JP4268704B2 - Method for detecting the number of FRP layers in reinforced fiber fabrics and concrete structures - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reinforcing fiber fabric constituting a fiber reinforced plastic (hereinafter referred to as FRP) plate used for repairing and reinforcing a concrete structure, and a method for detecting the number of layers of the reinforcing fiber fabric.
[0002]
[Prior art]
Repair and reinforcement with FRP because it is easy to install as a countermeasure against earthquakes and deterioration of concrete structures in the field of civil engineering and architecture, ie bridge piers, girders, floor slabs and pillars of buildings, walls and girders. More and more cases are being made.
[0003]
Reinforcement with FRP plate is performed by laminating a sheet base material made of reinforced fibers such as woven fabric so that the reinforced fibers are arranged in a predetermined direction and in a predetermined amount so that the set mechanical characteristics are obtained. This is done by curing. Since these operations are performed by humans, the substrate stacking direction and the number of layers may be mistaken due to human error. FRP is a material with large anisotropy that is excellent in mechanical properties such as tensile strength and tensile modulus in the direction of reinforcing fibers, but suddenly decreases in mechanical properties when deviated from the direction of fibers. In addition, since the reinforcement effect of the mechanical properties of concrete structures due to reinforcement is governed by the amount of fibers, the direction of reinforcing fibers after reinforcement work, that is, the direction of the base material, especially the number of laminated base materials, is as specified. It is important from the viewpoint of reliability to check whether
[0004]
At present, the direction of the reinforcing fibers and the number of laminated layers are confirmed by a method of confirming by taking a photograph after completing the lamination of one layer and the impregnation work. There is a need to take a huge number of photos and it is cumbersome. In addition, a method of cutting out a sample of the FRP plate at a reinforced location and observing the cross section of the FRP plate, or removing the reinforcing fiber base material by burning the resin portion, and investigating and confirming the number of layers and the fiber arrangement direction However, there is an inefficiency in that the corner reinforced portion must be destroyed and investigated, and there is also a problem that the strength and rigidity of the reinforced portion are lowered during sample collection.
[0005]
[Problems to be solved by the invention]
The object of the present invention is to solve the above-mentioned problems in the prior art and repair and reinforce a reinforced fiber fabric and a concrete structure that can easily detect the laminated state of the base material after being formed into FRP with an FRP plate. It is to provide a method for detecting the arrangement direction, the number of stacked layers, and the number of laminated reinforcing fibers of the base material.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the reinforcing fiber woven fabric of the present invention is a sheet of a yarn group in which reinforcing fiber multifilament yarns that do not have a bending in which stress is concentrated are drawn in parallel in one direction and in a sheet shape. Weft-direction auxiliary yarn groups are located on both sides, and the weft-direction auxiliary yarn groups and the warp-direction auxiliary yarn groups parallel to the reinforcing fiber multifilament yarns form a woven structure to hold the yarn groups together and are adjacent to each other. There is a gap of 0.3 to 2 mm between the reinforcing fiber yarns, and metal wires are inserted into the fabric surface with a spacing of 30 to 100 cm .
[0007]
The method for detecting the number of laminated reinforcing fiber fabrics according to the present invention is a method for detecting the number of laminated reinforcing fiber fabrics, wherein a resin is applied to the concrete structure surface, and then a sheet-like reinforcing fiber fabric is applied. At the same time, the reinforcing fiber fabric is impregnated with a resin and cured at room temperature to form FRP, thereby reinforcing the concrete structure, and then detecting the number of layers of the reinforcing fiber fabric, the reinforcing fiber fabric according to the present invention. A plurality of metal wires are inserted so that the insertion positions of the metal wires are different from each other , and after impregnation with the resin , the resin is cured to reinforce the concrete structure, and then the reinforcing fiber fabric is detected by sensing the insertion location of the metal wires. The method comprises detecting the number of stacked layers.
[0008]
Metal wire sensing according to the present invention is
(1) Sense by introducing a metal wire into an alternating magnetic field and disturbing the magnetic field,
(2) A metal wire generates heat by electromagnetic induction, and the heat generation part is detected by an infrared radiation thermometer.
It consists of the method characterized by either.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0010]
In explaining the method for detecting the number of laminated reinforcing fiber fabrics according to the present invention, first, impurities such as oil adhering to the concrete surface are removed with an organic solvent such as acetone or soapy water, and cracked or chipped portions of the concrete. Resin and mortar are filled in, and the convex part of the concrete is shaved to smooth the adhesion surface. In order to improve the adhesion between the concrete surface and the FRP plate, an epoxy resin primer having a low viscosity is applied and left for about 1-2 days until the primer resin is cured. Next, a resin serving as an FRP matrix is applied onto the primer with an application roller, and a reinforcing fiber fabric in which reinforcing fibers are arranged in parallel in the length direction is laminated in a predetermined direction. The foam is defoamed simultaneously with the resin impregnation into the fabric and cured at room temperature. Similarly, reinforcing fiber fabrics are further laminated in a predetermined direction, and after applying resin, rolling with a roller, impregnating and defoaming the resin, and curing at room temperature, forming an FRP layer on the concrete surface, a concrete structure Reinforce. Depending on the degree of reinforcement, these laminating operations are repeated to increase the number of laminated layers, that is, the amount of reinforcing fibers.
[0011]
The above is a method for repairing and reinforcing a concrete structure by FRP which is usually performed, and there is no change in the present invention. However, in the present invention, the reinforcing fiber woven fabric in which the metal wire is inserted in the above is used as a metal. Lamination is performed so that the insertion point of the line is different in each layer.
[0012]
FIG. 1 is a schematic view showing an example of a reinforced fiber fabric 1 having a metal wire inserted therein according to the present invention. The woven fabric of the present invention will be described with reference to FIG. 1. A reinforced fiber multifilament yarn obtained by aligning reinforced fiber multifilament yarns 2 having no bending at which stress is concentrated in a sheet shape in parallel in one direction. A group of warp direction auxiliary yarns 3 in parallel with the reinforcing fiber multifilament yarn, and a weft direction of the weft direction auxiliary yarns 4 group C located on both sides of the sheet surface. Two metal wires 5 are arranged on the front and back surfaces of the woven fabric, and the warp direction auxiliary yarn group B, the weft direction auxiliary yarn group C and the metal wire form a woven structure, and the yarn group A is integrated. Is held in. Further, there is a gap A between adjacent reinforcing fiber multifilament yarns, and the intersection of the warp yarn and the weft yarn is bonded to the low melting point polymer 6 to prevent yarn misalignment by the resin impregnated roller or the like, that is, misalignment. Yes.
[0013]
Such a unidirectional woven fabric has a so-called non-crimp structure in which the reinforcing fiber multifilament yarns 1 are arranged straight without bending, so that stress concentration does not occur even if it is hardened with resin. The tensile strength and tensile modulus of
[0014]
In the above, two metal wires are aligned at one place and inserted twice, that is, four wires are inserted, but one metal wire may be provided at one place.
[0015]
FIG. 2 shows a state in which the metal wires 5 are arranged in the transverse direction at intervals in the length direction of the reinforcing fiber fabric 1 of the present invention, but arranged at intervals of pitch B in the length direction of the fabric. Has been.
[0016]
Reinforcing fibers used in the fabrics of the present invention, carbon fibers, polyaramid fibers, although glass fiber, among others carbon fibers excellent in耐A Le potash resistance, tensile strength, of the concrete structure is excellent in tensile modulus It is preferably used for repair and reinforcement. In addition, since the woven fabric can be manufactured at low cost, the fineness of the reinforcing fiber multifilament yarn is preferably about 3,000 denier to 30,000 denier.
Yes.
[0017]
The auxiliary yarns in the warp direction and the weft direction are preferably glass fibers or polyaramid fibers in order to prevent heat shrinkage when melting a low melting point polymer yarn such as copolymer nylon by heating. Moreover, since the auxiliary yarn is not essentially used as a reinforcing fiber but is used for forming a woven fabric, the fineness is preferably about 100 to 1,300 denier.
[0018]
The gap A between the reinforcing fiber multifilament yarns is preferably 0.3 mm to 2 mm. The resin used for repair and reinforcement is an epoxy resin with a high viscosity for hand lay-up molding with a room temperature curing type viscosity at 25 ° C. of 30 to 200 poise from the viewpoint of preventing dripping of the resin and sliding of the fabric. It is used. For example, after applying an undercoat resin to a concrete surface, applying a woven fabric and applying an overcoat resin, the undercoat resin passes through the woven fabric and moves to the overcoat resin side even if it is hung or rolled. do not do. Therefore, the undercoat resin remains between the concrete surface and the woven fabric, and traces of slap and roller hang remain due to the excess resin, and the surface of the FRP after curing becomes uneven, resulting in poor appearance. For this reason, the gap is preferably 0.3 mm or more. On the other hand, when the gap is large, the interval at which the reinforcing fiber yarns can be arranged relatively becomes small, so that only a woven fabric having a small basis weight of the reinforcing fibers can be obtained. Further, when the conventional carbon fiber basis weight to 300g / m ² ~400g / m ² about fabric, since would be caused to the reinforcing fiber yarns are arranged in a closely spaced, larger array density of filaments of reinforcing fibers Since the impregnation of the resin into the reinforcing fiber yarn is hindered, 2 mm or less is preferable.
[0019]
The arrangement direction of the metal wires is described in FIG. 1 as an example in which the metal wires are arranged in the transverse direction, but may be arranged in the vertical direction. However, since it is necessary to stack the metal wires while shifting the position to detect the number of layers after making the FRP, if you arrange them in the vertical direction, you must prepare many types of fabrics with different insertion positions. In addition, textile manufacturing and lot management become troublesome. On the other hand, in the case of a woven fabric in which metal wires are arranged at regular intervals in the weft direction, it is only necessary to cut the metal wire insertion points so as to be shifted by a predetermined interval when laminating with one type of woven fabric. Since the fabric can be automatically manufactured by the operation of the dobby, the manufacture of the fabric is simple, and there is no need for lot management.
[0020]
FIG. 3 is a partially broken schematic diagram for explaining an example of a metal wire detection method in a state where the reinforcing fiber fabric 1 of the present invention is laminated on the surface 8 of the concrete structure 7 and becomes FRP.
[0021]
In FIG. 3, four layers of the reinforcing fiber fabric 1 of the present invention are laminated on the concrete surface 8 so that the directions of the reinforcing fibers are the same, and impregnated with a matrix resin to be in an FRP state. Fabric ₁ 1 of the first layer in the FRP, 2-layer fabric 1 _2, 3-layer fabric 1 ₃ and fourth layer of fabric 1 ₄ of the metal wire 5 _1, 5 _2, 5 ₃ and 5 ₄ are equally spaced Are stacked so as to be shifted by C. If this distance C is too small, the metal lines in each layer cannot be discriminated when detecting the metal lines . Further, the gap C between the metal lines of each layer in the FRP does not necessarily have to be equal, but it is preferable that the gap is equal because the number of detection lines is not mistaken at the time of detection.
[0022]
The pitch P of the metal wire insertion location in the woven fabric of the present invention varies depending on the number of stacked layers and the shift interval B when the layers are stacked, but the pitch P is 30 to 100 cm, and the metal wires have an interval of 30 to 100 cm. Inserted into the fabric surface . In metal line detection, if the metal lines of all the layers are stacked so that the metal lines of the metal lines are arranged one by one in the pitch P of the metal line arrangement, the number of metal line insertion positions detected in the pitch P is the number of layers. I can do it.
[0023]
By moving the sensor 9 of the detection device in the upper part of the FRP where the metal wire is present or installing the sensor 9 of the detection device and grasping the insertion position of the metal wire embedded in the FRP, The number of stacked layers can be detected nondestructively.
[0024]
The metal wire sensing of the present invention
Method A: A method in which a metal wire is introduced into an alternating magnetic field and the magnetic field is disturbed,
Method B: A method in which a metal wire generates heat by electromagnetic induction, and the heat generation part is detected by an infrared radiation thermometer.
It is preferable to carry out either of these.
[0025]
Next, the detection method of the present invention will be described.
[0026]
FIG. 4 and FIG. 5 are schematic diagrams for explaining an example of the principle of the method A used by the detecting means. As shown in FIG. 5, when an FRP metal wire 5 enters while the balanced primary magnetic field 12 is formed by the oscillator 10 and the excitation coil 11 as shown in FIG. An induced current flows through 5. Due to this induced current, a secondary magnetic field 15 is generated around the metal wire, disturbing the balanced magnetic field. Due to this disturbance, a minute voltage is induced in the magnetic receiving coil 13, and the detector 14 detects this voltage and can detect the presence of the metal wire.
[0027]
For the detection of the number of laminated fabrics, a detector is placed on the surface of the FRP, and the detector is placed in a direction perpendicular to the arrangement direction of the metal wires by the pitch P of the metal wire insertion position on the substrate, that is, by a distance of one cycle. While moving, the number of times during which the detection device senses the insertion point of the metal wire is counted. The number of times the metal wire insertion point is detected is the number of FRP layers.
[0028]
Examples of the detection device used in this method include a metal detector and a proximity switch. Since these devices are small and light, they are easy to handle and can be used even in places where detection is difficult, such as high places and narrow parts.
[0029]
The detection means of the B method, that is, the detection means is an infrared camera, and a method of heating a metal wire by electromagnetic induction and detecting the heat generation portion with an infrared radiation thermometer will be described.
[0030]
In this method, a metal wire of FRP is put in a magnetic field generated by a current flowing through a coil of an induction heating device, an eddy current is caused to flow through the metal wire, and Joule heat is generated in the metal wire by this eddy current. Heat. This heat generation portion can be detected by an infrared radiation thermometer, and the position of the metal wire can be detected. Note that, as time passes, heat is transferred into the FRP and diffuses to lower the temperature of the metal wire. Therefore, it is preferable to perform the detection operation with the infrared radiation thermometer immediately before the temperature decreases.
[0031]
In this method, when the heated portion is observed using an infrared radiation thermometer, the heated portion appears in a linear shape. Therefore, from the total number of the heated portions within one cycle interval of the metal wire arrangement on the sheet material, Can be detected.
[0032]
The infrared radiation thermometer, which is a detection means of the method B, detects infrared radiant energy self-radiated from a measurement object, and finally displays it as a color or black-and-white thermal image. There is an infrared camera or the like, but if it has such a function, it is not specified.
[0033]
Note that the B method can detect a metal wire in a linear form, and therefore can easily detect not only the number of layers but also the direction of lamination.
[0034]
Metal wire for use in the present invention, since it is easily magnetized by the magnetic field, iron detection becomes easy, nickel, and their alloys, as well as chromium oxide IV (CrO ₂₎ wire ing a ferromagnetic material such as Among them, iron wire is preferable because it is inexpensive.
[0035]
However, if the cross-sectional area of the metal wire at the insertion point is small, it is difficult to detect, and if it is too thick, the rigidity of the metal wire will be high and it will be difficult to unite with the sheet material, and the insertion point will rise to a convex shape. It is not preferable. Therefore, the metal wire is preferably inserted so that 2 to 4 sheet materials are in parallel with a single wire having a cross-sectional area of 0.005 to 0.07 mm ² or less.
[0036]
In the present invention, carbon fiber is used as the reinforcing fiber, and the electric current flows because the electric potential of the metal wire and the carbon fiber is different, and the metal wire is rusted by electric corrosion, which adversely affects the discoloration and physical properties of the carbon fiber reinforced plastic. Therefore, it is preferable to provide an insulating coating around the metal wire. In particular, when the coverage is 100%, the prevention of electrolytic corrosion may be ensured.
[0037]
As the insulating coating material, a fibrous material that permeates the resin is preferable, and this is preferably wound around the metal wire. For example, as the covering material, there are fiber filament yarns such as polyester, nylon, glass, vinylon, etc., which can be covered by winding them around a metal wire as a core material by a covering method or a string manufacturing method.
[0038]
Examples thereof include fibers such as polyester, nylon, glass, vinylon, polypropylene, and polyaramid. However, the role of the material is not particularly limited because the role of the material is to ensure insulation. However, it is preferable to select one having a low water absorption rate because of its good adhesion to the matrix resin and prevention of electric corrosion. In addition, when the covering material is colored red or green, it is easy to set the amount of deviation of the metal wire in the lamination of the sheet material while visually observing, and the lamination work can be performed efficiently.
[0039]
【Example】
Example 1
An iron wire having a diameter of 0.11 mm is used as the metal wire, and a 75 denier polyester filament yarn is wound in the S direction on this iron wire, and then a 100 denier low melting point nylon yarn is wound 1,000 times / m in both the Z direction. An iron wire with an insulation coating having a coverage of 100% was prepared.
[0040]
Subsequently, the reinforcing fiber fabric of the present invention was produced as follows.
[0041]
Carbon fiber multifilament yarn in the warp direction (number of single yarn: 24,000, fineness: 14,400 denier, tensile strength 4,900 MPa, tensile elastic modulus 230 GPa) and glass fiber yarn (405 denier) as the auxiliary yarn in the warp direction ) Are alternately arranged at a density of 1.88 / cm, and in the weft direction, covering yarn in which 203 denier glass fiber is coated with 50 denier low melting point nylon yarn is used as auxiliary yarn in the weft direction. Driving at a density of 5 wires / cm, stopping the driving of auxiliary yarns for 2 picks at an interval of 50 cm, aligning the two covered iron wires and driving a total of 4 iron wires (insertion length of one metal wire) 2mm), and then, after inserting the auxiliary yarn and repeating this, while inserting the coated iron wire at intervals of 50 cm in the weft direction, the heater wire attached to the loom was used to cut off the iron wire. By melting the low-melting nylon thread and a low-melting nylon thread of auxiliary yarn used for the coating, by adhering the auxiliary yarn and vertical auxiliary yarns and carbon fibers in the transverse, eyes etc. rice. A carbon fiber multifilament yarn having an interval of 50 cm, that is, an arrangement period of 50 cm and a carbon fiber basis weight of 300 g / m ² and a carbon fiber basis weight of 300 g / m ² is arranged straight, and a gap between the carbon fiber yarns is 0.5 mm. An inventive unidirectional carbon fiber fabric was prepared.
[0042]
Next, in preparation for lamination, four sheets were cut so that the positions of the metal wire insertion positions were shifted by 5 cm with the weft direction of the fabric aligned.
[0043]
Next, 400 g / m ² of room temperature curing epoxy resin having a viscosity of 55 poise at 25 ° C. was applied as an undercoat to the concrete surface of the pier that had been coated with a primer and left for a day and night. Then, 200 g / m ² of epoxy resin is applied as an overcoat on the fabric, and then the fabric is impregnated with an impregnation roller, and then 200 g / m ² of resin is applied, and then the second layer fabric is formed. On the first layer, the weft direction of the fabric was aligned and adhered in the circumferential direction of the pier, and the resin was applied in the same manner as the first layer, and the fabric was impregnated with the impregnation roller. Similarly, the third and fourth layers were laminated, the resin was applied, and the resin was impregnated and cured at room temperature, and the concrete surface was reinforced with a laminate, that is, a carbon fiber woven FRP.
[0044]
Since there is a gap between the carbon fiber yarns of the woven fabric, when the resin impregnation roller is applied to the woven fabric of each layer, the resin of the undercoat is released from the gap between the carbon fiber yarns of the woven fabric without the extra resin being partially unevenly distributed. As a result, the surface of the cured FRP was smooth.
[0045]
For detection of the metal wire, a proximity switch having a sensor outer diameter of φ30 was used as a metal detector. In this device, when a metal was detected, the lamp was turned on, and this was placed on the surface of the FRP. Next, the switch was moved at a speed of 2 m / min in a direction perpendicular to the longitudinal direction of the metal wire, and the switch was stopped when moved by 50 cm. When the number of times the lamp was turned on during this movement was measured, it was 4 times, and it was confirmed that the number of stacked layers was 4.
[0046]
Since the carbon fiber is black, the laminated body also becomes black, and the presence of the metal wire cannot be visually recognized from the appearance, but the proximity switch can detect the number of laminated layers without destruction.
[0047]
(Example 2)
FRP affixed to the same concrete as Example 1 was heated with a 100V, 1400W electromagnetic induction device for 1 minute, then the electromagnetic induction device was removed and measured with an infrared radiation thermometer installed at a distance of 1 m from FRP. did. As the infrared radiation thermometer, an HgCdTe detector having a minimum detection temperature difference at 30 ° C. of 0.08 ° C. and a temperature measurement range of −50 to 2000 ° C. was used.
[0048]
When the temperature distribution was displayed as a color thermal image, four high temperature portions that were elongated in the length direction of the pier were observed, and it was detected that the number of layers was four.
[0049]
【The invention's effect】
The reinforced fiber fabric of the present invention can easily detect the number of FRP laminations and the lamination direction that cannot be detected by a normal nondestructive inspection method. Further, according to the method for detecting the number of layers of the present invention, the number of FRP layers in the concrete structure and the direction in which the layers are stacked can be easily detected in a nondestructive manner.
[Brief description of the drawings]
FIG. 1 is a view illustrating a unidirectional reinforcing fiber woven fabric in which metal wires are arranged in parallel with the width direction of the woven fabric according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a state in which the fabric is inserted in the length direction according to an embodiment of the present invention.
FIG. 3 is a diagram for explaining a metal line arrangement state and a state of detection of the number of stacks in a stacked body according to an embodiment of the present invention.
FIG. 4 is a diagram for explaining the principle of sensing a metal wire according to one embodiment of the present invention, and for explaining that a magnetic field is in an equilibrium state.
FIG. 5 is a diagram for explaining the principle of metal wire sensing according to one embodiment of the present invention, and is a diagram for explaining that a metal wire enters a magnetic field and is in an unbalanced state.
[Explanation of symbols]
1: Reinforcing fiber fabric 2: Reinforcing fiber multifilament yarn 3: Warp direction auxiliary yarn 4: Weft direction auxiliary yarn 5: Metal wire 6: Low melting point polymer 7: Concrete structure 8: Structure surface 9: Sensor 10: Oscillator 11: Excitation coil 12: Primary magnetic field 13: Receiving coil 14: Detector 15: Secondary magnetic field

Claims (5)

A reinforcing fiber fabric satisfying the following requirements (A) to (C):
(A) There is a lateral direction auxiliary yarn group located on the sheet both sides of the yarn group in which reinforcing fiber multifilament yarns that do not have a bend in which stress is concentrated are aligned in one direction and parallel to each other in a sheet shape. The weft direction auxiliary yarn group and the warp direction auxiliary yarn group parallel to the reinforcing fiber multifilament yarn form a woven structure to hold the yarn group integrally,
(B) Between the adjacent reinforcing fiber multifilament yarn has a gap of 0.3-2 mm,
(C) And the metal wire is inserted in the fabric surface with an interval of 30 to 100 cm . The reinforcing fiber fabric according to claim 1, wherein the reinforcing fiber multifilament yarn is a carbon fiber, and the metal wire is covered with an insulating coating. The method for detecting the number of laminated reinforcing fiber fabrics according to claim 1 or 2 in a concrete structure satisfying the following requirements (a) and (b).
(A) After laminating a plurality of the reinforcing fiber fabrics according to claim 1 or 2 so that the insertion positions of the metal wires are different from each other by 2 cm or more , after impregnating the resin, curing the resin and reinforcing the concrete structure ,
(B) The number of layers of the reinforcing fiber fabric is detected by sensing the metal wire. Introducing the metal wire in the AC magnetic field, the reinforcing fiber woven fabric according to claim 1 or 2 in the concrete structure according to claim 3, characterized by detecting the metal wire by disturbing the magnetic field A method for detecting the number of stacks. The metal wire is heated by electromagnetic induction, according to claim 1 or 2 in the concrete structure according to the heat generating portion to claim 3, characterized by detecting the metal wire by detecting the infrared camera A method for detecting the number of laminated reinforcing fiber fabrics.

Images