Soil stabilization chemicals, manufacturing method for soil stabilization chemicals, and ground stabilization method

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]

[0001] The present invention relates to a soil stabilization chemical solution, a method for producing the soil stabilization chemical solution, and a ground stabilization method. [Background technology]

[0002] Cement suspensions, which are made by suspending cement in water, are used as soil stabilization chemicals to be injected into voids in the ground to reinforce the ground, but the cement suspension has a slow setting speed and takes several hours to set. Also, the cement in the cement suspension settles during the setting process, making it impossible for the suspension to harden completely.

[0003] When a cement suspension is injected into the ground to be used as a soil stabilization liquid, it is required that the fluidity of the cement suspension be maintained before injection into the ground and until the cement suspension is transported to the designated location, and that the fluidity be reduced to a level that allows the suspension to stand on its own after transportation to the designated location.

[0004] Recently, therefore, a soil stabilization liquid has come into use, which is made by mixing a hardener liquid, which improves the hardening speed of the cement suspension, with a main liquid. Patent Document 1 describes the production of a soil stabilization liquid by mixing a main liquid containing hydraulic cement other than alumina cement, lime, and water with a hardening liquid containing alumina cement, inorganic carbonate, bentonite, etc. The soil stabilization liquid described in Patent Document 1 is said to be capable of shortening the time from mixing the main liquid with the hardening liquid to hardening (hereinafter referred to as "gel time") to within 10 seconds. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-90622 A Summary of the Invention [Problem to be solved by the invention]

[0006] While a short gelling time and excellent instant setting properties are desirable from the standpoint of improving work efficiency, in some applications, such as when the distance between the manufacturing site of the soil stabilization solution and the site to be stabilized is long, a gelling time that is too short may cause inconvenience.

[0007] However, the soil stabilization liquid of Patent Document 1 had a problem in that if changes were made, such as reducing the amount of lime, to extend the gel time beyond 10 seconds, the liquid would bleed a lot after mixing.

[0008] The present invention aims to provide a soil stabilization liquid that has a small amount of bleeding even when the gel time is extended and can stand on its own in a short time, a method for producing the soil stabilization liquid, and a ground stabilization method. [Means for solving the problem]

[0009] The present invention relates to the following [1] to [4].

[0010] [1] A soil stabilization chemical solution comprising a base liquid containing hydraulic cement, an inorganic alkali metal carbonate, and water, and a hardening liquid containing bentonite, alumina cement, and water, wherein at least one of the base liquid and the hardening liquid contains gypsum. [2] A method for producing a soil stabilization chemical solution, comprising a step of mixing a main liquid containing hydraulic cement, an inorganic alkali metal carbonate, and water with a hardening liquid containing bentonite, alumina cement, and water, wherein at least one of the main liquid and the hardening liquid contains gypsum. [3] A ground stabilization method in which the soil stabilization chemical solution described in [1] is injected into the ground. [4] A ground stabilization method in which a main liquid containing hydraulic cement, an inorganic alkali metal carbonate, and water is mixed with a hardening liquid containing bentonite, alumina cement, and water in the ground, wherein at least one of the main liquid and the hardening liquid contains gypsum. Effect of the Invention

[0011] According to the present invention, it is possible to provide a soil stabilization liquid that has a small amount of bleeding even when the gel time is extended and can stand on its own in a short time, a manufacturing method for said soil stabilization liquid, and a ground stabilization method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] In this specification, the term "solidified body" refers to a soil stabilization solution of the present invention that has coagulated within the ground. The term "self-supporting" refers to a state in which the material does not flow out even when the support is removed. For example, in the present invention, this state is defined as a vane shear strength of 1.2 (kN / m) as the hardness of the soil stabilization chemical solution measured by the method described in the Examples section below. 2 ) or greater. Moreover, the "mixing time" means the time from mixing all the components to finishing the mixing in the production of the main liquid material and the hardener liquid, respectively. The present invention will be described in detail below.

[0013] The soil stabilization liquid of the present invention includes a main liquid and a hardening liquid. At least one of the main liquid and the hardening liquid according to the present invention includes gypsum.

[0014] (plaster) In the main liquid material or hardener liquid according to the present invention, gypsum is a component having the property of increasing the initial and final strength of the solidified body.

[0015] Examples of gypsum include gypsum in various forms such as type II anhydrous gypsum, type III anhydrous gypsum, α-hemihydrate gypsum, β-hemihydrate gypsum, dihydrate gypsum, etc. In addition, natural gypsum and artificially manufactured or by-produced chemical gypsum (phosphate gypsum, flue gas desulfurization gypsum, titanic gypsum, hydrofluoric gypsum, mineral water / smelting gypsum, etc.) may be used. Among them, type II anhydrous gypsum is preferred because the compressive strength of the solidified body is higher.

[0016] The Blaine value, which is an index of the fineness of gypsum, is 1000 to 20000 cm2 / g is preferred, and 1500 to 12000 cm 2 / g is more preferable, and 2500 to 10000 cm 2 / g is more preferable. If the Blaine value of the gypsum is equal to or greater than the lower limit, the compressive strength of the solidified body will be higher. On the other hand, if the Blaine value is equal to or less than the upper limit, scattering of the powder is suppressed and the volume of the powder is reduced, which is preferable. Also, if the Blaine value is equal to or less than the upper limit, aggregation is less likely to occur when mixed with water. The gypsum may be contained in a single type or in a combination of two or more types.

[0017] The content of 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 liquid material and the hardener liquid. If the content of gypsum is equal to or more than the lower limit, gelation is promoted, and the initial and final strength of the solidified body is increased. If the content is equal to or less than the upper limit, the viscosity of the main liquid material or the hardener liquid is suppressed, making it easier to pump the liquid material, and the soil stabilization liquid described below is more likely to penetrate into the ground. If the content is equal to or less than the upper limit, the volume of the solidified body relative to the amount of components in the main liquid material or the hardener liquid can be increased.

[0018] [Main liquid] The main liquid according to the present invention contains, in addition to gypsum, hydraulic cement, an inorganic alkali metal carbonate, and water.

[0019] (hydraulic cement) The hydraulic cement contained in the main liquid according to the present invention is a hydraulic cement other than alumina cement. Examples of the hydraulic cement include ordinary, early strength, super early strength, moderate heat and white Portland cement, blast furnace cement, silica cement, mixed cement such as fly ash cement, fine particle cement, ultrafine particle cement, ultra-ultrafine particle cement and ground granulated blast furnace slag. The hydraulic cement may contain only one of these, or may contain a combination of two or more of them.

[0020] The content of hydraulic cement in the main liquid 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. If the content of hydraulic cement is equal to or greater than the lower limit, the compressive strength of the solidified body can be increased. On the other hand, if the content is equal to or less than the upper limit, the viscosity of the main liquid is suppressed, making it easier to pump the main liquid or the soil stabilization liquid described below more likely to permeate the ground. If the content is equal to or less than the upper limit, the volume of the solidified body relative to the amount of components in the main liquid can be increased.

[0021] (Inorganic alkali metal carbonates) The inorganic alkali metal carbonate is a component that has the property of promoting hardening of the soil stabilization solution of the present invention.

[0022] Examples of inorganic alkali metal carbonates include carbonates of alkali metals such as Li2CO3, Na2CO3, and K2CO3. Only one type of inorganic alkali metal carbonate may be contained, or two or more types may be contained in combination. Among them, Na2CO3 and K2CO3 are preferred from the viewpoints of reducing bleeding, promoting gelation, and accelerating the rise of strength of the solidified body.

[0023] The content of 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 inorganic alkali metal carbonate is within the above range, the hardening of the soil stabilization chemical solution can be promoted, and the strength of the solidified body can be increased quickly. In addition, the sedimentation of the main liquid can be suppressed.

[0024] In order to maximize the effect of the present invention, it is preferable that when the main liquid is prepared, no insoluble inorganic alkali metal carbonate remains.

[0025] (water) Examples of the water used as the main liquid in the present invention include tap water, industrial water, groundwater, river water, and seawater. Among these, tap water and industrial water are preferred in order to fully exert the effects of the present invention.

[0026] (Other additives) The main liquid may contain other additives in addition to gypsum, inorganic alkali metal carbonate, and hydraulic cement other than alumina cement, such as a water reducing agent, a defoaming agent, a thickening agent, and a setting time regulator.

[0027] Examples of water-reducing agents include various water-reducing agents, dispersants, high-performance water-reducing agents, and fluidizing agents whose main components are lignin sulfonate or a derivative thereof, polycarboxylic acid, aminosulfonic acid, oxyorganoacid salt, alkylarylsulfonate, polyoxyethylene alkyl ether, polyol complex, higher polyhydric alcohol sulfonate, melamine-formaldehyde condensate (sulfonate, modified methylol), and naphthalene sulfonate-formaldehyde condensate. The water reducing agent may be contained alone or in combination of two or more kinds.

[0028] Examples of the antifoaming agent include higher alcohols, alkylphenols, diethylene glycol, dibutyl phthalate, water-insoluble alcohols, tributyl phosphate, polyglycols, silicones, and ethylene oxide-propylene oxide copolymers. The antifoaming agent may be contained alone or in combination of two or more kinds.

[0029] Examples of thickeners include cellulose ethers such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxybutyl methyl cellulose, hydroxyethyl ethyl cellulose, and carboxymethyl cellulose; acrylic polymers such as polyacrylamide, sodium polyacrylate, polyacrylamide-sodium polyacrylate copolymers, and partial hydrolysates of polyacrylamide; and water-soluble polymers such as polyvinyl alcohol, polyethylene oxide, sodium alginate, casein, and guar gum. The thickener may be contained alone or in combination of two or more kinds.

[0030] Examples of setting time regulators 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 their alkali metal salts (lithium salt, sodium salt, potassium salt, etc.); ammonium salts; aminocarboxylic acids such as glutamic acid, and their alkali metal salts (lithium salt, sodium salt, potassium salt, etc.); and organic carboxylates such as ammonium salts. Among these, at least one of oxycarboxylic acids and their salts is preferred from the viewpoint of the rise in gel strength immediately after gelation, and citric acid, sodium salt of citric acid, gluconic acid, and sodium salt of gluconic acid are more preferred. The setting time regulator may be contained alone or in combination of two or more kinds.

[0031] (Method of manufacturing the main liquid) The main liquid material according to the present invention can be produced by dispersing the components in desired amounts in water using a known stirrer or the like. When producing the main liquid material, the order in which hydraulic cement, gypsum, inorganic alkali metal carbonate, water, and other additives as optional components are mixed is not particularly limited. A preferred method is to disperse the inorganic alkali metal carbonate, gypsum, and other additives such as dispersants, antifoaming agents, and setting speed regulators, which are added as necessary, in water, add hydraulic cement, and stir and mix for a predetermined period of time. When the hardener liquid contains gypsum, the main liquid material does not need to contain gypsum.

[0032] Examples of methods for producing a base liquid at a construction site where ground stabilization is performed include a method of separately transporting gypsum, inorganic alkali metal carbonate, hydraulic cement, and other additives to be mixed as necessary to the construction site, mixing them in a predetermined ratio, and then adding water to mix them; a method of transporting a mixture of commonly available hydraulic cement, other inorganic alkali metal carbonate, gypsum, and other additives to be mixed as necessary in a predetermined ratio to the construction site, adding it to water, and mixing it; and a method of transporting a base mixture of hydraulic cement, inorganic alkali metal carbonate, gypsum, and other additives to be mixed as necessary in a predetermined ratio to the construction site, adding it to water, and mixing it. Among these, the latter two methods are preferred because they simplify the work at the construction site.

[0033] [Curing material liquid] The hardener liquid according to the present invention is a component used for hardening the main liquid material. The hardener liquid contains bentonite, alumina cement, and water in addition to gypsum. The hardener liquid may contain other additives. Examples of the other additives include the other additives in the main liquid.

[0034] Each component contained in the hardener liquid will be described below. Regarding the details of the other additives, the same compounds as the other additives in the main liquid can be used.

[0035] (Alumina cement) In the present invention, alumina cement refers to all cement minerals obtained by mixing a calcareous raw material (calcium content) with an aluminous raw material (alumina content) and firing the mixture, or by melting the mixture, hardening it, and then pulverizing it.

[0036] The alumina cement is, for example, a material having a glassy (amorphous) mineral composition. 12A mixture of the calcareous raw material and the aluminous raw material is melted and then quenched, the hardened product is crushed, and gypsum is added to the mixture so as to obtain A7. Here, the gypsum may be added while the hardened product of the mixture is being crushed, or may be added after the crushing of the hardened product is completed. The crystal form of the gypsum to be added may be type II or another form.

[0037] Another example of alumina cement is one obtained by firing a mixture of the calcareous raw material and the aluminous raw material, or by melting the mixture and then quenching it, and pulverizing the hardened material, so that the main mineral composition is CA. The alumina cement of this example may contain, in addition to CA, for example, the above-mentioned C, depending on the firing or melting conditions and the influence of impurities contained in the raw materials. 12 In addition to A7 and CA2, minerals such as C2AS and C4AF may be included as optional components.

[0038] Further, specific examples of the alumina cement include alumina cement types 1 to 5 defined in JIS R2511:1995 "Alumina cement for refractories" or alumina cement having a quality equivalent thereto.

[0039] Among these, it is more preferable to use alumina cement type 3 or 4, or one having a quality equivalent thereto. Examples of the alumina cement include cements that contain calcium aluminates such as CA and CA2 as the main component, and are composed of compounds such as calcium aluminoferrites such as C4AF, and calcium aluminosilicates such as C2AS.

[0040] In the above examples of each chemical formula, "A" is an abbreviation for Al2O3, "C" is an abbreviation for CaO, "F" is an abbreviation for Fe2O3, and "S" is an abbreviation for SiO2.

[0041] (Bentonite) The bentonite used in the present invention is a component that suppresses bleeding of the chemical solution after mixing the main liquid and the hardener liquid. There are various brands of bentonite depending on the place of origin and processing, and only one of these may be contained, or two or more types may be contained in combination.

[0042] (water) Examples of water include tap water, industrial water, groundwater, river water, seawater, etc. Among these, tap water and industrial water are preferred in order to fully exert the effects of the present invention.

[0043] (Content of each component in the hardener liquid) The content of alumina cement in the hardener 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 the hardener liquid. If the content of alumina cement is equal to or greater than the lower limit, the minimum mixing time required for stable gel time is shortened and the compressive strength of the solidified body is increased. On the other hand, if the content is equal to or less than the upper limit, the viscosity of the hardener liquid is suppressed, so that the main liquid and the hardener liquid are mixed more uniformly and the variation in the compressive strength of the solidified body is reduced. If the content is equal to or less than the upper limit, pumping by a pump becomes easy, and the hardener liquid or the soil stabilization liquid described later can easily penetrate into the ground.

[0044] The content of bentonite in the hardener liquid is preferably 2 to 20 kg, more preferably 5 to 12 kg, per 200 L of the hardener liquid. If the content of bentonite is within the above range, the amount of bleeding after mixing the main liquid and the hardener liquid can be suppressed. If the content is equal to or greater than the above lower limit, the amount of bleeding after mixing is suppressed, and the settling of the hardener liquid itself is also suppressed. On the other hand, if the content is equal to or less than the above upper limit, the viscosity of the hardener liquid is suppressed, making it easier to stir and pump. Also, if the content is equal to or less than the above upper limit, the volume of the solidified body relative to the amount of components in the hardener liquid can be increased.

[0045] When the hardener 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 hardener liquid. If the content of gypsum is equal to or more than the lower limit, gelation is promoted, and the initial and final strength of the solidified body is increased. If the content is equal to or less than the upper limit, the viscosity of the main liquid is kept low, which makes it easy to pump the main liquid or the soil stabilization liquid described later to easily penetrate into the ground. If the content is equal to or less than the upper limit, the volume of the solidified body relative to the amount of components in the main liquid can be increased. In addition, when the main liquid material contains gypsum, the hardener liquid does not need to contain gypsum.

[0046] When the hardener liquid according to the present invention contains a water reducing agent, the content of the water reducing agent is preferably 1 to 30 mass %, more preferably 4 to 20 mass %, based on the bentonite.

[0047] (Method of manufacturing hardener liquid) The hardener liquid is produced by dispersing the components other than water in the hardener liquid (hereinafter also referred to as "hardener") in water using a known stirrer, etc. Examples of the dispersion method include a method of dispersing a mixture of hardeners mixed in advance in water, and a method of dispersing hardeners in water in any order.

[0048] There is no restriction on the order in which alumina cement and bentonite are dispersed in water, but in order to suppress bleeding, it is preferable to add and disperse alumina cement after dispersing bentonite in water. By adding alumina cement after the bentonite swells with water, higher viscosity is imparted and bleeding is reduced.

[0049] When the hardeners are mixed in advance, the components of the hardeners may be mixed in the desired amounts using a commonly used mixer. The mixer may be a fixed mixer at the factory or construction site, or a mixer mounted on a mixer truck. It is preferable that each component is thoroughly mixed. By thoroughly mixing each component, a homogeneous hardener liquid can be quickly produced.

[0050] [Soil stabilization chemicals] The soil stabilization liquid of the present invention contains the main liquid and the hardener liquid, and either the main liquid or the hardener liquid contains gypsum, but both the main liquid and the hardener liquid may contain gypsum.

[0051] [Method of manufacturing soil stabilization chemicals] Examples of the method for producing the soil stabilization liquid of the present invention include a method for dispersing each component in water using a known stirrer, a method for adding a component other than water (hardening material) in the hardening liquid to the main liquid, a method for adding a component other than water in the main liquid to the hardening liquid, and a method for mixing the main liquid and the hardening liquid. Among them, the method for producing the soil stabilization liquid is preferably a method for mixing the main liquid and the hardening liquid, from the viewpoint of stabilizing the workability and gel time at the construction site.

[0052] The main liquid and the hardening liquid may be mixed before being injected into the ground, or may be mixed while each liquid is being injected into the ground. When mixing before being injected into the ground, the main liquid and the hardening liquid may be mixed by a general mixing method using a mixer or the like that is usually used when manufacturing cement. When mixing the main liquid and the hardening liquid while being injected into the ground, for example, the main liquid and the hardening liquid may be individually pumped and mixed into a Y-shaped pipe, a mixing device, a mixing chamber (in-pipe mixer / pipe line mixer) provided in the injection pipe using a pump with the same liquid delivery capacity per unit time, or the main liquid and the hardening liquid may be separately pumped through the inner and outer pipes of a double pipe, and the main liquid and the hardening liquid may be mixed by merging them in the ground during injection. In order to prevent the main liquid and the hardening liquid from hardening during injection, it is preferable to produce the soil stabilization liquid immediately before or while being injected, and it is more preferable to produce it while being injected.

[0053] In terms of ease of application, the volume ratio when mixing the main liquid and the hardener liquid is preferably 7:3 to 3:7, more preferably 6:4 to 4:6, and even more preferably an equal volume ratio of 5:5.

[0054] [Ground stabilization method] The ground stabilization method of the present invention has a first embodiment in which the soil stabilization liquid is injected into the ground, and a second embodiment in which the main material liquid and the hardening material liquid are mixed inside the ground. A specific example of the method of the first embodiment is a method in which a soil stabilization chemical is obtained in the same manner as in the above-mentioned method for producing the soil stabilization chemical, and the soil stabilization chemical is injected into the ground. A specific method of the second embodiment is, for example, a method in which the main liquid and the hardening liquid are injected into the ground through separate injection pipes, and the two liquids are allowed to join and mix in the ground. In this embodiment, the injection is performed using an injection pipe having a jet nozzle at a pressure of 50 to 1000 kg / cm. 2 It can also be injected by injection.

[0055] [Effects] According to the present invention, it is possible to provide a soil stabilization liquid that has a small amount of bleeding even when the gel time is extended and can stand on its own in a short time, a manufacturing method for said soil stabilization liquid, and a ground stabilization method. The effects of the present invention are believed to be due to the following mechanism.

[0056] By mixing the hardening agent liquid, which is obtained by the reaction between swollen bentonite and alumina cement and has been prevented from settling, with a main liquid in which inorganic alkali metal carbonate and hydraulic cement have been mixed in advance, settling of the obtained soil stabilization chemical liquid is suppressed. As a result, it is believed that even if the gel time is extended, the amount of bleeding is reduced and the liquid can become self-supporting in a short period of time.

[0057] It is also believed that the action of alumina cement, gypsum, and inorganic alkali metal carbonates accelerates the generation of ettringite and other compounds, promoting hardening and enabling the concrete to become self-supporting in a short period of time.

[0058] In the present invention, the amount of bleeding varies depending on the gel time, and the gel time varies depending on the component composition of the soil stabilization liquid. However, according to the soil stabilization liquid of the present invention, in a soil stabilization liquid having a relatively long gel time, for example, a gel time of 5 to 60 minutes, the amount of bleeding can be kept to 3% or less, preferably 1% or less. The gel time of the soil stabilization solution of the present invention varies depending on the component composition, but can usually be about 5 to 60 minutes. There is no particular lower limit to the bleeding amount.

[0059] Here, the bleeding amount is the ratio (percentage) of the amount (volume) of floating water in the soil stabilization liquid (total of the main liquid and hardener liquid) that remains as the supernatant when the soil stabilization liquid reaches its gel time, to the volume of the soil stabilization liquid (total of the main liquid and hardener liquid), and is measured by the method described in the Examples section below. EXAMPLES

[0060] 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. The materials, methods for preparing the main liquid material and the hardener liquid, and various measurement and evaluation methods used in the following examples and comparative examples are as follows.

[0061] [material] (Main material liquid) Hydraulic cement: Ordinary Portland cement ·Anhydrous sodium carbonate (Na2CO3) Anhydrous potassium carbonate (K2CO3) Gypsum: Type II anhydrous gypsum (Blaine value: 6500 cm 2 / g) Water: Tap water

[0062] (hardening material liquid) Alumina cement: JIS-R2511, type 3 Bentonite (Haruna, manufactured by Hojun Co., Ltd.) Bentonite (Neoclay, manufactured by Hojun Co., Ltd.) · Water reducing agent: Sodium naphthalene sulfonate · Formaldehyde condensate Water: Tap water

[0063] [How to prepare the main liquid] Using materials whose temperature had been adjusted to 20°C, a mixture of anhydrous sodium carbonate or anhydrous potassium carbonate (however, no inorganic alkali metal carbonate was used in Comparative Examples 1 and 3) and gypsum (however, no gypsum was used in Example 4 and Comparative Example 2) was dispersed in water in a room at 20°C, after which ordinary Portland cement was dispersed and stirred to obtain a main liquid. Stirring was carried out for a specified time using a magnetic stirrer with a 4 cm long stir bar placed in a 200 mL disc cup containing 200 mL of main liquid at a rotation speed of 650 to 750 rpm. The content of each component in the main solution is shown in Table 1. In the present embodiment and comparative example, the main liquid material was prepared immediately before the hardener liquid was prepared.

[0064] [How to prepare the hardener liquid] Materials adjusted to 20°C were used, and bentonite and a water-reducing agent were dispersed in water in a room at 20°C. After stirring for 3 minutes, alumina cement (additionally gypsum in Examples 4 and 5, and further anhydrous sodium carbonate in Comparative Example 3) 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 for a specified time using a magnetic stirrer, with a 4 cm long stirrer bar placed in a 200 mL disc cup and 200 mL of hardener liquid placed in it, at a rotation speed of 650 to 750 rpm. The content of each component in the hardener liquid is shown in Table 1.

[0065] [Gel time measurement] 100 mL of the obtained main liquid and 100 mL of the hardener liquid were placed in 200 mL disc cups A and B, respectively, and the entire amount of the main liquid was forcefully poured into disc cup B containing the hardener liquid. The mixture of the two liquids was then immediately transferred to disc cup A, which had contained the main liquid, and then transferred to disc cup B, which had contained the hardener liquid. The cup was tilted every 5 minutes, and the time until the liquid surface did not move even when tilted 45° was recorded as the gel time.

[0066] [Measurement of breathing amount] 100mL of the obtained main liquid and 100mL of the hardener liquid were placed in 200mL disc cups A and B, respectively, and the entire amount of the main liquid was forcefully poured into disc cup B containing the hardener liquid. The mixture of both liquids was then immediately transferred to disc cup A, which had contained the main liquid, and then transferred to disc cup B, which had contained the hardener liquid. After one hour, the water that had risen to the top due to settling was separated into a measuring cylinder, and the amount of bleeding was calculated using the following formula. Amount of bleeding (%) = (amount of water collected (mL) / 200 (mL)) x 100

[0067] [Measurement of the hardness of the liquid after 1 hour] The measurements were carried out using a vane shear tester (torque driver FTD-10CN-S: manufactured by Tohnichi Manufacturing Co., Ltd., vane blade: D15mm x H30mm). 100mL each of the main liquid and hardener liquid were prepared in 200mL disc cups A and B, and the entire amount of the main liquid was forcefully poured into disc cup B containing the hardener liquid, after which the mixture of the two liquids was immediately transferred to disc cup A, which had contained the main liquid, and then transferred to disc cup B, which had contained the hardener liquid, and left to stand. After leaving this mixture to stand for 1 hour, the vane blade was inserted into the center of disc cup B and rotated, and the vane shear strength 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 the vane blade (m) The vane shear strength is 1.2 (kN / m 2 ) or more.

[0068] [Examples 1 to 5 and Comparative Examples 1 to 4] In Examples 1 to 5 and Comparative Examples 1 to 4, the main liquid and hardener liquid prepared as described above with the components and the contents of the components shown in Table 1 were used, and the gel time, bleeding amount, and hardness of the liquid after 1 hour were measured to evaluate each evaluation item. The evaluation results are shown in Table 1. All evaluations were carried out at a temperature of 20°C.

[0069] [Table 1]

[0070] In Examples 1 to 5, in which the soil stabilization liquid of the present invention was used, the amount of bleeding was small even when the gel time was extended to 20 minutes, and the hardness of the liquid became 1.2 (kN / m 2 ) and was able to stand on its own. In particular, Examples 1 and 2, in which sodium carbonate and gypsum were added to the main liquid, had a small amount of bleeding of 1% or less and were able to stand on their own after one hour. Furthermore, in Example 5, in which gypsum was added to both the main liquid and the hardener liquid, the amount of bleeding was small at 1% or less, and the structure was able to stand on its own after one hour and had high strength. On the other hand, in Comparative Example 1, in which a soil stabilization liquid that did not contain inorganic alkali metal carbonate in either the main liquid or the hardening liquid was used, the liquid was soft after one hour and was unable to stand on its own. In Comparative Example 3, in which inorganic alkali metal carbonate was included in the main liquid but not in the hardening liquid, the liquid was hard enough to stand on its own after one hour, but the bleeding amount was poor at 3% or more. In Comparative Example 2, in which a soil stabilization liquid that did not contain gypsum in either the main liquid or the hardening liquid was used, hardening did not progress and the bleeding amount could not be measured. Moreover, in Comparative Example 4, in which the hardener liquid did not contain bentonite, the amount of bleeding was large. [Industrial Applicability]

[0071] The soil stabilization chemical solution, the manufacturing method of said chemical solution, and the ground stabilization method of the present invention are suitably used in the field of reinforcing the ground by injecting the chemical solution into voids in the ground, voids between a revetment embankment and the ground, cavities caused by liquefaction, cavities behind a tunnel, etc., and are therefore extremely useful industrially.

Claims

1. A soil stabilization chemical solution comprising a base liquid containing hydraulic cement, an inorganic alkali metal carbonate, and water, and a hardening liquid containing bentonite, alumina cement, and water, wherein at least one of the base liquid and the hardening liquid contains gypsum.

2. A method for producing a soil stabilization chemical solution, comprising a step of mixing a main liquid containing hydraulic cement, an inorganic alkali metal carbonate, and water with a hardening liquid containing bentonite, alumina cement, and water, wherein at least one of the main liquid and the hardening liquid contains gypsum.

3. A ground stabilization method comprising injecting the soil stabilization solution according to claim 1 into the ground.

4. A ground stabilization method in which a main liquid containing hydraulic cement, an inorganic alkali metal carbonate, and water is mixed in the ground with a hardening liquid containing bentonite, alumina cement, and water, wherein at least one of the main liquid and the hardening liquid contains gypsum.

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