JP4078726B2 - Multilayer reinforced fiber sheet and structure repair / reinforcement method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reinforcing fiber sheet and a method for repairing and reinforcing a structure.
[0002]
[Prior art]
Concrete structures such as bridge slabs, piers, tunnels, chimneys and buildings have been deteriorated due to neutralization and rust generation due to long-term use, increased load due to reduced weight restrictions on passing vehicles, damage due to earthquakes In addition, repairs and reinforcements have become necessary due to revisions of seismic standards for large earthquakes.
[0003]
Recently, since repair and reinforcement of these structures are easy to construct, a so-called hand lay-up method, in which a sheet made of reinforcing fibers is attached to the structure and impregnated with a room temperature curable resin, has attracted attention. In this method, the resin is completely cured at room temperature in about one week, and a reinforced plastic plate is formed on-site, and the reinforced plastic (hereinafter referred to as FRP) plate and the structure are bonded at the same time. Construction is simplified.
[0004]
However, the repair / reinforcement part of the structure also includes vertical surfaces such as ceiling surfaces such as the bottom of floor slabs, piers, and pillars of building structures. If resin is applied to these ceiling surfaces or vertical surfaces, the resin will drip off. Since a predetermined amount of resin cannot be applied, the viscosity of a resin that is usually used to prevent these is as high as 2,000 to 25,000 mPa · s (millipascal × second). Usually, the hand lay-up molding method is often used as a molding method for boats and tanks, but the viscosity of the room-temperature-curable unsaturated polyester resin and vinyl ester resin used here is the reinforcement that constitutes the sheet. From the viewpoint of resin impregnation into the fiber, it is 200 to 500 mPa · s, and at most about 1,000 mPa · s. Compared to this, the viscosity of the resin used for repairing and reinforcing the structure is extremely high, and the resin impregnation property to the reinforcing fiber is not so good.
[0005]
Therefore, the reinforcing fiber sheet frequently used for repair and reinforcement of structures is thin, the reinforcing fiber is made of carbon fiber, and the basis weight of carbon fiber is 200 to 300 g / m.²That is, the volume of carbon fiber per square meter is 110-170 cm^ThreeIt is a thin reinforcing fiber sheet in which carbon fibers are arranged in one direction.
[0006]
Therefore, the number of reinforcing fiber sheets to be used is increased in order to cope with the amount of reinforcing fibers necessary for repairing and reinforcing the structure, and resin impregnation work is required for each sheet. It is troublesome.
[0007]
On the other hand, if the amount of reinforcing fiber per sheet is simply increased, the reinforcing fiber yarns constituting the sheet are arranged densely, the degree of focusing becomes large, the fiber interval is clogged, and resin impregnation becomes difficult.
[0008]
[Problems to be solved by the invention]
The present invention pays attention to such a current situation, provides a multilayer reinforcing fiber sheet having a large amount of reinforcing fibers per sheet and excellent in resin impregnation properties, and a method for repairing and reinforcing a structure excellent in workability. The purpose is to provide.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention basically has the following configuration. That is, “the sheet base material in which the reinforcing fiber yarns are arranged in parallel in the length direction of the sheet is laminated in multiple layers so that the directions of the reinforcing fibers are the same, and adjacent layers are integrated with each other.The bulk density of the reinforcing fiber (the volume of the sheet / the volume of the reinforcing fiber) is 220 to 300%.A multilayer reinforcing fiber sheet characterized by that. Is.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The partially broken perspective view which shows the concept of the multilayer reinforcing fiber sheet 1 of this invention was shown in FIG. First layer base material 3 in which a number of reinforcing fiber yarns 2 are arranged in parallel in the longitudinal direction of the sheet₁And base material 3 of the second layer₂Are overlapped so that the directions of the reinforcing fibers are the same, and the base material 3₁And base material 3₂Are integrated with each other by an integration means (not shown in FIG. 1) such as a woven structure or adhesion.
The bulk density of the multilayer reinforcing fiber sheet of the present invention is in the range of 220 to 300%. When the bulk density is 220% or less, the arrangement density of the reinforcing fibers forming the fiber sheet is increased, that is, the gap between the single fibers is reduced, so that the resin impregnation property is deteriorated, and a high viscosity resin is obtained by the hand lay-up method. It becomes difficult to prevent air from being entrapped when impregnating. In addition, when the bulk density is 300% or more, there is no problem of resin impregnation property or air entrapment, but since the sheet fibers are bulky, the amount of resin necessary to fill between the sheet fibers Will increase. Also, by applying resin and removing the impregnation roller, it is possible to hold the bulky sheet and reduce the amount of resin, but the pressed sheet is restored to its original bulky state, that is, the spring back phenomenon Therefore, the amount of resin relative to the recovered sheet is insufficient, and the FRP in which the resin is cured is in a state where a lot of voids are contained.
The bulk density V in the present invention refers to a value calculated by the following calculation formula.
V = A × t ÷ (w / ρ) × 100 (%)
Where t: thickness of the multilayer reinforcing fiber sheet (cm)
A: Fabric area (cm ² )
w: Weight of reinforcing fiber sheet in area A of the fabric (g)
ρ: density of reinforcing fiber (g / cm ^Three )
Here, the measurement method of the sheet thickness is JIS R 7602 The thickness measuring instrument of Section 5.6 conformed to the dial gauge method. However, the load was 50 kPa, the value after 20 seconds had elapsed since the load was applied to the sheet was read and divided by the number of sheets to obtain the thickness per sheet. If the sheet is a woven fabric, measure the thickness by stacking several sheets so that the position of the overlapping auxiliary yarns is shifted from each other so that the influence of the weft auxiliary yarn on the sheet thickness is minimized. Then, the thickness per sheet was determined by dividing by the number of stacked sheets.
  Note that the number of layers is not necessarily two, and may be three or four, and is not limited.
[0011]
The multilayer reinforcing fiber sheet of the present invention can be classified according to the form of the base material and the integration means for obtaining a multilayer structure.
[0012]
First, in order to explain the case where the integration means is based on adhesion, FIGS. 2 to 4 show the form of the base material constituting the multilayer reinforcing fiber sheet of the present invention.
[0013]
FIG. 2 shows that the reinforcing fiber yarns 2 are arranged in the length direction of the base material, that is, the warp direction of the woven fabric, the auxiliary yarns 4 thinner than the reinforcing fiber yarns are arranged in the weft direction, and the warp yarns 2 and the weft yarns 4 are crossed. And a unidirectional woven fabric. FIG. 3 shows that the reinforcing fiber yarns 2 and the auxiliary yarns 5 are oriented in the longitudinal direction of the substrate, that is, the warp direction of the woven fabric, the auxiliary yarns 4 are oriented in the weft direction, and the auxiliary yarns 4 of the weft yarns assist the warp yarns. This is a so-called unidirectional non-crimp fabric in which the reinforcing fiber yarns 2 intersect with the yarns 5 and are straightly oriented without intersecting with the weft yarns 4. FIG. 4 shows a thermoplastic resin in which a sheet of reinforcing fiber yarns 2 in which reinforcing fiber yarns are straightly arranged in parallel in one direction and a mesh-like support 6 are present on the surfaces of adhesives or mesh wires 7 and 8. A tow sheet fused and integrated with a polymer. The mesh-like support 6 is not necessarily limited to two directions of wires orthogonal to each other, but only in one direction of the weft direction, or in three directions oriented ± α ° with respect to the length direction and the reinforcing fiber yarns. There may be. The base material may be a unidirectional knitted fabric in which reinforcing fiber yarns arranged in one direction are knitted with thin auxiliary yarns.
[0014]
Substrates having these forms have been used so far in repairing and reinforcing structures, and are not particularly new.
[0015]
The multilayer reinforcing fiber sheet of the present invention is obtained by superposing and integrating a large number of these substrates. FIG. 5 is a partially broken perspective view of an example of the multilayer reinforcing fiber sheet of the present invention. A multilayer reinforcing fiber sheet in which two unidirectional woven fabrics as a base material are overlapped by an adhesive means, and the base material 3 of the first layer₁And base material 3 of the second layer₂The layers are bonded with a dotted adhesive 9.
[0016]
In order to bond them in the form of dots, a hot-melt thermoplastic resin powder is used as the base material 3₁Sprinkle evenly and uniformly on one side of the substrate 3₂And base material 3 by heating and melting the thermoplastic resin₁And base material 3₂Can be glued.
[0017]
Moreover, the adhesion state of the adhesive may be linear. When weaving the woven fabric, the polymer yarn and weft yarn made of a heat-melting thermoplastic resin are aligned and weaved into the woven fabric, and the warp yarn and weft yarn are bonded by melting the polymer yarn. A so-called fine-mesh fabric is produced. The base material 3 is formed by stacking the woven fabrics and heating again to melt the polymer yarn or more to melt the polymer, and pressurizing as necessary.₁And base material 3₂Can be glued. Moreover, the base material 3₁And base material 3₂It can also be obtained by interposing a large number of polymer yarns in the substrate between the two and heating the polymer yarns more than melting to melt the polymer. In addition, a mesh-like material to which an adhesive having adhesiveness at normal temperature is attached is used as the base material 3₁And base material 3₂It can also be bonded by interposing between them.
[0018]
As described above, it is preferable that the adhesive adheres to the base material in the form of dots or lines because the adhesive does not hinder the resin impregnation. Is preferable because it can prevent misalignment of reinforcing fiber yarns and weft yarns. In addition, the adhesion between the substrates is a thin 5-15 g / m made of a thermosetting resin in a B-suge state between the layers of the substrates.²You may make it interpose a certain amount of film. Alternatively, a thermoplastic resin or thermosetting resin solution dissolved with a diluent is used as the base material 3.₁By spraying on the substrate and drying the diluent 3₂It can also be glued.
[0019]
The impregnation property of the resin is closely related to the sheet air flow rate according to JIS L 1096 method, and the air flow rate is 40 to 300 CC / cm.²It was found that / sec was preferable.
[0020]
Aeration rate of 40CC / cm²If it is less than / sec, the bulk density of the carbon fibers forming the reinforcing fiber yarn is reduced, that is, the space formed by the carbon fibers is small, and the gap between the reinforcing fiber yarns is small, so that the resin impregnation Poor and generates voids.
[0021]
300CC / cm²/ Sec, because the woven fabric has a large gap between the reinforcing fiber yarns, the thickness of the reinforcing fiber portion is increased, the surface is uneven, and the reinforcing fiber yarns are tightly bundled, so that the reinforcing fiber yarns are firmly focused. There is a problem that the impregnation property of the resin decreases.
[0022]
The measurement of the air flow amount was in accordance with the air permeability A method of JIS L 1096 method 6.27.
[0023]
That is, one end of the cylinder is 38.3 cm²  Attach a 20cm x 20cm sheet test piece to the ventilation hole in the prescribed manner, adjust the suction fan so that the tilt type barometer shows a pressure of 1.27cm water column with an adjustable resistor, and the vertical barometer at that time shows From the pressure and the type of air hole used, the amount of air that passes through the sheet specimen (CC / cm) according to the conversion table attached to the tester²/ Sec) and the average value of the five measurement results was defined as the air flow rate.
[0024]
The sample was allowed to stand for 24 hours in a room with a temperature of 20 ° C. and a humidity of 65%, and then measured in that atmosphere. In Examples to be described later, Frazier type tester AP-360 manufactured by Daiei Kagaku Seisakusho Co., Ltd. was used as an air flow rate measuring device.
[0025]
Examples of the thermoplastic resin used for bonding the substrates of the present invention include nylon, copolymer nylon, polyester, copolymer polyester, vinylidene chloride, vinyl chloride, polyeletane, polyethylene, polypropylene, polyvinyl alcohol, acrylic, etc. Copolymer nylon that melts at a low melting point of about 70 to 160 ° C. is preferable because heating and pressure-bonding operations for integration are simple and adhesion is good.
[0026]
The thermosetting resin used for bonding the substrates of the present invention is an epoxy resin, a vinyl ester resin, an unsaturated polyester resin, a phenol resin, or the like, preferably a reinforcement using the multilayer reinforcing fiber sheet of the present invention. -When the impregnation resin used for the reinforcing method is the same as that for the impregnation resin, that is, when the impregnation resin is an epoxy resin, the thermosetting resin used for adhesion may be an epoxy resin. Examples of adhesives that are sticky at room temperature include styrene / butadiene rubber, polyisobutylene, ethylene / vinyl acetate copolymer, acrylic, and vinyl acetate copolymer.
[0027]
The adhesive used for bonding the substrates of the present invention need not essentially be a resin for impregnating the reinforcing fiber resin. Also, the degree of adhesion between the substrates does not need to be strong, as long as the adhesion between the substrates does not peel off during handling, so the amount of adhesive used for adhesion between the substrates should be as small as possible. Well, 2-15g / m²Degree. 15g / m²If it becomes above, the resin impregnation to the multiple reinforcing fiber sheet will be hindered, or the adhesion between the resin for impregnation and the adhesive will be unfavorable.
[0028]
The embodiment of the multilayer reinforcing fiber sheet of the present invention shown in FIG. 5 shows an example of a unidirectional woven fabric as a base material, but the unidirectional non-crimp woven fabric shown in FIG. 3 and the tow sheet shown in FIG. Or a combination thereof.
[0029]
Moreover, it is preferable that the multilayer reinforcing fiber sheet of this invention has a moderate clearance gap between the base materials of an adjacent layer. In the integration by the above-described adhesion, a mesh-like material may be interposed between the base material and the base material. Mesh material is substrate 3₁And base material 3₂Between the substrate 3 and the resin impregnated roller.₁(Or 3₂) Passes through the gaps of the thick mesh material, that is, there is an uncured resin layer between the layers.₂(Or 3₁The resin impregnation becomes easy even if the fiber sheet is thick. The mesh-like material has the wire oriented in two or three directions, and a preferred thickness is 0.1 to 0.4 mm. If the thickness is too large, a large amount of resin exists between the substrates, that is, the amount of resin used increases, resulting in an increase in cost and uneconomical.
[0030]
Further, the multilayer reinforcing fiber sheet of the present invention may be a so-called unidirectional multiple woven fabric in which reinforcing fiber yarns overlap with each other and are integrated by a woven structure by crossing of auxiliary yarns orthogonal to the reinforcing fiber yarns. . FIG. 6 is a cross-sectional view showing a double woven fabric as an example of a unidirectional multi-woven fabric. In the drawing, reinforcing fiber yarn 2₁And auxiliary thread 4₁Plain fabric 3 consisting of₁And reinforcing fiber yarn 2₂And auxiliary thread 4₂Plain fabric 3 consisting of₂It has a multilayer structure. And plain fabric 3₁A part of auxiliary thread 4₁And plain fabric 3₂Reinforcing fiber yarn 2₂Plain fabric 3 by crossing with each other₁And plain fabric 3₂Are held together.
[0031]
When the woven structure is integrated as described above, since it is not necessary to use an adhesive or the like for the integration, the impregnation of the resin is not hindered. Plain fabric 3₁And plain fabric 3₂A gap A is formed between the plain fabric 3 and the impregnated roller.₁High-viscosity resin is plain fabric 3₁Resin impregnation is performed. In addition, since the amount of resin more than the required amount is usually applied so that the resin spreads over the entire surface of the sheet, excess resin, concrete, and fabric 3₁The air that existed between them was the fabric 3₁The air substituted with the internal resin moves to the gap A part. Textile 3₁Does not embed air with concrete, and weaving 3₁Resin impregnation is performed. Next, the resin stored in the gap A is plain fabric 3₂From the bottom of the fabric 3₂Impregnated inside and plain fabric 3₂The fabric 3 is also made of resin applied to the upper surface of the fabric.₂Therefore, the impregnation property is not hindered by the high weight of the reinforcing fiber.
[0032]
When weaving multiple woven fabrics, the auxiliary yarn and the low-melting polymer yarn are aligned and inserted in the weft direction, and the low-melting polymer yarn is melted to reduce the intersection of the warp reinforcing fiber yarn and the weft yarn auxiliary yarn. When bonded with the melting point polymer 10, the woven yarn is not frayed by cutting, and the woven yarn is not misaligned during molding.
[0033]
The volume of reinforcing fibers per square meter of the base material layer constituting the multilayer reinforcing fiber sheet of the present invention is 100 cm from the impregnation and workability of the resin.^ThreeFrom 350cm^ThreeThe range of is preferable. 100cm^ThreeSince the amount of reinforcing fibers per layer is less than the following, the number of substrates to be stacked increases to produce a desired multilayer reinforcing fiber sheet. In other words, since the length of the base material required for producing a multilayer sheet per meter is increased, the processing cost of the base material in the multilayer sheet is increased and the cost is increased, and the number of sheets is increased. Cost is also increased, which is not preferable. 350cm^ThreeSince the amount of fibers per layer will increase when the above is reached, the flow resistance in the resin thickness direction will increase, and the resin impregnation into the multilayer sheet will deteriorate, such being undesirable.
[0034]
In the present invention, the volume of reinforcing fibers per square meter means [volume weight of sheet / reinforcing fiber density].
[0038]
Resin applied to the structure with an impregnating roller even when the resin has a high viscosity when a gap is provided between the yarns of reinforcing fiber yarns in the same layer constituting the multilayer reinforcing fiber sheet of the present invention. Can be moved in the thickness direction of the fiber sheet from the gap between the yarns, and the permeability of the resin to the fiber sheet is improved. Therefore, the dispersion of the resin is improved, and the presence of excess resin between the structure and the fiber sheet can prevent the surface of the cured plate from becoming uneven after the resin is cured. For this reason, the gap between the yarn and the yarn is preferably 0.1 to 2.0 mm.
[0039]
The resin impregnation proceeds from the periphery of the reinforcing fiber yarn constituting the sheet base material to the center portion of the yarn. However, if it is too thick, the distance to the center portion of the yarn is undesirably increased. On the other hand, if the yarn is thin, in order to obtain a sheet base material having a predetermined fiber amount, the yarn interval is reduced, and the permeability of the resin is deteriorated. Therefore, the total fiber cross-sectional area of the reinforcing fiber yarn is 0.2 mm.²~ 2.0mm²The range of is preferable. More preferably 0.3 mm²~ 1.2mm²Range.
[0040]
The reinforcing fiber used in the present invention is a high-strength and high-modulus fiber such as carbon fiber, glass fiber, or polyaramid fiber. Among these, carbon fiber is preferable because it is excellent in alkali resistance. Carbon fiber has a tensile strength of 2,500 to 6,000 MPa and a tensile modulus of 230 to 600 GPa, and is not particularly limited. However, it has a high strength of 4,000 to 6,000 MPa for shear reinforcement of bridge piers and columns. When a carbon fiber having a high elastic modulus of 400 to 700 GPa is used for reinforcement of bending rigidity such as carbon fiber and floor slab, the amount of fiber is small and a predetermined reinforcing effect can be obtained.
[0041]
Further, it is preferable that a large amount of reinforcing fiber yarn sizing agent is attached in terms of improving the processability when producing the multilayer reinforcing fiber sheet. However, if the amount is too large, the impregnation property of the resin is hindered. In particular, in the case of carbon fibers, since the single fiber diameter is as thin as 5 to 10 microns and the resin impregnation property is inferior to other reinforcing fibers, a small amount of adhesion in the range of 0.15 to 0.6% is preferable.
[0042]
In a preferred embodiment of the multilayer reinforcing fiber sheet of the present invention, the reinforcing fiber yarn is a carbon fiber yarn of 10,000 to 30,000 filaments, and the weight per square meter of the sheet substrate is 200 to 350 g. The sheet substrate has two layers, the carbon fiber weight of the fiber sheet is 400 to 700 g per square meter, and the weight of the sheet is 420 to 800 g. The reinforcing fiber is a carbon fiber excellent in alkali resistance, and the yarn of 10,000 to 30,000 filament, that is, the total carbon fiber cross-sectional area of the yarn is 0.3 to 1.2 mm.²Therefore, the impregnation of the resin inside the yarn is good, and the weight per square meter of the sheet base material is 200 to 350 g, so that an appropriate gap can be provided between the yarns. In addition, since the weight of carbon fiber is as high as 420 to 800 g per square meter, the number of laminated sheets becomes 1/2 of the conventional one, and since the weight of the sheet is 420 to 800 g, it depends on the viscosity and thixotropy of the resin. However, the sheet does not slip after being impregnated with the resin before being cured.
[0043]
When the multilayer reinforcing fiber sheet of the present invention is a multi-woven fabric, and the auxiliary yarn when the base material is a woven fabric, the auxiliary yarn does not substantially play a role as a reinforcing fiber and is used for forming a woven fabric structure. Those having a thickness of about 1/3 or less of the thickness of the strip and having a small heat shrinkage rate such as glass fiber, polyaramid fiber, and carbon fiber are preferable.
[0044]
Further, if the yarn density of the auxiliary yarn in the base material is roughened to about 0.5 to 6 yarns / cm, the reinforcing fiber yarns are restrained by the auxiliary yarn and the resin impregnation is good.
[0045]
Using the multilayer reinforcing fiber sheet of the present invention, the structure can be repaired and reinforced as follows.
[0046]
In the case of repairing / reinforcing a concrete structure as a structure, first, dirt on the concrete surface is removed with soapy water, acetone, or the like, and putty is applied to adjust the unevenness to smooth the surface. Next, in order to improve the adhesion with FRP, an epoxy resin primer is applied and allowed to stand for a whole day and night, and then a resin having a room temperature curable resin viscosity of about 2,000 to 25,000 mPa · s is used as an undercoat. Then, after uniformly applying a resin of about 1.5 to 2.5 times the weight of the fiber sheet, a multilayer fiber reinforced sheet is applied, and defoaming is performed simultaneously with the resin impregnation with a grooved resin impregnation roller. Next, after a resin of about 0.5 to 1.5 times the weight of the fiber sheet is uniformly applied as an overcoat on the sheet, a resin-impregnated roller is applied. In the second and subsequent layers, as in the case of the first layer, a predetermined number of sheets may be repeated by applying a resin undercoat, applying a reinforcing sheet, applying a resin-impregnated roller, and applying a topcoat resin.
[0047]
In addition, in the above, a multilayer fiber reinforced sheet may be pasted, and an overcoating resin may be immediately applied thereon, followed by impregnation roller marking.
[0048]
In addition, after the first layer of resin is cured, the next layer may be molded, and the second and third layers may be molded continuously until the first layer of room temperature curable resin is cured. I can do it.
[0049]
The resin used for repair and reinforcement of the present invention may be a room temperature curable resin such as epoxy resin, vinyl ester resin, unsaturated polyester resin, or methyl methacrylate resin.
[0050]
【Example】
(Example 1)
As a reinforcing fiber yarn, 24,000 filament PAN-based carbon fiber (yarn fineness: 14400 denier, specific gravity: 1.80) is used as warp yarn, and glass fiber yarn (ECG 75 1/0 as weft yarn). Fineness: 608 denier, specific gravity: 2.54) and low-melting nylon 50 denier yarn having a melting point of 120 ° C. as a close-up yarn are aligned, and the first and second woven fabric substrates are warp yarns respectively. Density: 1.88 yarns / cm, weft yarn density: 3 yarns / cm, the texture of each woven fabric base material is a plain structure, and the first layer and the second layer are woven with a portion of the first layer of weft yarns. A multilayer fiber reinforced sheet of the present invention in which the low melting point nylon was melted by heating to 150 ° C. with a heater attached on the loom and fused with the warp and the weft was produced. In order to integrate the first layer and the second layer with the woven fabric structure of the first layer weft, first, seven weft yarns are inserted continuously, the first layer is three, the second layer The first layer and the second layer are inserted into a normal plain structure, and the next weft yarn is the first layer of four continuous warp yarns as one unit. The book can be made into a normal plain structure, and next, without crossing with the warp yarn of the first layer, it can be crossed with one warp yarn of the second layer. These can be automatically performed by the operation of a dobby for controlling the opening / closing movement of the warp yarn.
[0051]
The carbon fiber basis weight of the textile substrate of the first layer and the second layer of the multilayer fiber reinforced sheet is 300 g / m²The carbon fiber volume per square meter of the substrate is 167cm^ThreeThe bulk density of the carbon fibers of the sheet was 234%, and the gap between the carbon fiber yarns of the first and second layer woven fabric substrates was 0.3 mm.
[0052]
Next, in order to improve the adhesion to FRP on a smooth concrete surface, an epoxy resin primer is applied and left for a whole day and night. 800g / m²After uniformly coating, the multilayer fiber reinforced sheet was applied as the first layer, and defoaming was performed simultaneously with resin impregnation with a grooved resin impregnated roller. Excess resin has been squeezed out from the lower surface of the sheet. Next, 600 g / m as a top coat on the sheet²After the resin was uniformly applied, the resin impregnated roller was further removed and left as it was to cure the resin. Next, as with the first layer, the second layer of the undercoat resin was 800 g / m.²After uniform coating, a multilayer fiber reinforced sheet is applied, and a resin-impregnated roller is applied to form a top coat of 600 g / m²After uniformly applying the resin, a resin impregnated roller was used to cure the resin. When the second-layer resin-impregnated roller is applied after the undercoat resin is applied, the excess resin has been squeezed out as in the first layer. The surface of the FRP after the resin was cured was smooth, and when the cross section of the FRP was observed, there were no large voids and the resin was sufficiently impregnated.
[0053]
(Comparative Example 1)
The same reinforcing fiber yarns, weft yarns, and eyelet yarns as in the examples were used, the reinforcing fiber yarns were used as warp yarns, the weft glass fiber yarns and the eyelet yarns were aligned, and the warp yarn density: 3.75 / Cm, weft yarn density: A woven fabric having a plain structure of 3 / cm was woven, a low-melting nylon was melted with a heater attached on a loom, and a warp yarn and a weft yarn were bonded to produce a unidirectional carbon fiber fabric.
[0054]
Carbon fiber basis weight of unidirectional carbon fiber fabric is 600g / m²The volume of carbon fiber per square meter of the substrate is 333cm^ThreeThe bulk density of the carbon fibers in the sheet was 204%, and there was almost no gap between the carbon fiber yarns.
[0055]
Next, after the same method as in the example, the same resin amount and the same resin amount were primed on the concrete surface, the above-mentioned carbon fiber fabric was pasted, and defoaming was performed simultaneously with resin impregnation with a grooved resin impregnation roller. Excess resin was not squeezed out from the lower surface of the sheet in both layers. The surface of the FRP after the resin was cured was in an unpleasant state, with excess resin accumulating on the concrete surface and uneven. Further, when the cross section of FRP was observed, there were large voids, and there were portions where the resin was not sufficiently impregnated.
[Brief description of the drawings]
FIG. 1 is a partially broken perspective view showing a concept of a multilayer reinforcing fiber sheet according to the present invention.
FIG. 2 is a perspective view of a unidirectional fabric as a base material constituting the multilayer reinforcing fiber sheet according to the present invention.
FIG. 3 is a perspective view of a unidirectional non-crimp fabric as a base material constituting the multilayer reinforcing fiber sheet according to the present invention.
FIG. 4 is a perspective view of a tow sheet as a base material constituting the multilayer reinforcing fiber sheet according to the present invention.
FIG. 5 is a partially broken perspective view showing a multilayer reinforcing fiber sheet according to the present invention.
FIG. 6 is a cutaway view of a unidirectional double woven fabric as a multilayer reinforcing fiber sheet according to the present invention.
[Explanation of symbols]
1: Multilayer reinforcing fiber sheet
2: Reinforced fiber yarn
2₁: Reinforcing fiber yarn in the first layer
2₂: Second-layer reinforcing fiber yarn
3: Substrate
3₁: Base material of the first layer
3₂: Base material of the second layer
4: Weft thread (auxiliary thread)
4₁: First layer weft
4₂: Weft of the second layer
5: Warp auxiliary thread
6: Support
7: Mesh wire rod
8: Mesh wire
9: Adhesive
10: Low melting point polymer
B: Multi-layer reinforcing fiber sheet length direction
B: Base material length direction
A: Air gap

Claims (10)

The base material in which the reinforcing fiber yarns are arranged in parallel to the length direction of the sheet is multilayered so that the directions of the reinforcing fibers are the same, and adjacent layers are integrated with each other , and the bulk density of the reinforcing fibers ( A multilayer reinforcing fiber sheet, wherein the volume of the sheet / the volume of reinforcing fibers is 220 to 300% . The multilayer reinforcing fiber sheet according to claim 1, wherein the volume of reinforcing fibers per square meter of the substrate is 100 to 350 cm ³ . The multilayer reinforcing fiber sheet according to claim 1 or 2 , wherein the base material is a unidirectional woven fabric, and the integration means is a woven structure. The multilayer reinforcing fiber sheet according to claim 1 or 2 , wherein the integration means is adhesion. The multilayer reinforcing fiber sheet according to claim 4 , wherein a mesh-like material is interposed between layers of the base material. The multilayer reinforcing fiber sheet according to claim 4 or 5 , wherein the substrate is a woven fabric. The reinforcing fiber yarn is a carbon fiber yarn of 10,000 to 30,000 filaments, wherein the base material has a weight of 200 to 350 g per square meter, and the base material has two layers. Item 7. The multilayer reinforcing fiber sheet according to any one of Items 1 to 6 . Multilayer reinforcing fiber sheet according to any one of claims 1 to 7 comprising a gap is provided between the reinforcing fiber yarns. A method for repairing or reinforcing a structure, comprising applying a resin to a portion of the structure to be repaired or reinforced and affixing and reinforcing the multilayer reinforcing fiber sheet according to any one of claims 1 to 8. . The method for repairing or reinforcing a structure according to claim 9 , wherein the structure is a concrete structure.

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