Method for repairing concrete structures

Abstract

To provide a method for repairing a concrete structure capable of improving the adhesion of a repair material to the surface of the concrete structure.SOLUTION: In the method for repairing a concrete structure 100, a composition containing an aqueous silicate solution is coated on the surface of the concrete to be repaired in step S20 (coating step), a repair material 10 in which a laminate 4 is coated or impregnated with a composition containing an aqueous silicate solution and a pozzolan active substance is pasted on the surface of the concrete after step S10 in step S30 (pasting step), and the repair material 10 is hardened after the step S30 in step S40 (hardening step). The molar ratio of the silicate aqueous solution in the step S30 is greater than or equal to the molar ratio of the silicate aqueous solution in the step S20.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a method for repairing a concrete structure. [Background technology]

[0002] Concrete structures have the advantages of being high strength, easy to work with, and inexpensive, so many concrete structures were built in Japan, especially during the period of rapid economic growth.Although concrete structures are highly durable, they can become neutralized over many years of use when carbon dioxide from the atmosphere penetrates into them along with moisture, or can become corroded and expanded by the penetration of sea breezes and chloride ions contained in droplets of antifreeze, leading to cracks.

[0003] Methods for repairing such concrete structures are disclosed in, for example, Patent Documents 1 to 3.

[0004] Fig. 4 is a cross-sectional view showing the concrete structure repair methods disclosed in Patent Documents 1 to 3. Fig. 4 shows a state in which a repair material 1010, which is a laminate of two or more layers of sheet-like members impregnated with a hardenable liquid component, is adhered to a concrete structure 100. Patent Document 3 also discloses a repair method in which a repair material, which is a laminate impregnated with a hardenable liquid component, is adhered to a concrete structure and then an aqueous modifier solution is applied to the concrete structure. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6641106 [Patent Document 2] Japanese Patent Application Publication No. 2017-186825 [Patent Document 3] Japanese Patent Application Publication No. 2019-206896 Summary of the Invention [Problem to be solved by the invention]

[0006] In the conventional concrete structure repair method as described above, there is room for improvement in the adhesion of the sheet to the concrete structure.

[0007] The present disclosure has been made to solve such problems, and aims to provide a method for repairing a concrete structure that can improve the adhesion of a repair material to the surface of the concrete structure. [Means for solving the problem]

[0008] To achieve the above object, the first disclosed method for repairing a concrete structure includes an application step, an attachment step, and a curing step. In the application step, a composition containing a first aqueous silicate solution is applied to the surface of the concrete to be repaired. In the attachment step, a repair material formed by applying or impregnating a laminate with a composition containing a second aqueous silicate solution and a pozzolan active substance is attached to the surface of the concrete after the application step. In the curing step, the repair material is cured after the attachment step. The molar ratio of the first aqueous silicate solution and the molar ratio of the second aqueous silicate solution are the molar ratio of SiO to M2O (SiO2 / M2O), where M is at least one alkali metal selected from lithium, sodium, and potassium. The molar ratio of the second aqueous silicate solution is equal to or greater than the molar ratio of the first aqueous silicate solution.

[0009] Since calcium is often eluted from deteriorated concrete, simply attaching a repair material to the surface of the concrete may weaken the adhesiveness of the repair material composition to the concrete surface.

[0010] In the concrete structure repair method of the present disclosure, a composition containing a first aqueous silicate solution is applied as a primer before a repair material is applied to the surface of concrete.

[0011] This allows the composition containing the first silicate aqueous solution to react with the deteriorated concrete and gradually harden, improving the adhesion of the applied repair material and making it less likely for the repair material to peel off even on deteriorated concrete structures.

[0012] Furthermore, the second silicate aqueous solution used in the repair material has a molar ratio equal to or greater than that of the first silicate aqueous solution used in the application step.

[0013] The molar ratio (SiO2 / M2O) represents the ratio of SiO2 derived from the silicate solution to M2O (M is an alkali metal, etc.), and is a number related to the reactivity with the pozzolanic active substance. The smaller the number, the higher the reactivity.

[0014] By using a silicate aqueous solution with a molar ratio equal to or greater than that of the first silicate aqueous solution used in the application process as the second silicate aqueous solution used in the repair material, in other words, by using a silicate aqueous solution with a molar ratio smaller than that of the second silicate aqueous solution used in the repair material as the first silicate aqueous solution used in the application process, it is possible to prevent the first silicate aqueous solution from mixing with the second silicate aqueous solution in the pasting process, thereby reducing the reactivity of the second silicate aqueous solution and preventing interference with the hardening of the repair material.

[0015] In addition, the primer (composition containing the first silicate aqueous solution) that forms the base for attaching the repair material is inorganic, so it is non-flammable and does not interfere with the non-flammable performance of the repair material. Furthermore, because the composition containing the first silicate aqueous solution is inorganic, it does not form a film or the like and does not interfere with the moisture permeability of the repair material.

[0016] The second disclosed method for repairing a concrete structure is the first disclosed method for repairing a concrete structure, wherein the molar ratio of the first silicate aqueous solution is 0.5 or more and 1.8 or less, and the molar ratio of the second silicate aqueous solution is 0.8 or more and 2.2 or less.

[0017] This allows the aqueous silicate solution to be used as a primer and a hardener.

[0018] The concrete structure repair method of the third disclosure is the concrete structure repair method of the first or second disclosure, in which the laminate has a first layer and a second layer. The first layer is a sheet-like layer made of multifilaments combined in a multiaxial mesh shape. The second layer is a sheet-like layer made of polypropylene spunbond nonwoven fabric. The first layer and second layer are arranged in this order from the surface side of the concrete.

[0019] This allows repairs to be carried out by applying or impregnating the laminate with a composition containing an aqueous silicate solution and a pozzolan active substance and then attaching it to a concrete structure.

[0020] A fourth disclosed method for repairing a concrete structure is the third disclosed method for repairing a concrete structure, wherein the laminate further comprises a third layer. The third layer is in the form of a sheet made of glass nonwoven fabric and placed on the surface side of the concrete of the first layer.

[0021] This allows the repair material to have both strength and adhesion to the concrete.

[0022] A concrete structure repair method according to a fifth disclosure is the concrete structure repair method according to any one of the first to fourth disclosures, further comprising a scraping step, in which the surface of the concrete is scraped prior to the first application step.

[0023] This can further improve the adhesion of the repair material. [Effects of the Invention]

[0024] According to the present disclosure, it is possible to provide a method for repairing a concrete structure that can improve the adhesion of a repair material to the surface of the concrete structure. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a diagram showing a state in which a concrete structure has been repaired using a repair material (three-layer structure) according to an embodiment of the present disclosure. [Figure 2] FIG. 1 is a diagram showing a state in which a concrete structure has been repaired using a repair material (two-layer structure) according to an embodiment of the present disclosure. [Figure 3] 1 is a flow diagram showing a concrete structure repair method according to an embodiment of the present disclosure. [Figure 4] FIG. 1 is a diagram showing a state in which a concrete structure has been repaired using a conventional method for repairing a concrete structure. DETAILED DESCRIPTION OF THE INVENTION

[0026] The concrete structure repair method according to the present disclosure will be described below. (Repair material 10, 10') As shown in Fig. 1, a repair material 10 of the present disclosure is used to repair a concrete structure 100. The repair material 10 comprises a liquid curable composition and a laminate 4 formed by laminating at least two layers of sheet-like members. The laminate 4 and the curable composition may be present separately, but during repair, the curable composition is impregnated into the laminate 4, as described below.

[0027] As shown in Fig. 1, an impregnating material layer 5 is formed on the surface 100s of a concrete structure 100 to which a repair material 10 is to be applied. The impregnating material layer 5 is formed by impregnating the concrete structure 100 with a primer, which will be described later. By providing the impregnating material layer 5, the adhesive strength of the repair material 10 can be improved.

[0028] As shown in Figure 1, by applying the repair material 10 to the portion of the surface 100s of the concrete structure 100 where the impregnating material layer 5 is formed, the hardenable composition of the repair material 10 is applied and impregnated onto the surface of the concrete structure 100. Then, the hardenable composition hardens or bonds with the concrete structure, allowing the concrete structure 10 to be repaired with the repair material 10.

[0029] (Laminates 4, 4´) The laminate 4 of the repair material 10 is formed by laminating two or more layers of sheet-like members.

[0030] For example, the laminate 4 of the repair material 10 shown in Fig. 1 includes a third layer 3 disposed on an impregnating material layer 5 formed on a concrete structure 100, a first layer 1 disposed on the third layer 3, and a second layer 2 disposed on the first layer 1. The third layer 3, the first layer 1, and the second layer 2 are laminated in this order from the concrete structure 100 side.

[0031] Furthermore, the repair material 10 is not limited to the repair material 10 shown in Fig. 1, and may have a configuration such as a repair material 10' shown in Fig. 2. The laminate 4' of the repair material 10' comprises a first layer 1 disposed on the impregnating material layer 5 of the concrete structure 100, and a second layer 2 disposed on the first layer 1. The first layer 1 and the second layer 2 are disposed in this order from the concrete structure 100 side.

[0032] (first layer 1) The first layer 1 is preferably a sheet-like member in which multifilaments are combined in a multiaxial mesh shape. The multifilaments are preferably made 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.

[0033] X = A × B (1) Here, A represents the tensile strength (kN / 50 mm) of the sheet-shaped member in one direction, and B represents the number of axes of the sheet-shaped 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.

[0034] With this configuration, the first layer 1 can fulfill the function of a load-bearing layer that receives concrete pieces that fall from a concrete structure.

[0035] 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 long glass fibers are preferably glass yarn or roving. Glass yarn is made by twisting glass fibers to form a ply 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 orthogonal biaxial or more multiaxial woven fabric.

[0036] 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.

[0037] The first layer is 50g / mm 2 It is preferable that the weight is 60 g / mm or more. 2 More preferably, it is 75 g / mm or more, and even more preferably, it is 75 g / mm 2 That's all.

[0038] By setting the weight per unit area within this range, the tensile strength can be improved, and sufficient bearing capacity of the repair materials 10, 10' can be ensured without causing breakage when concrete pieces fall off.

[0039] 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 100 (described later) or between the second layer 2 and the third layer 3 can be improved, ensuring sufficient strength of the repair materials 10, 10'. 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 materials 10, 10'.

[0040] The first layer 1 has an opening of 5 mm or more and 25 mm or less, and is 50 g / mm 2 It is more preferable that the first layer 1 is a biaxial woven fabric having a basis weight of 150 N or more. Alternatively, it may be a multiaxial woven fabric having an opening ratio equivalent to that of the biaxial woven fabric. In particular, it is more preferable that the first layer 1 is a biaxial or triaxial mesh sheet member made by combining multifilaments having a tensile strength of 150 N or more with an opening size of 5 mm or more and 25 mm or less.

[0041] (Second layer 2) The second layer 2 is preferably a liquid-permeable sheet-like member. The tear strength of the liquid-permeable sheet-like member 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.

[0042] The second layer 2 may be in the form of a woven fabric, a nonwoven fabric, or the like. The second layer 2 may be made of a material such as polyester, polyolefin, vinylon, aramid, carbon fiber, or glass fiber. Among these, a polypropylene nonwoven fabric or a glass nonwoven fabric is preferred, and a 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 glass nonwoven fabric, and when the curable composition is cured, the repair material 10, 10' can be firmly fixed to the concrete structure 100. Suitable glass nonwoven fabrics include chopped strand mat, glass paper, and felt.

[0043] When using polypropylene nonwoven fabric, the fibers may be subjected to a hydrophilization treatment to enhance compatibility with the curable composition. The hydrophilization treatment may be carried out by any method known in the art.

[0044] 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 fulfills its function as a reinforcing layer that increases the resistance when the first layer 1 breaks through the second layer 2, and also makes it possible to reduce the amount of the curable composition impregnated into the laminates 4, 4', which is economically advantageous.

[0045] The second layer 2 is 30 g / mm 2 It is preferable that the weight is 50 g / mm or more. 2 More preferably, it is 60 g / mm or more. 2 By setting the weight per unit area within this range, the tensile strength can be improved, and sufficient bearing strength of the repair materials 10, 10' can be ensured without causing breakage when concrete pieces peel off.

[0046] 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 setting the opening size within this range, the adhesive strength with the third layer 3 (described later) can be improved, and sufficient strength of the repair materials 10, 10' can be ensured. 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, and sufficient strength of the repair materials 10, 10' can be ensured.

[0047] The second layer 2 is preferably a multifilament having a tensile strength of 10 N or more, more preferably a biaxial or triaxial mesh sheet member, and is preferably a sheet member having a tear strength of 2.0 N or more.

[0048] The repair material 10, 10' has a two-layer structure of a first layer 1 and a second layer 2 or a laminated structure of more than one layer. In this case, it is preferable that 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 sheet-like member having a tear strength of 2.0 N or more. Furthermore, in the repair materials 10 and 10', it is preferable that the first layer 1 is a sheet-like member in which multifilaments with a tensile strength of 150 N or more are combined in a multiaxial mesh shape with an opening of 5 mm or more and 25 mm or less, and the second layer 2 is a sheet-like member having a tear strength of 2.0 N or more.

[0049] (Third layer 3) The third layer 3 is preferably a liquid-permeable sheet-like member having a porosity of 90% or more, which ensures impregnation of the hardenable composition and thus fulfills the function of an adhesive layer that improves the adhesive strength between the repair material 10 and the concrete structure 100.

[0050] The third layer 3 may be in the form of a nonwoven fabric. Materials include polyester, polyolefin, vinylon, aramid, carbon fiber, and glass fiber, with polypropylene nonwoven fabric or glass nonwoven fabric being 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 10 can be firmly attached to the concrete structure. Suitable glass nonwoven fabrics include chopped strand mat, glass paper, and felt.

[0051] When a polypropylene nonwoven fabric is used, it is preferable to subject the fiber surface to a surface treatment in order to increase compatibility with the curable composition.

[0052] 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. When the thickness of the third layer 3 is 0.1 mm or more, the adhesive strength between the repair material 10 and the concrete structure is ensured, and when the thickness is 1.5 mm or less, the amount of the hardenable composition impregnated into the laminates 4, 4' can be reduced, which is economically advantageous.

[0053] In the laminate 4, for example, a glass nonwoven fabric can be used as the third layer 3, a triaxial vinylon mesh can be used as the first layer 1, and a polypropylene spunbond nonwoven fabric can be used as the second layer 2.

[0054] (integrated lamination) The repair material 10, 10', which is composed of at least two laminated sheet-like members, may be integrated by impregnating them with a curable composition, but it is preferable to integrate them in advance, which prevents the sheet members from shifting during application and impregnation.

[0055] The integration method may utilize mechanical fiber entanglement, chemical adhesion, etc., and examples thereof include fulling, needle punching, chemical bonding, thermal bonding, and hydroentanglement.

[0056] While Fig. 1 shows a three-layer structure of the repair material 10, the repair material may have four or more layers. Even in the case of four or more layers, it is preferable that the second layer 2 be disposed on the outer side of the first layer 1, counting from the side that contacts the concrete structure 100. This layered structure allows the repair material 10 to have both strength and adhesion to the concrete structure. There is no particular limit to the maximum number of layers in the laminate 4.

[0057] (Curable composition) The hardenable composition (one example of a composition) is applied to and / or impregnated into the laminate 4, 4'. By applying and / or impregnating the laminate 4, 4' with the hardenable composition and then hardening the hardenable composition, the concrete structure 100 and the repair material 10, 10' can be bonded together. For example, the hardenable composition can be in a liquid form. By bonding the repair material 10, 10', it is possible to prevent concrete pieces from peeling off from the deteriorated portion of the concrete structure 100.

[0058] The hardenable composition contains an aqueous silicate solution (an example of a second aqueous silicate solution) and a Hozolan active substance. The aqueous silicate solution is, for example, an aqueous solution of sodium silicate, potassium silicate, lithium silicate, or a mixture thereof. A composition containing an aqueous silicate solution and a Hozolan active substance in this manner may be referred to as a "geopolymer" hereinafter. The hardenable composition is usually prepared as a liquid composition.

[0059] In this way, by using an inorganic material in the hardenable composition, the fire resistance of the concrete structure 100 can be ensured without being impaired.

[0060] In geopolymers, the difference in specific gravity between the liquid component consisting of the silicate aqueous solution and the solid component consisting of the pozzolanic active substance is smaller than the difference in specific gravity between the water and cement contained in the cement slurry, so separation of the components in the hardenable composition can be suppressed.

[0061] In addition, when sodium silicate and potassium silicate are applied to and / or impregnated into the surface 100s of the concrete structure 100, they can produce a CSH gel with calcium hydroxide in the concrete, thereby strengthening the adhesive strength between the repair material 10, 10' and the concrete structure 100.

[0062] Such a curable composition preferably has a viscosity of 400 mPa·s or more and 3000 mPa·s or less at 25° C. By adjusting the viscosity to such a level, it is possible to ensure the impregnation into the laminates 4, 4′. It is also possible to prevent the curable composition from dripping when applied to the concrete structure 100.

[0063] In particular, when using geopolymers, 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, 0 mS / cm or more, or 7 mS / cm or more, and even more preferably 0.8 mS / cm or more, 1.0 mS / cm or more, or 1.2 mS / cm or more.

[0064] Such a difference in electrical conductivity ensures sufficient reactivity with the silicate solution and enhances the adhesive strength between the repair material 10, 10' and the concrete structure 100. The electrical conductivity difference here is an index 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 solution before and after the addition of the pozzolanic active substance. The electrical conductivity difference is calculated as follows: Following the method described in "Cement Concrete Research, Vol. 19, pp. 63-68, 1989," the electrical conductivity of 200 ml of saturated Ca(OH)2 solution is measured at 40±1°C. Next, 5 g of metakaolin is added, stirred, and the electrical conductivity is measured two minutes later. The difference from the electrical conductivity before the addition is defined as the electrical conductivity difference.

[0065] A pozzolanic active substance is a substance that hardens when water reacts with calcium oxide, calcium hydroxide, aluminum hydroxide, etc. Examples of pozzolanic active substances include silica dust, diatomaceous earth, talc, aerosil, white carbon, kaolin, metakaolin, activated clay, and acid clay. Of these, metakaolin is preferred.

[0066] It is generally preferred that the pozzolan active substance have a silica content of 40% by weight or more when the silica component is converted into SiO2, or an alumina content of 30% by weight or more when the alumina component is converted into Al2O3.

[0067] The pozzolanic active substance is usually in a lump or powder form, and may be used as is in a lump or powder form. Alternatively, the pozzolanic active substance may be activated by a method such as thermal spraying, pulverization / classification, or application of mechanical energy, after which the state of the substance is changed.

[0068] The thermal spraying method is a thermal spraying technique used for ceramic coating. Examples of the thermal spraying technique include plasma thermal spraying, high-energy gas thermal spraying, and arc thermal spraying. Preferably, the material powder is melted at a temperature of 2000°C or higher and 16000°C or lower, sprayed at a speed of 30 m / s or higher and 800 m / s or lower, and sprayed to a surface having a specific surface area of ​​0.1 m. 2 / g or more, 100m 2 It is preferable to make the powder to have a density of 1 / g or less.

[0069] Any known method can be used for the pulverization and classification. Pulverization can be performed using a jet mill, a roll mill, a ball mill, or the like. Classification can be performed using a sieve, specific gravity, wind force, wet sedimentation, or the like. These methods can be used in combination as desired.

[0070] Examples of methods for applying mechanical energy include methods using a ball media mill, a media agitation mill, a roller mill, etc. The applied mechanical energy is preferably 0.5 kWh / kg or more and 30 kWh / kg or less in order to minimize the load while providing adequate activation.

[0071] The total content of sodium, potassium, lithium, or mixtures thereof derived from the silicate solution in the curable composition, e.g., geopolymer, calculated as M2O (M is sodium, potassium, and lithium) is preferably 5 to 30 wt.%, more preferably 10 to 30 wt.%, based on the dry solids content of the cured product. The content of aluminum derived from the pozzolanic active substance, calculated as Al2O3, is preferably 20 to 40 wt.%, more preferably 25 to 35 wt.%, based on the dry solids content of the cured product.

[0072] Furthermore, the curable composition is preferably one in which the molar ratio of an aqueous solution of sodium silicate, potassium silicate, lithium silicate, or a mixture thereof, represented by the following formula (2), is 0.8 or more and 2.2 or less, more preferably 1.0 or more and 2.2 or less, and even more preferably 1.0 or more and 2.0 or less.

[0073] Molar ratio = SiO2 / M2O (2) The molar ratio represents the ratio of SiO to MO (SiO / MO) derived from the aqueous silicate solution (M is an alkali metal containing at least one selected from sodium, potassium, and lithium), and is a number related to the reactivity with the pozzolanic active substance. The molar ratio of the aqueous silicate solution used in the hardenable composition is equal to or greater than the molar ratio of the aqueous silicate solution used as a primer, as described below.

[0074] (Other Components of the Curable Composition) In addition to the above components, the curable composition may contain additives known in the art. Examples include fillers, modifiers, dispersants, curing time adjusters, pigments, antioxidants, polymer emulsions, etc. These are not particularly limited, and known additives can be used. The filler may be any of those commonly used as a filling agent.

[0075] Examples include carbon, cellulose, mineral fine powder, synthesized inorganic crystalline powder, etc. Modifiers include various metal salts that can react with silicate aqueous solutions, such as light-burned magnesium oxide and zinc oxide. Polymer emulsions include acrylic rubber, styrene-butadiene rubber, and mixtures thereof.

[0076] These additives can be used in any amount as long as the intended function of the curable composition is not impaired. In particular, the polymer emulsion is preferably blended so that the polymer solids weight is 3 wt% or more and 10 wt% or less 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.

[0077] The amount of the curable composition impregnated into the laminates 4, 4' is not particularly limited, and is preferably adjusted so that the curable composition is uniformly held throughout the laminates 4, 4' and the entire laminates 4, 4' can be firmly integrated by curing the curable composition. For example, the weight ratio of laminate to curable composition is preferably about 1:4 to 1:12, and more preferably 1:4 to 1:10.

[0078] For example, a geopolymer containing silicate solution, latex, metakaryon, and blast furnace slag can be used as the curable composition. In this case, when the laminate 4 uses a glass nonwoven fabric as the third layer 3, a triaxial vinylon mesh as the first layer 1, and a polypropylene spunbond nonwoven fabric as the second layer 2, the curing time can be set to, for example, 7 days or more at 23°C and 50% RH.

[0079] (Impregnated material layer 5) The impregnating material layer 5 is formed by applying the following primer to the concrete structure 100 and then impregnating it.

[0080] The impregnating material layer 5 is coated with a composition containing a silicate aqueous solution (an example of a first silicate aqueous solution) as a primer, and then dried as necessary. When the composition containing the silicate aqueous solution is dried, it may be in a state where it is dry to the touch. "Dry to the touch" refers to a dry state where the solution or composition does not stick to the finger even when lightly touched with the finger.

[0081] Examples of silicate aqueous solutions used as primers include aqueous solutions of sodium silicate, potassium silicate, lithium silicate, or mixtures thereof. Sodium silicate and potassium silicate can form a CSH gel with calcium in the solution applied to the surface of the concrete structure 100, thereby strengthening the adhesive strength between the repair material 10, 10' and the concrete structure 100.

[0082] The silicate aqueous solution used as a primer preferably has a molar ratio of sodium silicate, potassium silicate, lithium silicate, or a mixture thereof of 0.5 or more and 1.8 or less, more preferably 1.6 or less. The molar ratio of the silicate aqueous solution used as a primer is expressed by the above formula (2), similar to the silicate aqueous solution used in the curable composition. The molar ratio of the silicate aqueous solution used as a primer is smaller than the molar ratio of the silicate aqueous solution used in the curable composition.

[0083] Furthermore, the solid content ratio of the silicate aqueous solution is preferably 20% by weight or more and 50% by weight or less, as the total weight of SiO2 and MO derived from Si and M contained in the silicate aqueous solution, and when the silicate aqueous solution is sodium silicate, it is more preferably 20% by weight or more and 30% by weight or less, from the viewpoint of storage stability of the aqueous solution.

[0084] By setting the solid content ratio in this range, gaps occurring in the deteriorated concrete can be efficiently filled, and the strength of the deteriorated concrete can be increased.

[0085] For example, a silicate aqueous solution (SiO2 / Na2O: molar ratio 1.6, solid content 27% by weight) was added at 100 g / m 2 More than 200g / m 2 The following application amounts can be applied. In this case, the paint will be dry to the touch in approximately 180 minutes, depending on the outside temperature and humidity.

[0086] It is preferable to perform a scraping treatment on the surface 100s of the concrete structure 100 before applying the composition containing the silicate aqueous solution to the surface 100s.

[0087] <Methods for repairing concrete structures> The concrete structure repair method of the present disclosure can be carried out using the concrete structure repair materials 10, 10' described above.

[0088] FIG. 3 is a flow diagram showing the concrete structure repair method of the present disclosure.

[0089] As shown in FIG. 3, the concrete structure repair method of the present disclosure includes step S10 (scraping step), step S20 (application step), step S30 (affixing step), and step S40 (hardening step).

[0090] (Step S10 (cleaning process)) In step S10, the surface 100s of the concrete structure 100 to be repaired is scraped with a grinder equipped with a concrete grinding blade.

[0091] (Step S20 (coating process)) In step S10, a composition containing an aqueous silicate solution is applied to the surface 100s of the concrete structure 100 that has been subjected to the scraping treatment, and is allowed to permeate the surface 100s of the concrete structure 100.

[0092] Methods for applying and impregnating the composition containing the silicate aqueous solution to the concrete structure 100 include, for example, a hand layup method in which application and impregnation are performed manually using a roller, or a method in which application and impregnation are performed by spraying.

[0093] (Step S30 (sticking process)) In step S30, repair materials 10, 10' are applied to the surface 100s of the concrete structure 100 to which the composition containing the silicate aqueous solution has been applied.

[0094] In the pasting step, a curable composition is applied to the laminates 4, 4', and the laminates 4, 4' are impregnated with the curable composition. For example, after applying the curable composition to the surface 100s of the concrete structure 100 to which a composition containing an aqueous silicate solution has been applied, the laminates 4, 4' may be pasted, and the curable composition may be applied from above the pasted laminates 4, 4' to paste the repair materials 10, 10'.

[0095] The laminates 4, 4' may be formed and then impregnated with the curable composition, or the laminates 4, 4' may be formed after impregnation with the curable composition, or the laminates 4, 4' may be formed and then impregnated with the curable composition while being impregnated. Furthermore, the laminates 4, 4' may be impregnated with the curable composition either before or after being attached to the target concrete structure.

[0096] Examples of methods for impregnating the laminates 4, 4′ with the curable composition include (1) a hand layup method in which coating and impregnation are performed manually using a roller, (2) a method of coating and impregnation by spraying, (3) a method in which the thickness of the laminates 4, 4′ is defined using a mold and then the curable composition is coated and impregnated into the laminates 4, 4′ by press-fitting, (4) a method in which the thickness of the laminates 4, 4′ is defined by reducing pressure and then the curable composition is impregnated into the laminates 4, 4′ by reduced pressure injection, (5) a method in which the laminates 4, 4′ are immersed in the curable composition, the laminates 4, 4′ are continuously impregnated with the curable composition, and then the thickness of the laminates 4, 4′ is defined by a roll, and (6) a method in which continuous coating and impregnation are performed by roll transfer. These methods may also be used in combination.

[0097] To improve workability during impregnation and to prevent the impregnated sheets from adhering to each other and to prevent dust from adhering to the impregnated sheets, the front and back surfaces of the laminates 4, 4' may be covered with a resin protective film. This protective film is removed when the laminates are attached to the concrete structure.

[0098] The obtained repair material 10, 10' is applied to the surface 100s of a concrete structure 100 that has been coated with and dried using a composition containing an aqueous silicate solution. At this time, it is important to remove any air bubbles that have entered between the repair material 10, 10' and the surface of the concrete structure 100, particularly in order to improve adhesion between the repair material 10, 10' and the surface 100s of the concrete structure 100. A suitable method for removing air bubbles is to use a roll, metal spatula, or the like to expel the air bubbles to the outside of the repair material 10, 10'.

[0099] (Step S40 (hardening process)) The hardenable composition impregnated into the laminates 4, 4' is hardened by placing the repair materials 10, 10' in close contact with the concrete structure 100. From the viewpoint of ensuring time for the hardenable composition to be impregnated into the surface 100s of the concrete structure 100, the hardening time of the hardenable composition is preferably 30 minutes or more and 300 minutes or less, and more preferably 45 minutes or more and 240 minutes or less.

[0100] Because the curable composition of the present disclosure is an inorganic material, the curing time can be adjusted by the amount of water contained. When the curable composition is a geopolymer, the curing time can be adjusted by the content of sodium, potassium, lithium, or a mixture thereof derived from the silicate aqueous solution, the ratio (SiO / MO) of SiO to MO (where M is sodium, potassium, or lithium) derived from the silicate aqueous solution, the difference in electrical conductivity of the pozzolan active substance, the aluminum content, etc.

[0101] When the hardening of the hardenable composition is complete, the repair materials 10, 10' are fixed to the concrete structure 100, and the repair of the concrete structure 100 can be completed. [Example]

[0102] The concrete structure repair method of the present disclosure will be described below using examples.

[0103] Example 1 The concrete substrate was a top-lid type U-shaped gutter cover (Type 1, nominal size 150) specified in JIS A 5372.

[0104] In step S10, the surface of this concrete was scraped with a grinder equipped with a concrete grinding blade.

[0105] Next, a silicate aqueous solution was prepared by adding 100 g of a JIS K 1408 No. 3 sodium silicate aqueous solution, 25 g of a 48 wt % sodium hydroxide aqueous solution, and 53 g of water, and the mixture was stirred for 24 hours to obtain a silicate aqueous solution with a molar ratio of 1.6 and a solid content of 27 wt %.

[0106] Next, in step S20, the silicate aqueous solution is applied to the surface of the concrete using a roller in an amount of 150 g / m 2 The concrete surface was then left to dry at room temperature for 180 minutes, and the surface was then primed. The primed portion corresponds to the impregnating material layer 5.

[0107] Next, 56 g of a JIS K 1408 No. 3 sodium silicate aqueous solution, 14 g of a 48 wt % sodium hydroxide aqueous solution, 30 g of water, and 10 g of latex (product name: SR-151, manufactured by Nippon A&L Co., Ltd.) were stirred for 24 hours to obtain a silicate aqueous solution with a molar ratio of 1.6 and a solids content of 27 wt %. 77 g of metakaolin (manufactured by BASF, product name: SP-33, electrical conductivity difference 0.8 mS / cm) as a pozzolanic active substance and 44 g of blast furnace slag powder (manufactured by Nippon Steel & Sumikin Cement Co., Ltd., product name: Esment) as specified in JIS A 6206 were mixed with the above aqueous solution to prepare a curable composition.

[0108] Next, glass nonwoven fabric (weight 25g / m 2 , thickness 0.2 mm, porosity 95%), triaxial mesh sheet (basis weight 90 g / m) made of vinylon multifilament 2 , mesh size 8 mm, thickness 0.35 mm, X=3.0) and hydrophilic polypropylene spunbond nonwoven fabric (weight 30 g / m 2A laminate was prepared by laminating two sheets of paper (0.2 mm thick, tear strength 16 N).

[0109] The glass nonwoven fabric corresponds to the "third layer," and the triaxial mesh sheet corresponds to the "first layer," with a basis weight of 30 g / m. 2 The spunbond nonwoven fabric corresponds to the "first layer."

[0110] Next, in step S30, the sheet-like laminate prepared above, measuring 300 mm x 300 mm, was impregnated with 100 g of a curable composition, and a repair material was applied to the surface of the impregnating material layer 5, which was the surface treatment portion.

[0111] Next, in step S40, the curable composition impregnated into the laminate attached to the surface 100s of the concrete structure 100 was cured to prepare a repair material for the concrete structure.

[0112] The entire procedure was carried out in an environment of 23°C and 50% RH.

[0113] Example 2 A silicate aqueous solution was prepared by adding 100 g of a potassium silicate aqueous solution (manufactured by Fujifilm Wako Pure Chemical Industries, product name: potassium silicate solution (approximately 50%), molar ratio: 2.0, solid content: 50 wt%) and 25 g of a 48 wt% potassium hydroxide aqueous solution, and the mixture was stirred for 24 hours to obtain a silicate aqueous solution with a molar ratio of 1.4 and a solid content of 48 wt%.

[0114] Next, in this Example 2, unlike Example 1, this silicate aqueous solution was used in the above step S20. Except for this, a repair material for a concrete structure was prepared in the same manner as in Example 1.

[0115] (Comparative Example 1) A concrete structure repair material was prepared in the same manner as in Example 1, except that in step S20 above, a No. 3 sodium silicate aqueous solution (molar ratio: 3.0, solid content: 39% by weight) specified in JIS K 1408 was used as the silicate aqueous solution.

[0116] (Comparative Example 2) In step S20, a concrete structure repair material was prepared in the same manner as in Example 1, except that a potassium silicate aqueous solution (manufactured by Fujifilm Wako Pure Chemical Industries, trade name: potassium silicate solution (approximately 50%), molar ratio: 2.0, solid content: 50% by weight) diluted twice with water was used as the silicate aqueous solution.

[0117] (Comparative Example 3) A concrete structure repair material was prepared in the same manner as in Example 1, except that in step S20 above, a colloidal silica aqueous solution (manufactured by Nissan Chemical Industries, Ltd., trade name: ST-40, molar ratio: ∞, solid content: 40 wt%) was used instead of the silicate aqueous solution.

[0118] (Adhesion strength evaluation) The adhesive strength of the concrete structure repair materials of each Example and Comparative Example to concrete was evaluated using a simple tensile tester (Technotester R-10000ND) manufactured by the Construction Research Institute. Specifically, concrete to which the repair materials prepared in each Example and Comparative Example had been applied was cured for 7 days, and then immersed in tap water for 3 days. After being removed, the concrete was dried for 7 days, and the adhesive strength was measured according to the standard method of use of the simple tensile tester. The entire series of operations was carried out in an environment of 23°C and 50% RH. The simple tensile test was performed on three specimens for each example and comparative example, and the average was taken as the adhesive strength. The results are shown in Table 1. The row for step S20 in Table 1 shows the type and molar ratio of the silicate aqueous solution in the above-mentioned examples 1 and 2 and comparative examples 1 to 3.

[0119] For example, the adhesive strength is 1.0 N / mm 2 Above 1.0N / mm is considered good. 2 If it is smaller than

[0120] [Table 1]

[0121] As described above, the results of the adhesive strength evaluation of the repair materials in the examples confirmed that the concrete repair material of the present disclosure can significantly improve the reinforcing performance and adhesion performance of deteriorated concrete. [Explanation of symbols]

[0122] 1 First layer 2 Second layer 3 Third layer 4, 4´ laminate 10, 10´ Repair materials 100 Concrete Structures 100s surface

Claims

1. an application step of applying a composition containing a first silicate aqueous solution to a surface of concrete to be repaired; a bonding step of bonding a repair material obtained by coating or impregnating a laminate with a composition containing a second silicate aqueous solution and a pozzolan active substance onto the surface of the concrete after the coating step; a curing step of curing the repair material after the attaching step, The molar ratio of the first silicate aqueous solution and the molar ratio of the second silicate aqueous solution are M ２ SiO to O ２ Molar ratio (SiO ２ / M ２ 0), wherein M is at least one alkali metal selected from lithium, sodium, and potassium; The molar ratio of the second silicate aqueous solution is equal to or greater than the molar ratio of the first silicate aqueous solution; Methods for repairing concrete structures.

2. The molar ratio of the first silicate aqueous solution is 0.5 or more and 1.8 or less, The molar ratio of the second silicate aqueous solution is 0.8 or more and 2.2 or less; The method for repairing a concrete structure according to claim 1.

3. The laminate is a sheet-like first layer formed by combining multifilaments in a multiaxial mesh shape; a sheet-like second layer formed from a polypropylene spunbond nonwoven fabric; The first layer and the second layer are arranged in this order from the surface side of the concrete.

3. The method for repairing a concrete structure according to claim 1 or 2.

4. The laminate further includes a sheet-like third layer formed of a glass nonwoven fabric and arranged on the surface side of the concrete of the first layer. The method for repairing a concrete structure according to claim 3.

5. The method further includes a scraping step of scraping the surface of the concrete before the application step. The method for repairing a concrete structure according to any one of claims 1 to 4.

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