JP2904626B2 - 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.

However, a suspension type or a semi-suspension type is also widely used because it is effective for obtaining high strength.

[0006]

When an alkali is added to a compound containing calcium, such as granulated blast furnace slag, hydrolysis occurs, and the latent hydraulic property of the granulated blast furnace slag is developed. Utilizing this property, the applicant of the present invention has previously disclosed, as Japanese Patent Application No. Hei 3-60494, the superior hydraulic property of calcium-containing materials such as granulated blast furnace slag, as well as the permeability and the long-term permeability. As a soil improver with excellent strength, the content of calcium oxide is 20-50% by weight, more than 90% of the internal structure is glassy, and the Blaine value is 5000cm ² / g
A soil conditioner comprising the above fine powder, sodium hydroxide or potassium hydroxide, and white carbon having a BET surface area of 40 m ² / g or more has been proposed.

[0007] In this case, as will be clarified later in the embodiment, the strength increases over time. For example, 2
Eight days of compressive strength of about 50 kgf / cm ² .

[0008] However, it is usually preferable that the strength is high. However, when the ground is improved, the reinforced ground may be excavated once. In such an application, the strength is unified over time. It is not preferable that the intensity increases linearly, and it is desirable that the intensity does not increase any more after a certain time, or that the gradient increases even if it does increase.

[0009] Therefore, an object of the present invention is to ensure that the strength is practically sufficient and that the strength does not increase so much due to aging.

[0010]

The object of the present invention is that the content of calcium oxide is 20 to 50% by weight, and that the content of the internal structure is 9%.
0% or more is vitreous and has a Blaine value of 5000 cm2 / g
The problem is solved by using the above-mentioned fine powder, sodium hydroxide or potassium hydroxide, white carbon with a BET surface area of 40 m2 / g or more, and an admixture, which is a mixture of the following fine powders of limestone and clay, as the main components. it can. (Admixture) Ig. loss 20 ~ 30% SiO2 15 ~ 25% Al2O3 7 ~ 10% Fe2O3 3 ~ 7% CaO 60 ~ 70% MgO 0.7 ~ 2% SO3 1% or less Here, “Ig.loss” means ignition loss Show. In this case, as the white carbon, one or more kinds selected from the group consisting of silicic anhydride, hydrous silicic acid, hydrous calcium silicate, and hydrous aluminum silicate can be used. Also, the fine powder is 200-500 kg / m
3. 200% to 500L / m @ 3 of sodium hydroxide and 0.01% to 1.0% by weight of white carbon based on 10% sodium hydroxide solution based on 10% concentration. It is desirable that this is the case.

[0011]

The blast furnace slag can be used as the fine powder according to the present invention. For this slag particles, alkaline i.e. sodium hydroxide _{stimulates, CaO-MgO-Al 2 O} 3 -nH 2 O becomes hydrated product occurs. The admixture used in the present invention is a mixture of limestone fine powder and clay fine powder. Therefore, the fine powder of limestone and alkali react as follows. Fine powder of CaCO ₃ + NaOH → Ca (OH) ₂ + Na ₂ CO ₃ clay also causes the following reaction with alkali: R ₂ O ・ XAl ₂ O ₃・ YSiO ₂・ nH ₂ O + NaOH → Na ₂ SiO ₃ (soluble Ca (OH) ₂ formed with fine powder of silicic acid and clay reacts, and R ₂ O ・ XAl ₂ O ₃・ YSiO ₂・ nH ₂ O + Ca (OH) ₂ → Ca-clay (calcium clay) Ca-clay The Na ₂ CO ₃ formed by the reaction of Na ₂ CO ₃ reacts with Ca−clay + Na ₂ CO ₃ → Na−clay + CaCO ₃ Ca−clay to react with the Na ₂ SiO ₃ formed by Ca−clay + Na ₂ SiO ₃ → Na -Clay + CaSiO ₃ (calcium silicate) is formed. The above reactions (1) to (3) occur in a chain, and fine particles of calcium silicate generated by the pozzolanic reaction are effectively interposed between the slag particles to ensure the strength. Also,
The white carbon serves as soluble silicic acid.

On the other hand, if it is not desired to increase the strength as described above, it is conceivable to reduce the amount of slag. However, the amount of slag is set to, for example, 1 m ³ of soil when the porosity is 40%. when the 350 kg / m ^3, the gap filling rate
When the slag amount is, for example, 200 kg / m ³ , while the 28-day compressive strength is 50 kgf / m ³ at 59%, the 28-day compressive strength is 0 to 4 kgf / m when the gap filling rate is 34%. m ³ is extremely low and is not suitable for practical use. Therefore, with the improved material proposed above, only a material having high strength can be obtained. This is the same as the fact that the cement water ratio (W / C) of the cement paste determines the strength.

However, when the above-mentioned admixture is used according to the present invention, the strength is developed to the extent that practicality is satisfied, and an excessive increase in long-term strength can be suppressed.

[0014]

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.

As a typical example, fine powder of granulated blast furnace slag can be mentioned. 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, fine white carbon is added. As this fine white carbon,
One or two or more selected from the group consisting of anhydrous silicic acid, hydrous silicic acid, hydrous calcium silicate, and hydrous aluminum silicate can be used. As BET surface area,
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.

In the present invention, an admixture as a mixture of the following fine powder of limestone and fine powder of viscosity is used in combination with the slag. _{Ig.loss 20~30% SiO 2 15~25% Al} 2 O 3 7~10% Fe 2 O 3 3~7% CaO 60~70% MgO 0.7 ~2% SO 3 1% or less in this case, as the particle size configuration Is 1-5 μm on average, 1 maximum
Fine powders of the order of 5 μm are preferred.

The preferred formulation of the ground improver according to the present invention is as follows:
Calcium-containing fine oxide powder ^{200 ~500 kg / m 3, 10} %
200-500 liters / m of sodium hydroxide based on concentration
^{3. The amount} of white carbon is 0.01 to 1.0% by weight based on 10% sodium hydroxide solution, and the amount of the admixture is 60% by weight or more based on the fine powder.

The fine powder causes a curing reaction even with a small amount of alkali, but in view of early development of strength, 200 l / l.
It is preferable to contain m ³ or more. 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 liter / m ³ . The addition amount of the white carbon fine particles is required to be added at 0.01% by weight 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 admixture is desirably 60% by weight or more based on the fine powder. 60% by weight
If less, the strength tends to be excessive.

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 one solution, for example, by injecting into the ground through an injection pipe. The suspension and the sodium hydroxide solution can be separately fed into an injection tube and combined in the injection tube or in the ground. In this case, white carbon can be added to one liquid side. Further, the ground improver according to the present invention can be used in other methods such as a stirring and mixing method in addition to grouting.

[Examples] Examples will be shown below to clarify the effects of the present invention. (Assuming Experimental Example 1) with respect to the soil 1 m ^3, fine powder (Blaine value of granulated blast furnace slag
15000 cm ² / g) at 350 kg / m ³ , and 10 liters of sodium hydroxide at 350 l / m ³ ,
Hydrous silicic acid, hydrous calcium silicate and diluted water glass were added, and the change in viscosity was examined. However, the admixture of the present invention was not added. Table 1 shows the results. The amount added is% by weight.

[0022]

[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. (Prerequisite Experimental Example 2) In addition, in each addition amount blend containing hydrated silicic acid, hydrated calcium silicate and diluted water glass, a kneading time was set to 10 minutes, and a mold filled with Toyoura standard sand through an injection pipe ( Diameter 5mmΦ × length 100
mm), a one-liquid injection was performed at an injection pressure of 1 kg / cm ² , and the results of examining the permeability and the strength after 28 days were as follows:
The results 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.

[0024]

[Table 2]

(Examples 1 and 2) Example 1 of a premise experiment
When the amount of the following admixture (“SKF” manufactured by Mitsubishi Materials Corporation) with respect to the blast furnace slag was changed when the white carbon was 0.25% by weight in cm ² , penetration length 50
cm), the results of FIGS. 1 and 2 were obtained. (Composition of admixture) Ig.loss 23.70% SiO ₂ 20.73% Al ₂ O ₃ 7.92% Fe ₂ O ₃ 4.83% CaO 63.31% MgO 1.09% SO ₃ 0.72% Table 3
The result shown in FIG.

[0026]

[Table 3]

(Consideration) According to these results, the use of the admixture can suppress the increase in viscosity over time without impairing the permeability to the ground, and not excessive strength, but excavation sufficiently after strengthening the ground. It turns out that an improved body having a possible strength can be obtained.

[0028]

As described above, according to the present invention, a ground improver which can utilize the excellent hydraulic property of calcium-containing materials such as granulated blast furnace slag, and has an appropriate permeability and strength after a long period of time. Can be obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing a change in viscosity over time due to a difference in the amount of an admixture added.

FIG. 2 is a bar graph showing the results of a study on permeability due to differences in the amount of admixture added.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ubert Batmon 92000 Nanterre City, Wattfall Avenue 6 Soletanche Enterprise (58) Field surveyed (Int.Cl. ⁶ , DB name) C09K 17/06 C09K 17/10 C09K 17/12 E02D 3/12

Claims (3)

(57) [Claims] 1. 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 at least 5000 cm ² / g, sodium hydroxide or hydroxide. A soil conditioner comprising, as main components, potassium, a white carbon having a BET surface area of 40 m ² / g or more, and an admixture which is a mixture of limestone and clay fine powder described below. (Admixture) Ig.loss 20-30% SiO ₂ 15-25% Al ₂ O ₃ 7-10% Fe ₂ O ₃ 3-7% CaO 60-70% MgO 0.7-2% SO ₃ 1% or less 2. The soil conditioner according to claim 1, wherein the white carbon is at least one member selected from the group consisting of silicic anhydride, hydrous silicic acid, hydrous calcium silicate, and hydrous aluminum silicate. (3) 200-500 kg / m ^{3 of} fine powder, 200-500 liter / m ^{3 of} sodium hydroxide based on 10% concentration, and 0.2% of white carbon in 10% sodium hydroxide solution.
01 to 1.0% by weight, and the admixture is 60% based on the fine powder.
The soil conditioner according to claim 1, which is not less than% by weight.