JP7733432B2 - Repair materials and repair methods for concrete structures - Google Patents

Description

This disclosure relates to repair components and repair methods for concrete structures.

Concrete structures have the advantages of being high strength, easy to construct, durable, and inexpensive, so many concrete structures were built in Japan, especially during the period of rapid economic growth.

On the other hand, cracks can develop in concrete structures over many years of use due to carbon dioxide from the atmosphere penetrating into them along with moisture, causing carbonation, corrosion and expansion due to the penetration of chloride ions from sea breezes and antifreeze droplets, or the expansion of certain silica mineral aggregates as they react with water. These cracks can cause pieces of concrete to spall, or due to the freezing of moisture that has seeped into the concrete.

In attempts to prevent such concrete spalling and deterioration, Patent Documents 1 to 3 propose using a repair material by impregnating a spall-preventing laminated substrate made from a mesh sheet and nonwoven fabric with a curable composition, Patent Document 4 proposes using an inorganic curable composition, and Patent Document 5 proposes using a water-repellent composition.

The ultimate goal is to maintain existing concrete structures in a semi-permanent usable state by implementing these concrete structure protection and spalling prevention methods every 10 to 20 years.

JP 2012-26238 A JP 2013-019146 A Japanese Patent Application Laid-Open No. 2004-149929 Japanese Patent Application Laid-Open No. 2017-186825 JP 2013-193884 A

However, when a water-repellent layer is provided in contact with the concrete structure, or when a water-repellent layer is impregnated into the cured product of the cured composition, the water-repellent components penetrate into the concrete once application is performed. Therefore, even if the repair member is removed and reapplication is attempted, the water-repellent components inside the concrete reduce the adhesive strength of the water-based cured composition, making reapplication impossible.

The present invention was made in consideration of the above-mentioned problems, and aims to provide a repair material and repair method for concrete structures that has sufficient reinforcing strength, suppresses water penetration into concrete structures, maintains water vapor permeability from the concrete structure, and allows for the reapplication of a new water-based hardening composition.

This application includes the following inventions:
(1) A repair component for concrete structures, comprising: a hardening composition containing an aqueous silicate solution and a pozzolan active substance having an electrical conductivity difference of 0.4 mS/cm or more; a laminated substrate; and a waterproof/moisture-permeable layer laminated on the laminated substrate, wherein the laminated substrate includes a sheet-like member formed by combining multifilaments in a multiaxial mesh shape and a resin fiber sheet member, and the waterproof/moisture-permeable layer contains a component that forms a silicone skeleton.

(2) A repair component for a concrete structure as described above, wherein the waterproof and moisture-permeable layer contains at least one component selected from the group consisting of acrylic silicone and modified silicone.

(3) A repair component for a concrete structure as described above, in which the waterproof and moisture-permeable layer has a water absorption rate of 75% or less and a water vapor transmission rate of 20% or more after immersion in water for 24 hours.

(4) A method for repairing a concrete structure, comprising the steps of: preparing a repair member by applying or impregnating a layered substrate with a composition containing a silicate aqueous solution and a pozzolan active substance with an electrical conductivity difference of 0.4 mS/cm or more; curing the repair member; and applying a waterproof/breathable material to the surface of the repair member to form a waterproof/breathable layer, wherein the waterproof/breathable material forms a silicone skeleton.

(5) The method for repairing a concrete structure described above, wherein the waterproof and breathable material contains at least one component selected from the group consisting of acrylic silicone and modified silicone.

The concrete structure repair component and repair method of the present invention provide sufficient repair strength, suppress water penetration into the concrete structure, maintain water vapor permeability from the concrete structure, and allow for the reapplication of a new water-based hardening composition.

1 is a schematic cross-sectional view showing an example of a method for repairing a concrete structure using a concrete structure repair member (two-layer structure + waterproof/moisture-permeable layer) of the present invention. 1 is a schematic cross-sectional view showing an example of a method for repairing a concrete structure using a concrete structure repair member (three-layer structure + waterproof/moisture-permeable layer) of the present invention. 1 is a flow diagram showing an example of a concrete structure repair method of the present invention. 1 is a diagram showing a repair base member used in the concrete structure repair method of the present invention. FIG.

<Repair parts>
A repair member 10 according to an embodiment of the present invention is attached to a concrete structure 5 as shown in FIG. 1, for example, in order to repair the concrete structure 5.

The repair member of the present application comprises a curable composition, a laminated substrate 4, and a waterproof/moisture-permeable layer 6. The curable composition and the laminated substrate 4 may exist separately, but during repair, the curable composition is impregnated into the laminated substrate 4, as described below.

This type of repair member 10 can maintain the inherent fire resistance of the concrete structure while ensuring adhesive strength, and by improving waterproofing while ensuring moisture permeability, it is possible to maintain repair performance over the long term.

(Curable composition)
The curable composition is applied to and/or impregnated into the laminated substrate 4. By applying and/or impregnating the curable composition into the laminated substrate 4 and then curing the curable composition, the concrete structure 5 and the repair member 10 can be bonded together, and by bonding the repair member 10 together, it is possible to prevent concrete pieces from peeling off from deteriorated portions of the concrete structure 5.

The viscosity of the curable composition at 25°C is preferably 400 mPa·s to 3000 mPa·s. This viscosity ensures that the composition can be impregnated into the laminated substrate 4. It also prevents the curable composition from dripping when applied to the concrete structure 5.

A variety of materials can be used for the curable composition, including organic materials such as epoxy resin, polyurethane, polyurea, unsaturated polyester, phenolic resin, or combinations thereof, and inorganic materials such as cement slurry, gypsum, and glass. In particular, the use of inorganic materials can ensure the fire resistance of concrete structures.

A particularly preferred inorganic hardenable composition is a composition containing an aqueous solution of sodium silicate, potassium silicate, lithium silicate, or a mixture thereof, and a pozzolan active substance (hereinafter sometimes referred to as a "geopolymer").

In particular, when sodium silicate and potassium silicate are applied to the surface of the concrete structure 5, they can produce a C-S-H gel with the calcium hydroxide in the concrete, thereby strengthening the adhesive strength between the repair member 10 and the concrete structure 5.

Geopolymers can suppress separation of components in hardenable compositions because the difference in specific gravity between the liquid component consisting of an aqueous silicate solution and the solid component consisting of a pozzolanic active substance is smaller than the difference in specific gravity between the water and cement contained in cement slurry.

When a geopolymer is used in a hardenable composition, the pozzolan active substance preferably has an electrical conductivity difference of 0.4 mS/cm or more, more preferably 0.7 mS/cm or more, and even more preferably 1.2 mS/cm or more.

By achieving this difference in electrical conductivity, sufficient reactivity with the silicate aqueous solution can be ensured, increasing the adhesive strength between the repair member 10 and the concrete structure 5. The difference in electrical conductivity here is an indicator related to the reactivity of the pozzolanic active substance induced by alkaline substances, and refers to the difference in electrical conductivity of the saturated calcium hydroxide aqueous solution before and after the addition of the pozzolanic active substance, obtained using the evaluation method described below.

Pozzolanic active substances are substances that harden when water reacts with calcium oxide, calcium hydroxide, aluminum hydroxide, etc. Examples include silica dust, diatomaceous earth, talc, aerosil, white carbon, kaolin, metakaolin, activated clay, and acid clay. Of these, metakaolin is preferred.

Generally, the pozzolan active substance preferably has a silica content of 40% by weight or more, calculated as _SiO2 , based on the dry solids content of the cured product. The aluminum content derived from the _pozzolan active substance, calculated as _Al2O3 , is preferably 20 to 40% by weight, based on the dry solids content of the cured product.

Pozzolanic active substances may be used as powder as is, or may be activated by methods such as thermal spraying, pulverization and classification, or the application of mechanical energy. These methods may also be used in combination.

The thermal spraying method is the same as that used for ceramic coating. In this thermal spraying method, the material powder is preferably melted at a temperature of 2000°C to 16000°C and sprayed at a speed of 30 m/s to 800 m/s, and methods such as plasma spraying, high-energy gas spraying, and arc spraying are possible. The specific surface area of the obtained powder is preferably 0.1 ^m /g to 100 ^m /g.

Any known method can be used for crushing and classifying. Examples of crushing methods include jet mills, roll mills, and ball mills. Examples of classification methods include sieving, specific gravity, wind force, and wet sedimentation.

Mechanical energy can be applied using a ball media mill, media agitation mill, roller mill, etc., with the applied mechanical energy preferably being between 0.5 kWh/kg and 30 kWh/kg. By using mechanical energy in this range, the powder can be sufficiently activated while also minimizing the load on the equipment.

For example, the total content of sodium, potassium, lithium or a mixture thereof derived from the aqueous silicate solution in the geopolymer is preferably 5% by weight to 30% by weight in terms of M ₂ O (M is sodium, potassium and lithium) relative to the dry solid content of the hardened material obtained from the hardenable composition.

Furthermore, when using an aqueous silicate solution, it is desirable that the numerical value n represented by the following mathematical formula for the aqueous solution be 0.5 to 1.1, and more preferably 0.7 to 1.0.

n = S × M
(S: number of moles of silicon contained in the aqueous solution, M: number of moles of alkali metal contained in the aqueous solution)

(Other ingredients)
In addition to the above components, the curable composition may contain components disclosed in JP-A-2017-186825, JP-A-2017-226955, etc., and additives known in the art. Examples include fillers, modifiers, dispersants, cure time adjusters, pigments, antioxidants, polymer emulsions, etc. These are not particularly limited, and known substances can be used. The filler may be any of those generally used as a filling agent.

Examples include carbon, cellulose, mineral fine powder, and synthetic inorganic crystalline powder. Modifiers include various metal salts that can react with aqueous silicate solutions, such as light-burned magnesium oxide and zinc oxide. Polymer emulsions include acrylic rubber, styrene-butadiene rubber, and mixtures thereof. These additives can be used in any amount as long as they do not impair the intended function of the curable composition. In particular, it is preferable that the polymer emulsion be formulated so that the polymer solids weight is 3% to 10% by weight based on the total weight of the dry solids of the curable composition.

This improves the fluidity of the curable composition, improves the adhesive strength of the cured product, and suppresses drying shrinkage of the cured product.

(Laminated base material)
The laminated substrate 4 is constructed by laminating a sheet-like member in which multifilaments are combined in a multiaxial mesh shape and a resin fiber sheet-like member. For example, when the first layer 1 is a sheet-like member in which multifilaments are combined in a multiaxial mesh shape and the second layer 2 is a resin fiber sheet-like member, the laminated substrate 4 is preferably constructed such that the first layer 1 and the second layer 2 are laminated in this order from the concrete structure 5 side, as shown in Fig. 1 .

Furthermore, as shown in Figure 2, when the repair member 11 has a laminated structure in which the laminated base material 14 has three or more layers, the repair member 11 may have a configuration in which a third layer 3 (described below), a first layer 1, and a second layer 2 are laminated in this order from the concrete structure 5 side.

The laminated base materials 4, 14 may each have one first layer and one second layer, or two or more layers. Furthermore, when two or more layers of either or both are laminated, the first layers may be laminated together and/or the second layers may be laminated together, but it is preferable that the first layers and second layers are laminated alternately. Furthermore, the resin fiber sheet-like member may have a two-layer structure, or only one layer may be a resin fiber sheet, or two or more layers may be resin fiber sheets, or only resin fiber sheets may be laminated.

(Sheet-like member in which multifilaments are combined in a multiaxial mesh form)
As shown in Figures 1 and 2, the first layer 1 is preferably a sheet-like member in which multifilaments are combined in a multiaxial mesh shape. The multifilaments are preferably formed using long fibers and preferably have a tensile strength of 150 N or more. The value X represented by formula (1) of the sheet-like member in which multifilaments are combined in a multiaxial mesh shape is preferably 2.0 or more, more preferably 2.5 or more, 2.8 or more, or 3.0 or more.

X = A × B (1)
Here, A represents the tensile strength (kN/50 mm) of the sheet-like member in one direction, 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. B may range from 2 to 4. Of these, A is preferably 0.75 kN or more, and B is preferably 2 to 3.

This first layer 1 can fulfill the function of a load-bearing layer that catches concrete pieces that fall from the concrete structure 5.

Examples of materials for the first layer 1 include polyester, polyolefin, vinylon, aramid, carbon fiber, and glass fiber. Of these, a vinylon mesh sheet or a glass mesh sheet is preferable. The glass fiber is preferably glass yarn or roving. Glass yarn is made by twisting glass fibers to form a ply-twisted yarn, and roving is made by bundling glass fibers. Examples of weaving methods for the multiaxial mesh include plain weave, twill weave, leno weave, and braided fabric. The weaving direction of the multiaxial mesh may be a biaxial or more multiaxial fabric with perpendicular directions.

The thickness of the first layer 1 is preferably 0.1 mm or more and 1.5 mm or less, and more preferably 0.3 mm or more and 1 mm or less.

The first layer 1 preferably has a basis weight of 50 g/mm ² or more, more preferably 60 g/mm ² or more, and even more preferably 75 g/mm ² or more.

By setting the weight within this range, the tensile strength can be improved, preventing breakage when concrete pieces fall off and ensuring sufficient bearing capacity of the repair component.

The first layer 1 is preferably a biaxial woven fabric with an opening size of 5 mm or more and 25 mm or less. By setting the opening size within this range, the adhesive strength between the second layer 2 and the concrete structure 5 (described below) or the adhesive strength between the second layer 2 and the third layer 3 can be improved, ensuring sufficient strength of the repair material. In addition, by setting the number of long fibers per unit area of the first layer 1 to an appropriate number, the resistance of the first layer 1 when it breaks through the second layer 2 can be increased, ensuring sufficient strength of the repair material.

The first layer 1 is more preferably a biaxial woven fabric with a mesh size of 5 mm to 25 mm and a basis weight of 50 g/ ^mm² or more. Alternatively, the first layer 1 may be a multiaxial woven fabric with an opening ratio equivalent to that of the biaxial woven fabric. In particular, the first layer 1 is more preferably a biaxial or triaxial mesh sheet-like member made by combining multifilaments with a tensile strength of 150 N or more with a mesh size of 5 mm to 25 mm.

(Resin fiber sheet member)
1 and 2, the second layer 2 is preferably a resin fiber sheet-like member. The tear strength of the second layer 2 is preferably 2.0 N or more. By setting the tear strength to 2.0 N or more, the second layer 2 can fulfill the function of a reinforcing layer that increases the resistance when the first layer 1 breaks through the second layer 2.

The second layer 2 may be in the form of a woven fabric, a nonwoven fabric, or the like.
Examples of materials for the second layer 2 include polyester, polyolefin, vinylon, aramid, carbon fiber, and glass fiber. Among these, polypropylene nonwoven fabric or glass nonwoven fabric is preferred, and long-fiber nonwoven fabric is particularly preferred. Glass nonwoven fabric has excellent compatibility with the curable composition, allowing the curable composition to easily penetrate the fabric, and when the curable composition is cured, the repair material can be firmly fixed to the concrete structure. Suitable glass nonwoven fabrics include chopped strand mat, glass paper, and felt.

When using polypropylene nonwoven fabric, the fibers can be subjected to a hydrophilic treatment to increase compatibility with the curable composition. The hydrophilic treatment can be carried out using any method known in the art.

The thickness of the second layer 2 is preferably 0.1 mm or more and 1.0 mm or less, and more preferably 0.15 mm or more and 0.5 mm or less. By setting the thickness within this range, the second layer 2 functions as a reinforcing layer that increases resistance when the first layer 1 breaks through the second layer 2, while also reducing the amount of curable composition impregnated into the substrate, which is economically advantageous.

The second layer 2 preferably has a basis weight of 30 g/mm ² or more, more preferably 50 g/mm ² or more, and even more preferably 60 g/mm ² or more. By setting the basis weight within this range, the tensile strength can be improved, and sufficient bearing capacity of the repair material can be ensured without causing breakage when concrete pieces peel off.

The second layer 2 is preferably a biaxial woven fabric with an opening size of 3 mm or more and 30 mm or less. By keeping the opening size within this range, the adhesive strength with the third layer 3 (described below) can be improved, ensuring sufficient strength of the repair material. Furthermore, by setting the number of long fibers per unit area of the first layer 1 to an appropriate number, the resistance of the first layer 1 when it breaks through the second layer 2 can be increased, ensuring sufficient strength of the repair material.

The second layer 2 is preferably a multifilament with a tensile strength of 10 N or more, and more preferably a biaxial or triaxial mesh sheet-like member. It is also preferably a sheet-like member with a tear strength of 2.0 N or more.

When the laminated substrate has a two-layer structure consisting of a first layer 1 and a second layer 2, or a laminated structure of more than two layers, it is preferable that the first layer 1 is a sheet-like member made by combining multifilaments in a multiaxial mesh pattern, and the second layer 2 is a resin fiber sheet-like member with a tear strength of 2.0 N or more. It is also preferable that the first layer 1 is a sheet-like member made by combining multifilaments with a tensile strength of 150 N or more in a multiaxial mesh pattern with a mesh opening of 5 mm to 25 mm, and the second layer 2 is a resin fiber sheet-like member with a tear strength of 2.0 N or more.

(Third layer, etc.)
When the laminated base material has a three or more layer structure, such as the laminated base material 14 shown in Fig. 2, as long as the first layer 1 is placed on the concrete structure 5 side and the second layer 2 is placed on the outside, the third and subsequent layers may be placed anywhere and in any number, without being limited to the configuration shown in Fig. 2. Such a laminated structure can achieve both the strength of the repair material and its adhesion to the concrete structure.

These third and subsequent layers may be selected from the first layer 1 and second layer 2 described above, or may be any layer used in the relevant field. Considering ease of use, economy, etc., a two-layer structure or a three-layer structure is preferred. These third and subsequent layers may be selected from the first and second layers described above, or may be any layer used in the relevant field.

The third layer 3 preferably has a porosity of 90% or more and is a resin fiber sheet-like member. This ensures the hardenable composition can be impregnated into it, and when the third layer 3 is placed in contact with the concrete structure 5 as shown in Figure 2, the third layer 3 can fulfill its function as an adhesive layer that improves the adhesive strength between the repair member 11 and the concrete structure 5.

The thickness of the third layer 3 is preferably 0.1 mm or more and 1.5 mm or less, and more preferably 0.2 mm or more and 0.8 mm or less. By keeping the thickness of the third layer 3 within this range, the adhesive strength between the repair members 10, 11 and the concrete structure 5 is ensured, and the amount of hardenable composition impregnated into the laminated base materials 4, 14 can be reduced, which is economically advantageous.

(Lamination integration)
The laminated substrates 4 and 14, which are formed by laminating at least two layers of sheet-like members, may be integrated by impregnating them with a curable composition, but it is preferable to integrate them in advance, as this can prevent the sheet members from shifting during application and impregnation.

Methods of integration include mechanical fiber entanglement and chemical bonding, such as fulling, needle punching, chemical bonding, thermal bonding, and hydroentanglement.

Regardless of the composition of the laminated substrate, the amount of curable composition impregnated into the laminated substrate should be such that the curable composition is uniformly retained throughout the laminated substrate, and it is preferable to adjust the amount so that the entire laminated substrate is firmly integrated upon curing of the curable composition. For example, the mass ratio of laminated substrate to curable composition is preferably approximately 1:4 to 1:12, and more preferably 1:4 to 1:10.

(Waterproof and breathable layer)
The waterproof and moisture-permeable layer may be a layer formed by impregnating a waterproof and moisture-permeable material into a suitable sheet-like member, or may be a layer obtained by applying a waterproof and moisture-permeable material to a laminated substrate 4, 14 that has been coated and/or impregnated with a curable composition.

In this case, as shown in Figures 1 and 2, the waterproof and moisture-permeable layer 6 is preferably disposed on the surface of the laminated substrate 4, 14 opposite the concrete structure 5. By disposing such a waterproof and moisture-permeable layer, the waterproofing properties of the repair members 10, 11 can be improved while ensuring the moisture permeability of the repair members 10, 11. As a result, the repair members 10, 11 themselves can prevent concrete pieces from peeling off from deteriorated portions of the concrete structure 5 for an extended period of time.

Waterproof and breathable materials containing components that form a known silicone skeleton can be used.

Examples of waterproof and breathable materials that form a silicone skeleton include those containing structures such as acrylic silicone and modified silicone.

Specific examples of acrylic silicone waterproof and breathable materials include those manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd. under the trade name Diestender 2000B Clear.

Modified silicone-based waterproof and breathable materials include a mixture containing a modified silicone resin, an epoxy resin, a silanol condensation catalyst, and an epoxy resin curing agent as an adhesive resin composition. While there are no particular limitations on the modified silicone resin, a moisture-curing modified silicone resin is preferred, which contains a hydrolyzable silicon group. The modified silicone resin containing a hydrolyzable silicon group may be a polymer of a monomer selected from the group consisting of an alkylene oxide component, an olefin component, and an acrylic component, and the polymer may be either a homopolymer or a copolymer.

The waterproof and moisture-permeable material can be used in any amount as long as it does not impair the intended function of the curable composition. For example, the amount can be appropriately set depending on the size of the laminated substrate, and the application amount can be 3 g/m ² to 1000 g/m ² relative to the area of the laminated substrate, with 5 g/m ² to 600 g/m ² being preferred. From another perspective, the water absorption rate after 24 hours is preferably 75% or less, more preferably 70% or less, and even more preferably 60% or less. The water vapor transmission rate is preferably 20% or more, more preferably 30% or more, and even more preferably 50% or more.

Furthermore, it is preferable that the water absorption rate after 24 hours be 75% or less and the water vapor transmission rate be 20% or more, more preferable that the water absorption rate after 24 hours be 70% or less and the water vapor transmission rate be 30% or more, and even more preferable that the water absorption rate after 24 hours be 60% or less and the water vapor transmission rate be 50% or more. By laminating a waterproof/moisture-permeable layer with such properties to the laminate substrate, the above-mentioned effects can be further enhanced.

<Method for repairing concrete structures>
The concrete structure repair method of this embodiment will be described below. Fig. 3 is a flow chart showing the concrete structure repair method.

The concrete structure repair method of the present application can be carried out using the above-mentioned concrete structure repair component. Specifically, it includes the steps of preparing a repair base component by applying or impregnating a layered substrate with a composition containing a silicate aqueous solution and a pozzolan active substance with an electrical conductivity difference of 0.4 mS/cm or more (Step S10), attaching the repair base component to the concrete structure (Step S20), hardening the attached repair base component (Step S30), and applying a waterproof/breathable material to the surface of the hardened repair base component to form a waterproof/breathable layer (Step S40).

This repair method eliminates the need for repeated application and drying of a curable liquid composition such as an adhesive or binder, as has been done in the past, making the process simple, efficient, and easy to use.

(Preparation of foundation materials for repair)
To prepare a repair base member, first, the above-described curable composition is prepared. Materials constituting the laminated substrate are also prepared. The curable composition may be applied to or impregnated into the laminated substrate after the laminated substrate is formed, or the laminated substrate may be formed by impregnating the curable composition with the curable composition after the impregnation, or the curable composition may be impregnated while the laminated substrate is being formed. The curable composition may also be applied to or impregnated into the laminated substrate either before or after the laminated substrate is attached to the target concrete structure.

Methods for applying or impregnating a laminated substrate with a curable composition include, for example, (1) a hand layup method in which application is performed by hand using a roller; (2) a method of applying or impregnating by spraying; (3) a method in which the thickness of the laminated substrate is defined using a mold and then the curable composition is applied to and impregnated into the laminated substrate by pressing; (4) a method in which the thickness of the laminated substrate is defined using reduced pressure and then the curable composition is applied to and impregnated into the laminated substrate by reduced pressure injection; (5) a method in which the laminated substrate is immersed in the curable composition, the laminated substrate is continuously impregnated with the curable composition, and then the thickness of the laminated substrate is defined using a roll; and (6) a method in which continuous application and impregnation are performed by roll transfer. These methods may also be used in combination.

To improve workability during impregnation and to prevent dirt from adhering to the impregnated sheet and to prevent the impregnated sheets from adhering to each other, the front and back surfaces of the laminated substrate may be covered with a resin protective film. This protective film can be removed before attaching the sheet to the concrete structure.

(Attachment process)
The resulting repair base member is attached to the concrete structure. At this time, it is important to remove any air bubbles that have entered between the repair base member and the surface of the concrete structure, particularly in order to improve adhesion between the repair base member and the surface of the concrete structure. A suitable method for removing air bubbles is to use a roll or metal spatula to expel the air bubbles to the outside of the repair member. Figure 4 shows the repair base member 20 attached to the concrete structure 5.

(Curing process)
The hardening of the curable composition impregnated into the repair member is carried out by placing the repair base member in close contact with the concrete structure (see Figure 4). From the viewpoint of ensuring sufficient time for the curable composition to be impregnated into the surface of the concrete structure, the curing time of the curable composition is preferably 30 to 300 minutes, more preferably 45 to 240 minutes. The curing time can be adjusted by the amount and type of curing catalyst in the case of organic materials, the amount of water contained in the case of inorganic materials, and, particularly in the case of geopolymers, the content of sodium, potassium, lithium, or a mixture thereof derived from the silicate aqueous solution, the ratio of SiO ₂ to M ₂ O (M: sodium, potassium, and lithium) derived from the silicate aqueous solution (SiO ₂ /M ₂ O), the difference in electrical conductivity of the pozzolanic active substance, the aluminum content, etc. Once the hardening of the curable composition is complete, the repair base member is fixed to the concrete structure, completing the repair of the concrete structure.

(Formation of waterproof and breathable layer)
The waterproof and moisture-permeable layer can be formed by applying a curable composition to a laminated substrate (also referred to as a repair base member in this embodiment) impregnated with the curable composition while the laminated substrate is in close contact with the concrete structure. In particular, it is preferable to impregnate the laminated substrate with the curable composition and apply the waterproof and moisture-permeable material after the curable composition has hardened.
By applying a waterproof/moisture-permeable material to the surface 20a of the laminated substrate 4 (repair base member 20) impregnated with the curable composition shown in Fig. 4, the waterproof/moisture-permeable layer 6 can be arranged in a layered form on the surfaces of the repair members 10, 11 as shown in Fig. 1 and Fig. 2. Note that Fig. 4 shows the laminated substrate 4 of Fig. 1 including the first layer 1 and the second layer 2, but the same applies to the laminated substrate 14 of Fig. 2 including the first layer 1, the second layer 2, and the third layer 3.

For example, from the viewpoint of the impregnation of the curable composition into the cured product or the laminated substrate, it is preferable to perform the treatment after the curing of the curable composition has progressed and the surface moisture content has fallen below 8%. From another viewpoint, it is preferable to perform the treatment within 7 days after the preparation of the curable composition, and more preferably after 30 minutes to 24 hours.

Application can be done using common methods, such as brush, roller, spray gun, plastering, etc.

In this way, by applying a waterproof and moisture-permeable material to the surface of a repair base member made of a laminated substrate impregnated with a curable composition, a repair member can be provided on the surface of a concrete structure.

The concrete structure repair component and repair method of the present invention will be described in more detail below using examples, but the present invention is not limited to these.

Example 1
A laminated substrate was prepared by laminating a triaxial mesh sheet (basis weight 90 g/ ^m2 , mesh size 8 mm, thickness 0.35 mm, X = 3.0) made of vinylon multifilament onto a hydrophilized polypropylene spunbond nonwoven fabric (basis weight 30 g/ ^m2 , thickness 0.2 mm, tear strength 16 N).

The triaxial mesh sheet corresponds to the "first layer", and the spunbond nonwoven fabric with a basis weight of 30 g/m ² corresponds to the "second layer".

100 g of a JIS K1408 No. 3 sodium silicate solution, 50 g of a 30% sodium hydroxide solution (n=0.7), and 15 g of latex (product name: SR-151, manufactured by Nippon A&L Co., Ltd.) were stirred for 24 hours to obtain a silicate solution. A curable composition was prepared by mixing this with 130 g of calcined kaolin (product name: SP-33, manufactured by BASF, electrical conductivity difference: 1.1 mS/cm) that had been processed for 3 hours at 3.3 kW/kg in an ultra-fine mill (using zirconia balls with a diameter of 10 mm, a ball filling rate of 85%, and a mixture of 25% triethanolamine and 75% ethanol with 0.6% metakaolin added as a grinding aid) at 10°C. The viscosity of the resulting curable composition was 1000 Pa·s.

The content of Na ₂ O (equivalent value) in the cured product was 11.3 wt % and the content of Al ₂ O ₃ (equivalent value) was 30.9 wt % based on the total weight of the cured product.

A 100mm x 100mm sheet laminate substrate prepared above was impregnated with 11g of the curable composition in a 23°C environment, allowed to cure in a 23°C environment, and then an acrylic silicone waterproof and moisture-permeable material (Dainichiseika Color & Chemicals Mfg. Co., Ltd., product name: Diestender 2000B Clear) was applied evenly three times at 2-hour intervals in 1g increments to form a waterproof and moisture-permeable layer, thereby producing the concrete structure repair component of Example 1.

Example 2
The sheet laminate substrate prepared in Example 1, 100 mm x 100 mm, was impregnated with 11 g of the curable composition prepared in Example 1 and cured.

A waterproof and moisture-permeable layer was formed by uniformly applying 4.5 g of a modified silicone-based waterproof and moisture-permeable material containing modified silicone resin, calcium carbonate, calcium oxide, and titanium oxide, to prepare the repair member for the concrete structure of Example 2. All of the above work was carried out in an environment of 23°C.

Comparative Example 1
A repair member for a concrete structure was produced in the same manner as in Example 1, except that the application of the acrylic silicone waterproof and moisture-permeable material was omitted.

(Water absorption rate after immersion for 24 hours)
The water absorption performance of each example and comparative example was determined with reference to JIS A1404 "Test Methods for Cement Waterproofing Agents for Construction," Section 7.5 "Water Absorption Test." Specifically, the repair member prepared in each example and comparative example was attached to a 100 mm x 100 mm x 30 mm concrete surface. The side in contact with the repair member was waterproofed with aluminum tape and the terminals were sealed with silicone (specifically, Silicone JX, manufactured by Sekisui Fuller Co., Ltd.). The repair member surface was partially immersed in water to a depth of 20 mm, and the water absorption after 24 hours was measured. The results are shown in Table 1. The "water absorption" value in Table 1 is the average of three measurements. The water absorption rate after 24 hours of immersion was defined as the water absorption rate of each example and comparative example divided by the water absorption rate of Comparative Example 1. In other words, the water absorption rate was determined as the ratio of the water absorption rate after 24 hours of immersion in water with and without a waterproof/moisture-permeable layer.

If the water absorption rate is 75% or less, preferably 60% or less, after 24 hours of immersion, the waterproofing performance will be equivalent to that of commercially available waterproof coatings, and sufficient waterproofing will be achieved against rainwater penetration.

(Water vapor permeability)
The water vapor permeability of each Example and Comparative Example was evaluated with reference to JIS A1171 "Test Methods for Polymer Cement Mortar" 7.12 "Moisture Permeability Test (Test by Moisture Absorption)." Specifically, the repair member prepared in each Example and Comparative Example was attached to a 68 mm diameter mortar, and the mortar with the repair member attached was fixed in a JIS-specified aluminum cup with epoxy adhesive so that there were no gaps. The water vapor permeability was measured based on the moisture absorption of calcium chloride sealed inside the aluminum cup. The results are shown in Table 1. The "water vapor permeability" value in Table 1 is the average of three measurements. The water vapor permeability of each Example and Comparative Example divided by the water vapor permeability of Comparative Example 1 was defined as the water vapor permeability rate.

When the water vapor transmission rate is 20% or higher, preferably 50% or higher, it achieves moisture permeability equivalent to that of commercially available moisture-permeable materials for concrete, and does not hinder the evaporation of moisture from within the concrete even when applied to the laminated base material of repair components for concrete structures.

From the results of evaluating the water absorption rate and water vapor permeability of the repair members of each example after 24 hours of immersion, it was confirmed that the concrete repair member of the present invention can improve the waterproofing properties of repair members for concrete structures while ensuring moisture permeability.

The repair member of the present invention can extend the lifespan of concrete structures.

DESCRIPTION OF SYMBOLS 1 First layer 2 Second layer 3 Third layer 10, 11 Repair member 4, 14 Laminated substrate 5 Concrete structure 6 Waterproof/moisture-permeable layer 20 Repair base member

Claims (6)

A repair member that is attached to the surface of a concrete structure,
a hardening composition comprising an aqueous silicate solution and a pozzolan active substance having an electrical conductivity difference of 0.4 mS/cm or more;
A laminated substrate; and a waterproof/breathable layer laminated on the laminated substrate,
The laminated base material includes a sheet-like member in which multifilaments are combined in a multiaxial mesh shape, and a resin fiber sheet member,
the curable composition is contained in the laminate substrate;
The waterproof and moisture-permeable layer contains a component that forms a silicone skeleton,
The waterproof moisture-permeable layer is disposed on the opposite side of the laminated substrate from the concrete structure,
The laminated substrate containing the cured composition does not contain a component that forms the silicone skeleton.
Repair material for concrete structures. The concrete structure repair member according to claim 1, wherein the waterproof/moisture-permeable layer contains at least one component selected from the group consisting of acrylic silicone and modified silicone. A repair component for a concrete structure as described in claim 1 or claim 2, wherein the waterproof and moisture-permeable layer has a water absorption rate of 75% or less and a water vapor permeability of 20% or more after immersion in water for 24 hours. A method for repairing a concrete structure, comprising:
a step of preparing a repair base member by applying or impregnating a layered substrate with a composition containing a silicate aqueous solution and a pozzolan active substance having an electrical conductivity difference of 0.4 mS/cm or more;
A step of hardening the repair base member attached to the surface of the concrete structure;
and applying a waterproof and moisture-permeable material to the surface of the hardened repair base member opposite the concrete structure to form a waterproof and moisture-permeable layer,
The laminated base material includes a sheet-like member in which multifilaments are combined in a multiaxial mesh shape, and a resin fiber sheet member,
The waterproof and breathable material forms a silicone skeleton,
The repair base member does not contain a component that forms the silicone skeleton of the waterproof and breathable material.
Methods for repairing concrete structures. The concrete structure repair method described in claim 4, wherein the waterproof and moisture-permeable material contains at least one component selected from the group consisting of acrylic silicone and modified silicone. The waterproof and moisture-permeable material is applied after the moisture content of the surface of the repair base member falls below 8%.
The method for repairing a concrete structure according to claim 4.