JP2012240903A - Fluidizing agent for soil cement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluidizing agent capable of giving excellent fluidity to soil cement without being affected by the kind of soil.SOLUTION: A fluidizing agent for soil cement includes a polymer composition (A), which is prepared by neutralizing a (co)polymer containing α, β-unsaturated carboxylic acid as an essential constituent monomer with an alkaline earth metal hydroxide and/or an alkaline earth metal carbonate of 0.35-1 mol per mol of the carboxyl group of the (co)polymer; and an inorganic compound (B) that is at least one selected from the group consisting of an alkali metal carbonate, alkaline earth metal carbonate, alkali metal silicate, alkaline earth metal silicate, alkali metal hydroxide, and alkaline earth metal hydroxide.

Description

  The present invention relates to a fluidizing agent for soil cement.

Conventionally, as a fluidizing agent for soil cement, a low molecular weight polymer having a weight average molecular weight of 25,000 or less and an alkali metal carbonate having a carboxylic acid or a monovalent salt as a main unit monomer unit, and the above low molecular weight polymer and A fluidizing agent in which the ratio of the amount of the alkali metal carbonate to the total weight of the alkali metal carbonate is 50 to 95% by weight is known (Patent Document 1).
Also known is a fluidizing agent comprising a polymer compound having a carboxylic acid group, wherein the carboxylic acid group of the polymer compound is neutralized with an alkaline earth metal in an equivalent amount of 10 to 80%. (Patent Document 2).

Japanese Patent No. 3554496 JP 2001-172629 A

However, the conventional fluidizing agent may not have sufficient fluidity depending on the type of soil.
That is, an object of the present invention is to provide a fluidizing agent that can impart excellent fluidity to soil cement without being affected by the type of soil.

As a result of intensive studies to solve these problems, the present inventor has reached the present invention.
That is, the feature of the soil cement fluidizing agent of the present invention is that a (co) polymer having an α, β-unsaturated carboxylic acid as an essential constituent monomer is converted to 0 per mol of the carboxyl group of the (co) polymer. Polymer composition (A) neutralized with 35 to 1 mol of alkaline earth metal hydroxide and / or alkaline earth metal carbonate, alkali metal carbonate, alkaline earth metal carbonate, alkali metal silicic acid The gist of the invention is that it comprises at least one inorganic compound (B) selected from the group consisting of a salt, an alkaline earth metal silicate, an alkali metal hydroxide, and an alkaline earth metal hydroxide.

  A feature of the method for producing a soil cement structure according to the present invention is that it includes a fluidizing step of fluidizing the soil cement by applying the above-described fluidizing agent for soil cement to the soil cement.

The fluidizing agent for soil cement of the present invention can impart excellent fluidity to the soil cement without being affected by the type of soil.
According to the method for producing a soil cement structure of the present invention, since the above-described fluidizing agent for soil cement is used, it is possible to impart excellent fluidity to the soil cement without being affected by the type of soil. A strong soil cement structure can be easily obtained.

<Polymer composition (A)>
As the α, β-unsaturated carboxylic acid that is an essential monomer constituting the (co) polymer, (meth) acrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid And citraconic anhydride and the like. Two or more of these may be used in combination. Of these, (meth) acrylic acid, maleic acid, fumaric acid and itaconic acid are preferred, more preferably (meth) acrylic acid, maleic acid and itaconic acid, particularly preferably (meth) acrylic acid and maleic acid, and more particularly (Meth) acrylic acid is preferred, and acrylic acid is most preferred.

  As a constituent unit of the (co) polymer, other copolymerizable monomers can be used. The other monomer is not particularly limited as long as it can be copolymerized with an α, β-unsaturated carboxylic acid, and is an unsaturated carboxylic acid ester having 4 to 20 carbon atoms, a fatty acid vinyl ester having 4 to 20 carbon atoms, or 2 carbon atoms. -20 olefins, C3-C5 unsaturated nitriles, C2-C8 unsaturated amides, C5-C60 unsaturated ethers, and the like can be used.

  As unsaturated carboxylic acid ester, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, (meth) acrylic acid Examples include benzyl, methyl crotonate, dimethyl maleate, hexyl maleate and butyl itaconate.

  Examples of the fatty acid vinyl ester include vinyl acetate, vinyl palmitate, vinyl laurate, and vinyl stearate.

  Examples of olefins include α-olefins (ethylene, propylene, butylene, hexylene, octylene, undecylene, tetradecylene, and nonadecylene), diisobutylene, butadiene, piperylene, chloroprene, pinene, limonene, indene, cyclopentadiene, bicyclopentadiene, and ethylidene norbornene. Etc.

  Examples of unsaturated nitriles include (meth) acrylonitrile, cyanopropene and cyanopentene.

  As unsaturated amides, (meth) acrylamide, N-methyl (meth) acrylamide, N-2-hydroxymethyl (meth) acrylamide, N- (2-aminoethyl) (meth) acrylamide and N- (2-dimethylamino) Ethyl) (meth) acrylamide and the like.

  Examples of unsaturated ethers include methoxypolyethylene glycol (degree of polymerization 25) (meth) acrylate, methoxypolyethylene glycol (degree of polymerization 5) (meth) acrylate, polyethylene glycol (degree of polymerization 20) mono (meth) acrylate and polyethylene glycol (degree of polymerization). 10) Mono (meth) acrylate and the like.

  Of these other monomers, unsaturated carboxylic acid esters and unsaturated nitriles are preferable, unsaturated nitriles are more preferable, and acrylonitrile is particularly preferable.

  When other monomers are contained as constituent monomers, the content (mol%) of other monomer units is the number of moles of α, β-unsaturated carboxylic acid units and other monomer units. Based on this, it is preferably 0.1-50, more preferably 0.2-30, particularly preferably 0.3-10, and most preferably 0.5-3. Within this range, the fluidity of the soil cement is further improved.

  When other monomer is contained as a constituent monomer, the content (mol%) of the α, β-unsaturated carboxylic acid unit is the same as that of the α, β-unsaturated carboxylic acid unit and the other monomer unit. Based on the number of moles, 50 to 99.9 is preferable, more preferably 70 to 99.8, particularly preferably 90 to 99.7, and most preferably 97 to 99.5. Within this range, the fluidity of the soil cement is further improved.

  In the polymer composition (A), the above (co) polymer is neutralized with an alkaline earth metal hydroxide and / or an alkaline earth metal carbonate. The degree of neutralization is 0.35 to 1 mol, preferably 0.40 to 0.9 mol, more preferably 0.45 to 0.75 mol, per mol of carboxyl group in the (co) polymer. Particularly preferably, the amount is 0.5 to 0.65 mol. Within this range, the fluidity of the soil cement is further improved. In addition, when the above range is exceeded, the blending effect is saturated, the fluidity of the soil cement is hardly improved, and the strength of the soil cement structure may be lowered.

  Examples of the alkaline earth metal hydroxide include beryllium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide and barium hydroxide. Examples of the alkaline earth metal carbonate include beryllium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, and barium carbonate. You may use these individually or in mixture. Of these, beryllium hydroxide, magnesium hydroxide, calcium hydroxide, beryllium carbonate, magnesium carbonate and calcium carbonate are preferable, more preferably magnesium hydroxide, calcium hydroxide, magnesium carbonate and calcium carbonate, and particularly preferably magnesium hydroxide. And magnesium carbonate, most preferably magnesium hydroxide.

  Neutralization of the (co) polymer may be carried out with alkaline earth metal hydroxide alone or alkaline earth metal carbonate alone, or any of alkaline earth metal hydroxide and alkaline earth metal carbonate may be used. It may be neutralized after mixing in proportions, or the (co) polymers may be neutralized individually to obtain at least two kinds of neutralized products and then mixed. In addition, the α, β-unsaturated carboxylic acid is neutralized with an alkaline earth metal hydroxide and / or alkaline earth metal carbonate, and then (co) polymerized to obtain a polymer composition (A). Or a portion of the α, β-unsaturated carboxylic acid may be neutralized with an alkaline earth metal hydroxide and / or alkaline earth metal carbonate and then (co) polymerized to form the remaining The polymer composition (A) may be obtained by neutralizing the α, β-unsaturated carboxylic acid unit with an alkaline earth metal hydroxide and / or an alkaline earth metal carbonate.

  The (co) polymer can be obtained by using a usual polymerization method of vinyl monomers. As the polymerization method, suspension polymerization, bulk polymerization, solution polymerization and the like can be applied. From the viewpoint of productivity, solution polymerization can be performed. preferable.

  A polymerization catalyst can be used for the polymerization. As the polymerization catalyst, an ordinary polymerization catalyst or the like is used, and azo compounds, persulfates, inorganic peroxides, redox catalysts, organic peroxides, and the like are included. Examples of the azo compound include 2,2′-azobisisobutyronitrile, 4,4′-azobis-4-cyanovaleric acid, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile, 2, 2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1-albonitrile), 2,2'-azobis (2,4,4-trimethylpentane), dimethyl 2,2 ' -Azobis (2-methylpropionate), 2,2'-azobis [2- (hydroxymethyl) propionitrile], 1,1'-azobis (1-acetoxy-1-phenylethane) and the like. Examples of the salt include ammonium persulfate, potassium persulfate, sodium persulfate, etc. Examples of the inorganic peroxide include perborate and hydrogen peroxide. Examples of the redox catalyst include ascorbic acid-hydrogen peroxide, etc. Examples of the organic peroxide include benzoyl peroxide, etc. These polymerization catalysts may be used alone or in combination. Of these, persulfates and azo compounds are preferred, more preferred are persulfates and 2,2′-azobisisobutyronitrile, and particularly preferred are ammonium persulfate, potassium persulfate, and sodium persulfate.

  When a polymerization catalyst is used, the amount (% by weight) of the polymerization catalyst is preferably 0.01 to 100, more preferably 0.1 to 80, and particularly preferably 0. 0 based on the weight of the constituent monomer. 5-50.

  In the case of solution polymerization and suspension polymerization, the solvent includes water (tap water, ion exchange water, industrial water, etc.), alcohol solvent (methanol, ethanol, isopropyl alcohol, etc.) and / or aromatic solvent (toluene, xylene, etc.). Etc. can be used. Among these, water, a mixed solvent of water and an alcohol solvent are preferable, a mixed solvent of water and alcohol is more preferable, and a mixed solvent of ion-exchanged water and isopropyl alcohol is particularly preferable.

  When a solvent is used, the amount (% by weight) used is preferably 50 to 900, more preferably 60 to 800, and particularly preferably 100 to 600, based on the total weight of the constituent monomers.

  The polymerization reaction temperature is preferably about 40 to 130 ° C., and the polymerization reaction time is preferably about 1 to 15 hours.

  In addition, you may superpose | polymerize, dripping the whole quantity or one part of a structural monomer. Moreover, you may superpose | polymerize, dripping the whole quantity or one part of a polymerization catalyst. Moreover, you may superpose | polymerize, dripping the whole quantity or one part of a solvent with a structural monomer or a polymerization catalyst. On the other hand, the entire amount of the solvent may be charged in a polymerization tank and polymerization may be performed while removing the solvent. Among these, from the viewpoint of productivity and the like, the method of dropping the whole amount of the constituent monomer and the polymerization catalyst and the method of dropping a part of the solvent together with the constituent monomer or the polymerization catalyst are preferable, and more preferably the constituent unit. In this method, the entire amount of the monomer and the polymerization catalyst is dropped together with a part of the solvent.

  The polymer composition (A) is converted to an alkaline earth metal salt by neutralizing the (co) polymer with an alkaline earth metal hydroxide and / or an alkaline earth metal carbonate. It is preferable not to contain a metal salt. That is, it is preferable not to contain an alkali metal hydroxide or alkali metal carbonate as a neutralizing agent.

  The weight average molecular weight (Mw) of the polymer composition (A) is preferably 4,000 to 40,000, more preferably 6,000 to 30,000, and particularly preferably 8,000 to 25,000. The molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) is preferably 1 to 3, more preferably 1 to 2.5, and particularly preferably 1 to 2. Within these ranges, the fluidity of the soil cement is further improved.

  The weight average molecular weight (Mw) and number average molecular weight (Mn) are measured by a gel permeation chromatography (GPC) method using (poly) ethylene glycol having a known molecular weight as a standard substance (column temperature 40 ° C., elution). Liquid: 0.1-MPB disodium hydrogen phosphate aqueous solution: 0.1-MPB sodium dihydrogen phosphate aqueous solution = 1: 1 (molar ratio), flow rate 0.8 ml / min, sample concentration: 0.4 wt% Eluent solution).

The form of the polymer composition (A) is not particularly limited, and may be liquid or solid.
The liquid polymer composition (A) means a state in which the polymer composition (A) is dissolved or dispersed in an aqueous solvent. In this case, the polymer composition (A) may be obtained by suspension polymerization or solution polymerization without removing all of the solvent, or the polymer composition (A) obtained by bulk polymerization or the like may be obtained as an aqueous solvent. It may be obtained by dissolving or dispersing in.
Examples of the aqueous solvent include water, alcohols having 1 to 6 carbon atoms (such as ethyl alcohol, methyl alcohol, ethylene glycol and diethylene glycol), and ketones having 1 to 6 carbon atoms (such as methyl isobutyl ketone and acetone). They may be used alone or in combination.

On the other hand, when the polymer composition (A) is solid, it may be a solid composed of the polymer composition (A), or a powder having the liquid polymer composition (A) supported on the powder. May be.
In the case of a solid comprising the polymer composition (A), it may be obtained by bulk polymerization, or after obtaining a solution or dispersion containing the polymer composition (A) by suspension polymerization or solution polymerization, the solvent is removed. You may obtain by removing.
As a method for removing the solvent from the solution or dispersion containing the polymer composition (A), known methods such as a dry pulverization method, a freeze pulverization method, a spray dryer method, and a drum dryer method can be used. Of these, the dry pulverization method and the spray dryer method are preferred.
The size (mm; maximum length) of the solid polymer composition (A) is preferably from 0.01 to 5, more preferably from 0.05 to 5 from the viewpoint of the solubility of the fluidizing agent of the present invention. 3, particularly preferably 0.08 to 1.
When the liquid polymer composition (A) is supported on a powder, examples of the powder include activated carbon, calcium carbonate, silica, zeolite, shirasu balloon, and bentonite.
As a method for supporting the liquid polymer composition (A) on these powders, the powder and the liquid polymer composition (A) can be used by using a known stirring mixer (such as a ribbon mixer and a Henschel mixer). And the like can be applied.
Among the forms of the polymer composition (A), a liquid form is preferable, and a state where the polymer composition (A) is dissolved in an aqueous solvent is more preferable.

<Inorganic compound (B)>
Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, potassium carbonate, lithium hydrogen carbonate, sodium hydrogen carbonate, and potassium hydrogen carbonate.

  Examples of the alkaline earth metal carbonate include magnesium carbonate, calcium carbonate, barium carbonate, magnesium hydrogen carbonate, and calcium hydrogen carbonate.

  Alkali metal silicates include lithium orthosilicate, lithium metasilicate, lithium metasilicate hydrate, hexalithium orthodisilicate, sodium orthosilicate, sodium metasilicate, sodium metasilicate hydrate, sodium disilicate, potassium orthosilicate And potassium metasilicate.

  Examples of the alkaline earth metal silicate include magnesium orthosilicate, calcium metasilicate, magnesium silicate hydrate and the like.

  Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide.

  Examples of the alkaline earth metal hydroxide include magnesium hydroxide, calcium hydroxide and barium hydroxide.

  Of these, alkali metal carbonates, alkaline earth metal carbonates, alkali metal hydroxides and alkaline earth metal hydroxides are preferable, and sodium carbonate, sodium hydrogen carbonate, and magnesium hydroxide are more preferable.

  When the polymer composition (A) is neutralized with an alkaline earth metal hydroxide, the inorganic compound (B) preferably contains an inorganic compound other than the alkaline earth metal hydroxide. On the other hand, when the polymer composition (A) is neutralized with an alkaline earth metal carbonate, the inorganic compound (B) preferably contains an inorganic compound other than the alkaline earth metal carbonate. Further, when the polymer composition (A) is neutralized with an alkaline earth metal hydroxide and an alkaline earth metal carbonate, the inorganic compound (B) may be an alkaline earth metal hydroxide or an alkaline earth. It is preferable to contain an inorganic compound other than the alkali metal carbonate.

  The content (% by weight) of the inorganic compound (B) is preferably 90 to 2500, more preferably 100 to 2000, and particularly preferably 200 to 1500, based on the weight of the polymer composition (A). Within this range, the influence on the curability of the soil cement is small, and the fluidity is further improved.

  The form of the inorganic compound (B) is not particularly limited and may be liquid or solid. The liquid inorganic compound (B) means a state in which the inorganic compound (B) is dissolved or dispersed in an aqueous solvent. In this case, as the inorganic compound (B), a liquid product may be purchased from the market, or a solid product may be purchased and dissolved or dispersed in an aqueous solvent.

On the other hand, when the inorganic compound (B) is solid, it may be a solid composed of the inorganic compound (B), or may be a powder in which the inorganic compound (B) is supported on a powder.
In the case of a solid comprising the inorganic compound (B), a solid product may be purchased from the market, or may be obtained by removing the solvent from the liquid product purchased from the market.
The method for removing the solvent from the solution or dispersion containing the inorganic compound (B) is the same as in the case of the polymer composition (A) including preferable ones.
The size (mm; maximum length) of the solid inorganic compound (B) is preferably 0.01 to 10, more preferably 0.05 to 8, from the viewpoint of the solubility of the fluidizing agent of the present invention. Especially preferably, it is 0.08-5.
When the liquid inorganic compound (B) is supported on the powder, the powder and the supporting method are the same as in the case of the polymer composition (A).
Among the forms of the inorganic compound (B), solid is preferable, and solid is more preferable.

For the fluidizing agent of the present invention, known additives used together with cement (AE agent, AE water reducing agent, high performance water reducing agent, retarder, early strength agent, curing accelerator, foaming agent, foaming agent, antifoaming agent) Agents, quick setting agents, swelling agents, thickeners, waterproofing agents, and the like). These may be used alone or in combination.
When the additive is contained, the content (% by weight) is preferably 1 to 30, more preferably 2 to 15, based on the total weight of the polymer composition (A) and the inorganic compound (B). Especially preferably, it is 3-10.
The fluidizing agent of the present invention can contain an aqueous solvent or the like. When a water-soluble solvent is contained, the content (% by weight) is added from the viewpoint of handling properties (viscosity, etc.) of the fluidizing agent, the polymer composition (A), the inorganic compound (B), and if necessary. 70 to 2,000, preferably 80 to 1,000, and particularly preferably 90 to 500, based on the total weight of additives.

  The form of the fluidizing agent of the present invention is (1) a form in which the polymer composition (A) and the inorganic compound (B) are present together (which may be liquid or solid), or (2) the polymer composition. Form in which (A) and inorganic compound (B) exist separately (each may be liquid or solid. Each is mixed at the time of use, but may be added to soil cement after mixing, or soil Any of the above may be added after mixing with cement). In addition, in the case of (2), the additive and / or water contained as necessary may be included in each or in any case.

The fluidizing agent of the present invention is preferably added to and mixed with cement slurry and then mixed with excavated soil to form soil cement.
The cement slurry is obtained by mixing cement and water.
Examples of the cement include Portland cement (ordinary Portland cement, early-strength Portland cement, super early-strength Portland cement, moderately hot Portland cement, sulfate-resistant Portland cement, etc .; JIS R5210: 2003), blast furnace cement (JIS R5211: 2003), silica Cement (JIS R5212-1997), fly ash cement (JIS R5213-1997), etc. are mentioned. These cements can be used as one or a mixture of two or more, and in addition, these cements are used in combination with known cement admixtures such as blast furnace slag fine powder, fly ash, silica fume and lime-based solidifying material. May be. Of these, Portland cement is preferable from the viewpoint of availability.

  The content (% by weight) of water contained in the cement slurry is preferably 50 to 400, more preferably 60 to 350, and particularly preferably 70 to 300, based on the weight of the cement.

  The amount of the fluidizing agent of the present invention is preferably such that the total weight of the polymer composition (A) and the inorganic compound (B) is 0.1 to 60, more preferably based on the weight of the cement. It is 0.3 to 30, particularly preferably 0.4 to 20.

There is no restriction on excavated soil, and excavated soil containing coarse-grained soil can be used regardless of the amount of clay in the soil.
The content (% by weight) of excavated soil contained in the soil cement is preferably 120 to 2400, more preferably 200 to 1500, and particularly preferably 250 to 1200, based on the weight of the cement.

  For soil cement, if necessary, known additives used together with cement (AE agent, AE water reducing agent, high performance water reducing agent, retarder, early strengthening agent, accelerator, foaming agent, foaming agent, Antifoaming agent, quick setting agent, swelling agent, thickener, waterproofing agent, bentonite, etc.) can be added, and these may be used alone or in combination. When these additives are included, the amount of these additives is the same as in a normal case.

A soil cement structure can be obtained by preparing soil cement at a construction site, placing it, and hardening it.
The method for producing the soil cement structure is not limited as long as it includes a fluidizing step of fluidizing the soil cement by applying the above-mentioned fluidizing agent for soil cement to the soil cement. For example, both functions of excavation and kneading are provided. A method for obtaining a soil cement structure after curing, by kneading the cement slurry and excavated soil in the ground using an excavator kneading machine provided with a cement slurry discharge port at the tip of the excavator, or Examples include a method of kneading cement slurry and excavated soil on the ground, then placing the slurry at an excavation site, and obtaining a soil cement structure after curing (Japanese Patent Application Laid-Open No. 2000-169209 for a more detailed method for producing a soil cement structure). This is the same as the method described in the publication.

  The following examples further illustrate the invention, but the invention is not limited thereto. Unless otherwise specified, parts represent parts by weight and% represents% by weight.

<Production Example 1>
200 parts of ion-exchanged water and 300 parts of isopropyl alcohol are put into a pressure-resistant reaction vessel equipped with a dropping line, a stirrer, and a thermometer. The reaction was carried out in a sealed manner while dropping from each separate dropping line at a constant rate over 3 hours. The reaction temperature was maintained at 80-100 ° C. After maintaining the temperature at 95-100 ° C. for 3 hours after completion of the dropping, the isopropyl alcohol was removed under reduced pressure while adding 150 parts of ion-exchanged water dropwise (watering), and then cooled to 30 ° C. While keeping, 117 parts (2 mole parts) of magnesium hydroxide [reagent special grade, manufactured by Wako Pure Chemical Industries, Ltd.] was gradually added. Then, the concentration was adjusted to 15% by adding water to obtain a polymer composition (A1) [neutralized 0.5 mol of magnesium per mol of carboxyl group of acrylic acid unit]. The polymer composition (A1) had a weight average molecular weight of 14,000 and a molecular weight distribution (Mw / Mn) of 1.4.

<Production Example 2>
Except having changed magnesium hydroxide from 117 parts (2 mol parts) to 152 parts (2.6 mol parts), in the same manner as in Production Example 1, the polymer composition (A2) [carboxyl group 1 of acrylic acid unit 1 0.65 mol neutralized product of magnesium per mol] was obtained. The polymer composition (A2) had a weight average molecular weight of 14,000 and a molecular weight distribution of 1.4.

<Production Example 3>
“288 parts (4 moles) of acrylic acid” was changed to “279 parts (3.9 moles) of acrylic acid and 10.4 parts (0.1 moles) of methyl acrylate”, “magnesium hydroxide 117 Part (2 mole parts) "was changed to" calcium hydroxide [reagent special grade, manufactured by Wako Pure Chemical Industries, Ltd.] 216 parts (2.9 mole parts) ". Molecular composition (A3) [0.74 mol neutralized product of calcium per mol of carboxyl group of acrylic acid unit] was obtained. The polymer composition (A3) had a weight average molecular weight of 13,000 and a molecular weight distribution of 1.3.

<Production Example 4>
“Acrylic acid 288 parts (4 mole parts)” was changed to “methacrylic acid 310 parts (3.6 mole parts) and acrylonitrile 21 parts (0.4 mole parts)”, “magnesium hydroxide 117 parts (2 moles) Part) ”was changed to“ 167 parts (2 mole parts) of magnesium carbonate [special grade reagent, Wako Pure Chemical Industries, Ltd.] ”in the same manner as in Production Example 1, except that the polymer composition (A4) [ A 0.56 mol neutralized product of magnesium per 1 mol of carboxyl groups of methacrylic acid units] was obtained. The polymer composition (A4) had a weight average molecular weight of 20,000 and a molecular weight distribution of 1.7.

<Production Example 5>
“288 parts (4 moles) acrylic acid” was changed to “236 parts (3.3 moles) acrylic acid and 38 parts (0.7 moles) acrylonitrile”; 117 parts magnesium hydroxide (2 moles) Part) ”was changed to“ 96 parts of magnesium hydroxide (1.6 moles) ”in the same manner as in Production Example 1, except that the polymer composition (A5) [magnesium per mole of carboxyl groups of acrylic acid units] 0.48 mol neutralized product] was obtained. The polymer composition (A5) had a weight average molecular weight of 21,000 and a molecular weight distribution of 1.7.

<Production Example 6>
“Acrylic acid 288 parts (4 mole parts)” was changed to “Acrylic acid 202 parts (2.8 mole parts) and acrylonitrile 64 parts (1.2 mole parts)”, “Magnesium hydroxide 117 parts (2 moles) Part) ”was changed to“ 104 parts by weight of calcium hydroxide (1.4 mole parts) ”in the same manner as in Production Example 1, except that the polymer composition (A6) [calcium per mole of carboxyl groups of acrylic acid units] 0.5 molar neutralized product] was obtained. The polymer composition (A6) had a weight average molecular weight of 25,000 and a molecular weight distribution of 2.1.

<Production Example 7>
“Acrylic acid 288 parts (4 mole parts)” was changed to “methacrylic acid 189 parts (2.2 mole parts) and methyl acrylate 155 parts (1.8 mole parts)”, “magnesium hydroxide 117 parts ( 2 mol parts) ”was changed to“ 186 parts magnesium carbonate (2.2 mol parts) ”in the same manner as in Production Example 1, but the polymer composition (A7) [per carboxylic acid unit carboxyl group per methacrylic acid unit] 1 mol neutralized product of magnesium] was obtained. The polymer composition (A7) had a weight average molecular weight of 18,000 and a molecular weight distribution of 1.5.

<Production Example 8>
“Acrylic acid 288 parts (4 mole parts)” was changed to “acrylic acid 144 parts (2 mole parts) and methyl acrylate 172 parts (2 mole parts)”, “magnesium hydroxide 117 parts (2 mole parts) ”In the same manner as in Production Example 1, except that the calcium carbonate [reagent special grade, manufactured by Wako Pure Chemical Industries, Ltd.] 180 parts (1.8 mole parts)” was changed. 0.9 mol neutralized product of calcium per mol of carboxyl group of acrylic acid unit] was obtained. The polymer composition (A8) had a weight average molecular weight of 16,000 and a molecular weight distribution of 1.5.

<Production Example 9>
“Acrylic acid 288 parts (4 mole parts)” was changed to “acrylic acid 115 parts (1.6 mole parts) and acrylonitrile 127 parts (2.4 mole parts)”, “magnesium hydroxide 117 parts (2 moles) Part) ”was changed to“ 80 parts calcium carbonate (0.8 mole part) ”in the same manner as in Production Example 1, except that the polymer composition (A9) [calcium 0 per mole of carboxyl group of acrylic acid unit .5 molar neutralized product] was obtained. The polymer composition (A9) had a weight average molecular weight of 30,000 and a molecular weight distribution of 2.6.

<Production Example 10>
“Acrylic acid 288 parts (4 mol parts)” was changed to “acrylic acid 230 parts (3.2 mol parts) and methacrylic acid 69 parts (0.8 mol parts)”, “magnesium hydroxide 117 parts (2 Mol part) ”was changed to“ 175 parts of magnesium hydroxide (3 mol parts) ”, and the polymer composition (A10) [total carboxyl groups of acrylic acid units and methacrylic acid units was obtained in the same manner as in Production Example 1. 0.75 mol neutralized product of magnesium per mol] was obtained. The polymer composition (A10) had a weight average molecular weight of 15,000 and a molecular weight distribution of 1.5.

<Production Example 11>
“288 parts (4 moles) of acrylic acid” was changed to “202 parts (2.8 moles) of acrylic acid and 139 parts (1.2 moles) of maleic acid”, “117 parts of magnesium hydroxide (2 Mol part) ”was changed to“ magnesium hydroxide 303 parts (5.2 mol parts) ”in the same manner as in Production Example 1, but the polymer composition (A11) [carboxyl of acrylic acid units and maleic acid units] 1 mol of magnesium neutralized product per 1 mol of the total group]. The polymer composition (A11) had a weight average molecular weight of 16,000 and a molecular weight distribution of 1.4.

<Production Example 12>
“288 parts (4 moles) of acrylic acid” was replaced with “259 parts (3.6 moles) of acrylic acid, 17.2 parts (0.2 moles) of methyl acrylate and 10.8 parts (0.2 moles) of acrylonitrile. Parts) ”, and“ magnesium hydroxide 117 parts (2 mole parts) ”was changed to“ calcium hydroxide 173 parts (2.3 mole parts) ”. Molecular composition (A12) [0.6 mol neutralized product of calcium per mol of carboxyl group of acrylic acid unit] was obtained. The polymer composition (A12) had a weight average molecular weight of 17,000 and a molecular weight distribution of 1.6.

<Production Example 13>
Changed “288 parts of acrylic acid (4 moles)” to “173 parts of acrylic acid (2.4 moles), 52 parts of itaconic acid (0.4 moles) and 64 parts of acrylonitrile (1.2 moles)” In the same manner as in Production Example 1, except that “magnesium hydroxide 117 parts (2 mole parts)” was changed to “magnesium carbonate 135 parts (1.6 mole parts)”, the polymer composition (A12) [A neutralized product of 0.5 mol of magnesium per 1 mol of total carboxyl groups of acrylic acid units and itaconic acid units]. The polymer composition (A13) had a weight average molecular weight of 20,000 and a molecular weight distribution of 1.8.

<Production Example 14>
"288 parts of acrylic acid (4 moles)" was replaced with "72 parts of acrylic acid (1 mole), 116 parts of maleic acid (1 mole), 86 parts of methyl acrylate (1 mole) and 53 parts of acrylonitrile (1 mole). Parts) ”, and“ magnesium hydroxide 117 parts (2 mole parts) ”was changed to“ magnesium hydroxide 96 parts (1.7 mole parts) ”. Molecular composition (A14) [neutralized product of 0.57 mol of magnesium per 1 mol of total carboxyl groups of acrylic acid units and maleic acid units] was obtained. The polymer composition (A14) had a weight average molecular weight of 30,000 and a molecular weight distribution of 2.0.

<Production Example 15>
"Acrylic acid 288 parts (4 mole units)" was changed to "Maleic acid 232 parts (2 mole parts) and Acrylonitrile 106 parts (2 mole parts)", "Magnesium hydroxide 117 parts (2 mole parts)" The polymer composition (A15) [neutralization of 0.5 mol of calcium per mol of carboxyl groups of maleic acid units] was carried out in the same manner as in Production Example 1 except that it was changed to “148 parts of calcium hydroxide (2 mol)”. Thing]. The polymer composition (A15) had a weight average molecular weight of 26,000 and a molecular weight distribution of 2.2.

<Production Example 16>
Except for changing “magnesium hydroxide 117 parts (2 mole parts)” to “magnesium hydroxide 117 parts (2 mole parts) and calcium hydroxide 148 parts (2 mole parts)”, in the same manner as in Production Example 1, A polymer composition (A16) [neutralized product of 0.5 mol magnesium and 0.5 mol calcium per mol of carboxyl group of acrylic acid unit] was obtained. The polymer composition (A16) had a weight average molecular weight of 14,000 and a molecular weight distribution of 1.4.

<Production Example 17>
Polymer composition (A17) [acrylic] in the same manner as in Production Example 1, except that “117 parts (2 moles) of magnesium hydroxide” was changed to “82 parts (1.4 moles) of magnesium hydroxide”. A 0.35 mol neutralized product of magnesium per mol of the carboxyl group of the acid unit] was obtained.The polymer composition (A17) had a weight average molecular weight of 14,000 and a molecular weight distribution of 1.4.

<Production Example 18>
Polymer composition (A18) [acrylic] in the same manner as in Production Example 1, except that “117 parts (2 moles) of magnesium hydroxide” was changed to “94 parts (1.6 moles) of magnesium hydroxide”. 0.4 mol of magnesium neutralized per mol of carboxyl group of the acid unit] The weight average molecular weight of the polymer composition (A18) was 14,000, and the molecular weight distribution was 1.4.

<Comparative Production Example 1>
200 parts of ion-exchanged water and 300 parts of isopropyl alcohol are put into a pressure-resistant reaction vessel equipped with a dropping line, a stirrer, and a thermometer. The reaction was carried out in a sealed state while dropping from each separate dropping line at a constant rate over 2 hours. The reaction temperature was maintained at 80-100 ° C. After maintaining the temperature at 95-100 ° C. for 3 hours after completion of the dropping, the isopropyl alcohol was removed under reduced pressure while adding 150 parts of ion-exchanged water dropwise (watering), and then cooled to 30 ° C. While maintaining the temperature, 333 parts (4 mole parts) of a 48% aqueous sodium hydroxide solution was gradually added in portions. Then, the concentration was adjusted to 15% by adding water to obtain a comparative polymer composition (H1) [neutralized product of 1 mol of sodium per mol of carboxyl group of acrylic acid unit]. The comparative polymer composition (H1) had a weight average molecular weight of 14,000 and a molecular weight distribution of 1.4.

<Comparative Production Example 2>
Comparative polymer composition in the same manner as Comparative Production Example 1, except that “333 parts (4 mole parts) of 48% aqueous sodium hydroxide solution” was changed to “70 parts (1.2 mole parts) of magnesium hydroxide”. (H2) [0.35 neutralized magnesium per mol of carboxyl group of acrylic acid unit] was obtained. The comparative polymer composition (H2) had a weight average molecular weight of 14,000 and a molecular weight distribution of 1.4.

  Using the polymer compositions (A1) to (A18) obtained in the production examples and the comparative polymer compositions (H1) to (H2) obtained in the comparative production examples, any of the following methods (regulation method A or An evaluation soil cement was prepared by the adjustment method B), and a fluidity test and a uniaxial compressive strength measurement were performed on the evaluation soil cement. The results are shown in Tables 3 to 5.

<Soil cement adjustment>
<Adjustment method A>
At each blending amount shown in Table 1, first, cement, bentonite, and clay were taken in a predetermined amount of mortar mixer [model: C138A-486, manufactured by Maruto Seisakusho], blended for 60 seconds, and then kneaded. An evaluation sample (polymer composition or comparative polymer composition) and an inorganic compound (B) were added with the remaining water shown in 1 and the respective compounding amounts shown in Table 2, kneaded for 90 seconds, and an evaluation soil. Cement was obtained.
Further, a blank soil cement was obtained in the same manner as described above except that the evaluation sample was not added and only the inorganic compound (B) was added.

<Adjustment method B>
At each blending amount shown in Table 1, first, cement, bentonite, and clay were taken in a predetermined amount of mortar mixer [model: C138A-486, manufactured by Maruto Seisakusho], blended for 60 seconds, and then kneaded. The remaining water shown in 1 was added and kneaded for an additional 30 seconds. Thereafter, in each compounding amount shown in Table 2, a sample prepared by previously mixing an evaluation sample (polymer composition or comparative polymer composition) and an inorganic compound (B) was added thereto, and kneaded for 60 seconds, followed by evaluation. A soil cement was obtained.
Further, a blank soil cement was obtained in the same manner as described above except that the evaluation sample was not added and only the inorganic compound (B) was added.

<Fluidity evaluation>
Acrylic resin cylindrical tube in which the soil cement for evaluation prepared as described above is vertically placed in the center of an acrylic plate (50 cm × 50 cm) (inner diameter: 5 cm × height: 5 cm, both ends of the cylindrical tube are open) Stuffed. Immediately after packing, this cylindrical tube was pulled up vertically and the spread of the soil cement in the horizontal direction (fluidity: flowability, unit: mm) was measured. Larger numbers indicate better fluidity and are better.

<Uniaxial compressive strength>
It consists of six vertically standing molds (an iron cylindrical tube with an inner diameter of 5 cm and a height of 10 cm, a removable bottom plate, and two semi-cylindrical parts (when two are combined, it becomes a cylinder with an inner diameter of 5 cm). } Was filled with the soil cement for evaluation immediately after production, and was subjected to air curing (3 in each) at 20 ° C. for 1 day and 28 days. Thereafter, the soil cement structure was removed from the mold, and the uniaxial compressive strength was measured in a room at 20 ° C. in accordance with JIS A1216: 1998, and the average value of the three was determined.

＊１ セメント：普通ポルトランドセメント、太平洋セメント（株）製
＊２ ベントナイト：関西ベントナイト（密度２．５１）、カサネン工業（株）製
＊３ 粘土は、以下の３種類のうち、いずれかを使用した。
（１）ＳＣＰ−Ａ（密度２．６１）、松下鉱産（株）製
（２）笠岡粘土（密度２．４５）、カサネン工業（株）製
（３）トチクレー（密度２．６６）、関東ベントナイト工業（株）製

* 1 Cement: Ordinary Portland Cement, Taiheiyo Cement Co., Ltd. * 2 Bentonite: Kansai Bentonite (Density 2.51), Kasanen Kogyo Co., Ltd. * 3 One of the following three types of clay was used. .
(1) SCP-A (density 2.61), made by Matsushita Mining Co., Ltd. (2) Kasaoka clay (density 2.45), made by Kasanen Kogyo Co., Ltd. (3) Tochi clay (density 2.66), Kanto bentonite Made by Kogyo Co., Ltd.

  Inorganic compound (B) {sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, sodium metasilicate} A reagent special grade manufactured by Yakugyo Co., Ltd. was used.

  The fluidizing agent of the present invention (Examples 1 to 22) is extremely superior in fluidity of the soil cement and can maintain the strength of the cement structure at a high level as compared with the fluidizing agent for soil cement for comparison.

  The fluidizing agent of the present invention is suitable for ground improvement such as landfill soil in which soil cement is used, soft ground reinforcement, and soil cement wall construction.

Claims (6)

A (co) polymer having an α, β-unsaturated carboxylic acid as an essential constituent monomer is mixed with 0.35 to 1 mol of an alkaline earth metal hydroxide per mol of the carboxyl group of the (co) polymer, and And / or polymer composition (A) neutralized with alkaline earth metal carbonate,
At least one inorganic compound selected from the group consisting of alkali metal carbonates, alkaline earth metal carbonates, alkali metal silicates, alkaline earth metal silicates, alkali metal hydroxides and alkaline earth metal hydroxides ( A fluidizing agent for soil cement, comprising B). The fluidizing agent according to claim 1, wherein the α, β-unsaturated carboxylic acid is at least one selected from the group consisting of (meth) acrylic acid, itaconic acid, maleic acid and fumaric acid. The fluidizing agent according to claim 1 or 2, wherein the content of the α, β-unsaturated carboxylic acid unit in the polymer composition (A) is 50 to 100 mol%. The fluidizing agent according to any one of claims 1 to 3, wherein the inorganic compound (B) is an alkali metal carbonate, an alkaline earth metal carbonate, an alkali metal hydroxide or an alkaline earth metal hydroxide. The fluidizing agent according to any one of claims 1 to 4, wherein the content of the inorganic compound (B) is 90 to 2500% by weight based on the weight of the polymer compound (A). A method for producing a soil cement structure, comprising a fluidizing step of fluidizing the soil cement by applying the fluidizing agent for soil cement according to any one of claims 1 to 5 to the soil cement.