JP5288817B2 - Prestressed concrete pole or pile and method for producing the same - Google Patents

Description

The present invention prestressed concrete used in utility pole or pile (hereinafter referred to as "PC concrete") made of pole or pile and its manufacturing method.

  PC concrete is a construction method in which pre-stress is introduced into concrete by applying tension to PC steel wire or steel material in advance and then embedding it in concrete, then solidifying the concrete and then opening both ends of PC steel wire or steel material. Manufactured by. In recent years, a pre-tension bond method in which a rust-proof coated PC steel wire or steel material having an anticorrosion function is tensioned and then directly embedded in a concrete has been developed, and this method is expanding the range of use due to its usefulness.

  In the pretension bond method, since concrete and PC steel wire or steel material are in direct contact with each other, the progress of corrosion of PC concrete caused by moisture from defects such as cracks in the concrete becomes a particular problem.

PC concrete poles are often used as supports for power transmission / distribution and communication overhead lines. PC concrete used as a tension material for various structures is also in tension due to corrosion promotion factors (acid rain, salt water drizzle, SO _X , NO _X gas, sunlight, friction, microorganisms, etc.) depending on the environmental conditions of the installation site Corrosion prevention measures for PC concrete have become an extremely important theme because of the frequent occurrence of collapse accidents due to rapid breakage or deterioration of steel wires or steel materials in the vicinity of buried parts in the soil when corrosion occurs. .

  In particular, PC concrete poles used as tension materials in coastal or marine environments such as harbor facilities and offshore resource drilling equipment have increased salt concentration in the concrete, corroded steel wire or steel material, and generated rust. As a result, the adhesive force between the steel wire or the steel material and the concrete is lowered, and the strength of the PC concrete pole is lowered and may be broken.

As an anticorrosion measure for PC concrete poles, as described in JP-A-6-166971, a coating layer made of a thermoplastic resin made of polyethylene or the like on the surface of a PC steel wire or steel material, and an epoxy resin or the like on the surface thereof PC concrete having a rough surface layer coated with a thermosetting resin is described.
JP-A-6-166971

  However, polyethylene is excellent in corrosion resistance such as alkali resistance, but has poor adhesion to concrete. Thermosetting resins such as epoxy resins have good adhesion to concrete but have poor corrosion resistance such as alkali resistance. Further, in order to form the thermosetting resin, heating at about 180 ° C. or higher is necessary. On the other hand, a thermoplastic resin made of polyethylene or the like softens at about 150 ° C. and loses its original shape when heated to about 180 ° C. or higher. Therefore, there is a problem that a layer of a thermosetting resin such as an epoxy resin cannot be formed on a thermoplastic resin layer made of polyethylene or the like.

Further, as steel materials having salt resistance, those having components added in combination of Cu, W, Cr, Ni, Mo and the like are disclosed (Japanese Patent Laid-Open Nos. 50-23310 and 50-98420, JP, 62-188754, A).
However, since the cost increases by repeating the heat treatment, it is difficult to use.
JP 50-23310 A Japanese Patent Laid-Open No. 50-98420 Japanese Patent Laid-Open No. 62-188754

In view of the above circumstances, the present invention provides a PC concrete pole or pile manufacturing method that improves the corrosion resistance and salt resistance of a PC steel wire or steel rod.

In order to solve the conventional problems as described above, the present invention forms an inner coating layer by coating a thermosetting resin or a room temperature curable resin on the outer circumferential surface of a steel wire, and forms an inner coating layer on the outer circumferential surface of the inner coating layer. After forming an outer coating layer made of a thermoplastic resin and having a fin-like convex portion to form a linear coated steel wire, the coating layer at the end of the linear coated steel wire is peeled off, and a button is applied to the peeled portion. forming a head, the straight-coated steel wire in which the button head is formed by Haisuji a predetermined quantity according to the application as axial reinforcement, after forming a reinforcing bar cage was Haisuji the spiral muscle on the outer circumferential surface thereof After the end plate is engaged with the button head and the reinforcing bar is attached to the formwork, the end plate is gripped by a hydraulic jack to inject the concrete into the formwork while tensioning the reinforcing bar. the concrete was centrifugal molding, after centrifugal molding, the said reinforcing bar cage concrete The prestressed concrete placed within preparative heating curing, after heating aging, by releasing the tension of the reinforcing bar cage by the hydraulic jack that formed by demolding the Prestressed Concrete from the formwork, PC The present invention provides a PC concrete pole or pile having improved corrosion resistance and salt resistance of a steel wire or steel bar.

Also, the process of forming the inner coating layer by coating the outer peripheral surface of the steel wire with a thermosetting resin or room temperature curable resin, and the outer surface of the inner coating layer made of a thermoplastic resin and having a fin-like convex portion Forming a coating layer to form a linear coated steel wire; stripping the coating layer at an end of the linear coated steel wire; forming a button head on the stripped portion; and the formed the straight-coated steel wire and Haisuji a predetermined quantity according to the application as axial reinforcement, forming a reinforcing bar cage was Haisuji the spiral muscle on the outer circumferential surface of that, the end plate to the button head Engaging the rebar, attaching the reinforcing bar to the mold, gripping the end plate with a hydraulic jack and tensioning the reinforcing bar, injecting concrete into the mold, and centrifugally molding the concrete said concrete comprising the steps, the reinforcing bar cage which And heating curing the prestressed concrete placed, stroke and method of prestressed concrete pole or pile comprising a step of demolding the prestressed concrete from the mold to release the tension of the reinforcing bar cage by the hydraulic jack Is configured.

The anticorrosion-coated PC concrete pole of the present invention provides a prestressed concrete pole or pile having excellent corrosion resistance and having high corrosion resistance and salt resistance having a steel wire and a steel rod with anticorrosion coating having good adhesion to concrete. It was.

In the manufacturing method of the present invention, the PC concrete pole and / or the pile can exhibit sufficient performance even if an ordinary spiral bar is used.

Examples of the present invention will be described below in more detail with reference to the drawings. However, the present invention is of course not limited to these examples.
FIG. 1 is a schematic side view showing an embodiment of a production apparatus for PC steel wire or steel material according to the present invention, and FIG. 2 is a cross section showing an embodiment of an extruder used in the production apparatus for PC steel wire or steel material. FIG. 3 is a sectional view showing an embodiment of a forming die portion used in a PC steel wire or steel material manufacturing apparatus, and FIG. 4 is an example of a forming die used in a PC steel wire or steel material manufacturing apparatus. FIG. 5 is a perspective view showing an example of a PC steel wire or steel material, and FIG. 6 is a cross-sectional view cut along the AA plane of FIG.

  As shown in FIG. 1, first, the PC steel wire or the steel material 3 can be continuously fed from the reel 2 of the feeding device 1 through a braking device (not shown). The drawn-out PC steel wire or steel material 3 is introduced into the resin liquid combined with the curing agent of the thermosetting resin supply device 4. Here, the thermosetting resin P is applied to the PC steel wire or the steel material 3, and is heated to about 200 ° C. by the heating device 5, so that the outer surface of the PC steel wire or the steel material 3 is coated with the thermosetting resin P serving as the inner layer coating material. Is done.

  It is preferable to use an epoxy resin as the thermosetting resin. A liquid epoxy resin is used, and the coating is performed at room temperature or under heating. Epoxy resins do not cure even when heated alone, and it is necessary to add a curing agent. Since the present invention continuously forms an outer coating layer made of a thermoplastic resin on the outer peripheral surface of the inner coating layer after coating the thermosetting resin on the outer peripheral surface of the steel wire and forming the inner coating layer, For example, DDSA (Acid-Anhydride) is used as the high temperature curing agent. In addition, a diluent, a filler, or the like may be used for the epoxy resin so as to satisfy the characteristics of the cured resin.

  Further, a room temperature curable resin may be used instead of the thermosetting resin. In this case, the PC steel wire or the steel material 3 is introduced into the sprayer of the room temperature curable resin supply device instead of the thermosetting resin supply device. Here, the room temperature curable resin which becomes the inner layer covering material is sprayed by a sprayer. Therefore, the outer surface of the PC steel wire or the steel material 3 is covered so as to be wrapped with the room temperature curable resin.

As the room temperature curable liquid resin of the present invention, it is preferable to use a two-component resin made of acrylic or the like, which is classified into the following three types.
(1) Among the adhesives called second-generation acrylic adhesives (SGA), modified acrylic adhesives, and honeymoon adhesives that are classified as reactive acrylic adhesives, they are solvent-free and acrylic room temperature curable liquids. Those belonging to the adhesive can be used. For example, what has an acrylate monomer, a methacrylate monomer, and various elastomers as main components and exhibits a redox polymerization reaction type curing phenomenon by a curing agent (organic peroxide) and a curing accelerator (reducing agent) can be used.
(2) A room-temperature curable solventless acrylic reactive liquid composition, and a reactive liquid material usually called acrylic syrup can also be used. For example, those having an acrylate monomer, an acrylate oligomer, an acrylate polymer, and the like as main components and exhibiting a redox polymerization reaction type curing phenomenon with a curing agent (organic peroxide) and a curing accelerator (reducing agent) can be used.
(3) A room-temperature curable solventless acrylic reactive liquid composition that contains an acrylate monomer as the main component, and exhibits a redox polymerization reaction type curing phenomenon with a curing agent (organic peroxide) and a curing accelerator (reducing agent). The ones shown can also be used.

  In these compositions, if necessary, powders such as thermoplastic resin powder, thermosetting resin powder, inorganic material powder and scrap material are mixed to adjust the flow viscosity at the time of coating, Improvement, improvement of water stoppage, improvement of thermal stability, etc. can also be achieved. And a main component, a hardening | curing agent, and a hardening accelerator are mixed uniformly, and it extrudes and coat | covers in a pressurized state.

The PC steel wire or the steel material 3 on which the coating layer is formed is introduced into the cross head 6 of the extruder 8. As shown in FIG. 2, in the extrusion molding machine 8, polyethylene resin E, which is a thermoplastic synthetic resin material serving as an outer layer coating material heated at about 200 ° C. from the inside 81 of the melting cylinder, is extruded in a heated and melted state.

2, 3, and 4, the forming die 82 has a cylindrical shape having a circular hollow portion 83 at the center, and a large number of small concave grooves 84 are radially provided on the inner surface thereof. A coating layer is coated. Therefore, the convex part S is formed in the surface of polyethylene which is a thermoplastic synthetic resin material used as an outer layer coating material. The forming die 82 is rotated by the motor 85 with respect to the cross head 6. Therefore, as shown in FIG. 5, the convex part S formed in the surface of the polyethylene resin E which is a thermoplastic synthetic resin material used as an outer-layer coating | covering material forms a helical strip.
Thereafter, the coated PC steel wire or steel material W cooled by the cooling device 9 is wound around the reel 11 by the winding device 12 through the take-up device 10.

In order to confirm the adhesion between the steel wire and the concrete in the PC concrete pole with the anticorrosion coating of the present invention, a concrete pull-out test was conducted.
The test was carried out in accordance with “Test method for adhesion strength between rebar and concrete by pull-out test (JSTM) C2101” of the Building Materials Testing Center.

The test specimen has a fin height of 0.107 mm and 0.180 mm embedded in concrete with a compressive strength of 40.7 N · mm ² and a PC steel wire with a coating thickness of 0.296 mm, 0.228 mm, and a diameter of 7 mm. PC steel wire with a straight fin with fin heights of 0.107 mm and 0.180 mm embedded in concrete with a compressive strength of 40.7 N · mm ² and a coating thickness of 0.296 mm, 0.228 mm, diameter 7 mm A 7 mm diameter PC steel wire with indentation embedded in concrete having a strength of 40.7 N · mm ² was used.

The load applied to the test specimen was measured with a load cell and the variation of the specimen adhesion position was measured with a displacement meter using a universal tensile compression tester (Minebea TMO100000X). This test was conducted using the above equipment at the Japan Ship Quality Control Association Product Safety Evaluation Center.
In addition, as shown in FIG. 6, the steel wire with an indent I means what formed the recessed part in the surface of the steel wire. As a result, as shown in FIG. 7, the maximum adhesion stress degree of the rust-proof coated steel wire of the present invention exceeded 100% of that of the uncoated steel wire, and it was confirmed that it had high adhesion performance. Further, it is understood that the fin-like unevenness processing of the coated surface has a higher adhesion stress in the spiral (rotary fin) steel wire than in the straight fin steel wire in the length direction of the steel wire.

Next, the manufacturing method of the PC concrete pole or pile of this invention is demonstrated.
A coiled coated PC steel wire or steel material wound around a reel 11 by a winding device 12 is straightly stretched and cut to a certain length.
After cutting to a certain length, the covering layer at one end of the shaft is peeled off, and button head processing is performed on that portion. As shown in FIG. 8, one end of the coated PC steel wire or steel material W is gripped by the pressing electrode 101, and the coated PC steel wire or steel material W is gripped by the clamp electrode 102 at a constant distance from the pressing electrode 101, 500 A voltage of volt is applied to both electrodes, and the pressing electrode 101 is pressed toward the clamp electrode 102. As shown in FIG. 9, a button head B is formed at one end of the axial line on the boosting electrode 101 side for several minutes. As shown in FIG. 10, the button head B is engaged with the end plate 111 and is used for pre-stress tension of the coated PC steel wire or steel material.

The coated PC steel wire or the steel material on which the button head B is formed arranges a predetermined quantity as an axial reinforcement according to the application. On the other hand, the spiral streaks that have the coating layer made of thermoplastic resin or do not form the coating layer made of thermoplastic resin are accurately assembled by a braiding machine. The above-arranged axial and spiral bars are braided, and the axial and spiral bars are bound or welded to form a reinforcing bar rod. Next, as shown in FIG. 10, end plates 111 are provided at both ends of the reinforcing bar rod.

Next, a reinforcing bar is attached to the formwork, and the end plate is gripped by a hydraulic jack, and a tension of 40 to 100 kg / mm ² is applied at once. After storing the steel bar in the formwork, pour concrete into the formwork. The number of rotations and rotation time of the formwork are automatically controlled, and the concrete is compacted by centrifugal molding. Thereafter, curing is performed at a temperature of about 80 ° C. for 8 hours. Thereafter, the tension of the reinforcing bar is released, compressive strength is applied to the PC concrete pole and pile, and prestress is introduced. Thereafter, the mold is removed, and a PC concrete pole and pile made up of the axial reinforcement 200, the helical reinforcement 201, and the concrete 202 shown in FIG. 11 are formed as a finished product.
In the above-described embodiment, the PC concrete pole and the pile are formed in a cylindrical shape. However, the PC concrete pole and the pile can be formed in a prismatic shape and formed into a wall body by a normal method.

A linear coated steel in which a thermosetting resin is coated on an outer circumferential surface of a steel wire to form an inner coating layer, and an outer coating layer made of a thermoplastic resin and having an outer coating layer formed on the outer circumferential surface of the inner coating layer On the outer peripheral surface of the wire, a normal spiral bar that does not form a coating layer made of a thermoplastic resin is wound, and a prestressed concrete pole (improved product) obtained by centrifugally forming concrete on this wire and a helical steel wire on the outer peripheral surface of the steel wire When a bending test was performed on a prestressed concrete pole (standard product) obtained by winding and concrete-forming this, as shown in Table 1 and FIG. 12, the improved product showed the same deflection value as the standard product, The value was higher than the design breaking load, and it became clear that it had bending deformation ability.

The result of having tested about the antirust effect in the PC concrete pole of the antirust coating of this invention is demonstrated.
As shown in FIG. 13 , the sample was putty-shaped to prevent moisture from entering from a cut surface at both ends on a 300 mm long test piece in which a polyethylene resin was coated to a thickness of 300 μm on an indented steel wire having a diameter of 7 mm. The sample treated with the padding was designated as Sample 1, and the test method in which three samples 2 each having a 3 mm wide and 30 mm long covering layer were prepared in the center of Sample 1 was the JIS Z 2371 neutral salt spray test. Using the method, the test time was 2000 hours. After the test, the sample was observed for the presence of rust. The test results are shown in Table 2.

The rust-proof coated PC concrete pole of the present invention has excellent corrosion resistance against corrosion caused by salt in the concrete. When used for a PC concrete pole or pile in a coastal or marine environment, Safety and durability can be improved.

1 is a schematic side view showing an embodiment of a PC steel wire or steel material manufacturing apparatus according to the present invention. It is sectional drawing which shows the Example of the extruder used for the manufacturing apparatus of PC steel wire or steel materials. It is sectional drawing which shows the Example of the shaping | molding die part used for the manufacturing apparatus of PC steel wire or steel materials. It is sectional drawing which shows the Example of the shaping | molding die used for the manufacturing apparatus of PC steel wire or steel materials. It is a perspective view which shows the Example of PC steel wire or steel materials. It is a perspective view which shows one Example of the steel wire with an indent. It is a comparison figure which shows a concrete pull-out test in order to confirm the adhesive force of the steel wire and concrete in the PC concrete pole of the antirust coating of this invention. It is the schematic of a button head processing apparatus. It is a fragmentary perspective view which shows one Example of a button head. It is a fragmentary perspective view of the button head processing apparatus of the present invention. It is a fragmentary perspective view of the PC concrete pole and pile of this invention. It is a bending test figure of the PC concrete pole and pile of this invention. It is the schematic of the sample for testing the rust prevention effect of the PC concrete pole and pile of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Feeding device 2 Reel 3 PC steel wire or steel material 4 Thermosetting resin supply device 5 Heating device 6 Extruder crosshead 7 Extruder molding die 8 Extruder 9 Cooling device 10 Take-out device 11 Reel 12 Winding apparatus

Claims (2)

An inner coating layer is formed by coating the outer peripheral surface of the steel wire with a thermosetting resin or a room temperature curable resin, and an outer coating layer made of a thermoplastic resin and having a fin-like convex portion is formed on the outer peripheral surface of the inner coating layer. After forming the linear coated steel wire, the coating layer at the end of the linear coated steel wire is peeled off, a button head is formed on the peeled portion, and the linear coating on which the button head is formed A steel wire is used as a shaft reinforcing bar, and a predetermined quantity corresponding to the application is arranged, and a helical bar is arranged on the outer peripheral surface to form a reinforcing bar rod, and then an end plate is engaged with the button head, and the reinforcing bar rod is attached. After being attached to the mold, the end plate is gripped by a hydraulic jack, and the concrete is poured into the mold while tensioning the reinforcing bar, and the concrete is centrifugally molded. After the centrifugal molding , the reinforcing bar is Heating prestressed concrete placed in the concrete And, after heating aging, the hydraulic prestressed concrete pole or pile jack according to release tension of the reinforcing bar cage, characterized by comprising demolding the Prestressed Concrete from the formwork. A step of coating the outer peripheral surface of the steel wire with a thermosetting resin or a room temperature curable resin to form an inner coating layer;
Forming a linear coated steel wire by forming an outer coating layer made of a thermoplastic resin and having fin-shaped convex portions on the outer peripheral surface of the inner coating layer;
Peeling off the coating layer at the end of the linear coated steel wire, and forming a button head in the peeled portion;
Forming a reinforcing bar cage with the straight-coated steel wire in which the button head is formed by Haisuji a predetermined quantity according to the application as axial reinforcement, and Haisuji the spiral muscle on the outer circumferential surface of its,
Engaging an end plate with the button head;
Attaching the rebar rod to a formwork, gripping the end plate with a hydraulic jack and tensioning the rebar rod;
Injecting concrete into the mold,
A step of centrifugal molding said concrete,
Heating and curing prestressed concrete in which the reinforcing bar is disposed in the concrete;
Releasing the tension of the reinforcing bar by the hydraulic jack;
A method for producing a prestressed concrete pole or pile, comprising: demolding the prestressed concrete from the mold .

Images