KR101816936B1 - Hydraulic cement composition for injection into soil, and method for improvement in soil using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic cement composition for ground injection which is highly resistant to sedimentation when a suspension solution (cement milk) is used, is difficult to release the injection material even under flowing water, and has excellent permeability and durability And a ground improvement method using the same.
[MEANS FOR SOLVING PROBLEMS] Blaine For blast furnace slag fine powder (100 parts) and blast furnace slag fine powder (100 parts) having a specific surface area of 7000 ~ 16000cm2 / g and median diameter of 1 ~ 7㎛, And 5 to 30 parts of a classifying cement which satisfies all of the above requirements, and 0.1 to 3 parts of a polyacrylic acid-based dispersing agent per 100 parts in total of the blast furnace slag fine powder and classifying cement (a melamine- The present invention relates to a hydraulic cement composition for ground penetration.
(1) Classifying cement characterized by containing calcium carbonate in an amount of 6 to 20 parts by weight per 100 parts by weight of cement
(2) Classification cement having a bain specific surface area of 7000 to 16000 cm < 2 > / g
(3) Classification cement having a median diameter of 1 to 7 μm
Further, water-added hydraulic cement composition for ground injection is kneaded and kneaded, and this cement milk is injected into the ground.

Description

Technical Field [0001] The present invention relates to a hydraulic cement composition for ground injection, and a method for improving the soil using the same.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic cement composition for ground penetration and a soil improvement method using the same.

As a kind of soil improvement method, there is a chemical solution injection method for injecting a drug having hardenability into the ground through a rod in order to strengthen a soft ground, and a lot of chemical solution injection materials are known. For example, water-based fillers, special silica fillers, polymeric fillers, and suspension fillers such as cement, clay, and slag. Unlike the method in which the soil is disturbed by a high-pressure jet (jet flow) as in the jet grout method, it is possible to improve the soil without disturbing the ground as much as possible, Because it is characterized by a lot of performance. In the case of a drug solution injection material, there are a solution type and a suspension type, and when a high permeability is required, a solution type may be used. However, the solution-type drug solution injection material has high permeability, but the strength of the obtained cured product itself is small, and the shrinkage of the cured product is large, so that there is a problem in long-term durability. On the other hand, in the case of the suspension-type drug solution injection material, the use of cement or slag, which exhibits hydraulic properties, has the advantage that relatively high strength development can be expected and long-term durability can be easily ensured. Further, in the case of the suspension type, since the liquid is a chemical liquid with particles, when the liquid is suspended, the particles precipitate immediately, and troubles such as clogging of the injection hose may occur during actual use in some cases.

BACKGROUND OF THE INVENTION [0002] As a suspension type chemical liquid injection material, there is known an injection material composition comprising a polycarbonate-based dispersant as an essential component in a cement clinker and a blast furnace slag made into a fine powder (see, for example, Patent Documents 1, 2 and 3). These techniques provide an injection material composition having improved permeability by using a specific polycarboxylic acid-based dispersant. When there is no description about the content ratio of calcium carbonate or calcium carbonate in the cement, and when the filler composition is allowed to stand still There is no description on the anti-settling performance of the anti-settling agent, and there is no example of durability.

On the other hand, as an injection material having a gelation time, an injection material containing water glass, a solidifying agent, and a blast furnace slag having a blaine of 8,000 cm 2 / g or more is known (see, for example, Patent Document 4 , 5, 6).

Patent Document 4 shows that a cured body having a high gel strength is obtained at a water level at a level of several tens of seconds by using fine powder slag in combination, which is an evaluation of only the compressive strength and has a large amount of water glass so that water glass is mainly used. In addition, there is no description (description) about the sedimentation preventing performance or permeability of the particles.

Patent Document 5 discloses a water glass having a molar fraction in the range of 2.8 to 4.0, a particulate slag having an average particle diameter of 10 μm or less and a specific surface area of 5000 cm 2 / g or more, preferably 8000 cm 2 / g or more, If necessary, it is a technique relating to an injection material which further contains cement. In this document, there is a description on the use amount of water glass, the compression strength and the permeability, but there is no description (description) about the sedimentation prevention performance of the particles.

Patent Literature 6 discloses a slag cement which is composed of suspension type grout containing a mixture of fine particle slag and fine particle cement, wherein the slag and cement have an average particle diameter of 10 mu m or less and a specific surface area of 5000 cm2 / g or more, respectively, Is less than or equal to 50%, wherein the suspension type grout further contains water glass and / or an alkali material. In this document, similarly to the document 5, although there is a description on the use amount of water glass and permeability, it is an evaluation of only the compressive strength as the evaluation of the cured product.

In Patent Document 7, there is proposed a method for producing a water-soluble polymer by mixing water, a fine particle water slag, an alkali stimulant, a dispersant, a high molecular substance which is dissolved or dispersed in water to impart viscosity, The present invention relates to a suspension type soil conditioner. Although this document describes permeability and sedimentation preventing performance, there is no disclosure concerning the characteristics of the cured product, and it is impossible to know the reinforcing performance of the cured product when it is injected into the ground and solidified.

Japanese Patent Application Laid-Open No. 2007-238428 Japanese Patent Application Laid-Open No. 2007-238925 Japanese Patent Application Laid-Open No. 2004-175989 Japanese Patent Application Laid-Open No. 02-167848 Japanese Patent Application Laid-Open No. 07-229137 Japanese Patent Application Laid-Open No. 07-286173 Japanese Patent Application Laid-Open No. 2005-344078

The present invention is based on the finding that even if a suspension solution (suspension solution) (cement milk) mixed by kneading is allowed to stand still, the precipitation resistance of the particles is high and the components of the injection material are floated even under flowing water And which is excellent in permeability and durability, and a soil improvement method using the hydraulic cement composition.

In order to solve the above problems, the present invention adopts the means of the present invention 1 to 6 described below.

The present invention 1 is characterized in that 100 parts by mass of a blast furnace slag fine powder having a specific surface area of 7000 to 16000 cm2 / g, a median diameter of 1 to 7 mu m, and 100 parts by mass of a blast furnace slag fine powder satisfy the conditions And a dispersing agent containing 0.1 to 3 parts by mass of a polyacrylic acid-based dispersing agent based on 100 parts by mass of the total of the blast furnace slag fine powder and the classification cement, Wherein the polyacrylic acid-based dispersant is a copolymer containing a monomer of the following general formula (I).

(1) Classifying cement characterized by containing calcium carbonate in an amount of 6 to 20 parts by mass based on 100 parts by mass of classifying cement

(2) Classification cement having a bain specific surface area of 7000 to 16000 cm < 2 > / g

(3) Classification cement having a median diameter of 1 to 7 m
CH ₂ = C (R ¹ ) COO (R ² O) n R ³ (I)
(Wherein R ¹ is a hydrogen atom or a methyl group, R ² O is an oxyalkylene group having 2 to 4 carbon atoms, n is an integer of 5 to 40, and R ³ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms)

The present invention 2 is also the hydraulic cement composition for ground injection according to the first aspect of the invention, wherein the dispersant contains a melamine-based dispersant.

The present invention 3 is a cement milk in which water is added to a hydraulic cement composition for ground injection of the present invention 1 or 2 and kneaded and mixed.

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The present invention 4 is characterized in that the bleeding rate of the cement milk after standing for 60 minutes measured by the method of JSCE-F522 in which the water-soluble cement composition is mixed with water by kneading is 2% or less To be cemented milk according to the third aspect of the present invention.

The present invention 5 is a ground improvement method for injecting the cement milk of the present invention 3 or 4 into a ground.

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The present invention 6 is the ground improvement method of the present invention 5, which is used for ground improvement for the purpose of liquefaction.

Herein, "parts" and "%" in this specification refer to mass parts and mass% unless otherwise specified.

INDUSTRIAL APPLICABILITY The hydraulic cement composition for ground injection of the present invention is excellent in permeability and can exhibit the effect of improving the ground.

The blast furnace slag fine powder to be used in the present invention is produced by pulverizing steel slag generated in the production of pig iron having a blasted surface area of 7000 to 16000 cm 2 / g and a median diameter of 1 to 7 μm. It is used as an admixture for general blast furnace cement and concrete. The blaine specific surface area is a value measured in a blanket air-permeable device of JIS R 5201, and is 7000 to 16000 cm 2 / g.

When the blast furnace slag fine powder is less than 7000 cm2 / g, the bleeding ratio becomes large and sufficient permeability may not be obtained. When the blast furnace slag fine powder is more than 16000 cm2 / g, the manufacturing cost becomes excessive, which is not practical.

The median diameter of the blast furnace slag fine powder is preferably 1 to 7 mu m. For example, the median diameter can be measured by a laser diffraction particle size distribution meter. If the thickness is less than 1 mu m, the manufacturing cost is too high to be practical, and if it exceeds 7 mu m, the bleeding ratio becomes large and the permeability may be deteriorated.

The classifying cement used in the present invention is one in which the particle size of the cement is adjusted using a classification facility. It is preferable that calcium carbonate is contained in an amount of 6 to 20 parts and more preferably 10 to 15 parts in 100 parts of the classification cement.

In the present invention, by containing 6 to 20 parts of calcium carbonate in 100 parts of classifying cement, it has characteristics that are hardly compatible with each other such as sedimentation preventing performance and durability. When the amount is less than 6 parts, sufficient sedimentation preventing performance can not be obtained. When the amount exceeds 20 parts, the viscosity (viscosity) increases and the strength decreases.

Calcium carbonate contained in the classified cement is finely divided by the classification, and therefore, the reactivity is good. Calcium carbonate is usually used as a part of sand when a cement filler or a concrete is produced. Since the powdery calcium carbonate (limestone fine powder) normally used is 4000-6000 cm2 / g, the powder is finer and has higher reaction activity, so that the effect of the strength enhancement can be expected. It reacts with calcium aluminate (3CaO · Al ₂ O ₃ ) contained in cement to produce monocarbonate or hemocarbonate. Gypsum likewise reacts with calcium aluminate (3CaO · Al ₂ O ₃ ) contained in cement to form ettringite. However, when calcium carbonate is present in a specific amount, the reaction of monocarbonate or hemocarbonate is excellent, It is considered that the effect of inhibiting the conversion of leucite to monosulfate is suppressed and the durability is easily ensured.

Classification cement can be used for Portland cement such as ordinary Portland cement, early strength Portland cement, low heat Portland cement, medium heat Portland cement, and sulfated cement. It can be used if it meets the conditions of (1) and (2) in the first aspect of the invention. The same applies to mixed cements such as fly ash cement and silica cement, as well as refractory cements such as alumina cement.

The powdered cement powder is preferably 7000 to 16000 cm2 / g and 9000 to 16000 cm2 / g as with the blast furnace slag fine powder. If it is less than 7000 cm < 2 > / g, the bleeding rate becomes large, and sufficient permeability may not be obtained. When it exceeds 16000 cm &

The median diameter of the classified cement is preferably 1 to 7 mu m. For example, the median diameter can be measured by a laser diffraction particle size analyzer. If the thickness is less than 1 mu m, the manufacturing cost is too high to be practical, and if it exceeds 7 mu m, the bleeding ratio becomes large and the permeability may be deteriorated.

The proportion of the classified cement is 5 to 30 parts, preferably 10 to 25 parts, per 100 parts of the blast furnace slag fine powder. When the amount is less than 5 parts by weight, sufficient strength development may not be obtained. When the amount is more than 30 parts by weight, permeability may be deteriorated.

The dispersant of the present invention contains a polyacrylic acid-based dispersant.

The polyacrylic acid-based dispersant of the present invention exhibits an effect of suppressing the sedimentation of the particles when formed into a suspension solution and an effect of imparting permeability. Is a copolymer containing a monomer represented by the following general formula (I).

CH ₂ = C (R ¹ ) COO (R ² O) n R ³ (I)

In the formula (I), R ¹ represents a hydrogen atom or a methyl group, R ² O represents an oxyalkylene group having 2 to 4 carbon atoms, for example, -CH ₂ CH ₂ O-, -CH ₂ CH ₂ CH ₂ O -, -CH ₂ CH (CH ₃ ) O-, -CH ₂ CH (CH ₂ CH ₃ ) O-, -CH ₂ CH ₂ CH ₂ CH ₂ O- and the like. n represents the number of moles of the oxyalkylene group added and is an integer of 5 to 40, preferably 7 to 35, more preferably 9 to 30. If the addition mole number (n) is too small, the dispersing ability becomes insufficient. On the other hand, if it is too large, it becomes a solid having a high melting point, and handling becomes difficult.

R ³ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, and a butyl group.

Examples of the monomer include polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polybutylene glycol mono (meth) acrylate, methoxypolyethylene glycol (meth) acrylate having an addition mole number of alkylene oxide of 5 to 40 moles Methoxypolyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, methoxypolybutylene glycol (meth) acrylate, ethoxypolyethylene glycol (meth) acrylate, ethoxypolypropylene glycol (Meth) acrylate, propoxypolyethylene glycol (meth) acrylate, and propoxypolyethylene glycol (meth) acrylate. These may be used singly or in combination of two or more. If a monomer represented by the general formula (I) is contained, a copolymer obtained by combining with a monomer component having another chemical structure may be used.

Among these, a copolymer containing methoxypolyethylene glycol (meth) acrylate or methoxypolypropylene glycol (meth) acrylate is preferable in terms of sedimentation preventing ability and penetration performance.

The dispersant of the present invention may contain, in addition to the polyacrylic acid-based dispersant, a melamine-based dispersant.

The melamine-based dispersant of the present invention is a dispersant obtained by, for example, sulfonating melamine with sulfite and formaldehyde, followed by further condensation with formaldehyde. Alkaline metal salts such as sodium and potassium of melamine sulfonic acid formaldehyde condensate, and alkaline earth metal salts such as calcium and magnesium.

The melamine-based dispersant of the present invention is used in combination with a polyacrylic acid-based dispersant. When used in combination, the proportion of the melamine-based dispersant is preferably 10 to 1000 parts, more preferably 30 to 600 parts, per 100 parts of the polycarboxylic acid-based dispersant. If the amount is less than 10 parts, the effect of preventing sedimentation of the particles may not be improved in some cases. If the amount exceeds 1000 parts, the sedimentation preventing performance may be deteriorated.

The effect of reducing the bleeding rate immediately after kneading and mixing is greater than when the polyacrylic acid-based dispersing agent alone is used. Therefore, since the dispersing performance of the particles is improved over a long period of time, permeability to the simulated ground is improved, and the particles showing uniform hydraulic characteristics are dispersed in the ground, so that a stronger and more uniform compacted product can be obtained.

The amount of the dispersant to be used is 0.1 to 3 parts, preferably 0.3 to 2 parts, per 100 parts in total of the blast furnace slag fine powder and the classification cement. If it is less than 0.1 part, sufficient sedimentation preventing performance and permeability can not be obtained, and even if the amount exceeds 3 parts, the effect becomes ineffective.

However, a known cement admixture (material) can be used in combination with the hydraulic cement composition for ground injection of the present invention within a range not adversely affecting the original performance. (AE), an AE water reducing agent, a high performance water reducing agent, a high performance AE water reducing agent, a fluidizing agent, a coagulation retardant, a coercive agent, a defoaming agent, a thickener, a waterproofing agent, an expanding agent, Polymer emulsion for cement admixture, and clay minerals.

The hydraulic cement composition for ground penetration according to the present invention is formed into a milky form by adding water. As the amount of water to be added increases, permeability improves. However, there is a fear that the separation of material is promoted and the material is occluded in the press-feeding hose. If it is less, the viscosity of the cement milk becomes excessively large. The optimum range of the water to be used is preferably from 400 to 1,500 parts, more preferably from 700 to 1,200 parts, per 100 parts in total of the blast furnace slag fine powder, the classification cement and the dispersant. When the amount of water to be used is within the above range, the bleeding rate after 60 minutes of cement milk can be made 2% or less by the method of JSCE F-522 of the Society of Civil Engineering (JSCE F-522). When the bleeding rate exceeds 2%, the feeding of the injection material is stopped for 60 minutes or more, and occasionally occludes when the restarting is performed.

The mixing time of the hydraulic cement composition for ground injection of the present invention with water is not particularly limited, but a predetermined amount of water is added to the grout mixer, the hydraulic cement composition for ground injection according to the present invention is added, Mix for a minute and mix.

The injection site is not particularly limited as long as it is an improvement of a weak ground and can be applied to a ground in which various structures such as a port, a shore, an airport, and the like are located, It can be used for the purpose of waterproofing or waterproofing grout, heaving preventing grout, sinking preventing grout, blowing preventing grout, earth pressure reducing grouting, supporting force increasing grouting, and dust preventing grouting. Since the permeability is good, it can be applied to the ground of sandy soil (including sand) and effectively functions as a countermeasure against liquefaction.

The construction method of the present invention is not particularly limited, and a construction equipment used in ordinary chemical solution injection can be used, and it is possible to comply with the injection design and construction method which are usually performed. For example, there is a method in which a cement milk adjusted by a mixer is pumped through a hose by a pump, and the injection material is injected through a rod disposed in the ground. The rod used at this time is not particularly limited, but a single pipe rod, a single-pipe strainer rod, a double pipe rod, and a double packer type double pipe rod can be used.

Basically, the hydraulic cement composition for ground injection according to the present invention is injected in one shot. However, depending on the condition and purpose of the ground, a commercially available condensation accelerator and various other admixtures are separately fed under pressure so that 1.5 shots or 2 It is also possible to construct by shot method.

Example  One

The hydraulic cement composition for ground injection was adjusted by changing the classification cement to 100 parts of the blast furnace slag powder and adding 1.0 part of the dispersant shown in Table 1 to 100 parts of the blast furnace slag fine powder and the classification cement in total. Water was added to 100 parts of the hydraulic cement composition for ground injection so as to be 850 parts, and the mixture was kneaded with a grout mixer for 2 minutes. The viscosity, bleeding rate, permeability and compressive strength of the obtained cement milk were measured. The results are shown in Table 1.

<Materials Used>

Blast furnace slag fine powder (a): commercially available blast furnace slag fine powder, blast furnace specific surface area 10500 cm 2 / g, median diameter 3.6 탆

Classification cement (e): Classified cement after mixing Portland cement and calcium carbonate in general, Blaine specific surface area 9700 cm2 / g, median diameter 4.1 mu m, calcium carbonate content 11.3%

R ² O represents an oxyethylene group having 2 carbon atoms, R ³ represents an alkylene group having 2 carbon atoms, and R ³ represents an alkylene group having ¹ to 6 carbon atoms. Methyl group.

Dispersant (B): Dispersant (A) was prepared by mixing 300 parts of a melamine-based dispersant (manufactured by Japan Sika Ltd.) with 100 parts of the dispersant

<Measurement method>

Viscosity: Measured using a B-type rotational viscometer. Viscosity was measured immediately after completion of the dough, 3 hours and 6 hours later. The temperature at the time of measurement is 25 ° C.

Bleeding rate: JSCE-F522-1999 The injection rate of prepacked concrete and the rate of expansion of the mortar were tested according to the polyethylene bag method. The measurement was performed after 0.5 hours, 1 hour, and 2 hours. The temperature at the time of measurement is 25 ° C

Permeability: Based on the preparation method of the stabilized soil by injecting the chemical solution as shown in JGS0831-2000. The infiltration condition was observed when a cement milk was injected at a pressure of 0.05 MPa to a simulated ground filled with Toyoura sand in an acrylic pipe having a diameter of 50 mm and a height of 1000 mm and water tight.

Compressive strength: The acrylic pipe subjected to the permeability test was cut to a height of 100 mm, and the sand gel cured from the acrylic pipe was taken out and the compressive strength was measured. The age of measurement is 28 days.

It can be seen from Table 1 that a specific amount of the classification cement is blended with the blast furnace slag fine powder of the present invention and a polyacrylic acid type dispersant is used in combination to produce a filling material cement milk having a small bleeding rate and exhibits excellent permeability, And the compressive strength is also well expressed. In particular, by using the dispersant (B) containing the polyacrylic acid-based dispersant and the melamine-based dispersant, it is found that the bleeding rate is reduced and the strength development is also improved.

Example  2

15 parts of classifying cement having different baine specific surface areas to 100 parts of blast furnace slag fine powder having different surface area of blast, 1.0 part of dispersant (A) to 100 parts of blast furnace slag fine powder and classifying cement in total to prepare hydraulic cement composition for ground injection Respectively. Water was added to 100 parts of the hydraulic cement composition for ground injection so as to be 850 parts, and the mixture was kneaded with a grout mixer for 2 minutes. The viscosity, bleeding rate, permeability and compressive strength of the obtained cement milk were measured. The results are shown in Table 2.

<Materials Used>

Blast furnace slag fine powder (b): Blaine specific surface area 6100 cm &lt; 2 &gt; / g, median diameter 7.4 mu m

Blast furnace slag fine powder (c): Blaine Specific surface area: 8200 cm &lt; 2 &gt; / g, Median diameter:

Blast furnace slag fine powder (d): Blaine Specific surface area: 15500 cm &lt; 2 &gt; / g, Median diameter:

Classification cement (f): Classified cement mixed with Portland cement and calcium carbonate in general, blast specific surface area of 6050 cm 2 / g, median diameter of 8.6 탆, calcium carbonate content of 9.9%

Classification cement (g): Classified cement after mixing Portland cement and calcium carbonate in general, Blaine specific surface area 8300 cm2 / g, median diameter 6.1 占 퐉, calcium carbonate content 9.5%

Classification cement (h): Classified cement mixed with Portland cement and calcium carbonate in general, having a specific surface area of 15800 cm 2 / g, a median diameter of 2.5 탆, a calcium carbonate content of 13.2%

From Table 2, it can be seen that a small blending rate, good permeability and excellent compressive strength are exhibited by using a blast furnace slag fine powder having a median diameter of 7 탆 or less and a classification cement having a blast specific surface area of 7000 cm 2 / g or more. When either or both of the blast furnace slag fine powder and the classified cement have a blast ratio of less than 7000 cm2 / g or a median diameter of more than 7 m, the bleeding rate becomes larger, the permeability becomes worse, .

Example  3

The classification cement having different contents of calcium carbonate was added to 100 parts of the blast furnace slag fine powder (a) as shown in Table 3, 1.0 part of the dispersant (A) was added to 100 parts of the blast furnace slag fine powder and the classification cement in total, The hydraulic cement composition was adjusted. Water was added to 100 parts of the hydraulic cement composition for ground injection so as to be 850 parts, and the mixture was kneaded with a grout mixer for 2 minutes. For comparison, ordinary portland cement not containing calcium carbonate was classified, and then a predetermined amount of calcium carbonate having a blaine specific surface area of 5500 cm &lt; 2 &gt; / g was added and evaluated in the same manner. The viscosity, bleeding rate, permeability and compressive strength of the obtained cement milk were measured. The results are shown in Table 3.

<Materials Used>

Calcium carbonate: Joetsu Mining Co. Ltd., Blaine Specific surface area 5500㎠ / g Commercially available product

It can be seen from Table 3 that when the calcium carbonate is 6 to 20 parts (the range of the present invention) out of 100 parts of the classification cement, the bleeding rate is small and the strength development is also large. On the other hand, when calcium carbonate is less than 6 parts by weight of 100 parts by weight of the cement or when the content of calcium carbonate is within the range of the present invention, when the calcium carbonate is added to the classification cement without classification, the tendency of the bleeding rate to be large and the strength- And the reaction activity is small. Therefore, it is considered that long-term durability is also improved because the particles contain a specific amount of fine calcium carbonate to form a hardened body.

Example  4

15 parts of classifying cement (e), 100 parts of blast furnace slag fine powder and classifying cement in total 100 parts were added to 100 parts of blast furnace slag fine powder (a) as shown in Table 4 to prepare a hydraulic cement composition for ground injection. Water was added to 100 parts of the hydraulic cement composition for ground injection so as to be 850 parts, and the mixture was kneaded with a grout mixer for 2 minutes. The viscosity, bleeding rate, permeability and compressive strength of the obtained cement milk were measured. The results are shown in Table 4.

<Materials Used>

Dispersant (C): Dispersant (A) was prepared by mixing 10 parts of a melamine-based dispersant manufactured by Sika Ltd., Japan with 100 parts of a dispersant

Dispersant (D): Dispersant (A) 100 parts was mixed with 30 parts of a melamine dispersant manufactured by Sika Ltd., Japan

Dispersant (E): Dispersant (A) was prepared by mixing 100 parts of a dispersant (A) with 100 parts of a melamine-

Dispersant (F): Dispersant (A) was prepared by mixing 600 parts of a melamine dispersant manufactured by Sika Ltd., Japan with 100 parts of dispersant

Dispersant (G): Dispersant (A) 100 parts was mixed with 1000 parts of a melamine dispersant manufactured by Sika Ltd., Japan

Dispersant (H): Naphthalenesulfonic acid salt type dispersant DAI-ICHI Cellflow 110P manufactured by SEIYAKU KOGYO Co.,

Dispersant (I): Ligninsulfonic acid salt type dispersant Vanillyx N manufactured by Nippon Paper Industries Co., Ltd.

Dispersant (J): Melamine dispersant Sikament FF manufactured by Sika Ltd., Japan

<Measurement method>

Deviation of Compressive Strength: 10 pieces of a compressive strength specimen were prepared by cutting a hardened sand gel into a length of 100 mm by penetrating into an acrylic pipe of 1000 m, and the coefficient of variation when the compressive strength was measured was obtained.

From Table 4, it can be seen that the bleeding rate can be reduced by using the polyacrylic acid-based dispersant, and good permeability can be ensured. Particularly, it is preferable to use it in combination with a melamine-based dispersing agent, and it is considered that it is possible to obtain a more uniform modified solidified body because the difference in compressive strength due to the difference in penetration distance becomes smaller. When a dispersing agent other than the polyacrylic acid-based dispersing agent (naphthalenesulfonic acid salt-based dispersing agent, ligninsulfonic acid salt-based dispersing agent, or melamine-based dispersing agent) is used alone, good permeability can not be ensured.

Example  5

As shown in Table 5, the hydraulic cement composition for ground injection was adjusted, and water shown in the table was added to 100 parts of the composition to adjust the cement milk. The cement milk was used to perform a penetration test (flow down test), and a cement milk leak test was performed on the assumption of a simulated soil having a water current (water flow). In the evaluation item, the cured product was taken out from the simulated ground after 7 days, with or without the outflow of the cement milk, and the diameter was confirmed when the cured product was hardened in a substantially spherical shape. The test results are shown in Table 6.

<Test Method>

Penetration test: The test was conducted in accordance with the permeability test method of the soil indicated in JGS0311-2000. The test conditions were as follows: No. 5 silica sand was charged in a transparent acrylic container having a diameter of 10 mm × 23 cm to a gap ratio of 40.5% to prepare a simulated ground. However, the bottom surface of the acrylic container used to make the simulated ground was set with a filter to allow water or cement milk to flow out. The pipe was set so that the cement milk was injected near the center of the simulated ground, and the simulated soil container thus prepared was immersed in a water-filled container. The simulated soil container immersed in water was filled with 120 cc of mixed cement milk by mixing water from a piping to make a water level difference of 0.7 cm between the top of the simulated ground container and the water filled container. , And the outflow of cement milk from the simulated soil was observed. The state of the cement mortar cured article immersed in the simulated ground was such that the simulated soil container was dismantled after 7 days at the latest and the cured body was taken out from the inside to check its shape and diameter when it was hardened to a substantially spherical shape. The bleeding rate of the injection material before injection was also measured.

It can be seen from Table 6 that even if the cement composition for ground injection according to the present invention is used for injection into a ground under flowing water, it is held in the ground without flowing out to form a cured body according to the theoretical theory. Further, since the cured product is hardened in the ground in a state of a substantially spherical shape, uniform infiltration is also performed. It is also understood that when the amount of water used is within the range of 400 to 1,500 parts relative to 100 parts of the hydraulic cement composition for ground injection, the change in the bleeding rate is small.

Example  6

In the liquefaction countermeasure construction of the breakwater basement ground, the actual construction using the cement composition for ground injection of the present invention was performed. The construction method is the same as that of Experiment No. 1 with a grout mixer. 5-9, 5-11, 5-16 were adjusted and injected into the ground. Each cement milk was kneaded for 2 minutes, mixed and temporarily transferred to a reservoir tank and pushed and injected through a hose and an injection tube (single tube rod) with a grout pump. The pressure control during injection was 0.5 MPa at maximum, the injection rate was 40%, and the injection amount was 1 m3. All infusion cement milks could be injected below the control of the injection pressure. After one month, the soil was re - digested to check the curing condition of the injected cement milk, and it was observed that the injection material cement milk penetrated into the ground and hardened. Both of the cured products had a spherical shape with a diameter of 45 to 65 cm. A sample was cut from the cured product and the compressive strength was measured. The injected material cured body corresponding to 5-9 was 3.5 N / ㎣, Experimental No. 3, 5-11 was 1.4 N / ㎣, Experimental No. 1. 5-16 was 0.4 N / 은, and it was confirmed that there was a sufficient improvement effect.

Example  7

The cement composition for ground injection of the present invention was kneaded and mixed with the equipment used in the liquefaction countermeasure construction work of the breakwater foundation foundation in Example 6, and the mixture was pushed through the hose, the feeding of the soil was stopped, . Thereafter, the starting state was confirmed when the operation was started again. The formulation thus confirmed was as follows. 5-9, 5-11, 5-13, 5-14, 5-18 (the amount of water mixed by kneading is different). 5-1, 5-2, 5-3, 5-4, and 5-6. As a result, 5-9, 5-11, 5-13, 5-14, and 5-18, there was almost no sedimentation of particles in the hose, and the pressure feeding was resumed smoothly without applying pressure at the time of starting. On the other hand, 5-1, 5-2, 5-3, 5-4, and 5-6, sedimentation of the particles in the hose was confirmed. In particular, 5-4, and 5-5 were covered with sedimented particles of about half of the hose section, and could not be restarted. Experiment No. 5-1, 5-2, and 5-3 were able to start, but massive particles that flowed through the hose at a high starting pressure and did not disperse in the water after starting had flowed through the hose, I have.

INDUSTRIAL APPLICABILITY The hydraulic cement composition for ground injection of the present invention is small in material separation and excellent in permeability, and can be rapidly improved in workability and in a wide range. Further, the cured product formed by the classifying cement, the fine-particle slag and the dispersant having the characteristics exhibits sufficient strength and is excellent in long-term durability, so that it can be applied to reinforcement work of various soft grounds such as countermeasures against liquefaction of sandy soil.

Claims (7)

Blaine For 100 parts by weight of blast furnace slag fine powder having a specific surface area of 7000 to 16000 cm2 / g and median diameter of 1 to 7 占 퐉 and 100 parts by weight of blast furnace slag fine powder, And 5 to 30 parts by mass of a classifying cement which satisfies all of the conditions of 100 parts by mass of the blast furnace slag fine powder and the classification cement and 0.1 to 3 parts by mass of a polyacrylic acid- , And the polyacrylic acid-based dispersant is a copolymer containing a monomer of the following general formula (I).
(1) Classifying cement characterized by containing calcium carbonate in an amount of 6 to 20 parts by mass based on 100 parts by mass of classifying cement
(2) Classification cement having a bain specific surface area of 7000 to 16000 cm &lt; 2 &gt; / g
(3) Classification cement having a median diameter of 1 to 7 m
CH ₂ = C (R ¹ ) COO (R ² O) n R ³ (I)
(Wherein R ¹ is a hydrogen atom or a methyl group, R ² O is an oxyalkylene group having 2 to 4 carbon atoms, n is an integer of 5 to 40, and R ³ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms) The method according to claim 1,
Wherein the dispersant further comprises a melamine-based dispersant. A cement milk characterized in that water is added to the hydraulic cement composition for ground penetration as set forth in claim 1 or 2 and kneaded and mixed. The method of claim 3,
Characterized in that the bleeding rate of cement milk measured by the method of JSCE-F522 after standing for 60 minutes is 2% or less when water is added to the hydraulic cement composition for ground injection and kneaded and mixed. Cement milk. A ground improvement method in which the cement milk according to claim 3 is injected into a ground. The method of claim 5,
A method for improving a soil structure characterized by using the soil improvement method for the purpose of liquefaction. delete