JP2002088365A - Bicarbonate-based hardening agent for silicate-based soil stabilizing chemical liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a bicarbonate-based hardening agent for a silicate-based soil stabilizing chemical liquid resistant to caking after the storage for a long period, having high solubility in water and developing high strength of the hardened material. SOLUTION: The hardening agent is composed of (a) sodium bicarbonate, (b) potassium bicarbonate, (c) one or more compounds selected from powdery naphthalenesulfonic acid compounds, ligninsulfonic acid compounds, oxypolycarboxylic acid compounds and melaminesulfonic acid compounds and (d) an alkali metal carbonate. The a/b ratio is 85/15 to 15/85, the amount of the component (c) is 0.02-3 pts.wt. and that of the component (d) is 0.02-10 pts.wt. based on 100 pts.wt. of a+b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bicarbonate hardener in a silicate soil stabilizing chemical.

[0002]

2. Description of the Related Art Conventionally, there has been known a ground stabilization method in which various chemicals are injected into the ground and gelled in the ground in order to strengthen the soft ground or stop water from leaking the ground. So-called silicate-based soil stabilization chemicals, which consist of an alkali silicate aqueous solution as the main agent solution and a combination of this and a hardening agent, are inexpensive and have a lower risk of causing pollution than other grouts. And is currently widely used.

[0003] The silicate-based soil stabilizing chemicals are adjusted to a desired gel time according to the purpose of the application and the condition of the ground by appropriately changing the amount of the hardening agent used. As the curing agent for these silicate grouts, various substances have been conventionally proposed.However, there is no danger and the handling is easy, and the gel time of the chemical solution can be changed from several seconds to several minutes by changing the amount of use. A hardening agent made of bicarbonate is widely used because it can be widely adjusted from a so-called instantaneous setting type to a loose setting type.

Further, the applicant has disclosed in Japanese Patent Application Laid-Open No. 08-277524 a combination of sodium bicarbonate and potassium bicarbonate in the range of 56:44 to 75:25 as a curing agent containing carbonate as a main component. Of silicate-based soil stabilization chemicals and soil stabilization methods that exhibit good strength of the hardened body and have less delamination phenomena.

When a conventional silicate soil stabilizer containing bicarbonate as a main component is stored for a long period of time, the hardener solidifies, and the hardener is dissolved in water to prepare a hardener liquid. There was a problem that the stirring blade of the dissolving tank was destroyed during the operation.

In addition, in the preparation of a curing agent liquid, especially when the weight ratio of the curing agent to the alkali silicate is increased in order to shorten the gel time, the dissolution time becomes longer, and the curing agent is dissolved in water to prepare the curing agent liquid. It took a long time to complete, and there were also problems in work such as prolonged construction. Furthermore, by changing the amount of the hardening agent used for the alkali silicate, when adjusting the gel time of the chemical solution to a so-called slow setting within a range of 10 seconds to several minutes or a so-called instant setting within 10 seconds of the gel time, The strength of the ground subjected to the stabilization treatment is low, and when the treated ground is cut, there is a problem that the ground collapses or cracks occur.

A silicate-based soil stabilizing chemical using a curing agent obtained by improving a bicarbonate-based curing agent described in Japanese Patent Application Laid-Open No. 08-277524 has excellent strength of a cured product, and
Although the phenomenon of segregation was small, the curing agent itself solidified when stored for a long period of time, and the dissolution time was long to prepare the curing agent liquid by dissolving the curing agent in water, and the construction was prolonged. There was a problem in the work, and improvement was desired. In addition, although the strength was improved compared to the case where a conventional bicarbonate hardening agent was used, it can be said that it is still sufficient in situations where further strength is required such as ultra soft ground. No further improvement was desired.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a hardening agent comprising bicarbonate in a silicate-based soil stabilizing solution, which hardly causes caking even when stored for a long time, and An object of the present invention is to provide a bicarbonate-based curing agent which has good solubility and good strength of a cured product to be formed.

In finding a hardening agent for the silicate soil stabilizer of the present invention, the following performance criteria are set, and when all of these performance criteria are satisfied, the object of the present invention has been achieved. .

(1) 450 g of a curing agent is placed in a 15 cm × 18 cm polyethylene vinyl bag (0.5 mmφ × 6 with pinholes), sealed, and used as a test specimen under a load of 0.2 N / mm ^2. It was stored for one year in a thermo-hygrostat at 35 ° C and 65% humidity. Thereafter, the sample was placed on a 12-mesh sieve, the weight A (g) remaining on the sieve and the weight B (g) passed through the sieve were measured, and the consolidation rate was calculated from the following equation, and the consolidation rate was calculated. Is less than 10%, the object was deemed to have been achieved. Consolidation rate (%) = A / (A + B) × 100

(2) Under an environment of 5 ° C., a curing agent of 20 k
Add water at 5 ° C so that the g and the curing agent liquid become 200 liters, and stir using a mixer (Powermix PM220B manufactured by Toshiba Corporation), and within 5 minutes until the curing agent is completely dissolved. If so, the goal was achieved.

(3) No. 3 sodium silicate specified in Japanese Industrial Standards (JIS K-1408) was used as an alkali silicate, and was prepared by mixing 80 liters of No. 3 sodium silicate and 120 liters of water. When the aqueous solution is used as the main solution (solution A),
A solution obtained by mixing an equal amount of the solution A and the solution B with the aqueous solution containing the curing agent as the solution B at a temperature of 20 ° C .; adjusting the amount of the curing agent in the solution B to reduce the gel time of the solution to 1 minute 30 minutes Seconds to 2 minutes 30
When adjusted to seconds (relaxation), the unconfined compressive strength value of the formed cured body (homogel body) after one day of gelation was 0.015 N
/ mm ² or more, and when the gel time of the chemical solution is adjusted to 7 to 10 seconds (flashing) by adjusting the amount of the curing agent of the solution B, the cured body (homogel body) formed after 1 day of gelation When the uniaxial compressive strength value was 0.045 N / mm ² or more, it was determined that the object was achieved.

[0013]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to improve the above problems and to solve the problems. As a result, the hardening agent in the silicate-based soil stabilizing chemical solution contains the bicarbonate-based hardening agent. Is a component: sodium bicarbonate, b component: bicarbonate of potassium bicarbonate and c component: naphthalenesulfonic acid compound, ligninsulfonic acid compound in powder form,
At least one selected from the group consisting of oxypolycarboxylic acid compounds and melamine sulfonic acid compounds; and
d component: an alkali metal carbonate, the amount ratio of which is a weight ratio, and the ratio of the a component to the b component in a specific range, (a component + b
Component) The component c is in a specific range per 100 parts by mass, and (a)
(Component + b component) It has been surprisingly found that the composition is such that the d component is in a specific range per 100 parts by mass, thereby satisfying all of the above performance criteria.

That is, the present invention provides a bicarbonate-based curing agent for use in a silicate-based soil stabilizing chemical solution, wherein the bicarbonate-based curing agent comprises component a: sodium bicarbonate, component b: potassium bicarbonate, Component c: powdery form, at least one selected from the group consisting of naphthalenesulfonic acid compounds, ligninsulfonic acid compounds, oxypolycarboxylic acid compounds, and melaminesulfonic acid compounds, and component d: alkali metal carbonate And the ratio of each component of the curing agent is a
The amount ratio of the component to the component b is 85:15 to 15:85, the component c is 0.02 to 3 parts by mass per 100 parts by mass of the total amount of the component a and the component b, and the component d is 100 of the total amount of the component a and the component b. 0.02 per part by mass
A bicarbonate-based curing agent in a silicate-based soil stabilizing chemical solution, wherein the content is in the range of 10 to 10 parts by mass. ”.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below.

The hardening agent in the soil stabilizing chemical solution of the present invention includes: a component: sodium bicarbonate, b component: potassium bicarbonate bicarbonate and c component: powdery naphthalenesulfonic acid compound, ligninsulfonic acid And at least one selected from the group consisting of oxypolycarboxylic acid compounds and melamine sulfonic acid compounds, and d component: alkali metal carbonate.

A group consisting of a component of sodium bicarbonate, a component of potassium bicarbonate, a naphthalenesulfonic acid compound, a ligninsulfonic acid compound, an oxypolycarboxylic acid compound and a melaminesulfonic acid compound in powder form. At least one kind selected from the above is abbreviated as c component, and the alkali metal carbonate is referred to as d component.

As the components a and b of the present invention, commercially available components can be used. The component c is a powdery naphthalene sulfonic acid compound is an alkali (earth) metal salt of naphthalene sulfonic acid or alkyl allyl sulfonic acid, or various derivatives in powder form such as a condensate of formalin thereof.
Commercially available products include, for example, Mighty 100 (manufactured by Kao Corporation).

The powdered lignin sulfonic acid compound of the component c is an alkali (earth) metal salt of lignin sulfonic acid or various powdery derivatives such as condensates of formalin thereof.
In commercial products, for example, Sunflow R (manufactured by Sunflow Co., Ltd.)
Can be raised. The polycarboxylic acid compound of the component c is a powdery derivative such as an addition or condensation polymer of an alkali (earth) metal salt of a compound having a carboxyl group,
For example, commercially available Palic # 1 (FPK Corporation)
)) Dried at 35 ° C. until the mass change is less than 0.1%.

The powdered melamine sulfonic acid compound of the component c is an alkali (earth) metal salt of melamine sulfonic acid or various powdery derivatives such as condensates of formalin thereof.
Commercially available products include, for example, SMF-PD (manufactured by Nissan Chemical Industries, Ltd.).

These c components are all powders, and use of a liquid component causes caking. The d component is
A compound represented by a chemical formula of M ₂ CO ₃ (M represents an alkali metal element of Li, Na, and K), and a commercially available compound can be used.

In the curing agent of the present invention, the ratio of the components a, b, c, and d is a component: b component = 8 by mass ratio.
5:15 to 15:85, and the c component is 0.02 to 3 parts by mass per 100 parts by mass of the (a component + b component), and (a component +
(b-component) A bicarbonate-based curing agent in a silicate-based soil stabilizing chemical liquid having a composition in which the d-component is in the range of 0.02 to 10 parts by mass per 100 parts by mass.

When the amount of component (a) or component (b) per 100 parts by mass of (a component + b component) in the curing agent is less than 15 parts by mass or from 85 parts by mass, based on the amount ratio range defined as the composition of the curing agent. When the content is too large, the above-mentioned performance standard is not satisfied with respect to the uniaxial compressive strength of the formed cured product, and the object of the present invention cannot be achieved.

In addition, the quantitative ratio of the component c is (component a + component b)
When the amount is less than 0.02 parts by mass per 100 parts by mass, compressive strength and solubility and consolidation at 5 ° C. are not satisfied, and when it is more than 3 parts by mass, neither of the above-mentioned properties is satisfied and the object of the present invention can be achieved. Can not.

The ratio of the amount of the d component is (a component + b component).
When less than 0.02 parts by mass per 100 parts by mass or 10
When the amount is more than the mass part, any of the above-mentioned performances regarding the consolidation is not satisfied, and the object of the present invention cannot be achieved.

Next, the alkali silicate as a main component of the silicate soil stabilizing chemical solution using the curing agent of the present invention includes those conventionally used in silicate soil stabilizing chemicals, for example,
No. 1 to 3 sodium silicate specified in Japanese Industrial Standards (JIS K1408), or silica sol having a SiO ₂ / Na ₂ O (molar ratio) in the range of 4 to 6 can be used. Also, the trade name "Nitroc" (manufactured by Mitsubishi Rayon Co., Ltd.) can be used.

Although these sodium silicates are generally in the form of an aqueous solution, they are further diluted with water at the time of construction to obtain an aqueous solution having an appropriate concentration suitable for stabilizing the soil. For example, in a normal construction method in which an aqueous sodium silicate solution (hereinafter abbreviated as solution A) and a hardener solution (hereinafter abbreviated as solution B) are mixed in equal volumes and injected into the ground, JIS No. 3 water glass is used as a sodium silicate source. In general, when A is used, a solution prepared by diluting 70 to 120 parts by volume of the sodium silicate with water to 200 parts by volume is used as the liquid A. The higher the sodium silicate concentration in the solution A, the greater the strength of the treated ground.

The aqueous solution (solution B) of the curing agent composition in the soil stabilizing solution of the present invention is prepared by mixing the solution A and the solution B at an appropriate ratio, for example, per 400 liters of the solution, for example, No. 3 silicate. When containing 80 liters of soda, the weight of the curing agent composition is not particularly limited, but is usually adjusted to be in a range of 10.0 kg to 35.0 kg. Within the above range, increasing the amount of the curing agent composition can shorten the gel time of the chemical, while decreasing the amount can increase the gel time of the chemical.

In actual ground stabilization, the liquid A is mixed with an alkali silicate as a main agent and water, and the liquid B is mixed with a curing agent composition specified in the present invention and water. An example is a method of stabilizing the ground by injecting and hardening a drug solution obtained by mixing and preparing the prepared A solution and the B solution at an appropriate ratio into the ground and hardening the same.

When injecting a chemical solution into the ground, a single tube type
It can be used for various injection tubes such as double tube type and multiple tube type. It is also possible to mix solution A and solution B in advance and guide them to the injection tube. Solution A and solution B are provided at the base between injections. Mixing part-for example, a method of mixing in a Y-shaped tube and leading to an injection tube, or a method of independently leading solution A and solution B to an injection tube and mixing in the injection tube, or solution A and solution B And the like can be independently guided to the injection pipe, and a suitable method such as merging and mixing in the ground while injecting into the ground from the injection pipe can be adopted according to the gel time of the chemical solution and workability.

[0031]

Next, the present invention will be described specifically with reference to examples and comparative examples. The present invention is not limited to these examples.

Sodium bicarbonate and potassium bicarbonate passed through a 24-mesh sieve are charged into a Nauta mixer so that the curing agent becomes 1 t, and the c component passed through a 24-mesh sieve is further charged. The alkali carbonate passed through a 24-mesh sieve was charged, and the mixture mixed for 30 minutes was used as a curing agent and used for the test. Note that sodium bicarbonate, potassium bicarbonate, and alkali carbonate were all reagents of the first grade.

The substances used for the component c are as follows. -Powdered naphthalene sulfonic acid compound: Mighty 100 (manufactured by Kao Corporation)-Powdered lignin sulfonic acid compound: Sunflow R
(Manufactured by Sunflow Co., Ltd.)-Powdered oxypolycarboxylic acid compound: Palic # 1
(FPK Co., Ltd.)) dried at 35 ° C. until the weight change becomes less than 0.1%. Powdered melamine sulfonic acid compound: SMF-PD (Nissan Chemical Industries, Ltd.) Fatty acid Alkyl ester: Pastel M-180 (manufactured by Lion Corporation)

The mass ratio of sodium bicarbonate and potassium bicarbonate of the curing agent composition in each test, the formulation of the curing agent composition in the solution B and the mixture (solution) of the solution A and the solution B,
Tables 1 and 2 show the measurement results, evaluation, and overall evaluation of each of the evaluation items of the chemical solution as the caking properties of the curing agent, the solubility of the curing agent in water, and the compressive strength of FIG.

The test methods and criteria for each evaluation item of the chemical solution performance are as follows. - Put the caking ... hardener 450g to 15cm × 18cm polyethylene plastic bags (those with a pinhole of 0.5 mm [phi × 6 months), the original and those that have been sealed specimen 0.02 N / mm ² load 35
It was stored for one year in a constant temperature and humidity room at 65 ° C and 65% RH. Thereafter, the sample was opened on a 12-mesh sieve, the weight A (g) remaining on the sieve and the weight passing through the sieve were measured B (g), and finally the consolidation rate was calculated from the following equation. Consolidation rate (%) = A / (A + B) × 100 Evaluation: The consolidation rate was less than 10%. ×: The consolidation rate was 10% or more.

Evaluation of solubility in water: Under an environment of 5 ° C., water of 5 ° C. was added to a drum can such that 20 kg of a hardening agent and 200 liters of a hardening agent liquid were mixed, and a mixer (Power Mix PM22) was added.
(0B manufactured by Toshiba Corporation) and the time until the curing agent was completely dissolved was measured. Evaluation: Completely dissolved within 5 minutes. X: It took 5 minutes or more to completely dissolve.

Uniaxial compressive strength of the cured product: The uniaxial compressive strength of the cured product was evaluated under the following conditions. Liquid A: Adjusted by adding 120 liters of water to 80 liters of JIS No. 3 sodium silicate. Liquid B: A predetermined amount of a curing agent was measured and water was added so that the volume became 200 liters, and the curing agent was completely dissolved to obtain a liquid B.

Each of the solution A and the solution B prepared as described above
50 ml of the mixture was mixed at a temperature of 20 ° C., and the mixed solution was poured into a cylindrical mold (diameter 5 cm × height 10 cm), and the uniaxial compressive strength value of the hardened material thus formed was measured on a daily basis.

Evaluation: The value of the uniaxial compressive strength of the cured product adjusted to the instantaneous setting of the gel time of 7 to 10 seconds is 0.045 N / mm ² or more and the setting time of the gel time is 1 minute 30 seconds to 2 minutes 30 seconds. The adjusted cured product had a uniaxial compressive strength value of 0.015 N / mm ² . ×: The value of the unconfined compressive strength of the cured product adjusted to a flash time of 7 seconds to 10 seconds is less than 0.045 N / mm ² or 1 minute 30 seconds to
The unconfined compressive strength value of the cured product adjusted to 2 minutes and 30 seconds is set to 0.
It was less than 015 N / mm ² .

Comprehensive evaluation: Evaluation of the uniaxial compressive strength, caking property, and solubility of the curing agent was all performed for the cured product. X: At least one of the evaluation items was x.

[0041]

[Table 1]

[0042]

[Table 2]

Experiments 1 to 5 show the effect of the weight ratio of sodium bicarbonate and potassium bicarbonate on the performance of the chemical solution in the composition of the curing agent, and on the solidification of the curing agent and the solubility in water. When the amount ratio of sodium bicarbonate in the curing agent composition is larger than the specified range of the present invention (Experiment 1) or smaller (Experiment 5), the above-mentioned performance criterion is applied to the unconfined compressive strength of the formed cured product. And none of them could achieve the object of the present invention.

Experiment 6 shows the effect on the performance of the chemical solution when the curing agent does not contain the component c, and on the solidification of the curing agent and the solubility in water. In this case, the uniaxial compressive strength of the formed cured product, the caking property of the curing agent, and the solubility in water were not satisfied with the above-mentioned performance standards, and the object of the present invention could not be achieved.

Experiments 7 to 11 show the effect of the total amount of bicarbonate and the mass ratio of the component c on the performance of the chemical solution and the solidification of the curing agent and the solubility in water in the curing agent composition. . When the amount ratio of the component c is less than the specified range of the present invention (Experiment 7), the uniaxial compressive strength of the formed cured product, the caking property of the curing agent, and the solubility in water are larger than the specified range. (Experiment 11) did not satisfy the above-mentioned performance criteria with respect to the caking property of the curing agent, and none of them could achieve the object of the present invention.

Experiments 12 to 16 show the effects of the total amount of bicarbonate and the mass ratio of the component B on the performance of the chemical solution, the solidification of the curing agent and the solubility in water in the curing agent composition. Show.
When the amount of the component B is less than the range specified in the present invention (Experiment 12) or higher than the range (Experiment 16), the above performance criterion is not satisfied with respect to the setting property of the curing agent. I could not do it.

Experiments 17 to 20 show, as comparative examples, the effects of the carbonates other than the present invention on the performance of the chemical solution and on the solidification of the curing agent and the solubility in water. When a carbonate other than the present invention was used, none of the evaluation criteria of the present invention was satisfied, and the object of the present invention could not be achieved.

On the other hand, when the conditions of the present invention were satisfied (Experiments 2 to 4, 8 to 10, 13 to 15), the gel time was adjusted to 7 to 9 seconds, and one day after the formation, and the unconfined compressive strength values is 0.045 N / mm ² or more, 1 minute 30 seconds to 2 minutes gel time
The unconfined compressive strength value after one day formed when adjusted to 30 seconds is 0.015 N / mm ² or more, and it is completely non-consolidated even if the curing agent is stored for 1 year under the pressure of 1 t / m ² In an environment of 5 ° C, measure 20kg of the curing agent so that the capacity becomes 200 liters.
Of water was added, and the time required for the curing agent to completely dissolve was within 5 minutes, all of which satisfied the performance standards of the above-mentioned chemicals and curing agent, and could achieve the object of the present invention.

[0049]

According to the hardening agent for the silicate-based soil stabilizing agent of the present invention, the performance which cannot be obtained by the combination of the conventional hardening agent compositions, that is, hardly causes caking even when stored for a long time, and It has good solubility in water, exhibits good strength of the cured body to be formed, and can stabilize the ground more safely and reliably.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C04B 22:10 C04B 22:10 24:22 24:22 A 24:18 24:18 A 24:06 24: 06 A 24:30) 24:30) B 103: 14 103: 14 C09K 103: 00 C09K 103: 00

Claims (1)

[Claims] 1. A bicarbonate-based curing agent used in a silicate-based soil stabilizing chemical solution, wherein the bicarbonate-based curing agent comprises a component:
Sodium bicarbonate, b component: potassium bicarbonate, c component:
A naphthalenesulfonic acid-based compound, a ligninsulfonic acid-based compound, an oxypolycarboxylic acid-based compound and a melaminesulfonic acid-based compound in the form of a powder; The ratio of each component of the curing agent is 85:15 to 15:85, and the c component is the total amount of the a component and the b component.
Bicarbonate in a silicate-based soil stabilizing chemical solution, wherein 0.02 to 3 parts by mass per 100 parts by mass and d component is in the range of 0.02 to 10 parts by mass per 100 parts by mass of the total amount of the component a and the component b. Salt-based curing agent.