JP2959706B2 - Ground improvement agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a ground improving agent 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.

On the other hand, for the purpose of obtaining a high strength, a suspension type or a semi-suspension type is widely used.

[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 present applicant previously disclosed in Japanese Patent Application Laid-Open No. 4-293994, while utilizing the excellent hydraulic property of calcium-containing materials such as granulated blast furnace slag, as well as permeability and after a long time. As a soil improver with excellent strength, the content of calcium oxide is 20 to 50% by weight.
90% or more of the internal structure is glassy, and a fine powder having a Blaine value of 5000 cm ² / g or more, sodium hydroxide or potassium hydroxide, and a BET surface area of 40 m ² / g.
We have proposed a ground improver mainly composed of g or more of white carbon.

[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 .

However, although high strength is usually preferable, ground improvement by grouting is often used as temporary work, and after this work, the ground once reinforced may be excavated. In the case of such an application, it is not preferable that the strength increases unitarily or linearly with the passage of time, and after a certain time, the strength does not further increase or even if it increases, the gradient is gentle. desired.

Accordingly, it is an object of the present invention to ensure that the strength is sufficient for practical use, and that the strength does not increase so much due to aging.

In order to solve this problem, the present applicant has disclosed in
In JP-A-41533, an admixture which is a mixture of limestone and clay fine powder is added to the material system,
The one that suppresses the development of strength was proposed earlier.

However, the clay component of the admixture is obtained through a special process, and not only causes a cost increase but is not easily available or generally available.

Accordingly, a main object of the present invention is to solve the above-mentioned problems while using a material which can be easily and inexpensively obtained as a material for suppressing the development of strength.

[0013]

The ground improving agent of the present invention which has solved the above-mentioned problems has a calcium oxide content of 20 to 5%.
0% by weight, 90% or more of the internal structure is vitreous, and a fine powder having a Blaine value of 5000 cm ² / g or more, an alkali stimulant, and calcium carbonate as main components. It is characterized by being 35 to 90% by weight with respect to the powder.

Here, the alkali stimulant can be selected from one or more selected from the following groups. (1) Sodium (2) Sodium (4) sodium carbonate potassium hydroxide (3) aluminate hydroxide, at least one (5) the molar ratio of SiO ₂ / Na ₂ O potassium carbonate, carbonates consisting of sodium carbonate, potassium Is a non-colloidal and ionic activated water glass having a value of 2.5 or less. Further, as the calcium carbonate, those having the following composition can be used. _{Ig.loss: 43.0 ~45.0% SiO 2:} 1.0% or less Al ₂ O _3: 0.2% or less Fe ₂ O _3: 0.3% or less CaO: 54.5 ~55.5% MgO: 0.5 % or less also further, BET surface area of 40 m ² / G or more of white carbon.

Specifically, the fine powder is composed of 20
0-500 kg / m ³ , 200% -500 liters / m ³ sodium hydroxide and 1% white carbon based on 10% concentration
And 0.01 to 1.0 wt% with respect to 0% sodium hydroxide solution, 50 calcium carbonate acid to the fine powder
To 90%.

The white carbon is composed of silicic anhydride,
One or more selected from the group consisting of hydrous silicic acid, hydrous calcium silicate, and hydrous aluminum silicate can be used.

[0017]

The blast furnace (water granulated) slag fine powder can be used as the fine powder according to the present invention.

[0018] For this slag particles, sodium hydroxide stimulates For example alkali stimulant, CaO-MgO-Al ₂ O
_A hydration product of _3- nH ₂ O is formed. Calcium carbonate reacts with alkali as follows. The reaction of CaCO ₃ + NaOH → Ca (OH) ₂ + Na ₂ CO ₃ takes place in a chain, and the fine particles of calcium silicate generated by the pozzolanic reaction effectively intervene between the slag particles to ensure the strength. .

Meanwhile, if you do not want an increase in strength as described above, it is conceivable to reduce the amount of slag, with respect to the soil 1 m ³ in case porosity of 40%, the amount of slag e.g. In the case of 350 kg / m ³ , the gap filling rate is 59% and the 28-day compressive strength is 50 kgf / m ³ , whereas in the case of a slag amount of, for example, 200 kg / m ³ , the gap filling rate is Is 34% and the compression strength on 28th is 0-4kgf
/ M ³ and not suitable for extremely reduced practicality. Therefore, with the improved material proposed in JP-A-4-293994, 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 calcium carbonate 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. Moreover, according to JP-A-6-41533,
Compared to the case where an admixture, which is a mixture of limestone and clay fine powder, is added, the same effect of suppressing the development of strength and the required strength can be secured.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. In the present invention, the content of calcium oxide is 20 to 5
0% by weight, 90% or more of the internal structure is vitreous, and a fine powder having a Blaine value of 5000 cm ² / g or more is used. As a typical example thereof, fine powder of granulated blast furnace slag can be mentioned. Other metallurgical slags can also be used. The content of calcium oxide in the fine powder is more preferably 25 to 35% by weight. The Blaine value is more preferably 8,000 to 16000 cm ² / g in terms of permeability.
It is. In the case of coarse particles, permeability to the ground is poor. Although the Blaine value can be used up to about 20,000 cm ² / g, even if it is higher than this, improvement in permeability cannot be expected so much, and the cost required for pulverization is increased.

An alkali stimulant 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, the molar ratio of at least one of sodium aluminate, sodium carbonate, potassium carbonate, and sodium / potassium carbonate, SiO ₂ / Na ₂ O, is 2.5 or less, more preferably 1.45 or less. The non-colloidal and ionic activated water glass can be used as well.

The activated water glass will be described. Normal water glass, for example, No. 3 water glass specified in JIS, is colloidal and nonionic. On the other hand, water glass and sodium hydroxide are brought into contact with each other and activated and contacted according to the equations (1) and (2) on page 2 of JP-B-2-36155. It is glass.

[0024] When activated water glass liquid is added to the fine powder of granulated blast furnace slag, latent hydraulicity is exhibited by its sodium. In this case, even when the vitrification rate of the fine powder of the granulated blast furnace slag is low, unlike normal water glass or other alkali that is not activated, Ca ²⁺ It can be withdrawn and hardened by setting. In addition, it shows very good permeability.

Further, fine white carbon can be added in the present invention. As the fine white carbon, one or two or more selected from the group consisting of silicic anhydride, hydrous silicic acid, hydrous calcium silicate, and hydrous aluminum silicate can be used. The BET surface area is 40 m ² / g or more, preferably 50 to 30 m ² / g.
Those having 0 m ² / g can be suitably used. In addition, hydrous calcium silicate is desirable because it delays the rate of hydrolysis of slag particles by an alkaline solution, so that the gel time can be easily adjusted.

Further, as the calcium carbonate in the present invention, those having the above-mentioned composition can be used. In this case, the average particle size of calcium carbonate is 1 to 5 μm.
m, a maximum of 15 μm (5,000 to 50,000 cm ² /
g) Fines are preferred.

The preferred formulation of the soil conditioner according to the present invention is as follows:
200-500 kg / m ^{3 of} calcium oxide-containing fine powder, 1
Based on 0% concentration, sodium hydroxide is 200 to 500 liter / m ³ , white carbon is 0.01 to 1.0% by weight based on 10% sodium hydroxide solution, and the calcium carbonate is based on fine powder. 35-90% by weight
(Particularly preferably 50 to 80% by weight).

The fine powder causes a curing reaction even with a small amount of an alkali stimulant, but it is necessary to add a required amount of the alkali stimulant in view of early development of strength. It is preferable that the content be 1 liter / 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%, 400 to 1000 liters /
the m ^3. The amount of the white carbon fine particles is desirably 0.01% by weight or more in order to exhibit the effect. Conversely, if the amount is excessively large, the gel time will be shortened and the permeability will be impaired. Calcium carbonate is desirably 35% by weight or more based on the fine powder.
If it is less than 35% by weight, the strength tends to be excessive. 8
If it exceeds 5% by weight, the desired strength cannot be obtained.

In the soil conditioner according to the present invention, 25 kg of 7000-10000 cm ² / g cement is further added.
/ M ³ or less. The compounding of this cement has the function of ensuring solidification in the entire infiltration area.

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 alkali stimulant, such as sodium hydroxide solution, can be fed separately to the injection tube and combined and mixed 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.

[0031]

EXAMPLES Examples will be shown below to clarify the effects of the present invention. (Comparative Examples 1 and 2, Examples 1-6) relative to the chemical 1 m ^3, the fine powder of granulated blast furnace slag (Blaine value 15000 cm ² /
g: the content of calcium oxide is 20 to 50% by weight, and 90% or more of the internal structure is glassy) of 350 kg /
Based on m ³ and a basic blend of 10% sodium hydroxide at a concentration of 350 l / m ³ , the 28-day compressive strength, the change in viscosity over time, and the penetration distance by a penetration test were examined (Comparative Example 1). In the experiment, the kneading time was set to 10 minutes,
Mold filled with Toyoura standard sand using an injection pipe (diameter 5m)
(mφ × length 100 mm) with one injection at an injection pressure of 1 kg / cm ² .

In Comparative Example 1, similar properties were examined by substituting a part of the amount of the fine powder with calcium carbonate having the above composition (Comparative Example 2 and Examples 1 to 6). The results are shown in Table 1, FIG. 1 and FIG.

[0033]

[Table 1]

From these results, although the viscosity change and the permeability are not much different from each other, the strength is remarkably changed by blending calcium carbonate. Generally, when used for temporary construction, the compressive strength on 28 days is 20 kgf / cm.
² below (optionally up to about up to 25 kgf / cm ² may be allowed), and is preferably 15 kgf / cm ^2. On the other hand, if the strength is excessively low, there is no effect of strengthening the target ground. Therefore, it is understood that the amount of calcium carbonate is desirably 35 to 90% by weight, particularly 50 to 80% by weight.

(Examples 7 to 11) The fine powder of Example 3 was replaced with 1
75 kg / m ^3, and calcium carbonate on the basis of the formulation of 175 kg / m ^3, in place of the type of alkali stimulant, were examined 28 days compressive strength, with the results shown in Table 2. Table 2 also shows the results of Example 3.

[0036]

[Table 2]

According to Table 2, the same curing can be achieved with the indicated alkali stimulants. In addition, although the penetration distance is not shown, it is substantially the same as that of Example 3 and shows excellent permeability.

(Examples 12 to 16 and Reference Example) White carbon (hydrous silicic acid) and cement (9000 cm ² / g) were added to the composition of Example 3, and the effect of the addition was examined. Further, the effect of the Blaine value was examined by changing the Blaine value of the fine powder of Example 3. Table 3 shows the results.

[0039]

[Table 3]

From these results, it is found that the addition of white carbon improves permeability and strength. It can be seen that the addition of cement shows a tendency for the permeability to deteriorate, but the effect of improving the strength increases.

[0041]

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 added amount of an alkali stimulant.

FIG. 2 is a bar graph of the results of a study on permeability due to the addition of an alkali stimulant.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Daniel Gvano, France 92110 Chrys Allegan Vetta 1 (72) Inventor Ubert Batmon, France 92000 Nanterre City, Wattfall Avenue 6 Sole Tanche Enterprise (56) References JP JP-A-4-293993 (JP, A) JP-A-2-107542 (JP, A) JP-A-6-41533 (JP, A) Tables JP-A-2-503689 (JP, A) (58) Fields investigated (Int) .Cl. ⁶ , DB name) C09K 17/02 C09K 17/06 C09K 17/12 E02D 3/12 101

Claims (5)

(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 5000 cm ² / g or more; an alkali stimulant; A soil improver comprising calcium as a main material, and the calcium carbonate is 35 to 90% by weight based on the fine powder. 2. The soil conditioner according to claim 1, wherein said alkali stimulant comprises at least one member selected from the following group. (1) Sodium (2) Sodium (4) sodium carbonate potassium hydroxide (3) aluminate hydroxide, at least one (5) the molar ratio of SiO ₂ / Na ₂ O potassium carbonate, carbonates consisting of sodium carbonate, potassium Non-colloidal and ionic activated water glass having a pH of 2.5 or less 3. The soil conditioner according to claim 1, wherein the calcium carbonate has the following composition. _{Ig.loss: 43.0 ~45.0% SiO 2:} 1.0% or less Al ₂ O _3: 0.2% or less Fe ₂ O _3: 0.3% or less CaO: 54.5 ~55.5% MgO: 0.5 % or less 4. The soil conditioner according to claim 1, further comprising white carbon having a BET surface area of 40 m ² / g or more. 5. The method according to claim 1, wherein the fine powder is 200 to 500 kg / m ³ ,
% Of sodium hydroxide is 200 to 500 liter / m ³ , white carbon is 0.01 to 1.0% by weight based on 10% sodium hydroxide solution, and the admixture is 50% based on fine powder. The soil conditioner according to claim 1, wherein the content of the soil conditioner is from 80 to 80% by weight.