JP2549949B2 - 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 ground improvement agent for grouting and the like.

[0002]

2. Description of the Related Art Various kinds of grout injection agents for improving the ground have been conventionally used. Most of the present days are mostly water glass or cement.

Looking back on the history of grouting agents in Japan, an unstable water glass grout (LW) developed by Mr. Higuchi in the 1960s, which combines cement suspension and diluted water glass liquid, and has a short gel time, In addition to this LW, by combining fine particle blast furnace colloid cement and a low molar ratio water glass diluted solution, unstable water glass grout (C-
LW), and a grout with a relatively long gel time (M) in which the mixing ratio of granulated blast furnace slag and Portland cement was changed and water glass diluted solution of each molar ratio was combined.
S) is the basis.

At present, for the purpose of permeation, there are many solution-type ones in which water glass and a curing agent are combined.

On the other hand, the applicant of the present invention has filed Japanese Patent Publication No.
In the gazette, it was disclosed that a solid body having high strength can be obtained by using so-called activated water glass.

[0006] On the other hand, it is also known that when an alkali is added to a compound containing calcium such as granulated blast furnace slag, hydrolysis occurs and latent hydraulic properties of granulated blast furnace slag are developed.

[0007]

As described above, although it is known to react a calcium oxide-containing substance with a silicate solution, this type of grout has a relatively short gel time, and Not necessarily highly penetrable.

When the activated water glass described in the above publication is used as an alkali stimulant for ground granulated blast furnace slag, the molar ratio of SiO ₂ / Na ₂ O (hereinafter, also simply referred to as molar ratio)
If it is high, the permeability is not sufficient. Further, when the groundwater contains a large amount of electrolyte, the permeability is particularly poor. Improvement
One of the factors that affects the permeability of the agent is the amount of active liquid added.
Yes, as shown in the examples below, the amount of active liquid added
Permeability can also be improved by reducing
However, the strength is reduced.

Therefore, an object of the present invention is to utilize the excellent hydraulic properties of calcium-containing materials such as granulated blast furnace slag, while exhibiting sufficient strength, while having a high molar ratio.
It is to improve the permeability as compared with.

[0010]

[Means for Solving the Problems] The above problem is that the content of calcium oxide is 20 to 50% by weight,
0% or more is glassy, and the Blaine value was obtained by suspending calcium oxide-containing fine powder having a Blaine value of 5000 cm ² / g or more , concentration 10
0-500 relative kg / m ³ of suspension containing calcium oxide fine powder Nigoeki, by reacting with silica or alkali silicate and sodium hydroxide, as hereinbefore 1-14 days allowed to stand aging, and SiO ₂ / The problem can be solved by using an active liquid having a Na ₂ O molar ratio of 1.45 or less in an amount of 10 to 100 liters per 100 kg of the calcium oxide-containing suspension as a main ingredient.

In this case, one or more gelling retarders selected from the group consisting of sodium carbonate, sodium bicarbonate and sodium phosphate can be further added.

Further, groundwater near the coast can be used as a medium for dispersing the calcium oxide-containing suspension.

[0013]

According to the present invention, a calcium oxide-containing substance,
For example, when an active liquid is added to a fine powder of granulated blast furnace slag, latent hydraulicity is developed by its sodium.

In this case, even when the vitrification ratio of the granulated blast furnace slag is low, unlike the case of simply unactivated water glass or other alkali, the use of the above-mentioned activated liquid makes it possible to use the granulated blast furnace slag. Ca ²⁺ can be withdrawn from and can be hardened by condensation. At this time, if water containing a large amount of electrolyte, such as groundwater near the coast, is used as the water, the salted-out silicate nuclei fill the voids around the granulated blast furnace granulated slag particles formed in the voids of the soil particles. It enhances water stopping property and stimulates latent hydraulicity of granulated blast furnace slag to increase the strength of the solidified body.

In particular, in the present invention, since the SiO ₂ / Na ₂ O molar ratio is remarkably small at 1.45 or less,
Maintains sufficient strength development compared to high molar ratio
While having good permeability.

[0016]

The present invention will be described in more detail below.

In the present invention, the content of calcium oxide is 2
0 to 50% by weight, 50% or more, preferably 90% or more of the internal structure is glassy, and the Blaine value is 5000 cm.
^Use fine powder of ² / g or more. As a typical example, fine powder of granulated blast furnace slag can be mentioned, and other metallurgical slag 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. Coarse particles have poor permeability to the ground. Even if the Blaine value is higher, improvement in permeability cannot be expected so much, and the cost required for pulverization increases.

For this type of slag, silica or alkali silicate is reacted with sodium hydroxide to give 1 to
After aging for 14 days, an active solution having a SiO ₂ / Na ₂ O molar ratio of 1.45 or less, more preferably 1.30 or less, is added. The molar ratio in the technique described in the above publication is 1.5 to
It is 2.5, which is large. When the molar ratio is high, the permeability and the like are poor, as will be shown in Examples described later. Except for this molar ratio, a detailed description of the characteristics of the active liquid and the like is known from the above-mentioned publications and the like, and will not be described in detail here.

The blending amount of the improving agent according to the present invention is 100 to 50, which is obtained by suspending fine powder containing calcium oxide.
For a suspension containing 0 kg / m ³ of calcium oxide fine powder,
The active solution is 10 to 10 per 100 kg of suspension containing calcium oxide.
It is added at a rate of 0 liter.

Further, one or more gelling retarders selected from the group consisting of sodium carbonate, sodium bicarbonate and sodium phosphate can be added. The amount of the gelation retarder added may be 0.2 to 10 kg / m ³ .

The ground improvement agent according to the present invention is usually prepared by mixing each material in advance and applying it to the target ground with one liquid, for example, injecting it into the ground through an injection pipe. The suspension liquid and the active liquid can be separately fed to the injection pipe, and can be mixed together in the injection pipe or in the ground. in this case,
A gel retarder can be added to one solution. Furthermore, the ground improvement agent according to the present invention can be used not only for grout injection but also for other methods such as a stirring and mixing method.

[Examples] [0023] The effects of the present invention will be clarified by showing examples below.

(Example 1) A fine powder of granulated blast furnace slag (Blaine value: 10000 cm ² / g) ,
To the 200 kg / m ³ suspension, active liquids having different molar ratios were added in various amounts, and gel time and permeability were examined. In the permeation experiment, one-liquid injection was performed at an injection pressure of 0.1 kg / cm ² into a mold filled with Toyoura standard sand through an injection pipe (filling density 1.63 g / cm ³ ). The results are shown in Table 1. At the same time, two-dimensional injection was performed on the same mold, and the strength (q ^u ₂₈ ) and hydraulic conductivity (K ₂₈ ) after 28 days were injected.
The results of the examination are also shown in the same table.

[0025]

[Table 1]

The correlation between the molar ratio of the active solution and the permeation distance is shown in FIG.

[0027] From these results, less active liquid molar ratio, the more the addition amount is small, permeability Ri heightened, whereas the intensity
Was found to decrease on the contrary.

Example 2 The results of changing the granulated blast furnace slag amount with the molar ratio of the active liquid being 1.0 are shown in Table 2. It can be seen that the granulated blast furnace slag amount hardly affects the permeability. Table 2 also shows the results of changing the Blaine value of the granulated blast furnace slag. The larger the Blaine value, the better the permeability.

[0029]

[Table 2]

Example 3 A suspension of 200 kg / m ^{3 of} granulated blast furnace slag and 400 liters / m ^{3 of} an active solution having a molar ratio of 1.3 was added with 0.5 kg of sodium phosphate as a gel time retarder. , Figure 1
As shown in, the gelation time was definitely changed. The same was true when the same amount of sodium carbonate or sodium bicarbonate was added.

[0031]

As described above, according to the present invention, the excellent hydraulic properties of calcium-containing materials such as granulated blast furnace slag are utilized, while sufficient strength is exhibited, and the molar ratio is high.
It can be improved permeability compared to that.

[Brief description of drawings]

FIG. 1 is a strength change graph when a gelation retarder is added.

FIG. 2 is a correlation diagram between the molar ratio of the active liquid and the permeation distance.

Claims (3)

(57) [Claims] 1. A calcium oxide-containing fine powder having a calcium oxide content of 20 to 50% by weight, 50% or more of the internal structure being vitreous, and a Blaine value of 5000 cm ² / g or more.
The obtained suspension, with respect to the calcium oxide powder containing suspension concentration 100 ~500 kg / m ^3, a silica or silicate alkaline with sodium hydroxide by reacting 1 to 14 days allowed to stand aging And also SiO ₂
A ground improvement agent, characterized in that an active liquid having a molar ratio of / Na ₂ O of 1.45 or less is contained in an amount of 10 to 100 liters per 100 kg of the calcium oxide-containing suspension as a main agent. 2. The ground improvement agent according to claim 1, further comprising one or more gelation retarders selected from the group consisting of sodium carbonate, sodium bicarbonate and sodium phosphate. 3. The ground improvement agent according to claim 1, wherein groundwater near the coast is used as a medium for dispersing the calcium oxide-containing suspension.