JP2008184502A - Hydrogel-forming material, hydrogel composition, and ground-reinforcing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogel-forming material in the form of an aqueous solution of high stability, to provide a hydrogel composition using the hydrogel-forming material, having resilience, physical strength and water resistance enough to enable ground reinforcement, and to provide a ground-reinforcing method using the hydrogel composition. <P>SOLUTION: The hydrogel-forming material is in the form of an aqueous solution containing a non-ammonium type titanium peroxo compound and polyvinyl alcohol. In the hydrogel-forming material, it is preferable that the non-ammonium type titanium peroxo compound be an alkali metal salt, the alkali metal concentration be 0.1-1.2 mass%, the polyvinyl alcohol concentration be 4-10 mass% on a solid basis, and the titanium concentration be 0.4-1.0 mass%. The hydrogel composition is such as to be obtained by incorporating the above hydrogel-forming material with a calcium aluminate compound. The ground-reinforcing method using the hydrogel composition is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydrogel-forming material, a hydrogel composition, and a ground reinforcement method mainly used in the civil engineering and construction fields.

Techniques to reduce the damage of underground structures due to earthquakes by modifying the surroundings of underground structures with elastic compositions are being studied. Further, hydrogel compositions using polyvinyl alcohol as an elastic composition have been studied (Patent Documents 1, 2, and 3).
Moreover, the organic titanium peroxo compound of a water-soluble titanium compound and its manufacturing method are disclosed (patent documents 4 and 5).
Japanese Patent Laid-Open No. 06-207071 JP 05-117033 A JP 2005-162984 A JP 2000-159786 A JP 2004-43353 A

Since these materials are in a liquid state before gelation and can be filled into an arbitrary shape, they have characteristics not found in elastic compositions such as rubber. However, since the stability of the aqueous solution is low and the physical strength after gelation is small, the gel composition may be broken at places where a large groundwater pressure or earth pressure is applied.
The present invention provides a hydrogel-forming material with high aqueous solution stability. Furthermore, the present invention provides a hydrogel composition using a hydrogel-forming material having elasticity, physical strength and water resistance capable of ground strengthening, and a ground strengthening method using the same.

  That is, the present invention provides (1) a hydrogel-forming material, which is an aqueous solution containing a non-ammonium type titanium peroxo compound and polyvinyl alcohol, and (2) the non-ammonium type titanium peroxo compound is an alkali metal salt (1 ) Hydrogel-forming material, (3) alkali metal concentration of 0.1-1.2% by mass, polyvinyl alcohol solid content concentration of 4-10% by mass (2) hydrogel-forming material, (4) titanium concentration A calcium aluminate compound is added to the hydrogel-forming material of any one of (1) to (3), and (5) any of (1) to (4). And (6) a ground strengthening method using the hydrogel composition of (5).

  ADVANTAGE OF THE INVENTION According to this invention, the hydrogel formation material with high stability of aqueous solution can be provided. Furthermore, by filling the hydrogel composition using the hydrogel-forming material around the underground structure, the ground can be strengthened and damage to the underground structure due to the earthquake can be reduced. That is, it is possible to provide a ground strengthening method in which durability against water pressure and earth pressure is greatly improved and ammonia odor is not generated.

  The parts and% used in the present invention are based on mass unless otherwise specified.

  Polyvinyl alcohol (hereinafter abbreviated as PVA) used in the present invention is acrylic as long as it has a hydroxyl group and is substantially water-soluble, including fully saponified PVA and partially saponified PVA. Various modified PVA added with acid, crotonic acid, maleic acid, acrylamide, etc. can also be used. 500-3000 are preferable and, as for the average degree of polymerization of PVA used for this invention, 1000-2000 are more preferable. The saponification degree of PVA is preferably 80 mol% or more, more preferably 90 mol% or more. When the degree of polymerization or saponification of PVA is outside the above range, the physical strength, elasticity, and water resistance after the hydrogel composition is gelled may be affected.

  The non-ammonium type titanium peroxo compound used in the present invention can be synthesized by improving the method for synthesizing the titanium peroxo compound disclosed in JP-A Nos. 2000-159786 and 2004-43353. Various types of titanium peroxo compounds such as citric acid, malic acid, and glycolic acid are known as titanium ligands, and salts include ammonium salts, potassium salts, sodium salts, cesium salts, and rubidium salts. It is shown.

  The solid content concentration of PVA contained in the aqueous solution (hydrogel-forming material) containing the non-ammonium type titanium peroxo compound of the present invention and polyvinyl alcohol is appropriately determined depending on the application and is not particularly limited. However, it is usually preferable to be about 4 to 10%. If it is less than 4%, the elasticity of the cured product may be insufficient, and if it exceeds 10%, the viscosity of the aqueous solution may increase and precipitation may occur.

  The concentration of the alkali metal contained in the aqueous solution (hydrogel forming material) containing the non-ammonium type titanium peroxo compound of the present invention and polyvinyl alcohol is preferably 0.1 to 1.2%, and preferably 0.3 to 1.0. % Is more preferable. If it exceeds 1.2%, precipitation may occur due to the interaction with polyvinyl alcohol. If it is less than 0.1%, the time from the addition of the calcium aluminate compound to gelation may be significantly increased. The titanium concentration is preferably 0.4 to 1.0%. If it is less than 0.4%, the elasticity, physical strength and water resistance of the hydrogel composition after gelation may be insufficient, and if it exceeds 1.0%, it may be uneconomical.

The calcium aluminate compound used in the present invention is obtained by blending calcium raw materials such as limestone, lime and slaked lime, and aluminum raw materials such as bauxite and aluminum residual ash at a predetermined ratio, heat-treating, and then pulverizing.
The heat treatment temperature is preferably 1200 to 2000 ° C, and more preferably 1400 to 1600 ° C. If it is less than 1200 degreeC, a predetermined compound may not be obtained, and if it exceeds 2000 degreeC, it may become uneconomical. The atmosphere during firing may be an oxidizing atmosphere or a reducing atmosphere. Moreover, a rotary kiln, an electric furnace, etc. can be used for baking facilities.
As raw materials, in addition to CaO and Al ₂ O ₃ as main components, SiO ₂ , Fe ₂ O ₃ , MgO, TiO ₂ , P ₂ O ₅ , Na ₂ O, K ₂ O, fluorine, chlorine, heavy metals, etc. However, it is not a problem as long as the object of the present invention is not substantially hindered.

The CaO / Al ₂ O ₃ molar ratio of the calcium aluminate compound is not particularly limited, but is preferably 0.4 to 2.5. If it is less than 0.4, the compressive strength of the hydrogel composition after gelation may be low, and if it exceeds 2.5, the gelation time is shortened, so the aqueous solution and the calcium aluminate compound may not be mixed uniformly. . In addition, the hydrogel formation material of this invention exhibits alkalinity, when calcium aluminate is added and gelatinized.

The fineness of the calcium aluminate compound is preferably 1500 to 8000 cm ² / g, more preferably 3000 to 6000 cm ² / g, in terms of the specific surface area of Blaine. If the coarse particles are less than 1500 cm ² / g, sufficient strength may not be obtained, and if the fine powder exceeds 8000 cm ² / g, the reactivity may be high and sufficient pot life may not be ensured. However, this does not apply when the pot life is adjusted using an organic acid or the like.

The vitrification rate of the calcium aluminate compound is not particularly limited, and it can be used in the present invention whether crystalline or amorphous. Calcium aluminate compounds of the _{crystalline, 3CaO · Al 2 O 3,} 12CaO · 7Al 2 O 3, CaO · Al 2 O 3, 3CaO · 5Al 2 O 3, CaO · 2Al 2 O 3, CaO · 6Al 2 O ₃ etc. are mentioned. Two or more of these can be used in combination.
In the present invention, the vitrification rate was measured by the following X-ray diffraction Rietveld method. A predetermined amount of an internal standard substance such as aluminum oxide or magnesium oxide is added to the pulverized sample, and after sufficient mixing in an agate mortar, powder X-ray diffraction measurement is performed. Analyze the measurement results with quantitative software to determine the vitrification rate. “SIROQUANT” manufactured by Sitronics was used as the quantitative software.

  The hydrogel composition of the present invention is prepared by containing a calcium aluminate compound in an aqueous solution (hydrogel-forming material) containing a non-ammonium type titanium peroxo compound and polyvinyl alcohol. In 100 parts of the hydrogel composition, the calcium aluminate compound is preferably 10 to 20 parts. If it is less than 10 parts, the water resistance and strength may be lowered, and if it is 20 parts or more, the strength becomes too high and the elasticity may be impaired.

  In the hydrogel composition of the present invention, those conventionally used as a crosslinking agent for a hydroxyl group or a carboxyl group can be used in combination as long as the effects of the present invention are not impaired. Conventional cross-linking agents include aliphatic aldehydes, aromatic aldehydes, compounds having a methylol group such as trimethylol melamine, boron compounds such as borax and boric acid, metal alkoxides in which Zr, Al, etc. are bonded to an organic substance. And compounds having an isocyanate group.

  Organic acids such as citric acid, acetic acid, gluconic acid, oxalic acid, formic acid, and lactic acid can also be used for the purpose of controlling the curing rate of the hydrogel composition of the present invention. Since the optimal curing rate varies depending on the construction conditions, the amount of the organic acid used is not particularly limited, but is preferably 0.25 to 2 parts, preferably 0.5 to 1 part with respect to 100 parts of the hydrogel composition. Is more preferable. If it exceeds 2 parts, an elastic body may not be obtained.

  The hydrogel composition of the present invention can be used in combination with a filler for the purpose of controlling the strength, elastic modulus and density of the cured product. The filler is not particularly limited, and an inorganic or organic filler can be used. Examples of inorganic materials include aggregates such as silica and limestone, clay minerals such as bentonite, ion exchangers such as zeolite, and organic materials include fibrous substances such as vinylon fiber, acrylic fiber, and carbon fiber, Examples thereof include ion exchange resins and water-absorbing polymers. These can be used as long as the object of the present invention is not impaired.

  As the mixing apparatus for the hydrogel composition of the present invention, any existing apparatus can be used, and examples thereof include a tilting cylinder mixer, an omni mixer, a Henschel mixer, a V-type mixer, and a Nauta mixer.

  The hydrogel composition containing the calcium aluminate compound of the present invention changes from an acidic region to an alkaline region and gels with the hydration reaction of the calcium aluminate compound. The non-ammonium type titanium peroxo compound acts as a hydration retarder for the calcium aluminate compound and can be kept below pH 8 for a while after mixing. The hydrogel composition containing a calcium aluminate compound is preferably in the acidic to neutral range, specifically about pH 5 to 8, from the viewpoints of viscosity and work safety. When the pH is 8 or more, alkaline chemical damage may occur when it adheres to the skin. If ordinary cement is used instead of the calcium aluminate compound, the pH will exceed 9 immediately after mixing.

  The ground strengthening method using the hydrogel composition of the present invention is not particularly limited because it is injected into a cavity or soil around an underground structure such as a tunnel and a sewer pipe. For example, drill a hole in a concrete wall where cavities and water leakage are seen, set an injection plug, inject the hydrogel composition of the present invention with various pumps, fill the cavity, and form a water-blocking layer on the back of the concrete To do. Moreover, it is also possible to inject using various injection pumps by inserting an injection tube from the ground around the cavity or around the structure.

  Examples will be described in detail below.

"Experiment 1"
About 0.25 g of titanium metal powder (350 mesh), 20 ml of 30% hydrogen peroxide water, 5 ml of 30% ammonia water were mixed in a beaker and dissolved while cooling in a water bath to obtain a yellow transparent titanium peroxo solution. . Next, citric acid of 1 mol or more with respect to titanium was added to the obtained solution. After the added citric acid was completely dissolved, it was dried by heating on a hot plate at 80 ° C., and the resulting compound was redissolved in distilled water to adjust the titanium concentration to 0.125 M / L. This solution was added dropwise to a high-porous cation exchange resin made Na-type with NaCl to prepare an aqueous titanium solution (A). Further, the aqueous titanium solution (a) was concentrated to prepare an aqueous titanium solution (a). Table 1 shows the properties of the aqueous titanium solution.

<Evaluation and measurement method>
Stability of the liquid: ○ when the product was stable for a long time without hydrolysis, and × when it was hydrolyzed to cause precipitation.
Appearance: Visual determination Ti concentration: Measured using an ICP emission spectroscopic analyzer (manufactured by SII Nano Technology).
Na concentration: Measured using an atomic absorption photometer (manufactured by Shimadzu Corporation).
N concentration: Measured using an organic trace element analyzer (manufactured by Yanaco Analytical Industries).
pH: Measured using a pH meter (HORIBA, F-50 series).
Compound identification: confirmed by X-ray diffraction, Raman spectroscopy, carbon 13 NMR spectroscopy.

  As shown in Table 1, non-ammonium type titanium peroxo compounds were synthesized by an ion exchange method.

"Experimental example 2"
PVA having a polymerization degree of 1700 and a saponification degree of 98.7 mol% was added to tap water and heated to 80 ° C. to prepare a PVA aqueous solution having a solid content concentration of 10%. About what mixed this PVA aqueous solution, the titanium aqueous solution (a) synthesize | combined in Experimental Example 1, and titanium aqueous solution (U), it measured Ti density | concentration and Na density | concentration similarly to Experimental Example 1, and also measured PVA density | concentration. . Moreover, the liquid state and stability (appearance) of the hydrogel-forming material were evaluated. The results are shown in Table 2.

(Materials used)
PVA: manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “K17”, polymerization degree 1700, saponification degree 98.7 mol%
Titanium aqueous solution (A): (A) in Table 1
Titanium aqueous solution (U): diisopropoxytitanium bis (triethanolaminate), manufactured by Matsumoto Pharmaceutical Co., Ltd., trade name “TC-400”, a 3-fold diluted product having a titanium concentration of 8.3%.

<Measuring method>
PVA concentration: The hydrogel-forming material was colored using iodine, and then measured by a UV-visible absorption spectrum method using a spectrophotometer (manufactured by JASCO Corporation).

  As shown in Table 2, the hydrogel-forming material of the aqueous solution of the present invention is more stable than a conventional mixture of PVA aqueous solution + titanium aqueous solution and can be stored for a long period of time (Experiment No. 2-1 The mixed aqueous solution was stable for a long time, but the mixed aqueous solution of Experiment No. 2-2 gelled after 10 minutes).

"Experiment 3"
PVA having a polymerization degree of 1700 and a saponification degree of 98.7 mol% was added to tap water and heated to 80 ° C. to prepare a PVA aqueous solution having a solid content concentration of 10%. This PVA aqueous solution was mixed with the aqueous titanium solutions (A), (I) and water synthesized in Experimental Example 1 to prepare hydrogel-forming materials having the PVA concentration, titanium concentration, and sodium concentration shown in Table 3. Table 3 shows the properties of the obtained aqueous solution. Furthermore, a calcium aluminate compound was added to each hydrogel-forming material at a ratio shown in Table 3 and mixed to obtain a hydrogel composition.
For the hydrogel-forming material, the Ti concentration, Na concentration, and PVA concentration were measured in the same manner as in Experimental Example 2. Furthermore, the elasticity, water resistance, compressive strength, and presence of ammonia odor of the hydrogel composition after gelation were measured. For comparison, the case where ordinary cement was used instead of calcium aluminate was also evaluated.

(Materials used)
Titanium aqueous solution (A): (A) in Table 1
Titanium aqueous solution (I): (I) in Table 1
Calcium aluminate compound (CA): prototype, CaO 29%, Al ₂ O ₃ 65%, SiO ₂ 3%, TiO ₂ 3%, CaO / Al ₂ O ₃ molar ratio 0.8, vitrification rate 30%, brane Specific surface area 5000 cm ² / g, density 3.05 g / cm ³
Ordinary Portland cement: Commercial products

(Measuring method)
Elasticity (restoration rate): The hydrogel composition was poured into a 5 × 5 × 5 cm mold, demolded at a material age of 1 day, unloaded after 1 cm was unloaded from the top using a commercially available pressure tester. The restoration rate was measured by measuring the height (xcm) of the specimen after unloading. The restoration rate was calculated by [1- (5-x)] × 100 (%) and used as an elasticity index.
Water resistance (mass increase): 100 g of the hydrogel composition was immersed in pure water, and the mass increase accompanying water absorption was measured after one week. It can be said that the smaller the increase in mass, the better the water resistance without the movement of moisture.
Compressive strength: The hydrogel composition was poured into a 4 × 4 × 4 cm mold, demolded at a material age of 1 day, and measured according to JIS R 5201. If the specimen did not yield even when a load was applied, the compressive strength was calculated from the load when the specimen was displaced by 50%.

  As shown in Table 3, it can be seen that the hydrogel-forming material of the present invention provides a transparent and stable aqueous solution. Moreover, it turns out that the hydrogel composition of this invention containing a calcium aluminate compound changes to an elastic body, and even if it cures in water, since the mass increase by water absorption swelling is small, it is excellent in water resistance. Furthermore, it turns out that compressive strength is high. Moreover, it has the characteristic that there is no ammonia smell.

  The aqueous gel hydrogel-forming material of the present invention is highly stable. Furthermore, by modifying the periphery of the underground structure with the hydrogel composition of the present invention, damage to the underground structure due to an earthquake can be reduced. In particular, since it is liquid before gelation and can be filled into an arbitrary shape, it has characteristics not found in elastic compositions such as rubber.

Claims (6)

A hydrogel-forming material, which is an aqueous solution containing a non-ammonium type titanium peroxo compound and polyvinyl alcohol. The hydrogel-forming material according to claim 1, wherein the non-ammonium type titanium peroxo compound is an alkali metal salt. The hydrogel-forming material according to claim 2, wherein the alkali metal concentration is 0.1 to 1.2% by mass, and the solid content concentration of polyvinyl alcohol is 4 to 10% by mass. The hydrogel-forming material according to any one of claims 1 to 3, wherein the titanium concentration is 0.4 to 1.0 mass%. The hydrogel composition which made the hydrogel formation material of any one of Claims 1-4 contain the calcium aluminate compound. A ground reinforcement method using the hydrogel composition of claim 5.