JP7131915B2 - Concrete structure repair method - Google Patents

Description

The present disclosure relates to a method for repairing concrete structures.

Concrete structures have the advantages of high strength, excellent workability, and low cost. Concrete structures have excellent durability, but after long-term use, carbon dioxide in the atmosphere permeates together with moisture, causing neutralization, and chloride ions contained in sea breezes and antifreeze sprays permeate. As a result, it may corrode and expand, resulting in cracks.
As an attempt to prevent such spalling of concrete, Patent Literatures 1 and 2, etc. propose to use various spalling-preventing laminated substrates in which a mesh sheet and a non-woven fabric are combined.

JP 2012-26238 A JP 2013-019146 A

Repair materials used for repairing concrete structures are required to have higher strength in order to reliably prevent the spalling of concrete. At the same time, there is a strong demand for a method of repairing concrete structures that allows simple and easy repair and allows the performance of the original repair material to be fully demonstrated.
The present disclosure has been made in view of the above problems, and the repair material used for repairing concrete structures has higher strength, and the repair of concrete structures can be performed simply and easily. The purpose is to provide a method.

The present application includes the following inventions.
(1) A repair method using a repair material used for repairing existing concrete structures,
A curable liquid composition comprising a composition containing an aqueous solution of sodium silicate, potassium silicate, lithium silicate or a mixture thereof and a curing agent, and a repair base material having at least two layers of sheet members laminated are prepared respectively. process and
a step of impregnating the repair base material with the curable liquid composition and attaching it to a concrete structure;
a step of applying an aqueous solution containing divalent or higher cations to the base material for repair impregnated with the curable liquid composition and attached to the concrete structure. Method.
(2) A composition containing as a main component at least one selected from the group consisting of dialdehydes, inorganic acid esters, organic acid metal salts, inorganic acid metal salts, metal oxides and metal hydroxides. A method for repairing a concrete structure as described above, comprising:
(3) The method for repairing a concrete structure described above, wherein the metal oxide is metakaolin.
(4) The method for repairing a concrete structure described above, wherein the metal oxide comprises a pozzolanic active material having an electrical conductivity difference of 0.4 mS/cm or more.
(5) The method for repairing a concrete structure, wherein the curable liquid composition exhibits a viscosity of 400 to 3000 mPa·s at 25°C.
(6) The above-described concrete structure repair method, wherein the aqueous solution containing divalent or higher cations is an aqueous solution of magnesium sulfate or aluminum sulfate.
(7) The aqueous solution containing divalent or higher cations is 40% of sodium silicate, potassium silicate, lithium silicate, or a mixture thereof contained in the curable liquid composition impregnated into the repair base material. The method for repairing concrete structures described above, wherein the solid content is 0.5 to 4 parts by weight with respect to 100 parts by weight of the aqueous solution converted to weight percent.
(8) The method for repairing a concrete structure described above, wherein the aqueous solution containing divalent or higher cations has a concentration of 5 to 30% by weight.
(9) When the sheet-like member has a first layer and a second layer from the concrete structure side, the first layer is a multifilament having a tensile strength of 150 N or more and is formed into a multiaxial mesh with an opening of 5 to 25 mm. The method for repairing a concrete structure as described above, wherein the sheet-like members are combined, and the second layer is a liquid-permeable sheet-like member having a tear strength of 2.0 N or more.

The base material for repairing concrete structures of the present invention can use an inorganic curable liquid composition, which minimizes or does not impair the deterioration of the inherent fire resistance performance of concrete structures and ensures adhesive strength. Therefore, the reinforcement strength can be improved.
In addition, in the concrete structure repair method of the present invention, the concrete structure can be repaired easily and reliably using the repair base material described above.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view showing an example of a concrete structure repair form using the concrete structure repair material (two-layer structure) of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view showing an example of a concrete structure repair form using the concrete structure repair material (three-layer structure) of the present invention.

The concrete structure repair method of the present invention is a repair method using a repair material used for repairing an existing concrete structure, and is mainly composed of
A curable liquid composition comprising a composition containing an aqueous solution of sodium silicate, potassium silicate, lithium silicate or a mixture thereof and a curing agent; a base material for repair in which at least two layers of sheet members are laminated; respectively preparing an aqueous solution containing cations of
a step of impregnating the repair base material with the curable liquid composition and attaching it to a concrete structure;
and coating the repair base material impregnated with the curable liquid composition and attached to the concrete structure with the aqueous solution containing the divalent or higher cation.
According to such a repair method, there is no need to repeat painting and drying as in the conventional method, and the work can be performed simply and efficiently, and workability is also excellent.

[Preparation of curable liquid composition, base material for repair, and aqueous solution containing divalent or higher cations]
The repair material in the present application is used for repairing existing concrete structures, and includes a repair base material obtained by laminating at least two layers of sheet-like members, and a curable liquid composition impregnated into the repair base material. and an aqueous solution containing divalent or more valent cations to be applied to the repair base material impregnated with the curable liquid composition. The curable liquid composition and the repair base material may exist separately, but the repair base material is impregnated with the curable liquid composition as will be described later.
As shown in FIGS. 1 and 2, the repair materials 5 and 15 are applied, for example, to the concrete structure 1 so that the surface of the concrete structure 1 is coated and impregnated with the curable liquid composition of the repair materials. The composition cures or bonds with the concrete structure to repair the concrete structure 1 .

(Repair base material)
The base material for repair is configured by laminating at least two layers of sheet-like members. For example, as shown in FIG. 1, the repair material 5 is used by laminating the first layer 2 and the second layer 3 in this order from the concrete structure 1 side. Moreover, as shown in FIG. 2, the repair material 15 may have a configuration in which a third layer 4, a first layer 2 and a second layer 3 are laminated in this order from the concrete structure 1 side.
In particular, the first layer is preferably a sheet-like member in which multifilaments are combined in a multiaxial mesh.
Furthermore, the second layer is preferably a liquid-permeable sheet-like member having a tear strength of 2.0 N or more.

(first layer)
The first layer 2 is preferably a sheet member in which multifilaments are combined in a multiaxial mesh. The multifilament is preferably constructed using long fibers, and preferably has a tensile strength of 150 N or more. The value X represented by the formula (1) of the sheet-like member in which multifilaments are combined in a multiaxial mesh shape is preferably 2.0 or more, and is preferably 2.5 or more, 2.8 or more, or 3.0 or more. It is more preferable to have
X=A×B (1)
Here, A represents the tensile strength kN/50 mm in one direction of the sheet-like member, and B represents the number of axes of the sheet-like member. A can take any value by changing the number of multifilaments per 50 mm. Examples of B include those having a range of 2 to 4. Among them, A is preferably 0.75 kN or more, and B is preferably 2 to 3.
With this configuration, the first layer 2 can fulfill the function of a load-bearing layer that receives concrete pieces falling from a concrete structure.

Materials for the first layer 2 include polyester, polyolefin, vinylon, aramid, carbon fiber, and glass fiber. Among them, it is preferable to use a vinylon mesh sheet or a glass mesh sheet. Glass yarn or roving is preferably used as the glass fiber. A glass yarn is a plied yarn obtained by twisting glass fibers, and a roving is a bundle of glass fibers. Weaving methods of the multiaxial mesh include plain weave, twill weave, leno weave, and braided cloth. The direction of weaving of the multiaxial mesh may be biaxial or more multiaxial woven fabric.

The thickness of the first layer 2 is preferably 0.1 mm or more and 1.5 mm or less, more preferably 0.3 mm or more and 1 mm or less.
The first layer preferably has a basis weight of 50 g/mm ² or more, more preferably 60 g/mm ² or more, still more preferably 75 g/mm ² or more.
By setting the basis weight within such a range, it is possible to improve the tensile strength and ensure the sufficient yield strength of the repair material 5 without causing breakage when the concrete piece is spalled.

The first layer is preferably a biaxial woven fabric having an opening of 5 mm or more and 25 mm or less, more preferably a biaxial woven fabric having an opening of 5 mm or more and 25 mm or less and a basis weight of 50 g/mm ² or more. Alternatively, it may be a multiaxial woven fabric having an aperture ratio equivalent to that of the biaxial woven fabric.
In particular, the first layer is more preferably a biaxial or triaxial mesh sheet member in which multifilaments having a tensile strength of 150 N or more are combined with an opening of 5 to 25 mm.
By setting the mesh opening within this range, the adhesive strength between the second layer and the concrete structure or between the second layer and the third layer can be improved, and sufficient strength of the repair material 5 can be ensured. In addition, the number of long fibers per unit area of the first layer is set to an appropriate number to increase the resistance when the first layer breaks out of the second layer, and to ensure sufficient strength of the repair material 5. can.

(Second layer)
The second layer 3 is preferably a liquid-permeable sheet-like member. The liquid-permeable sheet-like member preferably has a tear strength of 2.0 N or more. By setting the tear strength to 2.0 N or more, the second layer 3 can fulfill the function as a reinforcing layer that increases resistance when the first layer breaks out of the second layer.

The shape of the second layer 3 includes woven fabric, non-woven fabric, and the like. Materials include polyester, polyolefin, vinylon, aramid, carbon fiber, and glass fiber. Among them, polypropylene nonwoven fabric or glass nonwoven fabric is preferable, and long-fiber nonwoven fabric is more preferable. Since the glass nonwoven fabric has excellent compatibility with the curable liquid composition, the curable liquid composition easily permeates, and when the curable liquid composition is cured, the repair material is firmly fixed to the concrete structure. can be done. Suitable glass nonwoven fabrics include chopped strand mats, glass paper, felt, and the like.
When a polypropylene nonwoven fabric is used, the fibers may be subjected to hydrophilization treatment in order to increase compatibility with the curable liquid composition.

The thickness of the second layer 3 is preferably 0.1 mm or more and 1.0 mm or less, more preferably 0.15 mm or more and 0.5 mm or less.
By setting the thickness in such a range, the first layer satisfies the function as a reinforcing layer that enhances the resistance when breaking through the second layer, and the amount of impregnation of the curable liquid composition into the substrate. can be suppressed, which is economically advantageous.

(Lamination integration)
The base material for repair, which is formed by laminating at least two layers of sheet-like members, may be integrated by impregnating them with the curable liquid composition, but it is preferable to integrate them in advance. By integrating the sheet members, it is possible to prevent the sheet members from being displaced during the coating and impregnation.
The integration method can utilize mechanical fiber entanglement, chemical adhesion, etc. Examples include fulling, needle punch, chemical bond, thermal bond, hydroentanglement, and the like.

FIG. 1 shows a case where the repair base material has a two-layer structure, and FIG. 2 shows a case where the repair base material has a three-layer structure, but the repair base material may have four or more layers. Even in the case of four or more layers, the second layer 3 is preferably arranged outside the first layer 2 when counted from the side in contact with the concrete structure. With such a laminated structure, both the strength of the repair materials 5 and 15 and the adhesion to the concrete structure 1 can be achieved. In addition, the maximum number of laminations of the base material for repair is not particularly limited.

(Curable liquid composition)
The curable liquid composition is applied to and/or impregnated on a repair substrate. By coating and/or impregnating a repair base material with the curable liquid composition and then curing the curable liquid composition, the concrete structure and the repair material can be bonded. For example, the curable liquid composition may be liquid. By adhering the repair material, it is possible to prevent concrete pieces from falling off from the deteriorated portion of the concrete structure.

The curable liquid composition is preferably a composition containing an aqueous solution of sodium silicate, potassium silicate, lithium silicate or a mixture thereof (silicate aqueous solution) and a curing agent. The silicate aqueous solution can be used after adjusting the pH with an alkali metal hydroxide aqueous solution such as sodium hydroxide and potassium hydroxide. A silicate aqueous solution obtained by adjusting the pH of an alkali metal hydroxide aqueous solution is also a silicate aqueous solution.

In addition, sodium silicate and potassium silicate can form calcium hydroxide and C—S—H gel in the concrete when applied and/or impregnated on the surface of the concrete structure 1, and thus can be used as a repair material. The adhesive strength of the concrete structure can be made stronger.
Such a curable liquid composition preferably has a viscosity of 400 to 3000 mPa·s at 25°C. By setting it as such a viscosity, the impregnating property to the base material for repair can be ensured. In addition, dripping of the curable liquid composition when adhered to a concrete structure can be prevented.

Curing agents are ingredients for accelerating the curing of sodium silicate, potassium silicate, lithium silicate, or mixtures thereof. The curing agent includes those adjusted to near neutral pH in order to promote the dehydration condensation reaction. Also, alkali metals in sodium silicate, potassium silicate, lithium silicate, or mixtures thereof may be replaced with divalent or higher metals to form Si--O--metal--O--Si bonds to promote curing. There are things you can do. The curing agent preferably contains one or more selected from the group consisting of organic acid esters, dialdehydes, inorganic acid esters, organic acid metal salts, inorganic acid metal salts, metal oxides and metal hydroxides. More preferably, one or more compounds selected from the group consisting of organic acid esters, metal oxides and metal hydroxides are used.

Organic acid esters have the advantage of being able to promote the formation of Si—O bonds by generating acid in an aqueous solution. Examples of organic acid esters include carbonate esters and acetate esters. Among them, triacetin is preferred.
Examples of dialdehydes include malondialdehyde and the like.
Examples of inorganic acid esters include esters of nitric acid, hydrochloric acid, sulfuric acid and phosphoric acid, such as trimethyl phosphate.
Examples of organic acid metal salts include alkali metal salts such as formic acid, acetic acid, malonic acid and carbonic acid, and alkaline earth metal salts such as sodium hydrogen carbonate.
Examples of inorganic acid metal salts include alkali metal salts such as nitric acid, hydrochloric acid, sulfuric acid and phosphoric acid, and alkaline earth metal salts such as magnesium sulfate, magnesium carbonate and calcium carbonate.

Metal oxides and metal hydroxides form Si—O—metal—O—Si bonds by dissolving metal ions, and can harden sodium silicate, potassium silicate, lithium silicate, or mixtures thereof. . Metal oxides and metal hydroxides include magnesium oxide, calcium oxide, zinc oxide, magnesium hydroxide, calcium hydroxide, and pozzolanic active substances.
The metal oxide is preferably a pozzolanic active substance (hereinafter, a curable liquid composition whose curing agent is a pozzolanic active substance may be referred to as a “geopolymer”). A pozzolanic active substance is a substance that does not itself react with water, but reacts with a mixture of water and calcium oxide or calcium hydroxide to harden. Examples include silica dust, diatomaceous earth, talc, aerosil, White carbon, kaolin, metakaolin, activated clay, acid clay and the like can be mentioned, and among them, metakaolin is preferred.
The pozzolanic active substance preferably has an electrical conductivity difference of 0.4 mS/cm or more, more preferably 0.5 mS/cm or more, 0.6 mS/cm or more, or 0.7 mS/cm or more. More preferably, it is 8 mS/cm or more, 1.0 mS/cm or more, or 1.2 mS/cm or more. Such a difference in electrical conductivity ensures sufficient reactivity with the aqueous silicate solution, and increases the bonding strength between the repair material 5 and the concrete structure 1 . The electrical conductivity difference here is an index related to the reactivity of the pozzolanic active substance induced by an alkaline substance, and the electrical conductivity of the saturated calcium hydroxide aqueous solution before and after adding the pozzolanic active substance obtained by the evaluation method described later. means the difference between
The pozzolanic active substance has a silica component content of 40% by weight or more when the silica component in the pozzolanic active substance is converted to _SiO2 , or an alumina component content of ₃₀ % by weight when the alumina component is converted to _Al2O3 . % or more is preferable.
The pozzolanic active substance is usually in the form of lumps or powder, but the lump or powder may be used as it is. Moreover, in order to activate it, the state thereof may be changed by using a method such as thermal spraying, pulverization and classification, or the action of mechanical energy.

As a thermal spraying method, a thermal spraying technique applied to ceramic coatings is applied. Thermal spraying techniques include, for example, plasma thermal spraying, high-energy gas thermal spraying, arc thermal spraying, and the like. Preferably, the material powder is melted at a temperature of 2000-16000° C. and sprayed at a speed of 30-800 m/sec to obtain a powder having a specific surface area of 0.1-100 m ² /g.
Any known method can be employed as a method for pulverization and classification. Pulverization includes a method using a jet mill, roll mill, ball mill, or the like. Classification includes methods using sieving, specific gravity, wind force, wet sedimentation, and the like. These means can be optionally used in combination.
Examples of the method of applying mechanical energy include a method using a ball medium mill, a medium agitating mill, a roller mill, and the like. The mechanical energy to act is preferably 0.5 to 30 kwh/kg in order to minimize the load while appropriately activating.

The blending amount of the curing agent varies depending on the rate of elution into sodium silicate, potassium silicate, lithium silicate, or a mixture thereof, and is blended in the range of 0.2 to 150 parts by weight per 100 parts by weight of the entire composition. preferably. By setting this range, it is possible to sufficiently contribute to the acceleration of curing of sodium silicate, potassium silicate, lithium silicate, or mixtures thereof. Also, even when a liquid organic substance is used as a curing agent, it is possible to maintain the curing agent component incorporated into the Si—O bonds and lead to sufficient curing. Furthermore, even when a powdery inorganic substance is used as a curing agent, the repair base material can be sufficiently impregnated with the composition without excessively increasing the viscosity of the composition. From another point of view, the curing agent is contained in an amount equivalent to 0.1 to 100 parts by weight with respect to 100 parts by weight of a 40% by weight aqueous solution of sodium silicate, potassium silicate, lithium silicate or a mixture thereof. However, it is preferably contained in an amount equivalent to 1 to 80 parts by weight, more preferably in an amount equivalent to 1 to 60 parts by weight.
In particular, when the curing agent here contains a strong acid salt containing a divalent or higher cation as an inorganic acid metal salt, the viscosity during construction (that is, workability) is taken into consideration within the range described above. , it is preferable to select an amount that can ensure the pot life, that is, a small amount (an amount near the lower limit).

The total content of sodium, potassium, lithium or a mixture thereof derived from the silicate aqueous solution in the geopolymer is M ₂ O (M is sodium , potassium and lithium) is preferably 5 to 30% by weight, more preferably 10 to 30% by weight. Also, the content of aluminum derived from the pozzolanic active substance is preferably 20 to 40% by weight, preferably 25 to 35% by weight, in terms of Al ₂ O ₃ with respect to the dry solid content of the cured product. is more preferable.

Furthermore, the curable liquid composition is preferably an aqueous solution of sodium silicate, potassium silicate, lithium silicate, or a mixture thereof and has a numerical value n represented by the following formula of 0.4 to 1.1, preferably 0.5 to 1.1 is more preferred, and 0.5 to 1.0 is even more preferred.
n=S/M
(S: the number of moles of silicon contained in the aqueous solution, M: the number of moles of alkali metal contained in the aqueous solution).

(other ingredients)
The curable liquid composition may contain additives known in the art in addition to the above components. Examples include fillers, dispersants, curing time modifiers, pigments, antioxidants, polymer emulsions, and the like. These are not particularly limited, and known ones can be used. The filler may be any of those commonly used as fillers. Examples thereof include carbon, cellulose, mineral fine powder, and synthesized inorganic crystal powder. Polymer emulsions include acrylic rubber, styrene-butadiene rubber, mixtures thereof, and the like. These additives can be used in any amount as long as they do not impair the intended effects of the curable liquid composition. In particular, the polymer emulsion is preferably blended so that the solid weight of the polymer is 3 to 10% by weight with respect to the total dry solid weight of the curable liquid composition. Thereby, the fluidity of the curable liquid composition can be improved, the adhesive strength of the cured product can be improved, and the drying shrinkage of the cured product can be suppressed.

The amount of the curable liquid composition impregnated into the repair base material is not particularly limited. It is preferable to adjust so that the whole base material can be firmly integrated. For example, the weight ratio of the base material for repair to the curable liquid composition is preferably about 1:4 to 1:12, more preferably 1:4 to 1:10.

(Aqueous solution containing divalent or higher cations)
The aqueous solution containing divalent or higher cations may have any pH as long as it contains divalent or higher cations. Among them, a strong acid salt is preferable. Examples of divalent or higher cations include magnesium and aluminum. Examples of strong acid salts include salts of hydrochloric acid, sulfuric acid, nitric acid and the like. Among them, magnesium sulfate or aluminum sulfate is preferable.
The concentration of the aqueous solution containing divalent or higher cations is preferably 2 to 50% by weight, more preferably 5 to 30% by weight. If the concentration is too low, the amount of coating will increase, resulting in poor workability. If the concentration is too high, uniform coating will become difficult, resulting in poor workability. In particular, the aqueous solution containing divalent or higher cations preferably has a concentration of 5 to 30% by weight.

[Impregnation and application of curable liquid composition]
(Coating and impregnation step)
A curable liquid composition is applied and/or impregnated onto a repair substrate. The repair base material may be formed and then impregnated with the curable liquid composition, the repair base material may be formed after impregnation with the curable liquid composition, or the repair base material may be formed. It may be impregnated with the curable liquid composition. In addition, the curable liquid composition may be impregnated either before or after attaching the base material for repair to the target concrete structure.

Methods for impregnating the curable liquid composition include, for example, (1) a hand lay-up method in which a roller is used to manually apply and impregnate, (2) a method of applying and impregnating by spraying, and (3) repair using a mold. (4) After defining the thickness of the repair substrate by reducing the pressure, the curable liquid composition is injected under reduced pressure. A method of impregnating a repair base material with the composition, (5) immersing the repair base material in the curable liquid composition, continuously impregnating the repair base material with the curable liquid composition, and then using a roll (6) a method of continuously applying and impregnating by roll transfer; These may be used in combination.
In order to improve workability during impregnation, and to prevent dust from adhering to the impregnated sheet and to prevent the impregnated sheets from adhering to each other, the front and back surfaces of the repair base material may be covered with a resin protective film. This protective film is removed when affixing to the concrete structure.

(Affixing process)
A base material for repair impregnated with a curable liquid composition is attached to a concrete structure. At this time, it is important to remove air bubbles that have entered between the repair base material impregnated with the curable liquid composition and the surface of the concrete structure in order to increase the adhesion to the surface of the concrete structure. As a method for removing air bubbles, a method of expelling air bubbles to the outside using a roll or a metal spatula is suitable.
The coating and impregnation step and the sticking step may be performed independently or simultaneously.

(Curing process)
Curing of the curable liquid composition impregnated in the base material for repair is performed by placing the base material in close contact with the concrete structure. The curing time of the curable liquid composition is preferably 15 to 300 minutes, more preferably 30 to 240 minutes, from the viewpoint of securing the time for the surface of the concrete structure to be impregnated with the curable liquid composition. be. The curing time depends on the content of sodium, potassium, lithium or a mixture thereof derived from the aqueous silicate solution and the ratio of SiO ₂ and M ₂ O (M is sodium, potassium and lithium) derived from the aqueous silicate solution (SiO ₂ / M ₂ O), the amount of water contained, the amount of curing agent, and the electrical conductivity difference of the pozzolanic active material, the content of aluminum, and the like.
After curing of the curable liquid composition is completed, the repair base material impregnated with the curable liquid composition can be adhered to the concrete structure.

[Aqueous solution coating]
An aqueous solution containing cations having a valence of 2 or more is applied to a concrete structure in which a base material for repair impregnated with a curable liquid composition is placed in close contact with the concrete structure. From the viewpoint of assisting the curing of the curable liquid composition, it is preferable that the application of the aqueous solution containing divalent or higher cations is started within 7 days from immediately after the application of the curable liquid composition. , more preferably after 30 minutes to 24 hours. By setting the concentration within this range, evaporation of water contained in the curable liquid composition proceeds sufficiently, and an aqueous solution containing divalent or higher valent cations can sufficiently permeate.
A general method can be used for the coating method, and examples thereof include a brush, a roller, and a spray gun.
When the application of the aqueous solution containing divalent or higher cations is completed, the cured state of the curable liquid composition can be made stronger, and the repair of the concrete structure can be completed.

The application of the aqueous solution containing divalent or higher cations to the repair base material impregnated with the curable liquid composition is performed for the purpose of assisting the curing of the curable liquid composition. Preferably, the composition is applied uniformly over the entire impregnated repair substrate.
The aqueous solution containing divalent or higher cations is solid content with respect to 100 parts by weight of sodium silicate, potassium silicate, lithium silicate or a mixture thereof contained in the impregnated curable liquid composition, converted to 40% by weight. is preferably 0.5 to 10 parts by weight, more preferably 0.5 to 4 parts by weight. By setting the content within this range, it is possible to obtain the effect of sufficiently assisting curing, avoid deposition of coating components on the surface, and improve the appearance.
Hereinafter, the concrete structure repair method of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these.

Example A-1
A silicate aqueous solution (SiO ₂ =16.3%, Na ₂ O = 10.5%) prepared by adding 62 g of a 27 wt% sodium hydroxide aqueous solution to 46 g of a No. 3 sodium silicate aqueous solution specified in JIS K 1408, and other 11 g of a styrene-butadiene rubber emulsion (trade name: LX407 F43, manufactured by Nippon Zeon Co., Ltd.) was added as a component polymer emulsion and stirred for 24 hours to obtain an aqueous silicate solution containing other components.
A curable liquid composition was prepared by mixing 59 g of metakaolin (manufactured by BASF, trade name: SP-33, electrical conductivity difference of 0.8 mS/cm) as a curing agent into the above aqueous solution.
Also, a biaxial mesh sheet made of vinylon multifilament with a tensile strength of 250 N (weight per unit area: 90 g/m ² , opening: 7 mm, thickness: 0.35 mm, X=2.5) was added to a glass nonwoven fabric (weight per unit area: 25 g/m ² , 0.2 mm thickness, tensile strength 45 N/25 mm.
A repair base material impregnated with the curable liquid composition was produced by impregnating 170 g of the curable liquid composition into the prepared repair base material of 400 mm×400 mm.
10% by weight aqueous solution of magnesium sulfate as an aqueous solution containing divalent or higher cations after 3 hours from attaching the base material for repair impregnated with the curable liquid composition to a test piece of concrete structure13. 4 g (1.9 parts by weight as solid content with respect to 100 parts by weight of silicate aqueous solution converted to 40% by mass) was applied and cured for 3 days under standard conditions (temperature 23 ° C., relative humidity 50%), An evaluation sample was obtained.

Example A-2
Except that 10.05 g of a 20% by weight aluminum sulfate aqueous solution (2.9 parts by weight as a solid content with respect to 100 parts by weight of a 40% converted silicate aqueous solution) was used as the aqueous solution containing divalent or higher cations. An evaluation sample was obtained in the same manner as in Example A-1.

Example A-3
Except for using 44.7 g of a 3% by weight magnesium sulfate aqueous solution (1.9 parts by weight as a solid content with respect to 100 parts by weight of a 40% converted silicate aqueous solution) as an aqueous solution containing divalent or higher cations. An evaluation sample was obtained in the same manner as in Example A-1.

Comparative Example A-1
An evaluation sample was obtained in the same manner as in Example A-1, except that the aqueous solution containing a divalent or higher cation was not applied.

Comparative Example A-2
Except that 13.4 g of a 10% by weight sodium sulfate aqueous solution (1.9 parts by weight as a solid content with respect to 100 parts by weight of a 40% converted silicate aqueous solution) was used as the aqueous solution containing divalent or higher cations. An evaluation sample was obtained in the same manner as in Example A-1.

(Electrical conductivity difference)
According to "Cement Concrete Research, Vol.19, pp.63-68, 1989" for pozzolanic active substances, the electrical conductivity of 200 ml of a Ca(OH) ₂ saturated aqueous solution is measured at 40±1°C. Subsequently, 5 g of metakaolin was added, and after 2 minutes of stirring, the electrical conductivity was measured.

(push-out strength)
The spalling prevention performance of the concrete structure repair materials of each example and comparative example was evaluated by a push-out test described in "Bridge Structure Design Guidelines Concrete Fragmentation Prevention Edition" published by Metropolitan Expressway Company Limited. Specifically, the repair material prepared in each example and comparative example was attached to a test body and cured at a temperature of 23°C and a relative humidity of 50°C for 3 days. After that, the maximum load at a displacement of 10 to 50 mm was measured by performing a push-out test on the repair material attached to the specimen.

Example B-1
As a curable liquid composition, 150 g of a sodium silicate No. 3 aqueous solution defined in JIS K 1408, 22.5 g of calcium carbonate porous particles (manufactured by Shiraishi Calcium Co., Ltd., trade name: Brilliant-15) as a curing agent, and 7.5 g of triacetin. (manufactured by Tokyo Kasei Kogyo Co., Ltd.) and 0.4 g of a nonionic surfactant (polyoxyethylene (5) lauryl ether) as a dispersing agent for other components, to prepare a curable liquid composition.
An evaluation sample was obtained in the same manner as in Example A-1, except that the obtained curable liquid composition was used. That is, in this embodiment, as the aqueous solution containing divalent or higher cations, 13.4 g of 10% by weight magnesium sulfate aqueous solution (1.0% solid content per 100 parts by weight of silicate aqueous solution converted to 40% by weight) parts by weight) and aged for 3 days under standard conditions (temperature of 23° C., relative humidity of 50%) to obtain an evaluation sample.

Example B-2
Except for using 17.9 g of a 20% by weight aluminum sulfate aqueous solution (2.6 parts by weight as a solid content with respect to 100 parts by weight of a 40% converted silicate aqueous solution) as an aqueous solution containing divalent or higher cations. An evaluation sample was obtained in the same manner as in Example B-1.

Comparative Example B-1
An evaluation sample was obtained in the same manner as in Example B-1 except that the aqueous solution containing cations having a valence of 2 or higher was not applied.

<Performance evaluation>
The punch strength was measured in the same manner as described above for the repair materials attached to the test pieces of the above Examples and Comparative Examples. Table 2 shows the results.

1 concrete structure 2 first layer 3 second layer 4 third layer 5, 15 repair material

Claims (8)

A repair method performed at room temperature using a repair material used for repairing existing concrete structures,
A curable liquid composition comprising a composition containing an aqueous solution of sodium silicate, potassium silicate, lithium silicate or a mixture thereof and a curing agent; a base material for repair in which at least two layers of sheet members are laminated; respectively preparing an aqueous solution containing cations of
a step of impregnating the repair base material with the curable liquid composition and attaching it to a concrete structure;
a step of applying an aqueous solution containing the divalent or higher cations to the repair base material impregnated with the curable liquid composition and attached to the concrete structure ;
A method for repairing a concrete structure , wherein the curable liquid composition exhibits a viscosity of 400 to 3000 mPa·s at 25°C . A composition in which the curing agent contains at least one selected from the group consisting of dialdehydes, organic acid esters, inorganic acid esters, organic acid metal salts, inorganic acid metal salts, metal oxides and metal hydroxides as a main component. The method for repairing a concrete structure according to claim 1, wherein the concrete structure is composed of a material. 3. The method of repairing a concrete structure according to claim 2, wherein said metal oxide is metakaolin. 4. The method for repairing a concrete structure according to claim 2 or 3, wherein said metal oxide comprises a pozzolanic active material having an electrical conductivity difference of 0.4 mS/cm or more. The method for repairing a concrete structure according to any one of claims 1 to 4 , wherein the aqueous solution containing divalent or higher cations is an aqueous solution of magnesium sulfate or aluminum sulfate. The aqueous solution containing cations with a valence of 2 or more has a coating amount equivalent to 40% by weight of sodium silicate, potassium silicate, lithium silicate, or a mixture thereof contained in the curable liquid composition impregnated into the repair base material. The method for repairing a concrete structure according to any one of claims 1 to 5 , wherein the solid content is 0.5 to 4 parts by weight with respect to 100 parts by weight of the aqueous solution of. The method for repairing a concrete structure according to any one of claims 1 to 6 , wherein the aqueous solution containing divalent or higher cations has a concentration of 5 to 30% by weight. In the sheet-shaped member, when the first layer and the second layer are formed from the concrete structure side, the first layer is a sheet in which multifilaments having a tensile strength of 150 N or more are combined in a multiaxial mesh shape with an opening of 5 to 25 mm. The method for repairing a concrete structure according to any one of claims 1 to 7 , wherein the second layer is a liquid-permeable sheet-like member having a tear strength of 2.0 N or more.

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