JPH03224966A - Method of reinforcing concrete structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for reinforcing existing structures made of concrete.

[Prior Art] Some existing structures may require seismic reinforcement because they were constructed according to old design standards and guidelines and therefore have inferior seismic performance compared to structures based on current standards. In addition, it is often necessary to reinforce existing structures, such as when reinforcement is required to meet the design load due to reasons such as increasing the number of building floors when extending or renovating a structure.

Conventional reinforcement methods include surrounding existing column members with steel plates, or enclosing existing column members with welded wire mesh or reinforcing cages, mainly to improve the toughness of the column members, that is, to prevent damage such as cracks. Reinforcement methods have also been proposed that are intended not to reduce the loading capacity and energy consumption capacity.

However, these reinforcement methods require welding of steel plates and the like at the construction site, and welding requires reliable work by highly skilled workers. In addition, it is difficult to transport steel plates into existing buildings because it requires the use of heavy machinery, and cutting them into sizes that can be transported manually increases the amount of welding required at the construction site. It is necessary to inject mortar etc. between the existing column members and the steel plates, welded wire mesh, and reinforcing bar cages to transmit stress, but there are various problems such as it is not easy to fill the mortar etc. densely. have.

Furthermore, the above reinforcement methods generally only increase the shear strength of the existing column members, and in order to maintain the bending strength to the same level as before reinforcement, it is necessary to provide slits in the reinforcement members such as steel plates. . However, if a slit is provided in the reinforcing member located on the outer surface, this part will not be well protected from rain, and as a result, water leakage will be more likely to occur. Another problem is that the steel plate needs to be treated to prevent rust, which increases maintenance and management costs.

Methods of reinforcing bending strength by attaching steel plates to concrete structures using anchor bolts and adhesives or grouting materials have also been proposed, but these methods are not necessarily satisfactory in terms of both reinforcement cost and reinforcement work period.

A reinforcing method has also been proposed in which high-strength fibers are attached in the form of fiber-reinforced plastics using an adhesive. However, the construction method using fiber-reinforced plastics requires the construction method of pasting the fiber-reinforced plastics manufactured in advance at the construction site, and if the reinforcement target is large, it must be divided into small pieces and constructed. Furthermore, there is a problem in that construction becomes complicated depending on the shape of the object to be reinforced.

[Problems to be Solved by the Invention] The present invention solves the problems of the conventional reinforcing methods described above, and provides effective reinforcement for structural elements such as columns, beams, and floorboards of concrete structures. To provide a reinforcing method in which the reinforcing work is easy.

[Means for Solving the Problems] The present invention involves attaching at least one sheet of uncured long fiber prepreg to the surface of a structural element to be reinforced in a concrete structure via a room temperature curing adhesive. A method for reinforcing a concrete structure is provided.

The uncured long fiber prepreg used in the present invention may be one in which reinforcing fibers such as glass fibers or carbon fibers are arranged uniaxially or biaxially, knitted, woven, or randomly arranged. 7 Tricks is impregnated with thermosetting resin such as phenol resin, epoxy resin, unsaturated polyester resin, diallyl phthalate resin, bismaleimide resin, polyimide, polyamideimide, polyurethane resin, etc., and made into a plate shape with a thickness of about 01 to 2 mm. 13 = Tachino. As the prepreg, a high temperature curing type prepreg having a curing temperature of 70° C. or higher is preferably used. This is a lick that prevents the progress of hardening at room temperature and improves storage stability.

As long fibers, glass fibers, carbon fibers, vinylon fibers, aramid fibers, silicon carbide fibers, boron fibers, ceramic fibers, metal fibers, nylon fibers, polyester fibers, etc. are used. Types of long fibers and thermosetting resins are:
They may be appropriately selected depending on the application, and two or more of these may be used in combination.

As the long fiber prepreg, one with high strength and high elasticity is preferably used because it has a large effect of preventing deformation when reinforcing concrete structures.

Room temperature curing adhesive used in the present invention, preferably 10 to
As the adhesive that hardens at 40°C, any commonly used adhesive can be used. for example,
It is an adhesive that uses urea resin, resorcinol resin, phenol resin, epoxy resin, etc. as a base and mixes a curing agent with it so that it can be cured at room temperature. Particularly preferred adhesives include bisphenol A type epoxy resin based adhesives;
An example is one in which an amine curing agent is mixed therein.

As the base material, it is also preferable to select a resin similar to the synthetic resin that forms the matrix of the long fiber prepreg to be used, in order to achieve integrity with the long fiber prepreg and the room temperature curing adhesive.

These room-temperature curing adhesives that cure at a temperature of 10 to 40°C have a centivoise of 6,000 centivoise or less at 23°C, preferably 10
It is preferable to prepare an adhesive solution having a viscosity of 0 to 4000 centivoise, and the solvent used may be any type of solvent as long as the base material such as epoxy resin is soluble therein. Examples include thinner, methyl ethyl ketone, and acetone. If the viscosity of the adhesive solution exceeds the upper limit of the above range, it is undesirable because the solution becomes too hard, making coating work difficult, and the adhesive solution does not penetrate sufficiently into the prepreg. In order to obtain the above-mentioned predetermined viscosity, the base content must be 10% of the solvent.
0 parts to 300 parts of base, preferably 30 to 100 parts
It is best to mix it in parts. Further, it is preferable that such an adhesive solution is applied immediately before or within one hour of applying the prepreg. Although various commonly known coating methods can be employed as the coating method, a method using impregnation is particularly preferred.

The amount of adhesive solution applied is 10 to 200 g, preferably 20 to 100 g per 1 m 2 of prepreg.

By bringing a room temperature curing adhesive into contact with uncured long fiber prepreg, the present invention accelerates the curing of long fiber prepreg, which takes time to cure at room temperature, and develops strength for reinforcement in a relatively short time. can contribute to

Further, since the present invention uses long fiber prepreg, it is lighter than reinforcement using steel plates or the like, and an increase in weight can be prevented.

[Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

Figure 1 is an overview of a reinforced concrete chimney with long fiber prepreg attached by the method of the present invention, Figure 2 is an overview of a case where high-strength long fiber strands are further wound, and Figure 3 is an overview of long fiber prepreg applied to a reinforced concrete chimney by the method of the present invention. FIG. 2 is an enlarged cross-sectional view of a reinforced portion in which three layers of prepreg are attached.

The present invention will be explained in detail below based on FIG.

A permeable primer 6 is applied to the outer surface of the reinforced concrete 1 to chimney 1 in order to have good affinity with the adhesive.

As the penetrating primer, the same type as the adhesive is preferably used to improve affinity. After the permeable primer 6 is cured, a room temperature curing adhesive 7 is applied.

It is preferable to use the room temperature curing adhesive after diluting it with thinner as appropriate to improve workability.

Immediately after applying the room temperature curing adhesive 7, the first layer of long fiber prepreg 3 is attached. When the long fiber prepreg is one in which the long fibers are arranged in a uniaxial direction, it is preferable to attach the long fibers so that the direction in which the long fibers are arranged coincides with the long axis direction of the chimney in order to exert a strength reinforcing effect.

After pasting the long fiber prepreg 3, room temperature curing adhesive 7
was applied to the surface of the long fiber prepreg 3, and then the second layer of long fiber prepreg 4 was applied in the same manner as the first layer of long fiber prepreg 3, and then the room temperature curing adhesive 7 was applied. do. Thereafter, the third layer of long fiber prepreg 5 is pasted in the same manner. Preferably, a room temperature curing adhesive 7 is then applied.

The reinforcement work according to the method of the present invention is completed when the room temperature curing adhesive 7 is cured.

The explanation based on FIG. 3 above is based on the case where three layers of long fiber prepreg are laminated, but the number of layers is appropriately selected depending on the required amount of reinforcement and the strength per sheet of long fiber prepreg.

FIG. 2 shows a case where a high-strength long fiber strand 8 is further wound around the long fiber prepreg attached to the chimney shown in FIG. When winding the high-strength long fiber strand 8, an edge cut is applied to the surface of the uppermost layer of the cold-curing adhesive 7 to prevent adhesion between the cold-curing adhesive layer and the wound layer of the high-strength long fiber strand. It is preferable to cover the material with a synthetic resin film, such as a polyester film, and wind the high-strength long fiber strand 8 on top of this film. At this time, the high-strength long fiber strand 8 is wound while being impregnated with resin, but a resin that does not adhere to the edge cutting material or has low adhesive strength is used as the resin. As a result, the wound layer of the high-strength long fiber strand 8 is maintained in a state where it is separated from the uppermost room-temperature curing adhesive layer 7.

The long fibers used for the high strength long fiber strand 8 are as follows:
Glass fiber, carbon fiber, vinylon fiber, aramid fiber,
Silicon carbide fibers, boron fibers, ceramic fibers, metal fibers, nylon fibers, polyester fibers, etc. are used.

Two or more of these fibers may be used in combination. The number of ficimen of the fibers is appropriately selected depending on the required strength.

As the edge trimming material, it is recommended to select a material that does not adhere to the fiber-reinforced resin or has low adhesive strength, such as the polyester film \ mentioned above, since it is recommended to select a material that does not adhere to the fiber-reinforced resin or has a low adhesive strength. This is preferable for achieving a break with the people.

After the top layer of the room-temperature curing adhesive is completely cured, the high-strength long fiber strand 8 is wound, and the high-strength long fiber strand 8 is coated with a resin that has low adhesive strength with the top layer of the room-temperature curing adhesive. By impregnating it, the edge cutting material may be omitted. Furthermore, instead of the synthetic resin film, an oil-based paint or the like may be applied to the uppermost cold-setting adhesive layer as the edge cutting material.

There is no need to cut the edge between the uppermost room temperature curing adhesive layer and the high-strength long fiber strand winding layer; in this case,
There is no need to impose the above-mentioned restrictions on the type of reinforcing resin impregnated into the high-strength long fiber strand.

[Effects of the Invention] According to the method of the present invention, the uncured long fiber prepreg can be attached while sufficiently following the unevenness of the concrete surface, and stress transmission from the concrete structure is also facilitated. , a reinforcing method that fully utilizes the strength of long fibers as a reinforcing material is provided.

According to the method of the present invention, there is provided a reinforcing method that can easily provide sufficient reinforcement even if the surface of a component of a concrete structure has a complicated shape such as a curved surface.

According to the method of the present invention, by using an uncured long fiber prepreg and a room temperature curing adhesive, special processes such as heat curing are not required, and reinforcement curing can be achieved in a short time. A reinforcing method is provided.

Furthermore, according to the method of the present invention, by using long fibers with high specific strength as a reinforcing material, it is possible to significantly reduce the weight increase due to reinforcement. A method is provided.

Furthermore, according to the method of the present invention, since the reinforcing material is lightweight, it can be transported without using a lifting machine or the like, and a reinforcing method is provided which makes the pasting work simple and easy.

[Brief explanation of drawings]

Figure 1 is an overview of a case where long fiber prepreg is laminated on a reinforced concrete chimney, Figure 2 is an overview of a case where high-strength long fiber strands are further wound, and Figure 3 is an enlarged cross-sectional view of the reinforced part. . 2: Long fiber prepreg 3: First layer long fiber prepreg 4: Second layer long fiber prepreg 5: Third layer long fiber prepreg 7: Room temperature curing adhesive

Claims (1)

[Claims] on the surface of structural elements that are to be reinforced in concrete structures,
A method for reinforcing a concrete structure, which comprises attaching at least one sheet of uncured long fiber prepreg via a room temperature curing adhesive.