JP2000085044A - Multilayer reinforcing fiber sheet and method for repairing/reinforcing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the quantity of reinforcing fibers per one sheet and to improve resin-impregnation properties by laying sheet base material layers in which reinforcing fiber threads are arranged in parallel in the sheet length direction to overlap each other so that the reinforcing fiber direction is the same and integrating the adjoining layers. SOLUTION: For example, in a multilayer reinforcing fiber sheet 1, two layers of the base material 31 of the first layer in which numbers of fiber reinforced thread stripes 2 are arranged in parallel in the sheet length direction and the base material 32 of the second layer are laid to overlap each other so that the reinforcing fiber direction is the same. The base material 31 and the base material 32 are integrated with each other by an integration means such as weaving organization and adhesion. In this process, the volume of the reinforcing fibers per one square meter of one layer of the base material constituting the sheet 1 is made 100-350 cm3 from the impregnation properties and workability of a resin. Moreover, when the bulk density of the sheet 1 (the volume of the sheet/the volume of the reinforcing fibers) is made 220-300%, resin-impregnation properties can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for repairing and reinforcing a reinforcing fiber sheet and a structure.

[0002]

2. Description of the Related Art Concrete structures such as bridge decks, bridge piers, tunnels, chimneys and buildings deteriorate due to neutralization of concrete and rust due to long-term use, and load reduction due to relaxation of restrictions on the weight of passing vehicles. Due to the review of seismic standards, which assume increased damage, earthquake damage and larger earthquakes,
Repairs and reinforcements are needed.

[0003] Recently, a method of attaching a sheet made of reinforcing fibers to the structure and impregnating it with a room-temperature-curable resin, that is, a so-called hand lay-up method, has attracted attention because repair and reinforcement of these structures are easy to perform. ing. In this method, the resin is completely cured at room temperature in about one week, a reinforced plastic plate is formed on site, and a reinforced plastic (hereinafter, FR)
Since the plate and the structure are simultaneously bonded, repair and reinforcement work is simplified.

[0004] However, the repair / reinforcement portion of the structure includes a vertical surface such as a ceiling surface such as a floor slab lower surface, a pier, and a pillar of a building structure. As a result, the viscosity of a commonly used resin is as high as 2,000 to 25,000 mPa · s (millipascal × sec). Usually, the hand lay-up molding method is frequently used as a molding method for boats and tanks, but the viscosity of the room temperature-curable unsaturated polyester resin or vinyl ester resin used in the sheet is reinforced to form a sheet. 200-500m from the viewpoint of resin impregnation of fiber
Pa · s, at most about 1,000 mPa · s. On the other hand, the viscosity of the resin used for repair / reinforcement of the structure is extremely high, and the resin impregnation into the reinforcing fibers is not so good.

[0005] For this reason, the reinforcing fiber sheet that is frequently used for repairing and reinforcing structures is thin, the reinforcing fiber is made of carbon fiber, and the carbon fiber weight is 200 to 300 g / weight.
m ² , that is, a thin reinforcing fiber sheet in which carbon fibers are arranged in one direction in a volume of about 110 to 170 cm ³ per square meter.

Accordingly, in order to cope with the amount of reinforcing fibers required for repairing and reinforcing a structure, the number of reinforcing fiber sheets to be used increases, and a resin impregnation operation is required for each sheet. Is more and more troublesome.

On the other hand, if the amount of reinforcing fibers per sheet is simply increased, the reinforcing fiber yarns constituting the sheet are densely arranged, the degree of convergence is increased, and the fiber spacing is clogged, making resin impregnation difficult. .

[0008]

SUMMARY OF THE INVENTION In view of the above situation, the present invention provides a multilayer reinforced fiber sheet having a large amount of reinforcing fiber per sheet and excellent in resin impregnating property, and also has an improved workability. An object of the present invention is to provide a method for repairing and reinforcing an excellent structure.

[0009]

In order to achieve the above object, the present invention basically has the following arrangement. That is,
"A sheet base material in which reinforcing fiber yarns are arranged in parallel in the length direction of the sheet, the multilayers are overlapped so that the direction of the reinforcing fibers is the same, and the adjacent layers are integrated with each other. Reinforced fiber sheet. "

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a partially cutaway perspective view showing the concept of a multilayer reinforced fiber sheet 1 according to the present invention. The first in which many reinforcing fiber yarns 2 are arranged in parallel in the length direction of the sheet.
2 of the layers th substrate 3 ₁ and the second layer of the base material 3 ₂ overlaps so that the direction of the reinforcing fibers is the same, the substrate 3 ₁ and the base 3 ₂ weave or bonding or the like (Not shown in FIG. 1). Note that the number of layers is not necessarily two, but may be three or four, and is not limited.

[0011] The multilayer reinforced fiber sheet of the present invention can be classified according to the form of the substrate and the means of integration for forming a multilayer structure.

First, the case where the integrating means is by adhesion will be described. FIGS. 2 to 4 show the forms of the base material constituting the multilayer reinforced fiber sheet of the present invention.

FIG. 2 shows that the reinforcing fiber yarns 2 are arranged in the longitudinal direction of the base material, that is, the warp direction of the fabric, and the auxiliary yarns 4 thinner than the reinforcing fiber yarns are arranged in the weft direction. 4
Is a unidirectional woven fabric interwoven and woven. FIG. 3 shows that the reinforcing fiber yarn 2 and the auxiliary yarn 5 are oriented in the longitudinal direction of the base material, that is, the warp direction of the woven fabric, the auxiliary yarn 4 is oriented in the weft direction, and the auxiliary yarn 4 of the weft yarn assists the warp yarn. This is a so-called one-way non-crimp fabric in which the reinforcing fiber yarns 2 are straightly oriented without being interlaced with the wefts 4 and intersected with the yarns 5. FIG. 4 shows a sheet of reinforcing fiber yarn 2 in which reinforcing fiber yarns are arranged straight and parallel in one direction and a mesh-shaped support 6 on the surface of an adhesive or mesh wire 7, 8. It is a toe sheet that has been fused and integrated with a polymer. The mesh-shaped support 6 is not necessarily limited to two directions of wires orthogonal to each other.
The direction may be three directions oriented at ± α ° with respect to the length direction and the reinforcing fiber yarn. Further, the base material may be a unidirectional knitted fabric in which reinforcing fiber yarns arranged in one direction are knitted with a thin auxiliary yarn.

Substrates having these forms have been used so far for repairing and reinforcing structures, and are not particularly new.

The multilayer reinforced fiber sheet of the present invention is obtained by laminating a large number of these substrates and integrating them. FIG.
FIG. 1 is a partially broken perspective view of an embodiment of the multilayer reinforced fiber sheet of the present invention. Bonded by adhesive means, a multilayer reinforcing fiber sheet obtained by superposing two sheets of unidirectional woven fabric as the substrate, the first layer of the base material 3 ₁ and the second layer of the base material 3 ₂ interlayer is punctiform It is adhered with agent 9.

[0016] To adhere the point-like, hot-melt thermoplastic resin powder base 3 ₁ of uniformly sparsely sprinkled on one side,
The adhesive can be adhered to a surface to the base material 3 ₂ Again thermoplastic resin heated and melted to the substrate 3 ₁ and the base 3 ₂ deposition.

Further, the state of adhesion of the adhesive may be linear. In order to adhere linearly, when weaving the woven fabric, the polymer yarn and the weft made of a thermoplastic resin having heat melting property were aligned and woven into the woven fabric, and the warp and the weft were bonded by melting the polymer yarn. , A so-called eyelet fabric is produced. The fabric lap, can again be heated above the melting of the polymer threads to melt the polymer to adhere the substrate 3 ₁ and the base 3 ₂ by pressing as necessary. Further, the polymer threads is a number the interposed substrate between the substrate 3 ₁ and the base 3 _2, also obtained by monkey is heated to above the melting of the polymer threads melt the polymer. Also, room temperature tacky mesh-like material which the adhesive has been applied with the base material 3 ₁ and the substrate 3 is interposed between the _two can be adhered.

As described above, it is preferable that the adhesive is adhered to the substrate in the form of dots or lines because the adhesive does not hinder resin impregnation. The impregnating roller is preferable because misalignment of the reinforcing fiber yarn and the weft yarn can be prevented. Also,
The bonding between the substrates may be performed by interposing a thin film of about 5 to 15 g / m ^{2 made of a} thermosetting resin in a B stripe state between the layers of the substrates. Or spraying the atomized thermoplastic resin or thermosetting resin solution dissolved in a diluent to the substrate 3 _1, the substrate 3 by drying the diluent ₂
Can also be glued.

The impregnating property of the resin is closely related to the sheet air permeability according to the JIS L 1096 method.
It was found that it was preferable to be ~ 300 CC / cm ² / sec.

When the ventilation rate is less than 40 CC / cm ² / sec,
The bulk density of the carbon fibers forming the reinforcing fiber yarn is reduced, that is, the space formed between the carbon fibers is small,
Further, the gap between the reinforcing fiber yarns is small, the impregnation property of the resin is poor, and voids are generated.

Further, at 300 CC / cm ² / sec, since the woven fabric has a large gap between the reinforcing fiber yarns, the thickness of the reinforcing fiber portion increases, the surface becomes uneven, and the reinforcing fiber yarns are firmly bundled. Therefore, there is a problem that the impregnating property of the resin into the reinforcing fiber yarn is reduced.

The measurement of the air permeability was in accordance with the air permeability A method of JIS L 1096 method 6.27.

That is, a 20 cm × 20 cm sheet test piece was attached to a 38.3 cm ² vent hole at one end of a cylinder by a predetermined method, and a tilt type barometer was attached to a water column 1.2 by a rheostat.
The suction fan was adjusted to indicate a pressure of 7 cm, and the amount of air passing through the sheet test piece (CC) was calculated from the pressure indicated by the vertical barometer at that time and the type of air hole used, according to a conversion table attached to the tester. / Cm ² / sec) was determined and the average value of the five measurement results was taken as the ventilation rate.

The sample was left standing in a room at a temperature of 20 ° C. and a humidity of 65% for 24 hours, and then measured in that atmosphere. In the examples described below, as a ventilation meter,
Fragile type testing machine AP- of Daiei Kagaku Seiki Seisakusho Co., Ltd.
360 was used.

The thermoplastic resin used for bonding the substrates according to the present invention includes nylon, copolymerized nylon, polyester, copolymerized polyester, vinylidene chloride, vinyl chloride, polyeletan, polyethylene, polypropylene, polyvinyl alcohol, acrylic and the like. Of these, copolymer nylon which melts at a low melting point of about 70 to 160 [deg.] C. is preferred because the heating and crimping operations for integration are easy and the adhesiveness is good.

The thermosetting resin used for bonding the substrates according to the present invention is an epoxy resin, a vinyl ester resin, an unsaturated polyester resin, a phenol resin or the like. Preferably, the multilayer reinforced fiber sheet according to the present invention is used. When the same impregnating resin used for the reinforcing and reinforcing method used, that is, when the impregnating resin is an epoxy resin, the thermosetting resin used for bonding is preferably an epoxy resin. Adhesives that are tacky at room temperature include styrene / butadiene rubber, polyisobutylene, ethylene / vinyl acetate copolymer, acrylic, and vinyl acetate copolymer.

The adhesive used for bonding the substrates of the present invention does not need to be essentially a resin for impregnating the reinforcing fiber resin.
Also, the degree of adhesion between the substrates does not need to be strong,
The amount of the adhesive used for bonding the base materials should be as small as possible, as long as the bonding between the base materials does not peel off during handling, and is preferably about ² to 15 g / m ² .
When the amount is 15 g / m ² or more, impregnation of the resin into the multi-reinforced fiber sheet is impaired, or the adhesion between the impregnating resin and the adhesive is unfavorably deteriorated.

The embodiment of the multilayer reinforced fiber sheet of the present invention shown in FIG. 5 shows an example of a unidirectional woven fabric as a base material.
The one-way non-crimp fabric shown in FIG.
It may be a sheet or a combination thereof.

Further, the multilayer reinforced fiber sheet of the present invention preferably has an appropriate gap between the base materials of adjacent layers. At the time of the above-mentioned integration by adhesion, a mesh-like material may be interposed between the base materials. When a mesh-like material is present between the substrate 3 ₁ and the base 3 _2, uncured transmitted through the substrate 3 ₁ (or 3 ₂₎ in the roller engaging the resin-impregnated resin, the mesh-like material with a thickness Since the resin enters the voids, that is, has an uncured resin layer between the layers, the resin impregnates the base material 3 ₂ (or 3 ₁ ), and the resin impregnation becomes easy even if the fiber sheet is thick. In the mesh-like material, the wires are oriented in two or three directions, and the preferable thickness is 0.1 to 0.4 mm. If the thickness is too large, a large amount of resin is present between the base materials, that is, the amount of the resin used increases, so that the cost is increased and the cost is uneconomical.

Further, the multilayer reinforced fiber sheet of the present invention is a so-called unidirectional multi-layer woven fabric in which reinforcing fiber yarns are superposed in multiple layers and are integrated in a weave structure by interlacing of auxiliary yarns orthogonal to the reinforcing fiber yarns. You may. FIG. 6 is a cross-sectional view showing a double woven fabric as one embodiment of the unidirectional multiple woven fabric. In the drawings, it comprises a reinforcing fiber yarns 2 ₁ plain weave fabric 3 ₁ consisting of the auxiliary thread 4 ₁ Tokyo, a plain weave fabric 3 ₂ multilayer structure consisting of reinforcing fiber yarns 2 ₂ and the auxiliary thread 4 _2. And the plain weave fabric 3 ₁ and plain woven 3 ₂ by a part of the auxiliary yarn plain weave 3 ₁ 4 ₁ and the flat reinforcing fiber yarns 2 ₂ of the fabric 3 ₂ intermingled with one another are held together.

When the woven fabric is integrated as described above, an adhesive or the like does not need to be used for the integration, so that the impregnation of the resin is not hindered. In addition, plain fabric 3 ₁
And because it forms a gap A portion between the plain weave fabric 3 _2, high-viscosity resin from the lower surface of the flat fabric 3 ₁ by impregnation roller cliff is performed resin impregnation into plain weave 3 _1. Also, usually, so that the resin is spread throughout the entire surface of the sheet, since the required amount or more amount of resin is applied, the air present between excess resin and concrete and fabric 3 ₁ and the fabric 3 ₁ inside the resin The displaced air moves to the space A. Fabric 3 ₁ never as embrace the air between the concrete and the resin impregnated into the fabric 3 ₁ is performed. Next, the resin is accumulated in gaps A unit is impregnated from the bottom surface of the plain weave 3 ₂ inside the fabric 3 _2, also impregnated into the inside of the fabric 3 ₂ by resin applied to the upper surface of the plain weave 3 ₂ Therefore, the impregnating property is not impaired by increasing the weight of the reinforcing fibers.

When weaving a multi-layer fabric, 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 form a warp reinforcing fiber yarn and a weft auxiliary yarn. When the intersection is bonded with the low melting point polymer 10, the woven yarn is not frayed by cutting, and at the time of molding,
There is no misalignment of the yarn.

The volume of the reinforcing fibers per square meter of one layer of the base material constituting the multilayer reinforcing fiber sheet of the present invention is from 100 cm ³ to 350 c from the resin impregnation and workability.
A range of m ³ is preferred. If it is 100 cm ³ or less, the amount of reinforcing fibers per layer will be small, so that the number of base materials to be laminated will be large in order to produce a desired multilayer reinforcing fiber sheet. In other words, the length of the base material required to produce a multi-layer sheet per meter increases, so that the processing cost of the base material in the multi-layer sheet increases, the cost increases, and the number of sheets increases. The cost also increases, which is not desirable. On the other hand, if it is 350 cm ³ or more, the amount of fibers per layer becomes large, so that the flow resistance in the thickness direction of the resin becomes large, and the resin impregnating property of the multilayer sheet becomes unfavorable.

The volume of the reinforcing fiber per square meter in the present invention means [weight of sheet / weight of reinforcing fiber].

The bulk density of the multilayer reinforced fiber sheet of the present invention is preferably 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 becomes large, that is, the gap between the single fibers becomes small, so that the resin impregnating property is deteriorated. It is difficult to prevent air from being trapped during the impregnation. When the bulk density is 300% or more, there is no problem of resin impregnation and air entrapment. However, since the fibers of the sheet are bulky, the amount of resin necessary to fill the space between the fibers of the sheet is increased. Will increase. In addition, it is possible to hold a bulky sheet and reduce the amount of resin by applying a resin and applying an impregnating roller, but the pressed sheet recovers to its original bulky state, that is, a springback phenomenon. Occurs, the amount of the resin with respect to the recovered sheet is insufficient, and the FRP in which the resin is cured is in a state where many voids are contained.

The bulk density V in the present invention is a value calculated by the following formula.

V = A × t ÷ (w / ρ) × 100 (%) where, t: thickness of multilayer reinforcing fiber sheet (cm) A: area of fabric (cm ² ) w: area of fabric A Weight of reinforcing fiber sheet (g) ρ: Density of reinforcing fiber (g / cm ³ ) The method of measuring the thickness of the sheet is based on JIS R 760.
2 The thickness measuring instrument described in Section 5.6 complies with the dial gauge method. However, the load was set to 50 kPa, the value 20 seconds after the load was applied to the sheet was read, and the value was 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 positions of the auxiliary yarns to be overlapped are shifted from each other so that the effect of the weft auxiliary yarn on the sheet thickness is minimized. Then, the thickness per sheet was determined by dividing by the number of sheets to be superposed.

When a gap is provided between the reinforcing fiber yarns in the same layer constituting the multilayer reinforcing fiber sheet of the present invention,
Even if the resin has high viscosity, the resin applied to the structure can be moved in the thickness direction of the fiber sheet from the gap between the yarns by the impregnation roller, and the permeability of the resin to the fiber sheet is improved. . Therefore, the dispersion of the resin is improved, and the presence of the extra resin between the structure and the fiber sheet can prevent the surface of the cured plate from being uneven after the resin is cured. From such a thing,
It is preferable that the gap between the yarns is 0.1 to 2.0 mm.

The resin impregnation proceeds from the periphery of the reinforcing fiber yarn constituting the sheet base material to the center of the yarn. However, if the resin is too thick, the distance to the center of the yarn becomes longer, which is preferable. Absent. Further, when the yarn is thin, in order to obtain a sheet base material having a predetermined fiber amount, the yarn interval is reduced, and the resin permeability is deteriorated. Accordingly, the sum of the fiber cross-sectional areas of the reinforcing fiber yarns is 0.2 mm ^{2 to} 2.0 mm ²
Is preferable. More preferably, 0.3 mm < ² > -1.
The range is 2 mm ² .

The reinforcing fibers used in the present invention are carbon fibers,
High strength and high modulus fiber such as glass fiber and polyaramid fiber. Among them, carbon fibers are preferable because of their excellent alkali resistance. The tensile strength of carbon fiber is 2,50
0-6,000MPa, tensile modulus 230-600G
The range of Pa is not particularly limited, but high-strength carbon fibers of 4,000 to 6,000 MPa for shear reinforcement of bridge piers and columns, and 400 to 700 for bending rigidity reinforcement of floor slabs and the like.
When a carbon fiber having a high elastic modulus of GPa is used, a predetermined reinforcing effect can be obtained with a small amount of fiber.

Further, it is preferable that a large amount of the sizing agent for the reinforcing fiber yarns be adhered in order to improve the processability in the production of the multilayer reinforcing fiber sheet, but if it is too large, the impregnating property of the resin is impaired. In particular, in the case of carbon fibers, the single fiber diameter is as thin as 5 to 10 microns, and the resin impregnation property is inferior to other reinforcing fibers. Therefore, a small amount of 0.15 to 0.6% is preferable.

In a preferred embodiment of the multilayer reinforcing fiber sheet of the present invention, the reinforcing fiber yarn is 10,000 to 30,
2,000 filaments of carbon fiber yarn, and the weight per square meter of the sheet substrate is 200 to 350 g.
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 having excellent alkali resistance, and 10,000 to 30,000.
Since the sum of the carbon fiber cross-sectional areas of the 0 filaments, that is, the filaments, is 0.3 to 1.2 mm ² , the resin can be impregnated inside the yarns, and the weight per square meter of the sheet base material can be reduced. Since the weight is 200 to 350 g, an appropriate gap can be provided between the yarns. Further, since the weight of the carbon fiber is as large as 420 to 800 g per 1 m 2, the number of laminations is 従 来 of that of the related art.
Since it is 20 to 800 g, depending on the viscosity and thixotropy of the resin, the sheet does not slip before being cured after being impregnated with the resin.

When the multi-layered reinforced fiber sheet of the present invention is a multi-woven fabric and when the base material is a woven fabric, the auxiliary yarn does not substantially serve as a reinforcing fiber and is used for forming a fabric structure. It is preferable that the thickness of the reinforcing fiber yarn is about 1/3 or less, and that the heat shrinkage of glass fiber, polyaramid fiber, carbon fiber or the like is small.

The yarn density of the auxiliary yarn in the substrate is
When the coarseness is set to about 0.5 to 6 yarns / cm, the reinforcing fiber yarn is restrained loosely by the auxiliary yarn, and the resin impregnation is good.

Using the multilayer reinforced fiber sheet of the present invention, a structure can be repaired and reinforced in the following manner.

A description will be given of a case where a concrete structure is repaired and reinforced as a structure. First, dirt on a concrete surface is removed with soap water or acetone, and putty is applied to adjust the unevenness to smooth the surface. I do. Then, in order to improve the adhesion with FRP, after applying an epoxy resin-based primer and leaving it for 24 hours a day, an undercoat of a room temperature curing type resin having a resin viscosity of about 2,000 to 25,000 mPa · s is applied thereon. After uniformly applying a resin 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 resin impregnation with a grooved resin impregnation roller. Then, after uniformly applying a resin about 0.5 to 1.5 times the weight of the fiber sheet as an overcoat on the sheet,
Further, a resin impregnated roller is applied. The second and subsequent layers are 1
As in the case of the layer, a predetermined number of sheets may be repeated by performing undercoating of the resin, attaching a reinforcing sheet, applying a resin impregnated roller, and applying an overcoating resin.

In the above, a multilayer fiber reinforced sheet may be stuck, a top coat resin may be immediately applied thereon, and then an impregnating roller may be applied.

After the first layer of resin is cured, the next layer may be molded, or the second and third layers may be continuously formed until the first layer of the room-temperature-curable resin is cured. Can be molded.

The resin used for the repair / reinforcement of the present invention may be a cold-setting resin such as an epoxy resin, a vinyl ester resin or an unsaturated polyester resin, or a methyl methacrylate resin.

[0050]

EXAMPLES (Example 1) 24,000 reinforced fiber yarns
Filament PAN-based carbon fiber (filament fineness: 144
00 denier, specific gravity: 1.80) as the warp yarn,
Glass fiber yarns as weft yarns (ECG 75
1/0, fineness: 608 denier, specific gravity: 2.54) and low melting point nylon 50 having a melting point of 120 ° C. as staple yarn.
The denier yarns are aligned, and the first and second woven fabric bases each have a warp density of 1.88 yarns / cm, a weft yarn density of 3 yarns / cm, and each woven base material has a flat structure. Then, the first layer and the second layer are united in a woven structure with a part of the first layer weft, heated to 150 ° C. by a heater mounted on a loom to melt the low melting point nylon, and A multilayer fiber reinforced sheet of the present invention to which weft yarn was adhered was produced. In addition, the first layer and the second layer are integrated by a woven fabric structure of the first layer of weft yarn. First, seven weft yarns are continuously inserted, and three first weft yarns and three second weft yarns are used. Into the first layer and the second layer
The next weft yarn has a normal flat design, and the next weft yarn has a normal flat design with four of the four continuous warp yarns as one unit. It can be performed by crossing with one warp yarn of the second layer without crossing with the warp yarn of the layer. These can be automatically performed by operating a dobby that controls the opening / closing motion of the warp yarn.

The first and second layers of the multi-layer fiber reinforced sheet have a basis weight of 300 g / m ² of carbon fiber and a carbon fiber volume of 167 cm per square meter of the substrate.
^3. The bulk density of the carbon fibers in the sheet is 234%, and the gap between the carbon fiber yarns of the first and second layers of the woven fabric substrate is 0.1%.
3 mm.

Next, in order to improve the adhesion to the FRP on the smooth concrete surface, an epoxy resin-based primer was applied and allowed to stand for a whole day and night, and then a room temperature curing type resin having a resin viscosity of 10,000 mPa · s was used. 800g as undercoat
/ M ² , the multilayer fiber reinforced sheet was applied as a first layer, and defoaming was performed simultaneously with resin impregnation using a grooved resin impregnation roller. Excess resin has been squeezed out from the lower surface of the sheet. Next, after a resin of 600 g / m ² was uniformly applied as a top coat on the sheet, a resin impregnating roller was further applied, and the resin was left as it was to cure the resin. Next, the undercoat resin of the second layer is applied in the same manner as the first layer.
After uniformly applying 0 g / m ² , a multi-layer fiber reinforced sheet was applied, and a resin-impregnated roller was applied.
/ M ² of resin was uniformly applied, and then the resin was further cured by a resin impregnated roller. When the second layer of the resin-impregnated roller was applied after applying the undercoat resin, excess resin was squeezed out in the same manner as in the first layer. FRP after resin is cured
The surface of the sample was smooth, and when the cross section of the FRP was observed, no large voids were found and the resin was sufficiently impregnated.

(Comparative Example 1) The same reinforcing fiber yarn, weft yarn, and staple yarn as in the example were used, the reinforced fiber yarn was used as a warp yarn, and the weft yarn glass fiber yarn and the staple yarn were aligned. , Warp yarn density; 3.75 yarns / cm, weft yarn density;
A woven fabric having a flat structure of 3 yarns / cm was woven, a low-melting-point nylon was melted by a heater mounted on a loom, and a one-way carbon fiber woven fabric in which a warp and a weft were bonded was produced.

The carbon fiber basis weight of the unidirectional carbon fiber fabric is 60
0 g / m ² , the carbon fiber volume per square meter of the substrate is 333 cm ³ , and the bulk density of the carbon fibers in the sheet is 204
%, There was almost no gap between the carbon fiber yarns.

Next, the same method and the same resin as in the example were used to undercoat the concrete surface with the same amount of resin. Then, the above-mentioned carbon fiber woven fabric was applied, and defoaming was performed simultaneously with resin impregnation with a grooved resin impregnation roller. However, no excess resin was squeezed out from the lower surface of the sheet in both the first and second layers. After the resin was cured, the surface of the FRP was uneven, with excess resin remaining on the concrete surface, and the appearance was poor. Also, FR
Observation of the cross section of P revealed that there were large voids, and that some portions were not sufficiently impregnated with the resin.

[Brief description of the drawings]

FIG. 1 is a partially broken perspective view showing the concept of a multilayer reinforced fiber sheet according to the present invention.

FIG. 2 is a perspective view of a unidirectional woven fabric as a base material constituting the multilayer reinforced fiber sheet according to the present invention.

FIG. 3 is a perspective view of a unidirectional non-crimp fabric as a base material of the multilayer reinforced fiber sheet according to the present invention.

FIG. 4 is a perspective view of a tow sheet as a base material constituting the multilayer reinforced fiber sheet according to the present invention.

FIG. 5 is a partially broken perspective view showing a multilayer reinforced fiber sheet according to the present invention.

FIG. 6 is a cutaway view of a unidirectional double woven fabric as a multilayer reinforced fiber sheet according to the present invention.

[Explanation of symbols]

1: multilayer reinforcing fiber sheet 2: reinforcing fiber yarns 2 _1: strengthening of the first layer fiber yarns 2 _2: second layer of reinforcing fiber yarns 3: substrate 3 _1: the first layer of the base material 3 _2: second layer of the base material 4: weft (auxiliary yarn) 4 _1: first-layer weft 4 _2: second layer of weft 5: vertical auxiliary yarn 6: support 7: mesh wire rod 8: mesh wire 9: adhesive 10: low melting point polymer a: multilayer reinforced fiber sheet length direction b: base material length direction A: void

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 4F100 AD11A AD11B AG00 AK48 AT00C BA02 BA03 BA06 BA08 BA13 BA23 DC16C DG01A DG01B DG12 EC18 GB90 JA13A JA13B JL05 YY00A YY00B 4L048 AA03 AA05 AA24 CA09

Claims (11)

[Claims] (1) A substrate in which reinforcing fiber yarns are arranged in parallel with the length direction of a sheet, wherein a plurality of base layers are overlapped so that the direction of reinforcing fibers is the same, and adjacent layers are integrated with each other. And a multilayer reinforced fiber sheet. 2. The multilayer reinforcing fiber sheet according to claim 1, wherein the volume of the reinforcing fibers per square meter of the base material is 100 to 350 cm ³ . 3. The multilayer reinforced fiber sheet according to claim 1, wherein the bulk density of the reinforcing fibers (volume of sheet / volume of reinforcing fibers) is 220 to 300%. 4. The multilayer reinforced fiber sheet according to claim 1, wherein said base material is a unidirectional woven fabric, and said integrating means is a woven structure. 5. The multi-layer reinforced fiber sheet according to claim 1, wherein said unifying means is formed by bonding. 6. The multilayer reinforced fiber sheet according to claim 5, wherein a mesh-like material is interposed between the layers of the base material. 7. The multilayer reinforced fiber sheet according to claim 5, wherein the substrate is a woven fabric. 8. The method according to claim 8, wherein the reinforcing fiber yarn is 10,000 to 30,
9. The multilayer according to any one of claims 1 to 8, wherein the base material is a carbon fiber yarn of 000 filaments, the base material has a weight per square meter of 200 to 350 g, and the base material has two layers. Reinforced fiber sheet. 9. The multilayer reinforcing fiber sheet according to claim 1, wherein a gap is provided between the reinforcing fiber yarns. 10. A structure characterized in that a resin is applied to a portion of the structure to be repaired or reinforced, and the multilayer reinforced fiber sheet according to any one of claims 1 to 9 is attached and repaired / reinforced. Repair or reinforcement method. 11. The method for repairing or reinforcing a structure according to claim 10, wherein said structure is a concrete structure.