous solution of (meth) acrylic acid, an aqueous solution of an aluminum water-soluble salt, and an aqueous solution of bisulfite. Patent Document 3 discloses a ground injection composition containing a (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.

Japanese Unexamined Patent Publication No. 2001-241288 Japanese Unexamined Patent Publication No. 2006-104795 Japanese Unexamined Patent Publication No. 2016-130286

According to the present inventors, it has been found that in the ground improving agents disclosed in Patent Documents 1 to 3, corrosion of structures 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 improving agent to suppress corrosion, precipitates are generated, which reduces the cross-linking effect, resulting in a decrease in gel strength, a decrease in permeability to the ground due to the precipitates, and the like. It turns out that a problem arises. Decreased gel strength and permeability will reduce the durability of the improved ground. Furthermore, it was found that these defects became even more prominent when trying to improve the alkaline ground.

The present specification provides a ground improver composition capable of providing excellent ground durability while suppressing corrosion of a metal structure and its use.

As a result of diligent studies to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by containing α-hydroxy acids as an acrylic ground improving agent. Based on these findings, the present specification provides the following means.

[1] A ground improving agent composition, which is
The following components (A) to (F):
(A) (Meta) Acrylic Acid Metal Salt (B) Polyvalent Metal Salt Compound other than the (Meta) Acrylic Acid Metal Salt (C) α-Hydroxy Acid or a 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.
A composition having a pH of 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] This is a ground improvement method.
A step of introducing the ground improving agent composition according to any one of [1] to [3] into the ground.
A method.
[5] The method according to [4] used in the injection solidification method.

The present specification relates to a ground improving agent composition, a ground improving method, and the like. According to the ground conditioner composition disclosed in the present specification (hereinafter, also simply referred to as the present composition), it is derived from a polyvalent metal salt compound or the like by containing an α-hydroxy acid even in the presence of an alkali. The formation of precipitates is suppressed, and excellent liquid stability can be exhibited. Therefore, the present composition can form a gel having excellent durability by exhibiting good permeability to the ground and gel strength. At the same time, the present composition has good corrosion resistance to metal structures and the ability to suppress deterioration of concrete. Furthermore, since the present composition exhibits good liquid stability even in alkaline ground, it can exhibit excellent permeability and gel strength. From these facts, this composition can be widely applied to various uses from temporary various ground reinforcements during excavation work to permanent ground improvement such as various ground improvements.

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

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

As used herein, the term "ground improving agent" includes agents used for ground improving for various purposes. Here, "ground improvement" includes, for example, prevention of water leakage, water stoppage, liquefaction suppression, and ground strengthening. For example, as a construction method, a mountain tunnel construction method or its auxiliary construction method (preceding construction method, various reinforcement construction methods), ground. Examples include the consolidation method, the water stop method, the injection solidification method (or the chemical injection method), and the jet grout method.

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

<Ground improver composition>
In this composition, (A) component: (meth) acrylic acid metal salt, (B) component: a polyvalent metal salt compound other than (meth) acrylic acid metal salt, (C) component: α-hydroxy acid or a salt thereof, The component (D): a basic compound, the component (E): a polymerization initiator, and the component (F): water can be contained.

<pH of this composition>
The composition preferably has a pH close to the neutral region in consideration of suppressing corrosion of structures in the ground. Specific pH values are, for example, more than 3.5 and less than 10, and for example, 4.0 or more and less than 10. Within this range, good corrosion resistance can be ensured. From the viewpoint of ensuring more suitable corrosion resistance, for example, it is 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 8.0. 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) acrylic acid metal salt>
Examples of the (meth) acrylic acid metal salt include alkali metal salts such as lithium salt, sodium salt and potassium salt of (meth) acrylic acid; alkaline earth metal salts such as calcium salt and barium salt; magnesium salt and aluminum salt. , Zirconium salt and the like, and only one of these may be used alone, or two or more thereof may be used in combination. Among these, calcium salt and magnesium salt are preferable as the type of metal salt, and magnesium salt is more preferable, in that a gel having good strength and deformation resistance can be obtained.

In preparing the present composition, the (meth) acrylic acid metal salt is preferably used as an aqueous solution. The concentration at that time is not particularly limited, and can be appropriately set within a range in which (meth) acrylate does not precipitate, that is, a concentration of 45% by mass or less, which is close to saturation. Considering the concentration of the (meth) acrylic acid metal salt 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. It is preferably 5% by mass or more. The upper limit concentration can be, for example, 40% by mass or less, 35% by mass or less, 30% by mass or less, and 15% by mass or less. can do.

The concentration of the (meth) acrylic acid metal salt in the composition is not particularly limited, but is preferably 0.5% by mass or more, for example 1.0% by mass or more, or 2.0% by mass, for example. % 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 is sufficient. The concentration of the (meth) acrylic acid metal salt is not particularly limited, but is, for example, 14.5% by mass or less, for example, 14% by mass or less, and for example, 13% by mass or less. Yes, for example, 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. When the same concentration is 14.5% by mass or less, good permeability to the ground can be ensured. The range of the concentration of the (meth) acrylic acid metal salt can be set by combining these lower limit concentration and upper limit concentration, and is, for example, 0.5% by mass or more and 14.5% by mass or less, and for example, for example. It can be 1.0% by mass or more and 14% by mass or less, and 2.0% by mass or more and 12% by mass or less. The concentration of the (meth) acrylic acid metal salt in the present composition is also defined by the total amount with the concentration of the polyvalent metal salt compound described later.

<Component (B): Polyvalent metal salt compound other than (meth) acrylic acid metal salt>
The polyvalent metal salt compound other than the (meth) acrylic acid metal salt (hereinafter, also simply referred to as the present polyvalent metal salt compound) is a divalent or trivalent or higher metal salt compound, and the above (meth). Examples thereof include compounds other than the acrylic acid metal salt (A). The divalent metal is not particularly limited, and examples thereof include magnesium, calcium, and barium. The trivalent or higher valent metal is not particularly limited, and examples thereof include aluminum, zirconium, titanium, and cerium. Among these, a trivalent metal salt compound is preferable from the viewpoint that the strength of the obtained gel 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), polyaluminum sulfate (basic aluminum chloride). , Zirconium acetate, zirconium nitrate, zirconium chloride, zirconium lactate, zirconium carbonate, zirconium oxynitrate, zirconium oxyacetate, zirconium sulfate, zirconium oxysulfate and other zirconium salts, titanium chloride and cerium nitrate. And zirconium salts are more preferred, and aluminum salts are even more preferred. As the polyvalent metal salt compound, only one of these metal salts may be used alone, or two or more of them may be used in combination.

The concentration of the polyvalent metal salt compound in the composition is not particularly limited, but the oxide of the metal contained in the polyvalent metal salt compound, that is, the metal oxide corresponding to the polyvalent metal salt compound. In terms of conversion, it is preferably, for example, 0.5% by mass or more, and for example, 1.0% by mass or more, and for example, 2.5% by mass or more. When the concentration of the polyvalent metal salt compound is 0.5% by mass or more, the strength of the obtained gel is sufficient. The concentration of the polyvalent metal salt compound is not particularly limited, but is preferably 14.5% by mass or less, for example, 13% by mass or less, and 10% by mass or less, for example. Is. When the concentration of the polyvalent metal salt compound is 14.5% by mass or less, good permeability to the ground can be ensured. The range of the concentration of the (meth) acrylic acid metal salt can be set by combining these lower limit concentration and upper limit concentration, and is, for example, 0.5% by mass or more and 14.5% by mass or less, and for example, for example. It is 1.0% by mass or more and 13% by mass or less, and can be 2.5% by mass or more and 10% by mass or less.

<Total concentration of component (A) and component (B)>
The total concentration of the (meth) acrylic acid metal salt as the component (A) and the polyvalent metal salt compound as the component (B) in the present composition is not particularly limited, but the obtained gel product is not particularly limited. Considering the strength and the speed of the gelation reaction, for example, it is preferably 2.0% by mass or more. From the viewpoint of the gelation rate of the more suitable gel strength, the total concentration is also, for example, 3.0% by mass or more, for example, 4.0% by mass or more, and for example, 5. It is 0% by 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, and 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 these lower and upper limits, respectively, and is, for example, 2.0% by mass or more and 15% by mass or less, and for example, 3.0% by mass. % Or more and 12% by mass or less, and for example, 4.0% by mass or more and 10% by mass or less.

<Component (C): α-hydroxy acid or salt thereof>
The α-hydroxy acid is a compound having a carboxylic acid group and at least one hydroxyl group, and 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 α-hydroxy acid, the formation of precipitates derived from acrylic acid-based metal salts and the like can be suppressed even in the presence of alkali. The α-hydroxy acid is not particularly limited, and examples thereof include α-hydroxy acids having 2 or more and 8 or less carbon atoms. This is because if the number of carbon atoms exceeds 8, an addition amount is required. The number of carbon atoms of the α-hydroxy acid is, for example, 2 or more and 6 or less, and for example, 4 or more and 6 or less.

Examples of such α-caproic acid include DL-lactic acid, glyceric acid, gluconic acid, enanthic acid, 2-hydroxybutyric acid, 2-hydroxyisobutyric acid, DL-mandelic acid, m-hydroxymandelic acid, leucic acid, citramalic acid, and the like. Tartronic acid, pantoic acid, α-phenyllactic acid, benziliden lactic acid, glycolic acid, benzylic acid, benzylglycolic acid, quinic acid, 2-hydroxycaproic acid, 2-hydroxyisovaleric acid, 2-hydroxycaproic acid, 2-hydroxyenanthic acid Acid, 2-hydroxycaproic acid, α-hydroxyisocaproic acid, 2-hydroxypelargonic acid, 2-hydroxycaproic acid, 2-ethyl-2-hydroxybutyric acid, 2-hydroxy-2-methylbutyric acid, 2-ethyl-2 -Hydroxy-3-methylbutanoic acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-2,3-dimethylbutanoic acid, 2-hydroxy-2,3,3-trimethylbutanoic acid, 2-hydroxy-3 -Methylenanthic acid, 2-hydroxy-2-ethylpentanoic acid, 2-hydroxy-2-methylpentanoic acid, 2-hydroxy-2,4-dimethylenanthic acid, 2-hydroxy-2-propylpentanoic acid, 2-hydroxy -4-oxopentanoic acid, 2-hydroxy-4-methyl-3-oxopentanoic acid, α-hydroxyisocaproic acid, 2-hydroxy-2-methylcaproic acid, 3-methyl-2-hydroxycaproic acid, 2- Hydroxy-3-oxocaproic acid, 2-hydroxy-4-oxocaproic acid, 2-hydroxy-5-oxocaproic acid, 2-hydroxy-2-methylenanthic acid, 3-methyl-2-hydroxyheptanic acid, 2- Examples thereof include α-hydroxylic acid, which is a monovalent carboxylic acid such as hydroxy-2-methyloctanoic acid, 3-hydroxy-4-methoxymandelic acid, and 4-methoxymandelic acid. Examples thereof include aliphatic α-hydroxy acids such as divalent or higher carboxylic acids such as tartaric acid, citric acid, isocitric acid and DL-malic acid. Of these, α-hydroxy acids, which are divalent or higher carboxylic acids such as citric acid, isocitric acid, and DL-malic acid, are preferable.

The α-hydroxy acid may be in the form of a salt. For example, it may be a salt of an alkali metal such as potassium or sodium.

The concentration of the α-hydroxy acid in the present composition is not particularly limited, but the ratio (molar ratio) of the number of moles of the α-hydroxy acid to the number of moles of the central metal of the present polyvalent metal salt compound in the present composition is defined. It can be 0.1 or more. This is because if the molar ratio is less than 0.1, it tends to be difficult to suppress precipitates derived from polyvalent metal salt compounds and the like by contact with alkali. The same concentration is also, for example, 0.15 or more, for example, 0.20 or more, and for example, 0.30 or more. The molar ratio is not particularly limited, but can be 1.0 or less. This is because 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, and for example, 0.60 or less. The range of the same molar ratio can be various concentration ranges obtained by combining these lower and upper limits, respectively, and is, for example, 0.10 or more and 1.0 or less, and for example, 0.15 or more and 0. It is 90 or less, and for example, 0.20 or more and 0.60 or less.

<Component (D): Basic compound>
The basic compound is not particularly limited as long as it can change the liquid property of the aqueous medium to the alkaline side, and is one or more appropriately 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, general alkaline 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 capable of improving corrosion resistance. In order to ensure corrosion resistance in this composition, it is most effective to adjust the pH within a certain range. The concentration of the basic compound for adjusting to a suitable pH of the present composition described above also varies depending on the type of the basic compound and 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 as an effective amount for setting in such a pH range.

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

The heat initiator generally decomposes more slowly than the redox-based initiator, and the pot life can be secured, for example, up to several days. As the heat initiator, for example, an azo compound can be used. Examples of azo compounds 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-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] are easy to obtain an appropriate pot life. Dihydrochloride is preferred.

Redox-based initiators generally decompose faster than heat initiators, can secure a pot life in the range of, for example, about 1 minute to 10 hours, and have a higher radical generation rate than heat initiators. The effect of oxygen inhibition can be reduced. Oxidizing agents and reducing agents used as redox-based initiators will be described.

(Oxidant)
The oxidizing agent is not particularly limited, and a known oxidizing agent can be used. Specifically, examples of the inorganic oxidizing agent include sodium peroxide, sodium perborate, sodium peroxide, calcium peroxide, barium peroxide, hydrogen peroxide and other peroxides, and sodium peroxide 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 thereof may be used in combination.

Examples of the organic oxidizing agent include diacyl peroxide, peroxydicarbonate, peroxyester, tetramethylbutylperoxyneodecanoate, bis (4-butylcyclohexyl) peroxydicarbonate, and di (2). -Ethylhexyl) Peroxycarbonate, butylperoxyneodecanoate, dipropylperoxydicarbonate, diisopropylperoxydicarbonate, diethoxyethylperoxydicarbonate, diethoxyhexylperoxydicarbonate, hexyl Peroxydicarbonate, dimethoxybutylperoxydicarbonate, bis (3-methoxy-3-methoxybutyl) peroxydicarbonate, dibutylperoxydicarbonate, disetylperoxydicarbonate, dimyristylperoxydi Carbonate, 1,1,3,3-tetramethylbutylperoxypivarate, hexylperoxypivalate, butylperoxypivarate, trimethylhexanoyl peroxide, dimethylhydroxybutylperoxyneodecanoate, Amyl Peroxy Neodecanoate, Butyl Peroxy Neodecanoate, t-Butyl Peroxy Neoheptanoate, Amyl Peroxy Pivalate, t-Butyl Peroxy Pivalate, t-Amil Peroxy -2-Ethylhexanoate, lauryl peroxide, dilauroyl peroxide, didecyl peroxide, t-butyl hydroperoxide, p-cumyl hydroperoxide, t-amyl hydroperoxide, 1,1,3,3-tetra Hydroperoxides such as methylbutyl hydroperoxide, 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. Alternatively, two or more kinds 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, methyl ethyl ketone peroxide and the like. Ketone peroxides, percarboxylic acids such as peracetic acid and perbenzoic acid, and diacyl peroxides such as benzoyl peroxide are preferred. Organic oxidizing agents such as organic peroxides are preferable in that they tend to increase the reaction rate in the ground more easily than inorganic oxidizing agents.

(Reducing agent)
The reducing agent is not particularly limited, and a known reducing agent can be used. Specific compounds include thiosulfate compounds such as sodium thiosulfate and potassium thiosulfate, bisulfate compounds such as sodium bisulfate and potassium bisulfate, hypophosphate compounds such as sodium hyposulfate and potassium hyposulfate, and the like. Sulfate compounds such as sodium sulfite and potassium sulfite, sodium hydroxymethanesulfinate (longalit), sodium ascorbate, sodium erythorbinate, ferrous salt, thiourea, copper sulfate, and diethanolamine, triethanolamine, hydrazine, hydroxylamine. , Dimethylaminopropionitrile, dimethylaminopropanol, amines such as piperazine and morpholin, and the like. These reducing agents may be used alone or in combination of two or more.

The concentration and amount of the polymerization initiator should be determined in consideration of the type and concentration of the (meth) acrylic acid metal salt, the type and concentration of the polyvalent metal salt compound, the conditions such as pH and water temperature, and the set values such as the curing time. It may be appropriately selected depending on the intended use of the composition. Further, in the case of a redox-based initiator, a combination of an oxidizing agent and a reducing agent can be appropriately selected.

The concentration of the heat initiator in the present composition can be, for example, about 1 mM or more and 200 mM or less. Further, the concentration of the redox-based initiator in the present composition of the oxidizing agent can be, for example, about 0.1 mM or more and 100 mM or less, and the concentration of the reducing agent in the present composition is, for example, 0.1 mM or more and 100 mM or less. Can be a degree.

<(F) component: water>
The composition contains water. This 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 function as a transport medium for these components to the ground. In addition, water can also function as an adjusting agent for pot life and the like. In addition to water, the composition may contain an organic solvent that dissolves and disperses the various components described above, as long as the effects of the composition are not impaired.

The water in the composition generally corresponds to the residue excluding the components (A) to (E) in the composition and other components described below, which are contained as necessary. The concentration in the composition can be, for example, 50% by mass or more, for example, 60% by mass, for example, 70% by mass or more, and for example, 80% by mass or more.

<Other ingredients>
The composition may contain various components as long as the effects of the composition are not impaired. For example, other ground improving agents such as known water glass can also be included. Also, known rust preventives such as quaternary ammonium salts, organic acid amine salts, aromatic compounds, nitrites, alcohols, hexamethylenetetramines, and known defoamers such as silicone-based, mineral oil-based, vegetable oil-based, and higher alcohol-based defoamers. One or more selected from foaming agents, known emulsifiers, known metal encapsulants and the like can be appropriately contained.

In addition, the present composition may contain a vinyl-based monomer other than the (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 anionic monomers, (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-acrylamide-2-methylpropanesulfonic acid, vinylsulfonic acid, allylsulfonic acid, metallicylsulfonic acid, styrene. Sulfonic acid, polyoxyalkylene mono (meth) acrylate sulfate, 2-hydroxyethyl (meth) acryloyl phosphate, phenyl-2-acryloyloxyethyl phosphate, 2-acryloyloxyalkylphosphonic acid and salts thereof (alkali metal salt, alkaline soil) Kind metal salts, ammonium salts) and the like. These monomers may be used alone or in combination of two or more.

Examples of the cationic monomer include tertiary amino group-containing compounds such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide and salts thereof; (Meta) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyloxyethyldimethylbenzylammonium chloride, (meth) acryloylaminopropyltrimethylammonium chloride, (meth) acryloylaminopropyldimethylbenzylammonium chloride, (meth) acryloyloxy2-hydroxy A quaternary ammonium base-containing compound such as propyltrimethylammonium chloride can be used. These monomers may be used alone or in combination of two or more.

Nonionic monomers include (meth) acrylamide, dimethylacrylamide, diethylacrylamide, isopropylacrylamide, hydroxyethylacrylamide, vinylpyrrolidone, vinylformamide, vinylacetamide, (meth) acrylate-2-hydroxyethyl, and polyoxyalkylene. Examples thereof include mono (meth) acrylate, polyoxyalkylene alkylallyl ether, and glycerin monoallyl ether. These monomers may be used alone or in combination of two or more.

In this composition, in order to improve the strength, dimensional stability and durability of the obtained gel, water-soluble divinyl monomers such as polyethylene glycol di (meth) acrylate, methylene bisacrylamide and hydroxyethylene bisacrylamide, etc. Alternatively, a cross-linking agent such as N-methylolacrylamide may be blended. From the viewpoint of its effect, the content of these cross-linking agents can be, for example, 30% by mass or less, and for example, 20% by mass or less, based on the (meth) acrylic acid metal salt.

In addition, an aggregate can be added as needed to increase or reinforce the composition. As the aggregate, cement, fly ash, diatomaceous earth, calcium carbonate, kaolin, clay, bentonite, pearlite, vermiculite, blast furnace slag, gypsum, silica sand, powder such as pulp and carbon powder, and various fibers can be used. .. If the amount of aggregate used is too large, the fluidity of the composition and the bending strength of the gel may be reduced. Therefore, the mass of the aggregate is preferably 10 times or less the mass of the (meth) acrylic acid metal salt. When the aggregate is settled in the composition, it is preferable to use a settling inhibitor or the like in combination.

<Use of this composition>
In this composition, the polymerization reaction proceeds by the polymerization initiator to produce a gel product. Therefore, the present composition containing the polymerization initiator can be directly injected into the ground and used for gelation in the ground. According to this composition, although it contains a basic compound which is a component (D) for suppressing corrosion of a structure, it contains α-hydroxyic acid which is a component (C). , The formation of precipitates derived from polyvalent metal salt compounds and the like can be suppressed, the original permeability of the present composition can be ensured, and a strong gel can be formed in the ground. Further, the present composition is suitable for suppressing deterioration of concrete based on its liquid property. This composition can solve the problems of acrylic acid-based ground improving agents at once.

Further, in this composition, the ground into which the composition is introduced by injection or the like is alkaline ground, and the composition itself has good liquid stability even in an alkaline environment such as exposure to alkaline groundwater. As well as exhibiting good liquid stability, good permeability and gel strength can be ensured. Therefore, this composition can be suitably used for improving various grounds.

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

Since this kit contains α-hydroxy acid, which is a component (C), even in the presence of a basic compound (alkali), which is a component (D), a polyvalent metal salt compound, etc., which is a component (B), etc. It is possible to prepare the present composition having improved liquid stability by suppressing the formation of precipitates derived from.

In addition, since this kit contains the components (A) to (E) for preparation at the time of use, the composition can be easily used with a sufficient pot life. That is, this kit can overcome the problem caused by the fact that the composition contains the component (E); the polymerization initiator, so that the polymerization is started at the same time as the preparation. According to this kit, problems related to manufacturing, distribution, storage, etc., short pot life in ground improvement work, etc. can be solved.

This kit can be provided separately in a manner in which the component (E) does not act on the component (A). That is, in addition to the separation mode of various components for not reacting the component (A) and the component (E), 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. ..

Alternatively, the composition may be prepared from the kit and injected into the ground via an injection tube prior to ground injection, 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 an injection tube.

The table below exemplifies some examples of this kit consisting of two agents regarding the mode of combination of each component in this kit. In the following table, "○" indicates that it is contained, "x" indicates that it is not contained, and "○ / ×" indicates that it may or may not be contained. Further, in (a) of the table, the component (E) indicates a component that acts as an initiator with one agent such as a heat initiator, and in the same (b) to (c), the components (E1) and (E2) are , A component that acts as an initiator with two agents such as an oxidizing agent and a reducing agent of a redox-based initiator is shown.

As shown in the above table, if the component (A) and the component (E) or the component (E1) + (E2) are separated so as not to initiate polymerization, the component (B) and the component (C) are separated. And, it is clear that the component (D) is made into a kit in various ways. Further, in the above table, the kit is composed of two agents, but it can be divided into three or more agents as long as the combination is such that the initiation of polymerization is suppressed or avoided. Further, 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 component (A) to (E) in this kit is not particularly limited. At the time of preparation, the required amount of each component may be weighed, or it may be weighed in advance so as to have a concentration and pH suitable for the present composition. In addition, it may be subdivided into fixed amounts so that the required amount can be easily measured.

In this kit, for example, when the molar ratio of the component (C) to the central metal of the component (B) to be prepared is 0.1 or more and 1.0 or less, the component (B) and the component (C) ) It is preferable that the components are weighed in advance so as to have the molar ratio.

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

<Ground improvement method>
The ground improvement method disclosed herein can include an introduction step of introducing the composition into the ground. According to this method, it is possible to obtain an improved ground having excellent corrosion resistance and the like while ensuring the permeability of the present composition and ensuring the strength and durability of the gel product.

This method can be applied to various ground improvements described above. Specific construction methods include various construction methods already described. The step of introducing the composition in this method can be carried out by injecting the composition into the ground in a known manner according to the application and construction method. Generally, by pumping or the like, one or more kinds of liquids to be injected are pumped to the ground through an injection pipe arranged in the ground, separately or while being mixed in the injection pipe or the like. Introduce.

This method is suitable for the injection solidification method (chemical injection method). In the injection solidification method (chemical injection method), the composition is permeated into the sand ground, the water existing in the gaps of the sand ground is replaced with the injection agent, and then the injection agent gels to bind the sand ground. It is a ground improvement method that has functions such as water leakage prevention, water stoppage, liquefaction prevention, and ground strengthening. It is a method of injecting a chemical solution from an injection pipe to a required place and solidifying it using a relatively small-scale device. It is a ground improvement method. Since this composition has excellent permeability to the ground and has an appropriate pot life, it can exhibit excellent performance when applied to the injection solidification method (chemical injection method).

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

The evaluation method of the ground improving agent composition will be described below, and then each example and the like will be described.
[1] pH of the composition
It was measured with a pH meter.
[2] Appearance of the composition The composition was visually observed.
[3] Curing time (gel time)
After preparing each composition under the condition of room temperature (25 ° C.), the mixture was immediately filled with a 9 cc glass bottle, covered with a lid, and allowed to stand. After that, when the curing started, the water-insoluble gel started to precipitate, so the time from the visual addition to the glass bottle to the start of cloudiness was defined 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 for 3 days or more to be completely cured and taken out to prepare a test body (sand gel) having a diameter of 50 mm and a size of H85 to 90 mm. When the composition contained water glass, the same test piece was prepared after standing for 28 days. This test piece was compressed at 1 mm / min with a compression tester (Type 5566 manufactured by Instron), and the load was measured. The value obtained by dividing the maximum value of the load by the cross-sectional area of the test piece was taken as the compressive strength (unit: kN / m ² ).

[5] Durability (running water)
The sand gel prepared in [4] is allowed to stand in a water tank, water saturated with calcium carbonate (water imitating a groundwater flow) is added to a height at which the entire sand gel is immersed, and water is circulated at a flow rate of 1.5 L / min. Then, the water in the aquarium was replaced every 3 days to 1 week and left for a maximum of 80 days, and the sand gel was taken out and weighed at regular intervals. In addition, the volume was calculated based on the weight, and the volume retention rate was calculated. Those in which a clear volume reduction (1 vol% or more) was observed were marked with x.
Volume retention% = (Sandgel volume after test) ÷ (Sandgel volume before test) x 100

[6] Permeability Evaluation of permeability was carried out for normal sand ground and alkaline sand ground containing 0.55 wt% of calcium carbonate with respect to sand. For alkaline sand ground, in addition to permeability, the compressive strength of the cured product was also measured. Specifically, it was carried out as follows.

(Preparation of normal sand ground)
8450 g of water was put into a 20 L tin can, and 25410 g of No. 7 silica sand was gradually added to prepare a water-saturated ground. The dimensions of the ground were approximately Φ280 mm × H250 mm. In preparing the ground, a pipe for injecting the composition was fixed to a tin can in advance and buried in the ground. The discharge port of the pipe was adjusted so that the height was 13 cm from the bottom of the tin can.
(Preparation of alkaline sand ground)
2540 g of No. 7 silica sand and 13 g of calcium carbonate were mixed in a plastic bag, and a total of 10 bags of this mixed sand were prepared. Put 845 g of water in a 20 L tin can and gradually add 1 bag of the above mixed sand. This was repeated 10 times to prepare an alkaline sand ground. The pipe for injecting the composition was buried by the same method as described above.

(Permeability evaluation)
The inside of the composition injection pipe was filled with water and connected to a stainless steel pressure-resistant container (capacity 2 L).
A high-pressure air introduction pipe equipped with a ball valve, a composition discharge pipe, and a pressure purge pipe are connected to the pressure-resistant container, and the high-pressure air introduction pipe is further equipped with a regulator and a precision pressure gauge. There is. In addition, the container is installed on an electronic balance, and the injection amount of the composition can be measured by weight reduction. 1100 g of the composition was placed in the pressure-resistant container, the gauge pressure in the container was set to 3 kPa, 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 complete the test min)

(Compressive strength evaluation)
After the injection is completed, the tin can (containing alkaline sand ground) is allowed to stand indoors, and the composition is allowed to stand for 3 days or more (28 days in the case of a water glass-containing composition) to be completely cured and then cured. An object was taken out, and a sand gel of Φ50 mm × H85-90 mm was cut out using a trimmer. Using this as a test piece, the uniaxial compressive strength was measured according to [4].

[7] Liquefaction strength ratio The liquefaction strength ratio (RL20) was measured according to JGS 0541 (soil repeated non-drainage triaxial test method). Specifically, it was carried out as follows.
A sand gel of Φ50 mm × H100 mm was prepared by the same method as the uniaxial compressive strength test, and used as a test body. The test piece was isotropically compacted with a triaxial test device, then put into a non-drained state, and repeatedly loaded with a sine wave having a frequency of 0.1 Hz at ^{a restraining pressure of 100 kN / m 2.} This test was carried out a plurality of times with different axial stresses, and the number of loadings leading to liquefaction was determined for each stress. From the regression curve of the above test, the axial stress and RL20 leading to liquefaction after 20 loadings were calculated. The determination of liquefaction was made when both amplitude strains of the test piece exceeded 5% due to repeated loading.

In general, in sand gel, the bond between sand particles is broken by repeated loading, and the strain increases according to the number of loadings. RL20 is a non-dimensional value obtained by dividing the axial stress (σ) that leads to liquefaction after 20 loadings by the effective restraining pressure (σ'c), and the larger this value, the higher the liquefaction strength. Since the RL20 required for actual liquefaction countermeasures is about 0.4 to 1.0, the value is not fixed for those with high strength exceeding 1.0, and all of them are described in "1. It was written as "0".

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

<Examples 1, 3 to 14 , Comparative Examples 1 to 8 >
To 21.0 g of water, _{18.4 g (2.0%) of an aqueous solution of polyaluminum chloride having a concentration of 10% in terms of Al 2} O _{3 and} 10.5 g (4.0%) of an aqueous solution of magnesium acrylate having a concentration of 35% were added, and further citrate was added. 2.4 g (2.6%) of acid was added and dissolved. 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 pH of the solution to 7. Next, 0.19 g (equivalent to 9 mM) of ammonium peroxodisulfate salt (APS) was added to dissolve it, and 19.2 g (equivalent to 40 mM) of an aqueous sodium thiosulfate solution having a concentration of 3.0% was further added to improve the ground of Example 1. It was used as a composition.

In Examples 3 to 14 and Comparative Examples 1 to 8 , (A) component: (meth) acrylic acid metal salt, (B) component: polyvalent metal salt compound, (C) component: α-hydroxy acid, (D) component. : Basic compound, component (E): A ground improver composition was prepared by carrying out the same operation as in Example 1 except that the polymerization initiator was used as shown in Table 2 below.

In Examples 3 to 14 , Comparative Examples 2 to 5 and 7 to 8 , the pH was adjusted as shown in Table 2 using NaOH, which is a basic compound.

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

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

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

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

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

_{In Example 11, 18.4 g (ZrO 2} conversion: 4.0%) of a 20% zirconium acetate aqueous solution was added instead of the 10% polyaluminum chloride aqueous solution, and 2.9 g (3.2%) of citric acid was added. ) Was used. _{In Example 12, 17.9 g (ZrO 2} conversion: 3.9%) of a 20% zirconium acetate aqueous solution was added instead of the 10% polyaluminum chloride aqueous solution to obtain 1.0% gluconic acid as the α-hydroxy acid. ..

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

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

The evaluation results of Examples 1 , 3 to 14 and Comparative Examples 1 to 8 are also shown in Table 2.

The following is a supplement to the description in the table.
AAMg: Magnesium acrylate PAC: Polyaluminum chloride αHA: α-hydroxy acid APS: Peroxo disulfinate ammonium salt Azo: 2,2'-bis (2-imidazolin-2-yl) [2,2'-azobispropane], 2 Hydrochloride PBH: tert-butyl hydroperoxide Longarit: Sodium hydroxymethanesulfinate Na citrate: Trisodium citrate * 1: ZrO ₂ conversion.
* 2: PTCA (propanetricarboxylic acid)
* 3: Cannot be evaluated due to foaming derived from calcium carbonate

As shown in Table 2 , all of Examples 1, 3 to 14 have the characteristics (curing time, compressive strength, durability, permeability, permeability under alkali, strength under alkali, liquefaction strength, iron corrosiveness). ) Was excellent.

On the other hand, Comparative Examples 1 to 8 are referred to. Comparative Example 1 is derived from the fact that α-hydroxy acid is not used and the pH of the composition is low, so that the iron material corrodes relatively violently, and in alkaline ground, calcium carbonate reacts with the acid to foam, and these bubbles are formed. Since it broke through the sandy ground and reached the surface, almost all of the injected compound liquid flowed out to the ground surface along the path through which the bubbles passed. Therefore, the intended ground improvement could not be achieved.

Comparative Example 2 is an example in which a propantricarboxylic acid is used instead of citric acid as the α-hydroxy acid, and Comparative Example 3 is an example in which α-hydroxy acid is not used, but the pH is adjusted to 7 with NaOH in each case. Precipitation occurred in the process, making it impossible to evaluate.

In Comparative Example 4, the molar ratio of α-hydroxy acids was low, and precipitation occurred in the process of adjusting the pH to 7 with NaOH, making it impossible to evaluate. In Comparative Example 5, it was found that the compressive strength and the liquefaction strength ratio tended to be difficult to obtain 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 under alkaline conditions 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 and 3 to 14 contain the component (A), the component (B), the α-hydroxy acid which is the component (C), and the component (E), and have a pH in a predetermined range. Since it is provided, the formation of precipitates and the like is suppressed, the liquid stability is improved, the permeability is excellent, and the curing time and compressive strength are as intended based on the composition of each example. It turned out that.

Further, in Examples 1 , 3 to 14 , the permeability to the alkaline sand ground and the ground strength after injection into the ground are sufficiently secured, and by containing α-hydroxyic acid which is the component (C), Permeability and gel strength can be ensured by suppressing the formation of precipitates in the composition itself, and liquid stability is maintained even when the composition is in an alkaline environment to achieve excellent permeability and intended gel strength. Was found to be able to express.

Further, according to the results of Examples 1 , 3 to 14 and Comparative Examples 1 to 8 , it was also found that the curing time of the composition can be set by using various polymerization initiators. Further, α-hydroxy acids include trivalent carboxylic acids such as citric acid (6 carbon atoms), divalent carboxylic acids such as malic acid (4 carbon atoms), and monovalent carboxylic acids such as gluconic acid (6 carbon atoms). It was found that the action can be exhibited even if various α-hydroxy acids are used.

Further, according to the results of Examples 1 , 3 to 14 and Comparative Examples 1 to 8 , good characteristics are likely to be obtained when the pH is more than 3.5 or 4 or more, and when the pH is less than 10 or 9 or 8 or less. It was also found that it is easy to obtain the good characteristics of.

Further, according to the results of Examples 1 , 3 to 14 and Comparative Examples 1 to 8 , the molar ratio of α-hydroxy acid to the polyvalent metal salt compound is the amount of (meth) acrylic acid metal salt which is the component (A). , Good characteristics tend to be obtained by appropriately setting according to the amount of the polymerization initiator, etc., and simply, good characteristics tend to be obtained in the range of 0.30 or more and 1.0 or less. I understood.

Further, according to the results of Examples 1 , 3 to 14 and Comparative Examples 1 to 8 , the content of the (meth) acrylic acid metal salt as the component (A) and the polyvalent metal salt compound as the component (B) and The total amount can be appropriately set according to the gel strength to be obtained, etc., and simply, by setting it to 2% or more and 15% or less, 2% or more and 10% or less, good characteristics can be obtained. It turns out that it tends to be obtained.

This composition has excellent permeability to the ground, and it is possible to obtain a gel having good deformation resistance and durability. Therefore, it is useful as an injection composition for preventing ground liquefaction. Further, it is useful to apply the injection composition for preventing ground liquefaction of the present invention by the injection solidification method (chemical injection method) to the ground directly under the existing structure that cannot be moved.

Claims (6)

A ground conditioner composition,
The following components (A) to (F):
(A) (Meta) Acrylic Acid Metal Salt (B) Polyvalent Metal Salt Compound other than the (Meta) Acrylic Acid Metal Salt (C) α-Hydroxy Acid or a 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 0.3 or more and 1.0 or less.
A composition having a pH of 4.0-9.0. The composition according to claim 1, wherein the component (B) is 0.5% by mass or more and 14.5% by mass or less . The composition according to claim 1, wherein the component (B) is an aluminum salt compound. The composition according to claim 1 or 2, wherein the component (C) is an α-hydroxy acid having 2 to 8 carbon atoms or a salt thereof. It ’s a ground improvement method.
A step of introducing the ground improving agent composition according to any one of claims 1 to 3 into the ground.
A method. The method according to claim 5 , which is used in the injection solidification method.