JP2860717B2 - 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. Explaining this phenomenon, as shown in FIG. 1, when slag particles come into contact with an alkaline solution,
O ₂ and Al ₂ O ₃ are 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. In this case, the higher the alkali concentration, the more the hydrolysis is promoted, but the resilience of the slag particles is reduced, the viscosity of the suspension is increased, and not only the handling but also the permeability to the target ground is reduced. Invite.

[0007] Accordingly, an object of the present invention is to obtain a ground improvement agent that utilizes the excellent hydraulic properties of calcium-containing substances such as granulated blast furnace slag, suppresses the increase in viscosity thereof, and penetrates well into the ground. It is in.

[0008]

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% is glassy, and Blaine value 5000 cm ²
A soil improver characterized by using a fine powder of / g or more, sodium hydroxide, and a divalent carbonate as main agents for the reaction.

The amount of the fine powder is 200 to 500 kg /
It is preferable that the content of sodium hydroxide is 200 to 500 liter / m ³ and the content of carbonate is 3 kg / m ³ or more based on m ³ and 10% concentration. It is also preferable to add a ligninsulfonic acid-based dispersant in an amount of 0.5 to 1.5% by weight based on the fine powder together with the carbonate.

[0010]

The point of the present invention is that divalent carbonate is used.
There is. For example a monovalent carbonates, with the addition of Na ₂ CO ₃
Also , as shown in FIG. 2, this acts as a deflocculant for dispersing the slag particles and suppresses agglomeration. Further, it reacts with water to produce Na ₂ CO ₃ + H ₂ O → NaOH + H ₂ CO ₃ (1). Furthermore, the generated H ₂ CO ₃ is contained in the slag particles.
Reacts with Ca and Ca ²⁺ to produce Ca (OH) ₂ . The Ca (OH) ₂ causes the slag to harden over a long period of time. Therefore, the increase in grout viscosity is suppressed,
It is excellent in permeability and develops strength over a long period of time.

However , monovalent carbonates such as Na ₂ CO ₃
Due to the high solubility, the reaction with the slag particles is rapid, and the aggregation suppression time for the slag particles is short. On the other hand, when a divalent carbonate such as CaCO ₃ is added as in the present invention, as shown in FIG. 3, CaCO ₃ + NaOH → Na ₂ CO ₃ + Ca (OH) ₂ . ... (2) made reaction occurs, Na ₂ CO ₃ acts as a dispersing peptizer for slag particles, although to suppress an increase in viscosity, JP
In the case of divalent carbonate, the reaction of (2) is slow,
Dispersible deflocculation lasts longer than that of monovalent carbonates . Therefore, the permeability of the grout into the ground becomes better. Moreover, the generated Ca (OH) ₂ promotes hardening of the slag particles for a long time, and has an effect of increasing the strength.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail. 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, and other alkalis have problems in strength and economy.

Further, a divalent carbonate is added. As described above, in the case of a monovalent carbonate, since the reaction is rapid, there is a tendency that the permeability associated with the increase in viscosity is not sufficient. In contrast, divalent carbonates such as CaCO ₃ and MgCO
₃ is preferable for the reason described in the above-mentioned section of operation. CaCO ₃ -MgCO ₃ (dolomite) containing both divalent carbonates can also be used. Of course, a monovalent carbonate and a divalent carbonate can be used in combination. The divalent carbonate, calcium carbonate is optimal.

The amount of the improver of the present invention is as follows: 200-500 kg / m ^{3 of} the fine powder, 200-500 liter / m ^{3 of} sodium hydroxide and 3 kg / m ³ of carbonate at 10% concentration.
^It is preferred that the number be ³ or more. Fine powder is caused a curing reaction by a small amount of sodium hydroxide, as shown in FIG. 4, preferably contained in terms of early development of strength 200 l / 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 liter / m
^3. Addition of at least 3 kg / m ³ as a divalent carbonate is desired in order to expect the effects of the present invention. As a dispersant for the granulated blast furnace slag fine powder, a ligninsulfonic acid-based or naphthalene-based dispersant can be used in combination with a divalent carbonate.

The soil improver according to the present invention can be prepared by mixing each material in advance and applying it to the target ground as a single solution. For example, it can be injected into the ground through an injection pipe. And the sodium hydroxide solution can be separately fed to an injection tube and combined and mixed in the injection tube or in the ground.
In this case, the carbonate can be added to one of the liquids.
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. ( Comparative Example ) Fine powder of granulated blast furnace slag (Brain value 12000cm ² / g) 3
Under 00kg / m ³ relative to the concentration of 10% formulation of sodium hydroxide is added 350 l / m ^3, and the amount of sodium carbonate Na ₂ CO ₃ (monovalent carbonate) while varying the viscosity Was examined for changes. Table 1 shows the results. further,
Kneading time for each amount of sodium carbonate added
Was set to 30 minutes, and Toyoura standard sand was filled with an injection tube.
Injection pressure 1kg / cm for mold (5mmφ × 100cm)
Table 1 shows the results of one-solution injection in Table 2 and the examination of the permeability.
It was also described in.

[0019]

[Table 1]

From these results, it can be seen that the addition of sodium carbonate can suppress the increase in viscosity over time, but the addition of 30 kg / m
³ or the addition result, it can be seen that the effect is reduced. What
Note that the penetration distance is the same as when the following bivalent carbonate is used.
50 cm was achieved when the amount of sodium carbonate added was 5
It was only the formulation of test No. 2 which was kg / m3.

(Example 1) In a comparative example , a similar test was conducted by adding a divalent carbonate and calcium carbonate CaCO ₃ instead of a monovalent carbonate and sodium carbonate. Table 2 shows the results. In this case,
The effect of suppressing the increase in viscosity and improving the permeability was observed at all the addition amounts of 3 kg / m ³ or more. In addition, the effect is one
It was also found to be larger than that of sodium carbonate, which is a monovalent carbonate .

[0022]

[Table 2]

(Example 2 ) Table 3 shows the results of viscosity, penetration distance after 30 minutes and strength after 28 days when other divalent carbonates were used.

[0024]

[Table 3]

(Example 3 ) Table 4 shows the results obtained when the amount of sodium hydroxide added to the granulated blast furnace slag powder was changed.

[0026]

[Table 4]

From these results, it was found that the strength was slightly increased as the amount of sodium hydroxide added was increased, and the strength was sharply increased as the added amount of the granulated blast furnace slag powder was increased. Furthermore, it is difficult to uniquely determine which composition is preferable in terms of the target ground and the objective improvement effect, but the above-described composition is generally preferable.

[0028]

As described above, according to the present invention, while utilizing the excellent hydraulic property of calcium-containing substances such as granulated blast furnace slag, the rise of the viscosity is suppressed, and the ground that penetrates well into the ground An improver can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a reaction mechanism by adding sodium hydroxide to granulated blast furnace slag particles.

FIG. 2 is an explanatory diagram of a reaction mechanism by adding sodium hydroxide and sodium carbonate to granulated blast furnace slag particles.

FIG. 3 is an explanatory diagram of a reaction mechanism by adding sodium hydroxide and calcium carbonate to granulated blast furnace slag particles.

FIG. 4 is a graph showing changes over time in viscosity and strength depending on the amount of sodium hydroxide added.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomoyuki Sekiguchi 4-35, Kudankita, Chiyoda-ku, Tokyo Light Industry Co., Ltd. (56) References JP-A-2-107542 (JP, A) (58) Field surveyed (Int.Cl. ⁶ , DB name) C09K 17/02 C04B 28/08 C09K 17/06 E02D 3/12 101

Claims (3)

(57) [Claims] 1. The method according to claim 1, wherein the content of calcium oxide is 20 to 50% by weight, and 90% or more of the internal structure is glassy .
One Blaine value and fine powder of more than 5000 cm ² / g is sodium hydroxide, soil improvement agent, characterized in that the base compound of reacting a divalent carbonate. 2. A fine powder ^{200 ~500 kg / m 3, 10} % sodium hydroxide at a concentration reference is from 200 to 500 liters / m ^3, two
The soil improver according to claim 1, which contains ³ kg / m ³ or more of a monovalent carbonate. 3. The soil improver according to claim 1, wherein the ligninsulfonic acid-based dispersant is added in an amount of 0.5 to 1.5% by weight based on the fine powder.