Soil stabilization chemicals, manufacturing method thereof, and ground stabilization method

Abstract

To provide a liquid chemical for soil stabilization which reduces the influence of the fluctuation of the amount of citric acid (organic carboxylic acid and / or its salt) on gel time and has a small bleeding amount, a method for producing the chemical liquid, and a ground stabilization method.SOLUTION: A liquid chemical for soil stabilization of the invention comprises a main material liquid containing lime, organic carboxylic acid and / or its salt, hydraulic cement and water, and a hardening material liquid containing amorphous aluminum hydroxide, alkali metal carbonate and water. The main material liquid preferably contains a high-performance water reducing agent as a water reducing agent.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Cement suspensions, in which cement is suspended in water, are used as soil stabilization liquids that are injected into the ground to reinforce it. However, cement suspensions have a slow setting speed and take several hours to set, during which time the cement settles and does not harden completely.

[0003] Furthermore, when a cement suspension is injected into the ground to be used as a soil stabilization liquid, it may be required that the fluidity be maintained before injection into the ground and until it reaches a designated location, and that the fluidity be lost after it reaches the designated location.

[0004] Recently, therefore, materials that are given the function of making the cement suspension non-fluid within a specified period of time have come into use. For example, Patent Document 1 discloses a two-shot type injection material made by mixing Liquid A, which contains hydrated lime or quicklime, with Liquid B, which contains dried aluminum sludge powder (aluminum sludge generated during anodizing is dried and aluminum hydroxide is kept amorphous). Patent Document 1 reports an example in which the time it takes for Liquid A and Liquid B to gel after mixing is complete (the time it takes for the liquid to become non-fluid; hereinafter referred to as "gel time") is about 60 seconds. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2010-53023 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the injection material of Patent Document 1, the amount of citric acid used as the organic carboxylic acid and / or its salt (hereinafter also referred to as organic carboxylic acid (salt)) has a large effect on the gel time, and there is concern that the variation in the amount of citric acid will lead to variation in the gel time. In addition, the injection material of Patent Document 1 has a large amount of supernatant water after gelation (hereinafter referred to as bleeding amount), which may cause voids when filling a cavity, etc.

[0007] Therefore, the present invention aims to provide a soil stabilization chemical solution with little variation in gel time due to variation in the amount of organic carboxylic acid (salt), a method for producing said chemical solution, and a ground stabilization method. Another object of the present invention is to provide a soil stabilization chemical solution with little bleeding, a method for producing said chemical solution, and a ground stabilization method. [Means for solving the problem]

[0008] The present invention includes the following aspects [1] to

[12] .

[0009] [1] A soil stabilization liquid comprising a base liquid containing lime, an organic carboxylic acid and / or its salt, a water reducing agent, and water, and a hardening liquid containing amorphous aluminum hydroxide, an alkali metal carbonate, and water. [2] The soil stabilization solution according to [1], in which the bleeding amount is 2% or less when the gel time is less than 60 seconds. [3] A soil stabilization chemical solution according to [1] or [2], in which the bleeding amount is 4% or less when the gel time is 60 seconds or more and less than 100 seconds. [4] The soil stabilization chemical liquid according to any one of [1] to [3], wherein the main liquid further contains hydraulic cement and gypsum. [5] The soil stabilization chemical solution according to any one of [1] to [4], wherein the water reducing agent contains, as a main component, at least one selected from the group consisting of naphthalene sulfonate-formaldehyde condensates, lignin sulfonates or derivatives thereof, melamine-formaldehyde condensates, polycarboxylic acids, aminosulfonic acids, and polyethers. [6] The soil stabilization chemical solution according to any one of [1] to [5], wherein the water reducing agent is contained in an amount of 0.1% by mass to 20% by mass relative to the lime. [7] The soil stabilization chemical solution according to any one of [1] to [6], wherein the organic carboxylic acid and / or its salt is contained in an amount of 0.2% by mass to 20% by mass relative to the lime. [8] A ground stabilization method comprising injecting a soil stabilization chemical solution described in any one of [1] to [7] into the ground. [9] A method for producing a soil stabilization liquid, comprising the step of mixing a main liquid containing lime, an organic carboxylic acid and / or its salt, a water reducing agent, and water with a hardening liquid containing amorphous aluminum hydroxide, an alkali metal carbonate, and water.

[10] The method for producing a soil stabilization liquid described in [9], wherein the main liquid further contains hydraulic cement and gypsum.

[11] A ground stabilization method in which a base liquid containing lime, organic carboxylic acid and / or its salt, water reducing agent, and water is mixed in the ground with a hardening liquid containing amorphous aluminum hydroxide, alkali metal carbonate, and water.

[12] The ground stabilization method described in

[11] , wherein the main liquid further contains hydraulic cement and gypsum. Effect of the Invention

[0010] According to the present invention, it is possible to provide a soil stabilization chemical solution with little variation in gel time due to variation in the amount of organic carboxylic acid (salt), a method for producing the chemical solution, and a ground stabilization method. Also, according to the present invention, it is possible to provide a soil stabilization chemical solution with little bleeding, a method for producing the chemical solution, and a ground stabilization method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described in detail below.

[0012] [Main liquid] The main liquid according to one embodiment of the present invention (hereinafter also referred to as "main liquid") contains lime, an organic carboxylic acid and / or its salt, a water reducing agent, and water. The main liquid may further contain hydraulic cement and gypsum. The main liquid may also contain other additives. Each component contained in the main liquid material will be described below.

[0013] (plaster) 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.

[0014] The Blaine value of gypsum is 1500 to 12000 cm 2 / g is preferred, and 2000 to 10000 cm 2 / g is more preferable, and 2500 to 8000 cm 2 If the Blaine value of the gypsum is equal to or higher 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 lower than the upper limit, the viscosity of the main liquid material will be reduced and aggregation will be 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.

[0015] The content of gypsum in the main liquid is preferably 1 to 30 kg, and more preferably 3 to 20 kg, per 200 L of main liquid (total liquid: 400 L). If the content of gypsum is equal to or greater than the lower limit, the initial and final strength of the solidified body will be high. If the content is equal to or less than the upper limit, the viscosity of the main liquid will be suppressed, making it easier to pump the liquid, and the main liquid or the soil stabilization liquid described below will more easily 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.

[0016] (lime) Lime takes the form of calcium hydroxide (Ca(OH)2) in water, and examples include slaked lime (Ca(OH)2) and quicklime (CaO). Among these, slaked lime is preferred because it is easy to handle.

[0017] The Blaine value of lime is 6000~30000 cm 2 / g is preferable, and 8000 to 20000 cm 2 If the Blaine value of lime is equal to or greater than the lower limit, the base liquid is less likely to settle and has a high reactivity. On the other hand, if the Blaine value is equal to or less than the upper limit, the viscosity of the base liquid is reduced and aggregation is less likely to occur when mixed with water. The lime may be contained in a single type or in a combination of two or more types.

[0018] The content of lime in the main liquid is preferably 5 to 50 kg, and more preferably 7 to 30 kg, per 200 L of main liquid (total liquid: 400 L). If the content of lime is equal to or greater than the lower limit, the initial strength after gelation will rise quickly. If the content is equal to or less than the upper limit, the viscosity of the main liquid will be suppressed, making it easier to pump the main liquid or the soil stabilization liquid described below more 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.

[0019] (Organic carboxylic acid and / or its salt) Examples of organic carboxylic acids (salts) 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, as well as alkali metal salts (lithium salt, sodium salt, potassium salt, etc.) and ammonium salts of these oxycarboxylic acids. Examples of aminocarboxylic acids include glutamic acid, as well as alkali metal salts (lithium salt, sodium salt, potassium salt, etc.) and ammonium salts of these aminocarboxylic acids. Among these, oxycarboxylic acids and / or their salts are 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 particularly preferred.

[0020] These organic carboxylic acids (salts) may be used alone or in combination of two or more kinds.

[0021] The content of the organic carboxylic acid (salt) in the soil stabilization chemical solution of the present invention varies depending on the desired gel time, but is preferably 0.2% by mass to 20% by mass relative to the lime, more preferably 0.3% by mass to 10% by mass, and particularly preferably 0.5% by mass to 8% by mass. If the content of the organic carboxylic acid (salt) in the soil stabilization chemical solution is equal to or higher than the lower limit, it is easy to obtain the effect of adjusting the gel time and improving the initial rise strength of gelation by containing the organic carboxylic acid (salt). On the other hand, if the content of organic carboxylic acid (salt) in the soil stabilization liquid is below the above upper limit, it is easy to adjust the gel time and improve the initial strength buildup at the beginning of gelation, and delays in strength buildup after several hours or days rather than at the beginning of gelation are less likely to occur.

[0022] (Water reducing agent) As the water-reducing agent, it is preferable to use a high-performance water-reducing agent with excellent water-reducing performance, and examples thereof include water-reducing agents mainly composed of naphthalene sulfonate-formaldehyde condensate, lignin sulfonate or its derivatives, melamine formalin condensate (sulfonate, (modified) methylol), polycarboxylic acid, aminosulfonic acid, and polyether. Here, the "main component" refers to a component that usually accounts for 50% by mass or more of the total, preferably 70% by mass or more, and more preferably 90% to 100% by mass. These water reducing agents may be used alone or in combination of two or more. Of the water-reducing agents used in the present invention, naphthalene sulfonate-formaldehyde condensate-based materials are preferred.

[0023] The content of the water reducing agent in the soil stabilization chemical solution of the present invention is preferably 0.1% by mass to 20% by mass, more preferably 0.2% by mass to 10% by mass, and particularly preferably 0.5% by mass to 5% by mass, based on the lime. If the content of the water reducing agent in the soil stabilization chemical solution is equal to or higher than the lower limit, the effect of the variation in the amount of organic carboxylic acid (salt) on the gel time can be reduced, and the amount of bleeding can be reduced. On the other hand, if the content of the water reducing agent in the soil stabilization chemical solution is equal to or lower than the upper limit, the settling of cement and the like in the main material due to the viscosity of the main material liquid being too low can be suppressed.

[0024] (hydraulic cement) Examples of 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, granulated blast furnace slag, and alumina cement. Hydraulic cement also includes pozzolanic reactive substances, which exhibit hydraulic properties due to the presence of lime. Examples of such pozzolanic reactive substances include silica fume, fly ash, and activated kaolin. The hydraulic cement may be contained in a single type or in a combination of two or more types.

[0025] When the main liquid contains hydraulic cement, the content of hydraulic cement in the main liquid is preferably 25 to 300 kg, more preferably 50 to 200 kg, and particularly preferably 70 to 150 kg per 200 L of main liquid (total liquid: 400 L). 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 easily 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.

[0026] (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.

[0027] (Additives) The main liquid may contain additives such as a defoamer and a thickener.

[0028] Examples of the defoaming agent include higher alcohol-based, alkylphenol-based, diethylene glycol-based, dibutyl phthalate-based, water-insoluble alcohol-based, tributyl phosphate-based, polyglycol-based, silicone-based, and ethylene oxide-propylene oxide copolymer-based defoaming agents.

[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.

[0030] The main liquid may also contain sulfates such as sodium sulfate, potassium sulfate, and aluminum sulfate as a sulfate ion source.

[0031] (Method of manufacturing the main liquid) The main liquid material is prepared by dispersing the components in desired amounts in water using a known stirrer or the like. The order of mixing the lime, organic carboxylic acid (salt), water reducing agent, water, hydraulic cement used as needed, gypsum, and other additives when producing the main liquid material is not particularly limited. The method of producing the main liquid material is preferably a method in which the lime, organic carboxylic acid (salt), water reducing agent, gypsum as an optional component, thickener, antifoaming agent, and other additives are dispersed in water, then hydraulic cement is added, and the mixture is stirred for a predetermined time to mix.

[0032] Examples of methods for producing the main liquid material at a construction site where ground stabilization is performed include the following methods (1) to (3). (1) A method in which lime, organic carboxylic acid (salt), water-reducing agent, gypsum (if necessary), and hydraulic cement are brought separately to the construction site, mixed in the prescribed ratio, and then water is added and mixed. (2) A method in which a mixture of lime, organic carboxylic acid (salt), water-reducing agent, gypsum (if necessary), and hydraulic cement is mixed in a predetermined ratio as the main material, is brought to the construction site, and water is added and mixed. (3) A method in which materials other than hydraulic cement are mixed in a predetermined ratio and then brought to the construction site together with the hydraulic cement, and water is added and mixed. Among these, the above methods (2) and (3) are preferred because they simplify the work at the construction site.

[0033] It is preferable that each component is sufficiently dispersed in water, so that the main liquid and the hardener liquid are mixed more uniformly, the gel time is stable, and the variation in the compressive strength of the solidified body is reduced.

[0034] [Curing material liquid] A hardener liquid according to one embodiment of the present invention (hereinafter also referred to as a "hardener liquid") is used by being mixed into a main liquid material in order to harden the main liquid material. The hardener liquid contains amorphous aluminum hydroxide, an alkali metal carbonate, and water. The hardener liquid may contain other additives in addition to those mentioned above. Each component contained in the hardener liquid will be described below. In the following, the components in the hardener liquid other than water will be referred to as the hardener.

[0035] (Amorphous Aluminum Hydroxide) In the present invention, the amorphous aluminum hydroxide includes all amorphous aluminum hydroxides. Examples of amorphous aluminum hydroxide include dried aluminum hydroxide gel, aluminum sludge generated in anodizing, etc. Among these, dry aluminum hydroxide gel is preferred from the viewpoint of high activity.

[0036] Dry aluminum hydroxide gel is a compound with the chemical composition Al(OH)3·mH2O, and is amorphous aluminum hydroxide. Examples of dry aluminum hydroxide gel include those used in medical antacids and ulcer healing agents in the Japanese Pharmacopoeia, but for industrial use, dry aluminum hydroxide gel powder used as an adsorbent is preferred. The aluminum oxide content of the dry aluminum hydroxide gel powder is preferably 45% or more, more preferably 50% or more. The particle size of the dry aluminum hydroxide gel powder is preferably 40 to 120 μm, more preferably 60 to 100 μm, as determined by a laser diffraction scattering method. If the median size is equal to or greater than the lower limit, the particles are less likely to fly around, improving the ease of handling. On the other hand, if the median size is equal to or less than the upper limit, the particles are prevented from settling, and the reactivity is increased, resulting in excellent gel time expression.

[0037] (alkali metal carbonate) The alkali metal carbonate is a component that adds gel time to the combination of lime, which has gelling ability, and amorphous aluminum hydroxide. When the alkali metal carbonate is mixed with the main liquid, it makes the main liquid unstable, but when it is mixed with the hardener liquid, it does not make the hardener liquid unstable.

[0038] Examples of the alkali metal carbonate include carbonates of alkali metals such as Li2CO3, Na2CO3, K2CO3, etc. Only one type of alkali metal carbonate may be contained, or two or more types may be contained in combination.

[0039] (Additives) The hardener liquid may contain various additives such as alkali metal hydroxide, alkali metal silicate, antifoaming agent, thickener, etc., in addition to amorphous aluminum hydroxide (including dried aluminum hydroxide gel) and alkali metal carbonate. Details of the other additives are the same as those of the additives contained in the main liquid.

[0040] For example, the activity of the hardener liquid can be increased by adding an alkali metal hydroxide to the hardener liquid. Examples of the alkali metal hydroxide include LiOH, NaOH, KOH, etc. Only one type of alkali metal hydroxide may be contained, or two or more types may be contained in combination.

[0041] Similarly, the activity of the hardener liquid can be increased by adding an alkali metal silicate to the hardener liquid. Examples of the alkali metal silicate include lithium silicate, sodium silicate, and potassium silicate. Only one type of alkali metal silicate may be contained, or two or more types may be contained in combination.

[0042] Examples of alkali metal silicates include aqueous solutions, granular products, and powder products of alkali metal orthosilicates, alkali metal sesquisilicates, alkali metal metasilicates, alkali metal silicates No. 1, alkali metal silicates No. 2, alkali metal silicates No. 3, and alkali metal silicates No. 4. Among these, alkali metal orthosilicates with high alkalinity are preferred from the viewpoint of their high effect of increasing reactivity, and sodium orthosilicate is more preferred.

[0043] (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.

[0044] (Content of each component in the hardener liquid) The content of amorphous aluminum hydroxide (including dry aluminum hydroxide gel) in the hardener liquid is preferably 2 to 20 kg per 200 L of the hardener liquid (total liquid 400 L), more preferably 4 to 12 kg, and particularly preferably 6 to 8 kg. If the content of amorphous aluminum hydroxide (including dry aluminum hydroxide gel) is equal to or greater than the lower limit, the gel time is shortened, and the time required for strength development after gelation is shortened. 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 is easily permeated into the ground.

[0045] The content of the alkali metal carbonate in the hardener liquid is preferably 2 to 12 kg per 200 L of the hardener liquid (total chemical liquid 400 L), more preferably 3 to 10 kg, and even more preferably 4 to 8 kg. If the content of the alkali metal carbonate is within the above range, the gel time can be further shortened. In order to further exert the effects of the present invention, it is preferable that no insoluble portion of the alkali metal carbonate remains when preparing the hardener liquid from the hardener as described later.

[0046] (Method of manufacturing hardener liquid) The hardener liquid may be prepared by preparing each of the raw materials (hardeners) individually and adding them to water on-site to mix, or may be mixed in advance in powder form and added to water on-site to use. Preferably, the amorphous aluminum hydroxide (including dried aluminum hydroxide gel) and the alkali metal carbonate are mixed in powder form beforehand. By mixing them in advance, it is possible to prevent the alkali metal carbonate from caking.

[0047] The powders are mixed by adding the desired amounts of each component to a general mixer. The mixer may be fixed at the factory or construction site, or may be 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.

[0048] The hardener liquid is produced by dispersing each component of the hardener in water using a known stirrer, etc. The dispersion method may be a method of dispersing a previously produced hardener in water, or a method of dispersing each component of the hardener in water in any order.

[0049] It is preferable that each component is sufficiently dispersed in water, 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.

[0050] [Soil stabilization chemicals] A soil stabilization liquid according to one embodiment of the present invention (hereinafter, also referred to as a "soil stabilization liquid") includes a main material liquid and a hardening material liquid. For example, the soil stabilization liquid includes gypsum, lime, an organic carboxylic acid (salt), hydraulic cement, a water reducing agent, water, an amorphous aluminum hydroxide gel, and an alkali metal carbonate.

[0051] [Method of manufacturing soil stabilization chemicals] The method for producing the soil stabilization liquid may be a method of dispersing each component in water using a known stirrer, a method of adding each component in the hardener liquid other than water to the main liquid, a method of adding a component in the main liquid other than water to the hardener liquid, or a method of mixing the main liquid and the hardener liquid. Among them, the method for producing the soil stabilization liquid is preferably a method of mixing the main liquid and the hardener liquid, because the main liquid and the hardener liquid are instantly and uniformly mixed, the work at the construction site can be simplified, and the gel time can be further enhanced.

[0052] A method for mixing the main liquid material and the hardener liquid will be described below. The mixing of both liquids may be performed before injection into the ground, or may be performed while each liquid is being injected into the ground. When mixing is performed before injection into the ground, it is sufficient to mix by a general mixing method using a mixer or the like that is usually used when producing cement. When mixing each liquid while injecting into the ground, for example, the main material liquid and the hardening material liquid are 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 pumps with the same liquid delivery capacity per unit time, or the main material liquid and the hardening material liquid are separately delivered through the inner and outer pipes of a double pipe, and the main material liquid and the hardening material liquid are mixed by merging them in the ground during injection. In order to prevent both liquids from hardening during injection, it is preferable to produce the soil stabilization liquid immediately before injection or while injecting, and it is more preferable to produce it while injecting.

[0053] For ease of application, the main liquid and the hardener liquid are preferably mixed in a volume ratio of 7:3 to 3:7, more preferably 6:4 to 4:6, and particularly preferably mixed in equal volumes.

[0054] [Ground stabilization method] The ground stabilization method of the present invention includes a first embodiment in which the above-mentioned soil stabilization chemical 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 method of the first embodiment is a method in which a soil stabilization chemical is produced in the same manner as the above-mentioned method for producing a soil stabilization chemical, and the soil stabilization chemical is injected into the ground. A specific method of the second embodiment is 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 merged and mixed 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 Alternatively, the mixture may be injected by injection.

[0055] [Effects] According to the present invention, when an organic carboxylic acid (salt) is used to adjust the gel time, a water reducing agent is used in combination, which reduces the effect of fluctuations in the amount of organic carboxylic acid (salt) on the gel time and provides a soil stabilization chemical solution with a low bleeding amount, a method for producing the soil stabilization chemical solution, and a ground stabilization method. Since the amount of organic carboxylic acid (salt) added is very small compared to the amount of the chemical solution, even a slight change in the amount can cause a large change in the gel time, which leads to variations in the gel time. By using the soil stabilization chemical solution of the present invention, a more stable gel time can be ensured. In addition, by reducing the amount of bleeding, it is possible to reduce voids when filling a cavity, for example.

[0056] <Mechanism of the inhibitory effect on the fluctuation of the amount of organic carboxylic acid (salt)> In the present invention, it is believed that the gel time is mainly imparted by the reaction of the lime contained in the main liquid with the amorphous aluminum hydroxide and alkali metal carbonate contained in the hardener liquid. It is also believed that the gel time is delayed by adding an organic carboxylic acid (salt) to the main liquid, since the organic carboxylic acid (salt) is adsorbed on the surface of the lime particles and inhibits the reaction with the hardener liquid. However, when lime particles are dispersed in water, they are not finely dispersed, and the surface area involved in providing gel time is small. Therefore, the surface area that organic carboxylic acids (salts) can adsorb and inhibit is small, and even slight fluctuations in the amount have a large effect on the reaction with the hardener liquid. Here, adding a water reducing agent improves the dispersibility of lime in water, so it acts with a large surface area of ​​lime, and it is thought that the effect of fluctuations in the amount is small.

[0057] <Mechanism for reducing bleeding> It is believed that adding a water-reducing agent to the main liquid improves the dispersibility of lime in water, making it easier for gel to form in fine particles. As a result, it is assumed that the gelation proceeds in a state where the particles are more likely to float, suppressing sedimentation and reducing the amount of bleeding.

[0058] [Breathing amount] The soil stabilization liquid of the present invention can reduce the amount of bleeding by the above-mentioned mechanism. 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, for example, in the case of a soil stabilization liquid having a relatively short gel time of less than 60 seconds, the amount of bleeding can be reduced to 2% or less, preferably 1.5% or less. Also, for example, in the case of a soil stabilization liquid having a gel time of 60 seconds or more but less than 100 seconds, the amount of bleeding can be reduced to 4% or less, preferably 3% 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 30 to 600 seconds. 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: Blast-furnace cement type B (Taiheiyo Cement Corporation) Gypsum: Natural anhydrous gypsum (Blaine value: 3100 cm 2 / g) Lime: Slaked lime (Blaine value: 12000 cm 2 / g) Water reducing agent 1 (high performance water reducing agent): Sodium naphthalenesulfonate-formaldehyde polycondensate Water reducing agent 2 (high performance water reducing agent): Melamine formalin condensate (modified methylol melamine condensate) Organic carboxylic acid: anhydrous citric acid Water: Tap water

[0062] (hardening material liquid) ·Dry aluminum hydroxide gel powder (median diameter: 84 μm) ·Soda ash (anhydrous sodium carbonate) Water: Tap water

[0063] [How to prepare the main liquid] Using materials adjusted to 20℃, a mixture of gypsum, lime, water-reducing agent, organic carboxylic acid, and water-reducing agent was dispersed in water in a room at 20℃, after which hydraulic cement was dispersed and stirred to obtain the main liquid. Stirring was carried out using a magnetic stirrer, with a 4cm-long stir bar placed in a 200mL disc cup containing 200mL of main liquid, at a rotation speed of 650-750rpm. The content of each component in the main liquid is as shown in Table 1. In the present embodiment and comparative example, the hardener liquid was prepared immediately after the main liquid was prepared, and the experiment was carried out.

[0064] [How to prepare the hardener liquid] Using materials adjusted to 20°C, the hardener, which was a mixture of dried aluminum hydroxide gel powder and inorganic alkali metal carbonate, was dispersed in water in a room at 20°C and stirred to obtain a hardener liquid. Stirring was performed using a magnetic stirrer, with a 4 cm long stir 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 as shown in Table 1.

[0065] [Gel time measurement] First, 50 mL of the obtained main liquid and 50 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. After that, 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 two more transfers were performed. Finally, the disc cup into which the liquid had been transferred was held horizontally and the state of the surface was checked. The disc cup was then tilted 45 degrees to check whether the surface of the mixed liquid moved, and the time until the surface of the mixed liquid stopped moving was confirmed.

[0066] [Measurement of breathing amount] After measuring the gel time, the floating water in the drug solution was taken with a dropper and transferred to a measuring cylinder, and the amount was measured and calculated using the following formula. Breathing amount (%) = floating water amount (mL) / (main material liquid 50mL + hardening material liquid 50mL) × 100

[0067] [Measurement of strength after 10 minutes] Compressive strength was measured using a Tensilon universal testing machine. 100mL of the main liquid and 100mL of the hardener liquid, prepared in the same way as for gel time measurement, were mixed and poured into a formwork measuring φ5cm x height 10cm. The mixture was demolded about 8 minutes after mixing, and loading was started at 1mm / min. 10 minutes after mixing, and the peak strength was recorded. The strength was calculated by measuring the loading area of ​​the cylinder.

[0068] [Examples 1 to 7 and Comparative Examples 1 to 5] In Examples 1 to 7 and Comparative Examples 1 to 5, the gel time, some bleeding amounts, and some strengths after 10 minutes were measured using the main liquid and hardener liquid prepared as described above with the components and the contents of the components shown in Table 1. The results are shown in Table 1.

[0069] [Table 1]

[0070] Comparing Example 2 with Comparative Example 1 and Comparative Example 5, it was confirmed that even with the same gel time of 50 seconds, the strength after 10 minutes increases by increasing the amount of lime and adding an organic carboxylic acid (salt), or by adding an organic carboxylic acid (salt) and a water-reducing agent. From a comparison between Examples 1 to 4 and Comparative Examples 1 to 4, it was confirmed that when a water reducing agent was added to the main liquid, the change in gel time was small even if the amount of organic carboxylic acid (salt) changed. In addition, the amount of bleeding increases as the gel time becomes longer since it is caused by the settling of hydraulic cement, etc.; however, when comparing at the same gel time, in Comparative Example 1 which does not contain a water-reducing agent and has a gel time of 50 seconds, the amount of bleeding is 3%, whereas in Examples 1 to 3 which contain a water-reducing agent and have a gel time of about 50 seconds, the amount of bleeding is reduced to 1%. [Industrial Applicability]

[0071] The soil stabilization chemical solution, the manufacturing method of the chemical solution, and the ground stabilization method of the present invention are useful for reinforcing the ground by injecting the chemical solution into, for example, voids in the ground, voids between a revetment embankment and the ground, cavities caused by liquefaction, and cavities behind a tunnel.

Claims

1. A chemical solution for soil stabilization, comprising a base liquid containing hydraulic cement, lime, an organic carboxylic acid and / or its salt, a water reducer, gypsum, and water, and a hardening liquid containing amorphous aluminum hydroxide, an alkali metal carbonate, and water, The gel time when the main liquid and the hardener liquid are mixed is 30 to 600 seconds; The lime content is 7 to 30 kg per 400 L of the total chemical solution, The water reducing agent is contained in an amount of 0.2% by mass to 10% by mass relative to the lime, The organic carboxylic acid and / or salt thereof is contained in an amount of 0.3% by mass to 10% by mass relative to the lime, The content of the amorphous aluminum hydroxide is 2 to 20 kg per 400 L of the total solution, The content of the alkali metal carbonate is 2 to 12 kg per 400 L of the total chemical solution, The volume ratio of the main liquid to the hardening liquid is 7:3 to 3:

7.

2. 2. The soil stabilization chemical according to claim 1, wherein the bleeding amount is 2% or less when the gel time is less than 60 seconds.

3. 3. The soil stabilization chemical solution according to claim 1, wherein the bleeding amount is 4% or less when the gel time is 60 seconds or more and less than 100 seconds.

4. The water reducing agent comprises at least one selected from the group consisting of naphthalene sulfonate-formaldehyde condensate, lignin sulfonate or its derivatives, melamine-formaldehyde condensate, polycarboxylic acid, aminosulfonic acid, and polyether as a main component. The chemical solution for soil stabilization according to any one of claims 1 to 3.

5. A ground stabilization method comprising injecting the soil stabilization chemical solution according to any one of claims 1 to 4 into the ground.

6. A method for producing a chemical solution for soil stabilization, comprising the step of mixing a main liquid containing hydraulic cement, lime, an organic carboxylic acid and / or its salt, a water reducer, gypsum, and water with a hardening liquid containing amorphous aluminum hydroxide, an alkali metal carbonate, and water, The gel time when the main liquid and the hardener liquid are mixed is 30 to 600 seconds; The lime content is 7 to 30 kg per 400 L of the total chemical solution, The water reducing agent is contained in an amount of 0.2% by mass to 10% by mass relative to the lime, The organic carboxylic acid and / or salt thereof is contained in an amount of 0.3% by mass to 10% by mass relative to the lime, The content of the amorphous aluminum hydroxide is 2 to 20 kg per 400 L of the total solution, The content of the alkali metal carbonate is 2 to 12 kg per 400 L of the total chemical solution, A method for producing a soil stabilization chemical liquid, the method comprising producing a soil stabilization chemical liquid having a volume ratio of the main material liquid to the hardening material liquid of 7:3 to 3:

7.

7. A ground stabilization method comprising mixing a main liquid material containing hydraulic cement, lime, an organic carboxylic acid and / or its salt, a water reducer, gypsum, and water with a hardening liquid material containing amorphous aluminum hydroxide, an alkali metal carbonate, and water in the ground, The gel time when the main liquid and the hardener liquid are mixed is 30 to 600 seconds; The amount of lime is 7 to 30 kg per 400 L of the main liquid and hardener liquid in total, The water reducing agent is 0.2% by mass to 10% by mass relative to the lime, The organic carboxylic acid and / or its salt is 0.3% by mass to 10% by mass relative to the lime, The content of the amorphous aluminum hydroxide is 2 to 20 kg per 400 L of the total solution, The content of the alkali metal carbonate is 2 to 12 kg per 400 L of the total chemical solution, A ground stabilization method in which the main liquid and the hardening liquid are mixed so that the volume ratio of the main liquid to the hardening liquid is 7:3 to 3:7.

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