JP2000248689A - Reinforcing material and reinforcing construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reinforcing material and a reinforcing construction method capable of improving workability and shortening the term of works by reducing the amount of thermosetting resin to be used. SOLUTION: A reinforcing material is obtained from prepreg obtained by impregnating a thermosetting resin to a reinforcing sheet 20 woven with a conductive tape or conductor 4 as weft 2 to a reinforcing sheet 10 or to a reinforcing sheet 10 woven with a conductive tape or conductor 3 as a warp 1 to one-way sheet 10 comprising practically the aramid fiber for warp 1, and this reinforcing material is wound around a structure. Then, a current is applied to the conductive tape or a conductors 3, 4 for heating thereby hardening the resin and reinforcing the structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforcing material, and more particularly, to a reinforcing material comprising a prepreg used in a method of winding around an existing concrete column or the like, hardening an impregnated resin, and strengthening against earthquake, and a reinforcing method. is there.

[0002]

2. Description of the Related Art Conventionally, a seismic retrofitting method using carbon fiber or aramid fiber is to prepare a unidirectional sheet of such fiber, wind it around an existing structure such as a concrete column requiring reinforcement, and cure at room temperature. A method of applying and impregnating a resin and leaving it to cure at room temperature is employed. The conventional construction method can use epoxy resin, vinyl ester resin, unsaturated polyester resin, phenol resin, etc. as thermosetting resin, but in terms of room temperature curing, it is practically limited to epoxy resin, and the number of days until curing is There is a disadvantage that it takes about 3 days to 1 week depending on the outside temperature, and the construction period is long. In addition, the amount of epoxy resin to be applied in such a coating and impregnating method is usually the same as the weight of the used fiber sheet and is used more than necessary, which is uneconomical.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to reduce the amount of resin used by using a unidirectional sheet prepreg using aramid fiber, and to further reduce the amount of heat-curable resin by heat generated by energization for a short time. It is an object of the present invention to provide a method of reinforcing a structure for improving the workability and shortening the construction period, and a reinforcing material used for the same.

[0004]

Under such circumstances, the present inventors have conducted intensive studies and have found that a unidirectional sheet whose warp is substantially made of aramid fiber has a conductive tape or a conductive wire as a warp or a conductive tape or a conductive wire. After attaching a prepreg of a unidirectional sheet in which a tape or a conductive wire is woven as a warp and a weft to a structure, the conductive tape or the conductive wire is energized, and the thermosetting resin impregnated with heat generated by the energization is shortly applied. It has been found that if the curing is carried out, the working period can be shortened and the amount of epoxy resin used can be reduced, and the present invention has been completed.

That is, according to the present invention, a reinforcing sheet in which a conductive tape or a conductive wire is woven as a warp in a unidirectional sheet whose warp is substantially made of aramid fiber, or a conductive tape or a conductive wire is further woven as a weft in the reinforcing sheet. It is intended to provide a reinforcing material comprising a prepreg obtained by impregnating a thermosetting resin into a reinforcing sheet.

Further, the present invention provides a reinforcing method for winding the reinforcing material around a structure, applying an electric current to the conductive tape or the conductive wire to generate heat, curing the resin, and reinforcing the structure. It is.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a reinforcing sheet to be prepreg will be described with reference to FIGS. FIG.
FIG. 2 is a schematic view of a reinforcing sheet according to the first embodiment, and FIG.
FIG. 2 is a schematic view showing a conductive tape or a conductive wire portion of FIG. 1. In the reinforcing sheet according to the first embodiment, the unidirectional sheet substantially made of aramid fiber refers to a woven fabric using aramid fiber as at least a main fiber of a warp,
The woven fabric is further woven with a conductive tape or a conductive wire as a warp. The outline of the appearance is, as shown in FIGS. 1 and 2, a unidirectional woven fabric sheet 10 using aramid fibers for the warp 1, and the warp 1 and the conductive tape or the conductive wire 3 are passed in the left-right direction. Formed. In FIG. 1, the gap between the warp yarns changes depending on the number of the warp yarns to be driven per unit width. The weft 2 is a continuous or discontinuous yarn that is passed through in the up-down direction while knitting the warp yarn 1 and is formed coarsely horizontally. Further, both ends 3a and 3b for connecting the conductive tape or the conductive wire 3 in parallel are connected to an energizing device not shown in the figure.

Aramid fibers used for warp are used to give strength. The aramid fiber is not particularly limited, but has a tensile strength of 15 g / d or more and a Young's modulus of 5 or more.
Aramid fibers of at least 00 g / d (d means denier) are preferred. The number of twists of the aramid fiber is preferably as small as possible, and the number of twists is 5 to 50.
Times / m. If the number of twists increases, the Young's modulus of the sheet decreases, and the effect of shear reinforcement or bending reinforcement, which is the purpose of seismic reinforcement, decreases, which is not preferable. The basis weight of the unidirectional sheet is usually 200 to 100, excluding the weight of the weft.
0 g / m ² . The number of warp yarns per unit width is easily determined from the thickness of the aramid fiber used and the basis weight of the unidirectional sheet.

In the present invention, the conductive tape used as the warp is not particularly limited as long as it is a tape-shaped heating element that generates heat when energized, and for example, a composite of ethylene tetrafluoride resin and conductive carbon And a tape-like material obtained by finely cutting the fluororesin sheet heating element. The width of the tape is preferably in the range of 1 to 10 mm, and the thickness of the tape is preferably in the range of 0.075 to 0.20 mm. If the width of the tape or the thickness of the tape is less than the above range, the resistance value per unit length of the tape becomes large, and the voltage at the time of energization becomes undesirably high. If the width of the tape or the thickness of the tape exceeds the above range, the rigidity of the tape increases and it is difficult to use the tape as a warp. Further, the conductive tape preferably has excellent heat resistance and cold resistance.

[0010] In the present invention, the conductor used as the warp is not particularly limited, but is preferably a metal having a good conductor and a large calorific value, and examples thereof include a nickel-chromium alloy and an iron-chromium alloy. The diameter of the conductor is preferably in the range of 0.05 to 1.0 mm. If the diameter of the conductor is too small, the resistance of the conductor will be too large,
The voltage during energization is increased, which is not preferable. If the diameter of the conducting wire is too large, it is difficult to use as a warp, and the rigidity of the reinforcing sheet is increased, the flexibility is impaired, and the sheet is hardly wound around the outer surface of the structure.

The weaving interval of each conductive tape or conductive wire used as a warp (also referred to as a driving interval, hereinafter referred to as a "weaving interval") is preferably in the range of 1 to 5 cm. When the weaving interval is within this range, the entire surface of the prepreg-formed unidirectional sheet is uniformly heated by energization, so that the impregnated thermosetting resin such as an epoxy resin can be uniformly cured. If the weaving interval is less than the above range, more conductive wires and the like are required than necessary, which is wasteful and tends to cause problems in manufacturing. Further, even if the temperature exceeds the above range, the thermosetting resin cannot be uniformly heated and cured.

In the present invention, the weft is not particularly limited, and organic fibers such as nylon, polyester, cotton, and aramid fibers are used.

FIG. 3 is a schematic view of a reinforcing sheet according to a second embodiment, and FIG. 4 is a schematic view showing a conductive tape or a conductive wire portion of FIG. The difference between the reinforcing sheet 20 according to the second embodiment and the reinforcing sheet 10 according to the first embodiment is that the reinforcing sheet 20 according to the first embodiment is different from the reinforcing sheet 10 according to the first embodiment.
Furthermore, a conductive tape or conductive wire is woven into the weft so that the warp conductive tape or conductive wire and the weft conductive tape or conductive wire are in contact with each other. That is,
3 and 4, in the unidirectional woven sheet 20,
The warp 1 and the conductive tape or the conductive wire 3 are formed to pass in the left-right direction. The weft 2 and the conductive tape or the conductive wire 4 are passed vertically while knitting the warp 1, and are formed coarsely laterally. The weft 2 is a continuous or discontinuous yarn. At this time, the conductive tape or conductor 3 of the warp and the conductive tape or conductor 4 of the weft are in contact with each other to form a contact portion 5. Also,
Wefts 41, 41 located at both ends of the unidirectional sheet 20
Are connected at both ends to form loops 71a, 71
b, and both connection ends 7a, 7b extending from the loops 71a, 71b are connected to a current-carrying device, not shown.

The weaving interval between the conductive tape or the conductive wire 4 is preferably in the range of 10 to 40 cm. This is usually when a unidirectional sheet is made, then cut to a fixed length and wound around an existing concrete column that needs reinforcement.
It is determined by overlapping and winding both ends about 20 to 40 cm. That is, if the weft conductive tape or the conductive wire 3 is present in the overlapped portion, the entire surface of the prepreg-formed sheet can be uniformly heated, and it is convenient for the connection with the power supply device.

In order to bring the conductive tape or conductor 3 of the warp and the conductive tape or conductor 4 of the weft into contact with each other, an uncoated conductive tape or conductor may be used.
In addition, as the energizing method, the loop circuits 71a, 71
The method is not limited to a method of connecting a power supply to both connection ends 7a and 7b extending from 1b. For example, without forming a loop,
The ends 72a of the wefts 41 at both ends of the one-way sheet,
72b may be directly connected to an energizing device not shown in the figure. As described above, according to the second embodiment, since the conductive tapes or wires 3 and 4 of the warp and the weft are in contact with each other, all the conductive tapes or wires generate heat, and the warp It is not necessary to connect conductive tapes and conductive wires used in the parallel connection, and the workability is remarkably improved.

In the present invention, a method for producing a prepreg from the reinforcing sheet is not particularly limited, and is performed according to a known method. That is, a mixture of a thermosetting resin and a curing agent may be applied to a reinforcing sheet made of a unidirectional sheet and dried. As the thermosetting resin,
Phenol resins, epoxy resins, polyurethane resins, unsaturated polyester resins, vinyl ester resins, polyimide resins, and the like can be mentioned. Of these, epoxy resins and phenol resins are preferred in terms of strength, ease of handling, cost, and the like. The amount of resin impregnated in the reinforcing sheet to obtain the prepreg of the present invention is 5 to 5 weight of the prepreg.
It is 30%, preferably 10 to 25%. If the amount of the impregnated resin is small, the fiber cannot be sufficiently restrained to be cured, and if it is too large, the amount of the resin used is unnecessarily increased, which is uneconomical.

As a procedure of a method of reinforcing a structure using a reinforcing material made of a prepreg of the present invention, first, a reinforcing material (preprep) is wrapped around a structure, and a current is applied to the conductive tape or conductive wire. Heat is generated to cure the resin and reinforce the structure. The structure is not particularly limited, and is a portion requiring strength such as a civil structure such as a bridge, a tank and a steel tower; a road structure; a river, a harbor or a marine structure; Existing concrete columns or the like that require reinforcement for earthquake countermeasures and the like are suitable. First,
In order to keep the prepreg of the present invention in close contact with the surface of the concrete column, a primer is applied to the concrete surface. Next, the prepreg sheet cut into a fixed length is wound. Next, an electric current is applied to the conductive wires protruding from both ends of the prepreg to generate heat and harden the resin. When winding two or more layers, it is preferable to apply a primer each time. That is, the primer is applied on the cured sheet, and the same operation is repeated to wind the required number of sheets. However, if the prepreg has tackiness (adhesiveness) and adheres to the concrete surface, the primer is unnecessary. Further, if necessary, a thermosetting resin can be applied to the prepreg before the resin is cured by the heat generated by the conductive wire. The heating holding temperature and the curing time by energization vary depending on the type of thermosetting resin used, the curing start temperature, and the like, and are appropriately determined according to the conditions at the time of use.

[0018]

Next, the present invention will be described in more detail with reference to examples, but this is merely an example and does not limit the present invention. Example 1 (Preparation of reinforcing sheet) Aramid fiber "Twaron H" was used for the warp.
M "(manufactured by Akzo Nobel Co., Ltd.) using 3000 denier fiber, using 500 denier polyester fiber for the weft, and applying a weight of 415 g / m ² (excluding the weight of the weft) to the unidirectional sheet. A 1 mm nickel-chromium alloy wire was woven at 2 cm intervals using a warp to produce a reinforcing sheet. (Preparation of Prepreg) A mixture of bisphenol-type epoxy resin as a thermosetting resin and methyltetrahydrophthalic anhydride as a curing agent was applied to the reinforcing sheet and dried to obtain a prepreg having a resin component of about 25%.

(Reinforcing method) In order to keep the prepreg in close contact with the surface of the concrete column, an epoxy resin-based primer was applied to the concrete surface, and then a sheet of the prepreg cut into a fixed length was further wound. As shown in FIG. 2, the conductors extending from both ends of the prepreg were connected, an electric current was applied, heat was generated, and the resin was held at 120 ° C. for 1 hour to cure the resin. The amount of resin used is about 200 g / m
² (resin amount in prepreg: about 150 g / m ² , primer: about 50 g / m ² ). Further, the tensile strength of the seismic retrofitting material after curing of the resin is 61 t / m, and the elastic modulus is 1
It was 1.0 ton weight / mm ² .

Example 2 (Preparation of reinforcing sheet) A reinforcing sheet similar to that of Example 1 was prepared. (Preparation of prepreg) A mixture of a resol type phenol resin as a thermosetting resin and methyltetrahydrophthalic anhydride as a curing agent was applied to the reinforcing sheet and dried to obtain a prepreg having a resin component of about 20%. (Reinforcement method) The same method as in Example 1 was used, except that the curing condition of the resin was set at 140 ° C. for 1 hour. The amount of resin used was about 160 g / m ² (about 110 g of resin in prepreg).
g / m ² , and the primer was about 50 g / m ² ). Further, the tensile strength of the seismic retrofitting material after curing of the resin was 60 t / m, and the elastic modulus was 10.9 t / mm ² .

Example 3 (Preparation of reinforcing sheet) Example 1 was repeated except that a 0.2 mm-diameter iron-chromium alloy wire was used as a warp instead of a 0.1 mm-diameter nickel-chromium alloy wire. Performed in a similar manner. (Preparation of Prepreg) A mixture of bisphenol-type epoxy resin as a thermosetting resin and methyltetrahydrophthalic anhydride as a curing agent was applied to the reinforcing sheet and dried to obtain a prepreg having a resin component of about 22%. (Reinforcement method) The same method as in Example 1 was used. The amount of resin used was about 180 g / m ² (the amount of resin in prepreg was about 1
20 g / m ^2, was a primer of about 60g / m ^2).
The tensile strength of the seismic retrofitting material after curing of the resin was 62 tons / m, and the elastic modulus was 11.2 tons / mm ² .

Example 4 (Preparation of reinforcing sheet) Aramid fiber "Twaron H" was used for the warp.
M "(manufactured by Akzo Nobel Co., Ltd.) using 3000 denier fiber, using 500 denier polyester fiber for the weft, and applying a weight of 415 g / m ² (excluding the weight of the weft) to the unidirectional sheet. .2 mm nickel-chromium alloy wire is woven at 2 cm intervals as warp yarns, and the wire diameter is 0.2 mm.
A reinforcing sheet was prepared by weaving a 2 mm nickel-chromium alloy wire as a weft at 20 cm intervals. (Preparation of prepreg) A mixture of bisphenol-type epoxy resin as a thermosetting resin and methyltetrahydrophthalic anhydride as a curing agent was applied to the reinforcing sheet and dried to obtain a prepreg having a resin component of about 21%. (Reinforcement method) The same procedure as in Example 1 was carried out, except that the prepreg was used and the conductors protruding from both ends of the prepreg were connected as shown in FIG. The amount of resin used is about 180 g /
m ² (the amount of resin in the prepreg was about 120 g / m ² , and the primer was about 60 g / m ² ). Further, the tensile strength of the seismic retrofitting material after curing of the resin is 60 tons / m, and the elastic modulus is 1
It was 0.8 ton weight / mm ² .

Example 5 (Preparation of reinforcing sheet) Aramid fiber "Twaron H" was used for the warp.
M "(manufactured by Akzo Nobel Co., Ltd.) using 3000 denier fiber, using 500 denier polyester fiber for the weft, and applying a weight of 415 g / m ² (excluding the weight of the weft) to the unidirectional sheet. 5 mm width and 0.1 mm thickness of "Fluorotron" (manufactured by Daikin Industries, Ltd.), a tape-shaped material made of a 2 mm iron-chromium alloy wire as a warp at 3 cm intervals and made of a fluororesin sheet heating element. Was woven at an interval of 20 cm using as a weft to prepare a reinforcing sheet. (Preparation of Prepreg) A mixture of bisphenol-type epoxy resin as a thermosetting resin and methyltetrahydrophthalic anhydride as a curing agent was applied to the reinforcing sheet and dried to obtain a prepreg having a resin component of about 25%. (Reinforcement method) The same procedure as in Example 1 was carried out except that the prepreg was used and conductive tapes protruding from both ends of the prepreg were connected as shown in FIG. The amount of resin used is about 2
00 g / m ² (resin amount of about 140 g / prepreg
m ² , about 60 g / m ^{2 of} primer). The tensile strength of the seismic retrofitting material after curing of the resin is 61 tons /
m, and the elastic modulus was 11.0 ton weight / mm ² .

Comparative Example 1 3000 denier fiber of aramid fiber "Twaron HM" (manufactured by Akzo Nobel) was used for the warp and 500 for the weft.
Using denier polyester fiber, weight per unit 415g
/ M ² unidirectional sheet woven fabric was made on a shuttle loom. An epoxy resin primer is applied to the concrete surface in order to hold the prepared seismic reinforced sheet consisting of a unidirectional sheet in close contact with the surface of the concrete column,
Next, the unidirectional sheet cut to a fixed length was further wound. Next, a room temperature-curable epoxy resin was applied from above, and allowed to stand. It took about 3 days for complete curing. The amount of resin used was about 550 g / m ² . The tensile strength of the reinforcing sheet (FRP) after resin curing is 60 tons /
m, and the elastic modulus was 10.8 ton weight / mm ² .

As is evident from the results of Examples 1 to 5 and Comparative Example 1, all of the examples were compared with the conventional seismic reinforcement method using carbon fiber or aramid fiber not according to the present invention. The amount could be reduced to about 1/3 and the time to cure could be significantly reduced.

[0026]

The reinforcing material of the present invention uses a small amount of thermosetting resin, and can cure the thermosetting resin in a short time by the heat generated by energization. Therefore, when the reinforcing material of the present invention is used, the construction period required for construction can be shortened. Also,
The reinforcing material of the present invention is equivalent to those of the conventional method in physical properties such as tensile strength and elastic modulus.

[Brief description of the drawings]

FIG. 1 is a schematic view of a reinforcing sheet according to a first embodiment.

FIG. 2 is a schematic view of a conductive tape or a conductive wire portion of FIG. 1;

FIG. 3 is a schematic view of a reinforcing sheet according to a second embodiment.

FIG. 4 is a schematic view of a conductive tape or a conductive wire portion of FIG. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Warp (aramid fiber) 2 Weft 3 Conductive tape or conductor as a warp 4 Conductive tape or conductor as a weft 3a, 3b, 7a, 7b Conductor part connected to a current supply device 5 Contact part 10, 20 Reinforcement sheet (Unidirectional sheet)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08J 5/24 CFC C08J 5/24 CFC 4F211 E04G 23/02 E04G 23 / 02F // B29K 101: 10 105 : 08 (72) Inventor Masayuki Shimizu 2-5-8 Higashishinagawa, Shinagawa-ku, Tokyo Sumitomo Bakelite Co., Ltd. (72) Inventor Takao Ota 2-5-2-8 Higashishinagawa, Shinagawa-ku, Tokyo Sumitomo Bakelite Co., Ltd. (72) Inventor Fumio Yamamoto 6-10-73 Minamitsukaguchi-machi, Amagasaki-shi, Hyogo F-term in Shinto Paint Co., Ltd. AE26 AF02 AG03 AH21 AJ01 AJ16 AJ22 AK05 AL17 4F100 AA37A AA37H AB01A AB02A AB13A AB16A AB31A AK01A AK18A AK33A AK47A AK53A AT00B BA01 BA 02 CA23A DG13A DG18A DG19A DH01A EJ82A GB90 JB13A JG01A JK02 JK07 JL02 4F203 AA37 AA39 AD03 AD15 AD16 AG01 AH43 AH46 DA12 DB01 DC12 DK07 4F211 AA37 AA39 AD03 AD15 AD16 AG01 SD03 SG01 SD01 SG16 SD01 SD01

Claims (5)

[Claims] 1. A reinforcing sheet in which a conductive tape or a conductive wire is woven as a warp in a unidirectional sheet in which a warp is substantially made of aramid fiber, or a reinforcing sheet in which a conductive tape or a conductive wire is further woven as a weft into the reinforcing sheet. A reinforcing material comprising a prepreg impregnated with a curable resin. 2. The reinforcing material according to claim 1, wherein the conductive tape is a tape-shaped material of a sheet heating element made of fluororesin, which is a composite of tetrafluoroethylene resin and conductive carbon. 3. The conductor according to claim 1, wherein the conductor is a nickel-chromium alloy or an iron-chromium alloy.
Reinforcement as described. 4. The reinforcing material according to claim 1, wherein the thermosetting resin is an epoxy resin or a phenol resin. 5. Reinforcing the reinforcing material according to any one of claims 1 to 4 around a structure, applying an electric current to the conductive tape or the conductive wire to generate heat and curing the resin to reinforce the structure. Reinforcement method characterized by doing.