JPH04293994A - Soil conditioner - Google Patents

Abstract

PURPOSE:To improve the penetration of a soil conditioner, which is made by utilizing the excellent hydraulic property of a calcium-containing material such as a granulated blast-furnace slug, and the long-term strength of ground. CONSTITUTION:A soil conditioner obtained by using as principal components a fine powder which contains 20-50wt.% calcium oxide and has a Blaine's value of at least 5000cm<2>/g and in which at least 90% of the internal structure is made of a glassy material; sodium hydroxide or potassium hydroxide; and a white carbon having a BET surface area of at least 40m<2>/g.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soil improving agent for use in grouting, etc.

0002

BACKGROUND OF THE INVENTION Various types of grouting agents have been used for soil improvement. Most of the current materials are water glass-based or cement-based.

Looking back at the history of grouting agents in Japan, in the 1960s, Mr. Higuchi developed an unstable water glass grout (LW) with a short gel time, which was a combination of a cement suspension and a diluted water glass solution. With improvements, we have developed an unstable water glass grout (C-LW) with high strength and high durability, which has a gel time of more than 10 minutes, by combining fine particles of blast furnace colloidal cement and a water glass diluted solution with a low molar ratio.
), and is based on grout (MS) with a relatively long gel time, which is made by changing the mixing ratio of granulated blast furnace slag and Portland cement and combining water glass diluted solutions with various molar ratios.

At present, for the purpose of penetration, there are many solution-type products that combine water glass and a hardening agent.

However, suspension type or semi-suspension types are also widely used because they are effective in obtaining high strength.

[0006]

[Problems to be Solved by the Invention] When an alkali is added to a calcium-containing compound such as granulated blast furnace slag, hydrolysis occurs and the granulated blast furnace slag develops latent hydraulic properties. However, in this case, when the slag particles come into contact with an alkaline solution, SiO2 and Al2O3 in the slag are eluted, and then Ca2+ ions are eluted, thereby producing calcium silicate hydrate on the surface of the slag particles. The slag particles are coagulated and bonded to each other. As a result of this aggregation, strength develops early, and the strength after a long period of time, for example, after 28 days, is not sufficient. Furthermore, if aggregation progresses during storage or during construction interruptions, permeability will deteriorate.

Therefore, an object of the present invention is to utilize the excellent hydraulic properties of calcium-containing materials such as granulated blast furnace slag, and to obtain a ground improvement agent that has excellent permeability and strength after a long period of time. .

[0008]

[Means for solving the problem] The above problem is such that the content of calcium oxide is 20 to 50% by weight, and the internal structure is 9%.
0% or more is glassy and Blaine value is 5000cm
This problem can be solved by using as main ingredients a fine powder of 2/g or more, sodium hydroxide or potassium hydroxide, and white carbon with a BET surface area of 40 m2/g or more.

[0009] Examples of white carbon include silicic anhydride,
One or more selected from the group of hydrated silicic acid, hydrated calcium silicate, and hydrated aluminum silicate can be used.

[0010] The blending amount is 200 to 50% fine powder.
0 kg/m3, sodium hydroxide 200 to 500 liters/m3 based on 10% concentration, white carbon 0.01 to 10% sodium hydroxide solution
1.0% by volume is preferred.

[0011]

[Operation] When fine white carbon is added according to the present invention, it becomes sandwiched between slag particles as shown in FIG. However, these white carbon particles are
It is gradually dissolved in an alkaline solution, such as a sodium hydroxide solution, to form sodium silicate on the particle surface. This creates a weak bond between the slag particles. Even if the slag particles solidify in this state, as shown in FIG. 2, if an external force such as a stirring force is applied, the slag particles will separate from each other due to their weak bond and the suspension can be re-fluidized. Therefore, there is no problem during storage.

[0012] From this, it can be assumed that a dilute water glass solution can be used in place of the fine powder white carbon, but in reality, water glass molecules bond to the surface of each slag particle, and the entire surface of the slag particle is Covered by water glass molecules, which accelerates gelation. In addition, the restorability after refluidization is poor and breathing becomes large. On the other hand, white carbon fine particles have no such problem.

[0013]

EXAMPLES The present invention will be specifically explained in further detail below. In the present invention, a fine powder with a calcium oxide content of 20 to 50% by weight, an internal structure of 90% or more of glass, and a Blaine value of 5000 cm2/g or more is used.

A representative 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 8,000 to 16,000 cm2 in terms of permeability.
/g. Coarse particles have poor permeability into the ground. Even if the Blaine value is higher, no significant improvement in permeability can be expected, and the cost required for pulverization increases.

[0015] Alkali is added to this type of slag. As the alkali, sodium hydroxide is preferred, but potassium hydroxide can also be used except for cost, and it has been confirmed that the effects are basically the same. Furthermore, in the present invention, fine white carbon is added. As this fine white carbon,
One or more selected from the group of anhydrous silicic acid, hydrated silicic acid, hydrated calcium silicate, and hydrated aluminum silicate can be used. The BET surface area is 40 m2/g or more, preferably 50 to 300 m2/g.
g can be suitably used. In particular, hydrated calcium silicate is desirable because it delays the rate of hydrolysis of slag particles by an alkaline solution, making it easier to adjust the gel time.

[0016] A preferred formulation of the ground improvement agent according to the present invention is as follows:
200 to 500 kg of calcium oxide-containing fine powder
m3, sodium hydroxide is 200% based on 10% concentration.
~500 liters/m3, white carbon 10
% sodium hydroxide solution. Although a small amount of alkali causes a hardening reaction, the fine powder is preferably contained in an amount of 200 liters/m 3 or more for early development of strength. Conversely, if sodium hydroxide is excessive, alkali will remain in the ground,
There is a risk of causing factors that impede the living environment. Depending on the concentration of sodium hydroxide, the amount added can be adjusted in linear inverse proportion. For example, for a 5% concentration, 400
~1000 liters/m3. The amount of white carbon fine particles added is 0.01 to achieve the effect.
It is required to add more than % by volume. On the other hand, if the amount added is too large, the gel time will be shortened and the permeability will be inhibited.

The ground improvement agent according to the present invention can be applied to the target ground as a single solution by preparing each material in advance, for example, by injecting it into the ground through an injection pipe. The suspension and the sodium hydroxide solution can be fed separately into the injection tube and mixed together in the injection tube or in the ground. In this case, white carbon can be added to one liquid side. Furthermore, the ground improvement agent according to the present invention can be used not only for grout injection but also for other construction methods such as stirring and mixing construction methods.

[Example] Examples are shown below to clarify the effects of the present invention. (Example 1) Fine powder of granulated blast furnace slag (Blaine value 15
1 for 350kg/m3 of 000cm2/g)
350 liters/m3 of 0% sodium hydroxide
Hydrous silicic acid, hydrated calcium silicate, and diluted water glass were added to examine changes in viscosity. The results are shown in Table 1. The amount added is % by volume.

[0019]

[Table 1]

[0020] From this result, it is found that the increase in viscosity can be suppressed more when adding hydrated silicic acid and hydrated calcium silicate than when diluted water glass is added, and hydrated calcium silicate has a greater effect. It turns out. Also,
When the content is 1.0% by volume or more, the gelation time becomes shorter;
I also found that I didn't like it. (Example 2) Furthermore, in each addition amount combination of hydrated silicic acid, hydrated calcium silicate, and diluted water glass, the kneading time was set to 10 minutes, and a mold (diameter 5mmΦ×Length 100
Table 2 shows the results of investigating the permeability and strength after 28 days by injecting a single liquid into the sample (mm) at an injection pressure of 1 kg/cm2. These results revealed that the addition of white carbon improved permeability and strength, and that hydrated calcium silicate had better permeability than hydrated silicic acid.

[0021]

[Table 2]

[0022]

As described above, according to the present invention, it is possible to utilize the excellent hydraulic properties of calcium-containing substances such as granulated blast furnace slag, and also to create a ground improvement agent that has excellent permeability and strength after a long period of time. Obtainable.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the reaction mechanism due to the addition of white carbon to granulated blast furnace slag particles.

Claims (3)

[Claims] Claim 1: A fine powder having a calcium oxide content of 20 to 50% by weight, an internal structure of 90% or more of glass, and a Blaine value of 5000 cm2/g or more, and sodium hydroxide or potassium hydroxide. and white carbon having a BET surface area of 40 m2/g or more as main ingredients. 2. The ground improvement agent according to claim 1, wherein the white carbon is one or more selected from the group consisting of anhydrous silicic acid, hydrated silicic acid, hydrated calcium silicate, and hydrated aluminum silicate. Claim 3: Fine powder is 200 to 500 kg/m3
, sodium hydroxide is 200 to 50 on a 10% concentration basis.
2. The soil improvement agent according to claim 1, wherein the white carbon is 0.01 to 1.0% by volume based on the 10% sodium hydroxide solution.