KR20120109472A - Hydraulic cement composition for injection into soil, and method for improvement in soil using same - Google Patents

Abstract

[Problem] Hydraulic cement composition for ground injection, which has high sedimentation resistance when suspended solution (cement milk), hardly drifts off the injected material even under running water, and has excellent permeability and durability. And it provides a ground improvement method using the same.
[Solution] For 100 parts of blast furnace slag fine powder and 100 parts of blast furnace slag fine powder having Blaine specific surface area of 7000 ~ 16000cm2 / g, median diameter 1 ~ 7㎛, shipbuilding of ⑴ from below 5-30 parts of classification cement which satisfies all the above, and a dispersing agent (melamine-based dispersant) containing 0.1 to 3 parts of polyacrylic acid dispersant based on 100 parts of the blast furnace slag fine powder and the classification cement in total. Hydraulic cement composition for ground injection.
분 a classification cement comprising 6 to 20 parts of calcium carbonate in 100 parts of the classification cement
분 classification cement, characterized in that the specific surface area of blast is 7000 ~ 16000㎠ / g
분 classification cement, characterized in that the median diameter is 1 ~ 7㎛
In addition, it is a cement milk kneaded by adding water to the hydraulic cement composition for ground injection, and the cement milk is injected into the ground.

Description

Hydraulic cement composition for injection into soil, and method for improvement in soil using same}

The present invention relates to a hydraulic cement composition for ground injection and a ground improvement method using the same.

As a ground improvement method, there is a chemical liquid injection method for injecting a drug having a hardenable property into the ground through a rod in order to strengthen the soft ground, and many chemical liquid injection materials are known. For example, water glass injection material, special silica injection material, polymer injection material, and suspension type injection materials, such as cement, clay, slag, etc. are mentioned. In the chemical liquid injection method using the chemical liquid injection material, unlike the method of improving the ground while disturbing the ground by a high-pressure classification such as the jet grouting method, it can be improved without disturbing the ground as much as possible, the equipment is compact It is characterized by a lot of results. The chemical liquid injection material has a solution type and a suspension type, and when high permeability is required, a solution type may be used. However, although the solution type chemical | medical agent injection material has high permeability, since the intensity | strength of the hardened | cured body itself obtained is small, and shrinkage | contraction of hardened | cured material is large, the problem of long-term durability may arise. On the other hand, the suspension-type chemical liquid injection material, which contains hydraulic cement, slag, and the like as a component can be expected to exhibit relatively high strength and easily secure long-term durability, but has a problem of low permeability. In the case of the suspension type, since it is a chemical liquid with particles, the particles settle immediately upon standing, and problems such as blockage in the injection hose may occur during actual construction.

As a suspension type chemical liquid injection material, the injection material composition which makes a fine powdered cement clinker and a blast furnace slag a polycarboxylic acid type dispersant an essential component is known (for example, refer patent document 1, 2, 3). These techniques provide an injection material composition with improved permeability by using a specific polycarboxylic acid-based dispersant, but there is no description of the content ratio of calcium carbonate and calcium carbonate in cement, and when the injection material composition is settled. There is no description of the anti-sedimentation performance of, and there is no embodiment regarding durability.

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

Although patent document 4 shows that the hardened | cured material with high gel strength is obtained at a moisture level in several tens of seconds by using finely divided slag together, it is evaluation only of compressive strength, and there are many compounding quantities of water glass, and water glass is a main body. Moreover, there is no description regarding the sedimentation prevention performance and permeability of a particle | grain.

Patent document 5 is a water glass having a mole fraction of 2.8 ~ 4.0, fine particle slag having an average particle diameter of 10㎛ or less and a specific surface area of 5000 cm 2 / g or more, preferably 8000 cm 2 / g or more, It is a technique regarding the injection material which further contained cement as needed. In this document, although the amount of water glass used is large and there is a description regarding compressive strength and permeability, there is no description regarding the sedimentation prevention performance of particles.

Patent document 6 consists of a suspension type grout containing a mixture of fine particle slag and fine particle cement, and the average particle diameter of these slag and cement is 10 micrometers or less, respectively, specific surface area is 5000 cm <2> / g or more, and the cement mixing ratio It is 50% or less, It is the technique characterized by further containing water glass and / or alkali material in the said suspension grout. Also in this document, as in Document 5, although the amount of water glass used is large and there is a description regarding the permeability, it is only an evaluation of the compressive strength as an evaluation of the cured product.

In addition, Patent Document 7 contains water, fine particle chain slag, alkali stimulant, dispersant, a polymer material dissolved or dispersed in water to impart viscosity, and, if necessary, a solidity improving agent. The technique regarding suspension type ground improvement material characterized by the above-mentioned is shown. In this document, although there is a description regarding the permeability and the sedimentation prevention performance, there is no disclosure regarding the properties of the cured product, and the reinforcing performance when the material is injected into the ground and solidified is unknown.

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

The present invention has high sedimentation resistance of the particles even when the suspension solution (cement milk) mixed with the dough is left still, and the component of the injection material is allowed to float even under running water. An object of the present invention is to provide a hydraulic cement composition for ground injection, which is difficult and excellent in permeability and durability, and a ground improvement method using the same.

MEANS TO SOLVE THE PROBLEM This invention employ | adopts the means of this invention 1-7 described below in order to solve said subject.

In the present invention 1, 100 parts of blast furnace slag fine powder having a Blaine specific surface area of 7000-16000 cm2 / g and a median diameter of 1-7 μm, and 100 parts of blast furnace slag fine powder, all of the following conditions under 5-30 parts of classification cement to be satisfied and a dispersing agent containing 0.1-3 parts of polyacrylic acid-based dispersant based on 100 parts of the blast furnace slag fine powder and the classification cement in total. It is a hydraulic cement composition.

분 a classification cement comprising 6 to 20 parts of calcium carbonate in 100 parts of the classification cement

분 classification cement, characterized in that the specific surface area of blast is 7000-16000cm2 / g

분 classification cement, characterized in that the median diameter is 1 ~ 7㎛

This invention 2 is the hydraulic cement composition for ground injection of this invention 1 characterized by the above-mentioned dispersing agent containing a melamine type dispersing agent.

In the present invention 3, the above-mentioned polyacrylic acid-based dispersant is a copolymer containing the monomer of the following general formula (I). Cement composition.

CH ₂ = C (R ¹ ) COO (R ² O) nR ³ (I)

(Wherein R ¹ represents a hydrogen atom or a methyl group, R ² O represents an oxyalkylene group having 2 to 4 carbon atoms, n represents an integer of 5 to 40, and R ³ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms)

The present invention 4 is a cement milk characterized by kneading by adding water to the hydraulic cement composition for ground injection according to any one of the present invention 1-3.

The present invention 5 is the cement milk according to the present invention (4), characterized in that the bleeding rate of the cement milk mixed by kneading by adding water to the hydraulic cement composition exhibits a bleeding rate of 2% or less. .

This invention 6 is a ground improvement method which injects the cement milk of this invention 4 or 5 in the soil.

This invention 7 is the soil improvement method of this invention 6 characterized by using for soil improvement for the purpose of countermeasure of liquefaction.

Here, the part and% in this specification mean a mass part and mass%, unless it mentions specially.

The hydraulic cement composition for ground injection of the present invention is excellent in permeability and can exhibit effects such as ground improvement.

The blast furnace slag fine powder used in this invention is 7000-16000 cm <2> / g in a plain specific surface area, and is 1-7 micrometers in median diameter, and is manufactured by grinding the steel slag which arises when pig iron is manufactured. It is used as a general blast furnace cement and concrete admixture. Blaine specific surface area is the value measured by the Blaine air permeation apparatus of JIS R 5201, and is 7000-16000cm <2> / g.

If the blast furnace slag fine powder is less than 7000 cm 2 / g, the bleeding ratio may be large, and sufficient permeability may not be obtained. If the blast furnace slag fine powder exceeds 16000 cm 2 / g, the manufacturing cost is excessive and not practical.

As for the median diameter of blast furnace slag fine powder, 1-7 micrometers is preferable. For example, the median diameter can be measured by a laser diffraction particle size distribution analyzer. If it is less than 1 micrometer, manufacturing cost will become excessive and it is not practical, and if it exceeds 7 micrometers, a bleeding ratio will become large and there exists a possibility of impairing permeability.

The classification cement used in the present invention is a particle size adjusted cement using a classification facility. It is preferable to contain 6-20 parts of calcium carbonate among 100 parts of classification cements, and to contain 10-15 parts.

The present invention is characterized by containing 6 to 20 parts of calcium carbonate in 100 parts of the classification cement, which has characteristics that are difficult to achieve at first glance, such as sedimentation preventing performance and durability. If it is less than 6 parts, sufficient sedimentation prevention performance will not be obtained, and if it exceeds 20 parts, a viscosity will become large and strength will become small.

Calcium carbonate contained in the classification cement is present as fine particles due to the classification, so that the reactivity is good. Calcium carbonate is usually used as a part of sand when producing cement fillers or concrete. Since the powder level of calcium carbonate (fine limestone powder) normally used is 4000-6000 cm <2> / g, it is finer than that, and the reaction activity is high, and the effect of strength improvement can also be expected. In addition, it reacts with calcium aluminate (3CaO? Al ₂ O ₃ ) contained in cement to produce monocarbonate or hemicarbonate. Gypsum also reacts with calcium aluminate (3CaO? Al ₂ O ₃ ) contained in cement to produce ethringite, but when a certain amount of calcium carbonate is present, the reaction of monocarbonate or hemicarbonate is excellent. It is thought that the effect that lingite converts into monosulfate is suppressed and durability is easy to be secured.

Classification cements can be used in all Portland cements such as ordinary Portland cement, crude steel Portland cement, low heat Portland cement, medium heat Portland cement, and sulfate resistant cement. It can be used if it satisfies the conditions of X and Y shown in the said this invention 1. The same applies to mixed cements such as fly ash cement and silica cement, and the same applies to refractory cements such as alumina cement.

The powder degree of classification cement is 7000-16000 cm <2> / g like blast furnace slag fine powder, and 9000-16000 cm <2> / g is preferable. If it is less than 7000 cm <2> / g, a bleeding ratio may become large and sufficient permeability may not be obtained, and when it exceeds 16000 cm <2> / g, manufacturing cost will become excessive and it is not practical.

As for the median diameter of a classification cement, 1-7 micrometers is preferable. For example, the median diameter may be measured by a laser diffraction particle size distribution analyzer. If it is less than 1 micrometer, manufacturing cost will become excessive and it is not practical, and if it exceeds 7 micrometers, a bleeding ratio will become large and there exists a possibility of impairing permeability.

The ratio of classification cement is 5-30 parts with respect to 100 parts of blast furnace slag fine powders, and 10-25 parts are preferable. If it is less than 5 parts by weight, sufficient strength developability may not be obtained. If it exceeds 30 parts by weight, permeability may be impaired.

The dispersing agent of this invention contains a polyacrylic-acid dispersing agent.

The polyacrylic acid-based dispersant of the present invention exhibits the effect of suppressing the sedimentation of particles when the suspension solution is used and the effect of imparting permeability. It is a copolymer containing the monomer of the following general formula (I), It is characterized by the above-mentioned.

CH ₂ = C (R ¹ ) COO (R ² O) nR ³ (I)

Here, in formula (I), R ¹ represents a hydrogen atom or a methyl group, and R ² O represents an oxyalkylene group having 2 to 4 carbon atoms, such as —CH ₂ CH ₂ O— or —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 added mole number (mole ') of an oxyalkylene group, it is an integer of 5-40, Preferably it is 7-35, More preferably, it is 9-30. When the added molar number n is too small, the dispersing force is insufficient. On the other hand, when too big | large, it will become a high melting point solid and handling will become difficult.

In addition, R <^3> represents a hydrogen atom or a C1-C5 alkyl group, for example, a methyl group, an ethyl group, a propyl group, a butyl group, etc. are mentioned.

Examples of the monomer include polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polybutylene glycol mono (meth) acrylate, and methoxy polyethylene glycol having an added mole number of alkylene oxide of 5 to 40 moles. Meth) acrylate, methoxy polypropylene glycol (meth) acrylate, methoxy polybutylene glycol (meth) acrylate, ethoxy polyethylene glycol (meth) acrylate, ethoxy polypropylene glycol (meth) acrylate, Methoxy polybutylene glycol (meth) acrylate, propoxy polyethylene glycol (meth) acrylate, etc. are mentioned, These 1 type can be used individually or in combination of 2 or more types. If the monomer represented by general formula (I) is contained, you may use the copolymer combined with the monomer component which has another chemical structure.

Among these, copolymers containing methoxy polyethylene glycol (meth) acrylate and methoxy polypropylene glycol (meth) acrylate are preferable from the standpoint of sedimentation prevention performance and penetration performance.

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

The melamine-based dispersant of the present invention is, for example, a dispersant obtained by a method of condensing melamine with sulfite and formaldehyde, followed by further condensation of formaldehyde. Alkali metal salts, such as sodium and potassium of melamine sulfonic-acid formaldehyde condensate, alkaline-earth metal salts, such as calcium and magnesium, etc. can also be used.

The melamine dispersant of the present invention is used in combination with a polyacrylic acid dispersant. When using together, 10-1000 parts are preferable with respect to 100 parts of polycarboxylic acid type dispersing agents, and, as for the ratio of a melamine type dispersing agent, 30-600 parts are more preferable. If it is less than 10 parts, the effect which the sedimentation prevention performance of particle | grains may improve synergistically may not be acquired, and when it exceeds 1000 parts, the sedimentation prevention performance may be impaired.

By using together with a melamine type dispersing agent, the effect which reduces the bleeding rate from immediately after kneading | mixing was discovered rather than using polyacrylic acid type dispersing agent alone. Therefore, since the dispersing performance of the particles is improved over a long time, the permeability to the simulated ground is also improved, and since the particles having uniform hydraulic properties are dispersed in the ground, a more firm and uniform improved body can be obtained.

The usage-amount of a dispersing agent is 0.1-3 parts with respect to a total of 100 parts of blast furnace slag fine powder and classification cement, and 0.3-2 parts are preferable. If it is less than 0.1 part, sufficient sedimentation prevention performance and permeability will not be acquired, and even if it exceeds 3 parts, an effect will become a place.

However, a well-known cement admixture can be used together with the hydraulic cement composition for ground injection of this invention in the range which does not adversely affect original performance. For example, AE agent, AE water reducer, high performance water reducer, high performance AE water reducer, fluidizing agent, coagulation delay agent, crude agent, antifoaming agent, thickener, waterproofing agent (re), expanding agent (re), steep hardening material, shrinkage reducing agent (re), rust preventive agent, And cement emulsion polymer emulsions, clay minerals, and the like.

The hydraulic cement composition for ground injection of the present invention is constructed in a milky state by adding water. The greater the amount of water added, the better the permeability, but there is a possibility that material separation is encouraged and the blockage is carried out in the pressurized hose, and if less, the viscosity of the cement milk becomes too large to impair the permeability. As for the optimum range of water to be used, 400-1500 parts are preferable with respect to a total of 100 parts of blast furnace slag fine powder, classification cement, and a dispersing agent, and 700-1200 parts are more preferable. If the amount of water to be used is in the above-described range, the bleeding rate after 60 minutes of cement milk can be made 2% or less by the method of the Civil Society Standard (JSCE F-522). When the bleeding rate exceeds 2%, the injection of the injection material may be stopped for 60 minutes or more, and clogging may occur when restarting is performed.

The time for kneading by adding water to the ground cemented cement composition for ground injection of the present invention is not particularly limited, but after adding a predetermined amount of water to the grout mixer and adding the ground cemented cement composition for injection of the present invention to 1 to 3 times. Knead for a minute and mix.

The injection site is not particularly limited as long as it is an improvement of the soft ground. For example, the injection site can be applied to the ground where various structures such as harbors, lakes and airports, urban areas with poor soils, and mountainous areas are located. It can be used for the purpose of water or water grout, anti-heaving grout, anti-sediment grout, blow-proof grout, earth pressure reducing grout, increased support capacity grout, anti-exhaust grout, and the like. Because of its good permeability, it can be applied to sandy soils containing stones, and also functions effectively as a liquefaction prevention measure.

The construction method of this invention is not specifically limited, The construction equipment used by normal chemical liquid injection can be used, What is necessary is just to conform to the injection design and construction method which are normally performed. For example, the cement milk adjusted with the mixer may be pumped through a hose with a pump, and the injection material may be inject | poured through the rod arrange | positioned in the ground. Although the rod used at this time is not specifically limited, A single pipe rod, a single pipe strainer rod, a double pipe rod, a double packer rod of a double pipe, etc. can be used.

The hydraulic cement composition for ground injection of the present invention is basically injected in one shot, but according to the condition and purpose of the ground, 1.5 shots or two are separately compressed by commercially available coagulation accelerators and other various admixtures. It can also be installed in a shot method.

Example  One

Classification cement was changed with respect to 100 parts of blast furnace slag powders as shown in Table 1, and 1.0 part of dispersing agents shown in Table 1 were added with respect to 100 parts of blast furnace slag fine powders and classification cements, and the hydraulic cement composition for ground injection was adjusted. Water was added to 850 parts with respect to 100 parts of the hydraulic cement composition for ground injection, and kneaded with a grout mixer for 2 minutes and mixed. The viscosity, bleeding rate, permeability, and compressive strength of the obtained cement milk were measured. The results are shown in Table 1.

<Used Material>

Blast furnace slag fine powder (a): Commercially available blast furnace slag fine powder, Blaine specific surface area 10500cm2 / g, Median diameter 3.6㎛

Classification Cement (e): After classification of ordinary Portland cement and calcium carbonate, the classification cement, Blaine specific surface area 9700㎠ / g, Median diameter 4.1㎛, Calcium carbonate content 11.3%

Dispersant (A): Commercially available polyacrylic acid-based dispersant (methoxypolyethylene glycol methacrylate), in general formula (I), R ¹ is a methyl group, R ² O is an oxyethylene group having 2 carbon atoms, and R ³ is Methyl group.

Dispersing agent (B): Dispersing agent which mix | blended 300 parts of melamine type dispersing agents made from Japan Sika Ltd. with respect to 100 parts of dispersing agents (A).

<Measurement method>

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

Bleeding rate: JSCE-F522-1999 Injection of prepacked concrete The bleeding rate and expansion rate of mortar were tested according to the test method (polyethylene bag method). The measurement was made after 0.5 hour, after 1 hour, and after 2 hours. The temperature at the time of the measurement is 25 degrees Celsius

Permeability: It complies with the preparation method of the specimen of the stabilized soil by the chemical liquid injection shown in JGS0831-2000. Infiltration conditions were observed when cement milk was injected into a simulated ground filled with Toyoura sand filled with 50mm in diameter and 1000mm in height, at a pressure of 0.05 MPa.

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

From Table 1, by blending a specific amount of the classification cement into the blast furnace slag powder of the present invention and using a polyacrylic acid-based dispersant, an injection material cement milk with a small bleeding ratio can be produced, and exhibits excellent permeability. It can be seen that the compressive strength is also well expressed. In particular, by using the dispersing agent (B) containing a polyacrylic acid type dispersing agent and a melamine type dispersing agent, it turns out that bleeding rate is reduced more and strength expression property is also improved.

Example  2

To 100 parts of fine blast furnace slag powders with different surface specific areas, 15 parts of different classification cements with different specific surface areas and 1.0 part of dispersant (A) were added to 100 parts of blast furnace slag fine powders and classification cements. Adjusted. Water was added to 850 parts with respect to 100 parts of the hydraulic cement composition for ground injection, and kneaded with a grout mixer for 2 minutes and mixed. The viscosity, bleeding rate, permeability, and compressive strength of the obtained cement milk were measured. The results are shown in Table 2.

<Used Material>

Blast furnace slag fine powder (b): Blaine specific surface area 6100㎠ / g, Median diameter 7.4㎛

Blast furnace slag fine powder (c): Blaine specific surface area 8200㎠ / g, Median diameter 4.8㎛

Blast furnace slag fine powder (d): Blaine specific surface area 15500㎠ / g, Median diameter 1.6㎛

Classification cement (f): After classifying ordinary cement and calcium carbonate, classify cement, Blaine specific surface area 6050㎠ / g, median diameter 8.6㎛, calcium carbonate content 9.9%

Classification cement (g): After classifying ordinary cement and calcium carbonate, classify cement, Blaine specific surface area 8300㎠ / g, median diameter 6.1㎛, calcium carbonate content 9.5%

Classification cement (h): After classifying cement and calcium carbonate, usually, classified cement, Blaine specific surface area 15800㎠ / g, median diameter 2.5㎛, calcium carbonate content 13.2%

It can be seen from Table 2 that by using a blast furnace slag fine powder having a specific surface area of 7000 cm 2 / g or more and a median diameter of 7 µm or less, and a classification cement, a small bleeding ratio, good permeability and excellent compressive strength were obtained. When both blast furnace slag fine powder and classified cement or one of them is less than 7000cm2 / g of the specific surface area of the blast, or more than 7㎛ in median diameter, the bleeding rate is increased, the permeability is poor, and the compressive strength Lowers.

Example  3

A classification cement having a different calcium carbonate content is added to 100 parts of blast furnace slag fine powder (a) as shown in Table 3, and 1.0 part of a dispersant (A) is added to 100 parts of the total blast furnace slag fine powder and classification cement for ground injection. The hydraulic cement composition was adjusted. Water was added to 850 parts with respect to 100 parts of the hydraulic cement composition for ground injection, and kneaded with a grout mixer for 2 minutes and mixed. However, for comparison, ordinary portland cement containing no calcium carbonate was classified, and after that, a predetermined amount of calcium carbonate having a blain specific surface area of 5500 cm 2 / 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.

<Used Material>

Calcium Carbonate: Joetsu Mining Co. Blaine Specific Surface Area 5500㎠ / g

Table 3 shows that when calcium carbonate is 6-20 parts (range of this invention) of 100 parts of classification cements, a bleeding rate is small and strength expression property is also large. On the other hand, when calcium carbonate is less than 6 parts out of 100 parts of the classification cement, or when it adds to a classification cement without classification even if content of calcium carbonate is in the range of this invention, a bleeding ratio becomes large and strength developability also tends to become small. It is recognized that the reaction activity is small. Therefore, since a particle | grain contains a specific amount of fine calcium carbonate, and forms a hard hardened | cured material, it is thought that long-term durability also improves.

Example  4

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

<Used Material>

Dispersing agent (C): Dispersing agent which mix | blended 10 parts of melamine type dispersing agents by Sika Ltd. of Japan with respect to 100 parts of dispersing agents (A).

Dispersing agent (D): Dispersing agent which mix | blended 30 parts of melamine type dispersing agents by Sika Ltd. of Japan with respect to 100 parts of dispersing agents (A).

Dispersing agent (E): Dispersing agent which mix | blended 100 parts of melamine type dispersing agents by Sika Ltd. of Japan with respect to 100 parts of dispersing agents (A).

Dispersing agent (F): Dispersing agent which mix | blended 600 parts of melamine type dispersing agents by Sika Ltd. of Japan with respect to 100 parts of dispersing agents (A).

Dispersing agent (G): Dispersing agent which mix | blended 1000 parts of melamine type dispersing agents by Sika Ltd. of Japan with respect to 100 parts of dispersing agents (A).

Dispersant (H): Naphthalene sulfonate-based dispersant Cellflow 110P made by DAI-ICHI SEIYAKU KOGYO Co., Ltd.

Dispersant (I): Lignin sulfonate-based dispersant Vanilex N manufactured by Nippon Paper Industries Co., Ltd.

Dispersant (J): Melamine-based dispersant Sikament FF manufactured by Sika Ltd. of Japan

<Measurement method>

Compressive strength deviation: Ten compressive strength test specimens were prepared by cutting a sand gel that penetrated into an acrylic pipe of 1000 m to a length of 100 mm to prepare 10 compressive strength test specimens.

From Table 4, it can be seen that by using the polyacrylic acid-based dispersant, the bleeding rate can be reduced and good permeability can be ensured. In particular, it is preferable to use together with a melamine type dispersing agent, and since the difference in compressive strength by the difference of a penetration distance becomes small, it is thought that it is possible to obtain a more uniform improved solidified body. When dispersants (naphthalene sulfonate dispersants, lignin sulfonate dispersants, melamine dispersants) other than polyacrylic acid dispersants are used alone, good permeability cannot 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 penetration test was performed using this cement milk, and the leak test of the cement milk which assumed the simulated ground with water flow was done. As for the evaluation items, when 7 days after the presence or absence of the flow of cement milk, the hardened | cured material was taken out from the simulated ground, and when it hardened | cured to the shape and substantially spherical shape, the diameter was confirmed. The test results are shown in Table 6.

<Test method>

Penetration-lowering test: It carried out based on the soil permeation test method shown in JGS0311-2000. The test conditions were filled with a φ10 × 23 cm transparent acrylic container with No. 5 silica sand so as to have a clearance rate of 40.5% to prepare a simulated ground. However, the bottom surface of the acrylic container for producing the simulated ground was set with a filter so that water or cement milk flowed out. The pipe was set so that cement milk was inject | poured in the vicinity of the center of the produced simulation ground, and it immersed in the container filled with the water by the manufactured simulation ground container. The submerged simulated ground container is set to 0.7 cm in water level difference between the upper end of the simulated ground container and the container filled with water, and the water is always replaced by supplying water, and 120cc of cement milk mixed by kneading from the pipe is injected. The leakage of cement milk from the simulated ground was observed. In addition, the state of the cement milk hardened | cured material which accumulated in the simulated ground disassembled the simulated ground container after 7 days of age, pulled out the hardened | cured material from the inside, and confirmed the shape and the diameter when it was hardened in substantially spherical form. The bleeding rate of the injection material before injection was also measured.

From Table 6, it can be seen that by using the cement composition for ground injection of the present invention, even if injected into the ground under flowing water, it is accumulated in the ground without flowing out, thereby forming a hardened body in a substantially theoretical manner. Moreover, since hardened | cured material is hardening in the ground in a substantially spherical state, uniform penetration injection is also performed. Moreover, it turns out that the change of the bleeding rate is small also if the quantity of water used is in the range of 400-1500 parts with respect to 100 parts of hydraulic cement compositions for ground injection.

Example  6

In the liquefaction measures construction of the breakwater foundation ground, actual construction using the cement composition for ground injection of this invention was performed. Construction method is experiment No. in grout mixer. Cement milk of 5-9, 5-11, 5-16 was adjusted and injected into the ground. Each cement milk was kneaded and mixed for 2 minutes, and once, it transferred to the storage tank, and it injected-injected through the hose and the injection pipe (single pipe rod) by the grout pump. Pressure management during the injection was 0.5 MPa at a maximum, the injection rate was 40%, and the injection amount was 1 m 3. All the cement cement milks could be injected under the control of the injection pressure. After one month, the ground was re-examined to confirm the hardening condition of the injected cement milk, and the cement cement infiltrated into the ground and hardened was observed. Either hardened | cured material was also a shape near the spherical shape whose diameter is 45-65 cm. When the sample was cut out from the hardened | cured material and the compressive strength was measured, experiment No. Injection material hardened | cured material corresponded to 5-9 is 3.5 N / m <3>, Experiment No. 5-11 is 1.4 N / dl, Experiment No. 5-16 was 0.4 N / Pa, and it turned out that there exists sufficient improvement effect.

Example  7

The cement composition for ground injection of the present invention is kneaded and mixed by using the equipment used in the liquefaction measures construction of the breakwater foundation ground shown in Example 6, and the injection material is stopped in the hose, and the injection material is suspended in the hose for 60 minutes. I was. After that, the starting state when the operation was started again was confirmed. The confirmed formulation was experiment no. Injection material cement milk of 5-9, 5-11, 5-13, 5-14, 5-18 (The amount of dough mixed is different.) As a comparison, experiment No. 5-1, 5-2, 5-3, 5-4, and 5-6 were implemented similarly. As a result, experiment No. The injected materials of 5-9, 5-11, 5-13, 5-14, and 5-18 had almost no sedimentation of particles in the hose, and were able to resume the pressure feeding smoothly without applying pressure at startup. On the other hand, Experiment No. which is a comparative example. In the injection material of 5-1, 5-2, 5-3, 5-4, and 5-6, the sedimentation of the particle | grains in the hose was confirmed. In particular, experiment No. About 5-4 and 5-5 were covered with the settled particle | grains about half of the hose cross section, and could not be restarted. Experiment No. Although 5-1, 5-2, and 5-3 were able to start, the blockage of the hose was large because a large amount of pressure at the start and large particles that do not disperse in the moisture after starting flowed through the hose. Looks like

The hydraulic cement composition for ground injection according to the present invention has a small material separation, excellent permeability, and makes it possible to rapidly improve workability and wide range. In addition, the cured body formed of the classification cement, finely divided slag, and dispersant having characteristics exhibits sufficient strength expression and excellent long-term durability, and therefore can be applied to various soft ground reinforcement works such as countermeasures for liquefaction of sandy soil.

Claims (7)

For 100 parts of blast furnace slag fine powder and 100 parts of blast furnace slag fine powder having a specific surface area of 7000-16000 cm2 / g and median diameter of 1-7 μm, the following conditions 5-30 parts of classification cement which satisfies all of the above, and a dispersing agent comprising 0.1-3 parts of polyacrylic acid-based dispersant based on 100 parts of the blast furnace slag fine powder and the classification cement in total. Hydraulic cement composition for injection.
분 a classification cement comprising 6 to 20 parts of calcium carbonate in 100 parts of the classification cement
분 classification cement, characterized in that the specific surface area of blast is 7000-16000cm2 / g
분 classification cement, characterized in that the median diameter is 1 ~ 7㎛ The method according to claim 1,
The hydraulic cement composition for ground injection, characterized in that the dispersant further contains a melamine-based dispersant. The method according to claim 1,
The above-mentioned polyacrylic acid-based dispersant is a copolymer containing a monomer of the general formula (I) below.
CH ₂ = C (R ¹ ) COO (R ² O) nR ³ (I)
(Wherein R ¹ represents a hydrogen atom or a methyl group, R ² O represents an oxyalkylene group having 2 to 4 carbon atoms, n represents an integer of 5 to 40, and R ³ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms) Cement milk characterized by kneading by adding water to the hydraulic cement composition for ground injection according to any one of claims 1 to 3. The method of claim 4,
Cement milk characterized in that the bleeding rate after 60 minutes of the cement milk mixed with water and kneaded by mixing the hydraulic cement composition for ground injection is 2% or less. A ground improvement method for injecting the cement milk according to claim 4 into the ground. The method of claim 6,
A soil improvement method characterized by being used for soil improvement for the purpose of liquefaction.