JP7333241B2 - Anti-corrosion structure for steel structures and its construction method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a means and construction method for anti-corrosion technology for steel structures constructed of steel. In particular, it relates to a novel means for sacrificial corrosion protection of steel surfaces of steel structures.

Conventionally, many means have been used to prevent corrosion of underground structures such as marine steel structures, ship ballast, coastal bridges or river bridge piers, above-ground overhead pipes, steel materials buried in soil, and reinforced concrete. For example, coating of putty material, lining covering corrosion-resistant material such as vinyl chloride or thermosetting resin, anti-corrosion plating such as metal plating or thermal spraying. With these anti-corrosion measures, delamination and cracking are unavoidable because coating deterioration occurs due to the surrounding environment of the steel structure, thermal expansion and contraction, displacement, and exposure.

Unlike the means of providing a coating layer on the surface, there is known a galvanic anode anti-corrosion method that utilizes the properties of iron materials and the ionization tendency of base metals. This anti-corrosion method for galvanic anodes is a method that can be carried out in accordance with the structure to be constructed, is easy to maintain, and is an inexpensive technical means that does not require a dedicated external power supply facility. In particular, this technology is widely used as a sacrificial anode for above-ground steel structures such as bridges and port steel structures. The method has been applied conventionally.

As an example of utilizing this galvanic anode, that is, a sacrificial anode, the means disclosed in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2006-207000) is known. In this example, a water-absorbing woven fabric is brought into close contact with a magnesium plate that matches the outer shape of the object to be protected against corrosion provided on and in the ground, and galvanic corrosion is generated in the base metal due to the potential difference between iron and magnesium material. Since this method requires close contact between the magnesium plate and the object to be protected against corrosion for sacrificial corrosion protection, when a steel material with a complicated shape is used as the object, the magnesium material needs to be processed according to its shape. Therefore, if the anode body conforms to the shape of the object to be protected from corrosion, the degree of freedom in installation will be increased.

A steel material to be protected from corrosion generally has an outer curved part like H-steel, and the joint part of the steel material has an uneven shape such as bolting. In order to prevent corrosion of such a peculiarly shaped portion, it is necessary to match the peculiarly shaped portion with the anticorrosion material. For such purpose, Patent Document 2 (Patent No. 5947136) discloses that an acrylate fiber sheet containing a base metal piece having a lower potential than steel is wrapped around a steel material to be corrosion-protected, and a metal piece-containing portion is arranged on the steel surface, It also discloses a sacrificial anode piece-containing sheet having a structure in which a water absorbing sheet portion is arranged on the outer side of the sheet. This sheet enables attachment at a uniquely shaped portion corresponding to the shape of the steel material.

In addition, in Patent Document 3 (Patent No. 5461093), a sacrificial anode panel of a porous sintered body of aluminum powder and zinc powder in which a magnet and a zinc plate are positioned on the steel surface side of an object to be corroded is prepared. and the steel surface, spreading the absorbent sheet over the steel surface and then securing the panel to the steel surface with magnets. This known example is a structure in which a water-absorbing sheet is placed under a sacrificial anode panel to supply metal ions flowing from the sacrificial anode to the steel surface.

Japanese Patent Application Laid-Open No. 2006-207000 Patent No. 5947136 Patent No. 5461093

Although the technique of Patent Document 1 enhances the anticorrosion effect of the base metal, it requires a specific shape for the magnesium material as well as the anticorrosion target having a specific shape. On the other hand, a simple shape is desirable for the magnesium material so as to have versatility. Therefore, Patent Document 2 is a technique for embedding a sacrificial metal piece in a flexible fibrous body to give it flexibility to deal with an anticorrosive body having a unique shape, but it requires a special sheet containing metal. Patent Document 3, which uses such a non-special, commercially available inexpensive sheet, requires a sacrificial panel that integrates a magnet and a zinc plate with a porous sintered body. It is unsuitable for combination with a sacrificial anode such as material. In addition, when anti-corrosion work is applied to a structure to which a conventional construction method is applied, to which a magnesium plate has already been attached, even if the magnesium plate is slightly corroded and reusable, it must be removed.

Therefore, it is not only a means of sticking to the steel material to be corrosion-protected by using the conventionally used magnesium plate and commercially available sheet, but even if the object to be corrosion-protected has a complicated shape, sacrificial corrosion protection is possible. There is a demand for a low-cost technology that provides anti-corrosion effects of the generated magnesium ions and electrons associated with ionization to the surface of steel materials, maintains the natural potential of the steel surface at the anti-corrosion potential, and makes steel structures with anti-corrosion effects. .

In response to such a demand, as a result of intensive research by the inventors of the present application, gauze can be used in addition to the conventionally used means of attaching magnesium to an object to be corroded, or a magnesium plate that has already been attached can be used. By using a mesh cloth or non-woven fabric, magnesium ions and electrons associated with ionization are carried and supplied, and the anti-corrosion effect is expanded even outside the area where the magnesium plate is attached on the surface of the steel structure, and anti-corrosion is reliably maintained. I found a way to do it.

The present invention brings magnesium ions and electrons accompanying ionization into contact with an iron structure, or contacts a sufficient amount of magnesium ions and electrons accompanying ionization with a path through an electrolyte that causes corrosion of the iron structure, and adjusts the pH of the electrolyte. is raised to about 10, and the iron structure is placed in an environment where the natural potential of iron can be maintained at the anticorrosion potential. In addition, as a supply source of the magnesium ions and the electrons associated with the ionization, the corrosion products of the method of contacting the iron structure with a conventionally constructed magnesium plate with a conductive adhesive are used.

For this reason, it must be possible to keep the magnesium ions and electrons associated with ionization in contact with the iron and the electrolyte. Provided is a medium for supplyably carrying associated electrons.

The means according to claim 1 of the present invention is a corrosion-resistant structure for steel structures,
A steel material constituting a steel structure, a conductive adhesive applied to at least a part of the surface of the steel material, and a single or multiple fixedly attached to the steel material with the conductive adhesive interposed therebetween. In the anti-corrosion structure for the steel material, comprising a magnesium plate, a flexible polyester fibrous substrate, and a bituminous cover,
When used alone, the fibrous substrate covers the magnesium plate and is disposed on the surface over a larger area than the surface area of the magnesium plate, and
In the case of the plurality, the fibrous substrate connects between the plurality of magnesium plates, covers the surface, and is disposed on the surface over a wider area than the entire surface area of these magnesium plates and the connecting portion. ,
The cover is further stacked on the fibrous substrate in the single case or the fibrous substrate in the plurality of cases,
the fibrous substrate in the single case or the fibrous substrate in the plurality of cases provided on the surface with the single magnesium plate or the plurality of magnesium plates and the conductive adhesive interposed therebetween; A cover is fixed to the steel material,
The fibrous substrate in the single case or the fibrous substrate in the plurality of cases carries and supplies magnesium ions generated from the magnesium plate and electrons associated with ionization, and
The fibrous substrate carried and supplied is superimposed on at least a part of the surface of the steel material,
Maintaining the natural potential of the steel material at the anticorrosion potential over the range of the superimposed surfaces by the fibrous substrate in the single case or the fibrous substrate in the plurality of cases,
Corrosion protection is provided for at least one of a portion of the steel structure that is deformed by temperature or an external force, a portion of the gap where the steel structure is joined, and a portion of the surface that has a uniquely shaped surface on which the magnesium plate cannot be placed. characterized by an anti-corrosion structure.

The method according to claim 2 of the present invention is a method for constructing a corrosion-resistant structure of a steel structure,
A steel material constituting a steel structure, a conductive adhesive applied to at least a part of the surface of the steel material, and a single or multiple fixedly attached to the steel material with the conductive adhesive interposed therebetween. A method for constructing an anti-corrosion structure for steel material comprising a magnesium plate, a flexible fibrous substrate, and an anti-corrosion cover,
To prevent corrosion in at least one of a portion of the steel structure that is deformed by temperature or external force, a portion of the gap where the steel structure is joined, and a portion of the surface that has a uniquely shaped surface on which the magnesium plate cannot be placed. , the magnesium plate in the single case that carries and supplies magnesium ions generated from the magnesium plate that maintains the natural potential of the steel material at the anticorrosion potential over the anticorrosion range of the surface and electrons accompanying ionization There is a fibrous substrate prepared for or a fibrous substrate prepared for the magnesium plate in the plurality of cases, and a step of superimposing this fibrous substrate on at least a part of the surface of the steel material;
If said alone, covering a magnesium plate and disposing said fibrous substrate on said surface over an area greater than the surface area of said magnesium plate; or
In the case of the plurality, the fibrous substrate is arranged on the surface by connecting between the plurality of magnesium plates, covering the surface, and covering a wider area than the entire surface area of these magnesium plates and the connecting portion. and
The fibrous substrate in the single case or the fibrous substrate in the plurality of cases provided on the surface with the magnesium plate or the plurality of magnesium plates and the conductive adhesive interposed therebetween and the anticorrosion fixing a cover to the steel material, and placing the anti-corrosion cover on the fibrous substrate in the single case or on the fibrous substrate in the plurality of cases. A method of constructing a

The means according to claim 3 of the present invention is an anti-corrosion structure of a steel structure including fastening of a plurality of steel materials,
a plurality of steel materials that are overlapped and fastened; a conductive adhesive that is applied to at least a portion of the outer surface of the steel materials; and at least one of the steel materials with the conductive adhesive interposed therebetween. a magnesium plate fixedly attached to a material; a flexible polyester fibrous substrate; and bitumen for securing said fibrous substrate to said plurality of steel members and overly surrounding said fibrous substrate. A steel construction comprising a plurality of steel fasteners with a system cover,
Each of the plurality of steel materials has the fastened facing surfaces facing each other,
each of the plurality of steel materials has an end surface on the edge portion of the outer surface adjacent to the facing surface;
The fibrous substrate covers the outer surface of the magnesium plate opposite to the conductive adhesive and is provided along the outer surface around the magnesium plate so as to overlap the outer surface, and arranged to cover at least part of the end face of each of the plurality of steel materials,
Having a water retention agent between the facing surfaces of each of the plurality of steel materials,
The fibrous substrate carrying and supplying magnesium ions generated from the magnesium plate and electrons associated with ionization, and transferring the magnesium ions and electrons associated with ionization from the fibrous substrate to the water retention agent. A corrosion-resistant structure characterized by maintaining the corrosion-resistant potential of the steel material at the outer surface and the end surface covered with the fibrous substrate and the contact surface by interposing it in communication with the contact surface; be.

The method according to claim 4 of the present invention is a method for constructing a corrosion-resistant structure of a steel structure including fastening of a plurality of steel materials,
a plurality of steel materials that are overlapped and fastened; a conductive adhesive that is applied to at least a portion of the outer surface of the steel materials; and at least one of the steel materials with the conductive adhesive interposed therebetween. a flexible fibrous substrate; and an anti-corrosion cover for fixing the fibrous substrate to the plurality of steel members and surrounding the fibrous substrate. A method for constructing a corrosion-resistant structure of a steel structure including fastening of the plurality of steel materials comprising:
a step of preparing facing surfaces that face each other and are to be fastened in each of the plurality of steel materials;
preparing an end face on an edge portion of the outer surface adjacent to the facing surface of each of the plurality of steel materials;
The fibrous substrate covers the outer surface of the magnesium plate opposite to the conductive adhesive and overlaps the outer surface along the outer surface around the outer surface of the magnesium plate, and covering at least a portion of the end surface of each of the plurality of steel materials;
a step of applying a water retention agent between the facing surfaces of each of the plurality of steel materials;
a step of fastening the facing surfaces;
has
After the fastening, the fibrous substrate supports and supplies magnesium ions generated from the magnesium plate and electrons associated with ionization, and the magnesium ions and electrons associated with ionization are transferred from the fibrous substrate to the water retention agent. The anticorrosion structure is interposed in the contact surface and communicates with the fibrous substrate, and the outer surface, the end surface, and the contact surface covered with the fibrous substrate are maintained at the anticorrosion potential of the steel material. method of construction.

The means according to the first claim of the present invention is naturally applied to a new steel surface, or even to an existing magnesium plate that has already been attached, and a single or multiple magnesium plate using magnesium as a sacrificial anode. It is possible to use either of the plates, and the steel surface is covered with a fibrous substrate such as polyester plain woven fabric, non-woven fabric, or water absorbing paper made of fibers over a wider area than the magnesium plate. To provide an anti-corrosion structure which not only widens the anti-corrosion range of the steel, but also clarifies the quantitative range in which the anti-corrosion potential can be clearly maintained. Here, according to a combination of one or more magnesium plates and a fibrous substrate that carries and supplies magnesium ions and electrons associated with ionization, the steel surface is protected from corrosion over an area larger than the total surface area of the magnesium plate. can be effectively utilized. In addition, the magnesium plate has a planar shape or a limited circular arc shape, and compared to the conventional technology that was applied to steel materials with limited shapes, the flexible polyester fiber can be used even on irregularly shaped surfaces of steel materials. By taking advantage of the characteristics, the corrosion protection range can be expanded along the surface shape of the steel material. Therefore, it is possible to prevent crevice corrosion of deformed steel surfaces on which it is difficult to attach magnesium plates and joining surfaces of multiple steel materials. Since the flexibility of the fibrous substrate can be used, even if the steel material is deformed by heat or external force, the magnesium plate can be adhered to the steel material in small pieces, and the small pieces are connected by the fibrous substrate to complement the corrosion resistance. The anti-corrosion material is provided with flexibility that was not possible with a large magnesium plate, and it is possible to cope with the deformation of the steel material. In addition, since the range of corrosion protection can be expanded by overlapping a soft and flexible fiber fabric on the magnesium plate while maintaining the attached state of the conventionally applied magnesium plate, it is an inexpensive corrosion protection that is easy to install. structure can be provided. Furthermore, when a plurality of magnesium plates are used, it is possible to use small magnesium plates, and it is possible to provide an anti-corrosion structure even for steel materials with complex surface shapes, for example, bolt fastening points and deformed steel materials.

The method according to the second claim of the present invention can provide a construction method for providing the anti-corrosion structure disclosed by the means according to the first claim of the present invention. By this method, when applying the means of the present invention to a steel structure, it becomes possible to select a corrosion-resistant structure suitable for the structure of the structure or construction conditions desired by the user. In addition, this construction method makes it possible to use already attached magnesium plates.

The means according to the third aspect of the present invention provides a structure capable of imparting an anti-corrosion effect to the gaps between the end faces, particularly the edges, of a plurality of fastened steel materials and the facing faces. For example, at the splice portion of a bridge, the H-shaped fibrous substrate is wrapped along the H-shaped steel cross section, including the end faces of the upper and lower flanges of the bridge main girder and the splice plate end face, and the outer side is fixed to the main girder with an anti-corrosion cover. Therefore, it is possible to maintain a water retention agent between the splice plate and the flange surface, so the magnesium ions of the magnesium plate attached to the main girder penetrate to the splice plate, and the entire splice portion has an anti-corrosion effect. become a structure. According to this structure, even if the anti-corrosion cover deteriorates over time, is damaged, or has a structure in which the magnesium ion medium is exposed, such as an imperfect structure that does not cover the entire surface with the anti-corrosion cover, the effect of the water retention agent acts. It is possible to obtain the effect of extending the life of the anti-corrosion effect.

The method according to the fourth claim of the present invention can provide a construction method for providing the anti-corrosion structure disclosed in the method according to the third claim of the present invention. This method makes it possible to prevent corrosion even in the gaps between the fastening steel material facing surfaces of a steel structure constructed with multiple steel materials, and prevents the deterioration and breakage of the anti-corrosion cover over time, or the incomplete coverage of a part of the anti-corrosion cover. It is possible to provide construction that maintains anti-corrosion performance even if there is.

1 is a photograph of a test piece for comparison of mesh cloth bodies for applying to the anticorrosive structure of the present invention. FIG. 4 is a structural schematic diagram of an embodiment of the present invention applied to a bolted joint; It is a photograph during an experiment of the preliminary experiment of the holding function by net cloth. It is a preliminary experiment photograph showing corrosion when no net cloth is used. It is a preliminary experiment photograph showing the state of a test piece in the case of a coarse mesh cloth. It is a preliminary experiment photograph showing the state of a test piece in the case of fine mesh cloth. It is the data which verified the magnesium used by the preliminary experiment. FIG. 3 is a Pourbaix diagram for explaining the action of the present invention; It is a verification experiment that the net cloth can carry magnesium ions. It is a photograph which shows the adhesion|attachment to the gauze of an exposure test. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing of the anti-corrosion structure of 1st Example of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic perspective view of the partial cross section of the anti-corrosion structure of 1st Example of this invention. 2 is an experimental photograph showing exposure test conditions and results in Table 2. FIG. Temperature and humidity data during exposure testing. FIG. 4 is a cross-sectional view of a corrosion protection structure according to a second embodiment of the present invention; It is an anti-corrosion confirmation experiment of the structure shown in FIG. FIG. 15 shows a continuation of the anti-corrosion confirmation experiment of the structure shown in FIG. FIG. 15 shows a continuation of the anti-corrosion confirmation experiment of the structure shown in FIG. This is an experiment to determine the relationship between the material of the electron transfer medium associated with magnesium ions and ionization and the distance of the anti-corrosion range. It is a figure which shows the distance between two magnesium plates, and the relationship of an anti-corrosion potential. FIG. 16 is a cross-sectional view of the anticorrosion structure of the third embodiment to which the anticorrosion structure shown in FIG. 15 of the present invention is applied; This is an experiment to verify the anti-corrosion effect in the gap part of the steel material mating surface. This is an experiment to confirm the anti-corrosion action in the gap between the mating surfaces of steel materials. FIG. 12 is a structural diagram showing a fourth embodiment in which a water retention agent is applied to gaps between the mating surfaces of steel materials. 25 is another cross-sectional view of the structure shown in FIG. 24; FIG. It is an experimental result of the structure shown in FIG. It is a process flow figure of the anti-corrosion construction method to which this invention is applied.

BEST MODE FOR CARRYING OUT THE INVENTION An anticorrosion structure according to an embodiment of the present invention and examples of the present invention will be described below with reference to the drawings. In the detailed description of the invention, the same reference numerals and names are given to the components having the same function.

First, the applicability of commercially available fibrous substrate materials requires preliminary experiments. Therefore, in order to simply confirm the anti-corrosion effect of magnesium, an experiment was conducted to determine the ability of commercially available network substrates using magnesium hydroxide.

(Preliminary experiment to verify the support of magnesium hydroxide on the steel surface using a mesh substrate)
The following verification was carried out on the possibility of covering the steel material surface with a flexible mesh-like substrate and supporting it with the mesh-like substrate without the sacrificial magnesium hydroxide aqueous solution falling in the vertical direction. First, a test piece with a mesh cloth and a test piece without a mesh cloth were prepared as test pieces shown in FIG. 1 for comparison. A detailed description will be given below.
STKR400 manufactured by JFE Steel Co., Ltd., square column of size 60 mm, square steel pipe for general structure (JISG3466) was used as the test piece, and surface preparation st3 was performed.
Magnesium hydroxide consists of four magnesium plates of 45 mm x 45 mm attached around the steel pipe with a conductive adhesive, the surface is covered with a protective cover whose main component is bitumen rubber, and the salt concentration is 5% (weight percent) from above. of salt water was constantly flowed, and magnesium hydroxide was generated from magnesium and supplied to the surface of the steel pipe to be tested.
Two types of network-like substrates are prepared to compare their functions and effects.
For the first sample, a coarse mesh net (fiber diameter: 1 mm, mesh size: 10 mm x 5 mm) made of 100% polyester fiber (chemical name: polyethylene terephthalate) is applied to sample number 1.
For the second sample, fine mesh gauze (fiber diameter 0.3 mm, mesh size 1 mm×1 mm) made of 100% polyester fiber (chemical substance name: polyethylene terephthalate) is applied to sample number 2.
These mesh-like substrates were cut to a size of about 60 mm×60 mm and wound around the test piece. For comparison, a test piece without the mesh substrate is also prepared.

(Schematic structure of test object in preliminary experiment)
FIG. 2 is a schematic diagram of the configuration of the device under test. A magnesium plate 16 (manufactured by Gonda Metals Co., Ltd., model AZ61 polished plate, size 45 mm × 45 mm × 2 mm) is attached to the test object 12 with a conductive adhesive 14 (manufactured by Vision Development Co., Ltd., model normal temperature type). The outside is covered with a mesh substrate 18 . The network substrate 18 is extended outward from the bonding area 24 of the magnesium 16 to extend to the second test object 13 joined to the test object 12 by bolts 32 and nuts 30 . The bolts and nuts 30, 32 that join the two test objects 12, 13 form the peculiarly shaped portion 22 to which the magnesium plate 16 cannot be attached. Then, in order to confirm the supporting function of the mesh-like substrate 18, the mesh-like substrate 18 is expanded from the end portion 24 of the first test object 12 to the second test object 13, and the anti-corrosion range 26 is confirmed. Created in

(Conditions of the test atmosphere for the device to be tested in the preliminary experiment)
Dropping of salt water with a salt concentration (mass concentration) of 5% is continued for 14 days under an environmental atmosphere with a temperature of 15 ° C. and a humidity of 80% RH, and then an atmosphere temperature of 15 ° C. and a relative humidity of 40% for another 14 days. It was left in the atmosphere. FIG. 3 is a photograph of an experiment for verifying the retention function of magnesium hydroxide by a net cloth, showing the state during an actual dropping test.

(Summary Table 1 of test results in preliminary experiments)
Table 1 summarizes the results of an experiment to verify that a net cloth carrying magnesium hydroxide exhibits an antirust effect. Four types of samples were arranged side by side in each row. Here, Sample No. 1 is a case where a coarse mesh cloth is used as the mesh substrate, Sample No. 2 is a case where a fine mesh cloth is used as the mesh substrate, and Sample Nos. 3 and 4 are comparative samples. In each row, (1) presence or absence of attachment of Mg pellets to the test object, (2) presence or absence of supply of magnesium hydroxide to the surface of the test object, (3) holding magnesium hydroxide on the surface of the test object. (4) Observation evaluation of the state of rust generated on the surface of the specimen after being left in the test environment, (5) Photographs showing the state of the surface after the test, and actual photographs are shown in Figures 4 to 6. show. FIG. 4 is an experimental photograph showing the state of the test piece when no mesh cloth is wound and the state of the test piece when no magnesium hydroxide is supplied. FIG. 5 is an experimental photograph showing the state of a test piece in the case of a coarse mesh cloth. FIG. 6 is an experimental photograph showing the state of a test piece in the case of fine mesh cloth.

(Test result in preliminary experiment)
Since sample No. 4 has no anti-corrosion measures, severe corrosion naturally occurs. In sample No. 3, although sodium hydroxide was supplied and the magnesium plate of the sacrificial anode was attached, corrosion occurred in the irregular shaped portion 22, and the supply of magnesium hydroxide alone was effective in preventing corrosion. is found to be lacking. Sample No. 1, which uses a coarse mesh substrate, does not exhibit corrosion unlike Sample No. 3, so the anti-corrosion effect of magnesium hydroxide is recognized. Further, in Sample No. 2, which has finer mesh, no corrosion is observed in the peculiar shape portion 22, the end portion 24, and even the second test object 13. FIG. That is, it is clear that sample number 2 has a greater anticorrosion effect than sample number 1.

(Conclusion of Test Results in Preliminary Experiment)
In sample No. 2, the white substance covering the steel material surface of the test piece was identified as magnesium hydroxide from the X-ray diffraction data shown in FIG. -10 alkaline. With respect to such a phenomenon, in Sample No. 3, which corresponds to the conventional technology, the effect of the sacrificial anode of the magnesium plate does not extend to the peculiar shape portion 22. The area of effect is expanded. In other words, it has become clear that the use of a mesh-like substrate can broaden the range of corrosion protection more than ever before, and substantially provides the surface of the steel material with the effect of electrocoating. This phenomenon can also be understood from the Pourbaix diagram of FIG. 8, which will be described later.

(Consideration of Test Results in Preliminary Experiment)
The alkaline effect of magnesium hydroxide generated by sacrificial corrosion protection by the magnesium plate is transmitted or retained on the iron surface with gauze-like cloth, and a passivation protective film with anticorrosive effect is generated on the iron surface itself, and the alkaline effect is generated. It corresponds to the purpose of not destroying the protective film by holding it with a cloth. Normally, sacrificial corrosion protection is to lower the potential to an inactive region (1 in FIG. 8: corrosion potential) by connecting a sacrificial corrosion protection material to iron in the corrosion region (point A: natural potential) shown in FIG. purpose. In this case, when the sacrificial anti-corrosion material is exhausted, it returns to the original corrosion area (point A), so the sacrificial anti-corrosion material must be reapplied. However, in the present invention, alkaline magnesium hydroxide remains as a by-product as the sacrificial anode is consumed, so the by-product moves from point A to point 3 in FIG. That is, the point indicated by 3 in FIG. 8 is the point where black rust or a transparent and glossy film, that is, passive state is generated and maintained, so that the anticorrosion effect can be maintained.

(Confirmation experiment of preliminary experiment to verify the carrier function of the mesh-like substrate that supports the product derived from the magnesium plate)
In the preliminary experiment described above, it was confirmed that the fluid of magnesium ions was maintained on the steel surface. In other words, the magnesium plate, which is a sacrificial anode, produces magnesium hydroxide and acts as a passivation of the steel surface. It is necessary to confirm. The following example is shown as a verification that the net cloth of such a net-like substrate can carry magnesium hydroxide. FIG. 9 is a confirmatory experiment for verifying the fine mesh substrate (Sample No. 2) shown in Table 1, whose effect was confirmed in the preliminary experiment using the fluid, under static fluid conditions.

(Experimental conditions of the device under test in the confirmation experiment of the preliminary experiment)
For the confirmatory experiment of the preliminary experiment, the test procedure (items 1 to 5 in FIG. 9) will be explained according to the progress of the experiment.
In item No. 1, a conductive adhesive (manufactured by Vision Development Co., Ltd., model normal temperature type) is applied to the surface of a steel plate (manufactured by JFE Steel Corporation, model hot-rolled steel SS400 JISG3101 size 160 mm × 120 mm × 4.5 mm), magnesium After bonding a plate (Gonda Metal Industry Co., Ltd., model AZ61 polished plate, size 100 mm × 70 mm × 2.0 mm), a fine mesh substrate (gauze) of the same quality as the sample No. 2 in Table 1 is attached. . For comparison, a sample (A-1) was also prepared without using the mesh substrate.
In Item No. 2, after attaching a bitumen-based cover to the upper side of the fine mesh substrate, a matrix-like incision was made as shown in the photograph to expose the magnesium plate linearly, and then salt water (mass concentration 5% salt water ) is immersed in the soaked tray to react the magnesium plate.
Item No. 3 generates hydrogen gas and magnesium ions by immersion for 3 days. Hydrogen gas and magnesium ions flowed out from the A-1 sample without the mesh substrate, but in the A-2 sample with the mesh substrate, hydrogen gas, which was a corrosion product, passed through the gauze mesh and magnesium hydroxide was released. It is observed to remain in the gauze. In the first embodiment described above, the effect of using the 1 mm square mesh of sample number 2 as the substrate was confirmed. The significance of is confirmed.
In item No. 4, when the mesh substrate is removed from the magnesium plate, magnesium hydroxide is not supported in the A-1 sample without the mesh substrate, but the A-2 sample, which also uses the mesh substrate, is hydrated. Magnesium nodules are observed.
In Item No. 5, when the aqueous solution in the experimental tray was transferred to a beaker and the amount of magnesium hydroxide hydrate precipitated in a colloidal cloudy state was visually compared, a large amount of magnesium hydroxide flowed out from the A-1 sample without the network substrate. On the other hand, it was observed that the A-2 sample, which also used the mesh-like substrate, produced less outflow of magnesium hydroxide.

(Confirmation that the cloudy effluent obtained in the confirmation experiment of the preliminary experiment is magnesium hydroxide)
The colloidal cloudy precipitate obtained in the experiment of FIG. 9 was analyzed by X-ray diffraction. As a result, this substance was identified as magnesium hydroxide containing salt as shown in FIG. That is, the fine network substrate supports and supplies magnesium ions derived from the magnesium plate.

(Consideration of test results in confirmatory experiment of preliminary experiment)
Magnesium hydroxide obtained in the experiment shown in FIG. 9 is a diagram showing lumps of magnesium hydroxide adhering to gauze and PH in a confirmatory experiment of a preliminary experiment as an experiment to confirm the product supported by the network substrate, which will be described later. As can be seen from A in 10, the fine mesh substrate (gauze) inhibits the outflow of magnesium hydroxide and serves as a sufficient alkali supply source. At that time, as shown in FIG. 10B, the pH of the product (magnesium hydroxide) was 10.5, indicating sufficient alkalinity to remain in the passive state. From this confirmatory experiment, it was found that the network substrate used in the experiment was a magnesium ion electron conducting medium having a magnesium ion conducting portion and an electron conducting portion that contributed to the actions of the anodic reaction of magnesium and the cathodic reaction of the steel surface. It was verified that it functions as

By applying the above findings, a corrosion-resistant structure for a steel structure to which a mesh-like substrate is applied can be obtained. 11 and 12 show the structure as a first embodiment. FIG. 11 shows a cross section of the anti-corrosion structure, and FIG. 12 is a partially broken perspective view. The network substrate used here is polyester fiber having flexibility, and can follow the deformation of the steel structure due to environmental temperature or external force.

(Description of anti-corrosion structure applied to steel)
In FIGS. 11 and 12, a conductive adhesive 14 is applied to the outer surface of a steel material 12 to be corrosion-protected, a magnesium plate 16 is attached, and a mesh-like structure carrying magnesium ions and electrons associated with ionization is attached around it. To provide the substrate 18 , the outside of the plate is covered with a fine mesh substrate 18 . The mesh-like substrate 18 may be extended to reach the outer surface of the steel material 12 to be corrosion-protected, and further expanded to a range where the anti-corrosion effect of the steel material to be corrosion-protected is obtained. At least, as indicated by reference numeral 19 shown in FIGS. Further, on the outside of the mesh-like substrate 18, a bitumen-based cover, which is the cover applied in the confirmation experiment described above, is provided as an anti-corrosion cover 20. As shown in FIG. The anti-corrosion cover 20 is attached so as to sufficiently cover the mesh substrate 18 . The space provided with the mesh-like substrate 18 inside the anti-corrosion cover 20 is filled with a hydrophilic solvent that permeates from the outside and can be captured in the environment of use as an electrolyte solution. The net-like substrate 18 and the anti-corrosion cover 20 are fixed to the steel material to be corrosion-protected by bonding using a dedicated primer in a state surrounding the anti-corrosion range except for the upper surface of the mesh-like substrate 18 . Adhesion of a dedicated primer surrounding this anticorrosion range can provide an anticorrosion effect within the anticorrosion range. It should be noted that the magnesium plate used here is not limited to a magnesium plate, and can be applied as long as it is a standard product for galvanic anodes that is widely commercially available as a sacrificial anode material.

(Exposure test on the structure of the first embodiment of the present invention)
An exposure test was conducted to confirm that the structure of the present invention is effective as an anti-corrosion structure.
A general structural steel pipe (STK4002B/JISG3444 manufactured by JFE Steel Corporation, length of about 350 mm, outer diameter of about 60 mm) was used as the test sample, and surface preparation st3 was performed.
In test samples 1 to 3, the structure shown in FIG. 11 of the present invention was provided at the center of the steel pipe, and the lower end side of the gauze-like mesh substrate was partially exposed from the anti-corrosion cover and wound around the steel pipe.
For test samples 4 and 5, a zinc tape (a thin acrylic adhesive tape (zinc base sheet type) with zinc powder added, thickness 0.1 mm, width 25 mm) using zinc as a sacrificial anode material was applied twice as a comparative sample. It was wound and provided at the center of the steel pipe as with test samples 1-3.
Test sample 6 was left as it was with the steel pipe surface, and had only a black scale.
As for the test samples 1 to 6, the upper part of the steel pipe from the center part is exposed to the ground, and the opposite lower part is buried in the ground. In this test, weakly acidic brown forest soil widely distributed in Japan was used as the test soil.

(Test condition of exposure test)
FIG. 13 shows a photograph of the test sample used in the exposure test and the state of the sample after the exposure test. Among them, E in FIG. 13 is the state of samples 1 to 6 before the test, D in FIG. Later samples 1-6 are shown pulled out of the soil. The characteristics of the test samples and the test results are summarized in Table 2, and the temperature and humidity of the atmospheric environment during the exposure test are shown in FIG. The air atmosphere during this test has a temperature change width of about 15° C./day and a humidity of about 50% RH.

(Results of exposure test)
FIGS. 13A, 13B, and 13C respectively show photographs of the structure of the present invention, the structure using zinc tape, and the outer and inner surfaces of the steel pipe subjected to the exposure test of leaving the steel bare in the soil. From these photographs, it can be seen that the example in which the zinc tape is wound (B in FIG. 13) has an anti-corrosion effect compared to the bare surface (C in FIG. 13), but the steel pipe to which the structure of the present invention is applied exhibits the lightest degree of corrosion. , the surface condition of the initial stage of the steel pipe is generally maintained. From this exposure experiment, it can be confirmed that the anticorrosion effect of the present invention is superior to that of the zinc tape winding means of the prior art. To explain in more detail, steel pipes that have not been subjected to anticorrosion treatment have red rust all over the surface (including 3% salt water) in the soil (including 3% salt water) on the left side of the pipe. also remained (C in FIG. 13). The steel pipe constructed with the structure of the present invention is worn to about half of the structure, but no noticeable rust occurs in the underground pipe (black scale state without surface treatment) (Fig. 13A). . In the steel pipe wrapped with zinc tape used for comparison, red rust was observed on both the outer and inner surfaces, although the amount was less than that of the steel pipe without anticorrosion treatment, and part of the zinc tape was eroded (B in FIG. 13). .

(Consideration of exposure test)
In this exposure test, supporting evidence shown in FIG. 10 is also performed, and a qualitative consideration of the anticorrosion effect is attempted.
The reason why the anti-corrosion effect was confirmed in FIG. 10 can be understood from the Pourbaix diagram of FIG. 8 as follows. The structure of the present invention, which is joined to the steel pipe under test, uses the magnesium plate as a sacrificial electrode, and the steel pipe becomes an inactive region and is protected (A→1). Then, the magnesium hydroxide shown in FIG. 10-A is generated to alkalinize the surrounding pH (A→3). In the alkalized soil shown in FIG. 10-B, the steel pipe becomes a passive zone and is protected. In this test, a cloth was attached to the magnesium surface and one end of the cloth was connected to the outside, so that magnesium hydroxide penetrated into the soil and the soil was alkalinized. It is believed that the area of corrosion protection by alkalization is confined around the protected steel pipes because other non-protected pipes in the same vessel are sufficiently corroded. On the other hand, the galvanized tape could not be expected to be effective in areas where salt water existed, resulting in more rusting than the structure of the present invention. As can be seen from FIG. 10-A, the gauze-like network substrate inhibits the outflow of magnesium hydroxide and serves as a sufficient alkali supply source. Moreover, the pH of the product, which is magnesium hydroxide, is 10.5, which can be said to be sufficient alkalinity to remain in the passive region. In another sense, the gauze-like mesh-like substrate exerts its effect even in the inactive region indicated by reference numeral 1 shown in FIG. , a secondary effect of the gauze-like network substrate was observed.

(Structure of the second embodiment of the present invention that applies the carrier function of the mesh-like substrate and fibrous substrate that supports the magnesium plate-derived product)
The structure of the second embodiment of the present invention using a gauze-like network substrate of 1 mm×1 mm fine mesh will be described. The structure of the second embodiment of the present invention provides a structure in which the mesh-like substrate is arranged between two magnesium plates, and anti-corrosion effect is obtained even in areas where no magnesium plate is placed. This structure is an application of FIG. 11, and FIG. 15 shows a sectional view of the anticorrosion structure. That is, FIG. 15 shows the structure of the second embodiment to which the structure of the first embodiment derived from preliminary experiments is applied. In this structure, two magnesium plates 16 are placed on the surface of the corrosion-resistant steel material 12 via the conductive adhesive 14 as in the previous example, with an intermediate portion 30 of 55 mm. Then, the magnesium plate, including the space between the two magnesium plates, is covered with a mesh-like substrate 18 and further with an anticorrosion cover 20, so that not only the range 24 of the magnesium plate but also the anticorrosion range 26 including the intermediate region 30 of only the gauze 18 is provided. is a structure that obtains

(Experimental preparation of the device to be tested in the structure of the second embodiment)
For the structure of the second embodiment of the present invention, the test preparation procedure (items 1 to 3 in FIG. 16) will be described first.
In order 1,
In item number (1-4), a steel plate (manufactured by JFE Steel Corporation, model hot-rolled steel plate SS400, JIS G3101 size 160 mm×120 mm×4.5 mm) is prepared.
In item numbers (1-1) and (1-2), two magnesium plates (manufactured by Gonda Metal Industry Co., Ltd., A type AZ61 polishing plate, size 20 mm x 70 mm x 2.0 mm) is glued.
In Item No. (1-3), the conductive adhesive is extended and applied, crossed, and the iron material is exposed.
In order 2,
In Item No. (2-1), a sample (B-1) is prepared by attaching a fine mesh substrate (gauze) of the same quality as that applied to Sample No. 2 in Table 1. For comparison, prepare a test piece without gauze (photograph omitted) (B-2).
In order 3,
In item number (3-1), a bitumen-based exterior material is attached, and a notch marked with a cross is made to match the exposure of the iron material.

(Experiment progress of the device to be tested in the structure of the second embodiment of the present invention)
The experiment is performed using salt water and is described according to the progress procedure (items 4 to 6 of FIG. 17).
In order 4,
In Item No. (4-1), 5% salt water is sprayed and left for 2 days.
In Item No. (4-2), the pH of the test piece (B-1) with gauze becomes about 10 when it is brought into contact with litmus test paper.
In Item No. (4-3), the pH of the test piece (B-2) without gauze is about 7 when it is brought into contact with litmus test paper.
In order 5,
In item No. (5-1), when the self-potential of the test piece with gauze was measured, it was confirmed that the complete anti-corrosion potential (-1.159 V) was obtained at the center of the cross mark.
In order 6,
In item number (6-1), when the anti-corrosion cover (reference numeral 20 in FIG. 15) is turned over, the salt water sprayed on the cross mark reaches the magnesium plate (reference numeral 16 in FIG. 15), and the product magnesium hydroxide is completely It can be seen that the

(Experimental results of a device to be tested in the structure of the second embodiment of the present invention)
As a result of the demonstration experiment of the structure shown in FIG. 15, as shown in FIG. It was confirmed that there was no rust on the surface of (7-2) (7-4).

(Consideration of verification experiment of the structure of the second embodiment of the present invention)
From the experimental results of Figures 16 to 18, as confirmed in Item No. (7-1), even if the magnesium plate is not attached to the entire surface, if the gap is about 200 mm to about 400 mm, and if the gap is at least 100 mm For example, it can be seen that the anticorrosion effect can be exhibited by placing a plurality of magnesium plates in between and attaching a fine mesh substrate (gauze). The reason for this can be said to be the effect brought about by the magnesium ions with a strong ionization tendency supported by the gauze and the electrons associated with the ionization. In the experiments of FIGS. 16 to 18, gauze with a mesh substrate is used, but when using a fibrous substrate such as a non-woven fabric with fine fiber dispersion or a water-absorbing and evaporating paper used in a filter, magnesium ions and ionization accompanies It has a uniformly dispersed fiber structure that is advantageous for supplying electrons. For example, in an experiment using water-absorbing evaporation paper with a thickness of 0.45 mm, it was confirmed that even with the gap distance described above, the anti-corrosion potential of minus 1000 mV is sufficiently secured. Therefore, when the steel surface to be protected against corrosion is large, a fibrous substrate that supplies magnesium ions and electrons associated with ionization is placed between multiple magnesium plates along the steel surface to prevent the corrosion of magnesium ions and electrons associated with ionization. I can do it. As a result, it is possible to reduce the number of magnesium plates and reduce costs. Furthermore, even if it is necessary to remove rust to a degree of surface adjustment St3 in order to attach the magnesium plate, it is possible to reduce the cost by omitting the work of removing rust from the back surface of the fibrous substrate, ie, the gauze. .

(Differences in permeability of magnesium ions and electrons associated with ionization in various fibrous substrates)
In the structure of the second embodiment of the present invention, the mesh-like substrate was mainly examined, but as described above, in the additional experiment of the structure of the second embodiment, it became clear that the use of the water-absorbing and evaporating paper produced a more excellent effect. Ta. Therefore, by investigating the relationship between various fibrous substrates, magnesium ions, and electron permeability associated with ionization, fibrous substrates that make the present invention more effective will be clarified.
In the experimental method, a magnesium plate was attached to the end of an iron plate (SS material, thickness 3.2 mm), and the magnesium plate end was attached to each material of the fibrous substrate, which is a medium for transferring magnesium ions and electrons accompanying ionization. Measure the surface potential at a distance from the Therefore, the relationship between the distance from the magnesium plate and the potential becomes clear. Then, the material dependence of the permeability of magnesium ions and electrons associated with ionization will be understood, and a more effective medium for the present invention will be clarified. First, as shown in Experiment 1 in FIG. 19, after confirming the natural potential (minus 530 mV) of the steel test piece, the potential is measured for each distance from the end of the magnesium plate with various materials (Experiment 2 in FIG. 19). . The experimental samples were (1) polyester water-absorbing evaporation paper, (2) 100% cotton absorbent cotton, (3) 100% pulp tissue paper, and (4) high-quality copy paper with a thickness of 0.089 mm and a basis weight of about 64 g/m2. (5) 100% polyester 1 mm thick mesh gauze; (6) mixed cotton and polyester bandage.
Experimental results are shown in Table 3. Numerical values in the table are surface potentials, and the unit is minus mV. Here, the anticorrosion potential is a potential obtained by adding about 0.2 V of cathodic polarization to the natural potential (7.1.3 Cathodic protection standard of metal anticorrosion technology handbook), so the potential is added to the natural potential of iron minus 530 mV. Minus 730 mV can be judged as the corrosion protection range. This anti-corrosion range is within the range enclosed by the thick dashed line in Table 3. From the data in Table 3, it can be seen that polyester water-absorbing and evaporative paper and absorbent cotton containing cellulose as the main component have equivalent transmissibility. These results indicate that these media have about three times the permeation distance of gauze, and that both water-absorbing evaporation paper and cotton thread are equally excellent in the permeability of magnesium ions and electrons associated with ionization. Although the main components of these materials differ between polyester and cellulose, they all have a fibrous structure. Therefore, fibrous substrates, including the mesh-like substrates used in the explanations of Examples 1 to 3, can serve as effective materials for the present invention to permeate magnesium ions and electrons associated with ionization.

The data shown in Table 3 is for one magnesium plate, but if the same magnesium plates are symmetrically arranged, at least the corrosion protection potential of the solid lines 44 and 46 shown in FIG. 20 can be obtained. This figure is based on the measured values of the water absorbing and evaporating paper shown in Table 3, and shows assumed values when the magnesium plate is left-right symmetrical as shown in FIG. In FIG. 20, the left vertical axis is the right edge of the first magnesium plate, the right vertical axis is the left edge of the second magnesium plate, the horizontal axis is the distance between the first and second magnesium plates, The dotted line is plotted symmetrically with respect to the actual potential values at which the iron is in the corrosion-resistant state described in Table 3, and the dotted line is plotted at symmetrical values at the actual potential values at which the iron is in the corroded state described in Table 3. In this figure, the dashed-dotted line indicates the estimated state of the anticorrosion potential when the left and right magnesium plates are simultaneously acted upon. It can be seen from FIG. 20 that if the middle portion of the structure of FIG. 15 provided with two right and left magnesium plates is connected by a fibrous substrate, the steel surface in the middle continuously holds the anti-corrosion potential. In FIG. 20, it is shown that corrosion protection can be maintained at a distance of 300 mm between the left and right magnesium, but considering the corrosion protection potential indicated by the dashed line, it can be estimated that the corrosion protection is achieved at 300 mm or more and about 400 mm. By the way, in the structure of FIG. 15, two magnesium plates are shown. can give the effect shown.

(Application example 1 of the present invention)
In addition, in the case of a structure in which steel plates are layered, such as the splice plate of a bridge, if crevice corrosion occurs over time, it is impossible to prevent corrosion by painting, but a magnesium plate is placed on the plane of the splice plate to make it conductive. By bonding with an adhesive and gauze spread from the magnesium plate to the side of the splicing plate, it is possible to cover the entrance of the electrolyte passage to the gap and maintain the anticorrosive potential of the gap.

(Application example 2 of the present invention)
In addition, when attaching a magnesium plate for corrosion protection, it is necessary to adhere the entire anticorrosion range to the object to be protected with a conductive adhesive. Possibility of peeling off from the anticorrosion target cannot be denied. For this reason, it is possible to provide flexibility to the anti-corrosion structure by forming the magnesium plates as small pieces that can reduce the influence of deformation and filling the gaps between the magnesium plates with gauze.

(Structure of the third embodiment focusing on the steel plate overlapping portion)
As another application example of the present invention described above, another third embodiment is shown in FIG. In FIG. 21, two corrosion-protected steel materials 12 and 13 which are superimposed are joined to each other by bolts 32 and nuts 30 . A conductive adhesive 14 is applied to the outer surface of the corrosion-resistant steel material 12, and a magnesium plate 16 is attached. In this example, the magnesium plate 16 is joined to one of the steel members 12, but it can also be arranged on each of the two steel members. For example, in a gulf coast where corrosion is severe, a plurality of sacrificial anode materials can be used to further enhance the anti-corrosion effect. 16 is applied to the outer side of the magnesium plate 16 so as to include a mesh-like substrate or fibrous substrate 18 for carrying and supplying generated magnesium ions and electrons associated with ionization. is covered with a mesh-like substrate or fibrous substrate 18 . Further, an anti-corrosion cover 20 is provided on the outside of the mesh-like substrate or fibrous substrate 18 in the same manner as in FIGS. The gauze-like mesh substrate or fibrous substrate 18 used here is polyester fiber, and the anti-corrosion cover 20 is a bituminous anti-corrosion cover having hydrolysis resistance and ultraviolet resistance. The end face 35 of the laminated steel plate shown in FIG. 21 has a gap structure that is a weak point of sacrificial corrosion protection, but in the structure of FIG. With a flexible mesh-like substrate or fibrous substrate 18 and an anti-corrosion cover 20, not only the cross section of the steel material but also the uniquely shaped surface of the fastening bolt or the deformed portion of the steel material at the end, or the angle steel, channel steel, or uneven Even with deformed steel materials, the complementary effect of the corrosion protection potential transmission of these substrates (the effect was confirmed in item No. 5-1 described in the paragraph explaining the progress of the experiment of the test body in the structure of the present invention), and its Depending on the shape, the mesh-like substrate or fibrous substrate 18 acts as a carrier that carries and supplies magnesium ions and electrons associated with ionization, so that the anti-corrosion effect can be enhanced. Although one magnesium plate is shown in FIG. 21, a plurality of magnesium plates as shown in FIG. 15 can be used. Moreover, if an existing magnesium plate exists and the sacrificial state is slight, the existing magnesium plate may also be used. In FIG. 21, the fibrous substrate is shown to have a closed loop structure so as to wrap the two steel materials, but this is not restrictive, and the fibers have an open loop structure within a range that can maintain the corrosion protection potential of the steel material. A substrate may be provided. That is, even if the fibrous substrate imperfectly wraps the steel material, the effect obtained by the present invention is not denied.

(Verification experiment of the third embodiment)
Although the gap portion in the steel structure is a place with a high degree of difficulty in preventing corrosion, it is verified that the present invention is also effective for this gap structure. 22 and 23 show the verification results of the gap portion where the steel plates are joined by face-to-face contact. The steel material used is the same SS steel as the structure of the present invention described above, and this flat plate (1.6 mm x 100 mm x 50 mm) is overlapped to form a gap. Then, the whole was covered with gauze and wrapped with an anti-corrosion cover, and 5 cc of 3% salt water was poured into the gap to observe the progress. As a reference for comparison, a sample A without the magnesium plate is similarly prepared (upper part of FIG. 22, comparison photograph 1). In addition, for the sample B to be verified, three sets of magnesium plates having the same type as the structure of the present invention and having a size of about 50 mm × 50 mm were prepared. The third set was disassembled after a week, and the third set was disassembled after a month to observe the state of corrosion of the crevice surfaces. As a result, as shown in comparative photograph 2 of FIG. 22, no corrosion of the crevice surfaces was visually observed in all three sets. The fact obtained in the process of this experiment is that the anti-corrosion potential of the gap portion is maintained from the measurement of the potential measuring device as shown in the upper column of FIG. 23, and the decomposition as shown in the middle column of FIG. It is clear that the gap faces are alkaline and that the magnesium plate used is a sacrificial material as shown in the lower column of FIG. That is, the experimental results shown in FIGS. 22 and 23 indicate that magnesium ions and electrons associated with ionization permeate into the gaps to obtain anticorrosion effects.

(Structure of the fourth embodiment in which the gap structure portion is improved)
In the third embodiment described above, the steel plates, including the overlapping end faces 35, are covered with the fibrous substrate 18 and the anti-corrosion cover 20, and the gaps between the opposing mating surfaces are penetrated by magnesium ions and electron transfer media associated with ionization due to surface tension. It uses the effect of By the way, if this anti-corrosion cover deteriorates over time or is damaged unexpectedly, or if it is not possible to cover the entire structure with the anti-corrosion cover in a closed state due to the situation at the site, this structure will cause solvent leakage and dryness. Poor interstitial penetration of the moving media can occur. That is, considering the deterioration and breakage of the anticorrosion cover 20 and partial construction, it is desirable to provide a highly reliable structure that is more suitable for practical use. From such a point of view, on the premise of the structure tested in FIG. 22 described above, a new structure was examined in addition to the use of water-absorbing and evaporating paper excellent in the magnesium ion electron conduction effect. The new structure shown in FIG. 24 focuses on the preservation of the transfer medium of magnesium ions and electrons associated with ionization, and uses a combination of water-absorbing evaporation paper and a liquid water-retaining agent. In this structure, after affixing a magnesium plate 16 with a conductive adhesive 14, a plurality of steel plates (13, 14), including end faces 35, are covered with a fibrous substrate 18, and then the outside is covered. When covering with the anti-corrosion cover 20, a liquid water retention agent 39 is applied to the contact surfaces 37 of the fastened steel plates (13, 14). 25 is a view showing another cross section of FIG. 24. FIG. The water retention agent 39 in this structure is sandwiched between the steel plates (13, 14) and wrapped with the fibrous substrate 18 on the end surface 35 side. Therefore, the liquid water retention agent 39 also permeates the hydrophilic fibrous substrate 18 . Then, the magnesium ion electron conducting medium supported by the fibrous substrate 18 and this water retaining agent are mixed, and the water retaining agent penetrating the contact gap between the steel sheets carries ions and functions as a magnesium ion electron conducting medium. become a structure.

(Verification experiment of the fourth embodiment)
As sample 1, the magnesium plate was attached to the iron material in the same way as in Fig. 23, and the gap was covered with water-absorbing evaporation paper, and then covered with an anti-corrosion cover. A structure in which only one end face is open so that the end face of the laminated steel plate is not partially covered with the anti-corrosion sheet, and as sample 2, sample 1 was further coated with a liquid water retention agent on the mating surface of the magnesium plate and steel material and covered with an anti-corrosion cover. Later, three types of structures were prepared: a structure in which only one end face was open, and a structure in which only one end face was open as a reference sample, which was covered with an anti-corrosion cover by combining only iron materials. Opening one end face in this manner is substantially equivalent to tearing the anti-corrosion cover or partial construction. Then, as a means for confirming the test effect, a cycle test according to the provisions of Appendix 1 was performed using the cycle corrosion test method specified in the Japanese Industrial Standard JISK5600-7-9 Cycle D. The method was salt spray 30°C for 0.5 hours, wet 95% RH at 30°C for 1.5 hours, hot air drying at 50°C for 2 hours, hot air drying at 30°C for 2 hours, and three test samples. was studied for 28 cycles for 1 week. The liquid water retention agent used here is a well-known commercial product (Espec L, manufactured by Toyobo Co., Ltd.) for agriculture and greening, which contains polysodium acrylate as a main component.

(Experimental results of the fourth embodiment)
FIG. 26 summarizes the experimental results. First, since the reference sample does not have a magnesium plate, it does not have an anti-corrosion function, and naturally corrosion occurs due to salt water spray. By the way, it should be possible to expect the anti-corrosion effect of the gap portion as described in the third embodiment. However, in Sample 1, which corresponds to the case where the anticorrosion sheet is damaged or the case of partial construction, corrosion occurs on the steel surface in the gap portion. The reason why the structure based on the third embodiment was not able to prevent corrosion is that after 30 minutes of salt water spraying, the wetting and drying process takes 5 hours and 30 minutes. It is presumed that the anti-corrosion effect ceased to work. As proof of this, the pH was measured to be 7 (neutral), and the presence of magnesium ions (the magnesium hydroxide product is alkaline) could not be confirmed. On the other hand, in sample 2, a liquid water-retaining agent was applied to the mating surfaces of the steel materials, and the ionic electronic circuit was maintained by moisture during the wetting and drying processes, and corrosion was prevented by alkaline pH 9. The pH of the liquid water-retaining agent itself is neutral and tends to neutralize alkali. From this result, it can be said that the structure of sample 2 can supply magnesium ions to the metal surface, so even if the sealing function of the anticorrosion sheet is insufficient, the presence of the water retention agent maintains the ionic electronic circuit. Therefore, in order to prevent crevice corrosion more effectively, it is possible to increase the reliability of corrosion prevention by using a liquid water retention agent as in the fourth embodiment. Further, from the experimental results shown in FIG. 26, it was found that even if the anticorrosion sheet is not partially covered, the gaps can be protected from corrosion. That is, the anti-corrosion structure of the present invention can provide an excellent anti-corrosion effect even if it is an incomplete covering structure in which the sheet cannot be completely covered. In particular, it is difficult to construct a completely covered structure in a steel structure with a complicated structure, and it is desirable to utilize the excellent anticorrosion effect of the present invention.

(Recommended network substrate or fibrous substrate)
Polyethylene terephthalate-based hydrophilic polyester fibers are used for the network substrate applied to the present invention. Some of the fibers have an uneven surface, a water-absorbing type such as hollow fibers, or a molecular structure with reactive groups such as hydroxyl groups and carboxyl groups added, but any structure can be applied to the present invention. . As a fibrous substrate to be recommended, there is water-absorbing and evaporating paper produced by a method similar to the production of a wet-laid nonwoven fabric in which fibers are uniformly dispersed in the same manner as the production of filter paper using polyester fibers. Further, as already shown in Table 3, various fibrous substrates can be used as transfer media for magnesium ions and electrons associated with ionization. In other words, not only polyester fibers but also cellulose fibers have an excellent anticorrosion effect. However, the present invention is intended for steel structures installed in bridges and harbor facilities, and it is necessary to consider mechanical strength, exposure resistance, and the like. Therefore, a polyester material can be recommended as the fibrous substrate shown in the examples of the present invention. The application of the present invention is not denied as long as the material has

(Recommended water retention agents for combination with fibrous substrates)
The fourth embodiment described above is an experiment in which the fibrous substrate is made of water absorbing and evaporable paper, and the water retention agent is sodium polyacrylate for agriculture and greening. As described above, the structure in which this liquid water-retaining agent is applied to the joint surfaces of the steel plates provides an excellent effect of improving the corrosion resistance of the interstitial structure. From the results of this verification, it was clarified that the water retention agent permeated the joint gap between the polyester fibrous substrate and the steel material and gave the effect of transferring magnesium ions to the joint surface of the steel plate. By the way, in the experiment of the fourth embodiment, a widely commercially available liquid water retention agent containing sodium polyacrylate as a main component was used, but the water retention agent is not limited to this. For example, rather than an acrylic polymer containing a carboxyl group, an acrylamide water-absorbing polymer containing a sulfo group, which has a higher ability to absorb metal ions such as magnesium, may be used. As liquid water retention agents suitable for fibrous substrates, conductive hydrophilic polymers and hydrophilic coating agents can be used, avoiding natural substances with poor durability and materials with a strong tendency to agglomerate. In addition, if the location where the steel structure is installed is such as a harbor or river where splashes are likely to occur, and if the construction is easy, a granular or powdery water retention agent may be used, and it is not always necessary to stick to the liquid state. isn't it.

(Working means for applying the structure of the present invention to an object to be corroded)
11, 15, and 21 have been described as anti-corrosion structures for steel structures, structures to which the structural concept of the present invention can be applied are not limited to the above structures. That is, on the surface of a steel structure intended for anticorrosion, a network structure substrate or fibrous substrate that carries and supplies generated magnesium ions and electrons accompanying ionization is spread over the entire anticorrosion range of the steel surface. Work to attach. Then, as long as it is possible to cover the base with an anti-corrosion cover and fix it to a steel structure, it is also possible to apply work to steel materials with uneven and complicated shapes or gaps in steel joints. Become.

(Selection of construction method to which the present invention is applied)
FIG. 27 is a process flow for explaining the selection process of various anti-corrosion structures of the present invention in comparison with the conventional construction method. In this figure, the square frame means the work process, the diamond frame means the selection process surrounded by the dotted line frame for determining the conditions related to corrosion prevention, and the flow lines (51, 53, 55, 57, 59) in FIG. ) indicates a step flow (S1 to S15) in order of process. First, after confirming the structure to be protected against corrosion (S1), it is decided whether to prevent corrosion of multiple steel materials such as splicing plates (S2), and the non-corrosion protection of the joint surface of multiple steel materials and the corrosion protection only for the mounting range of the magnesium plate ( If it is S3), the substrate is adjusted according to the flow line 51 (S4), the size of the magnesium attachment portion is determined, the conductive polymer is applied (S5), the magnesium plate is attached (S6) and pressurized (S7), The conventional construction method is carried out in the order of primer application (S10), anti-corrosion cover (S11), intermediate coating (S12), and top coating (S13). However, when the flow line 53 is selected (S3), which expands the action range of the magnesium ions generated in a wider range than the attachment area of the magnesium plate and the electrons associated with the ionization, after the magnesium plate is attached to the corrosion-resistant steel material and fixed ( S7), while covering the magnesium plate with a net-like woven fabric substrate or a fibrous substrate (flow line (55) in FIG. 27 covers the steel surface in a wider range than the magnesium plate (S8, S9), and a primer is applied around the anti-corrosion range. After coating (S10), finishing is performed in the same manner as in the conventional process, and the anticorrosion structure shown in Fig. 11 can be obtained.When the flow line 57 is selected (S8) to save the magnesium plate and use a small magnesium plate. , the spaces between a plurality of magnesium plates are covered with a net-like woven fabric substrate or a fibrous substrate (S15), a primer is applied around the anti-corrosion area (S10), and the finishing steps (S11, S12, S13) are performed according to the flow line 57. 15. By the way, when intending to prevent corrosion of the multiple steel materials to be fastened in step S2, the corrosion protection process (flow line 52) of the joining surfaces of the multiple steel materials is selected in step S3. , the base material including the joint surface is adjusted (S4) as necessary, a water retention agent is applied to the joint surface (S14) or coated, that is, a film is formed, and the steel material end surface including the intervening gap portion is covered with a fibrous substrate. (S15), the anti-corrosion structure shown in Figures 24 and 25 is obtained according to the same process (flow line 59) as flow line 57. Flow lines 57 and 59 indicate the case where a plurality of magnesium plates are used. However, in the case of the structure shown in FIG. It is also possible to replace the use of the magnesium plate with the use of both side edges of one magnesium plate.

DESCRIPTION OF SYMBOLS 12, 13... Corrosion-proof steel material 14... Conductive adhesive 16... Magnesium plate 18... Mesh-like base, fibrous base 20... Corrosion-proof cover,
24... Area where magnesium plate is attached 26... Anti-corrosion area of anti-corrosion object 37... Contact fastening surface of steel material 39... Water retention agent

Claims (2)

An anti-corrosion structure for a steel structure including a plurality of steel material fastenings,
a plurality of steel materials that are overlapped and fastened; a conductive adhesive that is applied to at least a portion of the outer surface of the steel materials; and at least one of the steel materials with the conductive adhesive interposed therebetween. a magnesium plate fixedly attached to a material; a flexible polyester fibrous substrate; and bitumen for securing said fibrous substrate to said plurality of steel members and overly surrounding said fibrous substrate. A steel construction comprising a plurality of steel fasteners with a system cover,
Each of the plurality of steel materials has the fastened facing surfaces facing each other,
each of the plurality of steel materials has an end surface on the edge portion of the outer surface adjacent to the facing surface;
The fibrous substrate covers the outer surface of the magnesium plate opposite to the conductive adhesive and is provided along the outer surface around the magnesium plate so as to overlap the outer surface, and arranged to cover at least part of the end face of each of the plurality of steel materials,
Having a water retention agent between the facing surfaces of each of the plurality of steel materials,
The fibrous substrate carrying and supplying magnesium ions generated from the magnesium plate and electrons associated with ionization, and transferring the magnesium ions and electrons associated with ionization from the fibrous substrate to the water retention agent. A corrosion-preventive structure characterized by maintaining the corrosion-protective potential of the steel material on the outer surface and the end face covered with the fibrous substrate and the contact surface by interposing it in communication with the contact surface.
1. A method of constructing a corrosion-resistant structure for a steel structure comprising fastening a plurality of steel members, the method comprising the steps of:
a plurality of steel materials that are overlapped and fastened; a conductive adhesive that is applied to at least a portion of the outer surface of the steel materials; and at least one of the steel materials with the conductive adhesive interposed therebetween. a flexible fibrous substrate; and an anti-corrosion cover for fixing the fibrous substrate to the plurality of steel members and surrounding the fibrous substrate. A method for constructing a corrosion-resistant structure of a steel structure including fastening of the plurality of steel materials comprising:
a step of preparing facing surfaces that face each other and are to be fastened in each of the plurality of steel materials;
preparing an end face on an edge portion of the outer surface adjacent to the facing surface of each of the plurality of steel materials;
The fibrous substrate covers the outer surface of the magnesium plate opposite to the conductive adhesive and overlaps the outer surface along the outer surface around the outer surface of the magnesium plate, and covering at least a portion of the end surface of each of the plurality of steel materials;
a step of applying a water retention agent between the facing surfaces of each of the plurality of steel materials;
a step of fastening the facing surfaces;
has
After the fastening, the fibrous substrate supports and supplies magnesium ions generated from the magnesium plate and electrons associated with ionization, and the magnesium ions and electrons associated with ionization are transferred from the fibrous substrate to the water retention agent. The anticorrosion structure is interposed in the contact surface and communicates with the fibrous substrate, and the outer surface, the end surface, and the contact surface covered with the fibrous substrate are maintained at the anticorrosion potential of the steel material. How to construct.

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