JP2023000210A - Liquid chemical for soil stabilization, method for producing liquid chemical for soil stabilization, and ground stabilization construction method - Google Patents

Abstract

To provide a liquid chemical for soil stabilization that has a small amount of bleeding even when the gel time is lengthened and can self-support in a short time, a method for producing the liquid chemical for soil stabilization, and a ground stabilization construction method.SOLUTION: Provided is a liquid chemical for soil stabilization that contains a main material liquid containing hydraulic cement, inorganic alkali metal carbonate and water, a hardening material liquid containing bentonite, alumina cement and water, and a gypsum in at least one of the main material liquid and the hardening material liquid. A method for producing liquid chemical for soil stabilization that comprises a step of mixing the main material liquid and the hardening material liquid. A ground stabilization construction method comprises injecting the liquid chemical for soil stabilization into the ground. A ground stabilization construction method comprises mixing the main material liquid and the hardening material liquid of the soil stabilizer in the ground.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a soil stabilization chemical, a method for producing the soil stabilization chemical, and a ground stabilization method.

Cement suspensions, in which cement is suspended in water, are used as soil stabilization chemicals that are injected into ground voids and the like to reinforce the ground, but cement suspensions have a slow setting speed. , which takes several hours to condense. In addition, the cement in the cement suspension settles before it hardens, making it impossible to harden the whole.

When the cement suspension is injected into the ground and used as a soil stabilization chemical, the fluidity of the cement suspension is ensured before it is injected into the ground and until the cement suspension is transported to a predetermined location. It is required that the liquidity disappears at a level where it can stand on its own after being transported to a predetermined place.

Therefore, recently, a chemical solution for stabilizing soil properties, which is prepared by mixing a hardening material liquid that improves the hardening speed of a cement suspension and a main material liquid, has been used.
In Patent Document 1, a chemical liquid for soil stabilization is produced by mixing a main material liquid containing hydraulic cement other than alumina cement, lime and water, and a hardening material liquid containing alumina cement, inorganic carbonate, bentonite, etc. is stated. The chemical solution for soil stabilization described in Patent Document 1 can shorten the time from mixing the main material liquid and hardening material liquid to hardening (hereinafter referred to as "gel time") within 10 seconds. It is said that

JP 2020-90622 A

Short gel time and excellent instant setting are desirable from the viewpoint of improving work efficiency, but depending on the application, such as when the distance from the manufacturing site of the soil stabilization chemical to the site to be stabilized is long. A gel time that is too short may cause problems.

However, in the soil stabilization chemical solution of Patent Document 1, if changes such as reducing the amount of lime are made in order to make the gel time longer than 10 seconds, there is a problem that the amount of bleeding of the solution after mixing increases. there were.

An object of the present invention is to provide a soil stabilizing chemical solution that can stand on its own in a short time with a small amount of bleeding even when the gel time is lengthened, a method for producing the soil stabilizing chemical solution, and a ground stabilization construction method. .

The gist of the present invention is the following [1] to [4].

[1] A main material liquid containing hydraulic cement, an inorganic alkali metal carbonate, and water, and a hardening material liquid containing bentonite, alumina cement, and water, and at least one of the main material liquid and the hardening material liquid Soil stabilization chemical containing gypsum.
[2] A method for producing a chemical solution for soil stabilization, comprising mixing a main material liquid containing hydraulic cement, an inorganic alkali metal carbonate and water with a hardening material liquid containing bentonite, alumina cement and water, A method for producing a chemical solution for stabilizing soil, wherein at least one of the main material solution and the hardening material solution contains gypsum.
[3] A ground stabilization method of injecting the soil stabilization chemical solution according to [1] into the ground.
[4] A ground stabilization method in which a main material liquid containing hydraulic cement, an inorganic alkali metal carbonate and water and a hardening material liquid containing bentonite, alumina cement and water are mixed in the ground, wherein the main material A ground stabilization method in which at least one of the liquid and the hardener liquid contains gypsum.

ADVANTAGE OF THE INVENTION According to the present invention, it is possible to provide a soil stabilizing chemical solution that can stand on its own in a short time with a small amount of bleeding even when the gel time is lengthened, a method for producing the soil stabilizing chemical solution, and a ground stabilization construction method. .

In the present specification, the term "solidified body" means a solidified substance of the soil stabilization chemical solution of the present invention in the ground.
In addition, "self-supporting" refers to a state in which the material does not flow out even when there is no support. The measured hardness of the soil stabilizing chemical is quantitatively indicated as a state in which the vane shear strength is 1.2 (kN/m ² ) or more.
In addition, the "stirring time" means the time from mixing of all the components to completion of stirring in the production of the main material liquid and the hardening material liquid.
The present invention will be described in detail below.

The chemical solution for soil stabilization of the present invention includes a main material liquid and a hardening material liquid. At least one of the main material liquid and the hardening material liquid according to the present invention contains gypsum.

(plaster)
In the main material liquid or the hardening material liquid according to the present invention, gypsum is a component that has the property of increasing the initial and final strength of the solidified body.

Examples of gypsum include various forms of gypsum, such as type II anhydrite, type III anhydrite, α-hemihydrate gypsum, β-hemihydrate gypsum, and dihydrate gypsum. In addition, natural gypsum or artificially produced or by-produced chemical gypsum (phosphoric gypsum, flue gas desulfurization gypsum, titanium gypsum, hydrofluoric gypsum, mineral water/smelting gypsum, etc.) may be used. Among them, type II anhydrite is preferable because the compressive strength of the solidified body is higher.

The Blaine value, which is an index of fineness of gypsum, is preferably 1,000 to 20,000 cm ² /g, more preferably 1,500 to 12,000 cm ² /g, even more preferably 2,500 to 10,000 cm ² /g. If the Blaine value of gypsum is equal to or higher than the above lower limit, the compressive strength of the solidified body will be higher. On the other hand, if it is equal to or less than the above upper limit, it is preferable in that scattering of the powder is suppressed and the volume of the powder is reduced. Moreover, if it is below the said upper limit, when it mixes with water, aggregation will become difficult to occur.
Only one type of gypsum may be contained, or two or more types may be contained in combination.

The content of the gypsum according to the present invention is preferably 0.5 to 20 kg, more preferably 1 to 10 kg, per 400 L of the total of the main material liquid and the hardening material liquid. If the gypsum content is at least the above lower limit, gelation is promoted, and the initial and final strength of the solidified body are increased. If it is less than the above upper limit, the viscosity of the main material liquid or the hardening material liquid is suppressed, so that pumping by a pump is facilitated, and the soil stabilizing chemical liquid described later can easily permeate the ground. Further, when the amount is equal to or less than the above upper limit, the volume of the solidified material can be increased with respect to the amount of components in the main material liquid or the hardening material liquid.

[Main liquid]
The main material liquid according to the present invention contains hydraulic cement, inorganic alkali metal carbonate, and water in addition to gypsum.

(hydraulic cement)
The hydraulic cement contained in the main material liquid according to the present invention is hydraulic cement other than alumina cement. Examples of the hydraulic cement include, for example, normal, high early strength, ultra high early strength, moderate heat and white Portland cement, blast furnace cement, silica cement, mixed cement such as fly ash cement, fine particle cement, ultra fine particle cement, ultra ultra Examples include fine particle cement and ground granulated blast furnace slag.
Hydraulic cement may contain only one of these, or may contain two or more in combination.

The content of hydraulic cement in the main liquid material according to the present invention is preferably 25 to 300 kg, more preferably 50 to 200 kg, and even more preferably 75 to 150 kg, per 200 L of the main liquid material. If the content of the hydraulic cement is at least the above lower limit, the compressive strength of the solidified body can be further increased. On the other hand, if the viscosity is equal to or less than the above upper limit, the viscosity of the main material liquid is suppressed, so that pumping by a pump becomes easy, and the main material liquid or the soil stabilizing chemical solution described later easily permeates the ground. Moreover, if the above upper limit value or less is used, the volume of the solidified material can be increased with respect to the amount of components in the main material liquid.

(Inorganic alkali metal carbonate)
The inorganic alkali metal carbonate is a component that has the property of accelerating hardening of the soil stabilization chemical of the present invention.

Examples of inorganic alkali metal carbonates include alkali metal carbonates such as Li ₂ CO ₃ , Na ₂ CO ₃ and K ₂ CO ₃ . Only one kind of inorganic alkali metal carbonate may be contained, or two or more kinds may be contained in combination. Among them, Na ₂ CO ₃ and K ₂ CO ₃ are preferable from the viewpoints of reducing bleeding, promoting gelation, and accelerating the rise of the strength of the solidified material.

The content of the inorganic alkali metal carbonate in the main liquid is preferably 2 to 12 kg, more preferably 4 to 10 kg, per 200 L of the main liquid. If the content of the inorganic alkali metal carbonate is within the above range, the hardening of the soil stabilization chemical can be accelerated and the strength of the solidified body can be increased quickly. Moreover, sedimentation of the main material liquid can be suppressed.

In order to bring out the effect of the present invention more effectively, it is preferable not to leave an undissolved portion of the inorganic alkali metal carbonate when the main material liquid is prepared.

(water)
Examples of the water of the main material liquid according to the present invention include tap water, industrial water, ground water, river water, and sea water. Among these, clean water and industrial water are preferable in order to fully exhibit the effects of the present invention.

(Other additives)
The main material liquid may contain other additives in addition to gypsum, inorganic alkali metal carbonate, and hydraulic cement other than alumina cement. Other additives include, for example, water reducing agents, antifoaming agents, thickening agents, and setting time adjusting agents.

Water-reducing agents include ligninsulfonates or derivatives thereof, polycarboxylic acids, aminosulfonic acids, oxyorganic acid salts, alkylarylsulfonates, polyoxyethylene alkyl ethers, polyol complexes, higher polyhydric alcohol sulfonates, Examples include various water reducing agents, dispersants, superplasticizers, and fluidizing agents containing melamine formalin condensates (sulfonates, modified methylols), naphthalene sulfonate formalin condensates, etc. as main components.
Only one type of water reducing agent may be contained, or two or more types may be contained in combination.

Antifoaming agents include, for example, higher alcohols, alkylphenols, diethylene glycol, dibutyl phthalate, water-insoluble alcohols, tributyl phosphate, polyglycols, silicones, and ethylene oxide-propylene oxide copolymers.
Only one type of antifoaming agent may be contained, or two or more types may be contained in combination.

Thickeners include, for example, cellulose ethers such as methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylmethylcellulose, hydroxybutylmethylcellulose, hydroxyethylethylcellulose, carboxymethylcellulose; polyacrylamide, sodium polyacrylate, polyacrylamide-poly acrylic polymers such as sodium acrylate copolymers and polyacrylamide partial hydrolysates; water-soluble polymers such as polyvinyl alcohol, polyethylene oxide, sodium alginate, casein and guar gum;
Only one type of thickener may be contained, or two or more types may be contained in combination.

Examples of setting time adjusters include oxycarboxylic acids such as citric acid, gluconic acid, tartaric acid, malic acid, lactic acid, glucoheptonic acid, oxymalonic acid, mucic acid, glucuronic acid, and lactobionic acid, and alkali metal salts thereof ( lithium salts, sodium salts, potassium salts, etc.); ammonium salts; aminocarboxylic acids such as glutamic acid, and alkali metal salts thereof (lithium salts, sodium salts, potassium salts, etc.); . Among these, at least one of oxycarboxylic acids and salts thereof is preferable, and citric acid, sodium citric acid, gluconic acid, and sodium gluconic acid are more preferable from the standpoint of rising gel strength immediately after gelation. .
Only one type of setting time adjusting agent may be contained, or two or more types may be contained in combination.

(Manufacturing method of main material liquid)
The main material liquid according to the present invention can be produced by dispersing each component in a desired blending amount in water using a known stirrer or the like.
The order in which the hydraulic cement, gypsum, inorganic alkali metal carbonate, water and other optional additives are mixed when producing the main material liquid is not particularly limited. In addition, after dispersing other additives such as inorganic alkali metal carbonate, gypsum, and optionally blended dispersant, defoamer, and setting speed adjuster in water, add hydraulic cement and wait for a predetermined time. A method of mixing by stirring is preferred. In addition, when the hardening material liquid contains gypsum, the main material liquid may not contain gypsum.

As a method of manufacturing the main material liquid at the construction site for ground stabilization, for example, gypsum, inorganic alkali metal carbonate, hydraulic cement and other additives that are blended as necessary are separately added to the construction site. After carrying in and mixing in a predetermined amount ratio, a method of adding water and mixing, generally distributed hydraulic cement, separately from that, other inorganic alkali metal carbonates, gypsum, and if necessary A method of bringing a mixture in which other additives are blended in advance at a predetermined amount ratio to the construction site, adding it to water and mixing, hydraulic cement, inorganic alkali metal carbonate, gypsum, and necessary A mixture of the main material preliminarily blended with other additives to be blended according to the requirements is brought into the construction site, and the mixture is added to water and mixed. Among these, the latter two methods are preferable because they can simplify the work at the construction site.

[Hardening material liquid]
The curing material liquid according to the present invention is a component used for curing the main material liquid.
The hardener liquid contains bentonite, alumina cement and water in addition to gypsum. The hardener liquid may contain other additives. Other additives include, for example, other additives in the above-described main material liquid.

Each component contained in the hardener liquid will be described below. As for the details of the other additives, the same compounds as those of the other additives in the above-described main material liquid can be used.

(alumina cement)
In the present invention, alumina cement is obtained by mixing a calcareous raw material (calcium content) and an alumina raw material (alumina content) and firing the mixture, or by melting the mixture, hardening it, and pulverizing it. It means all cement minerals obtained.

As the alumina cement, for example, the mixture of the calcareous raw material and the alumina raw material is melted and then quenched so that the main mineral composition is glassy (amorphous) C ₁₂ A ₇ , and the hardened product is obtained. Ground and gypsum-added mixtures are included. Here, the gypsum may be added while pulverizing the hardened material of the mixture, or may be added after pulverization of the hardened material is completed. The crystal form of the gypsum to be added may be type II or other forms.

Further, as another example of alumina cement, a mixture of the calcareous raw material and the alumina raw material is fired so that the main mineral composition is CA, or the mixture is melted and then quenched to form a hardened product. Examples include those obtained by pulverization. In addition to CA, the alumina cement of this example may contain, for example, C ₂ AS, C ₄ AF, etc. in addition to C ₁₂ A ₇ and CA ₂ , depending on the firing or melting conditions and impurities contained in the raw materials. minerals as optional components.

Further, specific examples of the alumina cement include, for example, alumina cements 1 to 5 specified in JIS R2511:1995 "alumina cement for refractories", or alumina cement having a quality equivalent thereto.

Among these, it is more preferable to use alumina cement of Class 3 or Class 4, or those having equivalent qualities.
As the alumina cement, for example, there is a cement composed mainly of calcium aluminate such as CA and _CA2 , and composed of compounds such as calcium aluminoferrite such as _C4AF and calcium aluminosilicate such as _C2AS . mentioned.

In the examples of the above chemical formulas, "A" stands for _Al2O3 , " _C " stands for CaO, "F" stands for _{Fe2O3 ,} and "S" stands for _SiO2 . .

(bentonite)
The bentonite used in the present invention is a component that suppresses the bleeding of the chemical liquid after mixing the main material liquid and the hardening material liquid. There are various brands of bentonite depending on the place of origin and processing, and these may contain only one type or a combination of two or more types.

(water)
Examples of water include tap water, industrial water, ground water, river water, and sea water. Among these, clean water and industrial water are preferable in order to fully exhibit the effects of the present invention.

(Content of each component in hardener liquid)
The content of alumina cement in the hardening material liquid is preferably 1 to 50 kg, more preferably 2 to 30 kg, and even more preferably 4 to 15 kg per 200 L of hardening material liquid. If the content of the alumina cement is at least the above lower limit, the minimum stirring time required for developing a stable gel time will be shortened, and the compressive strength of the compact will be higher. On the other hand, if it is equal to or less than the above upper limit, the viscosity of the hardening material liquid is suppressed, so that the main material liquid and the hardening material liquid are mixed more uniformly, and variations in the compressive strength of the solidified body are further reduced. Further, when the content is equal to or less than the above upper limit, pumping by a pump is facilitated, and the hardening material liquid or the soil stabilizing chemical liquid to be described later is easily permeated into the ground.

The content of bentonite in the hardening material liquid is preferably 2 to 20 kg, more preferably 5 to 12 kg, per 200 L of the hardening material liquid. If the content of bentonite is within the above range, the amount of bleeding after mixing the main material liquid and the hardening material liquid can be suppressed. If it is at least the above lower limit, the amount of bleeding after mixing is suppressed, and sedimentation of the hardening material liquid itself is also suppressed. On the other hand, if it is equal to or less than the above upper limit, the viscosity of the hardening material liquid is suppressed, so that stirring and pumping by a pump are facilitated. Moreover, if the above upper limit value or less is used, the volume of the solidified body can be increased with respect to the amount of components in the hardening material liquid.

When the hardening material liquid according to the present invention contains gypsum, the content of gypsum is preferably 0.5 to 20 kg, more preferably 1 to 10 kg, per 200 L of the hardening material liquid. If the gypsum content is at least the above lower limit, gelation will be promoted, and the initial and final strength of the solidified body will be increased. If the viscosity is equal to or less than the above upper limit, the viscosity of the main material liquid can be kept low, which facilitates pumping by a pump and facilitates the penetration of the main material liquid or the soil stabilizing chemical solution described later into the ground. Moreover, if the above upper limit value or less is used, the volume of the solidified material can be increased with respect to the amount of components in the main material liquid.
When the main material liquid contains gypsum, the hardening material liquid may not contain gypsum.

When the hardening material liquid according to the present invention contains a water reducing agent, the content of the water reducing agent is preferably 1 to 30% by mass, more preferably 4 to 20% by mass, based on the bentonite.

(Method for producing hardener liquid)
The hardening material liquid is produced by dispersing components other than water in the hardening material liquid (hereinafter also referred to as "hardening material") in water using a known stirrer or the like. Examples of the dispersion method include a method of dispersing a premixed mixture of hardeners in water, and a method of dispersing hardeners in water in an arbitrary order.

Although the order of dispersing alumina cement and bentonite in water is not limited, it is preferable to disperse alumina cement after dispersing bentonite in water in order to suppress bleeding. Adding the alumina cement after the bentonite has been swollen with water gives it a higher viscosity and less bleeding.

When the hardening material is mixed in advance, the components of each hardening material may be mixed in a desired blending amount using a generally used mixer. The mixer used may be a mixer fixed at a factory or construction site, or a mixer mounted on a mixer truck.
Each component is preferably thoroughly mixed. By thoroughly mixing each component, a homogeneous curing material liquid can be quickly produced.

[Soil stabilization chemical]
The chemical solution for soil stabilization of the present invention contains the main material liquid and the hardening material liquid, and either the main material liquid or the hardening material liquid contains gypsum. Both may contain gypsum.

[Method for producing chemical solution for soil stabilization]
As a method for producing the soil stabilization chemical solution of the present invention, for example, a method of dispersing each component in water using a known stirrer or the like; ), a method of adding components other than water in the main material liquid to the hardening material liquid, and a method of mixing the main material liquid and the hardening material liquid. Among them, the method of mixing the main material liquid and the hardening material liquid is preferable as the method for producing the soil stabilizing chemical liquid from the viewpoint of stabilizing the workability and gel time at the construction site.

The main material liquid and the hardening material liquid may be mixed before pouring into the ground, or may be carried out while pouring each liquid into the ground. In the case of performing before pouring into the ground, the main material liquid and the hardening material liquid may be mixed by a general stirring method using a stirrer or the like that is commonly used when manufacturing cement. When mixing the main material liquid and the hardening material liquid while injecting them into the ground, for example, the main material liquid and the hardening material liquid are separately pumped using pumps having the same liquid feeding capacity per unit time. Stirrer, method of pumping and mixing in a mixing chamber (in-pipe mixer/pipe mixer) provided in the injection pipe, main liquid and hardening material liquid separately in the inner and outer pipes of the double pipe. For example, a method in which the liquid is fed and the main material liquid and the hardening material liquid are combined and mixed in the ground at the time of injection. In order to prevent the main material liquid and the hardening material liquid from hardening during injection, the soil stabilizing liquid is preferably produced immediately before or while injecting, more preferably while injecting.

From the viewpoint of easy construction, the volume ratio when mixing the main material liquid and the hardening material liquid is preferably 7:3 to 3:7, more preferably 6:4 to 4:6, and an equal volume of 5:5. is more preferred.

[Ground stabilization method]
The ground stabilization method of the present invention has a first aspect of injecting the soil stabilization chemical solution into the ground and a second aspect of mixing the main material liquid and the hardening material liquid in the ground.
A specific method of the first aspect includes, for example, a method of obtaining a soil stabilizing chemical in the same manner as in the method for producing the soil stabilizing chemical, and injecting the soil stabilizing chemical into the ground.
A specific method of the second aspect includes, for example, a method in which the main material liquid and the hardening material liquid are injected into the ground through separate injection pipes, and the two liquids are merged and mixed in the ground. In this embodiment, injection can be performed at a pressure of 50 to 1000 kg/cm ² using an injection pipe having an injection nozzle.

[Effect]
ADVANTAGE OF THE INVENTION According to the present invention, it is possible to provide a soil stabilizing chemical solution that can stand on its own in a short time with a small amount of bleeding even when the gel time is lengthened, a method for producing the soil stabilizing chemical solution, and a ground stabilization construction method. .
The effect of the present invention is presumed to be due to the following mechanism.

The hardening material liquid obtained by the reaction of the swollen bentonite and the alumina cement and preventing sedimentation is mixed with the main material liquid in which the inorganic alkali metal carbonate and the hydraulic cement are mixed in advance. It is presumed that as a result of suppressing sedimentation of the soil stabilizing chemical, the amount of bleeding decreased even when the gel time was lengthened, and it became possible to stand on its own in a short period of time.

In addition, it is presumed that due to the action of alumina cement, gypsum, and inorganic alkali metal carbonate, the generation of ettringite and the like is hastened and hardening is accelerated, making it possible to stand on its own in a short period of time.

In the present invention, the amount of breathing has a different value depending on the gel time, and the gel time has a different value depending on the component composition of the soil stabilizing chemical. In the soil stabilizing solution having a relatively long gel time, the breathing amount can be 3% or less, preferably 1% or less.
The gel time of the soil stabilizing chemical solution of the present invention varies depending on the component composition, but can usually be about 5 to 60 minutes. Moreover, there is no particular limitation on the lower limit of the amount of breathing.

Here, the breathing amount is the amount (volume) of floating water of the chemical solution that remains as a supernatant when the soil stabilization chemical solution reaches the gel time with respect to the volume of the soil stabilization chemical solution (the total of the main material liquid and the hardening material liquid). It is a ratio (percentage) and is measured by the method described in the Examples section below.

EXAMPLES The present invention will be described in more detail below using Examples and Comparative Examples, but the present invention is not limited to these Examples.
Materials used in the following examples and comparative examples, preparation methods of the main material liquid and the hardening material liquid, and various measurement and evaluation methods are as follows.

[material]
(main liquid)
・Hydraulic cement: Ordinary Portland cement ・Anhydrous sodium carbonate (Na ₂ CO ₃ )
Anhydrous potassium carbonate _{( K2CO3} )
・Gypsum: type II anhydrite (Blaine value: 6500 cm ² /g)
・Water: tap water

(Hardening material liquid)
・Alumina cement: JIS-R2511, Class 3 ・Bentonite (Haruna manufactured by Hojun Co., Ltd.)
・Bentonite (Neo Clay manufactured by Hojun Co., Ltd.)
・Water reducing agent: sodium naphthalene sulfonate・formaldehyde condensate ・Water: tap water

[Preparation method of main material liquid]
Using materials whose temperature has been adjusted to 20°C, in a room at 20°C, anhydrous sodium carbonate or anhydrous potassium carbonate (however, in Comparative Examples 1 and 3, no inorganic alkali metal carbonate is used) and gypsum (however, the implementation Gypsum was not used in Example 4 and Comparative Example 2) was dispersed in water, then ordinary Portland cement was dispersed and stirred to obtain a main material liquid. Stirring was carried out by using a magnetic stirrer, putting a 4 cm long stirrer bar into a 200 mL disk cup, containing 200 mL of the main material liquid, and performing the stirring at a rotation speed of 650 to 750 rpm for a predetermined period of time.
Table 1 shows the content of each component in the main material liquid.
In the present examples and comparative examples, experiments were conducted by preparing the main material liquid immediately before preparing the hardening material liquid.

[Method for preparing hardener liquid]
Using a material whose temperature has been adjusted to 20 ° C., bentonite and a water reducing agent are dispersed in water in a room at 20 ° C. After stirring for 3 minutes, alumina cement (in Examples 4 and 5, further gypsum, in Comparative Example 3, further anhydrous carbonic acid sodium) was added and stirred to obtain a hardener liquid. In Comparative Example 4, only alumina cement was added to water and stirred. Stirring was performed using a magnetic stirrer with a stirrer bar having a length of 4 cm placed in a 200 mL disc cup and containing 200 mL of the hardening material liquid at a rotation speed of 650 to 750 rpm for a predetermined period of time.
Table 1 shows the content of each component in the hardener liquid.

[Measurement of gel time]
100 mL of the obtained main material liquid and 100 mL of the hardening material liquid were put into 200 mL disc cups A and B, respectively. The liquid was immediately transferred to the disc cup A containing the main material liquid, and further transferred to the disc cup B containing the hardening material liquid. The cup was tilted every 5 minutes, and the gel time was defined as the time until the liquid surface did not move even when tilted at 45°.

[Measurement of breathing amount]
100 mL of the obtained main material liquid and 100 mL of the hardening material liquid were put into 200 mL disc cups A and B, respectively. The liquid was immediately transferred to the disc cup A containing the main material liquid, and further transferred to the disc cup B containing the hardening material liquid. After 1 hour, the water generated in the upper part due to sedimentation was collected in a graduated cylinder, and the amount of breathing was calculated by the following formula.
Amount of breathing (%) = (Amount of collected water (mL)/200 (mL)) x 100

[Measurement of hardness of chemical solution after 1 hour]
It was measured using a vane shear tester (torque driver-FTD-10CN-S: manufactured by Tohnichi Seisakusho Co., Ltd., vane blade: D15 mm×H30 mm).
Prepare 100 mL each of the main liquid and the hardening liquid in 200 mL discs A and B, and pour the entire amount of the main liquid into the disc B containing the hardening liquid. It was transferred to the disc cup A containing the main material liquid, and further transferred to the disc cup B containing the hardening material liquid and allowed to stand as it was. After this mixture was allowed to stand still for 1 hour, a vane blade was inserted into the center of the disc B and rotated, and the shear strength of the vane was calculated from the maximum scale value (maximum torque value) using the following formula.
Vane shear strength (kN/m ² )
= Tmax (kN·m)/(π×(D ² H/2+D ³ /6))
Tmax: Maximum torque value D: Width of vane blade (m)
H: Height of vane blade (m)
The self-sustainable value was 1.2 (kN/m ² ) or more in terms of vane shear strength.

[Examples 1 to 5 and Comparative Examples 1 to 4]
In Examples 1 to 5 and Comparative Examples 1 to 4, using the main material liquid and the hardening material liquid prepared as described above with the components shown in Table 1 and the contents of the components, gel time, breathing amount and Each evaluation item was evaluated by measuring the hardness of the chemical after 1 hour.
Each evaluation result is described in Table 1.
All evaluations were performed at a temperature of 20°C.

In Examples 1 to 5 using the soil stabilizing chemical of the present invention, the amount of bleeding was small even when the gel time was increased to 20 minutes, and the hardness of the chemical in 1 hour was higher than 1.2 (kN/m ² ). It was able to grow and become independent. In particular, Examples 1 and 2, in which sodium carbonate and gypsum were added to the main material liquid, had a low bleeding amount of 1% or less, and became self-supporting after 1 hour. Furthermore, in Example 5, in which gypsum was added to both the main material liquid and the hardening material liquid, the amount of bleeding was as small as 1% or less, and the strength increased as well as the self-standing after 1 hour.
On the other hand, in Comparative Example 1, in which the chemical solution for stabilizing soil was used which contained no inorganic alkali metal carbonate in either the main material solution or the hardening material solution, the chemical solution was soft after 1 hour and it was impossible to stand on its own. In addition, in Comparative Example 3, in which an inorganic alkali metal carbonate is included in the main material liquid instead of the hardening material liquid, the chemical liquid after 1 hour has a hardness that allows it to stand on its own, but the bleeding amount is 3% or more, which is bad. became. In Comparative Example 2, in which a soil stabilizing chemical solution containing neither gypsum nor hardening material liquid was used, hardening did not proceed and the bleeding amount could not be measured.
Also, in Comparative Example 4, in which the curing material liquid did not contain bentonite, the amount of breathing increased.

The chemical solution for soil stabilization, the method for producing the chemical solution, and the ground stabilization method of the present invention inject the chemical solution into voids in the ground, voids between embankments and the ground, cavities created by liquefaction, cavities behind tunnels, and the like. It is industrially very useful because it can be suitably used in the field of reinforcing the ground by

Claims (4)

It contains a main material liquid containing hydraulic cement, an inorganic alkali metal carbonate and water, and a hardening material liquid containing bentonite, alumina cement and water, and at least one of the main material liquid and the hardening material liquid contains gypsum. Chemical solution for soil stabilization. A method for producing a chemical solution for soil stabilization, comprising a step of mixing a main material liquid containing hydraulic cement, an inorganic alkali metal carbonate, and water with a hardening material liquid containing bentonite, alumina cement, and water, wherein the main material A method for producing a soil stabilizing chemical liquid containing gypsum in at least one of the liquid and the hardener liquid. A ground stabilization method of injecting the soil stabilization chemical solution according to claim 1 into the ground. A ground stabilization method for mixing a main material liquid containing hydraulic cement, an inorganic alkali metal carbonate and water and a hardening material liquid containing bentonite, alumina cement and water in the ground, wherein the main material liquid and the A ground stabilization method in which at least one of hardener liquids contains gypsum.