JP2979726B2 - Self-hardening stabilizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-hardening stabilizer which can reduce the blending amount of bentonite, has a low breathing rate and can form a solidified wall having high strength.

[0002]

2. Description of the Related Art As a method of constructing an underground continuous wall, a drilling trench is filled with a bentonite stabilizing solution or a polymer stabilizing solution to prevent collapse of the trench wall,
After the excavation is completed, a method of lowering the reinforced basket into the groove where the stabilizing liquid is stored, further casting concrete, and replacing the stabilizing liquid with concrete to form a reinforced concrete underground continuous wall is known. This method is suitable for producing a solid wall.

[0003] Apart from this method, there is a method of inexpensively forming an underground continuous wall which is inferior in strength but sufficient as a temporary retaining wall or the like. The method uses a self-hardening stabilizer at the time of excavation, and forms a solidified wall by leaving the stable solution as it is after the excavation. This is called a self-hardening stabilizer method. In addition, as a deformation method of this, there is also a method of forming a solidified wall by casting a self-hardening stabilizer instead of the concrete after excavation using muddy water, which is required for the self-hardening stabilizer used in these methods. The performance is as follows.

(1) Performance before solidification: Before solidification, it is necessary to have a function of preventing collapse of the excavation trench and a property of separating from excavated earth and sand. For that purpose, an appropriate specific gravity and viscosity are necessary, and the specific gravity is generally 1.15 to 1.
25. It is considered that a funnel viscosity of about 25 to 35 seconds is appropriate as the viscosity.

The range of the funnel viscosity is 25 to 35.
If the time is set to less than 25 seconds, the breathing described later becomes extremely large, and if it is more than 35 seconds, it becomes difficult to separate the excavated earth and sand.

The next important thing is that the amount of breathing water is low. Breathing is a phenomenon in which, when a self-hardening stabilizing liquid is left after completion of excavation, a part of the internal moisture gradually moves upward and accumulates on the upper surface until it solidifies. If this amount is large, the volume of the solidified portion will be reduced by that much, and a defect will occur at the upper part, so the defect must not only be supplemented with the self-hardening stabilizer at a later date, but also the groove wall will be formed at the part where breathing occurred Even the risk of collapse comes out. Therefore, the smaller the breathing rate is, the better, it is preferable to keep it to 10% or less.

(2) Performance after solidification: The most important performance after solidification is strength. Target strength, some depending on the type of object or structures construction work, for example, the uniaxial compressive strength at Zaihiya 28 days is required to be about 5~15Kgf / cm ^2.

Conventionally, in order to obtain such performance, a self-hardening stabilizer is prepared by using "water + bentonite + cement-based solidifying material + hardening retarder" or "water + bentonite + a general clay with low activity + cement-based. It is prepared by mixing a "solidifying material and a curing retarder". In this case, the water is equivalent to the kneading water in concrete, and it is desirable to use fresh water as much as possible.However, seawater may have to be used due to difficulties in obtaining it at the construction site, etc. The kneading and the latter are called seawater kneading. The hardening retardant is used for maintaining the fluidity of the self-hardening stabilizer during excavation, and the amount of the hardening retarder is appropriately adjusted according to the working time and the like. In general, natural bentonite is used. However, such a conventional self-hardening stabilizer has technical problems described below.

[0009]

[Problems to be solved by the invention]

(1) Problems in seawater kneading: In the case of seawater kneading, there is no problem with the reaction of the solidified material in the self-hardening stabilizing solution, but the behavior of bentonite is completely different from that of fresh water, and swelling is significantly suppressed. As a result, not only does the viscosity of the self-hardening stabilizer decrease, but also the breathing becomes extremely large, and the self-hardening stabilizer no longer functions. Bentonite is a clay mainly composed of a highly swellable clay mineral called montmorillonite, but its swelling is suppressed in a liquid containing a large amount of electrolytes such as seawater. Are known.

[0010] As a solution to such a problem, in the case of seawater kneading, the amount of bentonite is increased to twice or more the standard of the fresh water blending, and a general clay such as kaolin is used in combination. . As another measure, a standard amount of bentonite is used in combination with a clay mineral having a fiber structure such as, for example, attapulgite or sepiolite, or a water-soluble cellulosic polymer is used in combination with the bentonite or fiber structure clay. In some cases.

[0011] However, such a solution has the problems that not only the amount of materials is increased and the material cost is extremely high, but also the types of materials to be handled are increased and the construction is complicated.

(2) Problems in Shimizu kneading: Even in Shimizu kneading, breathing water is generated until the self-hardening stabilizing liquid is hardened, and the amount of the generation is a considerable number. The volume of the breathing water when the volume of the original self-hardening stabilizing liquid is 100 is displayed as the breathing rate (%).
Before and after. In ordinary construction, such a breathing rate can be dealt with by replenishing the self-hardening stabilizing solution to the defective part due to breathing the next day.

However, due to the formation of the defective portion, the breathing rate becomes a problem in the construction on soft ground where there is a fear that the groove wall of the defective portion may collapse or in the filling work of the hollow portion. As a countermeasure, the amount of bentonite is increased by 20 to 50% of the standard composition, but there is a disadvantage that the material cost is increased.

The present inventors have conducted experiments using various materials to solve the above problems, and as a result, focused on activated bentonite. By using this as a material for the self-hardening stabilizer, it is possible to maintain the appropriate specific gravity and viscosity even with a small amount of compounding, keep the breathing rate low, and form a wall with high compressive strength after curing. It has been found that a self-hardening stable liquid can be obtained, and the present invention has been completed.

[0015]

To achieve the above object, according to an aspect of the present invention, water, bentonite, in self-hardening stabilizer formulation which only cement solidifying material is mainly made, funnel
All or part of the bentonite was constituted by activated bentonite so that the viscosity was in the range of 25 to 35 sec . Also, the present invention, water, bentonite,
Self-hardening stabilizer containing only cement-based hardener
In the above, all or a part of the bentonite may be activated bentonite so that the breathing rate is 10% or less. The difference between natural bentonite and activated bentonite in the present invention is defined as follows.

Natural bentonite: mining and drying raw ore,
It is obtained by an operation of grinding and sieving to the required particle size. Some of them have been artificially treated to the extent that a small amount of a swelling agent such as sodium carbonate is added, if necessary, but their properties are essentially the same as those obtained by sieving.

Activated bentonite: The raw material is a natural clay as described above. For example, as shown in JP-A-63-50310, cristobalite inevitably contained in acid clay is converted to sodium silicate. It is one that has been subjected to an alkali treatment without being treated, or a similar one. Its properties are remarkable swelling properties and novel rheological properties as compared with natural bentonite, and it has excellent resistance to electrolytes contained in seawater and the like.

The activated bentonite may be a solution containing not only seawater but also other electrolytes such as salts, for example, factory drainage water, water used for draining concrete, river water in tidal areas, spring water in hot spring areas, and groundwater. It is also characterized by its ability to swell against various types of water, such as the muddy water collected when concrete is cast in the medium wall construction method, which has been thought to have an adverse effect on bentonite swelling.

Next, each of the materials and the amounts thereof will be described. (1) When seawater is used as water: All or part of bentonite in the standard composition shown in the section of the prior art is replaced with activated bentonite. In addition, by setting the blending amount of the activated bentonite at this time to 60 to 160 kg, the viscosity is set to a range of 25 to 35 sec in funnel viscosity, and the breathing rate is set to 10% or less. (2) When using clear water as water: All or part of bentonite in the conventional standard composition is replaced with activated bentonite. Further, by setting the blending amount of the activated bentonite at this time to 20 to 70 Kg, the viscosity is set in the range of 25 to 35 sec in funnel viscosity, and the breathing rate is set to 10% or less.
Note that activated bentonite has no adverse effect on natural bentonite and natural bentonite, and thus can be used in combination with natural bentonite as described above.

Next, as a cement-based solidifying material, a cement containing a large amount of blast furnace slag slag which is usually finely pulverized to a Blaine value of about 4000 cm ² / g is excellent in terms of solidification strength, but is not limited to this. It is possible to use ordinary portland cement, blast furnace cement, fly ash cement, and various cement-based solidification materials made for improving the ground.

Further, a small amount of a curing retarder may be added as required for the operation. As the curing retarder, for example, polycarboxylates, oxycarboxylates, ligninsulfonates, naphthalenesulfonates, glumanates, and the like can be used.

It should be noted that both the cement-based solidification material and the setting retarder do not have any adverse effect on activated bentonite.
The blending amount can be appropriately increased or decreased according to the compressive strength to be obtained under an appropriate basic blending, workability, and the like.

The blending method is the same as that using natural bentonite. Water (fresh water or seawater) is put into a mixer, and the activated bentonite and, if necessary, general clay or fiber-structured clay per 1000 liters of water are mixed. A predetermined amount is charged based on the above-mentioned numerical range, mixed for about 3 to 5 minutes (however, if fiber structure clay is used, mixing for 10 to 20 minutes is necessary), transferred to an agitator and stirred to remove bentonite. Inflate well. The thus obtained muddy water is again transferred to another mixer, to which a cement-based solidifying material and, if necessary, a setting retarder are added and mixed for 3 to 5 minutes. By these operations, a predetermined amount of a self-hardening stable liquid can be obtained.

[0024]

[Function] Even with water containing electrolytes such as seawater kneaded or other salts, it has a sufficient swelling property, so that a self-hardening stable liquid can be made with the same simple material blending as Shimizu kneading, and the expected performance The composition ratio for obtaining the same is only a slight increase in the amount of bentonite compared to Shimizu kneading. In the case of shimizu kneading, the amount of bentonite can be further reduced. Further, the strength after solidification is considerably higher than in the case of using natural bentonite, especially in seawater kneading.

[0025]

First of all, a simple material composition can be used for seawater kneading, and the desired performance can be obtained by slightly increasing the compounding ratio of activated bentonite as compared with the case of fresh water, so that the construction is simple and the material cost is reduced. In addition to being able to use seawater, any water can be used effectively. In addition, the amount of bentonite can be significantly reduced in the fresh water kneading than in the past, and the material cost can be reduced. Further, since the strength after solidification can be greatly increased as compared with the related art, the amount of solidified material for obtaining a certain strength can be reduced.

[0026]

Embodiments will be described below. However, the present invention is not limited to only the following examples.

Example 1: Preparation and measurement of a self-hardening stabilizer by seawater kneading: Activated bentonite A and B having the properties shown in FIG. 1 and conventional natural bentonite used as a comparative example were mixed in 80 l each of 1 liter of seawater. ２００200 g, and these were stirred and mixed with a household juicer mixer for 30 seconds, respectively, and the funnel viscosity of each mud obtained immediately was measured. The measurement results shown in FIG. 2 were obtained. In FIG. 2 and subsequent figures, the blending amount (K
g). This result indicates that the viscosity of natural bentonite is generally lower at the same dosage.

Next, a cement-based solidifying agent was added to each muddy water, and the mixture was mixed with a home juicer mixer for 30 seconds to form a self-hardening stable liquid. The funnel viscosity was measured immediately, and the measurement results shown in FIG. 3 were obtained. . The measurement results indicate that natural bentonite requires 200 kg for 1000 liters of seawater, for example, to make the funnel viscosity 24 seconds. In contrast, activated bentonite is understood to be 100 kg, which is about half that of the conventional case.

Next, the obtained self-hardening stabilizer was poured into a cylinder having a diameter of 3 cm and a length of 7 cm. After being cured in water at 20 ° C. for a predetermined period, the breathing rate and the uniaxial compressive strength were measured. The result shown in FIG. 5 was obtained. FIG. 4 shows the breathing rate at the time of completion of curing. Comparing the case where the amount of bentonite was the same, the breathing rate when activated bentonite was used was 1/2 or less as compared with that of natural bentonite. It shows that the breathing inhibiting effect of bentonite is very large.

FIG. 5 shows the uniaxial compressive strength at the ages of 3, 7, and 28 days. The cement-based solidified material is the same.
From the measurement results, when activated bentonite was used, the strength of natural bentonite was considerably higher at the age of 3 days, and the strength was equivalent to 28 days of the natural bentonite at the age of 7 days. Showed about twice the strength of natural bentonite. From this, activated bentonite is very advantageous in terms of solidification strength as compared to natural bentonite, and conversely, the amount of cement-based solidification material can be reduced to obtain the same strength,
It suggests that it is advantageous in terms of cost.

Example 2: Production and measurement of a self-hardening stabilizer by kneading with fresh water: The seawater in Example 1 was changed to fresh water, and then the funnel viscosity in a mudified state was measured by the same method. When the self-hardening stabilizer was obtained, the funnel viscosity was measured, and the bleeding rate after curing,
When the uniaxial compressive strength was measured, the measurement results shown in FIGS. 6 to 9 were obtained.

First, activated bentonite has a high funnel viscosity even in the muddy state shown in FIGS. 6 and 7 or in the stage of being made into a self-hardening stabilizer. FIG.
From the results shown in the above, in order to adjust the funnel viscosity to 25 seconds, natural bentonite requires 50 kg per 1000 liters of fresh water, whereas activated bentonite requires only 20 kg, which can save about 60% of conventional materials. Is suggested. Also, the breathing rate using activated bentonite is 1/4 of that of natural bentonite from the breathing rate in FIG. 8, suggesting that the deterrent effect is extremely large.

Further, from the result of comparing the uniaxial compressive strengths shown in FIG. 9, there is no significant difference between the ages of 3 and 7 days, but a clear difference occurs on the 28th day. Even in this case, it is suggested to be advantageous in terms of compressive strength.

In each of the above embodiments, only activated bentonite was used simply, and a comparison was made with natural bentonite. However, activated bentonite and natural bentonite were mixed according to the characteristics to be obtained. It may be used, or another material such as a fiber structure clay may be used as a mixture.

[Brief description of the drawings]

FIG. 1 is a table showing physical properties of activated bentonite A and B used in Examples and natural bentonite used in Comparative Examples.

FIG. 2 is a graph showing the funnel viscosity of activated bentonite A, B and natural bentonite in a muddy state in Example 1.

FIG. 3 is a graph comparing funnel viscosities in a state immediately after producing a self-hardening stabilizer using activated bentonite A, B and natural bentonite.

FIG. 4 is a graph comparing the breathing rates of the same self-hardening stabilizer.

FIG. 5 is a graph comparing the uniaxial compressive strengths of the self-hardening stabilizer.

FIG. 6 is a graph showing the funnel viscosity of activated bentonite A, B and natural bentonite in a muddy state in Example 2.

FIG. 7 is a graph showing a comparison of funnel viscosities in a state immediately after production of a self-hardening stabilizer using activated bentonite A, B and natural bentonite.

FIG. 8 is a graph comparing the breathing rates of the self-hardening stabilizer.

FIG. 9 is a graph comparing uniaxial compressive strengths of the self-hardening stabilizer.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-209879 (JP, A) JP-A-63-50310 (JP, A) JP-A-60-101181 (JP, A) JP-A-1- 111760 (JP, A) JP-A-63-21248 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C09K 7/00-7/02 C09K 17/00

Claims (2)

(57) [Claims] 1. A water, bentonite, in self-hardening stabilizer formulation which only cement solidifying material is mainly made, Fan'ne
A self-hardening stabilizer, wherein all or part of the bentonite is constituted by activated bentonite so that the viscosity of the bentonite is in the range of 25 to 35 sec . 2. The method of claim 1 wherein water, bentonite and cement-based solidified material are used.
In a self-hardening stabilizer composed mainly of
As's modulus falls below 10%, all or part of the bentonite, self-hardening stabilizer you characterized by being configured by activated bentonite.