JP2000248279A - Silicate-based chemical for stabilizing soil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a chemical for soil stabilization having excellent development of strength of hardened body obtained in an instant hardening type or a middle hardening to a long hardening type and not causing disproportionation phenomena by precipitation and settling of a silicic acid component in the chemical. SOLUTION: In this chemical for soil stabilizer comprising a main agent solution composed of an aqueous solution of an alkali silicate as a main component and a hardening agent solution composed of an aqueous solution of sulfamic acid as a main component, the total number of mols of Al and Mg contained based on 1 mol of an SiO2 component in the chemical is >=0.005 mol and <0.020 mol, and the hardening agent solution is formulated with >=0.005 mol of the total number of mols of Al and Mg derived from at least one kind of component selected from the group consisting of aluminum sulfate and magnesium (hydroxide)oxide based on 1 mol of the SiO2 component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicate-based soil stabilizing chemical used in a ground stabilization method.

[0002]

2. Description of the Related Art Conventionally, a stabilization method has been known in which various chemicals are injected into the ground in order to strengthen soft ground or stop water from leaking ground and gelate in the ground. So-called silicate-based soil stabilization chemicals, which consist of a chemical liquid in which a base liquid mainly composed of an alkali silicate aqueous solution and a hardening agent are combined, are inexpensive and cause pollution as compared with other soil stabilization chemicals. It is widely used at present because of its low risk.

[0003] This silicate-based soil stabilizing chemical solution is constructed by adjusting the gel time of the chemical solution according to the purpose of construction and the condition of the ground by adjusting the amount of the curing agent used. For example, in the construction by the so-called permeation injection method, in which the chemical solution is sufficiently penetrated into the gap between the soil particles and then gelled,
The gel time of the drug solution is adjusted from several minutes to several tens of minutes before use.

[0004] Also, in the above-mentioned infiltration method, depending on the soil conditions of the ground, the chemical solution may flow out into the ground other than the construction site before gelling yet, making the construction unreliable.
In the case where chemicals may flow into groundwater or well water and cause pollution problems, or when water leakage is stopped, the gel time of the chemicals is adjusted within 10 seconds or less to form a gel, a so-called construction method. Construction is performed by the instantaneous construction method.

[0005] Various substances are currently known as curing agents for silicate-based soil stabilizing chemicals, and are widely used. Among them, sulfamic acid is particularly powdery white having low hygroscopicity and low corrosiveness. As is well known, it is a crystal and exhibits a strong acidity comparable to sulfuric acid when dissolved in water, so that it is useful as a hardener that is easy to handle.

Japanese Patent Application Laid-Open No. 56-1552 discloses a silicate-based soil stabilization chemical solution in which sulfamic acid is used as a curing agent, and an inorganic salt or a metal salt is used in combination therewith.
No. 87, Japanese Patent Application Laid-Open No. 58-29882, Japanese Patent Application Laid-Open
JP-A-8-59281 and JP-A-58-141284.

Japanese Patent Application Laid-Open No. 56-155287 discloses a hardening agent for a water glass based soil stabilizer mainly comprising a mixture of sulfamic acid and a water-soluble inorganic salt in a weight ratio of about 2: 1 to 1: 1. Among the water-soluble inorganic salts, magnesium salts such as aluminum sulfate, magnesium chloride, and magnesium sulfate, and aluminum salts are also disclosed as useful ones. However, in this publication, about 100 parts by weight of a 5 to 15% by weight aqueous solution is mixed with 100 parts by weight of a 30 to 70% aqueous solution of a water glass-based soil stabilizer when using a curing agent. The total number of moles of aluminum and magnesium with respect to SiO ₂ is about 0.12 to 1.7. When aluminum and magnesium are contained in a large amount in this way, S
Precipitation of the iO ₂ component occurs, making it difficult to obtain a uniform cured product.

JP-A-58-29882 discloses a soil treating agent comprising an aqueous solution of an alkali metal salt, sulfamic acid and an inorganic salt of magnesium or calcium. It contains 15 to 50 times, preferably 18 to 35 times water glass. However, even in this case, if the ratio of water glass to magnesium is 50 times or less (magnesium is 0.02 mol or more to water glass), precipitation of the SiO ₂ component occurs, and it is difficult to obtain a uniform cured product.

Japanese Unexamined Patent Publication (Kokai) No. 58-59281 discloses a sodium silicate-based injection material containing sulfamic acid as a main curing agent. One or several kinds of metal salts such as magnesium chloride, magnesium sulfate and aluminum sulfate are disclosed. It is described that an enhancement effect can be obtained by the addition. This enhancer is 0.5-6% based on the total amount of injected material
(Weight / capacity). However, even if magnesium chloride or magnesium sulfate is used as a magnesium source, the strength as intended in the present application cannot be obtained, and when aluminum sulfate is used, the amount used is 0.5 to 6% (weight / volume). And therefore this is also Si
O ₂ components are precipitated, and it is difficult to obtain a uniform cured product.

Japanese Unexamined Patent Publication (Kokai) No. 58-141284 describes a ground improvement material mainly composed of a water glass compound and sulfamic acid. The ground improvement material includes lithium, potassium, sodium, magnesium, calcium, It may contain one or more kinds of salts of metals such as aluminum and iron, and the amount of addition may be one of water glass based compounds.
-15% by weight. However, also in this case, when such a large amount of metal salt is added, precipitation of the SiO ₂ component occurs, and it is difficult to obtain a uniform cured product.

[0011]

The silicate-based soil stabilizing chemical solution is prepared by adjusting the gel time of the chemical solution to a desired gel time according to the purpose of the construction and the condition of the ground by appropriately changing the amount of the curing agent used. However, the above-described silicate-based soil stabilizing chemical solution using sulfamic acid as a curing agent and using an inorganic salt or a metal salt in combination with the curing agent can still be said to have sufficient strength. For example, use a small amount ratio of hardener to alkali silicate, adjust the gel time of the chemical solution so that it is a so-called medium-long type of ten minutes to several tens of minutes, and construct it by infiltration into the ground If you do
When the treated ground is cut, this ground collapses, or the amount of hardener to alkali silicate is increased in order to stop water from leaking ground, and the gel time of the chemical solution is reduced to more than ten seconds. There was a problem that water leakage could not be stopped sufficiently even when the construction method was used. Further, depending on the type and amount of the inorganic salt or metal salt used in combination, when the chemical solution is prepared as described above, the SiO 2 in the chemical solution that forms the main body of the gel body may be used.
There is also a problem that the _two components may precipitate and settle, making it impossible to form a uniform hardened body, making it virtually impossible to use it as a ground stabilizing chemical.

An object of the present invention is to improve the above-mentioned problems in the conventional ground stabilizing chemicals, and to reduce the amount ratio of the hardening agent to the alkali silicate so as to have a gel time of from several tens of minutes to several tens of minutes. Even in the case of the mold, the strength of the cured body formed is also good in the case of the so-called instantaneous setting type in which the gel time is more than ten seconds when the amount ratio of the curing agent to the alkali silicate is increased, and the gel body has Main constituent SiO
It is an object of the present invention to provide a silicate-based soil stabilizing chemical liquid that does not prevent a uniform cured product from being obtained due to precipitation and sedimentation of _two components, and thus does not cause a risk that the ground cannot be stabilized.

[0013]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a base solution mainly composed of an aqueous solution of alkali silicate and a hardener solution mainly composed of an aqueous solution of sulfamic acid are used. In the silicate-based soil stabilizer chemical solution that is combined, an aluminum and / or magnesium compound is added so that the total mole number of aluminum and magnesium becomes a specific molar ratio with respect to 1 mole of the SiO ₂ component in the chemical solution. If blended, the molar ratio of the curing agent to the alkali silicate is surprisingly small, and even when the gel time is set to a medium to long-lasting chemical solution of ten minutes to several tens of minutes, the amount ratio of the curing agent is increased. Te development of strength of the cured product was also formed when the Madokayui type within gel time ten seconds is good, and can not be processed stabilize soil causing the precipitation and sedimentation SiO ₂ component in the chemical solution Found that can avoid the risk of that, we have reached the present invention.

That is, the gist of the present invention is to provide a chemical solution for a silicate-based soil stabilizer comprising a combination of a main solution mainly composed of an aqueous solution of an alkali silicate and a curing agent mainly composed of an aqueous solution of sulfamic acid. The total number of moles of aluminum and magnesium contained is 0.005 mol or more and less than 0.020 mol with respect to 1 mol of the SiO ₂ component therein, and the curing agent liquid contains aluminum sulfate, magnesium hydroxide and magnesium oxide. A silicic acid characterized in that the total mole number of aluminum and magnesium derived from at least one component selected from the group consisting of 0.005 mol or more per 1 mol of SiO ₂ component in the chemical solution. In salt chemicals for soil stabilization.

The alkali silicate as a main component of the silicate-based soil stabilizing solution of the present invention has been conventionally used in silicate-based soil stabilizing solutions, for example, Japanese Industrial Standard (JIS)
No. 1 to 3 sodium silicate specified in K-1408), silica sol having a SiO ₂ / Na ₂ O (molar ratio) in the range of 4 to 100 can be used. "Nitroc" (trade name, manufactured by Mitsubishi Rayon Co., Ltd.) can also be used. These sodium silicates are generally in the form of an aqueous solution, but can be appropriately diluted with water in order to obtain a concentration suitable for stabilizing the soil during construction.

For example, in an ordinary construction method in which an aqueous sodium silicate solution (hereinafter, referred to as solution A) and a hardener solution (hereinafter, referred to as solution B) are mixed in equal volumes and injected into the ground, silicate is used. When JIS No. 3 is used as the soda, usually, 70 to 120 parts by volume of JIS No. 3 water glass diluted with water to 200 parts by volume is used as the liquid A. A
The higher the sodium silicate concentration in the liquid, the greater the strength of the treated ground. On the other hand, if the sodium silicate concentration is too high, the viscosity of the chemical solution will increase, and the equipment load during pumping will increase, and the permeability of the chemical solution in the ground will tend to decrease.

In finding the silicate-based soil stabilizing chemical solution of the present invention, as a measure of the performance of the chemical solution, JIS No. 3 sodium silicate was used as an alkali silicate, and a ratio of JIS No. 3 sodium silicate 80 liters and water 120 liters was used. The aqueous solution prepared by mixing is solution A, and the aqueous solution containing the curing agent is solution B.
A solution obtained by mixing equal amounts of the solution A and the solution B as a solution at a temperature of 20 ° C., (1) adjusting the amount of the curing agent in the solution B to adjust the gel time of the solution to 10 to 30 minutes. When prepared so as to have a medium to long form, the uniaxial compressive strength of the hardened body (homogel body) formed after one day after gelation is 0.10 kgf / cm ² or more,
(2) When the amount of the curing agent in the solution B is adjusted to adjust the gel time of the chemical solution to a so-called instantaneous type within 10 seconds, the cured body formed after one day of gelation (homogel body) ) Uniaxial compressive strength is 0.40kgf / cm
^When the ratio was ² or more, it was determined that the formed cured product exhibited sufficient strength.

Solution B of the silicate-based soil stabilizing chemical solution of the present invention is a solution in which sulfamic acid as a curing agent and the components described below are blended. Sulfamic acid is used to gel the above-mentioned solution A in the ground, and commercially available one can be used. The amount of sulfamic acid used is adjusted according to the desired gel time.
It is often used when shortening the gel time of a chemical solution, and less when increasing the gel time of a chemical solution.

In the present invention, at least one selected from the group consisting of aluminum sulfate, magnesium hydroxide and magnesium oxide is blended in the solution B. This compounding component is SiO ₂ component 1 in a chemical solution obtained by mixing solution A and solution B.
It is blended with the curing agent liquid such that the total number of moles of aluminum and magnesium is 0.005 mol or more and less than 0.020 mol with respect to the mol. If the compounding amount of the compounding component is less than the above range, the strength of the cured product (homogel body) aimed at by the present invention is not obtained, while if the compounding amount is more than the above range, the main body of the gel body is Si in chemical solution
The O ₂ component causes precipitation and sedimentation, so that a uniform cured product cannot be obtained.

The uniaxial compressive strength of the cured product (homogel) intended by the present invention can be obtained only when the above compound specified by the present invention is used as a component to be added to the solution B. For example, aluminum hydroxide, aluminum chloride Although the reason is not clear when blending other than the blending components specified in the present invention, such as magnesium sulfate, magnesium chloride, magnesium phosphate, etc., the uniaxial cured product (homogel body) aimed at by the present invention is not disclosed. Compressive strength cannot be obtained.

When the silicate-based soil stabilizing chemical solution of the present invention is used in a ground stabilization method, a solution containing a main component of an alkali silicate as a main component and water as necessary is used to form a solution A,
Also, a liquid B is prepared by mixing sulfamic acid as a curing agent, a compounding component specified in the present invention, and water, and the prepared liquid A and liquid B are mixed liquids of liquid A and liquid B. The chemical solution obtained by mixing such that the total number of moles of aluminum and magnesium in the mixture becomes the amount ratio specified in the present invention is poured into the ground and hardened to stabilize the ground.

When injecting a drug solution, various injection pipes such as a single pipe type, a double pipe type, and a multiple pipe type can be used.
A method in which the liquid A and the liquid B are preliminarily mixed and led to an injection pipe, a method in which the liquid A and the liquid B are mixed and injected in a mixing section provided at the base of the injection pipe, for example, in a Y-shaped mixing section, An appropriate method can be adopted depending on the gel time and workability of the chemical solution, such as independently leading the solution and the solution B to the injection pipe and joining and mixing in the ground while injecting into the ground from the injection pipe. .

As described above, when the silicate-based soil stabilizing chemical of the present invention is used, the gel time of the chemical is high in the cured product obtained regardless of whether it is a flash-setting type or a medium- to long-setting type. Strength can be imparted, and an unexpected situation in which a uniform hardened body cannot be obtained due to precipitation and sedimentation of the SiO ₂ component in the chemical solution, and ground stabilization processing cannot be performed can also be avoided.

[0024]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited to these examples. Examples and Comparative Examples Solution A: Prepared by adding 120 liters of water to 80 liters of JIS No. 3 sodium silicate. Solution B: Sulfamic acid and various compounding components were prepared by dissolving the amounts shown in Table 1 in water so that the volume became 200 liters. Reagent first class was used for each of the sulfamic acid and various components.

50 liters of each of the solution A and the solution B was mixed at a temperature of 20 ° C. and cured to obtain a homogel body. The type and amount of the ingredients in each test, the amount of sulfamic acid,
The total number of moles of aluminum and magnesium with respect to SiO _{2 in} the mixed solution of the solution A and the solution B (indicated as a molar ratio in the table) and the performance evaluation items of the chemical solution were as follows. In the table, the mixing status is indicated), the gel time of the mixed solution of the solution A and the solution B, and the uniaxial compressive strength of the cured body (homogel body) formed one day after curing, and the overall evaluation. Table 1 and Table 2
It was shown to.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

In the columns of the types of components in the table, C: aluminum sulfate, D: magnesium hydroxide, E: magnesium oxide, F: magnesium sulfate heptahydrate, G: magnesium chloride, H: aluminum hydroxide, J: chloride Aluminum, K: indicates magnesium phosphate. The amount of the compounding component indicates the amount (kg) of the compounding component or sulfamic acid contained in 200 liters of the liquid B.

The test methods and evaluation criteria for each evaluation item of the chemical solution performance are as follows. Situation at the time of mixing the liquid A and the liquid B: At a liquid temperature of 20 ° C., equal amounts of the liquid A and the liquid B were mixed well, allowed to stand in a container, and the state of the mixed liquid was visually observed. ○ in the same column indicates precipitation of silicic acid component
No sedimentation, uniform gel body was formed, ×
Indicates that the silicic acid component was precipitated and precipitated, and a uniform gel was not formed.

Gel time of chemical solution: A solution of solution A and solution B of equal volume were well mixed at a liquid temperature of 20 ° C. and allowed to stand in a container. The time required for the mixed solution to lose its fluidity was defined as gel time. Uniaxial compressive strength of cured product: Liquid A and liquid B at liquid temperature of 20 ° C
A mixture of equal volumes of the liquids is placed in a cylindrical mold (diameter 5 cm x height 10 c).
m), and the uniaxial compressive strength of the hardened material thus formed was measured for one day of material age. -Indicates that the uniaxial compressive strength was not measured because a uniform gel body was not formed.

Comprehensive evaluation: When the mixing status is ○ and the gel time is 10 to 30 minutes, the measured uniaxial compressive strength is 0.10 kgf / cm ² or more and the gel time is 1
In the case of 0 seconds or less, the uniaxial compressive strength is 0.40 kgf / cm
^{If the value is 2} or more, the result is indicated by ○, and the mixing status is indicated by ×,
When the uniaxial compressive strength did not reach the above criteria, it was evaluated as x.

As is clear from the table, when the requirements of the present invention are satisfied, a uniform gel body is formed without precipitation and precipitation of the silicate component even when the solution A and the solution B are mixed, and a gel time of 1 is obtained.
In the case of the medium to long sintering type for 0 to 30 minutes, the uniaxial compressive strength of the formed hardened body (homogel body) per day is 0.10.
In the case of the instantaneous setting type of not less than kgf / cm ^{2 and} the gel time of less than 10 seconds, the uniaxial compressive strength of the hardened material per day is 0.4%.
0 kgf / cm ² or more, satisfying the performance standard of the chemical solution, and achieving the object of the present invention. On the other hand, even when the compounding component specified in the present invention is used, the molar ratio of aluminum and magnesium to the silicate component is increased. If deviated from the provisions of the present invention, or even a salt of aluminum or magnesium, when using other than the components specified in the present application, precipitation or precipitation of the silicate component, or obtained cured product , The uniaxial compressive strength is low, and the object of the present invention cannot be achieved.

[0034]

According to the silicate soil stabilizing chemical solution of the present invention and the ground stabilization method using the same, a conventional sulphamic acid is used as a hardening agent, and an inorganic salt or a metal salt is used in combination with the hardening agent. No performance, i.e., even if the gel time of the chemical solution is a flash-setting type or a medium- to long-setting type, the obtained cured product exhibits good strength development, and the silicate component in the chemical solution is precipitated.・ Because there is no sedimentation, the obtained hardened material does not become uneven, and it is possible to avoid the unexpected situation that the ground cannot be stabilized and has the feature that the ground can be stabilized more securely and reliably. .

Claims (1)

[Claims] 1. A silicate-based soil stabilizer chemical liquid comprising a combination of a base liquid mainly composed of an aqueous alkali silicate solution and a hardener liquid mainly composed of an aqueous solution of sulfamic acid,
The total number of moles of aluminum and magnesium contained is 0.005 mol or more and less than 0.020 mol per 1 mol of the SiO ₂ component in the chemical solution, and the curing agent liquid contains aluminum sulfate, magnesium hydroxide and magnesium oxide. Wherein the total mole number of aluminum and magnesium derived from at least one component selected from the group consisting of is at least 0.005 mole per mole of SiO ₂ component in the chemical solution. Silicate soil stabilization chemical.