JP2018009334A - Reinforcement method of steel chimney - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reinforcement method of steel chimney capable of reducing work period and reinforcement cost by simplifying reinforcement work requiring no welding work etc. which is required in conventional methods, which may be applied to reinforcement works of a steel chimney which has an outer surface temperature of 80°C or more.SOLUTION: The reinforcement method of steel chimney is method to integrally bond a fiber sheet 1 including reinforcement fibers to the outer surface of a cylinder body 100 of the steel chimney using an adhesive 105. The glass transition temperature of the adhesive is 80°C or more; and the viscosity of which is 3000 to 50000 mPa by s.SELECTED DRAWING: Figure 9

Description

  The present invention uses a sheet-like reinforcing fiber-containing material containing continuous reinforcing fibers (hereinafter referred to as “fiber sheet”) to repair and reinforce a steel chimney (hereinafter including repair and reinforcement). (This is called “reinforcement”).

  Steel chimneys are used for flue gas at steelworks and thermal power plants. There are three main parts that require maintenance in the steel chimney: a steel cylinder, a cylinder support member that supports the cylinder, and a lining inside the cylinder. Among them, the cylinder body and the cylinder body supporting member bear the frame as a chimney structure, and when deterioration progresses, it becomes a factor such as breakage or collapse due to its own weight, earthquake, or strong wind. In addition, the occurrence of cracks has been reported in the barrel, and there are concerns about problems such as gas leakage.

  In order to solve these problems, the steel chimney should be reinforced immediately, but the reinforcement plan is not progressing. In particular, the following two points are mainly cited as the obstructive factors for the reinforcement of the cylinder. One is a so-called patch plate reinforcement method (hereinafter simply referred to as “conventional method”), which is generally performed in the past, in which a reinforcing iron plate is welded to a cylinder to reinforce, so that the reinforcement work process is performed. It is complicated, and there is a tendency that the degree of difficulty and cost are high, including temporary construction and safety measures. Another is that the conventional method has a long work process, and the period until the completion of the repair work is prolonged under the restriction of the regular repair work.

  On the other hand, Patent Document 1 discloses a method for reinforcing a steel chimney in which longitudinal and lateral ribs are installed in a cross beam shape on the inner peripheral surface of a cylinder and a carbon fiber wire is wound around the outer peripheral surface of the cylinder. doing. In this method, the reinforcing work itself is extremely complicated, and the construction period is unavoidable.

  In addition, as described in Patent Document 2, conventionally, a reinforcing method (CFRP method) using carbon fiber reinforced plastic (CFRP) has been adopted as a general and effective means for reinforcing a reinforced concrete (RC) chimney. Reinforcement of RC chimneys is proceeding relatively efficiently.

  Patent Document 3 discloses an elastic layer formed by applying a fiber sheet using, for example, carbon fiber or aramid fiber as a reinforcing fiber on the surface of a steel structure and applying a polyurea resin to the surface of the steel structure. A method of reinforcing a steel structure by bonding with an adhesive is disclosed.

  Although it is described in Patent Document 3 that a chimney is included as a steel structure, the surface temperature of a steel structure as a reinforced body is increased to about 60 ° C. by direct sunlight in midsummer. It is a steel structure reinforcement method that is supposed to be a road bridge. Therefore, the adhesive of the fiber sheet uses an adhesive whose glass transition temperature is adjusted to 70 ° C to 100 ° C.

  According to the results of our experiments, steel chimneys used for flue gas at steelworks, thermal power plants, etc., even if linings as thermal insulation materials are laid inside, It has been found that the surface temperature may exceed 80 ° C. and reach 100 ° C., and the reinforcing method described in Patent Document 3 cannot be immediately adopted for reinforcing a steel chimney.

Japanese Patent Laid-Open No. 5-321482 JP-A-5-332031 Japanese Patent No. 5380551

  Therefore, as a result of studying the techniques described in the conventional method and the patent document, the present inventors applied the CFRP method to the steel chimney reinforcement method, thereby making it easy and inexpensive to maintain the steel chimney. I thought it would be possible to proceed. First, as a result of summarizing the expected effects by comparing the characteristics of the conventional method and the CFRP method, it was found that the effects such as reduction of safety risk, reduction of temporary construction, and cost reduction associated therewith are expected. .

That means
・ Safety (conventional method)
The backing plate (iron plate) which is a reinforcing member is heavy and requires labor for transportation and installation. Moreover, despite the great risk of falling, welding work at a high place is required.
(CFRP method)
It is a bonding method using lightweight carbon fibers, which can reduce the lifting of heavy objects and is advantageous in terms of safety and disaster prevention. That is, reinforcement and repair work can be simplified and safety can be improved.
・ Temporary and heavy machinery (conventional method)
Large heavy equipment is required, and the time for restraining heavy equipment is long.
(CFRP method)
The capacity of the unloading heavy machine can be small, and the unloading restraint time is short. That is, it is possible to reduce the size of heavy machinery and shorten the usage time of heavy machinery.
・ Construction period (conventional method)
If there are many on-site work in high places and forced repair work is required due to the influence of gas, etc., the construction period will be longer.
(CFRP method)
CFRP, etc. that has a track record in a short construction period can be used, and the reinforcement and repair work processes can be shortened. That is, the safety risk due to collapse and the production hindrance due to damage can be reduced early.
・ Cost (conventional method)
Large temporary construction and safety measures such as fire curing, falling curing, wind protection measures for safety and quality assurance are necessary.
(CFRP method)
Lightweight and welding-less construction method allows temporary and safety measures to be reduced. That is, repair costs can be reduced.
・ Other (conventional method)
There is concern that the internal lining may be damaged by field welding.
(CFRP method)
The inner lining is not damaged because it is weldless. Therefore, the concern about corrosion from the inside of the cylinder can be reduced.

  The inventors of the present invention have compared the problems of the prior art and the features of the CFRP method, and by using an adhesive having specific properties as an adhesive for bonding the fiber sheet to the cylinder. The present inventors have found that the CFRP method can be employed to effectively reinforce the steel chimney. The present invention is based on such novel findings by the present inventors.

  The object of the present invention can be effectively applied to the reinforcement of a high-temperature steel chimney having a chimney outer surface temperature of 80 ° C., and does not require a reinforcement work such as a welding work required in the conventional construction method. Another object of the present invention is to provide a method for reinforcing a steel chimney capable of shortening the construction period and reducing the reinforcement cost by simplifying the reinforcement work.

The above object is achieved by the method for reinforcing a steel chimney according to the present invention. In summary, the present invention provides a method for reinforcing a steel chimney in which a fiber sheet containing reinforcing fibers is bonded and integrated on an outer surface of a steel chimney cylinder with an adhesive.
The adhesive is
Glass transition temperature is 80 ° C or higher,
A viscosity of 3000 to 50000 mPa · s,
This is a method for reinforcing a steel chimney.

  According to an embodiment of the present invention, the adhesive is a room temperature curable epoxy resin, an epoxy acrylate resin, an acrylic resin, an MMA resin, a vinyl ester resin, an unsaturated polyester resin, or a photocurable resin.

  According to another embodiment of the present invention, before the fiber sheet is bonded onto the outer surface of the cylinder, the surface of the cylinder is subjected to a ground treatment and / or a primer is applied.

  According to another embodiment of the present invention, a polyurea resin putty agent is applied and cured on the outer surface of the cylinder to form an elastic layer, and then the outer surface of the cylinder on which the elastic layer is formed is formed. The fiber sheet is bonded with the adhesive.

According to another embodiment of the present invention, the polyurea resin putty agent has a tensile elongation at curing of 400% or more, a tensile strength of 8 N / mm ² or more, and a tensile modulus of 60 N / mm ² or more and 500 N / mm ² or less. It is.

  According to another embodiment of the present invention, before forming the elastic layer on the outer surface of the cylinder, the surface of the cylinder is ground and / or a primer is applied.

  According to another embodiment of the present invention, the fiber sheet is a fiber sheet in which continuous reinforcing fibers aligned in one direction are fixed to each other with a wire fixing material.

  According to another embodiment of the present invention, the fiber sheet includes a plurality of continuous fiber reinforced plastic wires that are impregnated with a matrix resin in a reinforced fiber, and are arranged in a slender shape in the longitudinal direction. It is a fiber sheet fixed with a fixing material.

  According to another embodiment of the present invention, the fiber sheet is a fiber sheet obtained by impregnating a continuous reinforcing fiber sheet aligned in one direction with a resin and curing the resin.

  According to another embodiment of the present invention, the fiber sheet is laminated and adhered to the surface of the cylinder in a plurality of layers, and is integrated with the cylinder.

  According to another embodiment of the present invention, the reinforcing fibers include inorganic fibers such as carbon fibers, glass fibers, and basalt fibers; metal fibers such as boron fibers, titanium fibers, and steel fibers; and further, aramid, PBO (polyparaffin). (Phenylene benzbisoxazole), polyamide, polyarylate, polyester, and other organic fibers are used singly or in combination with a plurality of organic fibers.

  According to the present invention, the present invention can also be effectively applied to reinforcement of a high-temperature steel chimney having a chimney outer surface temperature of 80 ° C. Moreover, the reinforcing method of the present invention does not require reinforcing work such as welding work required in the conventional method, and can shorten the work period and reduce the reinforcing cost by simplifying the reinforcing work.

FIG. 1 is a perspective view of a part of a reinforced steel chimney for explaining a method for reinforcing a steel chimney according to the present invention. FIGS. 2A to 2D are perspective views of a part of a reinforced steel chimney for explaining a bonding mode of fiber sheets in the method for reinforcing a steel chimney of the present invention. FIG. 3 (a) is a perspective view of a part of a reinforced steel chimney for explaining the bonding mode of the fiber sheet in the steel chimney reinforcement method of the present invention, and FIG. 3 (b) is a fiber sheet. It is a perspective view of a part of steel chimney for explaining other modes of adhesion. FIG. 4 is a view showing an embodiment of a fiber sheet that can be used in the steel chimney reinforcement method of the present invention. FIG. 5 is a view showing another embodiment of a fiber sheet that can be used in the steel chimney reinforcing method of the present invention. FIG. 6 is a perspective view showing an embodiment of a fiber sheet that can be used in the steel chimney reinforcing method of the present invention. FIG. 7 is a cross-sectional view of an example of a fiber reinforced plastic wire constituting a fiber sheet that can be used in the steel chimney reinforcement method of the present invention. FIGS. 8A and 8B are perspective views showing another embodiment of the fiber sheet that can be used in the steel chimney reinforcement method of the present invention. FIG. 9 is a process diagram illustrating a specific example of the steel chimney reinforcement method of the present invention. FIG. 10 is a process diagram for explaining another specific example of the steel chimney reinforcement method of the present invention. FIG. 11 is a process diagram for explaining another embodiment of the method for reinforcing a steel chimney according to the present invention. FIG. 12 is a diagram illustrating the configuration of a bending strength test apparatus for demonstrating the steel chimney reinforcement method of the present invention. FIG. 13 is a diagram showing a bending test result of a reinforced steel material for comparing the present invention with a comparative example.

  Hereinafter, the method for reinforcing a steel chimney according to the present invention will be described in more detail with reference to the drawings.

Example 1
Referring to FIG. 1, the steel chimney 10 shows only the cylinder 100 in FIG. 1, but as described above, the steel cylinder 100, the cylinder support member that supports the cylinder 100, and the cylinder The interior lining is provided, and in particular, the steel cylinder 100 is likely to deteriorate, and its safety management is required. The tubular body 100 has a thickness of 10 mm or more, an outer diameter of 2 m or more, and a height exceeding 100 m. Moreover, although the lining for heat insulation, acid resistance, etc. is constructed inside, the outer surface 101 of the cylinder 100 is 80 degreeC or more, and may exceed 100 degreeC depending on the case. In such a cylinder 100 of the steel chimney 10, when deterioration such as generation of cracks progresses, it becomes a factor such as breakage or collapse due to its own weight, earthquake, or strong wind. Therefore, the reinforcement work of the steel chimney 10 is required. According to the method for reinforcing a steel chimney according to the present invention, the steel chimney 10 has a tubular body 100 in which the fiber sheet 1 including the continuous reinforcing fiber f is bonded to the outer surface of the steel chimney 10 with an adhesive. And integrated.

Here, the feature of the reinforcing method of the steel chimney 10 according to the present invention is that the fiber sheet 1 containing the reinforcing fiber f is bonded and integrated with the adhesive on the outer surface of the tubular body 100 of the steel chimney 10. In the chimney reinforcement method,
As an adhesive
Glass transition temperature is 80 ° C or higher,
A viscosity of 3000 to 50000 mPa · s,
Is to use an adhesive.

  According to the present invention, preferably, before the fiber sheet 1 is bonded to the cylindrical outer surface 101 with an adhesive, the cylindrical surface 101 is ground-treated, and further, a primer is applied to the cylindrical surface 101. it can. Further, an elastic layer can be provided by applying a polyurea resin putty agent between the tubular body 100 and the fiber sheet 1.

  Next, the fiber sheet 1 used in the present invention will be described.

(Fiber sheet)
In the present invention, various forms of fiber sheets 1 can be used. Although the Example of the fiber sheet 1 is specifically described as sheet specific examples 1 to 3, the form of the fiber sheet 1 used in the present invention is not limited to those shown in these sheet specific examples.

Sheet Example 1
FIG. 4 shows an embodiment of the fiber sheet 1 that can be used in the present invention. The fiber sheet 1 is a non-resin-impregnated fiber sheet 1A configured in a sheet shape by aligning continuous reinforcing fibers f in one direction.

That is, 1 A of fiber sheets can be set as the structure which hold | maintained the reinforcing fiber sheet which consists of the continuous reinforcing fiber f arranged in one direction with the wire fixing material 3 used as a mesh-like support body sheet | seat. For example, when carbon fibers are used as the reinforcing fibers f, for example, a plurality of unimpregnated single fiber bundles in which 6000 to 24000 single fibers (carbon fiber monofilaments) f having an average diameter of 7 μm are converged in parallel in one direction. Used to align. The fiber basis weight of the carbon fiber sheet 1A is usually 30 to 1000 g / m ² .

  Carbon obtained by impregnating the surfaces of the warp yarn 4 and the weft yarn 5 constituting the mesh-like support sheet as the wire fixing material 3 in advance with a low melting point type thermoplastic resin, and arranging the mesh-like support sheet 3 in a sheet shape The fibers are laminated on one or both sides of the fiber and heated and pressed to weld the warp 4 and weft 5 portions of the mesh-like support sheet 3 to the carbon fiber sheet.

  In addition to the biaxial configuration, the mesh-shaped support sheet 3 is formed by orienting glass fibers in three axes, or only the wefts 5 orthogonal to the carbon fibers arranged in one direction. It can also be bonded to the so-called uniaxially oriented carbon fibers that are arranged and aligned in the form of a sheet.

  As the yarn of the wire fixing material 3, for example, a double-structured composite fiber having a glass fiber in the core and a low-melting-point heat-fusible polyester around it is also preferably used. .

Sheet specific example 2
Further, as shown in FIG. 5, the fiber sheet 1 is obtained by impregnating a resin fiber with a reinforcing fiber sheet in which a plurality of reinforcing fibers f are aligned in one direction, for example, a fiber sheet 1A as shown in FIG. A fiber sheet (so-called FRP plate) 1B in which is cured.

  In the fiber sheets 1A and 1B described in the sheet specific examples 1 and 2, the reinforcing fiber f is not limited to carbon fiber, but is inorganic fiber such as glass fiber or basalt fiber; boron fiber, titanium fiber, steel Metal fibers such as fibers; and organic fibers such as aramid, PBO (polyparaphenylene benzbisoxazole), polyamide, polyarylate, and polyester; it can.

  In addition, as the resin Re in the case of the fiber sheet 1B in the sheet specific example 2, a thermosetting resin or a thermoplastic resin can be used. As the thermosetting resin, a room temperature curable epoxy or a thermosetting epoxy is used. Resin, vinyl ester resin, MMA resin, acrylic resin, unsaturated polyester resin, phenol resin, or the like is preferably used, and nylon, vinylon, or the like can be suitably used as the thermoplastic resin. The resin impregnation amount is 30 to 70% by weight, preferably 40 to 60% by weight.

Sheet specific example 3
Further, as shown in FIG. 6 and FIG. 7, the fiber sheet 1 has a plurality of continuous fiber reinforced plastic wires 2 having a small diameter and impregnated with a matrix resin R, and arranged in a slender shape in the longitudinal direction. Moreover, the fiber sheet 1C which fixed each wire 2 with the wire fixing material 3 mutually can also be used.

  The fiber reinforced plastic wire 2 has a substantially circular cross-sectional shape (FIG. 7A) having a diameter (d) of 0.5 to 3 mm, or a width (w) of 1 to 10 mm and a thickness (t) of 0. It can be a substantially rectangular cross-sectional shape (FIG. 7B) of 1 to 2 mm. Of course, other various cross-sectional shapes can be used as necessary.

  As described above, in the fiber sheet 1 </ b> C that is aligned in one direction and formed into a slender shape, the wires 2 are close to and separated from each other by a gap (g) = 0.05 to 3.0 mm to form the wire fixing material 3. Fixed.

  Also in the case of the fiber sheet 1C, the reinforcing fibers f include inorganic fibers such as carbon fibers, glass fibers, and basalt fibers; metal fibers such as boron fibers, titanium fibers, and steel fibers; and further, aramid, PBO (polyparaphenylene). Benzbisoxazole), polyamide, polyarylate, polyester, and other organic fibers can be used alone or in a mixture of a plurality of organic fibers. The matrix resin R impregnated in the fiber reinforced plastic wire 2 can be a thermosetting resin or a thermoplastic resin. As the thermosetting resin, a room temperature curing type or a thermosetting type epoxy resin, A vinyl ester resin, an MMA resin, an acrylic resin, an unsaturated polyester resin, a phenol resin, or the like is preferably used, and nylon, vinylon, or the like can be preferably used as the thermoplastic resin. The resin impregnation amount is 30 to 70% by weight, preferably 40 to 60% by weight.

  Moreover, as a method of fixing each wire 2 with the wire fixing material 3, for example, as shown in FIG. 6, a plurality of wires arranged in a sled shape in one direction using wefts as the wire fixing material 3 are used. It is possible to adopt a method of driving and knitting a wire rod in the form of a sheet consisting of two, that is, a continuous wire rod sheet at a constant interval (P) perpendicular to the wire rod. The driving interval (P) of the weft yarn 3 is not particularly limited, but is usually selected in the range of 10 to 100 mm in consideration of the handleability of the produced fiber sheet 1.

  At this time, the weft 3 is, for example, a yarn obtained by bundling a plurality of glass fibers or organic fibers having a diameter of 2 to 50 μm. Moreover, nylon, vinylon, etc. are used suitably as an organic fiber.

  As another method of fixing each wire 2 in a slender shape, a mesh-like support sheet can be used as the wire fixing material 3 as shown in FIG.

  That is, a plurality of wires 2 arranged in the form of a sheet in the form of a sheet, that is, one side or both sides of a wire sheet is made of, for example, glass fiber or organic fiber having a diameter of 2 to 50 μm. It can also be set as the structure supported by the mesh-shaped support body sheet | seat 3 made into the structure similar to having demonstrated in Example 1. FIG.

  Furthermore, as another method of fixing each wire 2 in a slender shape, as shown in FIG. 8 (b), as the wire fixing material 3, for example, a flexible belt material such as an adhesive tape or an adhesive tape is used. Can be used. The flexible strip 3 has one side or both sides of a plurality of fiber reinforced plastic wires 2 in a direction perpendicular to the longitudinal direction of each fiber reinforced plastic wire 2 arranged in the form of a sheet. Paste and fix.

  That is, as the flexible strip 3, an adhesive tape or adhesive tape such as a vinyl chloride tape, a paper tape, a cloth tape, and a nonwoven fabric tape having a width (w1) of about 2 to 30 mm is used. These tapes 3 are usually stuck in a direction perpendicular to the longitudinal direction of each fiber reinforced plastic wire 2 at intervals (P) of 10 to 100 mm.

  Furthermore, as the flexible strip 3, the thermoplastic resin such as nylon or EVA resin is formed into a strip and is heat-bonded to one side or both sides in the direction perpendicular to the longitudinal direction of the wire 2. Is done.

  In addition, although the length (L) and the width (W) of the fiber sheet 1 (1A, 1B, 1C) formed as described above are appropriately determined according to the size and shape of the structure to be reinforced. From the viewpoint of handling, generally, the total width (W) is 100 to 1000 mm. Moreover, although the length (L) can manufacture a strip-shaped thing about 1-5 m, or a thing 100 m or more, it cuts and uses it suitably at the time of use. It is also possible to manufacture the fiber sheet 1 with a length (L) of about 1 to 5 m and a width W of about 1 to 10 m.

(Reinforcing method)
Next, a method for reinforcing the steel chimney 10 will be described. According to the present invention, the steel chimney 10, that is, the tubular body 100 is reinforced using the fiber sheet 1 manufactured as described above. With reference to FIG.9 and FIG.10, the Example of the reinforcement method of this invention is described according to the reinforcement | strengthening process procedure as the work specific examples 1 and 2 concretely.

Work example 1
(First step)
As shown in FIGS. 9 (a) and 9 (b), the weakened portion 101a of the surface to be reinforced (that is, the surface to be bonded, which is the outer surface of the tube 100) 101 of the steel tube 100, as necessary, It is removed by grinding means 50 such as a disk sander, sand blast, steel shot blast, water jet or the like, and the adherend surface 101 of the cylinder 100 is subjected to a base treatment.

(Second step)
As shown in FIG. 9C, an epoxy-modified urethane resin primer 103 is applied to the surface 102 subjected to the ground treatment. The primer 103 is not limited to the epoxy-modified urethane resin type, and is appropriately selected such as an MMA type resin.

  In addition, the application | coating process of the primer 103 can also be skipped.

(Third step)
As shown in FIGS. 9D and 9E, an adhesive 105 is applied to the surface 102 subjected to the ground treatment, and the fiber sheet 1 is pressed and adhered to this surface. A predetermined number of fiber sheets 1 are bonded as required.

  According to the method for reinforcing a steel chimney 10 of the present invention, for example, as the fiber sheet 1, it is possible to use the fiber sheet 1A produced by aligning the reinforcing fibers f described in the sheet specific example 1 in one direction. It can be integrated on the outer surface of the cylinder 100 with an adhesive 105. At this time, simultaneously with the adhesion of the fiber sheet 1A to the cylindrical body 100, the adhesive (matrix resin) impregnation of the fiber sheet 1A with this adhesive can also be performed. Of course, when the fiber sheet 1B made of the FRP material is used as the fiber sheet 1, the fiber sheet 1B is formed into a predetermined shape in accordance with the shape of the cylinder 100 with the adhesive 105 on the cylinder surface 102. Affixed.

  When reinforcing the tubular body 100, for the region that mainly receives the bending moment and axial force, by adhering the orientation direction of the reinforcing fibers to substantially coincide with the principal stress direction of the tensile stress or compressive stress generated by the bending moment, It is possible for the fiber sheet 1 to effectively bear the stress and to efficiently improve the load resistance of the structure. In FIG. 1 described above, the orientation direction of the reinforcing fibers f is affixed along the longitudinal direction (axial direction) of the cylindrical body 100, and FIG. 2A shows the orientation direction of the reinforcing fibers f in the circumferential direction of the cylindrical body 100. (A direction perpendicular to the axial direction).

  In addition, when bending moments act in two orthogonal directions, as shown in FIG. 2 (b), two or more layers so that the orientation direction of the reinforcing fiber f of the fiber sheet 1 substantially coincides with the principal stress generated by the bending moment. The load resistance can be improved efficiently by stacking and bonding the fiber sheets 1 orthogonally.

  In addition, in order to reinforce the cylinder in the twisting direction, as shown in FIG. 2C, the orientation direction of the reinforcing fibers f can be affixed by being shifted by an angle θ from the axis of the cylinder. In this case, reinforcement in the twist direction is most effective when the angle θ is 45 °. If the tubular body 100 receives a twist in both directions, as shown in FIG. 2 (d), a fiber sheet having a fiber array direction angle θ1 and a fiber array are provided to reinforce the tubular body in both directions. A predetermined number of each of the direction angles θ2 can be laminated and attached to the outer surface of the cylinder. The angles θ1 and θ2 may be the same or different.

  In the above description, as shown in FIG. 1, the fiber sheet 1 is formed by reinforcing the tubular fiber 100 with the rectangular fiber sheet 1 having the circumferential length (W) and the axial length (L) of the tubular body 10. Although it has been described that a predetermined number of sheets are laminated and pasted in the region, as shown in FIGS. 3A and 3B, the fiber sheet 1 is wound around and pasted around the cylinder body 100 (circumferential direction). May be. In this case, the fiber sheet 1 may be formed by winding a long fiber sheet having an axial length (L) of the cylinder 10 in the circumferential direction of the cylinder 10 in FIG. As shown in (b), the fiber sheets 1 having the circumferential length (W) and the axial length (L) of the tubular body 10 may be pasted continuously with overlapping regions Wd in the circumferential direction. good.

Next, the adhesive 105 that characterizes the present invention will be described. The steel chimney 10 according to the present invention may reach 80 ° C. or more, and in some cases, 100 ° C. or more on the outer peripheral surface of the tubular body 100. Therefore, according to the present invention, as the adhesive 105, in order to achieve a good reinforcing effect even at high temperatures,
(1) Glass transition temperature (Tg) is 80 ° C. or higher,
(2) Viscosity is 3000 to 50000 mPa · s,
It is necessary to be.

  That is, with regard to the glass transition temperature (Tg), in the present invention, the cylinder 100 that is the casing of the steel chimney 10 may be 80 ° C. or higher, and the adhesive 105 has a glass transition temperature (Tg). If the temperature is not higher than 80 ° C., the adhesive 105 is softened and a predetermined strength cannot be obtained.

In terms of viscosity, in the present invention, the appropriate viscosity required for the adhesive is the following test:
(1) Standing a steel plate heated to 80 ° C. vertically, applying an adhesive (viscosity was adjusted by adjusting the amount of thickener added) on the surface of the steel plate, and applying A test for checking the sagging property (workability) of the adhesive and the impregnation property of the adhesive to the fiber sheet when the fiber sheet is bonded to the steel sheet.
(2) A tensile test in which a fiber reinforced resin (FRP) is produced by impregnating a fiber sheet with an adhesive having a changed viscosity and the tensile strength of FRP due to the impregnation property of the adhesive is observed.
(3) Two fiber reinforced resins (FRP) produced by impregnating a fiber sheet with resin are joined with an adhesive whose viscosity is changed so that part of them overlap, and the joint strength caused by the adhesive See the tensile test.
Therefore, it was judged from workability, impregnation property and joint strength. That is, the workability is judged by the above test (1), the impregnation property is judged by the above tests (1) and (2), and the joint strength is judged by the above test (3).

  If the viscosity is less than 3000 mPa · s, the impregnation property and joint strength are good, but the adhesive applied to the vertical surface will sag and the amount of resin necessary for fiber sheet adhesion cannot be secured on the construction surface, so appropriate construction Difficult to do.

  When the viscosity is greater than 50000 mPa · s and less than or equal to 100000 mPa · s, the workability and impregnation are good, but the joint strength of the fiber reinforced resin (FRP) that has been cured by resin impregnation as the base material to be joined is the base material. It will be below the strength.

  Further, when the viscosity is greater than 100,000 mPa · s, the impregnation property is lowered, the fluff of fibers is confirmed by visual observation, and the strength as FRP is not exhibited.

  Table 1 below summarizes the judgments based on the results of the tests (1), (2), and (3).

  That is, from the results of the above tests, in the present invention, as described above, the appropriate viscosity required for the adhesive is 3000 to 50000 mPa · s.

  As described above, the surface of the steel chimney 10, that is, the cylinder 100, rises to a temperature of about 80 ° C. due to the temperature of the exhaust gas and the direct sunlight in summer in Japan. For this reason, it has been found that with the adhesive of the conventional specification as described in Patent Document 3, the adhesive softens and the necessary reinforcing effect may not be obtained.

Therefore, as the adhesive 105, the above characteristics (1) and (2), that is,
(1) Glass transition temperature (Tg) is 80 ° C. or higher,
(2) Viscosity is 3000 to 50000 mPa · s,
By using an adhesive having the characteristics as described above, it is possible to avoid a situation where the reinforcing effect cannot be obtained by exhaust gas and sunlight irradiation, to obtain a sufficient reinforcing effect, and the fiber sheet has a breaking strength. It is possible to avoid peeling from the surface of the cylinder before reaching.

  Examples of the adhesive 105 having the above characteristics include a room temperature curing type epoxy resin, an epoxy acrylate resin, an acrylic resin, an MMA resin, a vinyl ester resin, an unsaturated polyester resin, a photocurable resin, and the like. Room temperature curable epoxy resins and MMA resins are preferred.

In this example, an epoxy resin adhesive was used. The epoxy resin adhesive is provided by a two-component type of a main agent and a curing agent, and an example of the composition is as follows.
(I) Main agent: An epoxy resin is used as a main component, and a material containing a silane coupling agent as necessary is used as an adhesion enhancing agent. The epoxy resin can be, for example, a bisphenol type epoxy resin, in particular, a rubber-modified epoxy resin for imparting toughness, and a reactive diluent, a thixotropic agent, a thickener, etc. can be added depending on the application. May be.
(Ii) Curing agent: containing amines as a main component, optionally containing a curing accelerator and using a colorant or the like as an additive, the main component epoxy resin: the amine equivalent ratio of the curing agent is Each is 1: 1. The amines can be aliphatic amines including, for example, metaxylene diamine and isophorone diamine. The epoxy resin having such a composition has a glass transition temperature of 80 ° C. or higher (for example, 100 ° C.) and a viscosity of 3000 to 50000 mPa · s (for example, 8000 to 30000 mPa · s).

  The adhesive 105 has been described as being applied onto the cylinder 100, but of course, it can also be applied to the fiber sheet 1 and on both the surface of the cylinder 100 and the adhesive surface of the fiber sheet 1. It may be applied.

  Moreover, as above-mentioned, when there is much required reinforcement amount, it is possible to adhere | attach the multiple layers fiber sheet 1 on the cylinder surface. However, if the fiber sheets 1 having a plurality of layers are laminated and bonded, stress concentration occurs at the end portion, and the peel fracture resistance may decrease.

  Therefore, in order to prevent peeling failure, it is preferable to change the sheet length (L) of the fiber sheet 1 of each layer as shown in FIG. For example, the length of the fiber sheet 1 to be laminated in a plurality of layers is shortened in order as it goes to the outer layer separated from the cylindrical surface 102, and the end portion 1a of the fiber sheet 1 is laminated stepwise. The shifting length (h) of the end 1a is suitably about 30 mm to 300 mm. For example, good results could be obtained by bonding the sheet end 1a so as to be shortened by 100 mm.

  That is, by reducing the length (L) of the fiber sheet 1 to be laminated in a plurality of layers by reducing the outer layer by about 30 to 300 mm in order and laminating the end 1a in a stepped manner, the stress concentration at the sheet end 1a is reduced, It is possible to improve the peeling resistance.

Work example 2
With reference to FIG. 10, another working example of the embodiment of the reinforcing method of the present invention will be described.

  This work example 2 has the same work process as the above-described work example 1, except that the fiber sheet 1 is bonded to the adhesive as shown in FIGS. 10 (d), (e), and (f). Before adhering to the surface of the tube body 100, a polyurea resin putty agent is applied to the surface 102 of the tube body 100, if necessary, to form an elastic layer 104, and then the fiber sheet 1 is formed. It differs in that it is bonded to the surface of the cylinder 100 by an adhesive via the elastic layer 104. This will be described in more detail below.

(First step, second step)
In this work specific example 2, as in work specific example 1, the first step and the second step are performed as shown in FIGS.

  That is, in the first step, as shown in FIGS. 10A and 10B, the surface to be reinforced of the steel tube body 100 (that is, the surface to be bonded which is the outer surface of the tube body 100) as necessary. The brittle portion 101a of 101 is removed by a grinding means 50 such as a disk sander, sandblast, steel shot blast, water jet or the like, and the adherend surface 101 of the barrel 100 is subjected to a base treatment.

  In the second step, as shown in FIG. 10C, an epoxy-modified urethane resin primer 103 is applied to the surface 102 that has been subjected to the ground treatment. The primer 103 is not limited to the epoxy-modified urethane resin type, and is appropriately selected such as an MMA type resin.

  In addition, the application | coating process of the primer 103 can also be skipped.

(Third step)
As shown in FIG. 10 (d), a polyurea resin putty agent 104 is applied to the base-treated surface 102 at a required thickness (T) and cured to form an elastic layer 104. The coating thickness (T) is appropriately set according to the unevenness on the surface of the adherend surface 102 and the thickness T of the fiber sheet 1, but is generally about T = 0.2 to 10 mm.

A polyurea resin putty agent having a low elastic modulus, that is, a material for forming the elastic layer 104 (elastic layer forming material) includes a main agent, a curing agent, a filler, an additive, and the like. It is as follows.
(I) Main agent: A prepolymer having an isocyanate (for example, 4, -4′diphenylmethane diisocyanate) as a reaction component and having a terminal residual isocyanate adjusted to 1 to 16 parts by weight with NCO wt%.
(Ii) Curing agent: A curing agent containing an aromatic amine (for example, an amine value of 80 to 90) is used as a main component, and the NCO: amine ratio of the main agent is calculated at 1.0: 0.55 to 0.99 parts by weight. Use what was done. Furthermore, p-toluenesulfonic acid salt etc. can also be included as a hardening accelerator.
(Iii) Filler: Meteorite powder, a habit modifier, and the like are included, and are appropriately blended in an amount of 1 to 500 parts by weight.
(Iv) Additives: Colorants, viscosity modifiers, plasticizers and the like are included, and are appropriately blended in an amount of 1 to 50 parts by weight.

Here, the polyurea resin putty agent has a tensile elongation at curing of 400% or more (usually 400 to 600%), a tensile strength of 8 N / mm ² or more (usually 8 to 10 N / mm ² ), and a tensile elastic modulus. 60 N / mm ² or more and 500 N / mm ² or less (usually 60 to 100 N / mm ² ).

If the elastic modulus is less than 60 N / mm ² , necessary reinforcement stress transmission cannot be performed, and conversely, if it exceeds 100 N / mm ² , particularly if it exceeds 500 N / mm ² , there is a problem that elongation performance is insufficient. .

  Moreover, in order to use polyurea resin as a putty agent, the viscosity at 2 revolutions by a BM type viscometer at 23 ° C. is 200 to 700 Pa · s, and at 20 revolutions, it is in the range of 60 to 100 Pa · s. It is desirable that the thixotropic index, that is, the ratio of the measured values of viscosity at different rotational speeds by a rotational viscometer (viscosity at 2 rotational speeds / viscosity at 20 rotational speeds) is 4 to 7.

  That is, when the viscosity is less than 60 Pa · s and the thixotropic index is less than 4, sagging occurs after coating, and it becomes difficult to apply the smoothness of the coated surface and the ceiling surface and wall surface, and conversely, the viscosity is 100 Pa. If the thixotropic index is larger than s and exceeds 7, the resin is hard, there is a problem in mixing, and it is difficult to apply smoothly.

  The polyurea resin putty agent having the above characteristics used in this working example 2 can exhibit stable performance from −15 ° C. to 80 ° C. Therefore, the polyurea resin putty agent can be used as an elastic layer forming material for reinforcing steel chimneys, and can achieve peeling prevention and repair reinforcement effects that are not affected by temperature, and is extremely suitable for use in steel chimney reinforcement construction methods. I knew I would get it.

(4th process)
As shown in FIGS. 10E and 10F, when the polyurea resin putty is cured and the elastic layer 104 is formed, the adhesive 105 is applied onto the elastic layer 104, and the fiber is applied to the surface. The sheet 1 is pressed and bonded to the surface 102 of the concrete structure 100 to be reinforced via an elastic layer 104. This process is the same as in the case of the working example 1.

  That is, as the adhesive 105, an adhesive having the same characteristics (1), (2), and (3) as those described in the specific working example 1 is used.

  Although the adhesive 105 has been described as being applied on the elastic layer 104, it can of course be applied to the fiber sheet 1, and on both the surface of the elastic layer 104 and the adhesive surface of the fiber sheet 1. It may be applied.

  Next, the following experiment was conducted in order to demonstrate the operational effect of the steel chimney reinforcement method according to the present invention.

Experimental example (present invention)
In the experimental example according to the present invention, the fiber sheet 1 was used to reinforce the steel material as the tubular body 100 according to the bonding method. Moreover, the fiber sheet 1 used in this experimental example was the fiber sheet 1A having the configuration described as the sheet specific example 1 with reference to FIG.

As the reinforcing fiber f in the fiber sheet 1A, pitch-based carbon fiber strands with an average diameter of 10 μm and a convergent number of 6000 resin-impregnated pitch-based carbon fiber strands were aligned in one direction so as to have a fiber basis weight of 300 g / m ² to form a sheet. A biaxial mesh-like support 3 made using glass fiber was welded to one side of the sheet-like reinforcing fiber to obtain a fiber sheet 1A.

  The fiber sheet 1 made as the fiber sheet 1A thus produced had a width (W) of 500 mm and a length (L) of 50 m. In this example, such a fiber sheet was appropriately cut out and used.

  Next, the steel material 100 as a cylindrical body using the fiber sheet 1 was reinforced by the same fiber sheet bonding method as described with reference to FIG. 9 as follows. However, in this experimental example, the fiber sheet 1 was stuck on both side surfaces of the steel material 100.

  As shown in FIG. 12, the steel material 100 used in this experimental example is a structural steel plate having a cross section of a rectangular shape with a width W100 of 25 mm and a thickness T100 of 9 mm, and an overall length L100 of 600 mm. It was.

First, in this experimental example, both surfaces of the steel material 100 were polished by shot blasting to obtain an appropriate rough surface. An epoxy resin having the above-described composition having a glass transition temperature of 100 ° C. and a viscosity of 9700 mPa · s is used as an adhesive 105 on the surface-treated surface 102 of the steel material 100 (in this experimental example, a plurality of fiber sheets 1 are used). Since the layers were laminated, it was applied at a coating amount of 0.4 kg / m ² as an undercoat for each layer. The fiber sheet 1 has a width W1 of 25 mm and a total length L100 of 400 mm, similar to the steel material 100, from the fiber sheet 1A.

  That is, the fiber sheet 1 is arranged in the center in the longitudinal direction on each side of both sides of the steel material 100, and after lightly pressing the epoxy resin coated surface, the fiber sheet 1 has a width of 100 mm and a diameter 10 mm plastic roller of about 100 N. It was moved while applying the pressing force of. The fiber sheet 1 was formed by laminating a total of seven layers of the fiber sheet 1 having the above-described configuration with the adhesive 105. Specifically, Nippon Steel & Sumikin Materials Co., Ltd. “Carbon Fiber Sheet C830” (trade name)), and further, “Carbon Fiber Sheet C160” (trade name) made by Nippon Steel & Sumikin Materials Co., Ltd. 2 layers were laminated.

  The epoxy resin is in a state of exuding from the gaps between the fibers of the fiber sheet 1 by rolling from the fiber sheet 1 with a plastic roller, and is stuck to the steel material 100 without any holding. There was no peeling.

In this experimental example, since the fiber sheet 1 was laminated in a plurality of layers, the epoxy resin 105 was applied to the surface of the fiber sheet 1 at a coating amount of 0.2 kg / m ² as a top coat for each layer, and the surface was flattened with a rubber spatula. Finished. Thereafter, it was cured at room temperature for 1 week. It was possible to adhere to the steel material 100 very well without generating any voids on the sticking surface of the fiber sheet 1.

  As a comparative example, the fiber sheet 1 was produced with the same structure and material as the above experimental example, except that the adhesive 105 for bonding the fiber sheet 1 to the steel material surface was different. The adhesive 105 used in the comparative example was an epoxy resin having a glass transition temperature of 70 ° C. and a viscosity of 4200 mPa · s.

  With respect to the fiber sheet reinforced steel material 100 of this experimental example and the fiber sheet reinforced steel material 100 of the comparative example manufactured as described above, both ends of the steel material 100 are gripped by a chuck as shown in FIG. A tensile test was performed using a tensile test apparatus. The test atmosphere temperature was 80 ° C. Moreover, in the fiber sheet reinforced steel material 100 which is a test body, the longitudinal direction center part (position where L100 / 2 is 300 mm) of the fiber sheet (CFRP) 1 adhered to both side surfaces, the width direction center part (W100, W1 is 12.5 mm position), and the steel material 100 and the fiber sheet (CFRP) when a strain gauge SG is installed at the longitudinal center of both sides of the steel material 100 (position where L100 / 2 is 300 mm) and a tensile load is applied. ) The amount of strain at the center of the specimen 1 was measured.

  FIG. 13A shows the test result of this experimental example, and FIG. 13B shows the test result of the comparative example. The following can be understood from the load / strain graph shown in FIGS.

  In the present experimental example (FIG. 13A), even when the ambient temperature is 80 ° C., the adhesive is not softened. Therefore, even when the load increases, It can be seen that the strain of the fiber sheet (CFRP) 1 matches, that is, the load applied to the steel material is completely transmitted to the fiber sheet (CFRP) 1 and achieves the reinforcing effect as calculated. On the other hand, in the comparative example (FIG. 13B), an epoxy resin adhesive having a glass transition temperature of less than 80 ° C. (Tg = 70 ° C.) is used as the adhesive, so the ambient temperature is 80 ° C. Then, as the adhesive softens and the load increases, the strain deviation increases between the fiber sheet (CFRP) 1 and the steel material 100, and the load cannot be transmitted to the fiber sheet (CFRP). It shows that the reinforcement effect as calculated cannot be achieved. That is, as compared with the present invention, in the comparative example, sufficient reinforcement of the steel material is not achieved as the temperature rises, and the fiber sheet (CFRP) 1 is finally peeled from the steel material 100.

  Thus, according to the method for reinforcing a steel chimney according to the present invention, it was revealed that the steel chimney 10 can be effectively reinforced.

DESCRIPTION OF SYMBOLS 1 Fiber sheet 2 Fiber reinforced plastic wire 3 Wire material fixing material (weft, mesh support sheet, flexible strip)
10 Steel chimney 100 Steel cylinder 103 Primer 104 Polyurea resin putty agent (elastic layer)
105 Adhesive

Claims (11)

In the method of reinforcing a steel chimney, in which a fiber sheet containing reinforcing fibers is bonded and integrated on the outer surface of the steel chimney cylinder with an adhesive,
The adhesive is
Glass transition temperature is 80 ° C or higher,
A viscosity of 3000 to 50000 mPa · s,
A method for reinforcing a steel chimney, characterized in that   The steel according to claim 1, wherein the adhesive is a room temperature curable epoxy resin, an epoxy acrylate resin, an acrylic resin, an MMA resin, a vinyl ester resin, an unsaturated polyester resin, or a photocurable resin. How to reinforce the chimney.   The surface of the cylindrical body is ground-treated and / or a primer is applied before adhering the fiber sheet onto the outer surface of the cylindrical body. Steel chimney reinforcement method.   A polyurea resin putty agent is applied on the outer surface of the cylinder and cured to form an elastic layer, and then the fiber sheet is bonded to the outer surface of the cylinder on which the elastic layer is formed with the adhesive. The method for reinforcing a steel chimney according to claim 1 or 2, wherein: 5. The polyurea resin putty agent has a tensile elongation at curing of 400% or more, a tensile strength of 8 N / mm ² or more, and a tensile modulus of 60 N / mm ² or more and 500 N / mm ² or less. A method for reinforcing a steel chimney according to claim 1.   The steel according to claim 4 or 5, wherein a surface of the cylindrical body is subjected to a ground treatment and / or a primer is applied before the elastic layer is applied on the outer surface of the cylindrical body. How to reinforce the chimney.   The steel sheet according to any one of claims 1 to 6, wherein the fiber sheet is a fiber sheet in which continuous reinforcing fibers aligned in one direction are fixed to each other by a wire fixing material. Reinforcement method.   The fiber sheet is a fiber sheet in which reinforced fibers are impregnated with a matrix resin, and a plurality of cured continuous fiber reinforced plastic wires are aligned in a slender shape in the longitudinal direction, and the wires are fixed to each other by a wire fixing material. The method for reinforcing a steel chimney according to any one of claims 1 to 6.   7. The fiber sheet according to claim 1, wherein the fiber sheet is a fiber sheet in which a continuous reinforcing fiber sheet aligned in one direction is impregnated with a resin and the resin is cured. Steel chimney reinforcement method.   The steel sheet stack according to any one of claims 1 to 9, wherein the fiber sheet is laminated and bonded to the surface of the cylinder in a plurality of layers, and is integrated with the cylinder. Reinforcement method.   The reinforcing fiber is an inorganic fiber such as carbon fiber, glass fiber or basalt fiber; metal fiber such as boron fiber, titanium fiber or steel fiber; and further, aramid, PBO (polyparaphenylene benzbisoxazole), polyamide, polyarylate A method for reinforcing a steel chimney according to any one of claims 1 to 10, wherein organic fibers such as polyester are used alone or in combination with a plurality of organic fibers.

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