JP6366985B2 - Elastic composition and repair method using the same - Google Patents

Description

  The present invention relates to an elastic composition used mainly in the field of civil engineering and architecture.

Around underground structures such as tunnels and sewer pipes, cavities are created by the movement of groundwater. In addition to groundwater penetration into the structure, the cavity causes stress concentration due to earthquakes and natural ground pressure, and the structure is easily destroyed. It is effective to inject the filler.
Conventionally, cement-based materials and water glass-based materials have been mainly used, and the back surface of tunnels and sewage pipes is filled with a concrete pump or the like (Patent Document 1). Moreover, in order to prevent the material filled by the movement of groundwater from being washed away during the construction, development of a material imparted with quick setting has been promoted (Patent Document 2). In addition, injection of a polymer material has been studied (Patent Documents 3, 4, and 5). Studies have also been conducted on gel compositions using water-soluble polyvinyl alcohol as an elastic composition (Patent Documents 6 and 7).

JP-A-11-61123 Japanese Patent No. 3600155 JP 2002-294014 A JP 2002-371278 A JP-A-11-256138 Japanese Patent Laid-Open No. 06-207071 JP 05-117033 A

Among the fillers, cement-based materials and water-glass-based materials are not elastic, so when injected into cavities or soil existing around underground structures, cracks are likely to occur, and groundwater may enter again. Moreover, since the physical strength of the polymer material is small, it may not be sufficient for the specific stress in the underground.
On the other hand, an elastic composition using water-soluble polyvinyl alcohol can overcome the above-mentioned problems, but has a problem that the material easily foams. If bubbles are present, the volume filled with the elastic composition is reduced by the amount of foam, or voids are created locally in the elastic composition after gelation. In some cases, the compressive strength and water impermeability were lowered. There is also a construction method to increase the pump pressure in order to eliminate bubbles, but since bubbles depend on the surface tension of the liquid, it is difficult to eliminate bubbles of elastic materials such as polyvinyl alcohol, and the pump pressure is increased. In some cases, it may be necessary to select a construction tool that can withstand high pressure.

As a result of various studies on the above-described problems and requirements, the present inventor has obtained knowledge to solve the above-described problems and has completed the present invention.

That is, the present invention comprises (1) an elastic composition comprising polyvinyl alcohol, an organic titanium compound, a calcium aluminate compound, water, and an antifoaming agent, and (2) further comprising an organic acid ( 1) Elastic composition, (3) Total of polyvinyl alcohol 0.5 to 10%, organic titanium compound 1 to 10%, calcium aluminate compound 0.5 to 5%, water 75 to 95%, and organic acid The elastic composition according to (1) or (2), in which the antifoaming agent is 10 to 500 ppm in an external ratio, and (4) the antifoaming agent is a mineral oil-based material (1) to (3 The elastic construction method according to any one of (5), (1) to (4).

The elastic composition of the present invention has an appropriate gelation time, strength, elasticity, and water barrier properties, and is difficult to foam when the composition is mixed, or the foam disappears immediately even when foamed. Propose materials that are easy to do. Therefore, the durability of the structure can be improved by, for example, injecting it into cavities and voids around underground structures such as tunnels and sewer pipes.

Hereinafter, the present invention will be described in detail.
In the present invention, parts,%, and ppm are based on mass unless otherwise specified.

  The polyvinyl alcohol (hereinafter abbreviated as PVA) used in the present invention is not particularly limited, but may be modified or copolymerized with other components, and the average degree of polymerization is preferably 500 to 3000. 1000-2000 is more preferable. The saponification degree of PVA is preferably 80 mol% or more, and more preferably 90 mol% or more. When the degree of polymerization or saponification of PVA is outside the above range, it may affect the fluidity before curing, the strength after curing, the elasticity, and the water barrier property.

  The PVA used in the present invention is preferably prepared in advance as an aqueous solution. The solid content concentration is appropriately determined depending on the application, and is not particularly limited, but is usually preferably about 3 to 20%. If it is less than 3%, the elasticity of the cured product may be insufficient. If it exceeds 20%, not only will the viscosity of the aqueous solution increase, but there will also be a problem that the aqueous solution will gel under low temperature conditions.

The organic titanium compound used in the present invention is not particularly limited, but is one that reacts with a hydroxyl group or a carboxyl group (crosslinking agent). Further, it is preferable that the organic titanium compound is water-soluble, does not undergo modification due to dissociation in water, and does not lose reactivity in an aqueous solution.
In the organotitanium compound used in the present invention, the ligand is at least one selected from triethanolamine, acetylacetone, citric acid, lactic acid, malic acid, tartaric acid, and glycolic acid, and the ligand In which two or more atoms are coordinated per one atom of titanium.
Specific examples of the organic titanium compound are preferably selected from titanium lactate, diisopropoxy titanium bis (triethanolaminate), and titanium peroxocitric acid.

The calcium aluminate compound used in the present invention is a mixture of calcium raw materials such as limestone, lime and slaked lime and aluminum raw materials such as bauxite and aluminum residual ash in a predetermined ratio, baked and then pulverized. is there. 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 In the range that does not substantially impede the object of the present invention, there is no particular problem.
The molar ratio of CaO / Al ₂ O ₃ of the calcium aluminate compound is not particularly limited, but is preferably in the range of 0.8 to 2.5. If it is less than 0.8, the compressive strength of the elastic body may be lowered, and if it exceeds 2.5, the gelation time may be shortened.
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. Coarse particles of less than 1500 cm ² / g may not provide sufficient strength, and fine powders exceeding 8000 cm ² / g may be highly reactive and may not ensure sufficient pot life.
The vitrification rate of the calcium aluminate compound is not particularly limited, and it can be used regardless of whether it is crystalline or amorphous. Calcium aluminate compounds in _{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 is 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 antifoaming agent used in the present invention is a material that suppresses the generation of bubbles or immediately eliminates the generated bubbles when the materials of the elastic composition are mixed. Products generally sold as an antifoaming agent, a foam breaker, a foam suppressor, a defoaming agent, and a foaming agent can be used, and any of liquid and powder can be used.
As the antifoaming agent, mineral oil-based, polyether-based, silicone-based, etc. are known, but since the type of the antifoaming agent used in the present invention has a small effect on the gelation time, the mineral oil-based A material is preferred.

The elastic composition of the present invention can also use organic acids such as citric acid, acetic acid, gluconic acid, oxalic acid, formic acid, and lactic acid for the purpose of controlling the gelation rate. The gelation rate varies depending on the application, but it is preferably about 30 minutes to 2 hours when it is pumped over a long distance with a pump. In the present invention, citric acid is particularly preferable.

The blending ratio of PVA, organic titanium compound, calcium aluminate compound, water, and organic acid in the present invention is not particularly limited because it varies depending on the application, but PVA is 0 in 100% of the total of the above materials. 5 to 10% is preferable, and 1 to 8% is more preferable. The organic titanium compound is preferably 1 to 10%, more preferably 2 to 8%. The calcium aluminate compound is preferably 0.5 to 5%, more preferably 1 to 3%. Outside these ranges, fluidity before curing, elasticity after curing, strength, water resistance, or gelation time may be affected.
The antifoaming agent is preferably 50 to 500 ppm, more preferably 100 to 300 ppm, based on 100% of the total of PVA, organic titanium compound, calcium aluminate compound, water, and organic acid. If it is 50 ppm or less, the defoaming effect may not be excellent, and if it is 500 ppm or more, the gelation time of the elastic composition may be long.
The water is preferably 75 to 95% out of 100% in total of PVA, organic titanium compound, calcium aluminate compound, water and organic acid. If it is 75% or less, the gel time of the liquid may be too short, and if it is 95% or more, it may be too long.

In the elastic 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.
However, some conventional cross-linking agents gel immediately upon mixing with an aqueous PVA solution, gel only in an acidic atmosphere, or have a cured body with low strength. 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.

In the elastic composition of the present invention, a filler can be used in combination 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. Inorganic compounds Inorganic systems include aggregates such as silica and limestone, ion exchangers such as zeolite, and organic materials include fibrous materials such as vinylon fibers, acrylic fibers, and carbon fibers, and 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 device for the elastic composition in the present invention, any existing device can be used, and examples thereof include a tilting barrel mixer, an omni mixer, a Henschel mixer, a V-type mixer, and a Nauta mixer.

Although the construction method of filling and repairing the cavity around the underground structure using the composition of the present invention is not particularly limited, the following methods can be applied.
Drill a hole in the concrete wall where cavities and water leakage are seen, and set the injection plug. Thereafter, the composition of the present invention is injected as an injection material using various pumps to fill the cavity or form a water shielding layer on the concrete back surface. 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"
A PVA aqueous solution was prepared using PVA and water. To this PVA aqueous solution, an organic titanium compound, a calcium aluminate compound, an organic acid and an antifoaming agent were added, and mixing was immediately started. For mixing, a hand mixer having a rotation speed of 2000 rpm was used. The elastic composition was prepared by adding the material and mixing for 2 minutes. The composition of the elastic composition is shown in Table 1.
In addition, a compounding quantity is described with the addition amount (ppm) of the anti-foaming agent with respect to this total amount by making the sum total of PVA aqueous solution, an organic titanium compound, a calcium aluminate type compound, and an organic acid into 100%. The foam occupation volume ratio and gelation time of the prepared elastic composition were evaluated. The results are also shown in Table 1.

"Materials used"
PVA: manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “K-17E”, polymerization degree 1700, saponification degree 98.7 mol%
Organic titanium compound: Titanium lactate (indicated as Ti), manufactured by Matsumoto Pharmaceutical Co., Ltd., trade name “TC-310”
Calcium aluminate compound (noted as CA): prototype, CaO 50%, Al ₂ O ₃ 40%, SiO ₂ 3%, TiO ₂ 3%, CaO / Al ₂ O ₃ molar ratio 2.3, vitrification rate 98 %, Blaine specific surface area 6000 cm ² / g, density 2.92 g / cm ³
Water: tap water Organic acid: citric acid, reagent first grade antifoam A: mineral oil, manufactured by ADEKA, trade name “Adecanate B-943”
Antifoaming agent B: Mineral oil, manufactured by San Nopco, trade name “Dappo H-106”
Antifoaming agent C: polyether, manufactured by ADEKA, trade name “ADEKA NOL LG-805”
Antifoam D: Silicone, manufactured by San Nopco, trade name “Dappo H203”

"Measuring method"
Foam occupied volume ratio: The total amount of the mixed composition is immediately poured into a graduated cylinder, and a scale (h) at the lowest position at which bubbles can be seen in the composition and a scale at the highest position at which bubbles can be seen (H ) Was measured. Further evaluation was performed after 5 minutes, 10 minutes, and 30 minutes. The bubble occupation volume ratio is defined by the following formula, and the closer the numerical value is to 0, the smaller the number of bubbles.
Foam occupied volume (%) = (H−h) / H × 100
Gelation time: The mixed composition was immediately poured into a transparent styrene bottle, and the time until the liquid level, that is, the surface at the lowest position where bubbles were visible did not change even when the container was tilted was measured.

From Table 1, PVA 0.5 to 10%, organotitanium compound 1 to 10%, calcium aluminate compound 0.5 to 5%, water 75 to 95%, organic acid, 100% total of the materials described above On the other hand, the elastic composition containing 50 to 500 ppm of the antifoaming agent in the outer split has a small bubble occupation volume ratio and can exhibit an appropriate gelation time. Further, the mineral oil-based antifoaming agent has less influence on the gelation time than other antifoaming agents.

"Experimental example 2"
In the same manner as in Experimental Example 1, PVA, an organic titanium compound, a calcium aluminate compound, an organic acid, water, and an antifoaming agent A were mixed to prepare an elastic composition having nine types of blending. The prepared elastic composition was poured into a mold or a simulated specimen after a certain time from mixing, and the compressive strength, elastic modulus, and water impermeability were evaluated. The results are also shown in Table 2. Table 2 also shows the bubble occupation volume ratio after each elapsed time measured in Experimental Example 1.

"Materials used"
Elastic composition a: PVA 3%, organic titanium compound 5%, calcium aluminate compound 2%, water 90%, antifoam A and organic acid are not added elastic composition b: PVA 3%, organic titanium compound 5%, Calcium aluminate compound 2%, water 90%, no organic acid added, antifoam A 200 ppm
Elastic composition c: PVA 3%, organic titanium compound 5%, calcium aluminate compound 2%, water 88%, organic acid 2%, antifoam A 200 ppm
Elastic composition d: PVA 12%, organic titanium compound 5%, calcium aluminate compound 2%, water 79%, organic acid 2%, antifoam A 200 ppm
Elastic composition e: PVA 3%, organic titanium compound 12%, calcium aluminate compound 2%, water 81%, organic acid 2%, antifoaming agent A 200 ppm
Elastic composition f: PVA 3%, organic titanium compound 5%, calcium aluminate compound 7%, water 83%, organic acid 2% defoamer A 200 ppm
Elastic composition g: PVA 2%, organic titanium compound 2%, calcium aluminate compound 1%, water 95%, no organic acid added, antifoam A 200 ppm
Elastic composition h: PVA 1%, organic titanium compound 1%, calcium aluminate compound 1%, water 97%, no organic acid added, antifoam A 200 ppm
Elastic composition i: PVA 3%, organic titanium compound 5%, calcium aluminate compound 2%, water 88%, organic acid 2%, antifoam A 30 ppm

"Measuring method"
Compressive strength: The mixed elastic 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. When the specimen did not yield even when loaded, the compressive strength was calculated from the load when the specimen was displaced by 50%.
Elastic modulus: The mixed elastic composition was poured into a 3 × 3 × 3 cm mold and cured in an environment of 20 ° C. for 7 days to prepare a specimen. For the measurement, a commercially available universal testing machine (autograph) was used to measure the relationship between pressure and strain when loaded on the specimen, and the elastic modulus was calculated from the stress and displacement when displaced by 5 mm.
Water impermeability: The mixed elastic composition was injected into the simulated specimen, the weight of the simulated specimen was measured 24 hours after the injection, and the amount of water leakage was calculated to evaluate the water impermeability. In the simulated test specimen, a hole having a diameter of 2 mm was formed in the lower part of the side surface of a 3 L rectangular parallelepiped polypropylene container, filled with 2.7 kg of river sand, and 600 ml of tap water was added from the upper part to cause water leakage. Immediately thereafter, a total of 10 ml of the elastic composition was injected from the hole of the mock test specimen at a rate of 1 ml per second using a syringe with a capacity of 10 ml.

Table 2 shows that PVA 0.5 to 10%, organic titanium compound 1 to 10%, calcium aluminate compound 0.5 to 5%, water 75 to 95%, and total 100% of organic acid are removed on an extra basis. The elastic composition containing 50 to 500 ppm of the foaming agent is rich in elasticity while having an appropriate compressive strength and has a water shielding property. This is thought to be due to the two factors that the blending is appropriate and that the foam occupied volume ratio is small and the elastic composition is sufficiently filled.

  Due to the elastic composition of the present invention and the repair method using the same, it has a high defoaming effect compared to conventional filling materials and can have an appropriate gelation time, strength, elasticity, and water barrier, It can be used widely in the field of architecture.

Claims (4)

Mineral oil-based material for 100% total of polyvinyl alcohol 0.5-10% , organic titanium compound 1-12% , calcium aluminate compound 0.5-7% and water 75-95% An elastic composition comprising 50 to 700 ppm of an antifoaming agent. The elastic composition according to claim 1, further comprising an organic acid. For polyvinyl alcohol 0.5-10%, organotitanium compound 1-10%, calcium aluminate compound 0.5-5%, water 75-95%, and when present, a total of 100% of organic acids, The elastic composition according to claim 1 or 2 , wherein the antifoaming agent which is a mineral oil based material is 50 to 500 ppm. The repair method characterized by using the elastic composition of any one of Claims 1-3 .