JP5888743B2 - Corrosion protection method and corrosion protection structure of steel structure - Google Patents

Description

  The present invention relates to a coating anticorrosion method and a coating anticorrosion structure for steel structures such as steel sheet piles exposed to the marine environment, and more particularly to a coating anticorrosion method and a coating anticorrosion structure for a severely splashed tidal zone. Among steel structures, steel sheet piles may be irregularly deformed due to impacts or earthquakes during placement, but in this case as well, good corrosion protection can be maintained for a long time by covering without gaps. The present invention relates to a method and a corrosion protection structure for a steel structure.

Conventionally, as an anticorrosion method for existing steel structures exposed to the marine environment, petrolatum coating, underwater-curing coating, mortar coating, and the like have been performed (see Non-Patent Document 1).
The petrolatum coating is a composite type anticorrosion method using a petrolatum-based anticorrosive material for the anticorrosion layer and using a protective cover made of plastic or corrosion resistant metal as the protective layer.
Underwater-curing coating is an anticorrosion method in which an epoxy-based paint or putty that cures even in water is applied to a steel material.
The mortar coating is a corrosion prevention method in which a mold made of plastic or corrosion-resistant metal is attached to an anticorrosion object, and mortar that hardens even in seawater is injected into the mold.
More recently, as a new anticorrosion method, an electric current is applied to an anticorrosion object to form a thick electrocoating on the surface to prevent corrosion (see Patent Document 1), and rust prevention is applied to resins such as urethane. There is an organic coating method (see Patent Document 2) in which an agent or the like is added to coat an anticorrosive object in an uncured state.

In the conventional anticorrosion method described above, the petrolatum coating has advantages such as that a large machine is not required for implementation and the construction method is simple, but the angle of the anticorrosion object such as a steel sheet pile is acute. When deformation is involved, there is a drawback that a gap is likely to be formed between the coating layer and the surface of the anticorrosion object, and the anticorrosion of the portion becomes insufficient.
Underwater-curing coatings can be applied in the same way as painting, but because the necessary base preparation grade is high, if paint or putty is not applied immediately after blasting, adhesion failure may occur, and it is a coating film. There is a drawback that it is vulnerable to the impact of drifting objects.
Although the mortar coating is excellent in strength as a coating material, a large-scale heavy machine is required for the coating operation, and the mass applied to the anticorrosion target is considerably large.
Since it is necessary to energize a large current until the film is formed, the electrodeposition method is difficult to apply to the upper part of the tidal zone, and it is also necessary to always supply a little anticorrosion current to maintain the film.
The organic coating method is similar to petrolatum coating as a system and uses a resin such as urethane instead of petrolatum as an anticorrosion layer. It will be greatly affected.

"Port Steel Structure Corrosion Prevention and Repair Manual" (2009 edition) November 2009, issued by Coastal Development Technology Research Center, pages 55-59

JP 2011-252190 A JP 2000-282500 A

  The object of the present invention is to improve the above-described drawbacks of the conventional corrosion prevention method for steel structures, and to create a gap between the corrosion protection layer and the surface of the corrosion protection object even if the corrosion protection object is irregularly deformed. Without being able to coat the anticorrosion layer evenly on the surface of the anticorrosion object, it can be in a good anticorrosion state, and is not easily damaged even when subjected to external force, and can maintain a good anticorrosion state for a long period of time, It is another object of the present invention to provide a coating corrosion prevention method and a coating corrosion prevention structure for a steel structure that do not require an on-site coating operation or a large machine and are excellent in on-site workability.

The present inventors have made various studies on the formation of the anticorrosion layer disposed on the surface of the anticorrosion object with the water-expandable resin, and the anticorrosion object is deformed by the water-swellable resin that absorbs and expands. Even though the anticorrosion layer follows the deformation, it is difficult to uniformly expand when the water-swellable resin absorbs and expands. As a result, wrinkles occur on the surface of the anticorrosion layer, and the surface of the anticorrosion object and the anticorrosion There was a problem that a gap was generated between the layers and the anticorrosion layer could not be uniformly coated on the surface of the anticorrosion object.
As a result of further earnest research to solve the above problems, the present inventors have constituted a corrosion prevention layer disposed on the surface of the anticorrosion object, which is composed of a surface layer having a low water-swelling property and an inner layer having a high water-swelling property. The present inventors have found that the above-mentioned problems are solved and the coating corrosion prevention method and the coating corrosion prevention structure of the steel structure that achieve the above object are obtained by adopting a two-layer structure.

This invention is made | formed based on the said knowledge, and provides the coating | coated anticorrosion method and coating | coated anticorrosion structure of the following steel structure.
In a corrosion prevention method for a steel structure in which an anticorrosion layer is provided on the surface of an object to be protected and a protective cover is attached on the anticorrosion layer, the anticorrosion layer is made of a paste-like urethane system having different water-absorbing polymer contents. A two-layer structure composed of an inner layer and a surface layer composed of a cured layer of resin, wherein the inner layer is a corrosion-resistant layer containing more water-absorbing polymer than the surface layer, and the two-layered corrosion-proof layer is the protective cover. A method for coating corrosion protection of a steel structure, characterized in that it is integrally attached to a body to be protected.

  In a coated anticorrosion structure of a steel structure comprising an anticorrosion layer disposed on the surface of an anticorrosive body and a protective cover attached on the anticorrosion layer, the anticorrosion layer has a water-absorbing polymer content. A two-layer structure composed of a hardened layer of different pasty urethane resin and a surface layer, wherein the inner layer contains more water-absorbing polymer than the surface layer. Covered anti-corrosion structure.

  According to the present invention, it is possible to improve the drawbacks of the conventional corrosion prevention method for steel structures, without causing a gap between the anticorrosion layer and the surface of the anticorrosion object, even if the anticorrosion object is irregularly deformed. The anti-corrosion layer can be uniformly coated on the surface of the anti-corrosion object, it can be in a good anti-corrosion state, it is not easily damaged even when subjected to external force, and the good anti-corrosion state can be maintained for a long time. Therefore, it is possible to provide a coating anticorrosion method and a coating anticorrosion structure for a steel structure that is excellent in workability on site without requiring a coating operation or a large machine.

FIG. 1 is a cross-sectional view showing a preferred embodiment of a coated anticorrosive structure for a steel structure according to the present invention. FIG. 2 is a cross-sectional view showing a state before the anticorrosion layer absorbs and expands in the embodiment shown in FIG. FIG. 3 is a graph showing the daily change in mass of the anticorrosion layers of Test Examples 11, 12, and 13 after being immersed in seawater. FIG. 4 is a graph showing the daily change in diameter of the anticorrosion layers of Test Examples 11, 12, and 13 after immersion in seawater. FIG. 5 is a graph showing the daily change in thickness of the anticorrosion layers of Test Examples 11, 12, and 13 after being immersed in seawater.

Hereinafter, the coating corrosion prevention method of the steel structure of this invention is demonstrated in detail based on preferable embodiment of the coating corrosion prevention structure of the steel structure of this invention shown in FIG.1 and FIG.2.
The embodiment shown in FIGS. 1 and 2 is an example of the case where the coated anticorrosion method of the present invention is applied to a steel sheet pile as an anticorrosive body, and an anticorrosion layer disposed on the surface of the anticorrosive body (steel sheet pile) 4. 3 and a protective cover 1 mounted on the anticorrosion layer 3. The anticorrosion layer 3 has a two-layer structure composed of an inner layer 31 on the protective cover 1 side and a surface layer 32 on the surface side of the anticorrosive body 4.
Further, between the inner layer 31 of the anticorrosive layer 3 and the protective cover 1, a continuous foamed resin-based foam layer 2 is disposed.
FIG. 1 is a cross-sectional view showing a state after the anticorrosion layer 3 has expanded by water absorption, and FIG. 2 is a cross-sectional view showing a state before the anticorrosion layer 3 has expanded by water absorption.
In FIGS. 1 and 2, 5 is a belt-like base plate fixed to the connecting portion of the body 4 to be protected, 6 is a stat bolt fixed perpendicularly to the base plate 5, and 7 is a nut fitted to the stat bolt. The protective anticorrosion structure of the present embodiment includes a protective cover 1, a resin foam layer 2 and an anticorrosive layer 3 fitted into a stat bolt 6 through holes formed at one end thereof, and a nut 7. By being fixed, it is attached to the body 4 to be protected.

In this embodiment, first, the belt-like base plate 5 to which the stat bolt 6 is fixed in advance vertically by welding is fixed to the connecting portion of the corrosion-protected body 4 by welding. A plurality of the stat bolts 6 are attached to predetermined portions of the belt-like base plate 5 at predetermined intervals.
The protective cover 1, the resin foam layer 2, and the anticorrosion layer 3 are fitted into the stat bolt 6 through holes formed at one end thereof.

  The protective cover 1, the resin-based foam layer 2 and the anticorrosive layer 3 are made of synthetic rubber on the back surface of the protective cover 1 at the factory in advance from the viewpoint of simplifying the field work and shortening the working time. The above-described stat bolt 6 and nut 7 are fixed on the resin foam layer 2 and the anticorrosion layer 3 is attached to the resin foam layer 2 in this order by attaching the inner layer 31 and the surface layer 32 in this order. It is preferable to attach to the to-be-corroded body 4 with the fixing tool which consists of.

The anticorrosion layer 3 is a two-layer anticorrosion layer formed from a cured layer of a paste-like urethane resin having different water-absorbing polymer content, and the inner layer 31 contains more water-absorbing polymer than the surface layer 32. It is formed from a cured layer of paste-like urethane resin.
The surface layer 32 is preferably formed from a cured layer of a paste-like urethane resin having a water-absorbing polymer content of 0 to 10% by mass, particularly 1 to 7% by mass. It is preferably formed from a cured layer of a paste-like urethane resin having a content of 5 to 40% by mass, particularly 10 to 30% by mass.
If the content of the water-absorbing polymer in the inner layer 31 is small, the expansion rate becomes slow or the expansion becomes insufficient. If the content is too large, the expanded anticorrosion layer may become brittle and partially lost.
The surface layer 32 prevents the formation of gaps due to wrinkles in the portion to be protected 4 when the inner layer 31 absorbs and expands due to water absorption. For that purpose, the surface layer 32 contains a water absorbing polymer. The amount needs to be smaller than the content of the water-absorbing polymer in the inner layer 31.

The water-absorbing polymer may be any polymer having water-swellability, and examples thereof include acrylic acid-based polymers, isobutylene / maleic acid-based polymers, and polyvinyl alcohol-based polymers. Commercially available products can be used for these water-absorbing polymers. For example, as the acrylic polymer, trade name “AQUALIC CS-6S” manufactured by Nippon Shokubai Co., Ltd., product manufactured by Sumitomo Seika Co., Ltd. There are names such as "Aqua Keep".
The water-absorbing polymer preferably has an expansion coefficient measured by the following method in the range of 10 to 40 times, and more preferably in the range of 20 to 30 times.

[Measurement method of expansion coefficient]
The sample water absorption weight ratio after the sample is immersed in 3.5% saline for 2 hours is measured.

The urethane-based resin containing the water-absorbing polymer is paste-like, preferably a one-component moisture-curable water-expandable urethane-based resin, and a two-component curable urethane-based resin can also be used. As the one-component moisture-curable water-swellable urethane resin, for example, a polyurethane sealant mainly composed of an isocyanate group-containing prepolymer obtained by reacting a polyisocyanate and a polyether polyol can be used. Moreover, as a trade name of the one-component moisture-curing type water-expandable urethane-based resin, there are “Aqua Guard” and “Leak Master” manufactured by CI Kasei Co., Ltd.
In the case of using a urethane-based resin having no water-swelling property or a urethane-based resin having a low water-swelling property as the urethane-based resin, it is preferable to mix a little water-absorbing polymer.
Since the urethane-based resin is in the form of a paste, it is easy to mix a water-absorbing polymer, has rubber elasticity after curing, and preferably has an elongation of 600 to 1400% when forming the anticorrosion layer.

In the anticorrosion layer 3, the thickness of the inner layer 31 and the surface layer 32 is not unambiguous depending on the type of the urethane resin or the water-absorbing polymer, but the thickness of the inner layer 31 is preferably 2 to 15 mm. Preferably it is 2-5 mm, and the thickness of the surface layer 32 becomes like this. Preferably it is 0.5-3 mm, More preferably, it is 1-2 mm.
If the anticorrosion layer 3 becomes too thick, it will take time to follow the deformed portion of the object 4 to be protected, which causes an increase in cost and a decrease in work efficiency, which is not preferable.
In addition, a rust preventive agent can also be mix | blended with the inner layer 31 and the surface layer 32 of the anticorrosion layer 3. FIG.

  The protective cover 1 is preferably a glass fiber reinforced plastic (FRP) protective cover, and other protective covers made of plastic such as polyester resin, epoxy resin, polypropylene resin, and vinyl chloride resin, and corrosion resistant metals such as stainless steel and titanium. A protective cover consisting of can also be used.

The continuous foamed resin-based foam layer 2 disposed between the inner layer 31 of the anticorrosion layer 3 and the protective cover 1 is preferably water-absorbing and flexible, and is a sheet-like foam such as foamed polyethylene or foamed polyurethane. A material is used.
By disposing the resin foam layer 2 between the inner layer 31 of the anticorrosion layer 3 and the protective cover 1, the anticorrosion layer 3 mainly efficiently expands from the inner layer 31 due to moisture absorbed from the resin foam layer 2, It is possible to cover the object to be protected 4 having a complicated structure without any gaps, and it is possible to obtain a better state of covering and corrosion protection.

  In the present embodiment, when the protective cover 1, the resin foam layer 2, and the anticorrosive layer 3 are attached to the anticorrosive body 4, the anticorrosive layer 3 has an appropriate hardness, and therefore, as shown in FIG. There is a gap between the surface and the surface of the object 4 to be protected, but after the attachment, the anticorrosion layer 3 is filled with water and moisture existing inside the protective cover 1, and the anticorrosion layer 3 fills up. Thus, the gap is eliminated, and a good anticorrosive state as shown in FIG. 1 is obtained.

The present invention is not limited to the embodiment shown in FIG. 1 and FIG. 2 described above, and needless to say, various modifications can be made as appropriate without departing from the effects of the present invention.
Although not shown in FIGS. 1 and 2, in the present invention, the upper and lower ends of the protective cover are sealed with epoxy resin (for example, the upper and lower ends of the protective cover are water-stopped using an underwater curing type epoxy putty). It is preferable to have a structure. At the time of sealing, water and moisture remain inside the protective cover. When the anticorrosion layer 3 absorbs this water and moisture and expands, there is no gap and a good anticorrosion state as shown in FIG. 1 is obtained.
The present invention is preferably applied to a steel structure such as a steel sheet pile exposed to the marine environment.

Test examples 1 to 10 (evaluation test of the thickness of the anticorrosion layer)
An inner layer was prepared as shown in 1 below, and then a surface layer was prepared as shown in 2 below on the inner layer, and an anticorrosion layer composed of the inner layer and the surface layer having the thickness shown in Table 1 was prepared. .
1. Preparation of inner layer One-component moisture-curing water-expandable urethane resin (trade name “CI Aquaguard SS-10” manufactured by CI Kasei Co., Ltd.) and salt-resistant water-absorbing polymer (trade name “AQUA” manufactured by Nippon Shokubai Co., Ltd.) Rick CS-6S ”)) 20% by mass and applied onto an FRP plate (70 mm × 15 mm × 2.5 mm thickness), and the inner layer having a size of 70 mm × 15 mm and the thickness shown in Table 1 is applied to the FRP plate. Each was produced above. These inner layers were cured at room temperature for 1 day.
2. Preparation of surface layer On the inner layer, a one-component moisture-curable water-expandable urethane-based resin (trade name “Sea Aqua Guard SS-10” manufactured by CI Kasei Co., Ltd.) is applied, and the size is 70 mm × 15 mm. A surface layer having a thickness shown in FIG.
After preparation of the surface layer, the obtained anticorrosion layer was cured at room temperature for 7 days.
The surface state of each obtained anticorrosion layer was observed, and the ratio of the area of wrinkles and the followability of the steel sheet pile corners were examined by the following method.
(1) Percentage of wrinkle area After each of the obtained anticorrosion layers was immersed in natural seawater (off Hachijojima) at 20 ° C, it was taken out after 4 days and the wrinkle area relative to the total area of the anticorrosion layer surface (surface layer side) The ratio was calculated.
(2) Conformity of the uneven part On the transparent acrylic plate, a transparent acrylic bar having an isosceles triangular section with a 5 × 5 mm cross section, a height of 3 mm, and a base of 5 mm is attached with an adhesive to the uneven part. Was simulated. Subsequently, after installing each obtained anticorrosion layer in this uneven | corrugated | grooved part, the contact | adherence state of the uneven | corrugated | grooved part was confirmed visually after 7 days. Those with close contact regardless of the presence or absence of wrinkles were judged as “◎” (excellent), and those with large gaps were judged as “◯” (good).
And each anticorrosion layer was comprehensively evaluated from the said evaluation test result.
(3) Comprehensive evaluation Comprehensive evaluation is performed in three stages. Wrinkle area ratio is 0% and unevenness followability evaluation is "◎" (excellent), wrinkle area ratio is 1-9% Alternatively, “◯” (good) indicates that the follow-up evaluation of the unevenness is “good”, and “x” (defective) indicates a wrinkle area ratio of 10% or more.
The evaluation test results and comprehensive evaluation are shown in Table 1.

  As can be seen from the results of Test Examples 1 to 10, when the anticorrosion layer has a single layer structure having no surface layer, many wrinkles are generated, whereas the anticorrosion layer having a surface layer and an inner layer has a wrinkle generation. In particular, in the anticorrosion layer having a two-layer structure having a surface layer with a thickness of 1 mm or more, the anticorrosion layer was uniformly expanded without wrinkles. In Test Examples 8 to 10, the thickness of the surface layer was 5 mm or the thickness of the inner layer was 10 mm, and each anticorrosion layer was thick.

Test Example 11 (Evaluation test for water absorption expansion of the anticorrosion layer)
An inner layer is produced as in the following 1, and then a surface layer is produced on the inner layer as in the following 2, and an anticorrosive layer having a thickness of 8 mm (the thickness of the inner layer is 6 mm, the thickness of the surface layer is 2 mm). Produced.
1. Preparation of inner layer One-component moisture-curing water-expandable urethane resin (trade name “CI Aquaguard SS-10” manufactured by CI Kasei Co., Ltd.) and salt-resistant water-absorbing polymer (trade name “AQUA” manufactured by Nippon Shokubai Co., Ltd.) Lick CS-6S ") 20% by mass was mixed to prepare an inner layer having a diameter of 30 mm and a thickness of 6 mm. This inner layer was cured at room temperature for 1 day.
2. Preparation of surface layer On the inner layer, a one-component moisture-curing water-expandable urethane-based resin (trade name “Sea Aqua Guard SS-10” manufactured by CI Kasei Co., Ltd.) is applied, and the surface layer is 30 mm in diameter and 2 mm in thickness. Was made on the inner layer.
After preparation of the surface layer, the obtained anticorrosion layer was cured at room temperature for 7 days.
The obtained anticorrosion layer was immersed in natural seawater (off Hachijojima) at 20 ° C. and then arbitrarily taken out, and the mass, diameter, and thickness of the anticorrosion layer were measured. The results are shown in FIG. 3 (mass), FIG. 4 (diameter) and FIG. 5 (thickness), respectively.

Test Example 12 (Evaluation test for water-absorbability of the anticorrosion layer)
A foamed polyethylene having a diameter of 30 mm and a thickness of 5 mm (continuous foaming, expansion ratio of 15 times) was produced. On this foamed polyethylene, an inner layer and a surface layer were produced in the same manner as in Test Example 11, and an anticorrosion layer having a resin-based foam layer was obtained.
About the obtained anticorrosion layer, it carried out similarly to Test Example 11, and measured mass, a diameter, and thickness, respectively. The results are shown in FIG. 3 (mass), FIG. 4 (diameter) and FIG. 5 (thickness), respectively.

Test Example 13 (Evaluation test for water-swellability of the anticorrosion layer)
In Test Example 11, a single-layer structure anticorrosion layer having a thickness of 8 mm was obtained in the same manner as in Test Example 11 except that the thickness of the inner layer was 8 mm and no surface layer was produced.
About the obtained anticorrosion layer, it carried out similarly to Test Example 11, and measured mass, a diameter, and thickness, respectively. The results are shown in FIG. 3 (mass), FIG. 4 (diameter) and FIG. 5 (thickness), respectively.

3, 4, and 5, the graphs indicated by ◯ plots show the results of Test Example 11 (two-layer structure anticorrosion layer, no resin-based foam layer), and the graphs indicated by ◇ plots show Test Example 12 ( The result of the anti-corrosion layer having a two-layer structure and the resin-based foam layer is shown, and the graph indicated by the plot of ● indicates the result of Test Example 13 (corrosion-proof layer having a one-layer structure).
As can be seen from the results of Test Examples 11, 12, and 13, in the anti-corrosion layer having the two-layer structure of Test Examples 11 and 12, mild expansion was confirmed, whereas the one-layer structure having no surface layer of Test Example 13 was confirmed. It was confirmed that the anticorrosion layer expanded rapidly. Moreover, in the anticorrosion layer of the 1-layer structure without the surface layer of Test Example 13, many wrinkles were observed on the surface of the anticorrosion layer, and the shrinkage and water separation of the anticorrosion layer were confirmed after 6 days of immersion in seawater.

Test Example 14 (Consideration of content of water-absorbing polymer in inner layer and surface layer of anticorrosion layer)
An inner layer was produced as in the following 1, and then a surface layer was produced on the inner layer as in the following 2 to produce an anticorrosion layer having a two-layer structure of 70 mm × 15 mm × thickness 6 mm.
1. Preparation of inner layer One-component moisture-curing water-expandable urethane resin (trade name “CI Aquaguard SS-10” manufactured by CI Kasei Co., Ltd.) and salt-resistant water-absorbing polymer (trade name “AQUA” manufactured by Nippon Shokubai Co., Ltd.) Lick CS-6S ") 20 mass% was mixed and applied onto an FRP plate (70 mm x 15 mm x thickness 2.5 mm), and an inner layer of 70 mm x 15 mm x thickness 4 mm was produced on the FRP plate. This inner layer was cured at room temperature for 1 day.
2. Preparation of surface layer On the inner layer, a one-component moisture-curing water-expandable urethane-based resin (trade name “CI Aquaguard SS-10” manufactured by CI Kasei Co., Ltd.) and salt-resistant water-absorbing polymer (Nippon Shokubai Co., Ltd.) (Product name “Aquaric CS-6S”) mixed with 5% by mass was applied to form a surface layer of 70 mm × 15 mm × 2 mm in thickness on the inner layer.
After preparation of the surface layer, the obtained anticorrosion layer was cured at room temperature for 7 days.
The obtained anticorrosion layer was immersed in natural seawater (off Hachijojima) at 20 ° C. and then taken out after 4 days, and the ratio of the wrinkle area to the total area of the anticorrosion layer surface (surface layer side) was determined. The results are shown in Table 2.

Test Example 15 (Consideration of content of water-absorbing polymer in inner layer and surface layer of anticorrosion layer)
An inner layer was produced as in the following 1, and then a surface layer was produced on the inner layer as in the following 2 to produce an anticorrosion layer having a two-layer structure of 70 mm × 15 mm × thickness 6 mm.
1. Preparation of inner layer One-component moisture-curing water-expandable urethane resin (trade name “CI Aquaguard SS-10” manufactured by CI Kasei Co., Ltd.) and salt-resistant water-absorbing polymer (trade name “AQUA” manufactured by Nippon Shokubai Co., Ltd.) Rick CS-6S ”)) 5 mass% was mixed and applied on an FRP plate (70 mm × 15 mm × thickness 2.5 mm), and an inner layer of 70 mm × 15 mm × thickness 4 mm was produced on the FRP plate. This inner layer was cured at room temperature for 1 day.
2. Preparation of surface layer On the inner layer, a one-component moisture-curing water-expandable urethane-based resin (trade name “CI Aquaguard SS-10” manufactured by CI Kasei Co., Ltd.) and salt-resistant water-absorbing polymer (Nippon Shokubai Co., Ltd.) A mixture of 20% by mass (trade name “AQUALIC CS-6S”) was applied, and a surface layer of 70 mm × 15 mm × 2 mm in thickness was produced on the inner layer.
After preparation of the surface layer, the obtained anticorrosion layer was cured at room temperature for 7 days.
The obtained anticorrosion layer was immersed in natural seawater (off Hachijojima) at 20 ° C. and then taken out after 4 days, and the ratio of the wrinkle area to the total area of the anticorrosion layer surface (surface layer side) was determined. The results are shown in Table 2.

DESCRIPTION OF SYMBOLS 1 Protective cover 2 Continuous foaming resin-type foam layer 3 Anticorrosion layer 31 Inner layer 32 Surface layer 4 Corrosion-protected body (steel sheet pile)
5 Base plate 6 Stud bolt 7 Nut and washer

Claims (8)

  In a corrosion prevention method for a steel structure in which an anticorrosion layer is provided on the surface of an object to be protected and a protective cover is attached on the anticorrosion layer, the anticorrosion layer is made of a paste-like urethane system having different water-absorbing polymer contents. A two-layer structure composed of an inner layer and a surface layer composed of a cured layer of resin, wherein the inner layer is a corrosion-resistant layer containing more water-absorbing polymer than the surface layer, and the two-layered corrosion-proof layer is the protective cover. A method for coating corrosion protection of a steel structure, characterized in that it is integrally attached to a body to be protected.   The method for coating corrosion prevention of a steel structure according to claim 1, wherein a continuous foamed resin foam layer is disposed between the inner layer of the anticorrosion layer and the protective cover.   The water-absorbing polymer content of the surface layer of the anticorrosion layer is 0 to 10% by mass, and the water-absorbing polymer content of the inner layer of the anticorrosion layer is 10 to 30% by mass. A method for coating corrosion prevention of the steel structure as described.   The method for coating and preventing corrosion of a steel structure according to any one of claims 1 to 3, wherein an epoxy resin-based seal is applied to the upper and lower ends of the protective cover.   The steel according to any one of claims 1 to 4, wherein the water-absorbing polymer comprises at least one polymer selected from an acrylic acid polymer, an isobutylene / maleic acid polymer, and a polyvinyl alcohol polymer. Method of coating and anticorrosion of structures.   The steel structure according to any one of claims 1 to 5, wherein the hardened layer of the paste-like urethane resin that forms the anticorrosive layer is a hardened layer of a paste-like one-component moisture-curable water-expandable urethane-based resin. Coating anticorrosion method.   In a coated anticorrosion structure of a steel structure comprising an anticorrosion layer disposed on the surface of an anticorrosive body and a protective cover attached on the anticorrosion layer, the anticorrosion layer has a water-absorbing polymer content. A two-layer structure composed of a hardened layer of different pasty urethane resin and a surface layer, wherein the inner layer contains more water-absorbing polymer than the surface layer. Covered anti-corrosion structure.   The coated anticorrosive structure for a steel structure according to claim 7, wherein a continuous foamed resin-based foam layer is disposed between the inner layer of the anticorrosive layer and the protective cover.

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