Soil modifier and method for treating mud

Abstract

To provide a soil modifier that can reduce the fluidity of mud in a short time and impart appropriate firmness, and a method for treating mud using the same. [Solution] A soil modifier containing a polymer modifier that satisfies the following conditions. (conditions) (Viscosity in emulsion state) - (Viscosity in 0.5% by mass aqueous solution) > 0

Description

[Technical Field]

[0001] The present invention relates to a soil modifier and a method for treating soil. [Background technology]

[0002] During construction work requiring excavation, such as shield tunneling and foundation work for large buildings, mud containing a large amount of water is sometimes discharged. Because mud is highly fluid and has low strength, it needs to be transported from the excavation site in order to be disposed of or used for other purposes, and it is not suitable for transport in its muddy state.

[0003] To transport mud, it is necessary to moderately reduce its fluidity and moderately increase its strength, that is, to impart plastic fluidity to the mud. To date, it has been proposed to impart plastic fluidity to mud by adding a solidifying agent such as gypsum and a polymer modifier (see, for example, Patent Document 1). However, this combined use of a solidifying agent and a polymer modifier takes time to impart plastic fluidity to the mud, making it difficult to use in urban areas or other places where there is no place to allow the mud to cure. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-120261 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The present invention aims to provide a soil modifier that can reduce the fluidity of soil in a short time and impart appropriate firmness, and a method for treating soil using the same. [Means for solving the problem]

[0006] In order to achieve the above object, the inventors of the present invention considered how the soil modifier disperses in the entire soil. When the soil modifier is added to the soil, the components of the soil modifier will disperse not only in the water in the soil but also in the water called interstitial water existing between the soil particles. In order for the soil modifier to quickly disperse in the soil, it was considered necessary to have physical properties that can quickly disperse in both water and interstitial water. Therefore, the inventors of the present invention thought that if the components of the soil modifier have the property that the viscosity decreases when dissolved in water, the viscosity will decrease when the components are added to the soil and will quickly disperse in water and interstitial water, and thus arrived at the present invention.

[0007] The soil modifier of the present invention is characterized by containing a polymer modifier that satisfies the following conditions. (Condition) (Viscosity in the state of emulsion) - (Viscosity in 0.5 mass% aqueous solution) > 0

[0008] Also, in an aspect of the present invention, It is preferable that the viscosity of the polymer modifier in the state of emulsion is 500 cps or less.

[0009] Also, in an aspect of the present invention, It is preferable that the viscosity of the polymer modifier in a 0.5 mass% aqueous solution is 500 cps or less.

[0010] Another aspect of the method for treating soil of the present invention is characterized by mixing a soil modifier containing a polymer modifier that satisfies the following conditions into the soil. (Condition) (Viscosity in the state of emulsion) - (Viscosity in 0.5 mass% aqueous solution) > 0 [Advantages of the Invention]

[0011] According to the present invention, it is possible to provide a soil modifier that can reduce the fluidity of soil in a short time and impart appropriate firmness, and a method for treating soil using the same. [Embodiments for Carrying Out the Invention]

[0012] (Soil modifier) The soil modifier according to the embodiment contains a polymer modifier and, if necessary, other components.

[0013] <Polymer modifier> The polymer modifier satisfies the following conditions. (Condition) (Viscosity in the emulsion state) - (Viscosity in a 0.5 mass% aqueous solution)> 0

[0014] The difference between the viscosity in the emulsion state and the viscosity in a 0.5 mass% aqueous solution (Viscosity in the emulsion state) - (Viscosity in a 0.5 mass% aqueous solution). Hereinafter, it may be referred to as formula (1)) is greater than 0, that is, if the viscosity in the emulsion state is greater than the viscosity in a 0.5 mass% aqueous solution, it can be dispersed in the soil in a short time, reduce the fluidity of the soil in a short time, and impart an appropriate hardness. Here, the appropriate hardness means that the cone index is 240 kN / m 2 or more. Generally, the soil before being made into soil, also called generated soil, has a cone index of 200 kN / m 2 or more, while the soil has a cone index of less than 200 kN / m 2 2 2 or less. Modifying the soil means that the cone index of the modified soil (also called improved soil) after mixing the soil and the soil modifier is 200 kN / m However, in the case of modification on a large scale at the site rather than on a small scale indoors, errors are likely to occur in the degree of soil modification depending on the location of the soil to be modified. Therefore, in the technology used at the site, construction safety factors are often considered when determining the threshold for judging whether it is soil or not. Therefore, the soil with an appropriate hardness that is not soil is 240 kN / m obtained by multiplying the above-mentioned cone index threshold of 200 kN / m 2 by the on-site construction safety factor of 1.2, 2 or more.

[0015] In one embodiment of the present invention, the value of formula 1 is greater than 0 cps, preferably 5 cps or more, more preferably 10 cps or more, and even more preferably 15 cps or more. Furthermore, the value of Equation 1 is preferably 350 cps or less, more preferably 300 cps or less, and even more preferably 250 cps or less.

[0016] The emulsion state in the above (conditions) refers to a state in which the polymer modifier and oil, etc., are mixed. If the polymer modifier is a commercially available product, it refers to the state in which it is sold. Examples of emulsions include water-in-oil emulsions and oil-in-water emulsions, but water-in-oil emulsions are preferred.

[0017] The viscosity in the emulsion state is preferably 500 cps or less, and more preferably 450 cps or less. Furthermore, in one embodiment, the viscosity in the emulsion state is preferably 250 cps or higher. A viscosity of 250 cps or higher in the emulsion state prevents sedimentation of the components and provides excellent stability. In addition, in a specific embodiment of the present invention, the viscosity in the emulsion state is preferably 300 cps or higher, more preferably 350 cps or higher, and even more preferably 400 cps or higher.

[0018] The viscosity of an emulsion (also called "bulk viscosity") can be measured using the same methods as for measuring emulsions. For example, it can be measured using a Brookfield viscometer equipped with a spindle No. 3 at a rotation speed of 30 rpm. The viscosity in the emulsion state is the viscosity at 25°C.

[0019] The viscosity of a 0.5% by mass aqueous solution in the above (conditions) refers to the viscosity when the emulsion of the polymer modifier is dispersed in an aqueous solution. The viscosity of a 0.5% by mass aqueous solution can be measured at 25°C using a Brookfield viscometer with spindle No. 2 rotating at 30 rpm.

[0020] The viscosity of a 0.5% by mass aqueous solution of the polymer modifier can be appropriately selected according to the purpose, regardless of the composition of the soil being treated (sand, clay, water content, etc.), but is preferably 500 cps or less, more preferably 150 cps to 350 cps, and even more preferably 200 cps to 300 cps.

[0021] The polymer modifier of the present invention may mean a flocculant polymer, also called a polymer flocculant. The term "polymer" as used herein means a homopolymer prepared from one monomer, or a copolymer prepared from at least two different monomers.

[0022] The polymer modifier of the present invention is a water-soluble polymer that dissolves, for example, in an amount of 1 g or more, preferably 5 g or more, and more preferably 10 g or more, per liter of water at atmospheric pressure at 25°C.

[0023] The polymer modifier of the present invention may be natural, synthetic, or semi-synthetic. Preferably, the flocculant polymer is synthetic. A semi-synthetic polymer may mean a natural polymer that has undergone a chemical reaction in which different synthetic substituents are grafted onto it.

[0024] The polymer modifier of the present invention may be cationic, anionic, neutral, or amphoteric flocculant polymer. The polymer modifier of the present invention is preferably anionic or amphoteric.

[0025] The polymer modifier of the present invention can have structures such as linear, branched, star-shaped, comb-shaped, or block-shaped, but a linear structure is preferred.

[0026] Examples of monomers that constitute polymer modifiers include anionic hydrophilic monomers, cationic hydrophilic monomers, nonionic hydrophilic monomers, and hydrophobic monomers. These may be used individually or in combination of two or more.

[0027] The term "hydrophilic monomer" in this specification has its ordinary meaning understood in the relevant technical field. For example, it means a monomer with an octanol / water partition coefficient K ow less than or equal to 1. The K ow partition coefficient is determined at 25 °C in an octanol / water mixture having a volume ratio of 1 / 1 and a pH between 6 and 8.

[0028] The term "hydrophobic monomer" in this specification has its ordinary meaning understood in the relevant technical field. For example, it means a monomer with an octanol / water partition coefficient K ow greater than 1. The K ow partition coefficient is determined at 25 °C in an octanol / water mixture having a volume ratio of 1 / 1 and a pH between 6 and 8.

[0029] The octanol / water partition coefficient K ow represents the ratio of the monomer concentration (g / L) between the octanol phase and the aqueous phase. K ow is defined as follows.

[0030]

Equation

[0031] There are no particular restrictions on the anionic hydrophilic monomers, and they can be appropriately selected according to the purpose. For example, monomers having a vinyl functional group can be mentioned. Vinyl functional groups include, for example, acrylic, maleic, fumaric, malonic, itaconic, and allylic acid functional groups. These monomers may contain carboxylate, phosphonate, phosphate, sulfonate, or other negatively charged groups. Specific examples of anionic hydrophilic monomers include acrylic acid, methacrylic acid, dimethylacrylic acid, itaconic acid, C1 - C 22Examples include monomers having vinyl functional groups such as itaconic acid hemiester, itaconamide, acryloyl chloride, crotonic acid, maleic acid, fumaric acid, acrylamide undecanoic acid, and 3-acrylamide 3-methylbutanoic acid; and strong acid monomers having sulfonic acid or phosphonic acid functional groups such as vinyl sulfonic acid, vinyl phosphonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-methylidenepropane-1,3-disulfonic acid, 2-sulfoethyl methacrylate, sulfopropyl methacrylate, sulfopropyl acrylate, allylphosphonic acid, ethylene glycol methacrylate phosphate, styrene sulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid (ATBS), 2-acrylamide-2-methylpropanedisulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, diethylallylphosphonate, and carboxyethyl acrylate. Anionic hydrophilic monomers are water-soluble salts that are alkali metal salts, alkaline earth metal salts, or ammonium salts of all these monomers, or mixtures thereof. Among these, acrylic acid and its salts are preferred.

[0032] There are no particular restrictions on the salts of anionic hydrophilic monomers, and they can be appropriately selected depending on the purpose, but alkali metal salts (Li, Na, K), alkaline earth metal salts (Ca, Mg), and ammonium salts (e.g., ammonium ions or tertiary ammonium) are preferred, and sodium salts are more preferred.

[0033] The content of anionic hydrophilic monomers in polymer modifiers is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5 mol% to 50 mol%, and more preferably 20 mol% to 40 mol%, based on the total number of moles of monomers in the polymer.

[0034] Examples of cationic hydrophilic monomers include vinyl monomers, particularly acrylamide, acrylic, allyl, or maleic acid monomers having a quaternary ammonium functional group. Specific examples of cationic hydrophilic monomers include diallyldialkylammonium salts such as diallyldimethylammonium chloride (DADMAC); acidified or quaternized salts of dialkylaminoalkyl(meth)acrylamide; acidified or quaternized salts of dialkyl-aminoalkyl(meth)acrylamide such as methacrylamide-propyltrimethylammonium chloride (MAPTAC) and acrylamide-propyltrimethylammonium chloride (APTAC); and quaternized or dialkylaminoethyl acrylate chloride (DMAEA). Examples include acidified or quaternized salts of methyl-aminoalkyl acrylates; acidified or quaternized salts of dialkylaminoalkyl methacrylates such as dimethylaminoethyl methacrylate chloride (DMAEMA); vinylamines obtained by hydrolysis (basic or acidic) of an amide group-N(R2)-CO-R1 (where R1 and R2 are independently hydrogen atoms or alkyl chains having 1 to 6 carbon atoms); vinylamines obtained by Hoffmann decomposition; and mixtures thereof. These may be used individually or in combination of two or more. Among these cationic hydrophilic monomers, a structure in which the alkyl group is C1 to C7 is preferred, and a structure in which it is C1 to C3 is more preferred. The structure of the cationic hydrophilic monomer may be linear, cyclic, saturated, or unsaturated. The polymer modifier is preferably a polymer containing at least one cationic hydrophilic monomer, and more preferably a polymer containing quaternized dimethylaminoethyl acrylate (DMAEA) as a monomer.

[0035] The content of cationic hydrophilic monomers in polymer modifiers is not particularly limited and can be appropriately selected depending on the purpose. For example, based on the total number of moles of monomers in the polymer, 10 mol% to 90 mol% is preferred, and 30 mol% to 80 mol% is more preferred.

[0036] Examples of nonionic hydrophilic monomers include water-soluble vinyl monomers. Examples of water-soluble vinyl monomers include acrylamide, methacrylamide, N-alkylacrylamide, N-alkylmethacrylamide, N,N-dialkylacrylamide (e.g., N,N-dimethylacrylamide or N,N-diethylacrylamide), N,N-dialkylmethacrylamide, alkoxylated acrylic acid ester, alkoxylated methacrylate ester, N-vinylpyrrolidone, N-methylol(meth)acrylamide, N-vinylcaprolactam, N-vinylformamide (NVF), N-vinylacetamide, N-vinyl Examples include imidazole, N-vinyl succinimide, acryloylmorpholine (ACMO), glycidyl methacrylate, glyceryl methacrylate, diacetone acrylamide, methacrylic anhydride, acrylonitrile, maleic anhydride, itaconic anhydride, hydroxyalkyl (meth)acrylate, thioalkyl (meth)acrylate, isoprenol and its alkoxylated derivatives, hydroxyethyl (meth)acrylate and its alkoxylated derivatives, hydroxypropyl acrylate and its alkoxylated derivatives, vinyl acetate, and the like. These may be used individually or in combination of two or more. Among these nonionic hydrophilic monomers, the alkyl group is preferably C1-C5, and more preferably C1-C3. Furthermore, the presence of a linear alkyl group is preferable. The polymer modifier is preferably a polymer containing at least one nonionic hydrophilic monomer, and more preferably a polymer containing acrylamide as a monomer.

[0037] The content of nonionic hydrophilic monomers in polymer modifiers is not particularly limited and can be appropriately selected depending on the purpose, but based on the total number of moles of monomers in the polymer, 5 mol% to 50 mol% is preferred, and 20 mol% to 40 mol% is more preferred.

[0038] Polymer modifiers may contain hydrophobic monomers. When using hydrophobic monomers, use an amount that maintains the water solubility of the polymer modifier. Typically, this is less than 5 mol% based on the total number of moles of monomers in the polymer.

[0039] The polymer modifier may contain any additional components such as crosslinking agents, chain transfer agents, radical polymerization initiators, and radical polymerization reaction regulators.

[0040] Examples of crosslinking agents include methylenebisacrylamide (MBA), ethylene glycol diacrylate, tetraallylammonium chloride polyethylene glycol dimethacrylate, diacrylamide, cyanomethyl acrylate, vinyloxyethyl acrylate, vinyl oxymethacrylate, triallylamine, formaldehyde, glyoxal, glycidyl ether, such as ethylene glycol diglycidyl ether, and epoxy, triallylamine, tetraallylammonium chloride (TAAC), and mixtures thereof.

[0041] The crosslinking agent content is preferably 0.1 ppm to 1000 ppm, and more preferably 1 ppm to 100 ppm, relative to the total mass of the polymer modifier.

[0042] Examples of chain transfer agents include 2-mercaptoethanol, 2-propanol, sodium bisulfite, sodium methallyl sulfonate, sodium hypophosphate, and sodium formate.

[0043] The content of the chain transfer agent is preferably 1 ppm to 1000 ppm, and more preferably 1 ppm to 100 ppm, relative to the total mass of the polymer modifier. However, it is preferable that the polymer modifier does not contain a chain transfer agent.

[0044] The mass-average molecular weight of the polymer modifier is not particularly limited and can be appropriately selected depending on the purpose. For example, 10,000 to 30,000,000 is preferred, 50,000 to 25,000,000 is more preferred, and 100,000 to 20,000,000 is even more preferred. The mass-average molecular weight can be measured as polystyrene equivalent by gel permeation chromatography (GPC) at room temperature (25°C).

[0045] The polymer modifier of the present invention is in emulsion form. An emulsion form refers to an emulsion composition containing water, an oily agent, and a surfactant in addition to the polymer modifier.

[0046] The water content is preferably 5% to 50% by mass, and more preferably 10% to 40% by mass, relative to the total mass of the emulsion composition.

[0047] There are no particular restrictions on the type of oil used, and it can be selected appropriately depending on the purpose, but it is usually selected from hydrocarbon oils and mineral oils. Specifically, examples include hydrocarbon oils such as n-hexane, cyclohexane, n-heptane, n-octane, and isooctane, mineral oils such as kerosene, diesel fuel, medium oil, and paraffins, and mixtures thereof.

[0048] The oil content is preferably 5% to 50% by mass, and more preferably 10% to 40% by mass, relative to the total mass of the emulsion composition.

[0049] In one embodiment, in the emulsion composition, the mass ratio of water to oil (water:oil) is preferably 20:80 to 80:20, more preferably 30:70 to 70:30, and even more preferably 40:60 to 60:40, from the viewpoint of emulsion stability.

[0050] Examples of surfactants include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants, but nonionic surfactants are preferred. Examples of nonionic surfactants include polyoxyethylene alkyl ether surfactants, polyoxyethylene alcohol ether surfactants, and polyoxyethylene alkyl ester surfactants.

[0051] The surfactant content in the emulsion composition containing the polymer modifier is preferably 1% to 30% by mass, and more preferably 2% to 20% by mass, relative to the total mass of the emulsion composition.

[0052] The content of the polymer modifier is preferably 10% to 60% by mass, more preferably 20% to 50% by mass, and even more preferably 30% to 45% by mass, based on the total mass of the emulsion composition.

[0053] The amount of polymer modifier added varies depending on the composition of the mud and the structure of the polymer, but from the viewpoint of ensuring homogeneous mixing with the mud and suppressing the increase in viscosity due to excess polymer, 0.5 kg / m³ is recommended. 3 ~20kg / m 3 Preferably, 1 kg / m 3 ~10kg / m 3 More preferably, 2 kg / m 3 ~8kg / m 3 That is even more preferable.

[0054] <Other ingredients> Other ingredients are not particularly limited as long as they are those contained in ordinary soil modifiers, and can be appropriately selected according to the purpose. Examples include mud-adding agents, foaming agents, solidifying agents, fungicides, and preservatives. These may be used individually or in combination of two or more.

[0055] Examples of clay-adding agents include inorganic materials such as clay and bentonite, and organic materials such as gum, starch, cellulose-based materials, acrylic-based materials, and polysaccharides.

[0056] Examples of foaming agents include surfactants.

[0057] Solidifying agents are used to increase strength. Examples of solidifying agents include cement-based solidifying agents, lime-based solidifying agents (quicklime), gypsum-based solidifying agents, and neutral solidifying agents using magnesium or magnesium oxide.

[0058] There are no particular restrictions on the content of other ingredients, and they can be selected as appropriate depending on the purpose.

[0059] (Method for disposing of mud) The method for treating mud according to this embodiment includes a step of mixing a polymer modifier with mud, and further includes other steps as necessary.

[0060] The process of mixing the polymer modifier into the soil involves mixing the polymer modifier into the soil. There are no particular restrictions on the mixing method, and it can be appropriately selected depending on the purpose. Examples include manual stirring, stirring with a mixer, and stirring with a screw conveyor. There are no particular restrictions on the stirring speed; it can be selected as appropriate depending on the purpose.

[0061] Other processes are not particularly restricted and can be selected as appropriate depending on the purpose, for example, a solidifying agent addition process. The solidifying agent addition process involves adding a solidifying agent to the soil. Furthermore, the polymer modifier and other components such as solidifying agents may be added to the mud simultaneously, or each component may be added separately. [Examples]

[0062] Next, the present invention will be described with reference to examples, but the scope of the present invention is not limited to these examples.

[0063] 1. Viscosity of polymer modifiers The types and viscosities of the polymer modifiers used in the examples are shown in Table 1 below.

[0064] [Table 1]

[0065] All of the polymer modifiers mentioned above are manufactured by SNF Corporation. The structures of the anionic polymer modifier and the amphoteric polymer modifier used in the examples are shown below. Note that the polymer modifiers in the table are water-in-oil emulsions.

[0066] [ka] Here, R1 is H or CH3, R4 is selected from Na, K, or NH3, and l, m, and n each represent an integer greater than or equal to 0. In anionic polymer modifiers, n>0 and n>m, and in amphoteric polymer modifiers, n>0, m>0, and n=m.

[0067] The bulk viscosity and viscosity in a 0.5% mass aqueous solution shown in Table 1 were measured as follows.

[0068] <Method for measuring bulk viscosity (viscosity in emulsion state)> The polymer modifier in emulsion form (as it is sold) was measured using a Brookfield viscometer with spindle No. 3 at 30 rpm and 25°C.

[0069] <Method for measuring viscosity in a 0.5% by mass aqueous solution> The viscosity of a 0.5 mass% aqueous solution was measured at 25°C using a Brookfield viscometer, with spindle No. 2 rotated at 60 rpm until the reading stabilized.

[0070] 2. Changes in the time required to modify mud using polymer modifiers. (Examples 1-2, Comparative Example 1) A sandy soil with a fine-grained content of 19.1% and a water content of 4.8% was used as the soil sample. 60 kg / m³ was added to this soil sample. 3 Bentonite slurry concentration 350 L / m 3 , and water 100 L / m³ 3The mixture was added and stirred in a soil mixer to produce mud. The polymer modifiers listed in Table 2 were added to the prepared mud at a rate of 1.5 kg / m³ relative to the volume of the mud. 3 After adding the mixture and stirring it in a soil mixer, improved soil containing the soil modifier was obtained. The performance of the soil modifier was evaluated by its fluidity value. Specifically, improved soil mixed in a soil mixer for 5 seconds, 10 seconds, or 15 seconds was subjected to a table flow test. The table flow test was conducted in accordance with "12 Flow Test" (http: / / kikakurui.com / r5 / R5201-2015-01.html) of "Physical Test Methods for Cement" (JIS R5201). Specifically, the sample soil was packed in two layers into a flow cone placed in the center of a flow table. The entire surface of each layer was tamped 50 times with a tamping rod, and the sample soil was added as needed to level the surface. Immediately afterward, the flow cone was removed vertically and subjected to a drop motion 50 times at a frequency of once per second. The maximum diameter after the sample soil had spread and the diameter extending in the direction perpendicular to the maximum diameter were measured, and the average of the two values ​​was calculated. The test was performed twice, and the average value was taken as the table flow value (TF value). The measurement results are shown in Table 2.

[0071] [Table 2]

[0072] The TF values ​​for the sample soil, bentonite slurry, and slurry containing only water (slurry without polymer modifiers) were 231 mm. In both Examples 1 and 2 and Comparative Example 1, the TF values ​​tended to decrease with increasing stirring time. For mud to be transportable by truck or the like, the fluidity is such that the TF (Turf Fluid) is 150 mm or less. Comparing the time it takes to reach this TF value, in Examples 1 and 2, the TF value was 150 mm or less after 10 seconds of stirring, whereas in Comparative Example 1, the TF value did not drop to 150 mm even after 15 seconds of stirring. Therefore, it became clear that mud modifiers containing the polymer modifiers of Examples 1 and 2, i.e., polymer modifiers where (viscosity in emulsion state) - (viscosity in 0.5 mass% aqueous solution) > 0, can reduce the fluidity of mud in a short time.

[0073] 3. Changes in the amount of polymer modifier added and the time it takes to modify the soil. (Examples 3-6, Comparative Examples 2-3) A sandy soil with a fine-grained content of 19.1% and a water content of 4.8% was used as the soil sample. 60 kg / m³ was added to this soil sample. 3 Bentonite slurry concentration 350 L / m 3 , and water 100 L / m³ 3 The mixture was added and stirred in a soil mixer to produce mud. The amount of polymer modifier shown in Table 3 was added to the prepared mud and stirred in a soil mixer for 15 seconds to obtain improved soil containing the mud modifier. The improved soil obtained was subjected to a table flow test using the same method as in Example 1. The measurement results are shown in Table 3.

[0074] [Table 3]

[0075] For mud to be transportable by truck or the like, the TF value should be 150 mm or less. In Examples 3 to 6, the TF value was 150 mm or less, whereas in Comparative Examples 2 and 3, the TF value did not fall below 150 mm even when the amount of additive was increased. Therefore, it was found that a mud modifier containing a polymer modifier where (viscosity in emulsion state) - (viscosity in 0.5 mass% aqueous solution) > 0 can reduce the mud's fluidity in a short time, even with a small amount of additive.

[0076] 4. Addition of polymer modifiers and changes in soil strength (Examples 7-9, Comparative Examples 4-5) As the soil sample, a clayey soil with a fine-grained content of 50% and a water content of 36.5% was used. A foaming agent (Leoform OL-10, manufactured by Lion Specialty Chemicals Co., Ltd.) was added to the clayey soil to a concentration of 1% by mass, and the mixture was stirred and mixed in a pan-type mixer (1.5 minutes x 2 times). The foaming agent used was adjusted to achieve a foaming ratio of 10 times when added. Here, "foaming ratio" refers to the volume ratio of the volume of foaming agent after foaming to the volume of the diluted solution. Subsequently, 8 kg / m³ of the polymer modifiers of the types listed in Table 4 were added. 3 The mixture was added and mixed by hand stirring (1 minute) to produce improved soil containing the soil modifier. The cone index (Qc) of the prepared improved soil was measured. The cone index was measured in accordance with JIS A 1228. The measurement results are shown in Table 4.

[0077] [Table 4]

[0078] The cone index is 240 kN / m 2 or more (200kN / m 2 ×Construction safety factor 1.2=240kN / m 2 If so, it can be said that the mud was given an appropriate firmness. The cone index for Examples 7-9 is 240 kN / m 2 In contrast to the above, the cone index of Comparative Examples 4-5 is 240 kN / m 2 The results were as follows. From this, it became clear that a soil modifier containing a polymer modifier where (viscosity in emulsion state) - (viscosity in 0.5 mass% aqueous solution) > 0 can impart appropriate firmness to soil in a short time.

Claims

1. A soil modifier characterized by containing a polymer modifier that satisfies the following conditions. (conditions) (Viscosity in emulsion state) - (Viscosity in 0.5% by mass aqueous solution) > 0

2. The soil modifier according to claim 1, wherein the viscosity of the polymer modifier in the emulsion state is 500 cps or less.

3. The method for treating mud according to claim 1 or 2, wherein the viscosity of a 0.5% by mass aqueous solution of the polymer modifier is 500 cps or less.

4. A method for treating mud, characterized by mixing mud with a mud modifier containing a polymer modifier that satisfies the following conditions. (conditions) (Viscosity in emulsion state) - (Viscosity in 0.5% by mass aqueous solution) > 0

Images