JP2002038152A - Water-reducing agent for soil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-reducing agent which is used for soil and can reduce water, when the water is added to occurring soil or hydraulic substance- added occurring soil to impart flowability to the soil. SOLUTION: This water-reducing agent for soil, characterized by containing a polymer which has structural units represented by general formula (1) [R1, R2, R3 and R4 are each independently H, an alkyl, an alkenyl, or an aryl; (n) is an integer of 1 to 500] and carboxy group-based substituents.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water reducing agent for soil used in, for example, improvement of soft ground and fluidization of generated soil by excavation or dredging.

[0002]

2. Description of the Related Art Conventionally, in the case of improving soft ground composed of hydrated soil, hydrated soil (generated soil) obtained by excavating and dredging the ground includes cement, lime, etc. (hydraulic material).
Is uniformly added and backfilled to harden the soft ground. In addition, a method has been adopted in which a hydraulic substance is uniformly added to generated soil discharged from a construction site and reused as landfill soil.

[0003] Further, as a method of use other than backfilling and landfilling on site, there is a method of once carrying the generated soil into a plant, adding a solidifying agent, processing it into sand or gravel, and reusing it as an improved material. Has been adopted.

[0004] By the way, in order to improve the soft ground by backfilling, and when reclaiming, in order to secure the strength of the ground after backfilling (or after reclamation), a hydraulic substance is uniformly added to the generated soil. In addition, it is required that the generated soil after the addition of the hydraulic substance is uniformly poured into the expected backfill site or the expected reclamation site so that no cavity is formed. Although depending on properties such as the initial moisture content of the generated soil, generally, a great effort is required to uniformly mix the hydraulic substance and the generated soil. In addition, since the fluidity of the generated soil to which the hydraulic substance is added is considerably low and the workability is not good, there is a problem that it is necessary to perform measures such as leveling and compaction to achieve uniformity.

[0005]

Therefore, in order to avoid such a problem, a method of securing fluidity by adding water to the above-mentioned generated soil or the generated soil to which a hydraulic substance is added has been adopted. However, due to the nature that the water treatment is performed on site,
Work space is limited and it is necessary to avoid increasing the volume of generated soil by adding water. In addition, there is no guarantee that a large amount of water or muddy water is always available near the site. In other words, it is required to reduce the amount of water or mud provided for the water treatment as much as possible.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to reduce the amount of water when imparting fluidity to the above-mentioned generated soil or generated soil to which a hydraulic substance has been added. An object of the present invention is to provide a soil water reducing agent that can be reduced.

[0007]

Means for Solving the Problems The inventors of the present application have studied diligently to provide a soil water reducing agent capable of reducing the amount of water added to generated soil when imparting fluidity to the generated soil. . As a result, they found that a compound (polymer compound) having a specific structure having a carboxyl group or an alkali metal salt thereof as a substituent can be suitably used as the soil water reducing agent, and completed the present invention. Was.

That is, in order to solve the above problems, the soil water reducing agent according to the present invention comprises a polymer having a structural unit represented by the above general formula (1) and a carboxyl group-based substituent. It is characterized by consisting of

[0009] In order to solve the above-mentioned problems, the soil water reducing agent of the present invention comprises a copolymer of a polyalkylene glycol monomer and an unsaturated carboxylic acid monomer. It is characterized by.

[0010] In order to solve the above-mentioned problems, the soil water reducing agent according to the present invention also comprises a copolymer of a monomer represented by the above general formula (2) and an unsaturated carboxylic acid monomer. It is characterized by comprising coalescence.

In order to solve the above-mentioned problems, the soil water reducing agent according to the present invention is characterized by comprising a polymer obtained by graft-polymerizing a monoethylenically unsaturated carboxylic acid to a polyether compound.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The "soil" in which the soil water reducing agent according to the present invention is used includes not only generated soil obtained by excavation and dredging (for example, soft clay and construction residual soil), but also soil. The concept includes a soil composition in which a solidifying agent (a hydraulic substance) such as cement or lime is added to the generated soil.
The above-mentioned generated soil refers to all the soil generated by construction on the ground, and more preferably one having a relatively small particle size constituent unit such as gravel, sand, silt, and clay as a main component.
In particular, secondary particles (natural structural units, that is, pedds) can be easily formed by adding water or stirring after adding water.
Further, those which can be loosened to the size of the primary particles are preferable. In addition, the generated soil includes generated soil (secondary generated soil) such as muddy residual soil generated “secondarily” by adopting a muddy water shield method or the like. In addition, the "secondary generated soil" referred to here means not only the ground excavated or the like, but also the generated soil generated by excavation or the like with further secondary processing such as water addition.

[0013] These "soils" are basically based on the premise that water is added in order to impart fluidity, but the soil water reducing agent according to the present invention provides the soil with fluidity. It can reduce the amount of added water (amount of water added) necessary for application, and in some cases, can be reduced to zero. Less than,
The soil water reducing agent according to the present invention will be described in detail.

The water reducing agent for soil according to the present invention is represented by the following general formula (3): -COOM ¹ or -COOM ² OOC- (3) wherein M ¹ is a hydrogen atom, an alkali metal Atom, an ammonium group, or an organic amine group, M ² represents an alkaline earth metal atom), and includes a polymer having a specific structure having a substituent (generically referred to as a carboxyl group-based substituent). Become. The polymer is preferably hydrophilic,
In this case, the polymer adsorbs small particles such as secondary particles and primary particles that form soil, and due to its own hydrophilicity, the small particles are added to water (water added to impart fluidity). It improves dispersibility. The mechanism of action is not necessarily clear, but it is presumed that the hydrophilic polymer adsorbs small particles constituting soil by its carboxyl group-based substituent.

When the polymer adsorbs small particles mainly by the carboxyl group-substituent, the polymer may be adsorbed between the carboxyl group-substituent and the anion exchange group of the soil (small particles). It is presumed that the chemical adsorption has occurred. Among clay minerals and humus, which are the main ion exchangers constituting soil, representatives having anion exchange groups include allophane, imogolite, 1: 1 type mineral, and 2: 1 type to 2: Examples include 1: 1 type intermediate species minerals, gibbsite, iron oxide minerals, and the like, and it is generally known that their anion exchange capacity increases with a decrease in pH. Therefore, in some cases, the combined use of the soil water reducing agent and the acidic substance according to the present invention is expected to further improve the dispersibility of soil in added water.

One of the soil water reducing agents according to the present invention is 1
In the molecule, the following general formula (1)

[0017]

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(Wherein R ₁ , R ₂ , R ₃ , and R ₄ independently represent a hydrogen atom, an alkyl group, an alkenyl group, or an aryl group, and n represents an integer of 1 or more and 500 or less) And a polymer having at least one structural unit represented by the formula and at least one carboxyl group-based substituent (sometimes referred to as polymer A).

As the above polymer, specifically, for example,
1) a polymer having polyacrylic acid, polymethacrylic acid, or maleic acid polymer as a main chain and at least one polyethylene glycol chain as a side chain; 2) a polyethylene glycol chain as a main chain and at least one side chain. A graft polymerization type polymer such as a polymer having polyacrylic acid, polymethacrylic acid, or a maleic acid polymer can be used, but is not particularly limited thereto. Such a polymer can be produced according to a known polymerization method.

In these polymers, the polyethylene glycol chain corresponds to the structural unit represented by the general formula (1), and the carboxyl group of the polyacrylic acid, polymethacrylic acid, or maleic acid polymer is It corresponds to a carboxyl group-based substituent. In the polyacrylic acid, polymethacrylic acid, or maleic acid polymer, at least a part of the carboxyl group is neutralized to form an alkali metal salt, an alkaline earth metal salt, an ammonium salt, or an amine salt. It may be a neutralized product or a completely neutralized product.

The structural unit represented by the general formula (1) is
It is a site mainly related to the dispersibility of the polymer in water. In the general formula (1), n may be an integer of 1 to 500,
An integer of 5 or more and 100 or less is more preferable, and an integer of 5 or more and 50 or less is further preferable. Further, in the general formula (1), when n is 2 or more, n R ₁ , R ₂ , R ₃ , and R ₄ contained in the structural unit may be different from each other.

On the other hand, the carboxyl group-based substituent is mainly concerned with the adsorptivity to soil, and it is sufficient that at least one unit is contained in one molecule of the polymer. When two or more carboxyl group-based substituents are contained in one molecule of the polymer, these may be different from each other.

In one molecule of the polymer, the above-mentioned general formula (1)
The relationship between the sum of n in the above and the number of carboxyl group-containing substituents is not particularly limited.

The above-mentioned polymer may contain other structural units in addition to the structural unit represented by the general formula (1) and the carboxyl group-based substituent, as long as it does not impair the adsorptivity or hydrophilicity to the soil. For example, it may have a sulfonic acid group, a hydroxyl group-based substituent, or the like. Note that the hydroxyl group-based substituent, the following general formula (4) -OM ^{1, or, -OM 2 O- ····· (4)} ( wherein, M ¹ is a hydrogen atom, an alkali metal atom, an ammonium group , Or an organic amine group, and M ² represents an alkaline earth metal atom).

Further, another soil water reducing agent according to the present invention is a copolymer of a polyalkylene glycol-based monomer and an unsaturated carboxylic acid-based monomer (sometimes referred to as polymer B). It comprises. In this copolymer, the structure derived from the polyalkylene glycol-based monomer is mainly related to the dispersibility in water, and the structure derived from the unsaturated carboxylic acid-based monomer is mainly related to the adsorptivity to soil. It is thought to be involved.

The above-mentioned polyalkylene glycol monomer refers to a monofunctional or higher functional polyalkylene glycol compound to which an unsaturated carboxylic acid monomer can be added. Specifically, for example, an esterified product of a polyalkylene glycol having one end-blocked alkyl group such as alkoxy polyethylene glycol or alkoxy polyethylene polypropylene glycol and acrylic acid or methacrylic acid;
Adducts obtained by adding at least one of ethylene oxide and propylene oxide to acrylic acid, methacrylic acid, allyl alcohol, vinyl alcohol, or the like; and the like. One of these polyalkylene glycol monomers may be used alone, or two or more of them may be used in combination as needed.

The above-mentioned unsaturated carboxylic acid monomer refers to a carboxylic acid compound having an unsaturated bond and usable as a monomer. Specifically, for example, unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; unsaturated dicarboxylic acids such as maleic acid, itaconic acid and citraconic acid; Alkali metal salts, alkaline earth metal salts, ammonium salts, or amine salts; One of these unsaturated carboxylic acid monomers may be used alone, or two or more of them may be used in combination as needed.

The above-mentioned copolymer may be used in addition to the polyalkylene glycol-based monomer and the unsaturated carboxylic acid-based monomer, and other monomer components, as long as the adsorbability to the soil and the hydrophilicity are not impaired. For example, a monomer having a sulfonic acid group,
It may be obtained by polymerizing a monomer composition having a monomer having a hydroxyl-based substituent. Further, the polymerization reaction can be carried out by a general method, and an appropriate polymerization initiator may be used as needed.

Still another soil water reducing agent according to the present invention is represented by the following general formula (2):

[0030]

Embedded image

[0031] (wherein, R ₅ represents an alkenyl group, R ₆
Represents a divalent hydrocarbon group) and an unsaturated carboxylic acid-based monomer (sometimes referred to as polymer C). In this copolymer, the structure derived from the monomer represented by the general formula (2) is mainly involved in dispersibility in water, and the structure derived from the unsaturated carboxylic acid monomer is transferred to the soil. It is thought to be mainly related to the adsorptive properties of the polymer.

Specific examples of the monomer represented by the general formula (2) include, for example, sodium isethionate or sodium p-hydroxybenzenesulfonic acid (phenylsulfonic acid), and acrylic acid or methacrylic acid. Esterified products are listed, and among these, an esterified product of sodium isethionate and acrylic acid is particularly preferable. One of these compounds may be used alone, or two or more of them may be used in combination as needed.

The unsaturated carboxylic acid monomer refers to the same compound as described above. One of these unsaturated carboxylic acid monomers may be used alone, or two or more of them may be used in combination as needed.

The above copolymer may be added to the monomer represented by the general formula (2) or the unsaturated carboxylic acid monomer, as long as the adsorbability to the soil and the hydrophilicity are not impaired. ,
It may be obtained by polymerizing a monomer composition having another monomer component, for example, a monomer having a sulfonic acid group, a monomer having a hydroxyl group-based substituent, or the like. Further, the polymerization reaction can be carried out by a general method, and an appropriate polymerization initiator may be used as needed.

Still another soil water reducing agent according to the present invention comprises a polymer obtained by graft-polymerizing a monoethylenically unsaturated carboxylic acid to a polyether compound (sometimes referred to as polymer D). . In this polymer, it is considered that the structure derived from the polyether compound is mainly concerned with the dispersibility in water, and the structure derived from the monoethylenically unsaturated carboxylic acid is mainly concerned with the adsorptivity to soil.

The above-mentioned polyether compound generally refers to a chain molecule having an ether bond in the main chain, and in particular, the following general formula (5): X—O (CH ₂ CH ₂ O) _m H. (5) (wherein, X is a hydrogen atom, an alkyl group, or an aryl group, and the average number of moles added m represents an integer of 2 or more and 200 or less). Particularly preferred is a skeleton (main chain) in which one end (X in the general formula (5)) of the main chain is an alkyl group such as a methyl group or an aryl group such as a phenyl group or a benzyl group. One of these polyether compounds may be used alone, or two or more of them may be used in combination as needed.

The monoethylenically unsaturated carboxylic acid generally refers to a carboxylic acid having one ethylene group and a carboxyl group bonded to a carbon atom forming the ethylene group. For example, it refers to acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid and the like. One of these monoethylenically unsaturated carboxylic acids may be used alone, or two or more of them may be used in combination as needed.

The above-mentioned polymer may be used in addition to the above-mentioned monoethylenically unsaturated carboxylic acid and other monomer components such as monoethylenically unsaturated sulfonic acid, as long as the polymer does not impair the adsorptivity and hydrophilicity to soil. It may be obtained by graft polymerization of an acid or the like. Further, the polymerization reaction can be carried out according to a general graft polymerization method, and an appropriate polymerization initiator may be used if necessary.

The weight average molecular weight of each of the above polymers A to D is not particularly limited, but is preferably in the range of 1,000 to 100,000, more preferably 5 to 100,000, from the viewpoint of soil dispersibility. It is particularly preferred that it is in the range of 000 to 50,000. In the present invention, “weight average molecular weight” refers to gel permeation (GP
It is a value in terms of polyethylene glycol obtained by the method C).

The soil water reducing agent according to the present invention may contain at least one kind of the above-mentioned polymers A to D, and may contain two or more kinds as needed. Hereinafter, the specific usage of the soil water reducing agent according to the present invention will be described, but the usage is not particularly limited to the following specific examples.

In the case where the "soil" of the present invention is transported to, for example, a plant or a cultivation material close to the site, or when it is reused for backfilling or landfill, the workability is improved. Is required to have a desired fluidity. That is, if the desired fluidity is imparted to the soil, 1) pipe transportation becomes easy, 2) uniform mixing of the composition by stirring becomes easy,
3) When backfilling or reclaiming land, it is easy to work the soil uniformly and without voids. In general, the fluidity to be imparted to the soil is preferably such that the flow value measured by the method described in the following example is in the range of 70 or more, and more preferably in the range of 90 or more. It is said.

The soil water reducing agent according to the present invention is used for the above-mentioned "soil", and can reduce the amount of water added to impart fluidity to the soil, and in some cases, can reduce it to zero. It is. That is, the use of the above-mentioned soil water reducing agent makes it possible to add a small amount of water, or to impart desired fluidity to the soil without adding moisture. Can be minimized. In addition, the amount of water to be secured for the fluidity imparting process can be significantly reduced (or can be reduced to zero). As more specific advantages, 1) a large space (cured dough) even when the soil is once cured at the site
Is unnecessary, 2) the fluidity-imparting treatment can be performed even at the site where it is difficult to secure water, and 3) the working time can be shortened.

Examples of the form of the soil provided with fluidity include, for example, a mixture A composed of 1) generated soil + soil water reducing agent + added water, and 2) generated soil + soil water reducing agent + added. Water + solidifying agent such as cement (hydraulic substance),
And a mortar-like mixture B (generally treated fluidized soil). Usually, a mortar-like mixture B is obtained and reused on site (such as backfill for ground improvement). If necessary, a hardening accelerator such as calcium chloride, triethanolamine, or calcium thiocyanate may be added to the mortar-like mixture B. When the mixture A is prepared, the mixture A may be added and stirred while transporting the mixture A or after transporting the mixture A to a predetermined treatment plant.

The "moisture" used for preparing the above-mentioned mixtures A and B may be water alone, or may be a water mixture such as adjusted muddy water. Then, as shown in the following examples, particularly when the soil water reducing agent according to the present invention is used in the preparation of the mixture B, it is necessary to impart desired fluidity as compared with the case where it is not used. The amount of the "moisture" can be significantly reduced.

The order in which the generated soil, the water reducing agent for soil, water, and the solidifying agent such as cement (when preparing the above mixture B) is added, and the method of uniformly mixing these are not particularly limited. . As an example, a water-reducing agent dispersion (or a water-reducing agent aqueous solution) is prepared by uniformly dispersing or dissolving a water-reducing agent for soil in the above-mentioned water, and the generated soil or generated soil to which a solidifying agent is added (soil according to the present invention) And a water reducing agent dispersion, and uniformly stirring and mixing with a stirring means such as a mortar mixer.

In addition, the above-mentioned water reducing agent for soil, moisture, and solidifying agent for a predetermined amount of generated soil (in the case of the above-mentioned mixture B)
May be determined depending on the quality of the generated soil (initial water content, composition, etc.) and the desired degree of fluidity,
There is no particular limitation. Generally, generated soil 12
The amount of the water reducing agent for soil is 0.1 g in terms of the amount of the polymer.
More preferably, it is added within the range of 6 to 36 g,
More preferably, it is added in the range of 1.2 to 9.6 g. When ordinary Portland cement is used as a solidifying agent, 12 to 12 g of generated soil is used.
More preferably, it is added within a range of 360 g.
More preferably, it is added in the range of up to 240 g.

As described above, in order to impart fluidity to soil, even if the soil water reducing agent of the present invention is used, water addition is basically required. Mud-like residual soil generated by the above (secondary generated soil)
In the case where the solidified product such as cement is added to the soil, it may be unnecessary to add the water by using the soil water reducing agent of the present invention. As an example, if a solidified material is added to the muddy residual soil, its fluidity is reduced,
In some cases, the addition of water is required to ensure the desired fluidity. In such a case, the soil water reducing agent according to the present invention is first added to the muddy residual soil to sufficiently disperse the soil components, and then the solidified product is added. Liquidity can be secured.

Also, although the initial moisture content of the soil is extremely high,
Even if the desired fluidity is not reached as it is, the soil water reducing agent of the present invention is added to the soil and stirred to sufficiently disperse the soil components, so that the desired water content can be obtained without further adding moisture. It may be possible to ensure liquidity.

[0049]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited thereto. In Examples and Comparative Examples, “%” refers to “% by weight” unless otherwise specified.
(% By mass) ".

First, the generated soil and soil used in the following Examples and Comparative Examples and a method for evaluating the fluidity of the soil will be described.

As the generated soil, one having a water content of 48% generated by general civil engineering work in the Kanto region was used. The particle size composition of the generated soil was 20% for sand, 50% for silt, and 30% for clay. Then, 100 g of ordinary Portland cement (solidifying agent, hydraulic substance) is added to 1200 g of the generated soil, and the mixture is kneaded with a mortar mixer at low speed for 30 seconds to obtain a test soil (soil in the present invention). Was prepared.

The soil for the test is given a fluidity by adding a water and a water reducing agent for the soil according to the description of each Example and Comparative Example, and the fluidity is given by the flow value (expansion). Was evaluated. More specifically, an object to be measured for flow value (soil with fluidity: fluidized soil) is placed in a hollow cylindrical container having a diameter of 55 mm and a height of 50 mm placed on a horizontal table surface. Then, the container is vertically lifted to a height exceeding 50 mm, the maximum diameter of the measurement object spread on the table surface is measured in two directions, and the average value is defined as a flow value (unit: mm). did. The higher the flow value, the higher the fluidity of the measurement object,
A flow value of 55 mm indicates that the object to be measured has almost no fluidity.

Example 1 First, a thermometer, a stirrer,
In a glass reaction vessel equipped with a dropping funnel, a nitrogen inlet tube and a reflux condenser, 546 g of ion-exchanged water, 83 g of maleic acid (unsaturated carboxylic acid monomer), and 1 mol of 3
800 g of a polyalkylene glycol monoalkenyl ether monomer (polyalkylene glycol-based monomer) obtained by adding ethylene oxide to 50-mol-methyl-3-buten-1-ol at a rate of 65 mol. After the temperature was raised to ° C., 2.4 g of 30% aqueous hydrogen peroxide (polymerization initiator) was added via a dropping funnel. Subsequently, L-ascorbic acid (reducing agent) was added to 39.1 g of ion-exchanged water.
An aqueous solution obtained by dissolving 0.9 g was dropped into the reaction vessel from the dropping funnel over 1 hour, and then aged for 1 hour while maintaining the temperature at 65 ° C. to complete the polymerization reaction.

Next, the reaction solution was adjusted to pH 8 using a 30% aqueous sodium hydroxide solution to obtain an aqueous solution of the polymer (1). The weight average molecular weight of the obtained polymer (1) was 30,500. The polymer (1) corresponds to the polymers A and B described in the embodiment, and was added to the test soil as the soil water reducing agent according to the present invention.

More specifically, 100 g of ordinary Portland cement was added to 1200 g of the generated soil, and 20% of the above polymer (1) was added to the test soil obtained by kneading at a low speed with a mortar mixer for 30 seconds. 18 g of the aqueous solution was charged, and the mixture was kneaded with the mortar mixer at a high speed for 3 minutes to obtain a fluidized soil. And the flow value was measured using the fluidized soil. Weight average molecular weight (molecular weight) of polymer (1), amount of water added to generated soil (added water amount: unit weight (mass)%), added amount of polymer (1) solid content to generated soil (polymer amount : Unit weight%),
The measurement results of the flow values are shown in Table 1 below.

Example 2 A fluidized treated soil was obtained according to the method described in Example 1 except that 36 g of a 20% aqueous solution of the polymer (1) was added to the test soil. The flow value of the treated soil was measured. The measurement results of the weight average molecular weight of the polymer (1), the amount of water added to the generated soil, the added amount of the polymer (1) solids to the generated soil, and the flow value are shown in Table 1 below.

Example 3 100.6 g of ion-exchanged water was charged into the same glass reaction vessel as in Example 1, and the inside of the reaction vessel was sufficiently purged with nitrogen while stirring with a stirrer. Heated to ° C. Then, methoxypolyethylene glycol monomethacrylate (esterified product of alkoxypolyethylene glycol and methacrylic acid:
Average number of moles of ethylene oxide added per molecule 2
5) An aqueous solution of a mixture consisting of 121.2 g, 13.8 g of methacrylic acid (unsaturated carboxylic acid monomer), 0.7 g of mercaptopropionic acid (chain transfer agent), and 33.5 g of ion-exchanged water, and 5% 24 g of an ammonium sulfate aqueous solution (polymerization initiator) was added dropwise from a different dropping funnel over 4 hours. Subsequently, 5 g of a 5% aqueous solution of ammonium persulfate was added dropwise from the dropping funnel over 1 hour, and the reaction was continued for 1 hour while maintaining the temperature at 80 ° C. to complete the polymerization reaction. Then, the reaction solution was adjusted to pH 7 using a 30% aqueous sodium hydroxide solution, and polymer (2)
Was obtained. The weight average molecular weight of the obtained polymer (2) was 23,000. The polymer (2) corresponds to the polymer B described in the embodiment, and is added to the above-mentioned test soil as a soil water reducing agent according to the present invention, and the flow value is measured. Was.

More specifically, fluidized soil was obtained according to the method described in Example 1 except that 18 g of a 20% aqueous solution of the polymer (2) was used instead of the aqueous solution of the polymer (1). The flow value of the fluidized soil was measured. The measurement results of the weight average molecular weight of the polymer (2), the amount of water added to the generated soil, the amount of the polymer (2) solids added to the generated soil, and the flow value are summarized in Table 1 below.

Example 4 A fluidized soil was obtained according to the method described in Example 3 except that 36 g of a 20% aqueous solution of the polymer (2) was charged into the test soil. The flow value of the treated soil was measured. The measurement results of the weight average molecular weight of the polymer (2), the amount of water added to the generated soil, the amount of the polymer (2) added to the generated soil, and the flow value are shown in Table 1 below.

Example 5 100 g of phenoxy polyethylene glycol (polyether compound) having a weight-average molecular weight of 1,500 was placed in the same glass reaction vessel as in Example 1.
And maleic acid (monoethylenically unsaturated carboxylic acid) 5
g) and heated under a stream of nitrogen to dissolve them, and the temperature was raised to 150 ° C. while stirring with a stirrer. Next, while keeping the temperature within the range of 150 ° C to 151 ° C,
Acrylic acid (monoethylenically unsaturated carboxylic acid) 30 g
And di-t-butyl peroxide (polymerization initiator) 4.5
g were continuously dropped from different dropping funnels over 1 hour. Subsequently, after stirring with a stirrer for 40 minutes, the reaction system was cooled, and 135 g of pure water was added thereto to obtain an aqueous solution of the polymer (3). The weight average molecular weight of the obtained polymer (3) was 15,400. The polymer (3) corresponds to the polymer D described in the embodiment, and is added to the above-mentioned test soil as a soil water reducing agent according to the present invention, and the flow value is measured. Was.

More specifically, a fluidized soil was obtained according to the method described in Example 1 except that 18 g of a 20% aqueous solution of the polymer (3) was used instead of the aqueous solution of the polymer (1). The flow value of the fluidized soil was measured. The measurement results of the weight average molecular weight of the polymer (3), the amount of water added to the generated soil, the amount of the polymer (3) solid content added to the generated soil, and the flow value are shown in Table 1 below.

Example 6 100 g of ion-exchanged water was charged into the same glass reaction vessel as in Example 1, and the inside of the reaction vessel was sufficiently purged with nitrogen while stirring with a stirrer. Heated. Next, a mixture aqueous solution consisting of 20 g of acrylic acid (unsaturated carboxylic acid monomer), 10 g of an esterified product of sodium isethionate and methacrylic acid, 0.7 g of mercaptopropionic acid (chain transfer agent), and 20 g of ion-exchanged water, And 20 g of a 5% aqueous solution of ammonium persulfate (polymerization initiator) were added dropwise from different dropping funnels over 4 hours. Subsequently, 5 g of a 5% aqueous solution of ammonium persulfate was added dropwise from the dropping funnel over 1 hour, and the reaction was continued for 1 hour while maintaining the temperature at 80 ° C. to complete the polymerization reaction. Then, the reaction solution was
The pH was adjusted to 7 using a 0% aqueous sodium hydroxide solution to obtain an aqueous solution of the polymer (4). The weight average molecular weight of the obtained polymer (4) was 32,000. The polymer (4) corresponds to the polymer C described in the embodiment, and is used as a soil water reducing agent according to the present invention.
It was added to the above test soil and the flow value was measured.

More specifically, a fluidized soil was obtained according to the method described in Example 1 except that 18 g of a 20% aqueous solution of the polymer (4) was used instead of the aqueous solution of the polymer (1). The flow value of the fluidized soil was measured. The measurement results of the weight average molecular weight of the polymer (4), the amount of water added to the generated soil, the amount of the polymer (4) solid content added to the generated soil, and the flow value are shown in Table 1 below.

COMPARATIVE EXAMPLE 1 Water was added to the test soil
8.8 g was charged, and the mixture was kneaded with the mortar mixer at a high speed for 3 minutes to obtain a fluidized soil, and the flow value of the fluidized soil was measured. The amount of water added to the generated soil,
The measurement results of the flow values are collectively shown in Table 1 below.

[0065]

[Table 1]

As is clear from Table 1, the fluidized soil of Comparative Example 1 has almost no fluidity. On the other hand, Comparative Example 1
In Examples 2 and 4 to which the same amount of water was added, the flow value was significantly improved as compared with the result of Comparative Example 1.
That is, if the water reducing agent for soil according to the present invention is used, it is possible to give the soil a larger flow value (fluidity) by adding the same amount of water. In other words, it is possible to greatly reduce the amount of added water necessary for providing the soil with a desired flow value, as compared with the case where the soil water reducing agent is not used.

[0067]

According to the soil water reducing agent of the present invention,
It is possible to reduce the amount of water added to impart predetermined fluidity to soil, or to reduce it to zero. That is,
The use of the above-mentioned soil water reducing agent makes it possible to add a small amount of water, or to impart desired fluidity to the soil without adding moisture. It can be suppressed to the limit. In addition, there is an effect that the amount of water to be secured for the fluidity imparting process can be significantly reduced (or can be set to 0).

As a more specific advantage, 1) a large space (cultivation material) even when the soil is once cured at the site.
Is unnecessary, 2) the fluidity-imparting treatment can be performed even at the site where it is difficult to secure water, and 3) the working time can be shortened.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09K 17/22 C09K 17/22 P 4J100 E02D 3/00 101 E02D 3/00 101 // C08F 290/06 C08F 290/06 (C04B 28/02 (C04B 28/02 24:26 24:26 EF)) H 103: 30 103: 30 C09K 103: 00 C09K 103: 00 F term (reference) 2D043 CA01 EA01 EA02 EA04 EA06 EA10 4G012 PB16 PB31 PB32.

Claims (4)

[Claims] (1) The following general formula (1): (Wherein, R ₁ , R ₂ , R ₃ , and R ₄ independently represent a hydrogen atom, an alkyl group, an alkenyl group, or an aryl group, and n represents an integer of 1 to 500). Water reducing agent comprising a polymer having a structural unit and a carboxyl group-based substituent. 2. A soil water reducing agent comprising a copolymer of a polyalkylene glycol monomer and an unsaturated carboxylic acid monomer. 3. The following general formula (2): (Wherein, R ₅ represents an alkenyl group, and R ₆ represents a hydrocarbon divalent group), and a copolymer of an unsaturated carboxylic acid-based monomer. A water reducing agent for soil, characterized in that: 4. A soil water reducing agent comprising a polymer obtained by graft-polymerizing a monoethylenically unsaturated carboxylic acid to a polyether compound.