BOND CONSTRUCTION AND BONDING METHOD OF FRP MATERIAL TO STRUCTURE

Abstract

Provided are: a bond construction of an FRP material to a structure characterized in that a bonding layer formed from a fibrous substrate and a resin is interposed between the structure and the FRP material, and the bonding layer is protruded from an edge of the FRP material; and a bonding method. Repair or reinforcement of an existing structure can be made easily and reliably at a construction site with a required FRP material, and in particular, a sufficiently strong bonding force can be exerted between the structure and the FRP material for repair or reinforcement and a targeted repair or reinforcement performance due to the FRP material can be exhibited for the structure more reliably.

Claims

1. A bond construction of an FRP material to a structure characterized in that a bonding layer formed from a fibrous substrate and a resin is interposed between the structure and the FRP material, and the bonding layer is protruded from an edge of the FRP material.

2. The bond construction of an FRP material to a structure according to claim 1, wherein a protrusion length of the bonding layer from the edge of the FRP material is 5 mm or more and 50 mm or less.

3. The bond construction of an FRP material to a structure according to claim 1, wherein a surface of the structure onto which the bonding layer is installed comprises a steel.

4. The bond construction of an FRP material to a structure according to claim 1, wherein a surface of the structure onto which the bonding layer is installed comprises an FRP.

5. The bond construction of an FRP material to a structure according to claim 1, wherein the fibrous substrate used in the bonding layer is made in a form of at least one of a mat-like form in which continuous fibers are randomly oriented, a mesh sheet-like form having pores, and a mat-like form composed of short cut fibers.

6. The bond construction of an FRP material to a structure according to claim 1, wherein a fiber volume content of the bonding layer is in a range of 10% to 40%.

7. The bond construction of an FRP material to a structure according to claim 1, wherein a sectional area of pores per unit width of a single sheet of the fibrous substrate used in the bonding layer is in a range of 0.05 mm.sup.2/mm to 1.0 mm.sup.2/mm.

8. The bond construction of an FRP material to a structure according to claim 1, wherein the resin of the bonding layer is the same as a matrix resin of the FRP material.

9. The bond construction of an FRP material to a structure according to claim 1, wherein a fibrous substrate for intermediate suction extending in an installation section of the FRP material and protruding from an edge of the FRP material is provided, and the fibrous substrate for intermediate suction is overlapped onto the fibrous substrate forming the bonding layer at a position protruding from the edge of the FRP material.

10. A bonding method of an FRP material to a structure comprising: a step of surface treating a bonding surface of the structure; a step of disposing a fibrous substrate forming a bonding layer and a reinforcing fiber substrate forming the FRP material in this order on the bonding surface of the structure so that the fibrous substrate is protruded from an edge of the reinforcing fiber substrate, and temporarily fixing both substrates; a step of sealing the fibrous substrate and the reinforcing fiber substrate, and decompressing a sealed interior; a step of injecting a resin into the decompressed sealed interior; and a step of hardening and curing the injected resin.

11. The bonding method of an FRP material to a structure according to claim 10, wherein the bonding surface of the structure comprises a steel.

12. The bonding method of an FRP material to a structure according to claim 10, wherein the bonding surface of the structure comprises an FRP.

13. The bonding method of an FRP material to a structure according to claim 10, wherein the same resin as the injected resin is applied to the bonding surface of the structure before disposing the fibrous substrate.

14. The bonding method of an FRP material to a structure according to claim 10, wherein the resin is injected simultaneously with respect to the fibrous substrate and the reinforcing fiber substrate.

15. The bonding method of an FRP material to a structure according to claim 10, wherein in the disposing step of the reinforcing fiber substrate, a fibrous substrate for intermediate suction is disposed so as to extend in an installation section of the reinforcing fiber substrate, protrude from an edge of the reinforcing fiber substrate and overlap onto the fibrous substrate at a protruding position.

16. The bonding method of an FRP material to a structure according to claim 10, further comprising a step of disposing a release substrate, which covers the whole of the fibrous substrate and the reinforcing fiber substrate and which can be peeled off after hardening the injected resin, between the temporarily fixing step and the sealing and decompressing step.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0031] FIG. 1 is a schematic diagram showing the bond construction and bonding method of an FRP material to a structure according to an embodiment of the present invention.

[0032] FIG. 2 is a schematic diagram showing the bond construction and bonding method of an FRP material to a structure according to another embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0033] Hereinafter, embodiments of the present invention will be explained referring to figures.

[0034] FIG. 1 shows a bond construction and a bonding method of an FRP material to a structure according to an embodiment of the present invention, and in particular, shows a state at the time of construction. In FIG. 1, symbol 100 represents a structure, in particular, a deteriorated steel structure, on the targeted surface of this steel structure 100 as a target for repair or reinforcement, an FRP material for repair or reinforcement is bonded. FIG. 1 shows a state where a reinforcing fiber substrate is disposed before an FRP material comprising the reinforcing fiber substrate and a matrix resin is formed (before the matrix resin is impregnated and hardened).

[0035] In the construction for repair or reinforcement shown in FIG. 1, first, a surface treatment, that removes dust or eliminates unnecessary unevenness with respect to the surface of the steel structure 100 (bonding surface 1) to be subjected to repair or reinforcement, is performed. This surface treatment is not particularly limited as long as the formation of the bonding layer in the present invention is smoothly carried out, and an ordinary cleaning for removing oil and rust, and as the case may be, surface polishing with a sandpaper or the like may be performed.

[0036] On the bonding surface 1 of the surface-treated steel structure 100, a layer of fibrous substrate 2 for forming a bonding layer and a layer of reinforcing fiber substrate 3 for forming an FRP material are laminated in this order, and after the fibrous substrate 2 is disposed so as to protrude from the edge of the reinforcing fiber substrate 3, both substrates 2 and 3 are temporarily fixed. The protrusion length of the fibrous substrate 2 is set to, for example, 5 mm or more, preferably 10 mm or more. As the form of the protruding portion 4 of the fibrous substrate 2 from the edge of the reinforcing fiber substrate 3, any of a form protruding from at least one edge of the reinforcing fiber substrate 3, preferably from the edges on both sides, and a form protruding from the substantially entire surrounding edge of the reinforcing fiber substrate 3, may be employed.

[0037] As aforementioned, the form of the fibrous substrate 2 is formed, for example, in a form of at least one of a mat-like form in which continuous fibers are randomly oriented, a mesh sheet-like form having pores, and a mat-like form composed of short cut fibers. Although the kind of fibers used for the fibrous substrate 2 is not particularly limited, for example, one equivalent to the kind of fibers used for the reinforcing fiber substrate 3 for forming the FRP material, for example, carbon fibers, glass fibers, aramid fibers, phenol fibers, combinations thereof, and the like can be exemplified, and furthermore, since the bonding layer is a layer responsible for load transfer, other organic fibers or inorganic fibers can also be used. Similarly, since the bonding layer is a layer responsible for load transfer, the layer thickness of the bonding layer after formation or the fibrous substrate 2 may not be so large, for example, as the bulk thickness before resin impregnation, the thickness may be about 0.05 to 0.70 mm. The fiber volume content of this fibrous substrate 2 with respect to the bonding layer formed after resin impregnation and hardening is preferably in the range of 5 to 40% as aforementioned.

[0038] Further, although the fibrous substrate 2 is impregnated with the resin mainly from the protruding portion 4 as described later, in order to make this resin impregnation to be performed quickly and reliably, as aforementioned, it is preferred that the sectional area of pores per unit width of a single sheet of the fibrous substrate 2, as an index showing the ease of the resin impregnation, is in a range of 0.05 mm.sup.2/mm to 1.0 mm.sup.2/mm.

[0039] Where, although it is omitted to show in the figure, the same resin as the resin to be injected described later can also be applied to the bonding surface 1 of the steel structure 100 before disposing the fibrous substrate 2 as aforementioned. Further, although the curing state of the resin at the time of moving to the next step is not limited, it can also be used for temporarily fixing the fibrous substrate and the reinforcing fiber substrate.

[0040] After the fibrous substrate 2 and the reinforcing fiber substrate 3 are disposed in a predetermined form, the fibrous substrate 2 and the reinforcing fiber substrate 3 are sealed, the pressure in the sealed interior is reduced, and the resin is injected into the decompressed sealed interior. In the embodiment shown in FIG. 1, a release substrate 5, which covers the whole of the fibrous substrate 2 and the reinforcing fiber substrate 3 and which can be peeled off after hardening the injected resin, is disposed between the above-described temporarily fixing step and the above-described sealing and decompressing step. As this release substrate 5, for example, a fluorine-based resin-coated glass fiber cloth, a polyethylene sheet, a polypropylene sheet, etc. can be used. However, in case where a resin flow sheet 6 described later is left on the surface of the FRP material and it is integrated, the release substrate 5 may be disposed on the resin flow sheet 6 and peeling off of a sealing film 7 described later may be caused by peeling off of the release substrate 5 so that the sealing film 7 can be reliably peeled off, or in case where the sealing film 7 can be peeled off even without the release substrate 5, the setting of the release substrate 5 may be omitted.

[0041] Further, in the embodiment shown in FIG. 1, a resin flow sheet 6 (also called as a resin distribution sheet) is disposed on the above-described release substrate 5 in order to quickly and evenly distribute the injected resin throughout the necessary region as described later. Because the resin from resin flow sheet 6 is impregnated into the reinforcing fiber substrate 3 and the fibrous substrate 2, a resin permeable substrate is used for the release substrate 5. As this resin flow sheet 6, for example, a nylon mesh sheet, a polyethylene mesh sheet, a polyester mesh sheet, a polypropylene mesh sheet or the like can be used.

[0042] After the release substrate 5 and the resin flow sheet 6 are disposed, the whole including the fibrous substrate 2 and the reinforcing fiber substrate 3 is covered with the sealing film 7, and the interior is sealed by the seal by a sealing material 8. As the sealing film 7, for example, a nylon film, a polyethylene film, a polyester film, a silicone sheet or the like can be used. The sealed interior 9 covered with the sealing film 7 is evacuated through a vacuum suction pump 10, and the resin is injected into the decompressed sealed interior 9. In the embodiment shown in FIG. 1, a liquefied resin 14 in a resin pot 13 provided outside is delivered to a resin injection path 12 disposed on the resin injection side 11 by suction due to the reduced pressure, and therefrom the delivered resin 14 is sent mainly toward the reinforcing fiber substrate 3 through the resin flow sheet 6 and impregnated, and it is impregnated mainly from the protruding portion 4 of the fibrous substrate 2 to the entire fibrous substrate 2. In the vacuum suction side 15, a vacuum suction path 16 is disposed, and therefrom, the exhaust from the sealed interior 9 and the vacuum suction for resin injection are performed by evacuation through the vacuum suction pump 10. The resin impregnation into the reinforcing fiber substrate 3 and the resin impregnation into the fibrous substrate 2 are performed substantially simultaneously.

[0043] After resin injection and impregnation, the injected resin is hardened and cured. Although the hardening may be carried out at a room temperature, if there is a temperature more suitable for hardening separately, the ambient temperature may be controlled at that temperature. By hardening of the resin, the FRP material (not shown) in an embodiment of the present invention in which the resin is impregnated and hardened in the reinforcing fiber substrate 3 and the bonding layer (not shown) in an embodiment of the present invention in which the resin is impregnated and hardened in the fibrous substrate 2 are formed. In the formed bonding layer, a protruding portion protruding from the edge of the FRP material, which is equivalent to that shown in FIG. 1, is left at a state that it is formed. Before or after completion of this hardening and curing of the resin, the resin flow sheet 6, the sealing film 7, the sealing material 8, the resin injection path 12 and the vacuum suction path 16, which are unnecessary for steel structure 100 performed with repair or reinforcement, are peeled off and removed together the release substrate 5.

[0044] Via the bonding layer thus formed, the FRP material is bonded to the steel structure 100 with a stable high bonding force, which makes it possible that a desired repair or reinforcement performance of the steel structure 100 is exerted.

[0045] FIG. 2 shows the bond construction and bonding method of an FRP material to a structure according to another embodiment of the present invention, and in particular, shows the state at the time of construction. In FIG. 2, as compared with the embodiment shown in FIG. 1, a fibrous substrate for intermediate suction 21 is provided in the disposition step of the reinforcing fiber substrate 3, this fibrous substrate for intermediate suction 21 is disposed so as to extend in the installation section of the reinforcing fiber substrate 3, protrude from the edge of the reinforcing fiber substrate 3 and overlap on the fibrous substrate 2 (on the protruding portion 4 of the fibrous substrate 2) at its protruding position. With respect to the installation of the fibrous substrate for intermediate suction 21, for example, as shown in the figure, the reinforcing fiber substrate 3 is divided in the thickness direction, and the fibrous substrate for intermediate suction 21 is disposed on the first-layer reinforcing fiber substrate 3, and thereon, the second-layer reinforcing fiber substrate 3 is stacked. Since the configuration is substantially the same as that shown in FIG. 1 other than the installation of the fibrous substrate for intermediate suction 21, the same symbols as those shown in FIG. 1 are referred to the same parts as those shown in FIG. 1, thereby omitting the explanation thereof.

[0046] By disposing the above-described fibrous substrate for intermediate suction 21 so as to extend through the installation section of the reinforcing fiber substrate 3 and protrude from the edge of the reinforcing fiber substrate 3, the injected resin flowing in from the protruding portion is quickly flowed through the interior of the fibrous substrate for intermediate suction 21, and can be impregnated into the reinforcing fiber substrate 3. Namely, by the resin impregnation through the fibrous substrate for intermediate suction 21, the resin impregnation to the whole of the reinforcing fiber substrate 3 in the sealed interior 9 can be promoted. Therefore, even in case where the reinforcing fiber substrate 3 for forming the FRP material is a substrate relatively thick and difficult to be impregnated with the resin in the thickness direction, by disposing the above-described fibrous substrate for intermediate suction 21 at a middle position in the thickness direction, it becomes possible to well impregnate the resin into the reinforcing fiber substrate 3 for forming the FRP material. Other operations and effects correspond to those in the embodiment shown in FIG. 1.

Examples

[0047] Hereinafter, in order to confirm the effect according to the present invention, the bonding strength of CFRP and steel materials stuck using VaRTM was confirmed in the following procedure.

[0048] [Preparation of Test Specimen]

[0049] Using two steel flat plates (elastic modulus: 206 kN/mm.sup.2) each having a thickness of 12 mm, a width of 200 mm and a length of 250 mm, setting them at a state abutted to each other at an unjoined condition, a fibrous substrate for bonding layer was set on the two steel flat plates including the abutted portion, and thereon, 7 layers of unidirectional carbon fiber sheets with different lengths for forming an FRP material in an embodiment of the present invention, Torayca cloth UM 46-40 (supplied by Toray Industries, Inc., carbon fiber amount: 400 g/m.sup.2, elastic modulus: 440 kN/mm.sup.2), were stacked.

[0050] The reinforcing fiber substrate formed by stacked carbon fiber sheets has a fixing length of 100 mm where seven layers are continued, and a taper (length: 60 mm) formed by shortening the carbon fiber sheet at intervals of 10 mm toward the end of the carbon fiber sheet.

[0051] A release substrate was placed on the above-described fibrous substrate and reinforcing fiber substrate, and thereon, a resin flow sheet was placed. A sealing tape, a tube for suction and a tube for resin injection were disposed around the substrate, and further, a sealing film was covered thereon, and then suctioned with a vacuum pump to evacuate the space covered by the sealing film.

[0052] Thereafter, while the vacuum pump was being operated, a two-component room temperature curing-type epoxy resin AUP40 (supplied by Toray ACE Corporation) was injected, and after the resin was impregnated, the vacuum pump was stopped and both tubes were sealed, and the resin was cured until being hardened.

[0053] After the resin was hardened and a carbon fiber reinforced plastic CFRP was formed, the test specimen was cut out so as to have a width of 15 mm to prepare a tensile shear bonding test specimen. Using a mechanical testing machine, the shear bonding test specimen was grasped at both ends, and the test specimen was pulled until the CFRP was peeled off.

[0054] [Method of Measuring Sectional Area of Pores of Fibrous Substrate for Bonding Layer]

[0055] The substrate thickness (mm) was measured based on JIS R 7602 carbon fiber woven fabric test method. Next, the substrate was cut out at 100 mm100 mm, and the weight per 10,000 mm.sup.2 (fiber areal weight) was measured. Next, the density thickness of the substrate was calculated from the density of the material to be used by the following equation. Then, by subtracting the density thickness from the substrate thickness, the sectional area of pores (mm.sup.2/mm) per unit width of a single sheet was calculated.

Density thickness (mm)=fiber areal weight (g/m.sup.2)fiber density (g/cm.sup.3)

Sectional area of pores of single sheet (mm.sup.2/mm)=substrate thickness (mm)density thickness (mm)

[0056] [Test Results]

[0057] The tensile load obtained by the mechanical testing machine was divided by the area calculated by multiplying the test specimen width by the fixing length, and this was taken as the bonding strength.

Bonding strength (N/mm.sup.2)=tensile load(N)/(test specimen width (mm)fixing length (mm))

[0058] As shown in Table 1, comparison of respective test levels was performed not only using an average AVE., but also, taking into account the standard deviation a, using a bonding strength generated with 99.7% probability.

[0059] As a result of the comparison, by protruding the fibrous substrate for bonding layer from the reinforcing fiber substrate, the average and the variation were reduced and the bonding strength was increased. Further, in case where a mesh sheet is used for the fibrous substrate or a resin is applied in advance to the bonding layer, the bonding strength can be further improved.

TABLE-US-00001 TABLE 1 Bonding layer Sectional area of pores Bonding strength (N/mm.sup.2) Level Substrate (mm.sup.2/mm) Specification AVE. AVE 3 1 Glass mat 0.3 Same length as that of 17.2 0.7 15.1 reinforcing fiber substrate 2 Surface mat 0.11 Same length as that of 20.2 1.2 16.6 reinforcing fiber substrate 3 Glass mat 0.3 Protruding by 1 cm from each 18.3 0.5 16.8 edge of reinforcing fiber substrate 4 Polypropylene 0.48 Protruding by 1 cm from each 22.2 0.4 21.0 mesh sheet edge of reinforcing fiber substrate 5 Glass mat 0.3 Protruding by 1 cm from each 19.0 0.4 17.8 edge of reinforcing fiber substrate VaRTM repair at condition of resin application beforehand and at state of resin uncured 6 Glass mat 0.3 Protruding by 1 cm from each 18.6 0.4 17.4 edge of reinforcing fiber substrate VaRTM repair at condition of resin application beforehand and after resin cured

[0060] The present invention is applicable not only to an infrastructure but also to repair or reinforcement for metallic materials in fields such as aircraft, cars and ships.

EXPLANATION OF SYMBOLS

[0061] 1: bonding surface [0062] 2: fibrous substrate [0063] 3: reinforcing fiber substrate [0064] 4: protruding portion [0065] 5: release substrate [0066] 6: resin flow sheet [0067] 7: sealing film [0068] 8: sealing material [0069] 9: sealed interior [0070] 10: vacuum suction pump [0071] 11: resin injection side [0072] 12: resin injection path [0073] 13: resin pot [0074] 14: resin [0075] 15: vacuum suction side [0076] 16: vacuum suction path [0077] 21: fibrous substrate for intermediate suction [0078] 100: steel structure