JP2009035453A - Method for fluidizing soil cement slurry - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for fluidizing a soil cement slurry which is capable of imparting enough fluidity and fluidity maintaining property to the soil cement, and, at the same time, capable of imparting enough water-stopping property, strength, and the like, to the resulting hardened soil cement, through suppressing foaming property and promoting uniform mixing of a cement milk and a soil. <P>SOLUTION: The method for fluidizing a soil cement slurry comprises mixing a cement milk with a fluidizing agent comprising a component A which is a water-soluble vinyl copolymer formed by alkali-hydrolyzing a copolymer of isobutylene and maleic anhydride and has a mass-average molecular weight of 2,000-50,000, a component B which is one or more selected from the group consisting of saccharides, oxycarboxylic acids and salts of oxycarboxylic acids, a component C which is a specific aliphatic polyether, and a component D which is a specific polyether-based defoaming agent, and containing 50-95 mass% of the component A, 2-35 mass% of the component B, 0.1-20 mass% of the component C and 0.01-5 mass% of the component D, in a mixing ratio of 0.5-25 kg of the fluidizing agent per 1 m<SP>3</SP>of soil. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for fluidizing a soil cement slurry. In mountain construction, underground water construction, soft ground improvement work, etc., a soil cement wall construction method in which cement milk and in-situ soil are mixed and hardened at construction sites is widely used. In this construction method, 1) The amount of construction sludge that will be discarded at a lower rate of cement milk injection into the ground while ensuring the insertability of the stress bearing material (H steel) within a certain working time. In order to suppress, the soil cement slurry mixed with cement milk and soil should have sufficient fluidity and fluid retention. 2) Soil foaming can be suppressed, and uniform mixing of cement milk and soil can be promoted. It is required that the cement wall exhibit sufficient water stoppage and strength. The present invention relates to a method for fluidizing a soil cement slurry that meets such requirements.

  Conventionally, a method using various fluidizing agents is known as a fluidizing method for soil cement slurry (see, for example, Patent Documents 1 to 3). However, these conventional methods have a problem that they cannot sufficiently meet the above-described requirements in the soil cement wall method.

JP 2002-3843 A JP 2002-114550 A JP 2006-298726 A

  The problem to be solved by the present invention can be obtained by allowing the soil cement slurry to have sufficient fluidity and fluid retention, and by suppressing foaming and promoting uniform mixing of cement milk and soil. The present invention provides a fluidizing method of a soil cement slurry that can exhibit sufficient water-stopping and strength and the like in the cured soil cement.

  As a result of researches to solve the above-mentioned problems, the inventors of the present invention correctly use a method in which a specific four-component fluidizing agent is used in cement milk so as to have a predetermined ratio with respect to soil. I found out.

That is, this invention consists of the following A component, B component, C component, and D component, this A component is 50-95 mass%, this B component is 2-35 mass%, and this C component is 0.1-20. A fluidizing agent containing 0.01% to 5% by mass of the D component and 0.01% to 5% by mass of D component is used by being added to cement milk so as to have a ratio of 0.5 to 25 kg per 1 m ^{3 of} soil. The present invention relates to a fluidizing method for soil cement slurry.

  Component A: Water-soluble vinyl copolymer having a weight average molecular weight of 2000 to 50000 obtained by alkaline hydrolysis of a copolymer of isobutylene and maleic anhydride

  Component B: one or more selected from sugars, oxycarboxylic acids and oxycarboxylic acid salts

Component C: Aliphatic polyether represented by the following chemical formula 1

  Component D: polyether-based antifoaming agent represented by the following chemical formula 2

In Chemical Formula 1 and Chemical Formula 2,
R ¹ : Aliphatic hydrocarbon group having 8 to 20 carbon atoms R ² : Aliphatic hydrocarbon group having 12 to 20 carbon atoms A ¹ : Polyoxyethylene group composed of 2 to 20 oxyethylene units in the molecule Residue obtained by removing all hydroxyl groups from polyethylene glycol having A ² : Consists of a total of 23 to 70 oxyethylene units and oxypropylene units in the molecule, and the oxyethylene units and the oxypropylene units are in a block form Residues obtained by removing all hydroxyl groups from polyalkylene glycol having a polyoxyalkylene group attached to

In the fluidizing method of soil cement slurry according to the present invention (hereinafter simply referred to as fluidizing method of the present invention), when cement milk and soil are mixed to form a soil cement slurry, the cement milk contains a fluidizing agent. Use it. Examples of the cement used in the cement milk include ordinary Portland cement, blast furnace cement, fly ash cement, and the like, among which blast furnace cement B type is preferable. When cement milk and soil are mixed to form a soil cement slurry, the amount of cement used is usually 100 to 500 kg per 1 m ^{3 of} soil, but preferably 150 to 400 kg. When preparing cement milk, it is preferable to use bentonite in addition to cement for the purpose of preventing separation of cement milk and preventing water dissipation of soil cement slurry. When bentonite is used, the amount used is usually 1 to 50 kg per 1 m ^{3 of} soil, preferably 3 to 30 kg. The water / cement ratio of the cement milk varies depending on the properties of the soil mixed therewith, and is usually 100 to 350%, preferably 155 to 330%.

  In the fluidizing method of the present invention, the fluidizing agent used in cement milk as described above is composed of an A component, a B component, a C component, and a D component. Component A is a water-soluble vinyl copolymer having a mass average molecular weight of 2,000 to 50,000 obtained by alkaline hydrolysis of a copolymer of isobutylene and maleic anhydride. Here, the mass average molecular weight means a pullulan-converted mass average molecular weight measured by gel permeation chromatography (hereinafter simply referred to as GPC method).

Copolymerization of isobutylene and maleic anhydride and alkali hydrolysis of the resulting copolymer can be performed by known methods. For example, ethylbenzene, maleic anhydride, a radical chain transfer agent and a radical initiator are charged in an autoclave as a solvent, and the reaction system is purged with nitrogen. Then, isobutylene is injected, and the pressure is 2 to 5 kg / cm ² at 60 to 120 ° C. A method of radical polymerization under conditions for 2 to 10 hours to obtain a copolymer as a precipitate and then hydrolyzing the copolymer with an aqueous alkaline solution can be mentioned.

  In order to obtain a desired copolymer, the type and amount of radical initiator and radical chain transfer agent, the type and amount of solvent, polymerization temperature, polymerization time and the like are appropriately selected. Examples of the radical initiator used here include azo initiators such as azobisisobutyronitrile and 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), benzoyl peroxide, lauroyl peroxide, Non-aqueous initiators such as cumene hydroperoxide are listed.

In the copolymer of isobutylene and maleic anhydride, the copolymerization ratio of both is
It is preferable that isobutylene / maleic anhydride = 45/55 to 55/45 (molar ratio), and it is more preferable that the ratio be as close to 50/50 (molar ratio) as possible.

  The alkali used in the alkali hydrolysis of the copolymer of isobutylene and maleic anhydride is preferably an alkali metal hydroxide such as sodium hydroxide, potassium hydroxide or lithium hydroxide, and is inexpensive from an industrial standpoint. An aqueous solution of sodium is more preferred. Alkaline hydrolysis may be a case where a partially neutralized product is obtained as a result or a completely neutralized product is obtained.

  The component A is a water-soluble vinyl copolymer having a mass average molecular weight of 2000 to 50000 obtained by alkaline hydrolysis of a copolymer of isobutylene and maleic anhydride, and the water-soluble copolymer having a mass average molecular weight of 5000 to 35000 It is preferable to do this.

  The B component is one or more selected from saccharides, oxycarboxylic acids, and salts of oxycarboxylic acids. Examples of the saccharide include sucrose, glucose, fructose, galactose, oligosaccharide, and molasses. Examples of the oxycarboxylic acid include gluconic acid and citric acid. Examples of the oxycarboxylic acid salt include glucone. Examples thereof include sodium acid and sodium citrate. Among these, sucrose is preferable as the B component from the viewpoint of dissolution stability with the A component and anti-corrosion properties.

Component C is an aliphatic polyether represented by Chemical Formula 1. As R ^{1 in} Chemical Formula 1, 1) octyl group, nonyl group, decyl group, undecyl group, lauryl group (dodecyl group), tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group 8) a saturated aliphatic hydrocarbon group having 8 to 20 carbon atoms such as an eicosyl group, and 2) an unsaturated fat having 8 to 20 carbon atoms such as an 11-dodecenyl group, an 8-hexadecenyl group, a 9-octadecenyl group, and an 11-eicocenyl group. Among them, a saturated hydrocarbon group having 10 to 20 carbon atoms is preferable, a saturated aliphatic hydrocarbon group having 12 to 16 carbon atoms is more preferable, and a lauryl group is particularly preferable.

A ^{1 in} Chemical Formula ¹ is a residue obtained by removing all hydroxyl groups from polyethylene glycol having a polyoxyethylene group composed of 2 to 20 oxyethylene units in the molecule. A residue obtained by removing all hydroxyl groups from a polyethylene glycol having a polyoxyethylene group composed of 12 oxyethylene units is preferred. The C component composed of the aliphatic polyether represented by Chemical Formula 1 described above acts as a surface tension reducing agent for imparting wettability and permeability to clay lump particles in soil, and is mainly a dispersant for soil particles. This promotes the kneading performance of the A component and B component described above.

Component D is a polyether antifoaming agent represented by Chemical Formula 2. As R ^{2 in} Chemical Formula ² , 1) saturation of 12 to 20 carbon atoms such as lauryl group (dodecyl group), tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, etc. Examples include aliphatic hydrocarbon groups, 2) 11-dodecenyl groups, 8-hexadecenyl groups, 9-octadecenyl groups, 11-eicocenyl groups and the like, and unsaturated aliphatic hydrocarbon groups having 12 to 20 carbon atoms. An unsaturated aliphatic hydrocarbon group having 12 to 20 carbon atoms is preferred, and a 9-octadecenyl group is more preferred.

A ^{2 in} Chemical Formula ² is a polyalkylene glycol having a polyoxyalkylene group composed of oxyethylene units and oxypropylene units in the molecule and having the oxyethylene units and the oxypropylene units added in the form of blocks. A residue excluding all hydroxyl groups. Although repetition number of oxyethylene units and oxypropylene units constituting the polyoxyalkylene group A ² is a 23 to 70 in total, preferably with 25 to 60. The polyether antifoaming agent represented by Chemical Formula 2 described above is known in which ethylene oxide and propylene oxide are added in a block form at a ratio of 23 to 70 mol in total with respect to 1 mol of an aliphatic alcohol having 12 to 20 carbon atoms. It can be synthesized by this method.

  In the fluidizing method of the present invention, the fluidizing agent used in cement milk is composed of the A component, B component, C component and D component described above. The content ratio of A component, B component, C component and D component is 50 to 95% by mass of A component, 2 to 35% by mass of B component, 0.1 to 20% by mass of C component, and 0.01 to 5% by mass of D component. % (Total 100 mass%), A component 60-90 mass%, B component 9-30 mass%, C component 0.5-17 mass%, D component 0.1-3 mass% (total 100 mass) %). The content ratio of the A component, B component, C component and D component in the fluidizing agent is related to the properties of the soil mixed with the cement milk containing it within the range of the content ratio as described above. It is preferable to select appropriately.

  The fluidizing agent described above exhibits more excellent effects when the aqueous solution is in the alkaline region. Accordingly, the fluidizing agent preferably has a pH of an aqueous solution having a solid content concentration of 1 mass% within the range of 7.0 to 11, more preferably 7.5 to 10.5. The pH of the fluidizing agent can be adjusted using, for example, an alkali metal hydroxide.

  The fluidizing agent preferably has a surface tension at 20 ° C. of an aqueous solution having a solid content concentration of 1% by mass of 40 mN / m or less, more preferably 25 to 40 mN / m. The surface tension of the fluidizing agent can be adjusted, for example, by adjusting the content ratio of the C component.

In the fluidizing method of the present invention, cement milk that contains a fluidizing agent in advance is prepared, and the cement milk and soil are mixed to form a soil cement slurry. In this case, the amount of the fluidizing agent used is 0.5 to 25 kg per 1 m ^{3 of} soil, but preferably 1 to 10 kg.

  In the fluidizing agent method of the present invention, when the fluidizing agent is used, other agents can be used in combination for the purpose. Examples of such other agents include antiseptics, setting accelerators, waterproofing agents and the like. Although the fluidization method of the present invention has been described above, the fluidization method of the present invention is effective when applied to a soil cement wall construction method in which cement milk and in-situ soil are stirred and mixed and hardened at a construction site. Is expensive.

  According to the fluidization method of the present invention, the soil cement slurry can be provided with sufficient fluidity and fluid retention, and at the same time, the foaming property is suppressed and uniform mixing of cement milk and soil is promoted. Sufficient water-stopping and strength can be expressed in the cured soil cement. These effects are exhibited even when the soil is viscous and contains a large amount of clay and silt.

  Hereinafter, in order to make the configuration and effects of the present invention more specific, examples and the like will be described. However, the present invention is not limited to the examples. In the following examples and the like, unless otherwise indicated,% means mass%, and part means mass part.

Test Category 1 (Synthesis of water-soluble vinyl copolymer as component A)
Synthesis of water-soluble vinyl copolymer (a-1) 49 g of maleic anhydride, 300 g of ethylbenzene as a solvent, 0.3 g of 3-mercaptopropionic acid as a molecular weight regulator and 1 g of azobisisobutyronitrile as a polymerization initiator The solution was uniformly dissolved with stirring, and the atmosphere was replaced with nitrogen. Next, after 28 g of isobutylene was injected, the temperature of the reaction system was heated to 85 ° C., and the radical polymerization reaction was continued for 6 hours while maintaining the temperature at 85 ° C. to complete the reaction. After completion of the reaction, the temperature of the reaction system was cooled to room temperature. After deaeration, stirring was stopped and the precipitated copolymer was taken out and filtered and dried to obtain 75 g of a pale yellow powdery copolymer. When the copolymer was analyzed, it was copolymerized at a ratio of maleic anhydride / isobutylene = 50/50 (molar ratio). 50 g of this copolymer, 51 g of a 30% aqueous sodium hydroxide solution and 102 g of tap water are placed in a flask equipped with a stirrer and a cooling condenser, heated while stirring, and the copolymer is alkali-hydrolyzed water-soluble vinyl copolymer. A 30% aqueous solution of the polymer (a-1) was obtained. When the molecular weight of this water-soluble vinyl copolymer was measured by GPC, the mass average molecular weight was 20100 (in pullulan conversion).

-Synthesis of water-soluble vinyl copolymer (a-2), (a-3), (ar-1) and (ar-2) In the same manner as the synthesis of water-soluble vinyl copolymer (a-1), Water-soluble vinyl copolymers (a-2), (a-3), (ar-1) and (ar-2) were synthesized. The contents of each water-soluble vinyl copolymer synthesized above are shown in Table 1.

Test Category 2 (Preparation of fluidizing agent)
-Preparation of fluidizing agent (P-1) 250 parts of a 30% aqueous solution of a water-soluble vinyl copolymer (a-1) synthesized in Test Category 1 as the A component, and 30 parts of sucrose (b-1) as the B component 63 parts of aqueous solution, polyoxyethylene as component C (repeating 6 oxyethylene units, hereinafter abbreviated as 6 moles), 17 parts of 30% aqueous solution of lauryl monoether (c-1) and polyether component as D component A 30% aqueous solution of a fluidizing agent (P-1) was prepared by mixing 3 parts of a 30% aqueous suspension of foaming agent (d-1). It was 9.9 and 29.9 mN / m when pH of the solid content concentration 1% aqueous solution of fluidizing agent (P-1) and the surface tension at the temperature of 20 degreeC were measured.

-Preparation of fluidizing agents (P-2) to (P-13) and (R-1) to (R-12) In the same manner as the preparation of fluidizing agents (P-1), fluidizing agents (P- 2) to (P-13) and (R-1) to (R-12) were prepared. The contents of each fluidizing agent prepared above are summarized in Table 2.

In Table 2,
* 1: pH of aqueous solution with 1% solid content
* 2: Surface tension of an aqueous solution with a solid content of 1% at 20 ° C. a-1 to a-3, ar-1 and ar-2: water-soluble vinyl polymers synthesized in Test Category 1 ar-3: formaldehyde naphthalene sulfonate Condensate b-1: Sucrose b-2: Glucose b-3: Sodium gluconate b-4: Gluconic acid c-1: Polyoxyethylene (6 mol) monolauryl ether (HLB number 11.7)
c-2: polyoxyethylene (9 mol) monocetyl ether (HLB number 12.4)
c-3: polyoxyethylene (15 mol) monooleyl ether (HLB number 14.2)
d-1: α-octadecenyl-ω-hydroxy-polyoxyethylene (6 mol) polyoxypropylene (32 mol)
d-2: α-octadecenyl-ω-hydroxy-polyoxyethylene (9 mol) polyoxypropylene (48 mol)
d-3: α-lauryl-ω-hydroxy-polyoxyethylene (3 mol) polyoxypropylene (32 mol)

Test category 3 (Preparation of soil cement slurry)
Comparative example 1
Blast furnace cement type B (density = 3.04 g / cm ³ ) 202 g, water 650 g and bentonite 14 g were placed in a Hobart mixer and mixed uniformly to prepare cement milk. To this cement milk, 1690 g (equivalent to 0.001 m ³ ) of excavated soil mainly composed of silty clay listed in Table 3 was added and mixed. A soil cement slurry corresponding to 1 was prepared. The prepared soil cement slurry has a flow value of 212 mm immediately after the physical property evaluation in Test Category 4 and has a fluidity that allows H steel to be inserted at the construction site without adding a fluidizing agent immediately after preparation. It was a cement slurry.

-Examples 1-16 and Comparative Examples 2-14
199 g of blast furnace cement type B (density = 3.04 g / cm ³ ), 419 g of water, 16 g of bentonite and a quantity of fluidizing agent as shown in Table 5 are put in a Hobart mixer and mixed uniformly. Prepared. To this cement milk, 1690 g of excavated soil having physical property values listed in Table 3 was added and mixed. A soil cement slurry corresponding to 2 was prepared.

Examples 17 to 29 and comparative examples 15 to 25
Blast furnace cement type B (density = 3.04 g / cm ³ ) 190 g, water 296 g, bentonite 17 g and the amount of fluidizing agent used in Table 6 are put in a Hobart mixer and mixed uniformly. Prepared. To this cement milk, 1690 g of excavated soil having physical property values described in Table 4 was added and mixed. A soil cement slurry corresponding to 3 was prepared.

Examples 30 to 42 and comparative examples 26 to 37
190 g of blast furnace cement type B (density = 3.04 g / cm ³ ), 296 g of water and an amount of fluidizing agent as shown in Table 6 were mixed in a Hobart mixer to prepare a cement milk. To this cement milk, 1690 g of excavated soil having physical property values listed in Table 3 was added and mixed. A soil cement slurry corresponding to 4 was prepared.

Test Category 4 (Evaluation of prepared soil cement slurry)
For the soil cement slurry of each example prepared in Test Category 3, the flow value, flow residual ratio, and air amount were determined as follows, and the results are summarized in Tables 5 to 7. Moreover, about the hardening body obtained from the soil cement slurry of each example, the water permeability ratio and the uniaxial compressive strength were calculated | required as follows, and the result was put together in Table 5-Table 7, and was shown.

  -Flow value: According to JIS-R5201, a flow test was performed immediately after kneading and after 180 minutes, and the flow value (mm) after 15 drops was measured.

  -Flow residual ratio: It calculated | required in (flow value after 180 minutes leaving / flow value immediately after mixing) x100.

  -Air amount: It calculated | required based on JIS-A1171.

-Permeability ratio: In accordance with JIS-A1404, after filling a metal mold having a diameter of 150 mm and a height of 40 mm with a soil cement slurry, the surface is covered with a polyethylene film, and the temperature is controlled at 20 ° C and humidity of 80%. The specimen was cured for 28 days, and after removing the mold, the surface was smoothed to prepare a test specimen. A rubber gasket of 1 cm thickness having a 5 cm diameter circular hole was applied to the center of the upper and lower surfaces of this test body, and after tightening uniformly, a water pressure test of 9.8 kPa from the upper surface was performed for 1 hour. As a measure of water permeability, the following water permeability ratio was calculated. Here, the smaller the numerical value of the water permeability ratio, the better the water shielding property.
Permeability ratio = water permeability (g) of the specimen prepared from the soil cement slurry of each example / water permeability (g) of the specimen prepared from the soil cement slurry of Comparative Example 1

-Uniaxial compressive strength test: Based on JIS-A1108, the compressive strength (N / mm < ² >) of material age 28 days was measured about the molded product shape | molded using the mold of diameter 50mm x height 100mm. In this test, the target value in the soil cement wall method was set to a strength range of 0.2 to 2.0 N / mm ² .

In Tables 5 to 7,
* 3: in terms of solid content of the fluidizing agent used per soil 1 m ³ (kg)
* 4: Uniaxial compressive strength at age 28 days R-13: Sodium polyacrylate (mass average molecular weight 12000)

Claims (9)

It consists of the following A component, B component, C component and D component, the A component is 50 to 95% by mass, the B component is 2 to 35% by mass, the C component is 0.1 to 20% by mass and the D Flow of soil cement slurry characterized by using a cementizing milk containing a fluidizing agent containing 0.01 to 5% by mass of ingredients so as to have a ratio of 0.5 to 25 kg per 1 m ^{3 of} soil. Method.
Component A: Water-soluble vinyl copolymer having a weight average molecular weight of 2000 to 50000 obtained by alkali hydrolysis of a copolymer of isobutylene and maleic anhydride Component B: One selected from saccharides, oxycarboxylic acids and oxycarboxylic acid salts Or two or more C component: The aliphatic polyether shown by following Chemical formula 1

Component D: polyether-based antifoaming agent represented by the following chemical formula 2

(In Chemical Formula 1 and Chemical Formula 2,
R ¹ : Aliphatic hydrocarbon group having 8 to 20 carbon atoms R ² : Aliphatic hydrocarbon group having 12 to 20 carbon atoms A ¹ : Polyoxyethylene group composed of 2 to 20 oxyethylene units in the molecule Residue obtained by removing all hydroxyl groups from polyethylene glycol having A ² : Consists of a total of 23 to 70 oxyethylene units and oxypropylene units in the molecule, and the oxyethylene units and the oxypropylene units are in a block form A residue obtained by removing all hydroxyl groups from polyalkylene glycol having a polyoxyalkylene group attached to   The fluidizing agent comprises 60 to 90% by mass of component A, 9 to 30% by mass of component B, 0.5 to 17% by mass of component C and 0.1 to 3% by mass of component D. A method for fluidizing a soil cement slurry according to claim 1.   The method for fluidizing a soil cement slurry according to claim 1 or 2, wherein the component A is a water-soluble vinyl copolymer having a mass average molecular weight of 5000 to 35000 obtained by alkaline hydrolysis of a copolymer of isobutylene and maleic anhydride.   The method for fluidizing a soil cement slurry according to any one of claims 1 to 3, wherein the component B is sucrose. Component C is a residue obtained by removing all hydroxyl groups from polyethylene glycol having R ^{1 in} Chemical Formula ¹ having a lauryl group and A ¹ having a polyoxyethylene group composed of 4 to 12 oxyethylene units in the molecule. The method for fluidizing a soil cement slurry according to any one of claims 1 to 4, wherein the fluidizing method is used in some cases.   The fluidizing agent is one in which the pH of an aqueous solution having a solid content concentration of 1% by mass is in the range of 7.0 to 11, and the surface tension of the aqueous solution at 20 ° C is 40 mN / m or less. The fluidizing method of the soil cement slurry according to any one of the above.   The method for fluidizing a soil cement slurry according to any one of claims 1 to 6, wherein the cement milk uses blast furnace cement type B as cement.   The method for fluidizing a soil cement slurry according to any one of claims 1 to 7, wherein bentonite is further used in cement milk.   The fluidization method of the soil cement slurry as described in any one of Claims 1-8 used for a soil cement wall construction method.