Repair method and repair mortar composition for deteriorated parts of existing structures

Abstract

To provide a repairing method for a deteriorated part of an existing structure having long-term durability by reinforcing an interface between concrete and cement mortar by spraying a repairing mortar composition containing a specific material and satisfying results of adhesion strength, a thick coating property test, a setting time test and chloride ion penetration depth measured by a specific method to a place where the deteriorated part is removed in the existing structure, which is a concrete structure.SOLUTION: A repairing method for deteriorated parts of existing structures comprises the steps of: removing a deteriorated part in an existing structure; and spraying a repairing mortar composition on a part where the deteriorated part has been removed, wherein the repairing mortar composition contains cement, fine aggregate, a salt fixing material mainly composed of CaO 2Al2O3, a water-reducing agent, fibers, a polymer for cement admixture, a quick-hardening material, and water, and the repairing mortar composition satisfies the results of an adhesion test, a thick coating property test, a setting time test, and a chloride ion penetration depth test.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a repair method and a repair mortar composition for deteriorated parts of existing concrete structures. [Background technology]

[0002] Concrete structures such as tunnels and bridges are susceptible to deterioration due to factors such as salt damage, carbonation, freeze-thaw cycles, and chemical corrosion, which can lead to cracks and delamination on the surface. As a countermeasure, a cross-section repair method is widely implemented, in which deteriorated areas are identified and removed using methods such as impact testing, and then repaired by filling them with repair materials. In such cross-sectional repair methods, when the repair cross-sectional area is large, it is common to use a mechanized system and employ methods such as filling the area with a highly fluid material or spraying cement mortar.

[0003] Traditionally, cement mortar has been primarily used for surface finishing and cross-sectional repair of concrete structures. Cement mortar is usually manufactured by agitating and mixing cement, aggregate, and water in a mortar mixer. The application method for cement mortar often involves applying the repair mortar composition with a trowel, but this method requires skill, and applying a thickness of 10 mm or more to ceiling surfaces is difficult, resulting in considerable labor. Therefore, a method of pumping and spraying the repair mortar composition has been proposed (see, for example, Patent Documents 1-4). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 09-012379 [Patent Document 2] Japanese Patent Application Publication No. 09-296453 [Patent Document 3] Japanese Patent Application Publication No. 10-216628 [Patent Document 4] Patent No. 4785359

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in tunnels, bridges, and other concrete structures, there is water accumulation and leakage due to groundwater, rainfall, etc. This water affects the interface between the concrete, which is a vulnerable part, and the cement mortar, and there is a risk that the adhesion performance between the concrete and the cement mortar will deteriorate. Furthermore, when the water contains salts, there is also a risk that the cement mortar will crack due to steel corrosion. Therefore, there is a problem of strengthening the interface between the concrete and the cement mortar and improving the salt resistance in order to have long-term durability. Also, from the perspective of obtaining long-term durability, it can be said that it is preferable to further have water impermeability. There is a problem of improving the water impermeability and salt resistance in order to have long-term durability.

[0006] The present invention provides a repair method and a repair mortar composition for a deteriorated part of an existing structure having long-term durability by spraying a repair mortar composition containing a specific material onto a location where the deteriorated part of the concrete in the existing structure has been removed, satisfying the results of the adhesion strength, thick coating property test, setting time test, and chloride ion penetration depth measured by a specific method, thereby strengthening the interface between the concrete and the cement mortar.

Means for Solving the Problems

[0007] As a result of intensive research to solve the above problems, the inventors of the present invention have found that by spraying a specific repair mortar composition onto a location where the deteriorated part of an existing structure has been removed, the interface between the concrete and the cement mortar can be strengthened and it has long-term durability, thus completing the present invention. That is, the present invention is as follows. [1] It includes a step of removing the concrete deteriorated part in the existing structure and a step of spraying a repair mortar composition onto the location where the deteriorated part has been removed. The repair mortar composition contains cement, a salt-fixing material mainly composed of CaO·2Al2O3, fine aggregate, water reducer, fiber, a polymer for cement admixture, a quick-setting material, and water. The repair mortar composition is a repair method for deteriorated parts of existing structures that meets the results of the following adhesion test, thick coating property test, setting time test, and chloride ion penetration depth test. 〔Adhesion test〕 The repair mortar composition is sprayed onto the upper surface of a concrete rectangular parallelepiped with a square bottom and top of 300 mm × 300 mm and a height of 60 mm until the height reaches 60 mm, and a temporary test piece in the shape of a rectangular parallelepiped with a square bottom and top of 300 mm × 300 mm and a height of 120 mm is prepared. The adhesion strength at 28 days of age is 1.3 N / mm 2 or more. 〔Thick coating property test〕 A wooden frame with an opening of 60 mm in diameter is installed on the upper surface of a mortar plate in the shape of a rectangular parallelepiped with a square bottom and top of 70 mm × 70 mm and a height of 20 mm. The repair mortar composition is sprayed until the height reaches 60 mm to prepare a test piece. The adhesion strength at 24 hours of age is 1.0 N / mm 2 or more. 〔Setting time test〕 The repair mortar composition is sprayed to prepare a test piece with dimensions of 100 mm × 100 mm × 100 mm. The time when the penetration resistance value reaches 3.5 N / mm 2 is 10 minutes or more and within 1 hour. 〔Chloride ion penetration depth test〕 A preliminary test specimen is prepared in the shape of a rectangular prism with a height of 120 mm, by spraying the repair mortar composition onto the top surface of a rectangular prism concrete with a bottom and top surface of 300 mm x 300 mm and a height of 60 mm until it reaches a height of 60 mm. A cubic test specimen is prepared by cutting the prepared preliminary test specimen to 120 mm (length) x 120 mm (width) x 120 mm (height) such that the portion consisting of the concrete and the repair mortar composition has the same volume in the height direction. The prepared cubic test specimen is immersed in seawater with a salinity of 3.5%, and after 28 days, the chloride ion penetration depth of the portion of the cubic test specimen consisting of the repair mortar composition is 35% or less compared to the chloride ion penetration depth of the portion consisting of the concrete of the cubic test specimen. [2] The repair mortar composition has a permeability coefficient of 200 × 10⁻¹⁰ obtained by the following permeability coefficient test. -10 A repair method for deteriorated parts of existing structures as described in [1], which is less than cm / sec. [Hydroelectric coefficient test] A preliminary test specimen is prepared in the shape of a rectangular prism with a bottom and top surface of 300 mm x 300 mm and a height of 120 mm. The preliminary test specimen is then cut into two sections of concrete and repair mortar composition, each section having the same volume in the height direction. The cylindrical test specimen is then prepared by cutting a section of concrete and repair mortar composition with a diameter of 100 mm and a height of 150 mm. The permeability coefficient of the cylindrical test specimen is then measured. [3] The repair method for deteriorated parts of existing structures according to [1] or [2], wherein in the step of spraying the repair mortar composition, the spraying speed of the repair mortar composition is 5 to 25 L / min. [4] A repair method for deteriorated parts of an existing structure according to any one of [1] to [3], wherein in the step of spraying the repair mortar composition, the pressure applied to the pump that pumps the repair mortar composition is 2 MPa or less. A repair mortar composition for use in a repair method for deteriorated parts of existing structures as described in any of [5][1] to [4], comprising: a repair mortar material comprising 100 parts by mass of cement, 4 to 10 parts by mass of a salt fixing agent mainly composed of CaO·2Al2O3, 160 to 190 parts by mass of fine aggregate, 0.01 to 1.00 parts by mass of a water-reducing agent, 1.4 to 1.8 parts by mass of fiber, 4 to 12 parts by mass of a polymer for cement admixture, and 6 to 12 parts by mass of a rapid-hardening agent; and 11 to 17 parts by mass of water per 100 parts by mass of the repair mortar material. [Effects of the Invention]

[0008] According to the present invention, a repair method and repair mortar composition for repairing deteriorated parts of existing concrete structures can be provided, which strengthens the interface between concrete and cement mortar and provides long-term durability, by spraying a repair mortar composition containing specific materials and satisfying the results of a setting time test, adhesion strength, thickness test, and chloride ion penetration depth, all measured by a specific method, onto the area where the deteriorated part of the existing concrete structure has been removed. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic perspective view showing the preparation of a preliminary test specimen to obtain test specimens for chloride ion penetration depth tests and hydraulic conductivity tests. [Figure 2] This is a schematic perspective view showing the preparation of a test specimen for chloride ion penetration depth testing. [Figure 3] These are schematic perspective and cross-sectional views illustrating the preparation of test specimens for the thick coating test. [Figure 4] This is a schematic perspective view showing the preparation of a test specimen for a permeability coefficient test. [Modes for carrying out the invention]

[0010] The present invention will be described in detail below. In this invention, parts and percentages are expressed on a mass basis unless otherwise specified.

[0011] A repair method for deteriorated parts of existing structures according to an embodiment of the present invention includes the steps of removing the deteriorated parts of the existing structure and spraying a repair mortar composition onto the areas from which the deteriorated parts have been removed.

[0012] The process of removing deteriorated parts from existing structures involves removing areas where cracks or delamination have occurred on the surface due to deterioration caused by factors such as salt damage, carbonation, freeze-thaw cycles, and chemical corrosion, as well as deterioration due to aging. Methods for removing deteriorated parts include, for example, identifying the deteriorated area through impact testing and then removing it using electric picks, air picks, jet chisels, and water jets.

[0013] In the repair method, the step of spraying the repair mortar composition involves using a pressure pump to pump the prepared repair mortar composition through a mortar pressure pipe to a mixing pipe, mixing it with compressed air in the mixing pipe, and then spraying it from a nozzle.

[0014] In the process of spraying the repair mortar composition, the spraying speed of the repair mortar composition is preferably 5 to 25 L / min, and more preferably 10 to 20 L / min. If the spraying speed of the repair mortar composition is below the lower limit, the construction time will be long, the work efficiency will be poor, and the repair will be uneven. On the other hand, if the spraying speed of the repair mortar composition exceeds the upper limit, pressure will be applied instantaneously, resulting in an uneven repair.

[0015] In the process of spraying the repair mortar composition, the pressure of the pump used to deliver the repair mortar composition is preferably 2 MPa or less, and more preferably 1.5 MPa or less. Furthermore, the pressure of the pump used to deliver the repair mortar composition is preferably 0.1 MPa or more, and more preferably 0.3 MPa or more. By keeping the pressure of the pump below the above upper limit or above the above lower limit, the repair mortar composition can be sprayed uniformly, resulting in a uniform repair.

[0016] Chemical hoses, pressure-resistant hoses with metal mesh, and metal pipes can be used as mortar pumping pipes for pumping the repair mortar composition. Typically, chemical hoses or pressure-resistant hoses are used, and it is preferable to use metal pipes before and after them. The length of the mortar pumping pipe is not particularly limited, and the length used will vary depending on the construction situation, but typically, pipes of 5 to 30 meters are used. Mortar pumping pipes typically have a diameter of 1 to 2 inches, considering factors such as pumping performance and ease of handling of pressure-resistant hoses.

[0017] The pump used to pump the repair mortar composition is not particularly limited, but any chemical pump that pumps an aqueous solution at a constant pressure without backflow, such as a plunger pump, squeeze pump, or snake pump, can be used.

[0018] The mixing pipe connecting the mortar pumping pipe and the nozzle mixes the mixed mortar with compressed air, and a shower pipe is typically used.

[0019] The nozzle used in this invention is connected to the mixing pipe at the tip of the mortar pumping pipe and can be a nozzle that continuously reduces in diameter, or a nozzle that has a straight pipe attached to straighten the flow of a fast-setting repair mortar composition after the diameter has been reduced. The nozzle length is preferably 15 to 145 cm, and more preferably 25 to 75 cm, from the viewpoint of adhesion, dust reduction, and pressure feeding. Nozzles can be made of metal or ceramic, or they can be made of rubber with ceramic or metal lining on the inner surface of the tubing, or with tips of these materials embedded inside.

[0020] The repair mortar composition of the present invention contains cement, a salt fixative mainly composed of CaO·2Al2O3, fine aggregate, a water-reducing agent, fibers, a polymer for cement admixture, a hardening agent, and water.

[0021] The cement used in the present invention is not particularly limited, and various cements such as ordinary, early-strength, super-early-strength, low-heat and medium-heat cements, various blended cements obtained by mixing blast furnace slag, fly ash, silica fume, etc. with these cements, environmentally friendly cements (eco-cements) manufactured using municipal waste incineration ash or sewage sludge incineration ash as raw materials, commercially available fine particle cements, etc. may be mentioned, and it is also possible to use various cements and various blended cements after being pulverized into fine powder. In addition, those adjusted by increasing or decreasing the amount of components (for example, gypsum, etc.) usually used in cement can also be used. In the present invention, it is preferable to select ordinary Portland cement or early-strength Portland cement from the viewpoints of high fluidity, carbonation resistance, adhesion strength, and rust prevention.

[0022] From the viewpoints of manufacturing cost and strength development property, the Blaine specific surface area value (hereinafter, also referred to as Blaine value) of the cement used in the present invention is preferably 2,500 cm 2 / g or more and 7,000 cm 2 / g or less, more preferably 2,750 cm 2 / g or more and 6,000 cm 2 / g or less, and even more preferably 3,{000} cm 2 / g or more and 4,500 cm 2 / g or less. The Blaine specific surface area value is determined in accordance with JIS R 5201 (Physical test methods for cement).

[0023] The salt immobilization material used in this invention is a calcium aluminate compound (hereinafter referred to as CA compound) mainly composed of CaO·2Al2O3, obtained by mixing raw materials containing calcia and raw materials containing alumina, etc., and performing heat treatment such as firing in a kiln or melting in an electric furnace. In this invention, the composition is in the range of 0.15 to 0.7 in terms of CaO / Al2O3 molar ratio. Even if the CA compound contains, for example, SiO2 or R2O (where R is an alkali metal), it can be used as long as it does not impair the purpose of this invention. The CaO / Al2O3 molar ratio of the CA compound is 0.15 to 0.7, with 0.4 to 0.6 being preferred. By having a CaO / Al2O3 molar ratio of the CA compound above the lower limit, a sufficient shielding effect against chloride ions can be obtained. Furthermore, by having a CaO / Al2O3 molar ratio of the CA compound below the upper limit, it is possible to ensure an appropriate pot life.

[0024] One method for obtaining a calcium aluminate compound as a salt fixation agent, mainly composed of CaO·2Al2O3, is to heat-treat CaO raw materials and Al2O3 raw materials using a rotary kiln or electric furnace. Examples of CaO raw materials used in the production of calcium aluminate compounds, which are salt fixatives with CaO·2Al2O3 as the main component, include calcium carbonate such as limestone and seashells, calcium hydroxide such as slaked lime, or calcium oxide such as quicklime. Furthermore, examples of Al2O3 raw materials include bauxite and industrial by-products such as aluminum residue ash.

[0025] When calcium aluminate compounds are obtained industrially, they may contain impurities. Specific examples include SiO2, Fe2O3, MgO, TiO2, MnO, Na2O, K2O, Li2O, S, P2O5, and F. However, the presence of these impurities is not particularly problematic as long as it does not substantially hinder the objectives of the present invention. Specifically, it is not particularly problematic if the total amount of these impurities is 10% or less.

[0026] The particle size of the calcium aluminate compound, which is mainly composed of CaO·2Al2O3 and serves as a salt fixation agent in this invention, is not particularly limited, but is typically 2,000 to 7,000 cm² in Blaine value. 2 A value of / g is preferred, and the range is 3,000 to 6,000 cm². 2 / g is more preferable. By having the particle size of the calcium aluminate compound, which is a salt fixation material mainly composed of CaO·2Al2O3, within the above range, it is possible to obtain a sufficient shielding effect against chloride ions and ensure an appropriate pot life.

[0027] The mixing ratio of the salt fixative mainly composed of CaO·2Al2O3 is preferably 1 to 35 parts by mass, more preferably 2 to 20 parts by mass, and even more preferably 4 to 10 parts by mass, per 100 parts by mass of cement. If the mixing ratio of the salt fixative mainly composed of CaO·2Al2O3 is less than 1 part by mass, the salt-blocking properties cannot be sufficiently exhibited. Also, if the mixing ratio of the salt fixative mainly composed of CaO·2Al2O3 exceeds 35 parts by mass, the fluidity will be impaired. By mixing the salt fixative mainly composed of CaO·2Al2O3 in a ratio of 1 to 35 parts by mass, a repair mortar composition with excellent salt resistance can be obtained.

[0028] The fine aggregate used in this invention reduces drying shrinkage and improves durability. There are no particular limitations on the type of fine aggregate, but they can be classified into categories such as silica sand, limestone, blast furnace granulated slag, and recycled aggregate. When used as a premix product, dried sand of these materials is preferred. Among these, limestone aggregate is preferred.

[0029] The fine aggregate content is preferably 40 to 300 parts by mass, more preferably 75 to 250 parts by mass, even more preferably 100 to 200 parts by mass, and even more preferably 160 to 190 parts by mass, per 100 parts by mass of cement.

[0030] The water-reducing agent used in this invention improves fluidity retention. While there are no particular limitations on the types of water-reducing agents, examples include naphthalene-based water-reducing agents, lignin-based water-reducing agents, melamine-based water-reducing agents, and polycarboxylic acid-based water-reducing agents.

[0031] The water-reducing agent content is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, and even more preferably 0.01 to 1.00 parts by mass, per 100 parts by mass of cement. By having the water-reducing agent content within the above range, a repair mortar composition with excellent water-impermeableness and salt resistance can be obtained.

[0032] The fibers used in this invention improve the ability to apply thick coatings and crack resistance. The types of fibers are not particularly limited, but examples include polymer fibers such as vinylon fibers, propylene fibers, acrylic fibers, nylon fibers, and aramid fibers, as well as inorganic fibers such as steel fibers, glass fibers, carbon fibers, and fibers produced by melt-spun basalt and other rocks.

[0033] The fiber content is preferably 0.02 to 1.5 parts by mass, more preferably 0.05 to 1.0 parts by mass, and even more preferably 1.4 to 1.8 parts by mass, per 100 parts by mass of cement mortar. A fiber content above the lower limit allows for sufficient improvement of sagging properties. Furthermore, a fiber content below the upper limit allows for good resistance to mixing. From the viewpoint of improving the ability to apply thick coats and crack resistance, the fiber length is preferably 3 mm or longer, and more preferably 5 mm or longer. Furthermore, from the viewpoint of the aesthetic appearance of the trowel-finished surface, the fiber length is preferably 15 mm or less, and more preferably 12 mm or less.

[0034] The cement admixture polymer used in the present invention is not particularly limited, but examples include rubber latex such as acrylonitrile-butadiene rubber, styrene-butadiene rubber, chloroprene rubber, and natural rubber, as well as resin emulsions such as ethylene-vinyl acetate copolymer, polyacrylic acid ester, styrene-acrylic acid ester copolymer, acrylic acid ester copolymer represented by acrylonitrile-acrylic acid ester, and vinyl acetate vinyl transate copolymer. Polymers used for cement admixture come in various forms, including re-emulsifying powders and liquids, and are used to improve adhesion to the substrate and enhance the durability of the mortar.

[0035] The content of the cement admixture polymer is preferably 1 to 20 parts by mass, more preferably 3 to 15 parts by mass, and even more preferably 4 to 12 parts by mass, in terms of solid content, per 100 parts by mass of cement. By having the cement admixture polymer content within the above range, mixing resistance can be reduced and neutralization resistance and adhesion strength can be improved.

[0036] The rapid-hardening material used in this invention is a mixture of a calcium aluminate compound and gypsum. The CaO / Al2O3 molar ratio of the calcium aluminate compound used as a rapid-hardening material in this invention is preferably in the range of 0.75 to 3, and more preferably in the range of 1 to 2. A CaO / Al2O3 molar ratio of 0.75 or higher provides sufficient initial strength development. A CaO / Al2O3 molar ratio of 3 or lower provides sufficient fluidity and pot life. Furthermore, for calcium aluminate compounds used as rapid hardening materials, amorphous forms are preferred, as crystalline forms may not provide sufficient strength.

[0037] The particle size of the calcium aluminate compound used as a rapid-hardening material in this invention is not particularly limited, but is typically 3,000 to 9,000 cm² in Blaine values. 2 A value of / g is preferred, and the range is 4,000 to 8,000 cm². 2A blaine value of 3,000 cm² is more preferable for calcium aluminate compounds as fast-hardening materials. 2 A value of 1 / g or higher allows for sufficient initial strength development. Furthermore, the Blaine value of the calcium aluminate compound as a rapidly hardening material is 9,000 cm². 2 Having a value of less than / g makes it easier to ensure liquidity and working time.

[0038] The gypsum used as a rapid hardening material in this invention refers collectively to anhydrous, hemihydrate, or dihydrate gypsum and is not particularly limited; however, from the viewpoint of strength development, the use of anhydrous gypsum or hemihydrate gypsum is preferred, and the use of anhydrous gypsum is more preferred.

[0039] The particle size of gypsum is not particularly limited, but it is usually between 3,000 and 9,000 cm² in Blaine values. 2 A value of / g is preferred, and the range is 4,000 to 8,000 cm². 2 / g is more preferable. The Blaine value of the gypsum is 3,000 cm³. 2 A value of 9,000 cm² or higher ensures good dimensional stability. Additionally, the Blaine value of the gypsum is 9,000 cm². 2 Having a value of less than / g makes it easier to ensure liquidity.

[0040] The preferred proportions of each component in 100 parts by mass of the binder, which consists of cement, a calcium aluminate compound as a rapid hardening agent, and gypsum, are 50 to 98 parts by mass of cement, 1 to 25 parts by mass of the calcium aluminate compound as a rapid hardening agent, and 1 to 25 parts by mass of gypsum. By keeping the proportions of each material within the above range, a repair mortar composition that satisfies the effects of the present invention, i.e., a rapid hardening repair mortar material with excellent water-impermeable and salt-impermeable properties, can be obtained.

[0041] Here, the preferred mixing ratio of calcium aluminate compound and gypsum as a rapid hardening material is 30 to 70 parts by mass of calcium aluminate compound and 70 to 30 parts by mass of gypsum per 100 parts by mass of the rapid hardening material consisting of calcium aluminate compound and gypsum, and more preferably 40 to 60 parts by mass of calcium aluminate compound and 60 to 40 parts by mass of gypsum. When the calcium aluminate compound is 30 parts by mass or more and the gypsum is 70 parts by mass or less, the initial strength development is sufficient and dimensional stability is good. Furthermore, when the calcium aluminate compound is 70 parts by mass or less and the gypsum is 30 parts by mass or more, it is easy to ensure a pot life.

[0042] The mixing ratio of the rapid-hardening agent is preferably 2 to 50 parts by mass, more preferably 4 to 25 parts by mass, and even more preferably 6 to 12 parts by mass, per 100 parts by mass of cement. By having the mixing ratio of the rapid-hardening agent within the above range, a repair mortar composition is obtained that exhibits good initial strength development, facilitates the securing of an appropriate pot life, has good resistance to material segregation, and has excellent water-impermeable and salt-resistant properties.

[0043] The water used in this invention is not particularly limited, but examples include groundwater and tap water. Water with few impurities is preferred.

[0044] The water content is not particularly limited as it varies depending on the purpose and use and the content of each material, but it is preferably 8 to 70 parts by mass, more preferably 10 to 65 parts by mass, even more preferably 12 to 60 parts by mass, and still more preferably 11 to 17 parts by mass per 100 parts by mass of the rapid-hardening repair mortar material, which consists of powder components such as cement, salt fixative, fine aggregate, calcium aluminate compound, gypsum, water-reducing agent, fiber, setting retarder, and cement admixture polymer. By having a water content above the lower limit, a decrease in fluidity can be suppressed and an extremely large amount of heat generation can be suppressed. Furthermore, by having a water content below the upper limit, strength development can be ensured.

[0045] In the present invention, one or more of the following can be used, to the extent that they do not adversely affect performance: gas foaming substances, expanding agents, setting regulators, quick setting agents, air-entraining agents, rust inhibitors, water-repellent agents, antibacterial agents, colorants, antifreeze agents, defoaming agents, limestone fine powder, siliceous fine powder, blast furnace slow-cooling slag fine powder, sewage sludge incineration ash and its molten slag, municipal solid waste incineration ash and its molten slag, and pulp sludge incineration ash and other admixtures, as well as shrinkage reducing agents, clay minerals such as bentonite and sepiolite, and anion exchangers such as hydrotalcite, to the extent that they do not substantially hinder the objective of the present invention.

[0046] The method of mixing each material in the repair mortar composition is not particularly limited; each material may be mixed at the time of application, or some or all of them may be mixed in advance. When pre-mixing powder components, any existing mixing equipment, such as a tilting cylinder mixer, omni mixer, Henschel mixer, V-type mixer, and Nauta mixer, can be used. The method for mixing the powder components with water can be any method, such as putting the materials into a container like a pail and mixing them with a hand mixer, or mixing them using a mortar mixer, omni mixer, pan mixer, ball mixer with a spherical curved bottom, a ball mixer, a ball mixer with a pan shape and rotating blades, or a twin-shaft mixer used for mixing concrete. A mixing time of 90 seconds or more is preferable, and 120 seconds or more is more preferable. Mixing for 90 seconds or more ensures uniform repair.

[0047] The repair mortar composition of the present invention satisfies the following adhesion test results. [Adhesion test] As shown in Figure 1(a), a repair mortar composition 2' is sprayed onto the top surface 1A of a rectangular prism concrete 1 with a bottom surface 1B and top surface 1A measuring 300 mm x 300 mm and a height of 60 mm. The composition of concrete 1 is as follows: 100 parts by mass of cement, 290 parts by mass of fine aggregate, 330 parts by mass of coarse aggregate, 1 part by mass of admixture, and 55 parts by mass of water. Ordinary cement is used as the cement, silica sand as the fine aggregate, river gravel as the coarse aggregate, and a water-reducing agent as the admixture. Then, as shown in Figure 1(b), the repair mortar composition 2' is sprayed until the height reaches 60 mm to create a preliminary test specimen 10 of a rectangular prism with a bottom surface 1B and top surface 1A measuring 300 mm x 300 mm and a height of 120 mm. The adhesion strength of the prepared preliminary test specimen 10 is measured using the following adhesion strength measurement method. [Method for measuring adhesion strength] The method for measuring adhesion strength involves first making a 70mm cut into the concrete side of the repair mortar composition from the surface to be cast using a concrete core drill with an inner diameter of φ55mm. A φ55mm steel adhesion jig is then attached to the cut surface, and the maximum load is measured using a building research institute type adhesion strength tester to calculate the adhesion strength. The adhesion strength at 28 days of age is 1.3 N / mm². 2 If the bond strength is less than 1.3 N / mm², the interface becomes weak, and the repair mortar composition cannot be considered to have long-term durability. Therefore, in order for a repair mortar composition to be salt-resistant and have long-term durability, the adhesion strength of the repair mortar composition must be 1.3 N / mm². 2 Preferably, it is 1.4 N / mm 2 It is more preferable that the above is true, and 1.5 N / mm 2 It is even more preferable that the above conditions are met.

[0048] The repair mortar composition of the present invention satisfies the following thickness-applying properties. [Thick coating test] As shown in Figure 3(a), a rectangular mortar board 40 with a bottom and top surface measuring 70 mm x 70 mm and a height of 20 mm, a wooden frame 41 with an opening of 60 mm in diameter, and a steel adhesive jig 42 for fixing the mortar board 40 to the wooden frame 41 are prepared. The composition of the mortar board is 100 parts by mass of cement, 300 parts by mass of fine aggregate, and 50 parts by mass of water. Ordinary cement is used as the cement, and standard sand is used as the fine aggregate. As shown in Figure 3(b), the mortar board 40 is placed so as to close the opening of the wooden frame 41, and the steel adhesive jig 42 is placed on the top surface of the mortar board 40. As shown in Figure 3(c), the repair mortar composition is sprayed until the height of the part 43 made of the repair mortar composition reaches 60 mm, and the thickness of the prepared test specimen is measured using the thickness of the composition measurement method described below. [Method for measuring coating thickness] The method for measuring the thickness of the coating involves attaching a steel adhesion jig to the back of the mortar board, measuring the maximum load using a building research institute-type adhesion strength tester, and calculating the adhesion strength. Adhesion strength at 24 hours of age: 1.0 N / mm 2 If the bond strength is less than 1.0 N / mm², the interface becomes weak, and the repair mortar composition cannot be considered to have long-term durability. Therefore, in order for a repair mortar composition to be salt-resistant and have long-term durability, the adhesion strength of the repair mortar composition must be 1.0 N / mm². 2 Preferably, it is 1.1 N / mm 2 It is more preferable that the value be greater than or equal to 1.2 N / mm 2 It is even more preferable that the above conditions are met.

[0049] The repair mortar composition of the present invention satisfies the following setting time results. [Setting Time Test] A 100mm x 100mm x 100mm test specimen is prepared by spraying the repair mortar composition onto a 100mm x 100mm x 100mm formwork until it reaches a height of 100mm. The penetration resistance of the prepared test specimen is measured using the following setting time measurement method. [Measurement method of setting time] The setting time is measured using a Proctor penetration resistance tester, where the penetration resistance value is 3.5 N / mm². 2Measure the time it takes to reach that point. It is between 10 minutes and 1 hour. Penetration resistance value is 3.5 N / mm 2 If the setting time is less than 10 minutes, it becomes impossible to properly finish the trowel surface after spraying. Furthermore, if it exceeds 1 hour, the interface becomes fragile, and the repair mortar composition cannot be said to have long-term durability. Therefore, in order to obtain a repair mortar composition that is salt-resistant and has long-term durability, the setting time of the repair mortar composition is preferably between 10 minutes and 1 hour, and more preferably between 15 minutes and 50 minutes.

[0050] The repair mortar composition of the present invention satisfies the following chloride ion penetration depth test results. [Chloride ion penetration depth test] As shown in Figure 1(a), a repair mortar composition 2' is sprayed onto the top surface 1A of a rectangular prism concrete 1 with a bottom surface 1B and top surface 1A measuring 300 mm x 300 mm and a height of 60 mm. The composition of concrete 1 is as follows: 100 parts by mass of cement, 290 parts by mass of fine aggregate, 330 parts by mass of coarse aggregate, 1 part by mass of admixture, and 55 parts by mass of water. Ordinary cement is used as the cement, silica sand as the fine aggregate, river gravel as the coarse aggregate, and a water-reducing agent as the admixture. Then, as shown in Figure 1(b), the repair mortar composition 2' is sprayed until the height reaches 60 mm to create a preliminary test specimen 10 of a rectangular prism with a bottom surface 1B and top surface 1A measuring 300 mm x 300 mm and a height of 120 mm. As shown in Figure 2(a), the prepared preliminary test specimen 10 is cut so that the portion 2, consisting of concrete 1 and repair mortar composition, has the same volume in the height direction, and as shown in Figure 2(b), it is cut to a cubic test specimen measuring 120 mm in length, 120 mm in width, and 120 mm in height. The prepared cubic test specimen 20 is immersed in seawater with a salinity of 3.5%, and after 28 days, the chloride ion penetration depth of portion 2, consisting of repair mortar composition, and the chloride ion penetration depth of portion 1, consisting of concrete, of the cubic test specimen 20 are measured using the following chloride ion penetration depth measurement method. Then, the chloride ion penetration depth of portion 2, consisting of repair mortar composition, and the chloride ion penetration depth of portion 1, consisting of concrete, of the cubic test specimen 20 are compared after 28 days. [Method for measuring chloride ion penetration depth] The method for measuring chloride ion penetration depth involves first immersing a cubic test specimen 20 in seawater with a salinity of 3.5% for 28 days. As shown in Figure 2(b), the specimen is then split perpendicular to the interface between concrete 1 and part 2, which consists of a repair mortar composition. A 0.1% aqueous solution of sodium fluorescein and a 0.1 mol / L silver nitrate solution are sprayed onto the split surface, and the areas that fluoresce are identified as chloride ion penetration zones. For both concrete 1 and part 2, the depth from the surface of the test specimen to the area that does not fluoresce is measured using calipers at nine locations (a-i, j-r) at 20 mm intervals, as shown in Figure 2(c). The average value of the nine measurements (a-i, j-r) is taken as the chloride ion penetration depth. If the chloride ion penetration depth of part 2, which consists of the repair mortar composition, exceeds 35% compared to the chloride ion penetration depth of concrete 1, then the repair mortar composition lacks salt resistance and cannot be said to have long-term durability. Therefore, in order for a repair mortar composition to have salt resistance and long-term durability, it is preferable that the chloride ion penetration depth of the repair mortar composition be 33% or less, more preferably 31% or less, and even more preferably 29% or less compared to the chloride ion penetration depth of concrete.

[0051] The repair mortar composition of the present invention has a permeability coefficient of 200 × 10⁻¹⁰ obtained by the following permeability coefficient test. -10 Preferably, the speed is 175 × 10 -10 It is more preferable that the rate is less than or equal to cm / sec, and 150 × 10 -10 It is even more preferable that the permeability coefficient is less than or equal to cm / sec. Having a permeability coefficient of less than or equal to the above upper limit of the repair mortar composition prevents water containing salt from entering and provides excellent salt resistance. [Hydroelectric coefficient test] As shown in Figure 1(a), a repair mortar composition 2' is sprayed onto the top surface 1A of a rectangular prism concrete 1 with a bottom surface 1B and top surface 1A measuring 300 mm x 300 mm and a height of 60 mm. The composition of concrete 1 is as follows: 100 parts by mass of cement, 290 parts by mass of fine aggregate, 330 parts by mass of coarse aggregate, 1 part by mass of admixture, and 55 parts by mass of water. Ordinary cement is used as the cement, silica sand as the fine aggregate, river gravel as the coarse aggregate, and a water-reducing agent as the admixture. Then, as shown in Figure 1(b), the repair mortar composition 2' is sprayed until the height reaches 60 mm to create a preliminary test specimen 10 of a rectangular prism with a bottom surface 1B and top surface 1A measuring 300 mm x 300 mm and a height of 120 mm. Then, as shown in Figure 4(a), the prepared provisional test specimen 10 is divided into two parts, the part 2 consisting of concrete 1 and repair mortar composition, by the diameter of the bottom and top surfaces, and cut out so that the volume is the same in the height direction, and as shown in Figure 4(b), it is cut to a cylindrical test specimen 30 with a diameter of 100 mm on the bottom and top surfaces and a height of 300 mm. The bottom and top sides of the obtained cylindrical test specimen 30 are cut, and as shown in Figure 4(c), it is cut to a cylindrical test specimen 31 with a diameter of 100 mm on the bottom and top surfaces and a height of 150 mm. The permeability coefficient of the prepared cylindrical test specimen 31 is measured by the following permeability coefficient measurement method. [Method for measuring the permeability coefficient] The method for measuring the permeability coefficient involves first placing a cylindrical test specimen 31 in a test container (not shown), filling the gap between the sides of the cylindrical test specimen 31 and the test container with grout material to maintain watertightness, and then pressurizing the top surface of the cylindrical test specimen 31 with water at a pressure of 1 MPa for 48 hours. After 48 hours of pressurization, the mass of the drainage from the bottom surface of the cylindrical test specimen is measured to determine the permeability Q (mL / sec), and the permeability coefficient K is calculated using the following formula 1. ρ is the unit weight of water (g / cm³). 3 ), P is water pressure (kg / cm 2 ), A is the cross-sectional area (cm²) of the cylindrical test specimen. 2 ), where h is the height (cm) of the cylindrical test specimen. K = ρhQ / PA ... (Equation 1) [Examples]

[0052] The present invention will be further described below based on experimental examples, but the present invention is not limited thereto.

[0053] [Experimental Example 1] A repair mortar material was prepared by adding 190 parts by mass of fine aggregate, 0.05 parts by mass of water-reducing agent, 1.6 parts by mass of fiber, and 10 parts by mass of rapid-hardening agent to 100 parts by mass of cement, and by adding the cement admixture polymer and salt fixative in the amounts shown in Table 1 per 100 parts by mass of cement. A repair mortar composition was prepared by mixing 100 parts by mass of the obtained repair mortar material with 14 parts by mass of water. The adhesion strength, thickness application, setting time, chloride ion penetration depth, and water permeability coefficient of the prepared repair mortar composition were measured. The results are shown in Table 1.

[0054] <Materials used> • Cement: Ordinary Portland cement (manufactured by Denka), Blaine value 3,300 cm² 2 / g • Fine aggregate: A mixture of lime sand, 50% of which was 0.6 mm or smaller, and 50% of which was 0.6-1.2 mm in size, was used. • Salt fixative mainly composed of CaO·2Al2O3: Calcium aluminate compound, CaO / Al2O3 molar ratio 0.5, Blaine value 3,500 cm² 2 / g • Water-reducing agent: Naphthalene-based water-reducing agent, commercially available product ("Selflo-110P" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) • Fiber: Vinylon fiber, fiber length 6mm, fineness 6.6 dtex, dry strength 1,850 N / mm 2 Dry stretch 6.0% • Polymer for cement admixture: Polyacrylic acid ester re-emulsifying resin, commercially available, moisture content 0.8%, density 0.5 g / mL • Water: Tap water • Rapid-hardening material: Calcium aluminate compound, CaO / Al2O3 molar ratio 1.70, ignition loss 1.0%, crystalline, main components CaO·Al2O3 and 12CaO·7Al2O3, Blaine value 5,000 cm² 2 / g

[0055] <Measurement items> • Adhesion strength: For test specimens aged 28 days, a 70mm cut was made into the concrete side from the surface where the repair mortar composition was cast using a concrete core drill with an inner diameter of φ55mm. A φ55mm steel adhesion jig was attached to the cut surface, and the maximum load was measured using a building research institute type adhesion strength tester to calculate the adhesion strength. • Thick application properties: A wooden frame with a 60mm diameter opening on the top surface of a rectangular mortar board with a bottom and top surface measuring 70mm x 70mm and a height of 20mm was installed, and a repair mortar composition was sprayed onto it until it reached a height of 60mm to create a test specimen. The adhesion strength after 24 hours was measured. • Setting time: A 100mm x 100mm x 100mm test specimen was prepared by spraying the repair mortar composition, and the penetration resistance value was 3.5 N / mm². 2 The time it took to reach that point was measured. • Chloride ion penetration depth: Cubic test specimens immersed in seawater with a salinity of 3.5% for 28, 56, and 91 days were split perpendicular to the interface between the concrete and repair mortar composition to divide them into two halves. A 0.1% aqueous solution of sodium fluorescein and a 0.1 mol / L silver nitrate solution were sprayed onto the split surfaces, and the areas that fluoresced were designated as the chloride ion penetration zones. For the concrete and repair mortar composition sections, the depth from the surface of the test specimen to the area that did not fluoresce was measured at nine equally spaced locations using calipers. The average value of the nine measured locations was defined as the chloride ion penetration depth. • Permeability coefficient: A cylindrical specimen was placed in a test container, and the space between the sides of the cylindrical specimen and the test container was filled with grout material (Denka Co., Ltd., Highpretascon T-1S) to maintain watertightness. Water was pressurized from the top surface of the cylindrical specimen at a water pressure of 1 MPa for 48 hours. After 48 hours of pressurization, the mass of the drainage from the bottom surface of the cylindrical specimen was measured to determine the permeability Q (mL / sec), and the permeability coefficient K was calculated using Equation 1 below. ρ is the unit weight of water (g / cm³). 3 ), P is water pressure (kg / cm 2 ), A is the cross-sectional area (cm²) of the cylindrical test specimen. 2 ), where h is the height (cm) of the cylindrical test specimen. K = ρhQ / PA ... (Equation 1)

[0056] [Table 1]

[0057] The results in Table 1 confirm that using a repair mortar composition containing specific materials and meeting the results of adhesion strength, thickness test, setting time test, and chloride ion penetration depth measured by specific methods can provide excellent long-term salt resistance. Furthermore, it was confirmed that using a repair mortar composition with a permeability coefficient measured by a specific method can further enhance long-term salt resistance. [Industrial applicability]

[0058] This invention provides a repair method that strengthens the interface between concrete and the repair mortar composition, thereby improving long-term salt resistance, and allows for stable and uniform application of the repair mortar composition. This is achieved by spraying a repair mortar composition containing specific materials onto areas of existing structures excluding deteriorated parts, and satisfying the results of adhesion strength, thickness application tests, setting time tests, and chloride ion penetration depth tests, all measured using specific methods. Therefore, it can be widely applied to repair methods for existing concrete structures used in railways, roads, and other infrastructure. [Explanation of symbols]

[0059] 1: Concrete 2': Repair mortar composition 2: Parts made of repair mortar composition 10: Provisional test specimen 20: Cube-shaped test specimen 30,31: Cylindrical test specimens 40: Mortar board 41: Wooden frame 42: Steel attachment jig 43: Parts consisting of repair mortar composition

Claims

1. The process includes removing deteriorated concrete from an existing structure and spraying a repair mortar composition onto the area from which the deteriorated portion was removed. The aforementioned repair mortar composition is cement, CaO・2Al ２ O ３ It contains a salt fixative as the main component, fine aggregate, water-reducing agent, fibers, cement admixture polymer, rapid hardening agent, and water. The aforementioned repair mortar composition is a repair method for deteriorated parts of existing structures that satisfies the results of the following adhesion test, thickness test, setting time test, and chloride ion penetration depth test. [Adhesion test] A preliminary test specimen of a rectangular prism with a height of 120 mm was prepared by spraying the repair mortar composition onto the top surface of a rectangular prism concrete with a bottom and top surface of 300 mm x 300 mm and a height of 60 mm until it reached a height of 60 mm. The adhesion strength at 28 days was 1.3 N / mm². ２ That's all. [Thick coating test] A wooden frame was installed on the top surface of a rectangular mortar board with a 70 mm x 70 mm square bottom and top surface and a height of 20 mm. The repair mortar composition was sprayed onto the frame until it reached a height of 60 mm to create a test specimen. The adhesion strength at 24 hours was 1.0 N / mm². ２ That's all. [Setting time test] The aforementioned repair mortar composition was sprayed to create a 100 mm x 100 mm x 100 mm test specimen, and the penetration resistance value was 3.5 N / mm². ２ The time taken to reach this point is between 10 minutes and 1 hour. [Chloride ion penetration depth test] A preliminary test specimen is prepared in the shape of a rectangular prism with a height of 120 mm, by spraying the repair mortar composition onto the top surface of a rectangular concrete prism with a top and bottom surface of 300 mm x 300 mm and a height of 60 mm until it reaches a height of 60 mm. A cubic test specimen is prepared by cutting the prepared preliminary test specimen to 120 mm (length) x 120 mm (width) x 120 mm (height) such that the portion made of concrete and the portion made of the repair mortar composition have the same volume in the height direction. The prepared cubic test specimen is immersed in seawater with a salinity of 3.5%, and after 28 days, the chloride ion penetration depth of the portion made of the repair mortar composition of the cubic test specimen is 35% or less compared to the chloride ion penetration depth of the portion made of concrete of the cubic test specimen.

2. The aforementioned repair mortar composition has a permeability coefficient of 200 × 10⁻¹⁰ obtained by the following permeability coefficient test. －１０ A repair method for deteriorated parts of existing structures according to claim 1, wherein the pressure is less than or equal to cm / sec. [Hydroelectric coefficient test] A rectangular prism concrete with a bottom and top surface measuring 300 mm x 300 mm square and a height of 60 mm is sprayed onto the top surface until it reaches a height of 60 mm, thereby creating a temporary rectangular prism test specimen with a bottom and top surface measuring 300 mm x 300 mm square and a height of 120 mm. The prepared temporary test specimen is then cut into two sections, each consisting of the concrete and the repair mortar composition, at the diameter of the bottom and top surfaces, and has the same volume in the height direction. A cylindrical test specimen is then prepared by cutting it to a size of 100 mm in diameter and 150 mm in height, and the permeability coefficient of the prepared cylindrical test specimen is measured.

3. The repair method for deteriorated parts of existing structures according to claim 1 or 2, wherein in the step of spraying the repair mortar composition, the spraying speed of the repair mortar composition is 5 to 25 L / min.

4. The repair method for deteriorated parts of existing structures according to claim 1 or 2, wherein in the step of spraying the repair mortar composition, the pressure of the pump that pumps the repair mortar composition is 2 MPa or less.

5. A repair mortar composition for use in the repair method for deteriorated parts of existing structures according to claim 1 or 2, CaO・2Al per 100 parts by mass of cement ２ O ３ A repair mortar composition comprising a repair mortar material comprising 4 to 10 parts by mass of a salt fixing agent mainly composed of, 160 to 190 parts by mass of fine aggregate, 0.01 to 1.00 parts by mass of a water-reducing agent, 1.4 to 1.8 parts by mass of fiber, 4 to 12 parts by mass of a polymer for cement admixture, and 6 to 12 parts by mass of a rapid-hardening agent, and 11 to 17 parts by mass of water per 100 parts by mass of the repair mortar material.

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