JPH10121345A - Carbon fiber sheet and repair and reinforcement of concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject sheet which has an excellent workability and resin impregnation and is useful for repair and reinforcement of concrete structures by arranging a plurality of carbon fiber yarns having a loop strength over a specific value in parallel. SOLUTION: A plurality of carbon fiber yarns having a loop strength of >=1,000N per 0.9mm<2> cross section according to JIS L 1013 are arranged in parallel to form carbon fiber sheets of unidirectional or bidirectional woven fabric. These sheets has reduced fluffs on their surface and reduced filament breakage on the sheet surface, gives no unpleasant irritating feeling on the construction operation and occurs less fluffs on the impregnation rolling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for repairing and reinforcing carbon fiber sheets and concrete structures, and more particularly to a carbon fiber sheet suitable for repairing and reinforcing concrete structures and a method for repairing and reinforcing concrete structures using the same. Related to reinforcement method.

[0002]

2. Description of the Related Art Concrete structures such as bridges, tunnels, chimneys and buildings deteriorate due to neutralization of concrete and rust due to long-term use, increase in load due to reduction in the weight of passing vehicles, damage due to earthquakes and the like. Repairs and reinforcements have become necessary due to review of seismic standards for larger earthquakes.

[0003] As a typical method of repairing and reinforcing concrete structures, a steel plate reinforcing method of bonding a steel plate to concrete is known, but the steel plate is heavy and is difficult to handle. For these reasons, a carbon fiber sheet construction method that is more excellent in characteristics than iron has recently attracted attention. This method uses a so-called carbon fiber reinforced plastic (CF) in which a carbon fiber sheet is cured while impregnating the resin in the field.
This is a method of repairing or reinforcing with RP).

In repairing and reinforcing a concrete structure with a carbon fiber sheet, first, dirt such as oil adhering to the concrete surface is washed, cracks are filled with a putty or the like, and irregularities on the surface are mortar or putty. Correct it to make it smoother. Next, in order to improve the adhesion between the concrete and the CFRP, a primer is applied and left for about 24 hours to dry. After that, an epoxy resin that is liquid at room temperature and is cured at room temperature is applied as a matrix of CFRP, a carbon fiber sheet such as a carbon fiber fabric is laminated, and the distribution of the resin is made uniform with an impregnating roller or a rubber spatula. Then, the resin is impregnated into the carbon fiber sheet.
Further, a resin is applied thereon, and impregnation operation is performed with an impregnation roller or a rubber spatula, and this is repeated as necessary.

[0005] As described above, the carbon fiber sheet method has a feature that a concrete structure can be easily repaired or reinforced. However, carbon fibers have a large tensile modulus and are brittle, and are extremely fuzzy even among existing fibers. It has a defect that it is easy. Therefore, the fluff generated during the manufacturing process of the carbon fiber sheet adheres to the surface of the sheet, and when the fabric is handled at the construction site, the fluff is scattered. The sheet may be fluffed and adhere to the worker's skin. Since carbon fiber monofilaments are as thin as 5 to 15 microns in diameter, and have a large tensile modulus and are rigid, when they adhere to human skin, they feel itchy, and when rubbed, they pierce the skin,
Gives discomfort as tingling. In particular, at the construction site, there is a problem that the resin adheres to the worker's skin, and in summer, there are many places where the skin is exposed and sweat is attached, so that fluff is likely to adhere and discomfort increases.

[0006] Further, since the reinforcing portion of the concrete structure is generally located on the lower surface of the concrete surface or the outer surface of the columnar material, the uncured resin-impregnated carbon fiber fabric falls from the concrete surface before the resin is cured. A predetermined portion will not be reinforced by slipping or slipping. Further, when reinforcing the lower surface of the concrete surface, the resin drips and adheres to the worker, which is unsanitary, and fluff is likely to adhere. For this reason, the viscosity of the resin is set to a high value, but if the viscosity of the resin is high, the impregnation of the resin into the carbon fiber fabric becomes insufficient, or the concrete surface and the impregnated carbon fiber fabric, or the impregnated carbon fiber fabric In some cases, air was trapped between the carbon fiber fabric and the impregnated carbon fiber fabric and remained as voids. The resin cures and the concrete surface and CFRP
If there is a void in the space or in the CFRP, water will accumulate in the void due to long-term use, and freezing and thawing will be repeated, and from the void, between the concrete surface and CFRP, or C
There is a concern that cracks may occur in the FRP, leading to a reduction in the reinforcing effect.

[0007] Further, if the roller is strongly rolled in order to forcibly impregnate the resin with high viscosity, the arrangement of the carbon fibers is disturbed, the strength is reduced, or the space between the carbon fiber yarns is closed and air is released. There is a problem in that the sheet is not caught and is embraced or fluff is generated in the carbon fibers constituting the sheet.

[0008]

SUMMARY OF THE INVENTION The present invention focuses on such a current situation, and provides a carbon fiber sheet which does not give a worker an unpleasant sensation at the time of construction, is excellent in workability and resin impregnating property, and hardly causes voids to remain. Is to provide. Another object of the present invention is to provide a method for repairing and reinforcing a concrete structure using the carbon fiber sheet.

[0009]

Means for Solving the Problems In order to achieve the above object, in a sheet in which a large number of carbon fiber yarns are arranged in parallel, the carbon fiber yarns are JIS L 1013.
The hook strength measured according to the law is 0.9 mm in cross-sectional area.
There is provided a carbon fiber sheet characterized by being 1,000 N or more per ² pieces.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION
There was a request from workers to treat the carbon fiber sheet, which was unpleasant and unpleasant, and a request for improvement was made.When the cause was investigated, the number of fluffs and single fibers adhering to the surface of the carbon fiber sheet It was found that there was a relationship between the number of cut filaments and the tingling sensation. The number of fluff and the number of single fibers cut on the sheet are determined by the manufacturing conditions in the manufacturing process, such as the tension of the carbon fiber yarn,
It depends on the curvature of the guide in the yarn path, the surface damage of the guide, and the state of adhesion of impurities. However, even under the same conditions, there was a difference in the number of fluffs adhered to the sheet. In other words, even in the case of carbon fibers, depending on the production conditions, it is found that there are carbon fibers that are likely to generate fluff and carbon fibers that are less likely to generate fluff. It has been found that there is a relationship between the hooking strength between carbon fiber yarns used for the sheet and the tendency to generate fluff.

In the present invention, JIS L 1013
The hook strength measured according to the law is 0.9 mm in cross-sectional area.
It is necessary to be 1,000 N or more per ² .

When the hooking strength is less than 1,000 N, the resin impregnated as in the prior art has a tingling sensation. Many single fibers were observed. In addition, fluff adhered to the skin, and some of the flesh pierced the skin.

When the carbon fiber has a hooking strength of 1,000 N or more, the number of fluffs observed on the surface of the bobbin wound with the carbon fiber used for sheet production is small, and the carbon fiber adheres to the sheet surface. The number of fluffs and the number of cut single fibers on the sheet surface were also small. This sheet was actually used to reinforce the concrete structure at the construction site, and the resin was impregnated and defoamed with a grooved impregnation roll, but there was no tingling sensation.
The surface of the palm was observed with a magnifying glass, but no fluff was observed. That is, it indicates that the fluff scattered from the sheet was small, and the generation of fluff by the impregnating roll was significantly reduced.

The hooking strength of the carbon fiber yarn in the present invention is measured according to 7.7 of JIS L 1013 method. That is, as shown in FIG. 1, a loop is formed at the center between the grips of the carbon fiber yarns 1 and 2, and the tensile speed is 50 mm / min.
Was determined, and the number of measurements was shown as an average value of 10 times. When the breaking load of the carbon fiber yarn is large and the yarn cannot be measured due to slipping at the gripping portion 3 before the yarn is cut, the both ends of the yarn are about 20 mm, and the room temperature thermosetting thermosetting is used. The FRP was solidified with a conductive resin, and this portion was gripped so that both ends of the carbon fiber yarns 1 and 2 were in contact with each other. The upper and lower gripping distances A and B were each set to be equal to 125 mm, and the FRP did not enter between the grippings. Further, the hooking strength is also controlled by the thickness of the carbon fiber yarn, but the present invention does not directly use the hooking strength of the yarn, but a method for evaluating the ease of fluffing of carbon fiber. Therefore, the thickness of the yarn is made substantially the same, and specifically, the cross-sectional area of the yarn is measured as substantially 0.9 mm ² . A cross-sectional area of substantially 0.9 mm ² is:
It means a cross-sectional area within a range of about 0.9 ± 0.1 mm ² . When the cross-sectional area is too small, the yarns are aligned so as to have a predetermined cross-sectional area.
With a predetermined cross-sectional area of five yarns, the yarn is divided into halves so as to minimize fuzz, and aligned with two yarns (2+
0.5) Make a book. Note that 0.1 × 10 ⁻³ N /
The yarns are aligned under the initial denier load. Also, when several yarns are aligned and the end is hardened with a thermosetting resin, the operation is performed under the same conditions as described above with an initial load applied. When the cross-sectional area of the carbon fiber of the yarn is too large, the yarn is divided so as to minimize fuzz, so that the cross-sectional area of the carbon fiber yarn is as described above.

Here, the cross-sectional area of the carbon fiber yarn means a value obtained by multiplying the cross-sectional area of the carbon fiber single fiber by the number of filaments. For convenience, the fineness (denier) of the yarn and the yarn Is a value calculated from the density (g / cm ³ ).

The carbon fiber used in the present invention is a multifilament, and the thickness of the carbon fiber yarn is 3,000 to 10
It is about 000 filament. The carbon fiber may be a polyacrylonitrile-based (hereinafter referred to as PAN-based) or pitch-based carbon fiber. However, in order to obtain a large reinforcing effect with a small amount of fiber, a carbon fiber having a high strength and a high elastic modulus, specifically, a tensile strength Is 3 GPa or more, preferably 4 GPa or more, more preferably 4.5 GPa or more, and the tensile modulus is 200 to 700.
Carbon fibers that are GPa are preferred. If the tensile strength of the carbon fiber yarn is within the above range, even if the amount of carbon fiber per sheet is small, a desired reinforcing effect can be obtained, so that the air permeability increases, that is, the impregnation property of the resin is further improved. I do.

A specific embodiment of the present invention will be described with reference to the drawings. FIG. 2 shows a unidirectional carbon fiber woven fabric as a carbon fiber sheet according to one embodiment of the present invention. In the figure, reference numeral 4 denotes a carbon fiber yarn, and a plurality of carbon fiber yarns are formed. Auxiliary yarns 5 arranged in parallel in the direction
Are so-called unidirectional woven fabrics interlaced with carbon fiber yarns.

FIG. 3 shows another embodiment of the carbon fiber sheet of the present invention. In the warp direction, the carbon fiber yarns 4 having substantially no bending are arranged in one direction in parallel with each other and in a sheet shape. The yarn group d of the weft auxiliary yarn 5 is located on both sides of the sheet surface of the aligned yarn group B, and the weft auxiliary yarn group
This is a unidirectional carbon fiber woven fabric in which the yarn group C of the warp direction auxiliary yarn 6 parallel to the carbon fiber yarn group forms a woven structure and integrally holds the yarn group. Such a woven fabric has no bending in the warp direction of the carbon fiber thread, so that stress is not concentrated even when molded and formed into carbon fiber reinforced plastic (CFRP), and high strength is obtained.

FIG. 4 shows another embodiment of the carbon fiber sheet of the present invention. In the figure, a large number of carbon fiber yarns 4 are arranged in parallel in the vertical direction, and the carbon fibers are also arranged in the horizontal direction. A so-called bidirectional carbon fiber woven fabric in which the yarns 7 are arranged in parallel so as to be orthogonal to the carbon fiber yarns 4 in the warp direction, wherein the carbon fiber yarns 4 in the warp direction and the carbon fiber yarns in the weft direction. 7 are alternately interlaced and have a flat organization.

FIG. 5 shows another embodiment of the carbon fiber sheet of the present invention. In the figure, a number of carbon fiber yarns 4 are arranged in parallel in the warp direction. And a mesh-shaped support 8 located on one side thereof and a binder 9. As the binder, it is preferable to use the same type as the matrix resin used in the molding of CFRP because the affinity with the matrix resin is good, and the amount of the binder is about 3 to 7% based on the weight of the carbon fiber. Good to be.

The carbon fiber sheet of the present invention usually takes the form of the woven fabric described above, but is a carbon fiber sheet in which a large number of carbon fiber yarns are arranged in parallel and the yarns are adhered to a support with a binder. May be.

In order to improve the resin impregnating property of the carbon fiber woven fabric as the carbon fiber sheet, the form of the woven fabric and the resin impregnating property were examined. Also, the state of bundle of carbon fibers in the carbon fiber yarn, the state of entanglement of carbon fibers, and the same carbon fiber woven fabric vary depending on the warp and weft restraint conditions. It was found that the impregnation state greatly depends on the state. Also,
In the course of this study, it was discovered that the permeability of the fabric and the impregnation of the resin were closely related.

Through these experiments, good resin impregnation can be obtained only when the air permeability of the carbon fiber sheet is in accordance with JIS.
20 to 300 cc / cm ² / sec as measured by L 1096 method
Met. When the ventilation rate is less than 20 cc / cm ² / sec, the bulk density of the carbon fibers constituting the carbon fiber yarn becomes small, that is, the space formed between the carbon fibers is small, or the carbon fiber yarn of the carbon fiber sheet is formed. The gap formed in the gap 4 was small, the resin impregnating property was poor, and air was trapped inside the CFRP or between the concrete and the CFRP, and large voids entered. Further, the sheet having a ventilation rate exceeding 300 cc / cm ² / sec has a large gap 4 between carbon fiber yarns, has too much drapability, and it is difficult to apply the woven fabric straight to concrete, and the workability is poor. .

The air permeability of the carbon fiber sheet is 20 to 300 cc
/ cm ² / sec, CFRP and concrete and C
There are no large voids between the FRPs, the carbon fiber has good resin impregnation and good workability.

The air permeability of the sheet in the present invention is measured by the following method.

The measurement of the air permeability was in accordance with the air permeability A method of Section 6.27 of JIS L 1096 method. That is, the area of one end of the cylinder is 20 cm × 20 c in a ventilation hole having a size of 38.3 cm ^2.
m sheet test piece was attached by a predetermined method, and the suction fan was adjusted with a rheostat so that the inclination type barometer indicated a pressure of 1.27 cm of water column, and the pressure indicated by the vertical type barometer at that time was used. The amount of air passing through the sheet test piece (cc / c
m ² / sec) was determined and the average value of the results of the five measurements was taken as the ventilation rate. The sample was left in a room at a temperature of 20 ° C. and a humidity of 65% for 24 hours, and then measured in that atmosphere. In addition,
In the examples described later, a Frazier-type tester AP-360 manufactured by Daiei Kagaku Seiki Seisaku-Sho, Ltd. was used as a ventilation meter.

It is preferable that a sizing agent is attached to the carbon fiber thread used in the present invention in an amount of 0.2 to 1.5% by weight based on the weight thereof. When the sizing adhesion amount of the carbon fiber yarn is too small, the bulk density of the carbon fiber becomes large, that is, it is preferable in that the space formed between the carbon fibers is large and the resin is easily impregnated, but the carbon fiber is brittle. Fuzz is generated at the time of manufacturing a sheet such as a woven fabric, and a large amount of fuzz is attached to the sheet. When such a sheet is used for molding by the hand impregnation method, when handling the sheet at a construction site, the fluff adheres to and sticks to the skin, which increases the discomfort of the worker. Also, if the sizing adhesion amount is too large, the above-mentioned problem of fluff is solved, but the carbon fibers adhere with the sizing agent and converge, the space formed by the carbon fibers decreases, and the impregnation of the resin decreases. May get worse.

In the present invention, the sheet preferably has a carbon fiber weight of 200 to 400 g / m ² . If the basis weight of the carbon fiber is less than 200 g / m ² , it is preferable from the viewpoint of the impregnation of the resin, but the number of laminations is increased to perform the necessary reinforcement. Therefore, not only the work of impregnating the resin is troublesome and workability is deteriorated, but also a sheet having a large drapability becomes difficult, and it is difficult to stick the sheet straight to concrete, and the workability is deteriorated. If the basis weight of the carbon fiber exceeds 400 g / m ² , the impregnating property of the resin deteriorates, and the weight of the resin-impregnated sheet increases, so that the uncured resin or the resin-impregnated carbon fiber sheet from the concrete surface becomes Predetermined portions will not be reinforced by dropping or slipping before curing.

The auxiliary yarn in the present invention is preferably a glass fiber because it does not shrink even when the woven fabric is stored at room temperature or by heat treatment. When the auxiliary yarn as the weft shrinks, the weaving density of the carbon fiber yarn of the warp yarn increases, the reinforcing effect of the setting differs, and as the width decreases, the reinforcing area becomes smaller than originally planned. Not preferred.

Further, as shown in FIG. 4, the carbon fiber woven fabric of the present invention adheres a low-melting polymer 10 extending linearly or dotwise in the longitudinal direction of the carbon fiber yarn in the warp direction,
It is preferable that the low-melting polymer is a so-called blind woven fabric in which the low-melting polymers are bonded at the intersections with the yarns orthogonal to each other, that is, the weft carbon fiber yarns. Although FIG. 4 shows an example in which the low melting point polymer is attached to the weft yarn, it may be attached to the warp yarn or may be attached to the warp yarn and the weft yarn in two directions.

As shown in FIGS. 2 and 3, in a unidirectional carbon fiber woven fabric, a weft-direction auxiliary yarn adheres a low-melting polymer 10 and a warp-oriented carbon fiber yarn is formed by the polymer. May be adhered to each other at their intersections.

In this way, the stagnant woven fabric does not fray even when the woven fabric is cut at the site, and the woven yarn is not damaged even if it is rolled strongly for resin impregnation. It does not meander and cause a decrease in the strength and rigidity of the CFRP.

The amount of the low-melting polymer adhered is preferably 6.0 g / m ² or less because a large amount impairs resin impregnation or lowers the mechanical properties of CFRP. However,
If it is less than 0.5 g / m ² , the eye-catching effect is diminished.
0.5-6.0 g / m < ² > is preferable.

In the case of a unidirectional carbon fiber woven fabric, when a large amount of these low-melting polymers adhere to a thin auxiliary yarn, the auxiliary yarn basically does not support reinforcement, but the starting point of destruction starts from the auxiliary yarn. In order to prevent such an effect and to exert an eye-opening effect, the amount of the low-melting polymer adhered to the auxiliary yarn is preferably 50% by weight or less of the auxiliary yarn.

The low melting point polymer used in the present invention is usually
It is selected from nylon, copolymer nylon, polyester, vinylidene chloride, vinyl chloride, and polyurethane. Among them, copolymer nylon is particularly preferably used because it can melt the polymer at a low temperature, has a strong adhesive force, and can obtain an expected effect with a small amount of use.

Next, a method of repairing and reinforcing the concrete structure according to the present invention will be described. First, dirt such as oil adhering to the surface of concrete is washed with soapy water or acetone, and cracks are buried with putty. Also, the surface irregularities are corrected so as to be smooth with a mortar or putty. Next, in order to improve the adhesion between the concrete and the CFRP, a primer is applied and left for about 24 hours to dry. Then, CFR
A matrix of P, a room temperature curable epoxy resin that is liquid at room temperature is applied and a carbon fiber sheet, for example, a carbon fiber fabric is laminated, and the distribution of the resin is made uniform with an impregnating roller or rubber spatula. To a carbon fiber sheet. Further, a resin is applied thereon, and impregnation operation is performed with an impregnation roller or a rubber spatula, and this is repeated as necessary.

The resin used in the present invention has a viscosity of 30 to
150 poise and a thixotropic coefficient of 3.0 to 3.0
8.0. If the viscosity of the resin is less than 30 poise and the thixotropic coefficient is less than 3.0, when the resin is applied, the uncured resin drips, and the carbon fiber sheet impregnated with the uncured resin is removed from the concrete lower surface. It sags or the carbon fiber sheet attached to the vertical surface slides down. On the other hand, the viscosity of the resin exceeds 150 poise,
When the thixotropic coefficient is larger than 8.0, the resin is applied to the carbon fiber sheet, and even if the impregnating roller is applied, the resin viscosity is high and the applied resin hardly diffuses. Even if it is used, the resin does not sufficiently impregnate the carbon fiber, and the air cannot be released between the concrete and the resin-impregnated carbon fiber sheet or between the laminated resin-impregnated sheets, leaving large voids. Accordingly, not only a sufficient reinforcing effect cannot be obtained, but also cracks are generated from voids due to long-term use, leading to a reduction in the reinforcing effect. Resin viscosity is 30 to 15
0 poise and a thixotropic coefficient of 3.0 to 8.0
In this case, there is no dripping of the resin, no falling or slipping of the resin-impregnated sheet, and a sufficient reinforcing effect is obtained, and the reinforcing effect is not reduced even by long-term use.

Here, the viscosity of the resin is measured according to JIS-K-
6833. That is, using a single cylindrical rotating body, take 500 ml of a sample in a container, confirm that the sample temperature has reached a predetermined temperature, set the rotor of the viscometer at the center of the sample, and rotate it for one minute. Read the scale on the indicator. In this case, the rotation speed of the rotor is set to 20 rotations / minute.
The viscosity is calculated by multiplying a numerical value on a scale indicated by a viscometer by a specified conversion multiplier.

The method of measuring the thixotropic coefficient is the same as the above-mentioned viscosity measurement. However, the rotor used is the same, and the ratio of the viscosity measured while changing the rotation speed of the rotor is called a thixotropic coefficient. That is, the number of rotations of the rotor is set to 20 rotations / minute and 2 rotations / minute, and the thixotropic coefficient is a value calculated by the following equation.

Thixotropic coefficient = (viscosity at 2 rotations / minute) / (viscosity at 20 rotations / minute) The amount of resin applied is 1 to 2.5 times the weight of the carbon fiber sheet.
Double is preferred. Since the viscosity of the resin used is high, it is difficult to uniformly diffuse when applied to the carbon fiber sheet, so if the amount of the resin applied is less than one time the weight of the carbon fiber sheet,
There are places where the resin is insufficient for the carbon fiber sheet, and places where the resin is not impregnated. Further, if it exceeds 2.5 times, even if the viscosity and thixotropic coefficient of the resin,
Even if the sheet conditions such as woven fabric conditions are optimized, the amount of resin is large, so the resin or resin-impregnated sheet drips down, cannot squeeze the resin, and the resin remains between the fabric layers and the concrete surface. After curing, the surface of the CFRP may be uneven. When the amount of the resin applied is 1 to 2.5 times the weight of the carbon fiber sheet, impregnation defective portions do not occur, and the resin or the resin impregnated sheet does not sag and a CFRP reinforced surface having a smooth surface is obtained. Can be

The resin used in the present invention is a thermosetting resin such as an epoxy resin, a vinyl ester resin, an unsaturated polyester resin, or a phenol resin. Among them, the epoxy resin has a large adhesive force to concrete and has a high alkali resistance. It is preferably used because it has excellent adhesion to carbon fibers.

[0042]

【Example】

(Example 1) The number of filaments of a PAN-based carbon fiber having a hook strength of 1600 N of a carbon fiber yarn (cross-sectional area of 0.889 mm ² ) measured according to JIS L 1013 method is 12 2,000 carbon fiber threads with a sizing adhesion of 1.0% are used as warp yarns, weft yarns are made of glass fiber with a cross-sectional area of 0.009 mm ² , weft yarn weave density is 5 yarns / cm, and weft yarns are linear. 1. Copolymer nylon
7 g / m ^2, and the warp carbon fiber yarns were bonded at the intersection of the weft yarns.
A fabric of 03 g / m ² was produced.

Unwinding the woven fabric from the roll on which the woven fabric is wound,
Observation of the attached fluff and broken single fiber of the carbon fiber on the woven fabric surface inside the roll with a stereoscopic microscope revealed that the deposited fluff was 0.05 / cm ² and the number of cut single fibers was 0.10 / c.
m ² was hardly observed. In the above description, on the surface of the woven fabric, the fluff at which both ends of the single fiber were cut was attached to the fluff, and the fluff that was seen from the carbon fiber thread and the single fiber was cut off was the single fiber cut. In addition, when marking is performed on the surface of the woven fabric during such measurement, a piece of single fiber may be broken, so place a piece of paper cut out to 2 × 2 cm on the woven fabric, magnify 25 times with a stereoscopic microscope, and measure 4 cm in area. ^The number of fluffs and broken single fibers generated in 2 was counted. Then, repeating the measurement 5 times, after the average value is obtained, in terms of per a measurement area 1 cm ^2.

Next, the air permeability of the woven fabric was measured according to JIS L
The air permeability was 50 cc / cm ² / sec as measured by a Frazier tester according to the 1096 method.

In order to investigate the state of air entrapment between the concrete and the resin-impregnated carbon fiber fabric during upward molding, a veneer plate temporarily fixed with a polyester film was placed so that the film surface was on the lower surface, and first the resin viscosity was measured. Is 80 poise and resin with thixotropic coefficient of 5.0
00 g / m ² , coated with a rubber spatula so as to be uniform, one carbon fiber woven fabric of the present invention described above was applied, and a grooved impregnating / defoaming roller was applied.
g / m ² of resin was applied, and the resin was impregnated with a grooved roller and defoamed. Further, a 200 g / m ² resin is applied thereon with a rubber spatula so as to be uniform, and the direction of the carbon fiber is the same as that of the first layer.
The second layer of carbon fiber fabric is impregnated with resin and defoamed with a sticking roller, and then 200 g / m ² of resin is applied thereon to impregnate and defoam the resin.
The layers of fabric were laminated. The amount of resin used is 1,30
At 0 g / m ² , it was 1.4 times the weight of the carbon fiber.
Here, a carbon fiber woven fabric cut from a 25 cm width to a 3 m length was used.

The resin did not sag during the application of the resin, and the woven fabric impregnated with the resin did not fall.

The number of fluffs attached to the palms of both hands with a loupe was as small as 5 to 8 and the palms of both hands were rubbed against each other just in case, but no tingling occurred. The number of fuzz attached here was determined by measuring the amount of fuzz attached to three workers.

This was left at room temperature for 3 days to cure the resin, and the state of entrapped air between the polyester film and CFRP was observed. The place where the air is embraced is CFR
Although it became whitish without adhering to P, when this area was measured, it was about 0.5% of the entire area, and air was almost completely released. Then, when a cross section of the CFRP plate, which is perpendicular to the arrangement direction of the carbon fibers, was observed with a microscope, there was no void between the carbon fiber fabrics due to the inclusion of air, and the resin was almost completely filled between the fibers of the carbon fiber fabrics. Had been impregnated.

(Comparative Example 1) Carbon fiber yarn (cross-sectional area 0.914 m) measured according to JIS L 1013 method
m ² ) A PAN-based carbon fiber filament having a hooking strength of 450 N, a filament number of 12,000, and a carbon fiber yarn with a sizing adhesion of 1.0% was used as a warp yarn. As in the example, the basis weight of the carbon fiber is 3
A fabric of 05 g / m ² was produced.

[0050] Observation of the fluff of the textile surface in the same manner as in Example, adhesion fluff 0.30 present / cm ^2, single fiber breakage number is fairly large and 2.75 present / cm ^2.

Next, the air permeability of this woven fabric was measured according to JIS L
The air permeability was 47 cc / cm ² / sec as measured by a Frazier tester according to the 1096 method.

A resin impregnation operation was performed using the same resin as in the example, and the number of fluffs attached to the palms of both hands was measured with a loupe in the same manner as in Example 1. Were rubbed together and were unpleasant.

Observation of the state of entrapped air between the polyester film and the CFRP revealed that the area which appeared whitish was about 0.7% of the entire area, and the air had almost completely escaped. Then, when the cross section of the CFRP plate, which is perpendicular to the arrangement direction of the carbon fibers, was observed with a microscope, there were no voids between the carbon fiber fabrics by embracing air, and also between the fibers of the carbon fiber fabrics. The resin was almost completely impregnated.

[0054]

According to the present invention, by adopting the above-described structure, the generation of fluff is small during the manufacturing process of the sheet or the resin impregnation of the concrete structure, and it is possible to prevent the occurrence of tingling during the resin impregnation work. Therefore, the effect that the workability is excellent is exhibited.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing how to measure the hooking strength of a carbon fiber yarn used in the present invention.

FIG. 2 is a perspective view of a carbon fiber sheet according to one embodiment of the present invention.

FIG. 3 is a perspective view of a carbon fiber sheet according to one embodiment of the present invention.

FIG. 4 is a perspective view of a carbon fiber sheet according to one embodiment of the present invention.

FIG. 5 is a perspective view of a carbon fiber sheet according to one embodiment of the present invention.

[Explanation of symbols]

 1, 2: carbon fiber thread 3: gripping part 4: warp direction carbon fiber thread 5: weft direction auxiliary thread 6: warp direction auxiliary thread 7: weft direction carbon fiber thread 8: support 9: Binder 10: Low melting point polymer A: Between grips B: Carbon fiber thread group C: Auxiliary yarn group in warp direction 2: Auxiliary yarn group in weft direction A: Upper grip distance B: Lower grip distance

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B29K 77:00 105: 08

Claims (12)

[Claims] 1. In a sheet in which a large number of carbon fiber yarns are arranged in parallel, the carbon fiber yarns are JIS L
A carbon fiber sheet having a hooking strength measured according to the 1013 method of 1,000 N or more per 0.9 mm ² in cross-sectional area. 2. The carbon fiber sheet according to claim 1, wherein the carbon fiber yarns are arranged in a warp direction, and auxiliary yarns are arranged in a weft direction so as to cross the carbon fiber yarns. 3. A group of yarns, wherein said carbon fiber yarns constitute a yarn group without being bent substantially, and a weft direction auxiliary yarn group intersecting with said carbon fiber yarns is located on both sides of said yarn group. The carbon fiber sheet according to claim 1, wherein the weft direction auxiliary yarn group and the warp direction auxiliary yarn group parallel to the carbon fiber yarn group form a woven structure and integrally hold the carbon fiber yarn group. 4. The carbon fiber sheet according to claim 1, wherein the sheet is a bidirectional carbon fiber fabric. 5. The carbon fiber sheet according to claim 1, wherein the carbon fiber thread is bonded to a support with a binder. 6. The carbon fiber thread includes a low-melting polymer extending linearly or in a dot-like manner in a length direction thereof, and the low-melting polymer is bonded to a yarn orthogonal to each other at an intersection thereof. 5. The carbon fiber sheet according to any one of 2 to 4. 7. The carbon fiber sheet according to claim 2, wherein the weft direction auxiliary yarn includes a low melting point polymer, and the polymer bonds the carbon fiber yarns to each other at their intersections. 8. The carbon fiber sheet according to claim 2, wherein the auxiliary yarn is glass fiber. 9. The carbon fiber sheet according to claim 6, wherein the amount of the low-melting polymer adhered is 0.5 to 6.0 g / m ² per sheet area. 10. The carbon fiber sheet according to claim 7, wherein the amount of the low-melting polymer adhered to the auxiliary yarn is 50% by weight or less of the weight of the auxiliary yarn. 11. A carbon fiber having a basis weight of 200 to 400 g / m.
^2. The air permeability of the sheet according to JIS L 1096 method is 2
The carbon fiber sheet according to any one of claims 1 to 10, wherein the carbon fiber sheet has a pressure of 0 to 300 cc / cm ² / sec. 12. The carbon according to claim 1, wherein a resin having a thixotropic coefficient of 3.0 to 8.0 and a viscosity of 30 to 150 poise is applied to the surface of the concrete. A method for repairing and reinforcing a concrete structure, comprising laminating fiber sheets, impregnating the carbon fiber sheet with the resin, and curing at room temperature.