JPH08218646A - Method of reinforcing concrete structure - Google Patents

Abstract

PURPOSE: To reinforce a concrete column against both shearing and bending, by winding a tape composed of high strength fibers around the concrete structure after a primer applied to the concrete structure which are mended at broken parts in the outer surface of the concrete structure is cured, and by applying an adhesive thereto. CONSTITUTION: After cleaning a columnar concrete structure 5 having been mended by removing broken parts in the outer surface thereof, an epoxy resin primer is applied over the outer surface of the concrete structure, and is cured, and then, an epoxy resin adhesive is evenly applied thereover. Thereafter, a tape 1 in which high strength fibers are plainwoven is continuously wound around the structure, being bonded thereto. Flexible fibers such as aromatic polyamide fibers used as longitudinal fibers of the tape 1, and high strength fibers such as carbon fibers used as widthwise fibers of the tape 1, are woven together, linear interfiber gaps being defined thereamong. Then, the tape is wound around the column, and thereafter, an adhesive is applied to the tape so as to integrally incorporate the tape with the column which is therefore reinforced against both shearing and bending. Thereby it is possible to enhance the workability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforcing method using a reinforcing tape for reinforcing an existing concrete structure.

[0002]

2. Description of the Related Art Conventionally, the strength of existing concrete buildings, concrete chimneys, concrete structures such as bridge piers, etc. decreases due to cracks and deterioration of concrete due to components in the atmosphere. A steel material such as an iron plate is provided by winding, and mortar or resin is injected between the structure and the steel material to reinforce it. However, in this method, the weight of the steel material increases the weight of the structure itself, and there is a drawback in that the work becomes large. To solve these drawbacks, for example, Japanese Patent Publication No. 5-
As disclosed in Japanese Patent No. 73863, it is possible by winding a high-strength long-fiber strand around an existing column and adhering the strand to the column with an adhesive to reinforce the column if necessary. Further, Japanese Patent Application Laid-Open No. 4-89970 also proposes a method in which a textile impregnated with a curing agent is wrapped around a column or the like and the curing agent is cured to reinforce the textile.

[0003]

Carbon fibers, glass fibers, and aromatic polyamide fibers are used for the high-strength long fiber strands. For example, the carbon fiber monofilaments have a diameter of 12 μm, and 6000 of them are used. Even if bundled, the thickness is about 0.5 mm, and in order to tightly wind this around the pillar, it is necessary to wind 300 times per 1 m of the pillar length, and the winding work is difficult by hand. The work efficiency cannot be improved without using a special machine.
Also, with the method of winding a textile impregnated with the above-mentioned curing agent, the number of times of winding can be reduced because the textile can be made relatively wide, but there is no description about the composition and material of the textile, and the textile is impregnated with the curing agent. The work of wrapping and winding a long textile that has been impregnated with a curing agent is quite troublesome, and this method does not take into consideration the transmission of force due to the adhesive force between the column and the textile, and it is used for shear reinforcement of the column. Is not enough.

Carbon fiber is currently the most suitable fiber for use in such wrapping reinforcement from the viewpoint of tensile strength, but since this fiber has the drawback of being inflexible and easily broken, it has corners. It is not suitable for reinforcement of concrete structures, and its versatility is poor because its use is limited to reinforcement of structures such as cylinders. Further, in the case of a structure that bears an axial load such as a reinforced concrete column, there is a drawback that the winding of the strand can reinforce the shearing force but cannot reinforce the bending of the structure.

The present invention provides a simple reinforcing method using a reinforcing tape which can reinforce an existing concrete structure without being restricted by its cross-sectional shape, and reinforces both shearing and bending of the concrete structure. The purpose of the present invention is to provide a reinforcing method.

[0006]

According to the present invention, a damaged portion of the surface of a columnar concrete structure is removed and repaired to clean it, and then a primer is applied to the surface to cure it and adhered to the surface. After applying the agent evenly, use chemical fibers with greater tensile strength and flexibility than concrete for the fibers in the length direction of the tape, and position the fibers in the length direction in the fibers in the width direction. A fiber for using a fixable chemical fiber, weaving the chemical fiber in the length direction in a linear array with the fiber in the width direction, and positively distributing an adhesive between the front and back of the tape. The above-mentioned object was achieved by winding and adhering a concrete structure reinforcing tape woven and woven with a space around the columnar concrete structure so as not to loosen. Use of a chemical fiber having a tensile strength higher than that of concrete and a tensile modulus higher than that of the lengthwise fiber as the widthwise fiber achieves the purpose of easily reinforcing both shearing and bending of the concrete structure. it can. Further, the above object can be more appropriately achieved by the method according to claims 2, 4, 5, and 6.

[0007]

Since the reinforcing tape is flexible in the lengthwise direction, it can be wound around the corners of the concrete structure without slack, and the primer is applied to the surface of the structure where the damage is repaired. Since the tape is adhered by the adhesive applied after being cured, the adhesive surface is flat and the adhesiveness with the tape is good, and the adhesive passes through the fiber space positively formed on the tape. It penetrates securely into its interior and the tape adheres firmly to the surface of the structure after the adhesive has hardened. Therefore, the shearing force generated in the structure can be surely transmitted to the tape, and the tape having a higher tensile strength than concrete can reliably withstand the shearing force generated in the structure.

As the widthwise fibers of the reinforcing tape, when chemical fibers such as carbon fibers having a higher tensile strength than concrete and a higher tensile elastic modulus than the lengthwise fibers are used, the surface of the structure is When the edges of the tape are overlapped and wound and adhered, the fibers in the width direction are continuous by the adhesive in the axial direction of the structure, that is, in the direction orthogonal to the winding direction, and in this state. The bending stress generated in the structure can be supported by the continuous fibers in the width direction. If the adhesive is applied again from above the wound tape, the amount of the adhesive impregnated into the tape is increased and the adhesiveness with the structure is improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the attached drawing. In FIG. 1, reference numeral 1 is a concrete structure reinforcing tape made by plain weave knitting. As the fibers 2 in the length direction of the tape 1, chemical fibers having a higher tensile strength and higher flexibility than concrete are used, and the fibers 3 in the width direction are represented by, for example, glass fiber or nylon (trade name). Chemical fibers are used, such as fibers, which can fix the position of the fibers along the length. These fibers 2 and 3 are knitted into a plain weave in a state in which the chemical fibers 2 in the lengthwise direction are linearly arranged by a known loom as shown in the schematic view of FIG. The tape 1 is knitted and woven with a fiber space 4 for positively flowing the adhesive between the front and back sides of the tape 1. As shown in FIG. 3, the tape 1 is wound and adhered to reinforce the columns and beams of the concrete structure 5.

Since the tensile strength of concrete is about 15 kgf / cm ² , an aromatic polyamide fiber having a tensile strength of 15000 to 20000 kgf / cm ² and flexibility is suitable as the fiber 2 in the length direction. Fibers having a higher tensile strength than concrete include, in addition to aromatic polyamide fibers, inorganic fibers such as carbon fibers, glass fibers, and ceramic fibers, and organic fibers such as polyester fibers, high-strength polyolefin fibers, and high-strength polyvinyl alcohol fibers. It is known that inorganic fibers are easily broken and lack flexibility, and these organic fibers also have some flexibility,
It cannot be bent at a right angle like aromatic polyamide fibers. The fibers 2 in the longitudinal direction, when wound, are shown in FIG.
It may be bent at the corners of the column like this, and flexibility is required so that it will not break at this time. Further, considering that heat resistance of about 60 ° C. is required from the viewpoint of use environment, the above aromatic polyamide fiber is currently the most suitable.

On the other hand, the fibers 3 in the width direction rarely undergo abrupt bending even when wound, so that flexibility is not an essential condition, and the arrangement of the fibers 2 in the length direction is maintained and the use condition. Accordingly, in order to reinforce the bending strength of the concrete structure, a fiber having a tensile strength and a tensile elastic modulus larger than that of the fiber 2 in the longitudinal direction is used. Although glass fiber is suitable for the widthwise fiber 3 in consideration of price, it is also effective to use carbon fiber having extremely high tensile strength although it is expensive. When it is adhered to a concrete structure by means of, for example, carbon fibers are adhered in a direction intersecting the winding direction with an adhesive as shown in FIG. 5 to be continuous, and the bending strength of the structure can be reinforced.

When the fibers 2 and 3 are knitted into a plain weave structure, a fiber space 4 is formed. The size of the fiber space 4 is a substantially rectangular space in which the adhesive can flow, for example, about 0.5 to 3 mm. And its size is determined in consideration of the viscosity of the adhesive. The space does not have to be formed perpendicularly to the surface of the tape 1, and its size can be adjusted by adjusting the number of yarns composed of the fibers 2 and 3.

The reinforcing tape 1 is wound around a columnar concrete structure 5 such as a concrete column or a beam as shown in FIG. 3 to be used for reinforcement thereof.
As described above, the structure 5 is cleaned by removing and repairing the damaged portion such as dirt and cracks on the surface, and the primer is applied to the surface also for the purpose of repairing the surface, and this is cured. Then, after uniformly applying an adhesive to the surface, the reinforcing tape 1 of the present invention is wound so as not to loosen. In this case, the edges 6 of the tape are laminated and attached so that the fibers 3 in the width direction of each loop of the wound tape 1 are continuous. As a result, the adhesive is impregnated into the inside of the tape 1 through the fiber space 4 of the tape 1 and flows to the back surface side, and after curing, the entire tape 1 firmly adheres to the structure 5. As the primer, it is preferable to use a primer having a specific gravity of about 1 which exhibits an adhesive strength of 10 kgf / cm ² or more after 7 days at 20 ° C.
An epoxy-based primer having a composition of 20% by weight, 25% by weight of a solvent, 24% by weight of a modified heterocyclic diamine as a curing agent, 2% by weight of a tertiary amine, and 24% by weight of a solvent.
A primer is used which exhibits an adhesive strength of 20 kgf / cm ² after 7 days at 0 ° C. Also, as the adhesive,
Tensile shear strength, compressive yield strength and compressive elastic modulus after 7 days are 100 kgf / cm ² or more and 500 kgf / cm ² or more, 10 respectively.
For example, an epoxy resin adhesive having a value of 000 kgf / cm ² or more is used. If an epoxy resin adhesive having this value and having a viscosity of 1000 cm Pois is applied to the outer surface of the tape 1, the fiber space 4 of the tape 1 is 0.5 mm ×
Even if it is 0.5 mm, it penetrates into the inside and the back surface sufficiently, and after hardening, the tape 1 becomes integral with the concrete.

When the adhesive is applied to the surface of the tape 1 again after the sticking is completed, the tape and the structure are more surely adhered.

After the adhesive applied to the tape 1 is cured, a suitable paint is applied to the outer surface of the tape 1 in order to protect the tape 1 from ultraviolet rays and ozone and improve weather resistance, durability and aesthetics. In order to protect the tape 1 from fire and external damage depending on the use environment, it is finished with cement or mortar or by installing an exterior plate. A special machine is not particularly required for this winding work, and it can be performed relatively quickly by hand.

In a specific embodiment, the longitudinal fibers 2
6000 denier aromatic polyamide fiber 0.5 mm in diameter is used per 1 cm 7 as the width direction fiber 3 6000 denier glass fiber diameter 0.5
The width is 75 by the loom using 3 mm yarns per cm.
A ± 5 mm plain weave reinforcing tape 1 was prepared. A rectangular fiber space 4 of 0.5 to 1 mm is formed between the yarns.
The cross-sectional area of this tape 1 is 0.345 cm ² , the tensile modulus in the length direction is 0.6 × 10 ⁶ kg / cm ² , and the tensile strength is 15
It was 000 kg / cm ² . On the other hand, the surface of a concrete column with a square cross section that requires reinforcement and has a length of 5 m and a side width of 60 cm is removed and repaired to clean it, and when the water content of the surface is 8%, 20 ° C, 7 After the application of an epoxy-based primer that exhibits an adhesive strength of 20 kgf / cm ² , after curing, an epoxy resin adhesive with a viscosity of 1000 cm Pois that satisfies the above values is applied, and the pitch interval is 7.5 cm, that is, the overlapping width is 0 mm. The tape 1 was wound without looseness.
After the winding is completed, the adhesive is applied from the outer surface of the tape 1 so that the tape penetrates into the fiber space 4, and the periphery thereof is covered with a vinyl sheet so as not to directly touch the reinforcing surface of the structure and cured for 2 weeks. It was The average temperature during this period was 20 ° C. Shear strength of the concrete column before reinforcement is 20kgf / cm
It was ² , but as a result of this reinforcement, the shear strength was 30 kgf / cm.
Improved to ² . The time required for winding the tape 1 was 3 hours as a total time of 2 workers.

In place of the reinforcing tape 1 described above, seven fibers having a diameter of 0.5 mm of 300,000 denier aromatic polyamide fibers are used as the fibers 2 in the lengthwise direction, and 6,000 denier as the fibers 3 in the widthwise direction. A plain weave reinforcing tape 1 having a width of 300 ± 5 mm is prepared by a loom using 3 carbon fibers having a diameter of 0.5 mm per cm, and the pitch interval is 20 cm, that is, the overlapping width is 10 cm. Reinforcing work was performed in the same manner except that
The overlap margin (overlap width) L (mm) is L = F / τ, where F is the tensile strength of the tape per 1 cm width (kg / cm 2), and τ is the permissible shear strength of the resin (kg / cm ² ). Was calculated. In this case, F = 300, τ = 30, and L is 10 mm. As a result of this reinforcement, the carbon fibers in the width direction are continuously adhered to the surface of the concrete column in the length direction, the shear strength thereof is improved to 30 kgf / cm ² , and the bending strength is also 120 k.
Improved to g / cm ² .

Considering the finished state after winding, it is preferable to wind the tape 1 without overlapping it, but if there is no overlap margin, the fibers 3 in the width direction are not continuous in the length direction of the column, so that the bending strength is reinforced. The ability was decreased, and in the former specific example, the shear strength could be reinforced to the above values, but the bending strength was not reinforced.

[0019]

As described above, in the present invention, after the surface of a columnar concrete structure is restored and cleaned, a primer is applied and cured, and an adhesive is evenly applied to the surface. The longitudinal fibers on the surface are chemical fibers having higher tensile strength and better flexibility than concrete, and the widthwise fibers are chemical fibers capable of fixing the position of the longitudinal fibers, A concrete structure in which chemical fibers in the length direction are linearly arranged together with the fibers in the width direction and knitted with a fiber space for positively flowing an adhesive between the front and back of the tape. Since the reinforcing tape is wound and adhered to the structure so as not to be loosened, the tape can be sufficiently integrated and adhered to the structure, and the shearing force generated in the structure can be surely applied to the tape. Can be communicated to The structure can be reinforced by the tape, the structure can be reinforced without being restricted by the cross-sectional shape of the structure, and the work can be easily performed without using a special machine. Also, by using a chemical fiber having a high tensile strength and a tensile modulus higher than that of the fiber in the length direction, both shearing and bending of the structure can be reinforced at the same time, and it is possible to reinforce a special structure. It is advantageous and has the effect of improving workability.

[Brief description of drawings]

FIG. 1 is a perspective view of a reinforcing tape used in the present invention.

FIG. 2 is an enlarged plan view of a main part of the reinforcing tape used in the present invention.

FIG. 3 is a perspective view of an embodiment of the reinforcing method of the present invention.

FIG. 4 is an explanatory view of one step of the reinforcing method of the present invention.

5 is an enlarged cross-sectional view of the main part of FIG.

[Explanation of symbols]

1 Concrete structure reinforcing tape 2 Fiber in length direction 3 Fiber in width direction 4 Fiber space 5 Concrete structure 6 Edge part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Eguchi 1-12-20, Uemachi, Ageo City, Saitama Kobayashi Heights 105

Claims (6)

[Claims] 1. After removing and repairing a damaged portion of the surface of a columnar concrete structure to clean it, a primer is applied to the surface to cure it, and an adhesive is evenly applied to the surface, The fibers in the length direction of the tape are made of chemical fibers having higher tensile strength and flexibility than that of concrete, and the fibers in the width direction of the tape are used to fix the position of the fibers in the length direction. Concrete woven together with the fibers in the width direction in a state where the chemical fibers in the length direction are linearly arranged and having a fiber space between the front and back sides of the tape for positively flowing an adhesive. A method for reinforcing a concrete structure, comprising winding a structure reinforcing tape around the columnar concrete structure so as to prevent the tape from being loosened and adhering the tape. 2. The lengthwise fibers are aromatic polyamide fibers or carbon fibers, the widthwise fibers are fibers represented by glass fibers or nylon (trade name), and the primer is an epoxy resin. 2. The method of reinforcing a concrete structure according to claim 1, wherein the adhesive is an epoxy resin adhesive. 3. After removing and repairing a damaged portion of the surface of a columnar concrete structure to clean it, a primer is applied to the surface to cure the same, and an adhesive is evenly applied to the surface, The fibers in the length direction of the tape are made of chemical fibers that have greater tensile strength and flexibility than concrete, and the fibers in the width direction have greater tensile strength than concrete and more tensile elasticity than the fibers in the length direction. A concrete structure in which chemical fibers having a high rate are used, and the reinforcing tape is knitted together with the fibers in the width direction in a state where the chemical fibers in the length direction are linearly arranged. A method for reinforcing a concrete structure, which comprises winding and adhering to a concrete structure. 4. The lengthwise fibers are aromatic polyamide fibers, the widthwise fibers are carbon fibers, the primer is an epoxy resin primer, and the adhesive is an epoxy resin adhesive. The concrete structure reinforcing method according to claim 3, wherein 5. The concrete structure reinforcing tape according to claim 1, wherein the tape is wound around the concrete structure so that the width direction fibers of each loop are continuous and the edges are overlapped. Reinforcement method for concrete structures. 6. The tape for reinforcing a concrete structure is wound and adhered to the columnar concrete structure so as not to loosen, and an adhesive is further applied onto the tape. Alternatively, the method for reinforcing a concrete structure according to Item 3.