JP3453156B2 - Ground injection agent and soil hardening method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a specific composite oxide sol composed of silica and other inorganic oxides, a ground injecting agent containing the hardening agent thereof, and a method for hardening soil.

[0002]

2. Description of the Related Art The ground injection agent containing water glass as a main ingredient is not suitable for the ground salt that is contaminated with the alkaline salt in the water glass (so-called alkali pollution) or desiliconization occurs. Since there is also a problem in durability, various ground injection agents mainly containing silica sol containing no alkali salt have been proposed recently.

For example, Japanese Unexamined Patent Publication No. 54-73407 and Japanese Unexamined Patent Publication No. 59-93787 disclose a ground injection agent containing silica sol as a main component in which sodium ions are reduced to a predetermined content. . In addition, JP-A-58
JP-A-103586 discloses a ground injection method using a curing agent containing no sodium or potassium.

However, all of the above-mentioned inventions still have room for improvement in that the curing (gelling) speed of the injectable agent is fast and not suitable for ground injection work, or that the curing strength is weak and reliability is poor. It is the actual situation that has been done.

[0005]

OBJECT OF THE INVENTION The object of the present invention is to prevent the contamination of groundwater and soil due to the outflow of the alkali salt in the infusate, and to control the curing speed easily, and to provide the ground having excellent curing strength and durability. An object is to provide an injectable agent and a soil hardening method.

[0006]

SUMMARY OF THE INVENTION The ground injection agent according to the present invention is a sol in which fine particles of a composite oxide composed of silica and one or more kinds of inorganic oxides other than silica are dispersed, and the average particle size of the fine particles. A composite oxide sol whose diameter (Dp) and specific surface area (S) satisfy the inequality S (m ² / g) ≧ 3000 / Dp (nm) is used as a main component, and a curing agent is contained therein.

The soil hardening method according to the present invention is a sol in which fine particles of a composite oxide consisting of silica and one or more inorganic oxides other than silica are dispersed, and the average particle size of the fine particles is Characterized by mixing a complex oxide sol whose diameter (Dp) and specific surface area (S) satisfy the inequality S (m ² / g) ≧ 3000 / Dp (nm) with a curing agent and injecting it into the ground It is what

[0008]

DETAILED DESCRIPTION OF THE INVENTION The above composite oxide is a composite oxide composed of silica and an inorganic oxide other than silica, and is not a mixture of the respective oxides. As the inorganic oxide, there are 3A group, 3B group, 4A group, 4B group and 5A of the periodic table.
Examples thereof include oxides of metals or non-metal elements of Group 5B, 6A, and specifically, Al ₂ O ₃ and B.
₂ O ₃ , TiO ₂ , ZrO ₂ , SnO ₂ , Ce ₂ O ₃ ,
_{P 2 O 5, Sb 2 O} 5, there is MoO _3, WO ₃ and the like.

The composite ratio (molar ratio) of silica to the above-mentioned inorganic oxide is suitably in the range of 0.5 to 20. If this ratio exceeds 20, the specific surface area of the fine particles to be described later becomes small, while if it is less than 0.5, the specific surface area of the fine particles hardly increases. In addition, the stability of the composite oxide sol becomes poor.

The complex oxide sol used in the present invention has a specific surface area S of fine particles of complex oxide dispersed in the sol.
(M ² / g) is characterized by a large value. Specifically, when the average particle size of fine particles is expressed by Dp (nm), the inequality S (m ² / g) ≧ 3000 / Dp (nm) A sol in which satisfying fine particles are dispersed. In particular, it is desirable that the specific surface area S is 500 m ² / g or more and that S (m ² / g) ≧ 6000 / Dp (nm).

Such a complex oxide sol comprises, for example, an alkali metal, ammonium or organic base silicate,
It can be produced by simultaneously adding an alkali-soluble inorganic compound to an alkaline aqueous solution having a pH of 10 or more and producing colloidal particles without controlling the pH of the reaction solution.

As a raw material of silica, a silicate of alkali metal, ammonium or organic base is used. As the alkali metal silicate, sodium silicate (water glass) or potassium silicate is used. Examples of the organic base include quaternary ammonium salts such as tetraethylammonium salt, amines such as monoethanolamine, diethanolamine and triethanolamine. For ammonium silicate or organic base silicate, silicic acid solution is used. In addition, an alkaline solution obtained by adding ammonia, a quaternary ammonium hydroxide, an amine compound or the like is also included.

Further, as a raw material of the inorganic oxide, an alkali-soluble inorganic compound is used, and the alkali metal salt or alkaline earth metal salt, ammonium salt of the above-mentioned metal or non-metal oxo acid (oxy acid), ammonium salt, A quaternary ammonium salt can be mentioned. More specifically, sodium aluminate, sodium tetraborate, zirconyl ammonium carbonate, potassium antimonate, potassium stannate, sodium aluminosilicate, sodium molybdate, cerium ammonium nitrate, and sodium phosphate are suitable.

In order to form the complex oxide sol, an alkaline aqueous solution of the compound is individually prepared in advance, or
Alternatively, a mixed aqueous solution is prepared in advance, and this aqueous solution is gradually added to an alkaline aqueous solution having a pH of 10 or more while stirring, depending on the composite ratio of the target complex oxide. Although the pH value of the aqueous solution changes at the same time as the addition of these aqueous solutions, an operation for controlling the pH value within a predetermined range is not particularly necessary. The aqueous solution finally settles to a pH value determined by the type of inorganic oxide and its composite ratio.

When the pH is controlled within a predetermined range, for example, an acid may be added. In this case, the added acid forms a metal salt of the raw material of the complex oxide, and thus the stability of the sol. May decrease. There is no particular limitation on the addition rate of the aqueous solution at this time.

It is also possible to produce the composite oxide sol by using a dispersion liquid of seed particles as a starting material.
In this case, as seed particles, SiO ₂ , Al ₂ O
Fine particles of an inorganic oxide such as ₃ , TiO ₂ or ZrO ₂ or a composite oxide of these are used, and normally, a sol thereof can be used. Of course, the composite oxide sol obtained by the above manufacturing method may be used as the seed particle dispersion liquid. The colloidal particles of the obtained composite oxide sol have a large specific surface area, unlike the colloidal particles obtained by the conventional method, and thus are porous.

It is desirable that the solid content concentration of the composite oxide sol is finally adjusted to a range of 5 to 50% by weight. At this time, when the complex oxide sol is concentrated to a desired concentration, it is better to concentrate the complex oxide after removing some of the alkali metal ions, alkaline earth metal ions, ammonium ions, etc. in the dispersion liquid in advance. A stable concentrated sol in which fine particles are dispersed can be obtained. As a removing method, a known method such as ion exchange resin or ultrafiltration can be adopted.

In the present invention, the curing agent means a substance which causes gelation when mixed with the complex oxide sol.
Such curing agents include carbonates, sulfates, hydrochlorides,
Inorganic salts such as nitrates, phosphates, silicates, specifically,
CaCO ₃ , CaSO ₄ , CaCl ₂ , Ca (NO ₃ )
₂ , Ca ₃ (PO ₄ ) ₂ , CaSiO ₃ , MgCO ₃ ,
MgSO ₄ , MgCl ₂ , Mg (NO ₃ ) ₂ , Mg
₃ (PO ₄ ) ₂ , MgSiO ₃ , Al ₂ (SO ₄ ) ₃ ,
K ₂ SO ₄ , Na ₂ SO ₄ , or H ₂ SO ₄ , H
Mineral acids such as NO ₃ , HCl and H ₃ PO ₄ , organic acids such as lactic acid, humic acid and oxalic acid, aggregating agents such as polyaluminum chloride, metal-containing complexes, cements and the like can be mentioned.
Particularly preferred curing agents include CaCl ₂ and Na ₂ S
O ₄ , lactic acid, humic acid, polyaluminum chloride, cement, aluminate, etc. are used.

In the ground injection material of the present invention, the amount of the curing agent with respect to the composite oxide in the composite oxide sol is 0.0 by weight.
It is preferably in the range of 5-10. If the amount of the curing agent is less than 0.05, the curing (gelling) rate of the composite oxide sol will be extremely slow and the curing strength will be weak, which is not desirable. On the other hand, if it is more than 10, the curing (gelling) speed becomes very fast, which causes inconvenience such as the start of curing before the completion of ground injection, and the curing strength becomes weak, which is not desirable.

In the present invention, it is possible to control the curing speed by selecting an appropriate curing agent and adjusting the amount thereof. That is, for example, if the amount of the curing agent is increased, the curing speed will be increased. The amount of the curing agent with respect to the complex oxide in the preferable complex oxide sol is selected in the range of 0.3 to 3.0. It is also possible to control the curing speed by using one or more curing agents.

The above-mentioned curing agent is dissolved in water, an acid, or an alkaline aqueous solution, or is mixed in a powder state with the above-mentioned composite oxide sol. The mixing is usually performed at the construction site of the injection work, and when the mixture is injected into the ground, the curing agent may be dispersed in the complex oxide sol. Due to the construction work, this ground injection material has a solid content of 20 to 40% by weight.
It is desirable to be in the range of. Further, it is effective when used in combination with cement or the like, and when an acidic curing agent is used, some of the constituent components of the composite oxide particles are eluted and gelled, so that the curing strength is further increased.

Since the ground injecting agent of the present invention has a large specific surface area and a porous composite oxide sol as a main component, it has an alkali metal, an alkaline earth metal or the like as compared with the case of using conventional water glass. There is little outflow. This is because the complex oxide sol has a high ability to capture these metals,
This is because the metal ions are strongly adsorbed on the solid acid points of the composite oxide particles and desiliconization does not easily occur. Further, it has a feature that the curing strength is high as compared with the conventional silica sol.

Further, this ground injecting agent is easier to control the curing (gelling) rate as compared with the case of using a conventionally known silica sol. Curing (gelation) occurs by neutralizing the surface charge of colloidal particles with a curing agent, but the colloidal particles of the complex oxide sol have a large specific surface area, and the surface charge is neutralized compared to conventional silica sols. Is unlikely to occur with a small amount of curing agent. This is because the colloidal particles are porous, so that the curing agent is adsorbed inside the particles and gelation is relaxed. Therefore, in the present invention, the curing (gelation) rate can be controlled by adjusting the amount of the curing agent.

[0024]

【Example】

[Preparation of complex oxide sol] Preparation example 1 Silica sol 2 having an average particle size of 5 nm and a SiO ₂ concentration of 20% by weight
A mixture of 0 g and pure water 380 g was heated to 80 ° C. The pH of this reaction mother liquor was 10.5, and 1800 g of 1.5 wt% sodium silicate aqueous solution as SiO ₂ and 1800 g of 0.5 wt% sodium aluminate aqueous solution as Al ₂ O ₃ were simultaneously added to the mother liquor. . Addition speed is 5 ml
/ Min, during which the temperature of the reaction solution was maintained at 80 ° C. Immediately after the addition, the pH of the reaction solution rose to 12.5, and thereafter hardly changed. After the addition was completed, the reaction solution was cooled to room temperature and concentrated using an ultrafiltration membrane to obtain SiO ₂ · Al.
_{A 2} O ₃ composite oxide sol (a) was obtained.

Table 1 shows the specific surface area and average particle diameter of the colloidal particles dispersed in this composite oxide sol. The specific surface area is determined by the titration method [Analytical Chemistry Vol.
8, No. 12 (1956)], and the average particle size was measured by the dynamic light scattering method.

Preparation Example 2 Instead of the aqueous sodium aluminate solution of Preparation Example 1, Z
except as and rO ₂ using 0.5% by weight zirconium ammonium carbonate aqueous solution 1800g in the same manner as in Preparation Example 1, to obtain a SiO ₂ · ZrO ₂ composite oxide sol (b).
The properties of this sol are shown in Table 1.

Preparation Example 3 900 g of the aqueous sodium aluminate solution of Preparation Example 1 and Z
At the same time was added 0.5 wt% and ammonium zirconyl carbonate solution 900g as and rO _2, obtained otherwise in the same manner as in Preparation Example _{1, SiO 2 · Al 2 O} 3 · ZrO 2 composite oxide sol (c) It was The properties of this sol are shown in Table 1.

[0028]

[Table 1] Colloidal oxide concentration Colloidal particle sol ( % by weight ) Specific surface area (S ) Average particle size (Dp) S x Dp a 30 1050 (m ² / g) 20 (nm) 21000 b 20 600 15 9000 c 40 800 21 16800

The composite oxide sol of Example 1 Preparation Example 1~3 (a), (b) ,
Using (c), curing agents 1 to 8 were conducted by mixing the curing agents shown in Tables 2 and 3. That is, 100 g of the composite oxide sol is dispersed in water together with a curing agent if desired, and this dispersion is designated as solution A. On the other hand, separately, a curing agent was mixed with water to prepare a liquid B, and the liquid A and the liquid B were mixed in a polybeaker. The mixing operation was quickly performed in 1 to 3 seconds, and the time point of mixing was used as a reference for elapsed time.

The properties of the obtained mixed gel are shown in Tables 2 and 3 together with the preparation conditions. The property evaluation and measurement method of the mixed gel are as follows. (1) Strength of gel On the surface of the mixed gel in a poly beaker, an inverted triangular pyramid weight having a weight of 110 g (top surface diameter 23 mm, height 20 mm)
Was set, the distance (mm) settled in the gel was measured, and the average of three measurements was taken. In the table, ∞ indicates that the weight settled to the bottom of the beaker.

(2) Water resistance The mixed gel that had been left for 24 hours was immersed in running water, and after 30 days, the state was observed. ○ (solid state), △ (shape is retained, but touched with a finger) The state of collapse) and × (amorphous state).

Comparative Example 1 Liquid B was mixed under the conditions shown in Table 3 in the same manner as in Example 1 except that 20% by weight of water glass was used instead of the composite oxide sol of Example 1. The properties of the mixture gel are shown in Table 3.

Comparative Example 2 20 wt% silica sol (specific surface area 180 m ² / g, average particle size 15 nm) was used instead of the composite oxide sol of Example 1.
In the same manner as in Example 1 except that the above was used, the solution B was mixed under the conditions shown in Table 3. The properties of the mixture gel are shown in Table 3.

[0034]

[Table 2] Experiment 1 Experiment 2 Experiment 3 Experiment 4 Experiment 5 [Solution A] Sol aa aa aa Weight of sol (g ) 100 100 100 100 100 Curing agent -Na ₂ CO ₃ Na ₂ CO ₃ Na ₂ CO ₃ - the weight of the curing agent (g) - 20 5 5 - water content (g) 100 80 95 95 - weight of [solution B] curing agent PC PC H ₂ SO ₄ CaCl ₂ lactic curing agent (g) 100 100 16 5 30 Water content (g ) 170 170 250 265 70 [Gel strength] 10 minutes later (mm) ∞ 8 ∞ 20 30 1 day later (mm) 20 4 5 5 4 [Water resistance] ○ ○ ○ ○ ○ (Note) PC is Portland Semé Indicates the event.

[0035]

[Table 3] Experiment 6 Experiment 7 Experiment 8 Comparison 1 Comparison 2 [Solution A] Sol b cc Water glass s Weight of sol (g ) 100 100 100 100 100 Hardener Na ₂ CO ₃ CaCl ₂ CaSiO ₃ Na ₂ CO ₃ -Curing agent weight (g ) 1.6 20 1.2 1.6- Water content (g ) 100-100 100- [B liquid] Curing agent PC Lactic acid PC PC Lactic acid Curing agent weight (g ) 100 10 100 100 30 Moisture content (g) ) 170 90 170 170 70 [Gel strength] 10 minutes later (mm) 7 15 5 ∞ ∞ 1 day later (mm) 4 3 3 ∞ 50 [Water resistance] ○ ○ ○ × △ (Note) PC indicates Portland cement, s represents silica sol.

[0036]

The ground injecting agent of the present invention has a large specific surface area of dispersed fine particles and uses a complex oxide sol having a large number of pores inside the fine particles as a main agent, so that the alkaline salt in the injecting agent may flow out. It has the excellent effects that there is little contamination of groundwater and soil, less desiliconization, and high hardening strength of the injected ground. In addition, the ground injection agent has low viscosity, good permeability, and excellent water resistance and durability.

Further, in the soil hardening method according to the present invention, since the above-mentioned composite oxide sol is used as the main agent, it is extremely easy to control the hardening rate. Therefore, in combination with the simplicity of the manufacturing process of the complex oxide sol itself, it is highly practical as an industrial-scale soil hardening method, particularly as a deep soil hardening method.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-175397 (JP, A) JP-B 2-8981 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) C09K 17/00

Claims (2)

(57) [Claims] 1. A particulate of the one or a composite oxide consisting of two or more inorganic oxides other than silica and silica a monodispersed sol, average particle diameter (Dp) and the specific surface area of the fine particles ( A ground injection agent containing a curing agent and a complex oxide sol in which S) satisfies the inequality S (m ² / g) ≧ 3000 / Dp (nm). 2. A particulate of the one or a composite oxide consisting of two or more inorganic oxides other than silica and silica a monodispersed sol, average particle diameter (Dp) and the specific surface area of the fine particles ( S) is a complex oxide sol satisfying the inequality S (m ² / g) ≧ 3000 / Dp (nm) and a curing agent are mixed and injected into the ground to gel the complex oxide sol. A soil hardening method characterized by: