JP2000033617A - Reinforcing material and reinforcement technique - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cure a heat curable resin in a short time by using a conductor as a core in the weft of a prepreg of a unidirectional sheet using an aramid fiber and also a covering yarn made up of a helically wound organic fiber as a core and attaching the prepreg to a structure and further energizing the conductor. SOLUTION: A unidirectional fabric sheet 10 is made up of an aramid fiber as a warp 1. A weft 2 obtained by spinning together with an organic fiber using a conductor as a core is a continuous yarn which is roughly formed mutually with the warp 1 crosswise after interweaving the warp 1 with the weft 2 vertically. In addition, the conductor to be connected to an energizing device is exposed on both end parts 3a, 3b of the continuous yarn. For a covering yarn consisting of the organic fiber wound around the conductor helicallky as a core, the fiber of nylon, polyester, cotton or aramid which is of a common commercial grade is used. A prepreg which is obtained by impregnating the unidirectional fabric sheet 10 made of the aramid fiber with a heat curable resin is wound around a structure and the conductor is hearted by applying current. Thus the structure is reinforced by curing the resin.

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 the fiber and wind it around a structure such as a concrete column requiring reinforcement. 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 prepreg of a unidirectional sheet using aramid fiber, and to further reduce the amount of heat-curable resin by heat generated by energization. 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 as a result, have found that a weft of a prepreg of a unidirectional sheet using aramid fiber (warp), a conductive wire as a core, and an organic fiber After covering the prepreg on a structure using a core yarn spun with organic fibers with a covering yarn or a conductive wire wound spirally,
By energizing the conductive wire and curing the thermosetting resin in a short time by the heat generated by the energization, it was found that the work period could be shortened and the amount of epoxy resin used could be reduced, leading to the completion of the present invention. Was.

That is, according to the present invention, a covering yarn in which a conducting wire is used as a core and organic fibers are spirally wound or a core yarn in which a conducting wire is used as a core and spun with an organic fiber is used as the weft of a unidirectional sheet, and the warp is used as an aramid fiber. And a reinforcing material comprising a prepreg obtained by impregnating a thermosetting resin into a unidirectional sheet made of

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

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the reinforcing material of the present invention, a unidirectional sheet made of aramid fiber refers to a woven fabric using aramid fiber for at least the warp. The outline of the appearance is
As shown in FIG. 1, a unidirectional woven fabric sheet 10 using aramid fibers for the warp 1 is formed by passing the warp 1 in the left-right direction. In FIG. 1, the gap varies depending on the number of warp yarns per unit width. In addition, the weft 2 which is made of a conductive wire as a core, wound with an organic fiber or made of a conductive wire as a core, and spun together with the organic fiber is a continuous yarn which is passed through in the up and down direction while knitting the warp yarn 1 and is coarsely formed side by side,
At both ends 3a and 3b, conductors connected to a current supply device not shown in the figure are shown. Aramid fibers used for warp are used to give strength. The aramid fiber is not particularly limited, but is preferably an aramid fiber having a tensile strength of 15 g / d or more and a Young's modulus of 500 g / d or more (d means denier, the same applies hereinafter). Also, the number of twists of the aramid fiber is preferably as small as possible,
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 1000 g / m ² , excluding the weight of the weft. 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.

[0008] The conductor used for the weft is a good conductor metal,
Those having a large calorific value are preferable, and examples thereof include nickel-chromium alloy and iron-chromium alloy conductors. The diameter of the conductor is preferably in the range of 0.05 mm to 1.0 mm. If the diameter of the conductive wire is large, the diameter after winding the organic fiber described below becomes too large, which is not preferable.

As the weft, a covering yarn in which organic fibers are spirally wound around the above-mentioned conducting wire or a core yarn spun with organic fibers around the above-mentioned conducting wire is used. The conventional seismic retrofitting method using carbon fiber or aramid fiber sheets is a method of cutting these fiber sheets into fixed lengths, winding them around concrete columns that need reinforcement, bonding both ends together, and fixing them with epoxy resin. However, in the method of reinforcing a structure using a prepreg according to the present invention, a conductive wire is coated with an organic fiber having an insulating property in order to prevent a short circuit at a portion where the conductive wire overlaps when energized.

[0010] In a covering yarn in which a conductive wire is used as a core and organic fibers are spirally wound, the organic fibers are not particularly limited, and ordinary nylon, polyester, cotton, and aramid fibers can be used. The spiral winding density is not particularly limited, but may be 300 to 900 turns / m.
Degree, preferably 500 to 700 times / m. In addition, after the left spiral winding, the right spiral winding is further performed thereon, or vice versa, after the right spiral winding, the left spiral winding is further performed thereon. A so-called double covering yarn is preferred.

As the organic fibers used for producing the core yarn of the conductive wire, the same fibers as those used in the covering yarn can be used. The core yarn is formed by supplying a conductive wire to a front roller of a spinning machine, and spinning the core yarn with the core wire wrapped with organic fibers. Further, in order to prevent the fibers on the surface of the core yarn from fraying, the organic fibers may be further spirally wound around the outer layer of the core yarn.

In the unidirectional sheet made of the aramid fiber of the present invention, it is necessary to continuously form the wefts for energization. Therefore, as a loom for producing the unidirectional sheet, the wefts must be continuous. A shuttle loom that can be used is preferred.

The thermosetting resin to be impregnated to produce a prepreg from the unidirectional sheet made of the aramid fiber includes phenol resin, epoxy resin, polyurethane resin, unsaturated polyester resin, vinyl ester resin, polyimide resin and the like. However, epoxy resin and phenol resin are preferred from the viewpoints of strength, ease of handling, cost and the like. The amount of resin impregnated in the unidirectional sheet to obtain the prepreg of the present invention is 5 to the weight of the prepreg.
-30%, preferably 10-25%. 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 uneconomic.

As a procedure of a method of reinforcing a structure using the prepreg of the present invention, first, a reinforcing material (preprep) is wound around the structure, and an electric current is applied to the conductor to generate heat.
The resin is cured to reinforce the structure. As a structure,
Not limited, civil engineering structures such as bridges, tanks and steel towers; road structures; rivers, harbors or marine structures; sites where strength is required, such as architectural structures. An existing concrete column or the like which is required is preferable. First, a primer is applied to the concrete surface in order to keep the prepreg of the present invention in close contact with the surface of the concrete column. 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, a 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. Also, if necessary, before the resin is hardened by heating the conducting wire,
A thermosetting resin can be applied to the prepreg. The heating and holding temperature and the curing time by energization vary depending on the type of the thermosetting resin used, the curing start temperature, and the like, and are appropriately determined according to the conditions at the time of use.

[0015]

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 A 75 denier polyester fiber is wound around a nickel-chromium alloy wire having a wire diameter of 0.1 mm at a rate of 600 turns / m in a left spiral shape, and then further wound on the nickel chromium alloy wire in a right spiral shape.
By winding at a rate of 00 turns / m, a so-called double covering yarn was produced. The aramid fiber "Twaron HM" (manufactured by Akzo Nobel) having a denier of 3000 is used for the warp, and the double covering yarn is used for the weft. The basis weight is 415 g / m ² (excluding the weight of the weft).
The unidirectional sheet woven fabric was produced on a shuttle loom. A mixture of a bisphenol-type epoxy resin as a thermosetting resin and methyltetrahydrophthalic anhydride as a curing agent was applied to the produced unidirectional sheet, and dried to obtain a prepreg having a resin component of about 25%.

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. An electric current is applied to the conducting wire extending from both ends of the prepreg to generate heat, and
The resin was cured by holding at 1 ° C. for 1 hour. The amount of resin used was about 200 g / m ² (about 150 g of resin in prepreg
/ M ² , about 50 g / m ^{2 of} primer). Also,
The tensile strength of the seismic retrofitting material after resin curing is 61 tons /
m, and the elastic modulus was 10.8 ton weight / mm ² .

Example 2 In Example 1, a resole type phenol resin was used in place of the bisphenol type epoxy resin, and a resin component of about 2
A 0% prepreg was obtained, and this prepreg was used and wound around concrete in the same manner as in Example 1, and kept at 140 ° C. for 1 hour to cure the resin. The amount of resin used is about 160
g / m ² (resin weight of about 110g / m ² in the prepreg, a primer of about 50 g / m ²⁾ was. The tensile strength of the earthquake-resistant reinforcing sheet after curing of the resin was 60 tons / m, and the elastic modulus was 10.3 tons / mm ² .

Example 3 A core yarn spun using a 50 mm long staple fiber of aramid fiber “Twaron” (manufactured by Akzo Nobel Co., Ltd.) was prepared using a lead wire of an iron-chromium alloy having a wire diameter of 0.1 mm as a core. Further, a polyester fiber of 150 denier was spirally wound around the surface of the core yarn at a rate of 200 turns / m. Using 3000 denier fiber of aramid fiber "Twaron HM" (manufactured by Akzo Nobel) for the warp yarn,
The above-mentioned core yarn is used for the weft, and the basis weight is 415 g / m.
² A unidirectional sheet of woven fabric (excluding the weight of the weft) was produced on a shuttle loom. The procedure was performed in the same manner as in Example 1 except that the above-described unidirectional sheet was used. The resin component in the prepreg is about 24%, and the amount of resin used is about 190 g / m
² (resin weight of about 140 g / m ² in the prepreg, a primer of about 50 g / m ²⁾ was. The tensile strength of the earthquake-resistant reinforcing sheet after resin curing is 62 tons / m, and the elastic modulus is 11.
It was 2 tons 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 make the prepared seismic reinforcement made of the unidirectional sheet adhere to the surface of the concrete column, and then the unidirectional sheet cut to a fixed length is removed. Wound more. 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 earthquake-resistant reinforcing sheet after curing of the resin was 60 ton-force / m, and the elastic modulus was 10.5 ton-force / mm ² .

As is evident from the results of Examples 1 to 3 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.

[0021]

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 unidirectional sheet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Warp (aramid fiber) 2 Weft 3a, 3b Conductor 10 Unidirectional sheet

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) D03D 15/00 D03D 15/02 A 4L036 15/02 C 4L048 E04C 5/07 E04C 5/07 E04G 23/02 F E04G 23 / 02 C08J 5/24 CEZ // C08J 5/24 CEZ C08L 61/06 C08L 61/06 63/00 Z 63/00 77/10 77/10 B29C 67/14 X B29K 105: 06 (72) Inventor Tanaka 6-73 Minamitsukaguchi-cho, Amagasaki-shi, Hyogo Prefecture Inside Shinto Paint Co., Ltd. (72) Inventor Fumio Yamamoto 6-10-73 Minamitsukaguchi-cho, Amagasaki-shi, Hyogo Shinto Paint Co., Ltd. (72) Invention Person 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. F-term (reference) 2E164 AA01 AA05 AA11 BA06 CA17 EA05 2E176 AA04 BB29 4F072 AA04 AB02 AB06 AB11 AB17 AB18 AB22 AD13 AD16 A D23 AD28 AE01 AE03 AG03 AH21 AK05 AK20 AL17 4F205 AA36 AA37 AA39 AD03 AD15 AD16 AG01 AH47 AK09 HA02 HA23 HA33 HA37 HA45 HB01 HB11 HC02 HC14 HF05 HF23 HK04 HK05 HK17 HT03 HT3 CL02 HT13 H2 CL03 HT13 H2 CC03 HT13 H2 CM041 DC006 FA042 FA043 FA046 GL00 4L036 MA04 MA06 MA15 MA33 MA39 PA26 RA25 UA07 4L048 AA04 AA25 AA28 AA52 AB07 AB18 AC09 AC13 BA03 BA04 CA01 CA05 DA30 DA41 EB05

Claims (4)

[Claims] 1. A covering yarn in which a conductive wire is used as a core and organic fibers are spirally wound, or a core yarn which is used as a core and a conductive wire is used as a weft of a unidirectional sheet, and a warp yarn is made of an aramid fiber. A reinforcing material comprising a prepreg obtained by impregnating a thermosetting resin into a conductive sheet. 2. The reinforcing material according to claim 1, wherein the conductor is a nickel-chromium alloy or iron-chromium alloy conductor. 3. The reinforcing material according to claim 1, wherein the thermosetting resin is an epoxy resin or a phenol resin. 4. A reinforcing method of wrapping the reinforcing material according to claim 1 around a structure, applying an electric current to the conductive wire to generate heat, curing the resin, and reinforcing the structure.