JP2004244625A - Agent for treating wet soil and method for granulating wet soil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an agent for treating wet soil, capable of treating the wet soil having high moisture content with a small amount of the agent, and to provide a method for granulating the highly wet soil. <P>SOLUTION: The agent for treating wet soil contains as constituents (a) a water-soluble polymer and (b) gypsum having 0.11-1.63 m<SP>2</SP>/cm<SP>3</SP>specific surface, wherein (a) water-soluble polymer preferably contains carboxy group (including carboxylic acid salt group) and /or sulfonic acid group (including sulfonic acid salt group) and, more preferably, contains carboxy group and 0.5-50 mol% sulfonic acid-containing unit based on 100 mol% total constituent units. The method for granulating the wet soil comprises mixing the wet soil with the agent for treating wet soil. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a treating agent and a granulating method for modifying a hydrous soil so that it can be reused as a backfill material or the like as a substitute for sand or the like. The treating agent and the granulating method of the present invention can be applied to a water-containing soil having a high water content and an extremely low viscosity.

  Of the soil generated during construction work, such as soil generated during excavation work, water may flow into the excavation area and be discharged to the outside as sludge.Since such sludge has a high water content, They cannot even be transported by ordinary trucks or dump trucks, and cannot be used as backfill materials. For this reason, the mud is subjected to a dehydration treatment, a solidification treatment, or the like, so that the mud can be transported.

  However, even if a dehydration treatment is performed, it is necessary to make further appropriate improvements in order to perform the above-mentioned reuse, and in the case of performing a solidification treatment, what to do with the obtained solidified soil, Therefore, there was a problem that there was not much disposal place of solidified soil corresponding to the amount of generated mud.

  From such a point of view, studies have been made to convert wet soil such as mud into a granular material such as smooth sand and use it as a backfill material. As a granulation method, for example, there is a method in which a carboxyl group-containing water-soluble polymer powder is added and mixed, and then lime is added and mixed, followed by curing and granulation (Patent Document 1). Further, as a technique for solving the problem that the carboxyl group-containing water-soluble polymer powder is hardly soluble in hydrous soil, there is a method of granulating using a water-soluble polymer containing a carboxyl group and a sulfone group (Patent Documents) 2). This Patent Document 2 also discloses a method of using a hydraulic substance such as cement, quicklime, gypsum, etc. in order to increase the strength of a water-containing soil (granular soil) granulated using the water-soluble polymer. Further, Patent Document 3 discloses a method in which a copolymer of acrylamide and acrylic acid and sodium alginate are mixed with mud and granulated.

Each of the above-mentioned prior arts has its own characteristics and exerts a certain effect.However, in order to apply to a mud having a high water content and a low viscosity, it may not be said that it has sufficient treatment performance. For example, in many cases, a large amount of a treating agent such as the above-mentioned water-soluble polymer is required.
JP-A-6-17052 JP 2000-136383 A JP-A-10-152682

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a hydrous soil treatment agent and a method for granulating hydrous soil that can be used in a small amount even with hydrous soil having a high water content. .

The hydrous soil treatment agent of the present invention that has achieved the above object contains (a) a water-soluble polymer and (b) gypsum having a specific surface area of 0.11 to 1.63 m ² / cm ³ as constituent elements. However, it has a gist. In the hydrous soil treatment agent of the present invention, (a) the water-soluble polymer containing a carboxyl group (including a carboxylate group, the same applies hereinafter) and / or a sulfone group (including a sulfonic acid group, the same applies hereinafter) Further, those having a carboxyl group and having a sulfone group-containing unit in an amount of 0.5 to 50 mol% in 100 mol% of all the constituent units are preferable. Further, (b) gypsum is preferably hemihydrate gypsum and / or anhydrous gypsum.

Hereinafter, in the present specification, unless otherwise specified, the “carboxyl group” in the water-soluble polymer and the monomer for forming the polymer includes, in addition to a free carboxyl group (—COOH group). And a carboxylate group, and unless otherwise specified, the “sulfone group” also includes a sulfonate group in addition to a free sulfone group (—SO ₃ H group).

  The case where the above-mentioned hydrous soil treating agent further comprises (c) a hydraulic material as a component is also a preferred embodiment of the present invention.

  The granulation method of the hydrous soil of the present invention has a gist in that the hydrous soil treatment agent of the present invention is mixed with the hydrous soil to form a granular soil (that is, the granulation method of the hydrous soil of the present invention includes: This is a method for producing granular soil). The granulation method of the present invention includes, for example, a procedure in which (a) a water-soluble polymer and (b) gypsum are mixed almost simultaneously with a hydrated soil, or (a) a step in which the water-soluble polymer is mixed with a hydrated soil. It is preferred to carry out the procedure of mixing (b) gypsum before the hydrous soil is granulated. It is desirable that the hydraulic substance (c), which is one of the constituents of the hydrous soil treatment agent, be added after the hydrous soil is granulated.

  The hydrous soil treatment agent of the present invention has excellent hydrous soil treatment performance due to the action of gypsum having a specific specific surface area used as a constituent element, and the flow value is a very high water content soil having a very large value. Can also be used in small amounts, for example as granular soil which can be used as a substitute for sand.

  As described above, the agent for treating a hydrous soil and the method for granulating the hydrous soil of the present invention can reuse the hydrous soil normally discarded as sludge, so that environmental preservation, resource saving, and extension of the disposal place can be extended. In addition, it is possible to reduce the disposal cost of the hydrated soil.

  As described above, conventionally, granular soil obtained by treating hydrated soil using a treatment agent comprising a water-soluble polymer disclosed in Patent Document 2, for example, can be further treated with a hydraulic substance to increase the strength. It has been known that gypsum can be effectively used as such a hydraulic substance.

  However, the present inventors have found that in the case of gypsum having a specific form, it is not an action of hardening the once formed granular soil and increasing its strength, but mixing it with the water-soluble soil almost simultaneously with the water-soluble polymer. Alternatively, by adding the water-soluble polymer to the hydrous soil and then adding and mixing the granules before the hydrous soil is granulated, a very excellent hydrous soil treatment effect (granulation effect) is exhibited, and the conventional hydrous soil treatment is performed. With the agent, it was found that soil having a high water content and low viscosity, which could not be granulated, could be granulated, and the present invention was completed.

That is, the greatest feature of the water-containing soil treating agent of the present invention resides in that (a) a water-soluble polymer and (b) gypsum having a specific surface area of 0.11 to 1.63 m ² / cm ³ are included in constituent elements. have.

  The mechanism of hydrous soil treatment by the hydrous soil treatment agent of the present invention is considered to be as follows. When the water-soluble polymer is added to and mixed with the water-containing soil, the water-soluble polymer binds to water while dissolving in the water, thereby taking up the water and incorporating the water into the water-soluble polymer. Molecular chains are adsorbed to some soil particles and adhere to each other.However, in the case of soil with a high water content, the water-soluble polymer alone has a weak power to bind the soil particles, so it is stable. In order to form a granular state, it is necessary to increase the amount of addition. However, by coexisting a gypsum of the above-described form in the system where the water-containing soil and the water-soluble polymer are present, crosslinking of the water-soluble polymer occurs via the gypsum, increasing the apparent molecular weight. The cohesive force is improved. Thereby, a stronger bond is formed between the soil particles, and the water in the hydrous soil is included in the gaps between the soil particles, so that a stable granulated product can be obtained. In addition, since the specific type of gypsum also has hydraulic property, the obtained granulated product can be solidified (details will be described later). In this case, the granulated material after solidification has a neutral pH, for example, unlike solidified granules obtained from cement, which is one of hydraulic substances. Hereinafter, the components of the hydrous soil treatment agent of the present invention will be described in detail.

  The water-soluble polymer (a) used in the present invention is not particularly limited as long as it can be dissolved in water at 25 ° C. in an amount of 0.1% by mass or more. Specific examples include polyether polymers such as polyethylene oxide and polypropylene oxide; amide polymers such as polyacrylamide and polymethacrylamide; lactam-containing polymers such as polyvinylpyrrolidone; hydroxyl-containing polymers such as polyvinyl alcohol; , Hydroxyethyl cellulose and other natural nonionic water-soluble polymers; polyacrylic acid, polymethacrylic acid, polymaleic acid and other carboxyl group-containing polymers; polystyrenesulfonic acid and sulfonated polymers of polyisoprene; alginic acid Anionic water-soluble polymers such as soda and carboxymethyl cellulose or metal salts thereof; amine-type polymers such as polyethyleneimine; pyridine-containing polymers such as polyvinylpyridine; Cationic water-soluble polymer or a salt thereof, such as chitosan; Ruaminoechiru (meth) quaternary ammonium salt-containing polymers, such as acrylate and the like.

  (A) In synthesizing a water-soluble polymer, two or more monomers constituting the water-soluble polymer may be used in combination, or other monomers such as (meth) acrylamide, dimethylacrylamide, and (meth) Monomers such as acrylonitrile, styrene, alkyl (meth) acrylate [eg, methyl (meth) acrylate, ethyl (meth) acrylate], hydroxyethyl (meth) acrylate, vinyl acetate, etc., to such an extent that water solubility is not affected Some may be used together.

  Among these, a water-soluble polymer obtained by polymerizing a carboxyl group-containing monomer or a water-soluble polymer obtained by polymerizing (meth) acrylamide is safe and has no sticky feeling, It is preferably used because it is a dry powder under normal humidity.

  Examples of the carboxyl group-containing monomer that can be used for the synthesis of the carboxyl group-containing water-soluble polymer include (meth) acrylic acid, crotonic acid, vinyl acetic acid, maleic acid, itaconic acid, mesaconic acid, fumaric acid, citraconic acid, N- (meth) acryloyl aspartic acid and carboxylic acid salts of these monomers (for example, alkali metal salts and ammonium salts) are mentioned. These polymerizable monomers can be used alone or in combination of two or more. Among the above exemplified monomers, (meth) acrylic acid and salts thereof are preferable, and (meth) acrylic acid is more preferable.

  The above-mentioned carboxyl group-containing water-soluble polymer preferably further contains a sulfone group. The carboxyl group-containing water-soluble polymer as described above has a relatively slow dissolution rate in water, and the hydrous soil treatment agent using such a water-soluble polymer requires a relatively long time for treating the hydrous soil (granulation time). May be longer. However, even with such a carboxyl group-containing water-soluble polymer, the introduction of a sulfone group or a sulfonate group greatly increases the dissolution rate in water, so that a hydrous soil treatment agent using such a water-soluble polymer is used. In this way, it becomes possible to granulate the hydrous soil in a short time.

  Further, the sulfone group-containing monomer that can be used for the synthesis of the water-soluble polymer containing a sulfone group is not particularly limited as long as it is a polymerizable monomer having a sulfone group. For example, 2-acrylamide-2- Methylpropanesulfonic acid, (meth) allylsulfonic acid, allyloxybenzenesulfonic acid, 2-hydroxy-3- (2-propenyloxy) propanesulfonic acid, isopropenylsulfonic acid, styrenesulfonic acid, vinylsulfonic acid, sulfoethyl (meth A) Sulfonates of acrylates and isoprene, and sulfonates of these monomers (such as alkali metal salts and ammonium salts). These monomers may be used alone or in combination of two or more. Among the monomers exemplified above, 2-acrylamido-2-methylpropanesulfonic acid, sulfoethyl (meth) acrylate, and salts thereof are preferable, and 2-acrylamido-2-methylpropanesulfonic acid and sulfoethyl (meth) acrylate are preferable. Particularly preferred. Therefore, as the water-soluble polymer containing a carboxyl group and a sulfone group, a monomer composition containing (meth) acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid and / or sulfoethyl (meth) acrylate is polymerized. The water-soluble polymer obtained by this is most preferred.

  In the formation of the carboxyl group-containing water-soluble polymer and the carboxyl group- and sulfone group-containing water-soluble polymer, other monomers copolymerizable with the above-described carboxyl group-containing monomer and the sulfone group-containing monomer are used. A body may be used. Such other monomers include, for example, monoethylenically unsaturated acids such as allylphosphonic acid, isopropenylphosphonic acid, vinylphosphonic acid, and salts thereof; polyethylene glycol (meth) acrylate, methoxypolyethylene glycol ( Esters of polyalkylene glycol and the above-mentioned carboxyl group-containing monomer, such as (meth) acrylate; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, hydroxyethyl (meth) (Meth) acrylic esters such as acrylate and hydroxypropyl (meth) acrylate; vinyl esters such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate and vinyl cinnamate; methyl vinyl ether, d Alkyl vinyl ethers such as vinyl ether; allyl alcohol, methallyl alcohol, 3-methyl-3-buten-1-ol, 3-methyl-2-buten-1-ol, 2-methyl-3-buten-2-ol, etc. Unsaturated vinyl alcohols; vinyl monomers containing aldehyde groups such as acrolein; vinyl monomers containing nitrile groups such as (meth) acrylonitrile; amide monomers such as (meth) acrylamide and Nt-butylacrylamide; Ethyl methacrylate; styrene; ethylene oxide adduct of allyl alcohol; N-vinyl-2-pyrrolidone; N-vinylacetamide; N-vinylformamide;

  Among other monomers exemplified above, monoethylenically unsaturated acids; esters of polyalkylene glycol and the above-mentioned carboxyl group-containing monomer; (meth) acrylates; vinyl esters; alkyl vinyl ethers; Gases such as ammonia may be generated during treatment of hydrous soil, such as phosphoethyl methacrylate; styrene; ethylene oxide adduct of allyl alcohol; N-vinyl-2-pyrrolidone; N-vinylacetamide; N-vinylformamide. Absent monomers are more preferred. These other monomers may be used alone or in combination of two or more as necessary. Among other monomers exemplified above, methyl (meth) acrylate, hydroxyethyl (meth) acrylate, and N-vinyl-2-pyrrolidone are particularly preferable.

  For example, in the above-mentioned carboxyl group-containing water-soluble polymer, the carboxyl group-containing unit accounts for 50 mol% or more, more preferably 75 mol% or more, and still more preferably 80 mol% or more, based on 100 mol% of all the constituent units of the water-soluble polymer. Desirably. When the amount of the carboxyl group-containing unit is below the above range, it may be necessary to increase the amount of the hydrous soil treating agent used for hydrous soil. On the other hand, in the carboxyl group-containing water-soluble polymer, all of the constituent units (that is, 100 mol%) may be carboxyl group-containing units. In this case, however, it becomes susceptible to the metal ions present in the soil, and When the avoidance of such a phenomenon is required because the fluctuation range of the use amount of the agent may be large, the amount of the carboxy group-containing unit is preferably 99.5 mol% or less, more preferably 99 mol% or less. Is more preferred.

  In the water-soluble polymer containing a carboxyl group and a sulfone group, the content of the sulfone group-containing unit is 0.5 mol% or more, more preferably 1 mol% or more, and 100 mol% of all the constituent units of the water-soluble polymer. %, More preferably 25 mol% or less, further preferably 20 mol% or less. The carboxyl group-containing unit amount may be selected from the above-mentioned preferable range of the carboxyl group-containing water-soluble polymer while satisfying the preferable range of the sulfone group-containing unit amount.

  In the present specification, the carboxyl group-containing water-soluble polymer or the above-mentioned `` constituent unit '' in the carboxyl group- and sulfone group-containing water-soluble polymer means a basic unit constituting these water-soluble polymers. The carboxyl group-containing unit means a carboxyl group-containing unit among these basic units, and the sulfone group-containing unit means a sulfone group-containing unit.

  When the amount of the sulfone group-containing unit is below the above range, the effect of improving the water dissolution rate of the polymer due to the introduction of the sulfone group may not be sufficiently ensured. It may be necessary to increase the usage.

  In the above-mentioned water-soluble polymer containing a carboxyl group and a sulfone group, the preferred molar ratio of the carboxyl group to the sulfone group derived from the above-mentioned preferred range of the amount of the carboxyl group-containing unit and the amount of the sulfone group-containing unit is 199: 1. １1: 1, and the molar ratio is more preferably 99: 1 to 4: 1. The molar ratio between the carboxyl group and the sulfone group in the water-soluble polymer can be determined, for example, by a colloid titration using an aqueous solution adjusted to pH = 2 and an aqueous solution adjusted to pH = 10 according to a conventional method. The measurement can be easily performed.

  Production of the above-mentioned water-soluble polymer containing a carboxyl group and a water-soluble polymer containing a carboxyl group and a sulfone group [hereinafter, these polymers are collectively referred to as "a water-soluble polymer containing a carboxyl group (and a sulfone group)"] The method is not particularly limited, and includes, for example, a polymerization method using a polymerization initiator such as a radical polymerization initiator; a polymerization method of irradiating radiation such as ionizing radiation and electron beam, or an electromagnetic wave such as ultraviolet light; and a polymerization method by heating. And various other known polymerization methods, and two or more of these polymerization methods can be used in combination.

  Further, as the polymerization mode, conventionally known various polymerization modes such as suspension polymerization, solution polymerization, emulsion polymerization, bulk polymerization, and the like can be adopted, and further, these can be any of batch type and continuous type. I do not care.

  The radical polymerization initiator that can be used when the polymerization method using the above-described polymerization initiator is employed is not particularly limited, and examples thereof include ammonium persulfate, potassium persulfate, hydrogen peroxide, benzoyl peroxide, and t-butyl peroxide. Peroxides; sodium bisulfite, sodium metabisulfite, ammonium ferrous sulfate, L-ascorbic acid, triethanolamine and the like; reducing agents suitably used in redox systems; 2,2′-azobis (2, 4-dimethylvaleronitrile), 2,2'-azobis (2-aminopropane) dihydrochloride, 2,2'-azobisisobutylamide dihydrate, 2,2'-azobis [2- (2-imidazoline -2-yl) propane] dihydrochloride, azo initiators such as 4,4'-azobis (4-cyanopentanoic acid); and the like. The amount of the polymerization initiator and the conditions of the polymerization reaction are not particularly limited, and may be appropriately determined according to the type and amount of the monomer used.

  The weight average molecular weight of the above-mentioned water-soluble polymer containing a carboxyl group (and a sulfone group) is not particularly limited, but is, for example, 100,000 or more, more preferably 500,000 or more, further preferably 1,000,000 or more, and 20,000,000 or more. Below, it is recommended that it is more preferably 10 million or less. When the weight average molecular weight exceeds the above range, the dissolution rate in water may decrease, and in the hydrous soil treating agent containing such a water-soluble polymer as a component, the viscosity increases when mixed with hydrous soil. In addition to the effect, it may be difficult to mix both uniformly, and the synthesis of the polymer itself tends to be difficult. On the other hand, when the weight average molecular weight is below the above range, the hydrous soil treatment agent using this water-soluble polymer may deteriorate the hydrous soil treatment performance (granulation performance). According to the study of the present inventors, generally, the weight-average molecular weight of the water-soluble polymer, the higher molecular weight side even within the above range, tend to have excellent hydrous soil treatment performance. It is known.

  Incidentally, from the viewpoint of handleability of the hydrous soil treatment agent, the suitable viscosity of the aqueous solution of the water-soluble polymer [not limited to the water-soluble polymer containing a carboxyl group (and a sulfone group)] is, for example, 0.2% by mass in concentration. In the case of 25 ° C., the pressure is 5 to 10000 mPa · s, more preferably 10 to 2000 mPa · s. Therefore, it is also preferable to adjust the weight average molecular weight of the water-soluble polymer so as to achieve such an aqueous solution viscosity.

  As described above, in the water-soluble polymer containing a carboxyl group (and a sulfone group), the carboxyl group contained therein may be present as a free carboxyl group or a carboxylate group. More preferably, it is contained. Specific examples of the carboxylate group include alkali metal salts such as sodium salt and potassium salt; alkaline earth metal salts such as calcium salt and magnesium salt; ammonium salt; amine salt; It is not limited to.

  The proportion of free carboxyl groups in 100 mol% of carboxyl groups contained in the carboxyl group (and sulfone group) -containing water-soluble polymer is preferably 5 mol% or more, more preferably 20 mol% or more, and more preferably 40 mol%. %, More preferably at least 60 mol%. When the ratio of the free carboxyl group is lower than the lower limit, the hydrous soil treatment agent using such a water-soluble polymer may deteriorate the hydrous soil treatment performance. Depending on the nature of the hydrous soil to be treated (e.g. hydrous soil discharged in the Kanto region), the proportion of free carboxyl groups is most preferably 100 mol%.

  When the water-soluble polymer containing a carboxyl group (and a sulfone group) has a carboxylate group or a sulfonate group, it contains a carboxylate group or a sulfonate group as a monomer for forming these water-soluble polymers. After synthesizing a polymer once using a monomer having a free carboxyl group or a free sulfone group, a part or all of the free carboxyl group or the free sulfone group is synthesized. It may be neutralized to form a salt (carboxylate group, sulfonate group). Examples of alkalis that can be used for neutralization include hydroxides and carbonates of alkali metals such as sodium, potassium and lithium; ammonia; alkylamines such as monomethylamine, diethylamine, trimethylamine, monoethylamine, dimethylamine and triethylamine; Alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, isopropanolamine and secondary butanolamine can be mentioned, and hydroxides and carbonates of sodium are generally used.

  Further, among the (a) water-soluble polymers, the water-soluble polymer containing a sulfone group and the sulfone group in the above-mentioned water-soluble polymer containing a carboxyl group and a sulfone group are polymerizable to form the water-soluble polymer. In addition to the groups previously possessed by the monomer, they may be groups introduced by post-modification of a specific polymer.

  In introducing the sulfone group by post-modification, the base polymer (post-modification polymer) may be, for example, a carboxyl group-containing monomer described above, a sulfone group-containing monomer described above, or another monomer. In addition to the monomers exemplified above, those obtained by polymerizing monomers (for example, those having two or more double bonds in a molecule such as butadiene or isoprene) by the various methods exemplified above can be used. Among such post-modification polymers, poly (meth) acrylic acid is preferred, and polyacrylic acid is more preferred.

  As a post-modification method for introducing a sulfone group into the above-mentioned post-modification polymer, a method of reacting the water-soluble polymer with a sulfone group-introducing compound described later can be employed. For example, a method in which a carboxyl group contained in the post-modification polymer and a hydroxyl group contained in sodium isethionate (sodium hydroxyethanesulfonate), which is a sulfone group-introducing compound, are ester-bonded; To form an amide bond between a carboxyl group to be formed and an amino group contained in sodium taurine salt (sodium aminoethanesulfonate) as a sulfone group-introducing compound; post-modification using fuming sulfuric acid or the like as a sulfone group-introducing compound A sulfonation polymer; a method of adding sodium sulfite, which is a sulfone group-introducing compound, to a double bond contained in the post-modification polymer; and the like. Absent.

  The sulfone group-introducing compound is not particularly limited as long as it can introduce a sulfone group into the post-modification polymer. Specific examples other than the compounds exemplified above include compounds suitable for forming an ester bond such as sodium hydroxymethanesulfonate and sodium hydroxypropanesulfonate; compounds suitable for forming an amide bond such as sodium aminomethanesulfonate and aminopropanesulfonic acid. Compounds; and the like.

  The reaction method and conditions for the post-modification are not particularly limited, and may be appropriately selected depending on the sulfone group-introduced compound to be used and the type of the reaction. For example, a method in which a post-modification polymer and a sulfone group-introduced compound are mixed and heated may be employed. In addition, the amount of the sulfone group-introduced compound to the post-transformation polymer is not particularly limited, and the type of the polymer or the compound, a combination thereof, or the like, so as to satisfy a necessary amount of the sulfone group. It may be determined appropriately. It is also possible to use a water-soluble polymer containing a carboxyl group and a sulfone group as the polymer for post-modification, and carry out the above-mentioned post-modification for the purpose of increasing the amount of sulfone groups in the water-soluble polymer.

  In quantifying the amount of the sulfone group-containing unit in the water-soluble polymer into which the sulfone group was introduced by post-modification, the basic unit in which the sulfone group was introduced by post-modification was also included in the sulfone group-containing unit. I do.

  (A) When a water-soluble polymer is used in the water-containing soil treating agent of the present invention, the polymer may be an aqueous solution, an emulsion, or a powder. Depending on the type and molecular weight of the water-soluble polymer (a), the aqueous solution has a very high viscosity, and the handleability may be reduced, or the miscibility with the hydrated soil may be reduced during the treatment with the hydrated soil. Therefore, in the case of such an aqueous solution of a water-soluble polymer, it may be necessary to use a large amount of water to lower the concentration of the aqueous solution and lower the viscosity. Therefore, in consideration of handleability and miscibility with water-containing soil, (a) the water-soluble polymer is preferably dried and pulverized as necessary to be used as a powder. The method for drying and pulverizing the (a) water-soluble polymer is not particularly limited, and a conventionally known method may be employed.

  (A) When the water-soluble polymer is used as a powder (particle), the average particle diameter is preferably 0.01 to 2 mm, more preferably 0.02 to 1 mm. If the water-soluble polymer (a) has an average particle diameter in such a range, even if the treating agent containing the water-soluble polymer as a component is mixed with the hydrated soil, it is difficult to form a flour, and the handleability is good. It is.

The gypsum (b) used in the present invention has a specific surface area of 0.11 m ² / cm ³ or more and 1.63 m ² / cm ³ or less. In the treating agent of the present invention, as described above, (b) gypsum is used to form a bond between water-soluble polymer molecules. (B) When gypsum has such a specific surface area, The treating agent has a higher performance of treating hydrous soil (granulation performance) than ever before, and also facilitates the treatment of very low viscosity soil with high water content. Although the reason is not clear, the gypsum having a large specific surface area as described above has a large area capable of reacting with the water-soluble polymer molecule, so that the bond (crosslinking) between the water-soluble polymer molecules can be quickly formed. I think that it is because the action is exerted. In addition, since (b) gypsum also has hydraulic property, it is possible to solidify granular soil. (B) a specific surface area of the gypsum is 0.15 m ² / cm ³ or more, more preferably 0.20 m ² / cm ³ or more, 1.50 m ² / cm ³ or less, more preferably 1.00 m ² / cm It is recommended that it be ³ or less.

  When the specific surface area is less than the above range, the average particle size of gypsum (b) tends to increase, so that the effect of (a) binding the water-soluble polymer to improve the cohesive strength is reduced. In addition, in the case of gypsum hemihydrate or anhydrous gypsum, the effect of taking in free water by the hydration reaction is exhibited, but when the specific surface area is below the above range, such an effect is reduced. On the other hand, if the specific surface area exceeds the above range, the amount of calcium ions eluted into the treatment system increases, causing (a) insolubilization of the water-soluble polymer. Or increase the granularity of the hydrous soil.

  The specific surface area of the gypsum (b) specified in the present invention is determined using Nikkiso Co., Ltd. Microtrac FRA particle size distribution analyzer “9200-FRA”, using acetone as a measurement solvent, and setting related to (substance) (substance to be measured). Of these, Transparency (light transmittance) is “Yes”, Spherical Particle (selection of true sphere or not) is “No”, and Particle Refractive Index (absolute refractive index of particles) is the case of anhydrous gypsum and hemihydrate gypsum. Is set to "1.55", and in the case of gypsum, it is set to "1.52". For [Solvent] setting, the Fluid Refractive Index (absolute refractive index of the solvent) is measured as the absolute refractive index of acetone (1.36). Value.

  The average particle size of the gypsum (b) is preferably 800 μm or less. If the gypsum has such an average particle size, even if it is mixed with water-containing soil, it will not easily become a step and can be processed smoothly. The average particle size is more preferably 635 μm or less, and further preferably 600 μm or less. On the other hand, the average particle size of the gypsum (b) is preferably 7 μm or more, more preferably 10 μm or more. The average particle size of the gypsum (b) is a value obtained when the above specific surface area measurement is performed.

  (B) The type of gypsum may be any of hemihydrate gypsum (calculated gypsum), anhydrous gypsum, gypsum dihydrate (gypsum dihydrate), and a mixture thereof. // Anhydrite is preferred. Since these can undergo a hydration reaction, they can take in highly free water to a high degree, so that it is possible to further enhance the treatment performance of the hydrous soil treatment agent. In addition, since the granular soil can be solidified, the strength of the granular soil can be increased.

  Further, in the hydrous soil treatment agent of the present invention, (b) the granular soil after treatment can be solidified by the hydraulic property of gypsum, but if necessary, for example, when the granular soil requires further improvement in strength. (C) A hydraulic substance can also be used. The hydraulic substance is not particularly limited as long as it hardens in water, and examples thereof include cement, quicklime, slaked lime, gypsum (semihydrate gypsum, anhydrous gypsum), and a mixture thereof. Among the hydraulic substances exemplified above, cement is preferred. Further, as for gypsum, any of those having a specific surface area corresponding to the gypsum of the above (b) and those having a specific surface area not applicable to the (b) can be used as the hydraulic substance (c). In the granulation method of the present invention using the hydrous soil treatment agent, in a normal mode, (c) the hydraulic substance is obtained by mixing (a) a water-soluble polymer or (b) gypsum with hydrous soil. Since it is added after forming the granular soil (details will be described later), even when (b) a material having a specific surface area corresponding to gypsum is used as (c) a hydraulic material, it is treated as a separate component. obtain.

  As the above cement, various known cements can be employed. Examples include, but are not limited to, Portland cement such as ordinary Portland cement, early-strength Portland cement, ultra-high-strength Portland cement, blast furnace cement, alumina cement, calcium cement, fly ash cement, and the like. Among them, blast furnace cement can be preferably employed because hexametallic chromium, which is a heavy metal, is not substantially eluted.

  In addition, in the hydrous soil treatment agent of the present invention, a water-absorbent resin, a water-absorbent fiber substance (cellulose, pulp, recovered waste paper, etc.), talc, bentonite, acid clay, alumina, kaolin, silica, zeolite, perlite, silica sand, diatomaceous earth, Fly ash or the like can be used as a component as necessary.

  Preferred forms of the hydrous soil treatment agent of the present invention include: [1] a powdery material in which (a) a powdery water-soluble polymer and (b) a gypsum powder are mixed in advance; A powdery (a) water-soluble polymer and a powdery (b) gypsum separately packaged; [3] (a) an aqueous solution or emulsion of a water-soluble polymer; (B) a form in which gypsum and gypsum are separately packaged can be adopted. In the case where (c) a hydraulic substance is also a constituent element, the hydraulic substance may be used in any of the forms [1] to [3], with (a) a water-soluble polymer or (b) gypsum. Is preferably employed in a separately packaged form. The reason will be described later.

  The method for granulating hydrated soil with the hydrated soil treating agent of each of the above forms is as follows. In the case of the above form [1], (a) the water-soluble polymer and (b) gypsum are simultaneously mixed and treated (granulated) with the hydrous soil. In the case of the above [2] or [3], it is possible to mix (a) a water-soluble polymer and (b) gypsum, which are separately packaged, almost simultaneously with hydrous soil and granulate them. It is also possible to employ a method in which (a) the water-soluble polymer is mixed first, and then (b) gypsum is mixed and granulated before the hydrous soil is granulated. The time until (b) gypsum is added after mixing the (a) water-soluble polymer is not particularly limited, but after the water-containing soil and (a) the water-soluble polymer are sufficiently mixed, (b) the gypsum is removed. Depending on the size of the treatment scale, it is preferable to add gypsum, for example, after (a) about 20 to 180 seconds after mixing of the water-soluble polymer, it is recommended. You. After the treatment of the hydrous soil is started, that is, in the case of the above-mentioned [1], (a) the water-soluble polymer and (b) gypsum are mixed into the hydrous soil, and then the above [2] or In the case of the embodiment [3], the time from (a) mixing the water-soluble polymer into the hydrated soil to the completion of granulation of the hydrated soil (total treatment time) is desirably 420 seconds or less.

  The (c) hydraulic substance is preferably added after mixing (a) the water-soluble polymer and (b) gypsum to granulate the hydrous soil. If (c) the hydraulic substance is added before the granulation of the hydrated soil, the hydrated soil may not be able to be granulated.

  The method of mixing the water-containing soil with (a) the water-soluble polymer or (b) gypsum is not particularly limited, but it is preferable to use a mixer capable of stirring and mixing these without kneading them. For example, a device provided with a stirring blade having a rod-shaped or hook-shaped shape is preferable so that the mixture can be stirred while applying a shearing force. In other words, the stirring blade has a shape that is as wide as possible in the direction perpendicular to the moving direction of the mixture that is moved by stirring and mixing, so that the coarsening of the particle diameter due to kneading can be suppressed and the stirring blade and the inner wall of the device can be prevented. This is desirable because the mixture can be prevented from adhering to the substrate.

  Examples of such a device include a horizontal axis type mixer and a vertical axis type mixer. As the horizontal axis type mixer, a single axis and a multi axis type paddle type mixer are preferable. As the vertical axis type mixer, for example, a pan mixer type mixer is preferable, and a planetary type mixer is more preferable, and among the planetary type mixers, a soil mixer, a mortar mixer, and an Eirich mixer are particularly preferable.

  A shorter time to granulation is preferred in terms of working efficiency, and is usually within several minutes. By the agitation, the hydrous soil becomes smooth granular soil. The particle size of the granular soil is preferably about 0.1 to 100 mm, and more preferably 0.1 to 10 mm.

  The method of mixing (c) a hydraulic substance with (a) a granular soil obtained by mixing (a) a water-soluble polymer or (b) gypsum is not particularly limited. It is desirable to use a device that can be stirred and mixed without kneading. In addition, the shearing is not applied as much as the mixing of the water-containing soil and (a) the water-soluble polymer or (b) gypsum. For example, the surface of the granular soil is covered with (c) a hydraulic substance. Preferably, it is attached. On the other hand, part of the hydraulic substance may be taken into the granular soil.

  The amount of the treating agent used in the treatment of the hydrated soil varies depending on the mode of the hydrated soil (water content ratio, viscosity, type of soil component, etc.). It is recommended that the combined amount be 0.01 part by mass or more and 5 parts by mass or less, more preferably 1 part by mass or less. Further, (b) the amount of gypsum used is 1 part by mass or more, more preferably 5 parts by mass or more, and 100 parts by mass or less, more preferably 60 parts by mass or less, based on 100 parts by mass of hydrous soil. Is desirable. Furthermore, in the case of using (c) a hydraulic substance, the amount of use is 1 part by mass or more, and 35 parts by mass or less, more preferably 20 parts by mass or less, based on 100 parts by mass of hydrous soil. Is recommended. Therefore, the usage ratio of each component in the hydrous soil treatment agent of the present invention may be determined within the above-mentioned preferred usage of each component with respect to 100 parts by mass of hydrous soil.

  In a water-containing soil, even if the water content ratio is the same, the viscosity differs depending on the composition of the soil and the like, and the ease of treatment also differs. Taking into account the influence of such a difference in component composition, as an index for evaluating the properties related to the viscosity of hydrous soil, for example, there is a flow value obtained by the measurement method described below, the hydrous soil treatment agent of the present invention and In the granulation method, not only the soil having a relatively low water content of about 55 mm or more and less than 70 mm but also the soil having a high water content and a low viscosity of about 70 mm or more and a flow value of about 1000 mm or less, which is a target of the conventional treatment agent, is used. However, it is possible to obtain a granular soil having a particle size of a conventional level with a small amount of use as described above, and it has extremely excellent hydrous soil treatment performance. Incidentally, Patent Literature 2 discloses an example in which a soil with a high water content of, for example, 120% is treated. However, the treated soil used here is the soil of Kanto loam, and the flow value is 65 mm. Less than.

  The above flow value is obtained as follows. After placing a hollow cylinder having an inner diameter of 55 mm and a height of 55 mm on a table, filling the cylinder with hydrous soil, and lifting the cylinder vertically, measuring the diameter of the hydrous soil spread on the table in two directions. Then, the average value is used as a flow value.

  The granular soil obtained by the treating agent and the granulating method of the present invention can be transported by truck, and can be reused for various uses such as a backfill material as a substitute for sand.

  Hereinafter, the present invention will be described in detail based on examples. However, the following embodiments do not limit the present invention, and all modifications and alterations without departing from the spirit of the preceding and following embodiments are included in the technical scope of the present invention. In this example, “parts” are based on mass unless otherwise specified.

<Water-soluble polymer>
The water-soluble polymer used in the following Examples and Comparative Examples is a copolymer of acrylic acid: 90 mol% and sodium 2-acrylamido-2-methylpropanesulfonate: 10 mol%, and is synthesized by the following production method. It is.

  In a 1 L stainless steel separable flask (I) equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube, 340 g of cyclohexane and 4.59 g of sorbitan monostearate were placed, and stirred at 50 ml / min. Nitrogen was introduced at the rate described above, and the temperature was raised to 70 ° C.

  Acrylic acid: 113.05 g, 2-acrylamido-2-methylpropanesulfonic acid: 36.11 g, 48 mass in a 500 ml separable flask (II) equipped with a stirrer, thermometer, reflux condenser and nitrogen inlet tube. % Sodium hydroxide aqueous solution: 14.54 g and ion-exchanged water: 133.71 g were added and stirred to dissolve. After nitrogen was introduced into the solution of the separable flask (II) for 25 minutes while stirring was continued, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride was added in an amount of 0.1%. A separable flask containing 42.62 g of an aqueous solution containing 02% by mass, 0.02% by mass of 4,4′-azobis (4-cyanopentanoic acid), and 0.02% by mass of sodium hypophosphite monohydrate By adding nitrogen to the solution of (II) and further introducing nitrogen for 5 minutes, the dissolved oxygen in the solution was reduced to 1 mg / L or less. Thereafter, the monomer prepared in the separable flask (II) was fed into the separable flask (I) over 2 hours to carry out polymerization, followed by aging for 30 minutes. After subsequent dehydration, the content was cooled to 30 ° C., and the content was subjected to solid-liquid separation, followed by drying to obtain a water-soluble polymer (white fine particles).

  For a 0.2% by mass aqueous solution of this water-soluble polymer, the rotor: No. The viscosity at 25 ° C. measured under the conditions of 2, 30 rpm was 83 mPa · s.

<Evaluation soil>
Evaluation soil A
The evaluation soil A is a hydrous soil obtained by sufficiently mixing Toyoura standard sand: 5 parts, silt: 75 parts, clay: 270 parts, and tap water: 350 parts. For this evaluation soil, the flow value determined by the above-described measurement method was 250 mm.

Evaluation soil B
Evaluation soil B is a hydrous soil obtained by sufficiently mixing Toyoura standard sand: 5 parts, silt: 75 parts, clay: 270 parts, and tap water: 280 parts. For this evaluation soil, the flow value obtained by the above-described measurement method was 185 mm.

<Gypsum>
Gypsum used in Examples and Comparative Examples described below was obtained by pulverizing a plaster purchased from Wako Pure Chemical Industries, Ltd. in a mortar to adjust the specific surface area. Table 1 shows the specific surface area and average particle size of these gypsums. The specific surface area and the average particle diameter in Table 1 were measured using Nikkiso Co., Ltd. Microtrac FRA particle size distribution analyzer “9200-FRA”, using acetone as a measurement solvent under the following conditions. [Materials] Transparency (light transmission): “Yes”, Spherical Particle (selection of true sphere or not): “No”, Particle Refractive Index (absolute refractive index of particle): “1.55 (anhydrogypsum / half) Water gypsum) "or" 1.52 (gypsum gypsum) ", [solvent]: acetone, Fluid Refractive Index (absolute refractive index of solvent): 1.36.

Example 1
Evaluation soil A: 100 parts were charged into a mixer provided with a beater-type stirring blade, and while stirring at 160 rpm, 0.18 parts of the water-soluble polymer and gypsum No. 1 shown in Table 1 were added. 6 (anhydrite): A treating agent in which 10 parts were previously mixed was added, and the mixture was stirred for 360 seconds to treat the evaluation soil. The condition of the evaluation soil after the treatment was evaluated according to the criteria shown in Table 2. Table 3 shows the results.

Example 2
Evaluation soil A: 100 parts was charged into a mixer provided with a beater-type stirring blade, and while stirring at 160 rpm, 0.16 parts of a water-soluble polymer was added, followed by stirring for 170 seconds. Then, the gypsum No. shown in Table 1 was used. 6 (anhydrite): 10 parts were added, and the mixture was further stirred for 40 seconds to treat the evaluation soil. The condition of the evaluation soil after the treatment was evaluated according to the criteria shown in Table 2. Table 3 shows the results.

Example 3
Evaluation soil A: 100 parts were charged into a mixer provided with a beater-type stirring blade, and while stirring at 160 rpm, 0.18 parts of the water-soluble polymer and gypsum No. 1 shown in Table 1 were added. 6 (anhydrite): A treating agent prepared by mixing 5 parts in advance was added and stirred for 310 seconds. Thereafter, 5 parts of Portland cement (hydraulic substance; manufactured by Taiheiyo Cement Co., Ltd.) was added, and the mixture was further stirred for 20 seconds to treat the evaluation soil. The condition of the evaluation soil after the treatment was evaluated according to the criteria shown in Table 2. Table 3 shows the results.

Example 4
Evaluation soil A: 100 parts was charged into a mixer provided with a beater-type stirring blade, and while stirring at 160 rpm, 0.21 part of the water-soluble polymer was added to gypsum No. 1 shown in Table 1. 8 (Gypsum dihydrate): A treatment agent in which 10 parts were previously mixed was added, and the mixture was stirred for 200 seconds. Thereafter, 5 parts of Portland cement (hydraulic substance; manufactured by Taiheiyo Cement Co., Ltd.) was added, and the mixture was further stirred for 30 seconds to treat the evaluation soil. The condition of the evaluation soil after the treatment was evaluated according to the criteria shown in Table 2. Table 3 shows the results.

Example 5
Evaluation soil A: 100 parts were charged into a mixer provided with a beater-type stirring blade, and while stirring at 160 rpm, 0.18 parts of the water-soluble polymer and gypsum No. 1 shown in Table 1 were added. 3 (anhydrite): A treating agent in which 10 parts were previously mixed was added, and the mixture was stirred for 210 seconds to treat the evaluation soil. The condition of the evaluation soil after the treatment was evaluated according to the criteria shown in Table 2. Table 3 shows the results.

Example 6
Evaluation soil A: 100 parts were charged into a mixer provided with a beater-type stirring blade, and while stirring at 160 rpm, 0.18 parts of the water-soluble polymer and gypsum No. 1 shown in Table 1 were added. 5 (anhydrite): A treating agent in which 10 parts were previously mixed was added, and the mixture was stirred for 340 seconds to treat the evaluation soil. The condition of the evaluation soil after the treatment was evaluated according to the criteria shown in Table 2. Table 4 shows the results.

Example 7
Evaluation soil A: 100 parts were charged into a mixer provided with a beater-type stirring blade, and while stirring at 160 rpm, 0.18 parts of the water-soluble polymer and gypsum No. 1 shown in Table 1 were added. 4 (anhydrite): A treating agent in which 10 parts were previously mixed was added, and the mixture was stirred for 165 seconds to treat the evaluation soil. The condition of the evaluation soil after the treatment was evaluated according to the criteria shown in Table 2. Table 4 shows the results.

Example 8
Evaluation soil A: 100 parts was charged into a mixer provided with a beater-type stirring blade, and while stirring at 160 rpm, 0.25 part of the water-soluble polymer and gypsum No. 1 shown in Table 1 were added. 9 (hemihydrate gypsum): A treatment agent in which 10 parts were previously mixed was added, and the mixture was stirred for 210 seconds to treat the evaluation soil. The condition of the evaluation soil after the treatment was evaluated according to the criteria shown in Table 2. Table 4 shows the results.

Example 9
Evaluation soil A: 100 parts was charged into a mixer provided with a beater-type stirring blade, and while stirring at 160 rpm, 0.25 part of the water-soluble polymer and gypsum No. 1 shown in Table 1 were added. 9 (hemihydrate gypsum): A treatment agent in which 20 parts were previously mixed was added, and the mixture was stirred for 90 seconds to treat the evaluation soil. The condition of the evaluation soil after the treatment was evaluated according to the criteria shown in Table 2. Table 4 shows the results.

Example 10
Evaluation soil A: 100 parts was charged into a mixer provided with a beater-type stirring blade, and while stirring at 160 rpm, 0.25 part of the water-soluble polymer and gypsum No. 1 shown in Table 1 were added. 9 (hemihydrate gypsum): A treatment agent in which 5 parts were previously mixed was added, and the mixture was stirred for 160 seconds. Thereafter, 5 parts of blast furnace cement (hydraulic substance; manufactured by Taiheiyo Cement Co., Ltd.) was added, and the mixture was further stirred for 15 seconds to treat the evaluation soil. The condition of the evaluation soil after the treatment was evaluated according to the criteria shown in Table 2. Table 4 shows the results.

Comparative Example 1
Evaluation soil B: 100 parts were charged into a mixer provided with a beater-type stirring blade, 0.6 parts of a water-soluble polymer was added while stirring at 160 rpm, and the evaluation soil was treated by stirring for 300 seconds. Was. That is, this comparative example is an example in which gypsum is not used. The condition of the evaluation soil after the treatment was evaluated according to the criteria shown in Table 2. Table 5 shows the results.

Comparative Example 2
Evaluation soil A: 100 parts were charged into a mixer provided with a beater-type stirring blade, and while stirring at 160 rpm, 0.18 parts of the water-soluble polymer and gypsum No. 1 shown in Table 1 were added. 2 (anhydrite): A treatment agent in which 10 parts were previously mixed was added, and the mixture was stirred for 420 seconds to treat the evaluation soil. The condition of the evaluation soil after the treatment was evaluated according to the criteria shown in Table 2. Table 5 shows the results.

Comparative Example 3
Evaluation soil A: 100 parts were charged into a mixer provided with a beater-type stirring blade, and while stirring at 160 rpm, 0.18 parts of the water-soluble polymer and gypsum No. 1 shown in Table 1 were added. 7 (anhydrite): A treating agent in which 10 parts were previously mixed was added, and the mixture was stirred for 300 seconds to treat the evaluation soil. The condition of the evaluation soil after the treatment was evaluated according to the criteria shown in Table 2. Table 5 shows the results.

Comparative Example 4
Evaluation soil A: 100 parts were charged into a mixer provided with a beater-type stirring blade, and while stirring at 160 rpm, 0.18 parts of the water-soluble polymer and gypsum No. 1 shown in Table 1 were added. 7 (anhydrite): A treating agent preliminarily mixed with 5 parts was added, and the mixture was stirred for 300 seconds to treat the evaluated soil. The condition of the evaluation soil after the treatment was evaluated according to the criteria shown in Table 2. Table 5 shows the results.

Comparative Example 5
Evaluation soil A: 100 parts were charged into a mixer provided with a beater-type stirring blade, and while stirring at 160 rpm, 0.18 parts of the water-soluble polymer and gypsum No. 1 shown in Table 1 were added. 1 (anhydrite): A treatment agent in which 10 parts were previously mixed was added, and the mixture was stirred for 330 seconds to treat the evaluation soil. The condition of the evaluation soil after the treatment was evaluated according to the criteria shown in Table 2. Table 5 shows the results.

  In Table 2, those having an evaluation value of 4 or more after processing are acceptable and those having an evaluation value of 3 or less are unacceptable. In the case of evaluation values 4 and 5 (granulation state evaluation: ○), granulation was achieved to such an extent that it could be easily transported by truck or the like. Is also possible. Further, those having evaluation values of 6 and 7 (granulation state evaluation: ◎) can be suitably used as a backfill material.

  In Tables 3-5, among the methods of adding gypsum, "mixing" was previously mixed with the water-soluble polymer and added to the evaluation soil, and "post-addition" was a mixture of the water-soluble polymer and the evaluation soil. The later additions mean respectively. Further, the numerical value of “granulated state” means the evaluation value in Table 2.

  As shown in Tables 3 and 4, in Examples 1 to 10, as the gypsum used for the hydrous soil treatment agent, a gypsum having a specific surface area within the range of the present invention was used. The granular soil after the treatment was suitable for a backfill material.

  On the other hand, Comparative Examples 2 and 5 shown in Table 5 are those in which the specific surface area of the gypsum used for the hydrous soil treatment agent is lower than the range of the present invention, and Comparative Examples 3 and 4 are those in which the gypsum used in the hydrous soil treatment agent is used. The specific surface area was beyond the range of the present invention, and it was not possible to obtain a granular soil having a fine particle size, and the treated hydrous soil was unsuitable as a backfill material. Also, in Comparative Example 1 in which gypsum was not used, the same results as Comparative Examples 2 to 5 were obtained.

Claims (9)

A hydrous soil treatment agent comprising (a) a water-soluble polymer and (b) gypsum having a specific surface area of 0.11 to 1.63 m ² / cm ³ as constituent elements.   The water-soluble soil treating agent according to claim 1, wherein the water-soluble polymer contains a carboxyl group (including a carboxylate group, the same applies hereinafter) and / or a sulfone group (including a sulfonic acid group, the same applies hereinafter). .   3. The agent for treating hydrous soil according to claim 2, wherein the water-soluble polymer has a carboxyl group, and the sulfone group-containing unit accounts for 0.5 to 50 mol% in 100 mol% of all constituent units. 4.   The hydrous soil treating agent according to any one of claims 1 to 3, wherein the gypsum is hemihydrate gypsum and / or anhydrous gypsum.   The agent for treating hydrous soil according to any one of claims 1 to 4, further comprising (c) a hydraulic substance as a constituent element.   A method for granulating hydrous soil, comprising mixing the hydrous soil treatment agent according to any one of claims 1 to 5 into hydrous soil.   The granulation method according to claim 6, wherein (a) the water-soluble polymer and (b) gypsum are simultaneously mixed into the hydrous soil.   The granulation method according to claim 6, wherein (a) the water-soluble polymer is mixed with the hydrated soil, and (b) gypsum is mixed before the hydrated soil is granulated.   The granulation method according to claim 7 or 8, wherein (c) a hydraulic substance is added after the hydrous soil is granulated.