JP2860718B2 - Ground improvement agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soil conditioner for grouting or the like.

[0002]

2. Description of the Related Art Various grout fillers have been used for improving the ground. Most of them are currently water glass or cement based.

[0003] Looking back on the history of grouting agents in Japan, in the 1960s, Higuchi proposed an unstable water glass grout (LW) with a short gel time combining a cement suspension and a diluted water glass solution. With improvements,
An unstable water glass grout (C-LW), which is a combination of a blast furnace colloid cement of fine particles and a low molar ratio water glass diluting solution, has a gel time of more than ten times, and has a high strength and high durability.
Furthermore, grout (MS) having a relatively long gel time based on a change in the mixing ratio of granulated blast furnace slag and Portland cement and combination with a water glass dilute solution at each molar ratio is based.

At present, for the purpose of infiltration, there are many solution types in which water glass and a curing agent are combined.

[0005] On the other hand, cement-based suspension type or semi-suspension type is also widely used because it is effective for obtaining high strength.

[0006]

However, the cement type suspension type or semi-suspension type can obtain high strength, but does not have high permeability to the ground.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to obtain a ground improver which utilizes the excellent hydraulic properties of calcium-containing materials such as granulated blast furnace slag, and has excellent permeability and strength after a long time. .

[0008]

According to the first aspect of the present invention, which solves the above problems, the content of calcium oxide is 20 to 50% by weight, and 90% or more of the internal structure is glassy. , A fine powder having a Blaine value of 5000 cm ² / g or more (A), sodium hydroxide (B), and a BET surface area of 4
One or more types (C) selected from the group consisting of hydrous silicic acid, hydrous calcium silicate, and hydrous aluminum silicate of 0 m ² / g or more;
0 to 500 kg / m ³ , and the above (B) is 200% based on 10% concentration.
500 l / m ^3, a soil improvement agent, wherein the (C) is a proportion of 0.01 to 1.0% by volume relative to the 10% sodium hydroxide solution.

The invention according to claim 2 is characterized in that a fine powder having a calcium oxide content of 20 to 50% by weight, 90% or more of the internal structure being vitreous, and having a Blaine value of 5000 cm ² / g or more, Sodium hydroxide or potassium hydroxide and BE
T is a soil conditioner characterized by being mainly composed of one or more selected from the group consisting of hydrous silicic acid, hydrous calcium silicate, and hydrous aluminum silicate having a surface area of 40 m ² / g or more. is there.

A third aspect of the present invention is the ground improver according to the first or second aspect, wherein the fine powder is a granulated blast furnace slag powder.

The invention according to claim 4 is the soil improver according to claim 1 or 2, wherein the fine powder has a Blaine value of 8000 to 16000 cm ² / g.

[0012]

Effect: The content of calcium oxide is 20-50% by weight, more than 90% of the internal structure is glassy, and the Blaine value is more than 5000 cm ² / g. When sodium hydroxide or potassium hydroxide is added, hydrolysis occurs, and the latent hydraulic property of the granulated blast furnace slag powder is developed.

When this material is injected into the ground, for example, practically sufficient compressive strength can be obtained, and a longer permeation distance can be obtained as compared with a fine cement-based injection material. Therefore, when the ground improver according to the present invention is used as an injection, an excellent ground improvement effect can be obtained.

On the other hand, in this case, when the blast furnace slag fine powder particles come into contact with an alkaline solution, the SiO ₂ , Al ₂ O ₃
Is eluted, and then Ca ²⁺ ions are eluted, whereby calcium silicate hydrate is formed on the surface of the slag particles, and the slag particles are cohesively bonded to each other.

As a result of this aggregation, as shown in the examples below, the strength develops early, and the strength after a long time elapse, for example, the 28-day strength is not sufficient. In addition, if coagulation progresses during storage or when construction is interrupted, permeability deteriorates.

Therefore, when a high strength is to be obtained after a long period of time, fine white carbon (in the present invention, hydrous silica, hydrous calcium silicate, hydrous silica having a BET surface area of 40 m ² / g or more) is used. When one (or one or more selected from the group of aluminum oxides) is added, it becomes sandwiched between slag particles as shown in FIG. However, these white carbon fine particles are gradually dissolved by an alkali solution, for example, a sodium hydroxide solution, to generate sodium silicate on the surface of the particles. This causes a weak bond between the slag particles.
Even if the slag particles are solidified in this state, as shown in the figure, when an external force such as a stirring force is applied, the slag particles are separated and separated from each other because the bonding is weak, and the suspension can be re-fluidized. Therefore, there is no trouble in storage.

From this, it can be inferred that a dilute water glass solution can be used in place of the fine powder white carbon. However, in fact, water glass molecules are bonded to the surface of each slag particle, and the entire surface of the slag particle is formed. It is coated with water glass molecules and gels faster. Further, the resilience after re-fluidization is poor, and the breathing becomes large.

On the other hand, the white carbon fine particles used in the present invention have no such problem.

[0019]

Now, the present invention will be described in further detail with reference to Examples. In the present invention, a fine powder having a calcium oxide content of 20 to 50% by weight, 90% or more of the internal structure being vitreous, and having a Blaine value of 5000 cm ² / g or more is used.

A typical example of this is fine powder of granulated blast furnace slag. Other metallurgical slags can also be used.

The content of calcium oxide is more preferably 25 to 35% by weight. The Blaine value is more preferably 8000 to 16000 cm ² / g in terms of permeability. In the case of coarse particles, permeability to the ground is poor. Even with a higher Blaine value, there is not much improvement in permeability,
In addition, the cost required for pulverization is increased.

An alkali is added to this type of slag. As the alkali, sodium hydroxide is preferable, but potassium hydroxide can be used except for cost, and it has been confirmed that the effect is basically the same.

Further, in the present invention, it is desirable to add fine white carbon. The fine white carbon of the present invention is one or more selected from the group consisting of hydrous silicic acid, hydrous calcium silicate, and hydrous aluminum silicate.

[0024] The BET surface area of the fine white carbon, 40 m ² / g or more, preferably be suitably used for 50 to 300 m ² / g. In particular, hydrous calcium silicate is desirable because it delays the rate of hydrolysis of the slag particles by the alkaline solution, so that the gel time can be easily adjusted.

The preferred formulation of the soil conditioner according to the present invention is as follows:
200-500 kg / fine powder containing calcium oxide (A)
m ^3, 10% sodium hydroxide at a concentration reference (B) 200 to
500 liter / m ³ , 10% white carbon (C)
It is 0.01 to 1.0% by volume based on the sodium hydroxide solution.

The fine powder containing calcium oxide causes a curing reaction even with a small amount of alkali, but it is preferable that the fine powder contains 200 liter / m ³ or more from the viewpoint of early development of strength. Conversely, if the amount of sodium hydroxide is excessive, alkali may remain in the ground and cause a factor that hinders the living environment. Depending on the concentration of sodium hydroxide, the amount added can be adjusted in first-order inverse proportion. For example, when the concentration is 5%, the concentration is 400 to 1000 l / m ³ . The addition amount of the white carbon fine particles is required to be 0.01% by volume or more in order to exert the effect. Conversely, if the amount is excessively large, the gel time will be shortened and the permeability will be impaired.

The soil improver according to the present invention can be prepared by mixing each material in advance and applying it to the target ground in a single solution, for example, it can be injected into the ground through an injection pipe. The suspension and the sodium hydroxide solution can also be fed separately to the injection tube and combined in the injection tube or in the ground. In this case, the above-mentioned white carbon can be added to one liquid side. Further, the ground improver according to the present invention can be used not only in the case of grout injection but also in other methods such as a stirring and mixing method as long as sufficient penetration is achieved.

[Examples] Comparative examples and examples are shown below to clarify the effects of the present invention. (Example 1) 3 of fine powder of granulated blast furnace slag (Brain value: 15000 cm ² / g)
Under a composition of adding 350 l / m ³ of 10% concentration sodium hydroxide to 50 kg / m ³ , hydrous silicic acid, hydrous calcium silicate and dilute water glass were added, and the change in viscosity was examined. . Table 1 shows the results. The amount added is% by volume.

[0029]

[Table 1]

From these results, it can be seen that the addition of hydrous silicic acid and hydrous calcium silicate can suppress the increase in viscosity and the effect of hydrous calcium silicate is greater than when dilute water glass is added. I understood. Also,
When it is 1.0% by volume or more, it has been found that the gelation time becomes short, which is not preferable.

(Example 2) Further, in each of the addition amounts of hydrated silicic acid, hydrated calcium silicate and diluted water glass, the kneading time was set to 10 minutes, and Toyoura standard sand was filled with an injection pipe. For the mold (diameter 5mmφ x length 100mm)
One solution was injected at an injection pressure of 1 kg / cm ² , and the results of examining its permeability and strength after 28 days are shown in Table 2. From these results, it was found that the addition of white carbon improved permeability and strength, and that hydrous calcium silicate had better permeability than hydrous silicic acid.

[0032]

[Table 2]

(Comparative Example) Fine cement (C) having a Blaine value of 15000 cm ² / g and water (W) were mixed at a mixing ratio of W / C = 250%, and a dispersant was mixed at a cement weight ratio of 1%. Under the same conditions as in Example 2, the permeability and the compressive strength of the fine-grain cement-based injection material produced by adding were examined.

As a result, the permeation distance was 25 cm,
The compressive strength after 64 days was 64 kgf / cm ² . From this, it was found that although the compressive strength after 28 days was high, the permeation distance was not sufficient, and it was not suitable as a ground improver for injection.

[0035]

As described above, according to the present invention, it is possible to utilize the excellent hydraulic property of the calcium-containing material such as the granulated blast furnace slag powder, and at the same time, improve the ground having excellent permeability and strength after a long time. Agent can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a reaction mechanism by adding white carbon to granulated blast furnace slag powder particles.

Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI C09K 17/12 C09K 17/12 P E02D 3/12 101 E02D 3/12 101 // C09K 103: 00 (72) Inventor Masatoshi Iio Chiyoda, Tokyo 4-56, Kudan-Kita-ku, Ward Inside Light Industry Co., Ltd. (56) References JP-A-2-107542 (JP, A) JP-A-59-193984 (JP, A) (58) Fields surveyed (Int. Cl. ⁶ , DB name) C09K 17/02 C04B 28/08 C04B 22/06 C04B 24/40 C09K 17/08 C09K 17/12 E02D 3/12 101

Claims (4)

(57) [Claims] 1. Fine powder (A) having a calcium oxide content of 20 to 50% by weight, at least 90% of its internal structure being vitreous, and having a Blaine value of 5,000 cm ² / g or more; (B) and one or more kinds (C) selected from the group consisting of hydrous silicic acid, hydrous calcium silicate, and hydrous aluminum silicate having a BET surface area of 40 m ² / g or more, (A) is 200 to 500 kg / m ³ , and (B) is 10%
200 to 500 liters / m ^{3 based on} the concentration;
A soil conditioner having a mixing ratio of 0.01 to 1.0% by volume based on 0% sodium hydroxide solution. 2. A fine powder having a calcium oxide content of 20 to 50% by weight, at least 90% of its internal structure being vitreous, and having a Blaine value of 5,000 cm ² / g or more, sodium hydroxide or hydroxide. Ground comprising potassium and one or more selected from the group consisting of hydrous silicic acid, hydrous calcium silicate, and hydrous aluminum silicate having a BET surface area of 40 m ² / g or more. Improver. 3. The soil improver according to claim 1, wherein the fine powder is a granulated blast furnace slag powder. 4. The fine powder has a Blaine value of 8000 to 16000 cm ² / g.
The soil improver according to claim 1 or 2, wherein