Method of repairing cracks in concrete structure

Abstract

To waterproof cracks that occur in concrete structures by filling gaps in torn areas and subsequent deep cracks with sufficient repair material, and to strongly connect the torn areas and deep cracks.SOLUTION: A repair material used in this invention is a room-temperature reaction type liquid acrylic resin made by mixing low-viscosity agent A and agent B shown in Figure 3 at a predetermined weight ratio concentration. A roller used here has a tube diameter of substantially 16 to 26 mm, attached with roller bristles made of wool or acrylic bristles or sponge with a diameter of substantially 8 to 13 mm. The repair material is poured in and hardened evenly by applying pressure to the torn area while rotating the roller as shown in Figure 1.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] This invention relates to a method for repairing cracks that occur on the surface of a concrete structure, and is a method for repairing cracks that can be used regardless of the width and length of the crack's break on the surface of the crack. This relates to a repair method that thoroughly fills narrow gaps in the concrete following the crack break with repair material to close the gap and prevent rainwater from entering, and also increases the concrete's connection strength. In addition to providing strength by infiltrating the repair material into the ends of the crack, this repair method also increases the strength by allowing the repair material to seep into the voids (gaps) in the concrete around the crack. [Background technology]

[0002] If a concrete structure has been in use for many years, cracks and fissures will often appear on its surface due to earthquakes, ground vibrations, uneven subsidence of the ground, repeated loads from passing vehicles, the load of the structure itself, or drying shrinkage of the poured concrete. Cracks can occur not only due to external vibrations, loads, and deterioration after concrete has been poured, but also due to the evaporation of moisture during drying immediately after concrete is poured.

[0003] (Current state of microcracks) Currently, microscopic cracks less than 0.2 mm in width (so-called hair cracks) are not subject to investigation under the Ministry of Land, Infrastructure, Transport and Tourism's Guidelines for Civil Engineering Construction Management Standards. On the other hand, the Japan Concrete Industry Association divides crack widths into the following three levels, and instructs that repair methods and materials should be used that are appropriate for each width. The construction method and materials used are as follows: 1. If the crack width is 0.2 mm or less → Surface coating method (sealing method) 2. If the crack width is 0.2 to 1.0 mm, use the injection method. 3. If the crack width is 1.0 mm or more, use filling method For the reasons mentioned above, when it comes to fine cracks (hair cracks) with a width of less than 0.2 mm, the purpose of covering the surface is to prevent deterioration factors from penetrating into the concrete, to prevent staining, and to maintain the aesthetic appearance. However, from the perspective of maintaining the strength after the cracks have been repaired, this method is insufficient because its purpose is to prevent deterioration factors from penetrating by covering the surface.

[0004] As one method for solving this problem, a method has been invented in which carbon fiber sheets are attached to the surface of a concrete structure to maintain or improve the strength of the structure in the event of cracking. This method does indeed maintain or improve the strength of the structure itself, but it does not emphasize filling the cracks with repair materials such as resin. When repairing with this method, problems such as neutralization of concrete and rusting of reinforcing bars caused by the infiltration of rainwater and other water cannot be fully solved.

[0005] Furthermore, Patent Documents 1 and 2 disclose conventional methods for repairing cracks in concrete structures, but the invention in Patent Document 2 involves creating a groove on the fracture surface of the crack, filling the groove with an elastic seal, applying a stripping agent, and then rolling the surface flat with a pressing means.

[0006] This repair method requires time-consuming groove formation work, and uses an elastic sealant that has a weak filling power when penetrating deep gaps in the cracked concrete, so it is considered to have low waterproofing and adhesion effects.

[0007] Furthermore, in the simple repair invention of Patent Document 1, it is considered that the closing force of the fracture surface of the crack and the filling and connection of the deeper parts of the crack are insufficient. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2010-19036 A [Patent Document 2] Patent Publication No. 2022-11875 Summary of the Invention [Problem to be solved by the invention]

[0009] The problem that the present invention aims to solve is to provide a repair method that enables anyone to easily infiltrate repair material deep into cracks, even for very small gaps with a width of less than 0.2 mm, without the need for specialized injection equipment, and that also increases the connecting strength. [Means for solving the problem]

[0010] The configuration of the present invention that solves such problems is as follows: 1) A method of repairing cracks in a concrete structure by impregnating the inside of a paint roller with a low-viscosity repair material, and repeatedly applying pressure to the fracture surface of a crack in a concrete structure or the surface surrounding the fracture surface of the crack with the paint roller impregnated with the low-viscosity repair material, thereby squeezing out the low-viscosity repair material impregnated into the paint roller and causing it to flow out from the fracture surface into the crack voids in the concrete, thereby filling the fracture on the surface of the crack in the concrete body and the voids following the fracture, and solidifying the filled low-viscosity repair material so as to fill the fracture on the surface of the crack in the concrete body and the voids following the fracture, thereby connecting the crack spaces, thereby repairing cracks in a concrete structure. 2) A method for repairing cracks in a concrete structure as described in 1) above, in which a low-viscosity repair material that satisfies the following values ​​in accordance with J13 A 6024 is used as the low-viscosity repair material as described in 1) above. Note Viscosity≫JIS quality standard 100~1000 (mPa·S) Adhesive strength (standard temperature)≫6.0(mPa) Adhesive strength (low temperature, wet (dry))≫3.0(mPa) is located. Effect of the Invention

[0011] Therefore, in this invention, we have developed a low-viscosity resin for repairing cracks, and by impregnating a painting roller with this resin and using it as shown in Figure 2.4, the resin can penetrate deep into the cracks, solving the above problem. In the present invention, a painting roller soaked in a low-viscosity repair resin is used, and the painting roller soaked in the low-viscosity repair material is pressed against the broken part of the crack, and pressure is applied to squeeze out the resin that has soaked into the roller bristles, encouraging the low-viscosity resin liquid to penetrate deep into the crack. By applying pressure, the resin will penetrate deep into the crack due to the capillary effect. It is better to repeatedly apply pressure with the painting roller until the filled resin stops settling.

[0012] Furthermore, with this method, the strength of the area around the repaired part can be maintained by penetrating the low-viscosity repair material deep into the cracks, eliminating the need to apply the repair material to the surface of the structure, as was done in the past. Also, with this low-viscosity repair material, any resin that leaks out from the crack during construction can be easily removed using a solvent or a metal spatula-shaped tool with a handle at the end, making it possible to not only maintain the beauty of the repaired surface, but also to pour more concrete. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is an explanatory diagram showing the state of cracks in concrete. [Diagram 2] FIG. 2 is an explanatory diagram showing the state in which a paint roller impregnated with a low-viscosity repair material of the present invention is rolled onto the fractured portion of the surface of a crack, filling the fractured portion of the crack and its deeper voids. [Diagram 3] FIG. 3 is a component table showing the components of the base agent (agent A) and hardener (agent B) of the low-viscosity repair material made of room temperature reactive liquid acrylic resin in an embodiment of the present invention, as well as their concentrations and concentration ranges (weight percentages). [Figure 4] FIG. 4 is a process diagram showing the construction procedure of this embodiment. [Diagram 5]FIG. 5 is an explanatory diagram showing the state of the low-viscosity repair material filled into the crack after repair and the hardened state of the repair material in the bottom crack. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The viscosity of the low-viscosity repair material of the present invention is preferably 100 to 1000 (mPa·S) according to the JIS quality standard, and the adhesive strength at standard temperature is preferably 6.0 mPa or more. The diameter of the roller body of the painting roller is preferably 16.5 mm to 26 mm depending on the size and length of the crack. The length of the roller bristles is preferably 4.0 mm short bristles to 13.0 mm medium bristles. The roller bristles may be made of wool or acrylic bristles or may be made of sponge.

[0015] Regarding the painting roller to be used with this low-viscosity repair material, it is desirable that the roller body can be removed from the handle of the painting roller so that the roller body can be easily replaced. Regarding the handle of the paint roller, any standard handle sold on the market will do. Regarding the length and material of the roller body, the length of the paint roller ranges from 2 inches to 7 inches, and is used according to the condition of the cracks (1 inch is approximately 2.5 cm). Furthermore, the diameter of the roller body should be 16.5 mm (small size) to 26.0 mm (medium size). The length of the roller bristles on the paint roller should be short (around 8.0 mm) or medium (around 13.0 mm). The bristles can be made of wool, acrylic, or sponge, but basically any standard handle and roller body used for architectural painting will do. EXAMPLES

[0016] An embodiment of the present invention shown in Figures 1, 2, 3, 4 and 5 will be described. This embodiment relates to a method for repairing a crack 10, as shown in FIG. This is a method for repairing a crack 10 shown in Figure 1, in which the width of the fractured portion 11 is 0.3 mm, and a void 12 has developed about 15 mm deep in a concrete structure 1. The low-viscosity repair material 2 uses a room-temperature reactive liquid acrylic resin made by mixing agent A (main agent) and agent B (hardening agent) shown in Figure 3 in a weight mixture ratio (1:1).

[0017] The low-viscosity repair material 2 used is a material with a JIS quality standard of 7.2 mPa and an adhesive strength of 6.0 mPa at standard temperature, and is a room temperature reactive liquid acrylic resin with the following characteristics, kneaded with agent A (main agent) and agent B (hardener) in a 1:1 weight ratio. Note Viscosity≫JIS quality standard 100~1000 (mPa·S) Adhesive strength (standard temperature)≫6.0(mPa) Adhesive strength (low temperature, wet (dry))≫3.0(mPa)

[0018] The roller body 30 of the coating roller 3 has a cylindrical diameter of 16.5 mm, and the roller bristles 32 are made of wool or acrylic and have a length of 4.0 mm.

[0019] The repair work, in which the painting roller 3 is impregnated with the low-viscosity repair material 2, is carried out as shown in the detailed steps in Figure 4. Figures 2(a), (b) and (c) show the painting roller 3 and the squeezing and flowing down of the low-viscosity repair material 2 during this work. Figure 5 shows the penetration and hardening state of the low-viscosity repair material 2 in this embodiment. Figure 5 shows the state of filling into cracks 10 in a concrete structure 1. As can be seen from the α, β and γ states in Figure 5, the low-viscosity repair material 2 is well filled into fractured areas 11 and deep voids 12.

[0020] In the figure, 1 is a concrete structure, 10 is a crack in the concrete structure, 11 is the fracture part of the crack, 12 is a void in a microcrack that has occurred deep in the concrete, 13 is the repair surface of the concrete structure 1, 2 is a low-viscosity repair material, 3 is a painting roller, 30 is the plastic roller body that rotates to apply pressure, 31 is the roller operating shaft, 32 is the roller bristles, and 4 is the hardened repair material that has overflowed from a crack on the back side of the concrete structure and hardened.

[0021] The coating roller 10 is impregnated with the low-viscosity repair material 2, and the coating roller 3 is rotated under pressure while being pressed against the rupture 11 of the crack 10 in Figures 1 and 2, so that the low-viscosity repair material 2 impregnated in the coating roller 3 is extracted from the rupture 11 as if being squeezed out, and sent into the gaps in the crack 10. Since the low-viscosity repair material 2 has low viscosity, it easily flows into the crack 10 in the rupture 11, and is sent into the gaps 12 in the crack deep inside. The coating roller 3 on the rupture 11 applies pressure to squeeze out the low-viscosity repair material 2 into the rupture 11, and pressurizes the squeezed low-viscosity repair material 2 from above to force it into the deep gaps 12 in the crack 10.

[0022] As a result, as shown in FIG. 5, the expanded crack 10 in the fractured portion 11 is sufficiently pressurized and filled, and the material is also fed into a narrow gap, reliably filling the gap 12 and joining the gap. In Figure 5, α indicates the main repair material filling state filled in the main crack space of crack 10, β in Figure 5 indicates the repair material layer that has penetrated into the fine gaps that occur on the opposing inner surfaces of crack 10, and γ in Figure 5 indicates the filling state of the repair material at the crack end that has penetrated into the fine gaps at the deep end of crack 10. As a result, the voids 12 in the cracks 10 in the concrete structure 1 are well filled, and the connection strength is also high. [Industrial Applicability]

[0023] The present invention is capable of repairing not only concrete structures, but other concrete products as well. [Explanation of symbols]

[0024] 1. Concrete Structures 10. Crack 11 Crack fracture 12. Deep crack voids 13 Repair surface of cracked concrete structure 2. Low-viscosity repair material 21 Repair material puddle 3 Paint roller 30 Roller body 31 Roller operating shaft 32 Roller hair 4 Repair material hardening

Claims

1. A method for repairing cracks in a concrete structure by impregnating the inside of a paint roller with a low-viscosity repair material, and repeatedly applying pressure to the fracture surface of a crack in a concrete structure with the paint roller impregnated with the low-viscosity repair material on the surface of the fracture surface of a crack in the concrete structure or on the surface surrounding the fracture surface, thereby squeezing out the low-viscosity repair material impregnated into the paint roller and causing it to flow from the fracture surface into the crack voids in the concrete, filling the fracture on the surface of the crack in the concrete body and the crack void spaces adjacent to the fracture, and solidifying the filled low-viscosity repair material so as to fill the fracture on the surface of the crack in the concrete body and the voids adjacent to the fracture and connect the crack spaces.

2. A method for repairing cracks in a concrete structure according to claim 1, wherein a low-viscosity repair material that satisfies the following values ​​in accordance with J13 A 6024 is used as the low-viscosity repair material of claim 1. Note Viscosity≫JIS quality standard 100-1000 (mPa・S) Adhesive strength (standard temperature)≫6.0 (mPa) Adhesive strength (low temperature, wet (dry))≫3.0 (mPa)

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