Peeling prevention method

Abstract

To provide an exfoliation prevention method that can be secured to be compatible with work's safety and adhesion workability of an exfoliation prevention sheet 2 even when applying an epoxy resin based adhesive 4 onto the surface of a concrete structure 1 located above worker's head.SOLUTION: An exfoliation prevention method for bonding an exfoliation prevention sheet 2 onto the surface of a concrete structure 1 to reinforce the surface of the concrete structure 1 comprises: a mixture step of mixing a high viscous and solid like hardening agent comparative to a liquid hardening agent in a high viscous and solid like main agent comparative to a liquid main agent to form an epoxy resin based adhesive 4; an application step of applying the epoxy resin based adhesive 4 to the surface of the concrete structure 1 or the exfoliation prevention sheet 2; and an attachment step of attaching the exfoliation prevention sheet 2 onto the surface of the concrete structure 1.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a spalling prevention method for preventing concrete from spalling, for example, by adhering a spalling prevention sheet to the inner wall of a concrete tunnel, thereby reinforcing the inner wall of the concrete tunnel. [Background technology]

[0002] For example, in concrete structures such as concrete tunnels, cracks can occur on the surface due to neutralization of concrete, alkali-aggregate reaction, or vibrations caused by the passage of vehicles or earthquakes.

[0003] Furthermore, if a crack occurs on the surface of a concrete structure, a part of the concrete structure may spall off due to vibrations caused by the passage of vehicles, earthquakes, etc. Therefore, various technologies have been proposed to prevent spalling of concrete.

[0004] For example, Patent Document 1 proposes a technology for preventing concrete from spalling by adhering a triaxial mesh-shaped anti-splitting sheet to the surface of a concrete structure coated with an epoxy resin-based adhesive, thereby reinforcing the surface of the concrete structure.

[0005] Incidentally, the anti-fall sheet may be attached to the surface of a concrete structure located above the heads of workers, such as the ceiling of a concrete tunnel or the bottom surface of a deck. In this case, if the viscosity of the epoxy resin adhesive is low, the epoxy resin adhesive applied to the surface of the concrete structure may drip down toward the worker working directly below.

[0006] In such a case, the thickness of the applied epoxy resin adhesive is not stable, making it difficult to ensure the desired thickness. Furthermore, not only does the dripping epoxy resin adhesive adhere to the worker, but the dripping epoxy resin adhesive may also interfere with the work of adhering the peel-prevention sheet. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 4919654 Summary of the Invention [Problem to be solved by the invention]

[0008] In view of the above-mentioned problems, the present invention aims to provide a peeling prevention method that can ensure both work safety and ease of application of a peeling prevention sheet, even when an epoxy resin-based adhesive is applied to the surface of a concrete structure located above the worker's head. [Means for solving the problem]

[0009] This invention is a spalling prevention method for reinforcing the surface of a concrete structure by adhering a spalling prevention sheet to the surface of the concrete structure, and the method is characterized in that the sheet has a higher viscosity than a liquid base agent, In the Fire Service Act Hazard Confirmation Test (Chapter 3 Other Confirmation Methods), the product is judged to be not liquid at temperatures between 20℃ and 40℃. The solid base agent has a higher viscosity than the liquid hardener. In the Fire Service Act Hazard Confirmation Test (Chapter 3 Other Confirmation Methods), the product is determined to be not liquid at temperatures between 20°C and 40°C. The method includes a mixing step of mixing a solid curing agent to produce an epoxy resin adhesive, a coating step of coating the epoxy resin adhesive on the surface of the concrete structure or on the peeling prevention sheet, and a pasting step of pasting the peeling prevention sheet on the surface of the concrete structure. The base agent contains 5% to 10% of an additive for adjusting viscosity, and the curing agent contains 5% to 10% of an additive for adjusting viscosity. It is characterized by:

[0010] The concrete structures include, for example, concrete tunnels, concrete buildings, box culverts, roads and walkways, bridge piers, and bridge girders. The above-mentioned peel-preventing sheet refers to a peel-preventing sheet in the form of a sheet, film, or thin plate.

[0011] The above-mentioned "solid" refers to a state in which the material has low fluidity and is not rigid, and is determined to be not liquid at temperatures between 20°C and 40°C when checking for liquidity in the Fire Service Act hazard confirmation test (Chapter 3: Other confirmation methods).

[0012] According to this invention, the anti-peeling method can ensure both work safety and ease of application of the anti-peeling sheet, even when an epoxy resin-based adhesive is applied to the surface of a concrete structure located above the worker's head.

[0013] Specifically, because a solid base agent and a solid curing agent are mixed, the epoxy resin adhesive has a higher viscosity during its pot life than, for example, an epoxy resin adhesive that is a mixture of a liquid base agent and a liquid curing agent.

[0014] For this reason, the epoxy resin adhesive can maintain its applied state even when applied thickly to the surface of a concrete structure or to a spallation prevention sheet. As a result, even when, for example, an epoxy resin-based adhesive is applied to the surface of a concrete structure located above a worker's head, the anti-peeling method can prevent the epoxy resin-based adhesive from dripping from the surface of the concrete structure.

[0015] Alternatively, even when a peeling prevention sheet coated with an epoxy resin-based adhesive is attached to the surface of a concrete structure, the peeling prevention method can prevent the epoxy resin-based adhesive from dripping from the peeling prevention sheet.

[0016] Therefore, the anti-peeling method can prevent the epoxy resin adhesive from adhering to workers and can also prevent work from being hindered by the epoxy resin adhesive dripping.

[0017] Furthermore, due to the viscosity of the epoxy resin-based adhesive, the anti-peeling method can prevent the anti-peeling sheet attached to the surface of the concrete structure from shifting from the desired position or peeling off, thereby improving workability.

[0018] Therefore, the anti-peeling method can ensure both work safety and ease of application of the anti-peeling sheet, even when applying an epoxy resin-based adhesive to the surface of a concrete structure located above the workers' heads.

[0019] In addition, according to the flowchart for hazardous materials confirmation testing posted on the website of the Fire and Disaster Management Agency of the Ministry of Internal Affairs and Communications in Japan (https: / / www.fdma.go.jp / relocation / kasai_yobo / about_shiken_unpan / kakuninkiken.html), the solid base agent and solid hardener do not fall under the category of Class 4 hazardous materials under the Fire Service Act, at least in Japan, but rather fall under Class 2 hazardous materials, designated flammable materials (flammable solids), or non-hazardous materials.

[0020] For this reason, the anti-flaking method can reduce the risk of fire at the construction site compared to storing the base agent and hardener, which are classified as Class 4 hazardous materials. Furthermore, even if a malfunction occurs in the storage can, the solid base agent and hardener are unlikely to leak out of the storage can, so the anti-peeling method prevents the flames from spreading over a wide area even if the base agent or hardener ignites.

[0021] As a result, the anti-peeling method allows the amount of base agent and hardener that can be transported and stored at the construction site to be increased compared to when it falls under the category of hazardous materials of Class 4. Therefore, with the anti-peeling method, even at construction sites where the adhesion range of the anti-peeling sheet is wide and a large amount of epoxy resin adhesive is required, the base agent and hardener can be transported efficiently, making construction work more efficient.

[0022] The base agent contains 5% or more and 10% or less, preferably 7% or more and 10% or less, of an additive for adjusting viscosity, and the curing agent contains 5% or more and 10% or less, preferably 6% or more and 10% or less, of an additive for adjusting viscosity.

[0023] Therefore, the anti-peeling method can make the base agent and hardener into the desired high-viscosity solid state, while ensuring the applicability of the epoxy resin-based adhesive obtained by mixing the base agent and hardener.

[0024] As an aspect of the present invention, a defoaming step may be carried out in which the anti-exfoliation sheet attached to the surface of the concrete structure is pressed to remove air bubbles. According to this configuration, the degassing process after the application process enables the anti-exfoliation method to spread the epoxy resin-based adhesive while degassing the air trapped between the surface of the concrete structure and the anti-exfoliation sheet.

[0025] As a result, the peeling prevention method can interpose the epoxy resin adhesive without any gaps between the surface of the concrete structure and the peeling prevention sheet even if the epoxy resin adhesive is unevenly applied. Therefore, the peeling prevention method can reliably adhere the peeling prevention sheet to the surface of the concrete structure and reinforce the surface of the concrete structure.

[0026] As a further aspect of the present invention, the base agent and the curing agent may each have a flash point of 40° C. or higher. According to this configuration, the anti-peeling method can improve safety at the construction site even if the base agent and hardener are stored at the construction site.

[0027] Furthermore, the solid base agent and solid hardener are not classified as Class 2 hazardous materials under the Fire Service Act in Japan, but are classified as designated flammable materials (flammable solids) or non-hazardous materials. Therefore, the anti-flaking method can reduce the risk of fire at the construction site more than when storing the base agent and hardener, which are Class 2 hazardous materials.

[0028] As a result, the anti-peeling method allows the amount of base agent and hardener that can be transported and stored at the construction site to be increased compared to when it corresponds to Class 2 hazardous materials. Therefore, with the anti-peeling method, even at construction sites where the adhesion range of the anti-peeling sheet is wide and a large amount of epoxy resin adhesive is required, the base agent and hardener can be transported efficiently, making construction work more efficient.

[0029] In another aspect of the present invention, the anti-peeling sheet is in the form of a transparent and flexible sheet made of a coarse mesh sheet coated with a transparent resin, and the additive in the main agent and the additive in the curing agent may be amorphous silica. According to this configuration, since the anti-peeling sheet has flexibility, the anti-peeling method can, for example, roll up the anti-peeling sheet into a roll.

[0030] Therefore, the peeling prevention method makes it easier to take out the peeling prevention sheet in the required length, compared to, for example, unfolding a folded peeling prevention sheet and cutting out the required length. This improves the yield of the peeling prevention sheet, and the peeling prevention method allows the peeling prevention sheet to be used efficiently.

[0031] Furthermore, since the anti-peeling sheet is transparent, the anti-peeling method makes it easy to check the extent to which the epoxy resin-based adhesive has spread and the extent to which it has been degassed, for example, when the anti-peeling sheet attached to the surface of a concrete structure is pressed to degas it.

[0032] In addition, the base agent and hardener containing silica as an additive can make the cured epoxy resin adhesive at least semi-transparent, so the peeling prevention method can ensure the visibility of the surface of the concrete structure even after the peeling prevention sheet is adhered to the surface of the concrete structure.

[0033] As a result, the anti-fleecing construction method can further improve work efficiency and make it easier to inspect the concrete structure even after the anti-fleecing sheet has been adhered. Effect of the Invention

[0034] The present invention makes it possible to provide a peeling prevention method that can ensure both work safety and ease of application of the peeling prevention sheet, even when an epoxy resin-based adhesive is applied to the surface of a concrete structure located above the worker's head. [Brief description of the drawings]

[0035] [Figure 1] FIG. 2 is a perspective view showing the appearance of the concrete structure after construction. [Diagram 2]FIG. 2 is an explanatory diagram for explaining an outline of a peel-prevention sheet. [Diagram 3] FIG. 1 is a schematic diagram showing an outline of a cross section of a concrete structure after construction. [Figure 4] 1 is a flowchart showing the steps performed by workers in a spalling prevention method. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. 11 is a front view showing a mesh sheet in another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] An embodiment of the present invention will now be described with reference to the drawings. In this embodiment, a spalling prevention method will be described in which a spalling prevention sheet 2 is adhered to the surface of a concrete structure 1 to reinforce the surface of the concrete structure 1 and prevent the concrete from spalling.

[0037] First, a concrete structure 1 which is an object of the spalling prevention method of the present embodiment and a spalling prevention sheet 2 which is adhered to the concrete structure 1 will be described with reference to Figs. 1 to 3. Figs. 1 shows a perspective view of the concrete structure 1 after construction, FIG. 2 shows an explanatory diagram outlining the anti-fracture sheet 2, and FIG. 3 shows a schematic diagram of the cross section of the concrete structure 1 after construction.

[0038] 2(a) shows a front view of the mesh sheet 21, and FIG. 2(b) shows a schematic cross-sectional view of the peeling prevention sheet 2. Note that in FIG. 2(b), detailed illustration of the mesh sheet 21 is omitted for clarity. 1 corresponds to the upper side in this embodiment, and the lower side in FIG. 1 corresponds to the lower side in this embodiment.

[0039] As shown in FIG. 1, the concrete structure 1 is a concrete tunnel having a ceiling portion 1a located above the heads of workers, a haunch portion 1b inclined diagonally downward from one end of the ceiling portion 1a, and a side portion 1c extending downward from the lower end of the haunch portion 1b.

[0040] In this embodiment, the top surface 1a, the haunch portion 1b, and the side surface 1c are the surfaces of the concrete structure 1. Furthermore, in this embodiment, it is assumed that there is a crack near the boundary between one end of the top surface 1a and the haunch portion 1b, and the area around the crack is the construction area where the peeling prevention sheet 2 is adhered.

[0041] In addition, as shown in Figure 1, the anti-peeling sheet 2 is formed into a 0.5 mm thick sheet that has flexibility that allows it to adhere closely to the surface of the concrete structure 1 and transparency that allows workers to visually check the condition of the surface of the concrete structure 1. The peeling prevention sheet 2 is delivered to the construction site with protective films (not shown) attached to both sides in the thickness direction.

[0042] Specifically, as shown in FIG. 2, the peeling prevention sheet 2 is composed of a mesh sheet 21 having a coarse mesh pattern and a coating layer 22 in which the mesh sheet 21 is coated with a transparent acrylic resin.

[0043] As shown in FIG. 2(a), the mesh sheet 21 has a biaxial mesh shape with approximately rectangular openings, and is formed by orthogonally arranging linear fiber material made of polypropylene at predetermined intervals.

[0044] More specifically, the mesh sheet 21 is formed in a biaxial mesh shape with a plurality of first linear fiber materials 21a arranged in parallel in the horizontal direction and a plurality of second linear fiber materials 21b arranged in parallel perpendicular to the first linear fiber materials 21a. The first linear fiber materials 21a and the second linear fiber materials 21b are integrated at their intersections.

[0045] On the other hand, as shown in FIG. 2(b), the coating layer 22 closes the openings of the mesh sheet 21 and coats the mesh sheet 21 so as to form an acrylic resin layer on both sides of the mesh sheet 21.

[0046] The peeling prevention sheet 2 having the above-mentioned structure is adhered to the surface of a concrete structure 1 impregnated with a primer 3 via an epoxy resin adhesive 4, as shown in FIG.

[0047] The epoxy resin adhesive 4 used to adhere such anti-peeling sheet 2 is a two-part mixture type in which a curing agent is mixed with a base agent, as shown in Table 1, and is an adhesive that becomes a light milky white (semi-transparent) state after curing. The base agent and the hardener are stored in separate containers at the construction site, and are mixed at the construction site immediately before being applied to the concrete structure 1.

[0048] [Table 1] More specifically, the base agent is in the form of a milky white putty, as shown in Table 1. Here, putty-like refers to a state that is determined to be not liquid in the liquid state confirmation described below, and is a high-viscosity solid that is less fluid than a cream and can be stirred. As shown in Table 1, this base resin contains 70% or more and 80% or less of liquid bisphenol A type epoxy resin, and also contains a reactive diluent and amorphous silica as additives to adjust the viscosity of the base resin to the desired viscosity.

[0049] The reactive diluent is, for example, a monoglycidyl ether such as an alkyl monoglycidyl ether, an alkyl diglycidyl ether, or an alkylphenol monoglycidyl ether, or a diglycidyl ether, and is contained in an amount of 10% to 20%.

[0050] In addition, amorphous silica is mixed not only to obtain a desired viscosity but also to make the cured product milky white (semi-transparent), so the silica content is preferably 5% to 10%, more preferably 7% to 10%.

[0051] If the silica content is less than 5%, the viscosity of the epoxy resin adhesive 4 during its pot life will be low, and so when applied to the top surface 1a, for example, the adhesive will drip, reducing workability. On the other hand, if the silica content exceeds 10%, the viscosity of the epoxy resin adhesive 4 during the pot life becomes high, making it difficult to spread and reducing the applicability of the epoxy resin adhesive 4. For this reason, the silica content in the base agent is desirably 5% or more and 10% or less, preferably 7% or more and 10% or less.

[0052] The curing agent is in the form of a pale yellowish white putty and contains 40% to 75% modified aliphatic polyamine or modified alicyclic polyamine synthesized using difunctional or higher amines as raw materials, 1% to 5% alcohols such as methanol, and a total of 1% to 20% multiple difunctional amines such as meta-xylylenediamine and isophoronediamine.

[0053] Furthermore, the curing agent contains 1% to 15% of an alkylphenol such as ortho-sec-butylphenol, 1% to 10% of bisphenol A as a curing-accelerating additive, 1% to 15% of benzyl alcohol as a viscosity adjusting additive, and 5% to 10% of amorphous silica.

[0054] As an example, as shown in Table 1, the curing agent of the present embodiment contains 55% or more and 75% or less of modified aliphatic polyamine, 2.4% of methanol, and 1% or more and 8% or less of meta-xylylenediamine.

[0055] Furthermore, as shown in Table 1, the curing agent of this embodiment contains 7.0% ortho-sec-butylphenol, 9.4% isophoronediamine, 1.7% bisphenol A, and 1% or more and 3% or less of benzyl alcohol.

[0056] In addition, as shown in Table 1, the curing agent of the present embodiment contains 5% or more and 10% or less of amorphous silica as an additive for adjusting the viscosity of the curing agent to a desired viscosity. This amorphous silica is mixed not only to obtain the desired viscosity but also to make the cured product milky white (semi-transparent) in appearance, so the silica content is preferably 5% to 10%, more preferably 6% to 10%.

[0057] If the silica content is less than 5%, the viscosity of the epoxy resin adhesive 4 during its pot life will be low, and so when applied to the top surface 1a, for example, the adhesive will drip, reducing workability. On the other hand, if the silica content exceeds 10%, the viscosity of the epoxy resin adhesive 4 during the pot life becomes high, making it difficult to spread and reducing the applicability of the epoxy resin adhesive 4. For this reason, the silica content in the curing agent is desirably 5% or more and 10% or less, preferably 6% or more and 10% or less.

[0058] Next, the physical properties of the above-mentioned base agent and curing agent will be explained with reference to Table 2.

[0059] [Table 2] The liquid state confirmation shown in Table 2 was carried out based on the definition of liquid in Article 69-2 of the Regulations Concerning the Control of Hazardous Materials in Japan and the liquid state confirmation described in Chapter 3 "Other Confirmation Methods" in the Fire Service Act Hazard Confirmation Test Database (http: / / explosion-safety.jp / INFOMATION / shoubou_mokuji.htm).

[0060] More specifically, to check the liquid state, the test article (base agent or hardener) is placed in a flat-bottomed cylindrical test tube with an inner diameter of 30 mm and a height of 120 mm to a position 55 mm above the bottom of the test tube. The test tube is then placed in an upright position in a thermostatic water bath, and after the temperature of the test article has reached the confirmation temperature ±0.1°C, it is left to stand for a further 10 minutes, after which the test tube is removed from the thermostatic water bath while still upright, and quickly laid down horizontally.

[0061] In this case, the time elapsed after the test tube is laid horizontally is measured, and if the tip of the test article passes a position 85 mm from the bottom of the test tube within 90 seconds, the test article is determined to be liquid.

[0062] The classification under the Fire Service Act shown in Table 2 was based on the flowchart for the Class 4 Hazardous Materials Confirmation Test and the flowchart for the Class 2 Hazardous Materials Confirmation Test posted on the website of the Fire and Disaster Management Agency of the Ministry of Internal Affairs and Communications of Japan (https: / / www.fdma.go.jp / relocation / kasai_yobo / about_shiken_unpan / kakuninkiken.html).

[0063] More specifically, the base material is a solid between 20°C and 40°C, as shown in Table 2, and shows almost no fluidity even after 90 seconds in the liquid confirmation test. Therefore, according to the flow chart of the Class 4 Hazardous Materials Confirmation Test, the base material does not fall under Class 4 Hazardous Materials as stipulated in the Fire Service Act of Japan.

[0064] Furthermore, since the main ingredient has a flash point of 138°C, according to the flow chart for the Class 2 confirmation test, it does not fall under the category of Class 2 hazardous materials as stipulated in the Fire Service Act of Japan, and is therefore at least classified as a designated flammable material (flammable solid).

[0065] On the other hand, as shown in Table 2, the hardener hardly flows even after 90 seconds in the liquid confirmation, so it is a solid between 20°C and 40°C. Therefore, according to the flow chart of the Class 4 Hazardous Materials Confirmation Test, the hardener does not fall under Class 4 Hazardous Materials as stipulated in the Fire Service Act of Japan.

[0066] Furthermore, since the hardener has a flash point of 98°C, according to the flow chart for the Class 2 confirmation test, it does not fall under the category of Class 2 hazardous materials as stipulated in the Fire Service Act of Japan, and is therefore at least classified as a designated flammable material (flammable solid).

[0067] Next, a peeling prevention method using the above-mentioned epoxy resin adhesive 4 will be described with reference to FIGS. In addition, Figure 4 shows a flowchart of the steps performed by workers in the anti-peeling method, Figure 5 shows a schematic diagram explaining the adhesive application process, Figure 6 shows a schematic diagram explaining the sheet attachment process, and Figure 7 shows a schematic diagram explaining the degassing process.

[0068] In addition, the base agent, hardener, and anti-peeling sheet 2 are stored at the construction site in advance with the base agent and hardener contained in separate containers, and the anti-peeling sheet 2 is stored at the construction site in advance in a rolled-up state.

[0069] First, as shown in FIG. 4, in the base preparation process (step S101), workers use a sander, water jet, or the like to chip the surface of the concrete structure 1 to remove dirt and foreign matter adhering to the surface and smooth the surface of the concrete structure 1.

[0070] Furthermore, after the worker has cured the periphery of the construction area of ​​the concrete structure 1, he or she applies a primer to the surface of the concrete structure 1 using a roller or a brush, and allows the concrete structure 1 to be impregnated with the primer.

[0071] After the primer has hardened, the worker proceeds to a mixing step in which the base agent and the hardener are mixed to produce the epoxy resin adhesive 4, as shown in FIG. 4 (step S102). Specifically, the worker mixes the base agent and the hardener in a ratio of 2:1 and thoroughly stirs the mixture to produce the epoxy resin adhesive 4. At this time, the worker mixes only the amount that can be used up within the pot life.

[0072] After preparing the epoxy resin adhesive 4, the worker proceeds to an application step of applying the epoxy resin adhesive 4 to the surface of the concrete structure 1, as shown in FIG. 4 (step S103).

[0073] At this time, as shown in FIG. 5, a worker applies the epoxy resin adhesive 4 to the surface of the concrete structure 1 using a trowel 5, and spreads the epoxy resin adhesive 4 to a uniform thickness.

[0074] After applying the epoxy resin adhesive 4, the worker proceeds to an attachment step of attaching the peeling prevention sheet 2 to the surface of the concrete structure 1 as shown in FIG. 4 (Step S104). Specifically, the worker rolls up the peeling prevention sheet 2 from which one protective film has been removed, as shown in Fig. 6. After that, the worker unfolds the rolled up peeling prevention sheet 2 and applies it from the top surface 1a to the haunch 1b of the concrete structure 1. Note that the peeling prevention sheet 2 is assumed to be pre-cut to an appropriate size according to the construction range.

[0075] After the peel-prevention sheet 2 is attached, the process proceeds to a defoaming step in which the worker presses the peel-prevention sheet 2 to remove air bubbles, as shown in FIG. 4 (step S105). Specifically, as shown in Figure 7, the worker presses the anti-exfoliation sheet 2 using a roller 6 or the like to push out any air bubbles that are trapped between the surface of the concrete structure 1 and the anti-exfoliation sheet 2 to the outside, thereby degassing the air bubbles.

[0076] At this time, the worker degasses the peel-prevention sheet 2 while pressing the sheet so that the surface of the sheet becomes smooth. Thereafter, the worker removes the epoxy resin adhesive 4 that has protruded from the anti-peeling sheet 2, and then peels off the other protective film of the anti-peeling sheet 2 to complete the installation work.

[0077] When the epoxy resin adhesive 4 applied to the surface of the concrete structure 1 hardens, the anti-spreading sheet 2 is firmly adhered to the surface of the concrete structure 1, reinforcing the concrete structure 1 and preventing the concrete from spalling.

[0078] As described above, the spalling prevention method of the present embodiment is a method for reinforcing the surface of a concrete structure 1 by adhering a spalling prevention sheet 2 to the surface of the concrete structure 1. This anti-peeling method involves a mixing process (step S102) in which a solid base agent, which has a higher viscosity than a liquid base agent, is mixed with a solid hardener, which has a higher viscosity than a liquid hardener, to produce an epoxy resin-based adhesive 4.

[0079] Furthermore, the anti-peeling method includes an application process (step S103) of applying an epoxy resin-based adhesive 4 to the surface of the concrete structure 1 or to the anti-peeling sheet 2, and an attachment process (step S104) of attaching the anti-peeling sheet 2 to the surface of the concrete structure 1.

[0080] According to this configuration, the anti-peeling method can ensure both work safety and ease of adhesion of the anti-peeling sheet 2, even when applying an epoxy resin-based adhesive 4 to the surface of a concrete structure 1 located above the worker's head.

[0081] Specifically, since a solid base agent and a solid curing agent are mixed, the epoxy resin adhesive 4 has a higher viscosity during its pot life than, for example, an epoxy resin adhesive made by mixing a liquid base agent and a liquid curing agent.

[0082] Therefore, even if the epoxy resin adhesive 4 is applied thickly to the surface of the concrete structure 1, the applied state can be maintained. As a result, even when the epoxy resin adhesive 4 is applied to the surface of a concrete structure 1 located above a worker's head, the anti-peeling method can prevent the epoxy resin adhesive 4 from dripping from the surface of the concrete structure 1.

[0083] Therefore, the peeling prevention method can prevent the epoxy resin adhesive 4 from adhering to workers, and can also prevent work from being hindered by the epoxy resin adhesive 4 dripping down.

[0084] Furthermore, due to the viscosity of the epoxy resin adhesive 4, the anti-peeling method can prevent the anti-peeling sheet 2 attached to the surface of the concrete structure 1 from shifting from the desired position or peeling off, thereby improving workability.

[0085] Therefore, the anti-peeling method can ensure both work safety and ease of adhesion of the anti-peeling sheet 2, even when applying an epoxy resin-based adhesive 4 to the surface of a concrete structure 1 located above the worker's head.

[0086] In addition, according to the flowchart for hazardous materials confirmation testing posted on the website of the Fire and Disaster Management Agency of Japan's Ministry of Internal Affairs and Communications, the solid base agent and solid hardener do not fall under the category of Class 4 hazardous materials under the Fire Service Act, at least in Japan, but rather fall under Class 2 hazardous materials, designated flammable materials (flammable solids), or non-hazardous materials.

[0087] For this reason, the anti-flaking method can reduce the risk of fire at the construction site compared to storing the base agent and hardener, which are classified as Class 4 hazardous materials. Furthermore, even if a malfunction occurs in the storage can, the solid base agent and hardener are unlikely to leak out of the storage can, so the anti-peeling method prevents the flames from spreading over a wide area even if the base agent or hardener ignites.

[0088] As a result, the anti-peeling method can increase the quantities of base agent and hardener that can be transported and stored at the construction site compared to when they are classified as Class 4 hazardous materials. Therefore, with the anti-peeling method, even at a construction site where the adhesion range of the anti-peeling sheet 2 is wide and a large amount of epoxy resin adhesive 4 is required, the base agent and hardener can be transported efficiently, making the construction work more efficient.

[0089] The spalling prevention method also includes a defoaming step (step S105) in which the spalling prevention sheet 2 attached to the surface of the concrete structure 1 is pressed to remove bubbles. According to this configuration, by performing the degassing process after the attachment process, the anti-exfoliation method can spread the epoxy resin-based adhesive 4 while degassing the air that is interposed between the surface of the concrete structure 1 and the anti-exfoliation sheet 2.

[0090] As a result, even if the epoxy resin adhesive 4 is unevenly applied, the peeling prevention method can interpose the epoxy resin adhesive 4 without any gaps between the surface of the concrete structure 1 and the peeling prevention sheet 2. Therefore, the peeling prevention method can reliably adhere the peeling prevention sheet 2 to the surface of the concrete structure 1, thereby reinforcing the surface of the concrete structure 1.

[0091] In addition, the base resin and curing agent each have a flash point of 40°C or higher. According to this configuration, the anti-peeling method can improve safety at the construction site even if the base agent and hardener are stored at the construction site.

[0092] Furthermore, the solid base agent and solid hardener are not classified as Class 2 hazardous materials under the Fire Service Act in Japan, but are classified as designated flammable materials (flammable solids) or non-hazardous materials. Therefore, the anti-flaking method can reduce the risk of fire at the construction site more than when storing the base agent and hardener, which are Class 2 hazardous materials.

[0093] As a result, the anti-peeling method can increase the quantities of base agent and hardener that can be transported and stored at the construction site compared to when they are classified as Class 2 hazardous materials. Therefore, with the anti-peeling method, even at a construction site where the adhesion range of the anti-peeling sheet 2 is wide and a large amount of epoxy resin adhesive 4 is required, the base agent and hardener can be transported efficiently, making the construction work more efficient.

[0094] In addition, the main agent contains 5% or more and 10% or less, preferably 7% or more and 10% or less, of an additive (silica) for adjusting viscosity. Further, the curing agent contains 5% or more and 10% or less, preferably 6% or more and 10% or less, of an additive (silica) for adjusting viscosity.

[0095] According to this configuration, the peeling prevention method can make the main agent and the curing agent into a solid state with a desired high viscosity, and can ensure the coatability of the epoxy resin adhesive 4 obtained by mixing the main agent and the curing agent.

[0096] In addition, the peeling prevention sheet 2 has a sheet shape with transparency and flexibility obtained by coating a coarse mesh sheet with a transparent resin. Further, the additive of the main agent and the additive of the curing agent are amorphous silica. According to this configuration, since the peeling prevention sheet 2 has flexibility, the peeling prevention method can, for example, roll up the peeling prevention sheet 2.

[0097] Therefore, the peeling prevention method can easily take out the peeling prevention sheet 2 by a required length as compared with, for example, the case of unfolding the folded peeling prevention sheet 2 and cutting out a required length. As a result, the yield of the peeling prevention sheet 2 is improved, and the peeling prevention method can efficiently use the peeling prevention sheet 2.

[0098] Furthermore, since the peeling prevention sheet 2 has transparency, the peeling prevention method can easily confirm the spreading state and the defoaming state of the epoxy resin adhesive 4 when, for example, pressing and defoaming the peeling prevention sheet 2 attached to the surface of the concrete structure 1.

[0099] In addition, the main agent and the curing agent containing silica as an additive can make the cured epoxy resin adhesive 4 at least translucent. Therefore, the peeling prevention method can ensure the visibility of the surface of the concrete structure 1 even after the peeling prevention sheet 2 is adhered to the surface of the concrete structure 1.

[0100] As a result, the anti-falling construction method can further improve work efficiency and also makes it easier to inspect the concrete structure 1 even after the anti-falling sheet 2 has been adhered.

[0101] In the configuration of the present invention and the correspondence with the above-mentioned embodiment, The mixing step of this invention corresponds to step S102 of the embodiment. Similarly, The coating process corresponds to step S103. The attachment step corresponds to step S104. The degassing process corresponds to step S105. The present invention is not limited to the configurations of the above-described embodiments, and many other embodiments can be obtained.

[0102] For example, in the above embodiment, a concrete tunnel was described as the concrete structure 1, but this is not limited to this, and the concrete structure may be any structure made of concrete, such as a building, a box culvert, a road or a walkway, a bridge pier, or a bridge girder. Further, the top surface 1a and the haunch portion 1b of the concrete structure 1 are described as the construction areas, but the present invention is not limited to this, and any suitable surface of the concrete structure 1 may be the construction area.

[0103] Further, the peeling prevention sheet 2 has a biaxial mesh shape, but is not limited thereto, and may be a peeling prevention sheet formed by coating a mesh sheet having a triaxial mesh shape with a transparent acrylic resin. For example, as shown in Figure 8, which shows a front view of mesh sheet 23 in another embodiment, mesh sheet 23 may be formed in a triaxial mesh shape with a plurality of first linear fiber materials 23a arranged horizontally, a plurality of second linear fiber materials 23b arranged crossing the first linear fiber materials 23a, and a plurality of third linear fiber materials 23c arranged perpendicular to the second linear fiber materials 23b.

[0104] In addition, the mesh sheet 21 is formed from a linear fiber material made of polypropylene, but the present invention is not limited to this, and the mesh sheet may be formed from any suitable linear fiber material. For example, the mesh sheet may be formed from a linear fiber material made of polyethylene terephthalate, or a linear fiber material in which multiple resin fibers are coated with a synthetic resin. Further, the peeling-prevention sheet 2 is in a sheet-like shape, but is not limited thereto, and may be a film-like peeling-prevention sheet or a thin plate-like peeling-prevention sheet.

[0105] In addition, in the surface preparation step (step S101 in FIG. 4), the surface of the concrete structure 1 is impregnated with a primer, but this is not limited thereto, and depending on the condition of the surface of the concrete structure 1, it may not be necessary to impregnate the surface with a primer.

[0106] In addition, the anti-peeling sheet 2 is attached to the concrete structure 1 to which the epoxy resin-based adhesive 4 has been applied, but this is not limited to this, and the anti-peeling sheet 2 to which the epoxy resin-based adhesive 4 has been applied may also be attached to the concrete structure 1.

[0107] Even in this case, the peeling prevention method can prevent the epoxy resin adhesive 4 from dripping from the peeling prevention sheet 2. Therefore, the peeling prevention method can ensure both the safety of the work and the ease of bonding the peeling prevention sheet 2, similar to the above-mentioned embodiment. [Explanation of symbols]

[0108] 1. Concrete structure 2. Anti-peeling sheet 4…Epoxy resin adhesive

Claims

1. A spalling prevention method for reinforcing a surface of a concrete structure by adhering a spalling prevention sheet to the surface of the concrete structure, a mixing process for producing an epoxy resin adhesive by mixing a solid base agent, which has a higher viscosity than a liquid base agent and is determined not to be liquid at temperatures between 20°C and 40°C in the liquid state confirmation of the Fire Service Act Hazard Confirmation Test (Chapter 3 Other Confirmation Methods), with a solid hardener, which has a higher viscosity than a liquid hardener and is determined not to be liquid at temperatures between 20°C and 40°C in the liquid state confirmation of the Fire Service Act Hazard Confirmation Test (Chapter 3 Other Confirmation Methods); a coating step of coating the epoxy resin adhesive on the surface of the concrete structure or on the anti-exfoliation sheet; A sticking step of sticking the anti-falling sheet to the surface of the concrete structure is carried out; The base agent is Contains 5% to 10% of an additive for adjusting viscosity, The curing agent is Contains 5% to 10% of additives to adjust viscosity Spalling prevention method.

2. A defoaming step is performed in which the anti-fall-off sheet attached to the surface of the concrete structure is pressed to remove air bubbles. The peeling prevention method according to claim 1.

3. The base agent and the curing agent each have a flash point of 40° C. or higher. The peeling prevention method according to claim 1 or 2.

4. The anti-peeling sheet is The sheet is made of a coarse mesh sheet coated with a transparent resin, and has transparency and flexibility. The additive of the base material and the additive of the curing agent are amorphous silica. The peeling prevention method according to any one of claims 1 to 3.

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