JPS6172127A - Corrosionproof covered steel sheet pile - Google Patents

Abstract

PURPOSE:To enable improvement of corrosionproof properties and durability, by a method wherein a covering layer, formed on a part of the one surface of a steel sheet pile through the medium of an adhesive layer, is of polyethylene of higher than a given density, and has a given thickness and a given relation between the density and the thickness. CONSTITUTION:A steel sheet pile has a body part 1, joint parts 3 formed at rise parts 2 at both sides, and is formed on its surface with a laminate sheet formed with a sheetform covering layer 6 and adhesive layer 7. The covering layer 6 is a sheet with a thickness of 0.5mm or more which is formed by polyethylene having density of 0.920g/cm<2>. The covering layer 6 is formed so that there is a given formula relation between the density of the polyethylene and the thickness of the covering layer. This enables provision of excellent resistance to heat and resistance to impact for the covering layer of polyethylene, and permits sharp reduction of moisture permeability of the covering layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to anti-corrosion coated steel sheet piles coated with polyethylene.

[Background of the invention] Conventionally, steel sheet piles for civil engineering and construction have been used for the purpose of revetment of rivers, coasts, ports, etc., or for construction purposes by continuously driving a large number of steel sheet piles into the ground to form a protective shelf. It is also used at dredging sites to secure the ground and prevent mixed paper from flowing into the work site or collapsing.

The steel sheet piles used in this way are constantly in contact with river water, drainage water, rainwater, seawater, etc. in the natural environment, are exposed to the atmosphere and sunlight, and are directly resistant to soil, mud, debris, etc. Corrosion is likely to occur due to contact, especially
Steel sheet piles are severely corroded in environments such as ports and estuaries where driftwood, waves, etc. interact alternately with the atmosphere and sunlight.

Despite this fact, steel sheet piles are often used without effective corrosion prevention measures. ,
Even if the steel sheet pile itself is made of highly corrosion-resistant steel, it is likely to be corroded due to being used in the natural environment mentioned above, and its service life will be relatively short, resulting in long-term use (e.g. , approximately 20 years or more).

[Prior art and its problems] On the other hand, as a method of preventing corrosion of steel sheet piles, there are methods of painting with paints with good anti-corrosion or weather resistance such as inorganic zinc paints and tar/epoxy resin paints, A method of forming the FRP coating layer using a synthetic resin such as an unsaturated polyester resin, or a method of forming an FRP coating layer using a synthetic resin mixed with a fibrous material has been proposed. However, since steel sheet piles are used in the harsh environments mentioned above, the corrosion prevention measures used for steel sheet piles must have excellent mechanical strength, long-term durability, and excellent corrosion resistance. Despite such requirements, costs tend to be kept low due to corrosion prevention.

Therefore, it is difficult to say that the above-mentioned anti-corrosion coating bundle can satisfy all of these conditions, and is not necessarily an appropriate method for coating steel sheet piles.

[Object of the Invention] The present invention provides an anti-corrosion coated steel sheet pile coated with an R-layer which exhibits good anti-corrosion properties and has extremely good durability, and which provides an anti-corrosion coated steel sheet pile in which such a coating layer can be formed economically. The purpose of the present invention is to provide a corrosion-resistant coated steel sheet pile.

[Summary of the Invention] The present invention provides an anti-corrosion coated steel sheet pile in which a coating I'1m is formed on at least a portion of one side of the steel sheet pile via a pleasing agent layer, and the coating layer has a density of 0.920 g / An anticorrosive coating, which is a coating layer with a thickness of 0.5 mm or more formed of polyethylene of c m' or more, and wherein the density of the polyethylene and the thickness of the coating layer have a relationship represented by the following formula: Provide steel sheet piles.

ρ ≧ 0.004L ” -0,031t +
0.87? [where ρ is the density of the polyethylene expressed in g/cm' and t is the thickness of the coating layer expressed in mm] [Detailed Description of the Invention] The density of the polyethylene (polyethylene resin) used to cover the steel sheet piles and the thickness of the coating layer made using this polyethylene are set as values within a specific range, and the values of both are expressed by the above relational expression. By setting it within this range, the water vapor permeability (water permeability) of the coating layer formed on the steel surface of the steel sheet pile is significantly reduced, thereby improving the anticorrosion effect.

The present invention will be described below with reference to one drawing.

Fig. 1 is a perspective view showing an example of a steel sheet pile, and Fig. 2 is a perspective view showing an example of a protective shelf formed by sequentially driving the steel sheet piles shown in Fig. 1 into the ground. It is a diagram.

The steel sheet piles used in the present invention are not particularly limited in shape and size, and any steel sheet piles that are commonly used for civil engineering, construction, etc. can be used.

As an example of the shape of the steel sheet pile, as shown in Fig. 1, it has a main body l with a roughly U-shaped cross section, and the rising parts (sometimes called flanges) 2 on both sides have small inner diameters. Including long steel plate structural members having a joint part 3 bent outward to form a cylindrical shape, those whose cross-sectional shape is straight, Z-shaped, and S-shaped. You can mention things like.

Further, as an example of a steel sheet pile having a roughly U-shaped cross-sectional structure, it is formed of a steel plate with a thickness of 5 to 30 InIn, particularly 7.5 to 28 mm, and a width of about 200 to 800 InIn.
mm, especially 300-600 mm, the height of the rising part on both sides is about 50-300 mm, especially 70-250 mm, and the length is about 2-30 m, especially 5-20 m. can.

Usually, as shown in FIG. 2, a large number of steel sheet piles 4 are connected by joints 3 on both sides, and the steel sheet piles are sequentially driven into the ground to form a protective shelf 5.

The anti-corrosion coated steel sheet pile of the present invention has a coating layer attached to a part of at least one side of the steel sheet pile.Since the anti-corrosion coated steel sheet pile of the present invention is used for the above-mentioned protective shelves, it is suitable for use in protective equipment. It is preferable that an R-covered layer is attached to the surface of the steel sheet pile that is hit by seawater or river water when constructing the steel sheet pile.

Note that the steel sheet pile used in the present invention may have its surface treated for anticorrosion in advance to improve its anticorrosion performance. Alternatively, it is preferable to remove mill scale, red rust, dirt, etc. from the surface by pre-treatment such as pickling.Furthermore, the surface of the steel sheet pile is treated with chromic acid or phosphoric acid, or further coated with an epoxy resin primer. By doing so, the adhesion of the WI layer can be further improved.

The coating layer of the anti-corrosion coated steel sheet pile of the present invention is attached to the steel sheet pile via an adhesive layer. The adhesive layer not only attaches the steel sheet pile to the coating layer for 1m, but also adheres to the surface of the steel sheet pile to protect the steel sheet surface.Also, even if a minute amount of moisture passes through the coating layer, this adhesive layer will protect the steel sheet pile. It may also have the effect of preventing moisture from reaching the steel surface.

There are no particular restrictions on such adhesives, but the bonding temperature is approximately 5
It is preferable to use a heat-adhesive (hot-melt type) adhesive that has a temperature within the range of 0 to 250°C, preferably 80 to 220°C, and further has adhesive strength (90 degree peeling, tensile speed) to the steel plate surface. 50mm/min, 20℃) is approximately 2
kg/cm or more, preferably 4-20 kg/c
It is preferable that the adhesive be of the order of m and has appropriate flexibility even after adhesion.

Preferred examples of the adhesive of the present invention include compositions containing maleated modified polyethylene as a main component, and compositions containing olefin homopolymers or copolymers of 30 to 30%.
An adhesive composition containing 80% by weight, 30 to 50% by weight of a (block) combination of an aromatic hydrocarbon having a vinyl group and a conjugated diene compound, and 40 to 15% by weight of an adhesive agent 1j. etc. can also be mentioned.

Examples of olefin homopolymers or copolymers used in the above adhesives include polyethylene/, polypropylene, polyvinyl chloride, and modified polymers thereof (e.g., maleated polyethylene, maleated polypropylene, etc.), Ethylene/vinyl acetate copolymers, copolymers of (meth)acrylic acid esters (esters with lower alkyl such as methyl, ethyl, propyl, butyl) and ethylene, and copolymers of (meth)acrylic acid and ethylene. These can be used alone or as a mixture of two or more types. In addition, examples of (block) copolymers of aromatic hydrocarbons having vinyl groups and conjugated diene compounds include styrene, butadiene,
Examples include styrene (block) copolymer, styrene/isoprene/styrene (block) copolymer, and the like.

The adhesive material 7j to be added to the above adhesive is as follows.

Any tackifier can be selected from commonly used tackifiers in known adhesive compositions. Examples of tackifiers include rosin and rosin derivatives (e.g., glycerin esters of hydrogenated rosin),
Pinene-based resins (e.g., oligomers of β-pinene, pinene-based resins obtained from β-pinene and phenolic compounds, etc.)
, hydrocarbon resin [e.g., aliphatic hydrocarbon resin (Cs fraction,
pentene, isoprene, 1,3-pentadiene, etc.), aromatic hydrocarbon resins (Cs fraction,
(styrenes, indenes, etc. alone or copolymers),
Alicyclic hydrocarbon resins], fucron resins, coumaron/indene resins, other polymeric substances (eg, phenolic resins, alkylphenol resins, naphthenic oils, modified thenebenes, etc.), and oily substances.

In addition to the above-mentioned ingredients, the adhesive also contains talc, calcium carbonate,
Inorganic fillers such as silica (silicon dioxide), alumina, mica, and carbon black, or additives such as antioxidants, corrosion inhibitors, colorants, and softeners may be further blended.

Examples of corrosion inhibitors that can be incorporated into adhesives as additives include inorganic corrosion inhibitors (e.g., metal chromates, metal phosphates, metal sulfites, metal borates, molybdenum #salts, nitrite metal salts, etc.) and organic corrosion inhibitors (e.g. metal salts of aromatic carboxylic acids, aliphatic or aromatic compounds with multiple hydroxyl groups, organic acids such as tannic acid, etc.) be able to.

In the anti-corrosion coated steel sheet pile of the present invention, a coating layer is formed on at least a part of one side of the steel sheet pile via the adhesive layer as described above. is preferably formed, where 1 is approximately the entire area j
means the surface area where the steel sheet pile comes into contact with a corrosive atmosphere such as seawater.

The coating layer formed on the anti-corrosion coated steel sheet pile of the present invention has a density of 0.920 g/Crr? A polyethylene coating layer formed from the above polyethylene.

It is necessary that the thickness of the coating layer is 0.5 mm or more.

The density of polyethylene is 0,920 g/cm
``There is no particular restriction on the upper limit of the density as long as the other relationships of the present invention are satisfied, but usually the upper limit is 0.
．． It is about 970g/cm''.

The polyethylene used is not simply limited to polyethylene homopolymers, but includes, for example, copolymers of ethylene with other olefins such as propylene, copolymers of ethylene with other monomers such as vinyl acetate, Alternatively, homopolymers or copolymers thereof may be modified with, for example, dicarboxylic acids or their anhydrides, particularly maleic acid or maleic anhydride. Furthermore, there are no particular restrictions on the method for producing polyethylene itself, and known methods are known. Any polyethylene produced by a method (eg, high pressure method, medium pressure method, low pressure method, etc.) can be used.

In addition, in the present invention, when "polyethylene" is described without particular limitation, the above-mentioned materials are collectively referred to.

In addition, the polyethylene mentioned above also contains commonly used additives such as plasticizers, antioxidants, flame retardants, various colorants, and fillers (e.g., calcium carbonate, silica, carbon black, etc.). It may be blended.

However, in the present invention, the density of polyethylene refers to the density of polyethylene that does not contain the above-mentioned additives.

The thickness of the coating layer formed using polyethylene as described above needs to be 0.5 mm or more. The thickness of the formed coating layer is 0.5 mm or more, and as long as the other relationships of the present invention are satisfied, there is no particular restriction on the upper limit, and the thickness may be, for example, about 10 mm. Considering productivity etc., it is generally 4 mm or less, and usually 3 mm.
．． 5 mm or less, and a particularly preferable range is 2.5 mm.
It is as follows.

In addition, there is no particular restriction on the thickness of the coating layer and the adhesive layer, but
Covered! The ratio of layer thickness to adhesive layer thickness is 20:l-1
The total thickness of the coating layer and the adhesive layer is preferably in the range of :l, particularly preferably in the range of 20:1 to 4:1.

Generally, it is about 0.6 to 5.5 mm, and usually 0.6 to 5.5 mm.
A material with a diameter of about 7 to 3.5 mm is used.

The coating layer formed depends on the density of the polyethylene used,
It is necessary that the thickness of the formed coating layer has the following relationship.

ρ≧0.004t ” -0,031t 10.977
[p and t have the same meanings as above] FIG. 3 shows the relationship between the density of polyethylene, the thickness of the coating layer, and the above formula.

That is, for the coating layer of the present invention, it is necessary that the density of the polyethylene used and the thickness of the coating layer formed fall within the shaded area in FIG. Further, FIG. 3 also shows preferred ranges in relation to the above-mentioned density of polyethylene, the thickness of the coating layer, and the above-mentioned formula. That is, the region indicated by "I" in FIG. 3 reduces the range in which the coating layer of the present invention exhibits particularly preferable properties as an anticorrosion coating layer, and the region indicated by rI[J indicates the preferable range of properties. It shows. Due to the above relationship between the density of polyethylene and the thickness of the coating layer, the moisture permeability (water permeability) of the coating layer is extremely low. Very little moisture reaches the steel surface, demonstrating extremely good corrosion resistance.

Density of polyethylene is 0,920 g/cm'
In order to satisfy the above relationship, if lower than
It is necessary to make the thickness of the coating layer considerably thick, which is disadvantageous in terms of manufacturing technology and economy.

On the other hand, if the thickness of the coating layer is 0.5 mm or less, in order to satisfy the above relationship, it is theoretically possible to use polyethylene with a very high density. The density of currently manufactured polyethylene resins has a limit and is not practical in reality.The highest density of polyethylene that can currently be manufactured industrially is 0.970g/
It is about am'.

There are no particular restrictions on the method of covering steel sheet piles with polyethylene, and any known method can be used.

FIG. 4 is a sectional view showing the process of attaching a laminated sheet (a covering sheet with an adhesive layer attached) to the recessed portion of the steel sheet pile shown in FIG. 1.

5 and 6 are cross-sectional views of the anti-corrosion coated steel sheet pile of the present invention, which is obtained by applying anti-corrosion coating to the steel sheet pile of FIG. 1.

As an example of the method for manufacturing the anticorrosive coated steel sheet pile of the present invention, as shown in FIG. 8
A one-layer sheet 8 is arranged so that the adhesive layer of this laminated sheet and the surface of the steel sheet pile face each other, and a pressing force is applied from the outside along the surface of the steel sheet pile while heating this laminated sheet 5. As shown in FIG. 5, a sheet-like coating layer 6 is applied.
An example of a method is to adhere a laminated sheet 8 consisting of a and an adhesive layer 7 to the surface of a steel sheet pile to form a corrosion protection wave WI layer.

Another method is to extrude polyethylene from an extrusion molding machine at an extrusion temperature that is above the melting point of the polyethylene used and up to the melting point plus 150°C to form sheets, cylinders, or other shapes. A method of forming a molded article by continuously extruding it into the shape of . Then, while the molded body is heated and softened, it is closely attached along the surface of a steel sheet pile provided with an adhesive layer, which is also continuously supplied, to form a coating layer as the outermost layer on the surface of the steel sheet pile. It is also possible to use a method of forming an anti-corrosion coating layer.

In addition, as shown in FIG. 6, the same operation is performed on one convex side of the roughly mouth-shaped steel sheet pile, and a laminated sheet consisting of a sheet-like coating layer 6 and an adhesive layer 7 is applied to the steel surface. Attached to the anti-corrosion wave 'lf! layers can be formed.

The coating layer may be attached to a part of one side of the steel sheet pile, but when coating a recessed part of the steel sheet pile as shown in FIG. 3, and when coating one convex side of a steel sheet pile, it is usually carried out from the main body part 1 to the rising part 2.

Immediately after the coating layer has been formed by adhering the coating layer to the surface of the steel sheet pile under heating, the steel sheet pile is then cooled to near room temperature in a relatively short period of time by air cooling, water cooling, or other known cooling methods. Cooling is preferred.

[Effect of the invention] The anti-corrosion coated steel sheet pile of the present invention exhibits good anti-corrosion properties because it is coated with a coating layer that has extremely good durability.
And the anti-corrosion wave rfI layer can be formed economically.

In other words, the anti-corrosion coated steel sheet pile of the present invention has excellent heat resistance and impact resistance because the outermost polyethylene coating layer has excellent heat resistance and impact resistance. Steel sheet piles can be coated and protected from impact caused by strong contact with underground stones, gravel, gravel, etc., and from +a and erosive forces caused by river water, sea water, and drifting objects.

Further, as described above, by using polyethylene of a specific density to form a YD layer of a specific thickness and having the above-mentioned relationship between the degree and the thickness, the layer to be protected can be can have very low moisture permeability. Therefore, the amount of moisture that passes through the coating layer and the adhesive layer and reaches the steel surface of the steel sheet pile is negligible, so the steel sheet pile can be used for a long period of time (for example, 20 years or more). It becomes possible to prevent corrosion.

Furthermore, although the anti-corrosion coated steel sheet pile of the present invention has excellent anti-corrosion properties as described above, it is relatively easy to use! i!
This makes it possible to reduce the cost required for corrosion protection.

Next, Examples and Comparative Examples of the present invention will be shown.

The moisture permeability measurements, peel strength tests, impact strength tests, and salt water resistance durability tests measured in the following Examples and Comparative Examples were conducted as follows.

The test was carried out on a laminated sheet consisting of a polyethylene sheet and an adhesive layer in accordance with JIS-Z-0208.

1111 S1: A 90 degree peel test was conducted at 20° C. and a tensile speed of 50 mm/min.

1 circle i 5 kosu J@': Performed according to ASTM-G-14.

: The anti-corrosion coated steel sheet pile was immersed in 3.0 wt% saline solution at 60°C, and the time until rust appeared on the surface of the anti-corrosion coated steel sheet pile was measured.

[Example 1] Approx.
℃, and a polyethylene sheet containing 2.5% by weight of carbon black (density: 0
．． 943 g/Cm3, thickness: 2 Omm,) was coated with 0.5 mm thick maleated modified polyethylene adhesive (M8 from Malene et al., OX 10''%/g life PE,
? Density of L/inized polyethylene: 0.922g/
cm') was placed and heat-bonded to form a Fj layer to produce an anti-corrosion coated steel sheet pile.

The adhesive layer used in the Examples and Comparative Examples of the present invention is as described above. The impact strength of the flat section of this anti-corrosion coated steel sheet pile was 1.2 kg·m.

The thickness of this polyethylene sheet and adhesive layer is 2.5 mm.
The moisture permeability of a mm laminated sheet is 0.07g/m'・24
It was time.

Salt water resistance durability tests were conducted using the anti-corrosion coated steel sheet piles obtained as described above, but no rust was observed even after 12 months.

As a result of a peel test of the anticorrosion coating layer of the test piece of the salt water resistance durability test after the above m = months, the peel strength was approximately 15
kg/cm. The peel strength before the salt water resistance test was approximately 20 kg/cm.

A steel sheet pile with anti-corrosion coating on the concave portions and a steel sheet pile with the convex portions coated are manufactured using a method similar to the method described above. The layer was placed so that it was in contact with seawater, and a seawall was created for the coast.

The pouring method followed the usual method.

After six months had passed, this steel sheet pile was pulled out and observed.
A part of the part that was buried in the soil has a depth of 1
．． There were scratches of approximately 0 mm, but no scratches that reached the steel surface of the steel sheet pile were detected. Furthermore, no "bulges" due to rust formation were observed around the scratches.

There were no visible scratches on the coating layer on the part that had been immersed in seawater and the part above it that had been in contact with the atmosphere.

[Example 2] In Example 1, density 0, 952 g/cm
A corrosion-proof coated rtI-layer steel sheet pile was manufactured in the same manner as in Example 1, except that a polyethylene sheet with a thickness of 1.0 mm was used.

The thickness of this polyethylene sheet and adhesive layer is 1.5
The moisture permeability of mm Ja layer sheet is 0.09g/rn'02
It was 4 hours.

Using the obtained anti-corrosion coated steel sheet pile, the same good results as in Example 1 were obtained in the salt water resistance durability test and the anti-corrosion test on coastal seawalls, which were performed in the same manner as in Example 1.

[Example 3] In Example 1, the density was 0.943 g/cm'' and the thickness was 1
．． A corrosion-resistant coating layer steel sheet pile was manufactured in the same manner as in Example 1 except that a 5 mm polyethylene sheet was used.

The thickness of this polyethylene sheet and adhesive layer is 2.0
The moisture permeability of mm M layer sheet is 0.09g/rn'・24
It was time.

The obtained anti-corrosion coated steel sheet piles were operated in the same manner as in Example 1, and the same good results as in Example 1 were obtained in the salt water resistance durability test and the corrosion resistance test on seawalls.

[Example 4] In Example 1, the density was o, 935 g/c♂, and the thickness was 2.
A corrosion-resistant coating layer steel sheet pile was manufactured in the same manner as in Example 1, except that a 0 mm polyethylene sheet was used.

The thickness of this polyethylene sheet and adhesive layer is 2.5 mm.
The moisture permeability of the mm laminated sheet was 0.10 g/m' for 24 hours.

The obtained anti-corrosion coated steel sheet piles were operated in the same manner as in Example 1, and the same good results as in Example 1 were obtained in the salt water resistance durability test and the corrosion resistance test on seawalls.

[Example 5] In Example 1, the density was 0.952 g/am'' and the thickness was 2.
．． A corrosion-resistant coating layer steel sheet pile was manufactured in the same manner as in Example 1 except that a 5 mm polyethylene sheet was used.

The thickness of this polyethylene sheet and adhesive layer is 3.0
The moisture permeability of the mm laminated sheet is 0.05g/rn'-24
Ivy due to time.

The obtained anti-corrosion coated steel sheet piles were operated in the same manner as in Example 1, and the same good results as in Example 1 were obtained in the salt water resistance durability test and the corrosion resistance test on seawalls.

[Example 6] In Example 1, except that a polyethylene sheet with a density of 0.943 g/c+n' and a thickness of 2.5 mm was used,
An 11-layer steel sheet pile with anti-corrosion coating was manufactured in the same manner as in Example 1.

The thickness of this polyethylene sheet and adhesive layer is 3.0
The moisture permeability of the mm laminated sheet is 0.06g/rn'-24
Time leaks.

The obtained anti-corrosion coated steel sheet piles were operated in the same manner as in Example 1, and the same good results as in Example 1 were obtained in the salt water resistance durability test and the corrosion resistance test on seawalls.

[Example 7] In Example 1, density 0, 935 g/cm
A steel sheet pile with an anti-corrosion coating was produced in the same manner as in Example 1, except that a polyethylene sheet with a thickness of 2.5 mm was used.

The thickness of this polyethylene sheet and adhesive layer is 3.0
The moisture permeability of a mm laminated sheet is 0.09g/11T'・2
It was 4 hours.

Using the obtained anti-corrosion coated steel sheet pile, salt water resistance durability test and coastal protection were conducted in the same manner as in Example 1) °I!
In the corrosion resistance test in Example 1, the same results were obtained.
It showed f results.

[Example 8] In Example 1, 15 degrees 0, 926 g/c
An anticorrosive coating layer steel sheet pile was manufactured in the same manner as in Example 1, except that a polyethylene sheet having a thickness of 2.5 mm was used.

The thickness of this polyethylene sheet and adhesive layer is 3.0
The moisture permeability of the mm A-layer sheet is 0. lLg/rry'・2
It was 4 hours.

The impact strength of the coating layer of this anti-corrosion coated steel sheet pile main body is 1.
It was 16 kg・m.

The obtained anti-corrosion coated steel sheet piles were operated in the same manner as in Example 1, and the same good results as in Example 1 were obtained in the salt water resistance durability test and the corrosion resistance test on seawalls.

[Comparative Example 1] In Example 1, density 0, 926 g/cm
A corrosion-resistant coating layer steel sheet pile was produced in the same manner as in Example 1, except that a polyethylene sheet with a thickness of 0.8 mm was used.

The thickness of this polyethylene sheet and adhesive layer is 1.3
The moisture permeability of the 81-layer sheet of mm is 0.34g/rr1'.
It was 24 hours.

Results of a salt water resistance test conducted using the obtained anti-corrosion coated steel sheet pile in the same manner as in Example 1.

After about 12 months, no rust was observed, but a significant decrease in peel strength was observed. Furthermore, in a corrosion protection test on a coastal revetment conducted in the same manner as in the example, scratches that reached the steel surface of the steel sheet pile were observed in some parts buried in earth and sand, and the surrounding area of these scratches The coating layer was "blistered" due to H. In addition, scratches were observed on parts that had been in contact with seawater.

[Comparative Example 2] In Example 1, density 0, 917 g/cm
A corrosion-resistant coating layer steel sheet pile was produced in the same manner as in Example 1, except that a polyethylene sheet with a thickness of 0.8 mm was used.

The thickness of this polyethylene sheet and adhesive layer is 1.3
The moisture permeability of the 24-hour planted layer sheet was 0.47 g/m''.

The impact strength of the coating layer of this anti-corrosion coated steel sheet pile main body is 1.
It was 2 kg-m.

Results of a salt water resistance test conducted using the obtained anti-corrosion coated steel sheet pile in the same manner as in Example 1.

After about 12 months, no rust was observed, but the peel strength of the coating layer on the main body of the anti-corrosion coated steel sheet pile was about 1.5K.
g/cm, which was significantly lower than the peel strength of about 14.0 kg/cm before the salt water durability test. Furthermore, in a corrosion protection test on a coastal revetment conducted in the same manner as in Example 1, scratches of 1 mm or more reaching the steel surface of the steel sheet pile were observed in some parts buried in the earth and sand. The coating layer around the scratch had ``bulged'' due to rust. In addition, scratches of about 0.5 mm were observed on the parts that had been in contact with seawater.

[Comparative Example 3] In Example 1, density 0, 917 g/cm
Example 3: An anticorrosion liquid m-layer steel sheet pile was manufactured in the same manner as in Example 1, except that a polyethylene sheet having a thickness of 1.2 mm was used.

The thickness of this polyethylene sheet and adhesive layer is 1.7
The moisture permeability of the 111-layer sheet of mm is 0.31g/m'・2
It was 4 hours.

As a result of a salt water resistance test conducted using the obtained anti-corrosion coated steel sheet pile in the same manner as in Example 1, after about 12 months,
Although no rust was observed, a significant decrease in peel strength was observed. moreover.

In a corrosion protection test on a coastal revetment conducted in the same manner as in the example, scratches that reached the steel surface of the steel sheet pile were observed in some parts buried in earth and sand, and the coating layer around these scratches was observed. ``Bulge'' was caused by M. In addition, scratches were observed on parts that had been in contact with seawater.

[Brief explanation of drawings]

Figure 51 is a perspective view showing a steel sheet pile having a roughly U-shaped cross section, which is an example of the steel sheet pile used in the present invention. FIG. 2 is a perspective view showing an example of a protective measure formed by continuously driving the steel sheet piles shown in FIG. 1 into the ground. FIG. 3 is a graph showing the relationship between the density of polyethylene and the thickness of the coating layer, and showing the preferable range of the coating layer defined in the present invention. FIG. 4 is a sectional view showing a state in which the concave portion of the steel sheet pile shown in FIG. 1 is coated. FIG. 5 is a sectional view of the anti-corrosion coated steel sheet pile in which a coating layer is formed in the concave portion of the steel sheet pile shown in FIG. 1. FIG. 6 is a sectional view of the anti-corrosion coated steel sheet pile in which a coating layer is formed on the convex surface of the steel sheet pile shown in FIG. 1. l: main body part, 2: rising part, 3: joint part. 4: steel sheet pile, 5: protective shelf, 6: coating layer, 7: adhesive layer,
゛8: Laminated sheet patent applicant Nippon Steel Corporation Ube Industries Co., Ltd. Representative Patent attorney Yasuo Yanagawa Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. An anti-corrosion coated steel sheet pile in which a coating layer is formed on at least a portion of one side of the steel sheet pile via an adhesive layer, wherein the coating layer has a density of 0.920 g/cm^3 or more. A coating layer with a thickness of 0.5 mm or more formed of polyethylene,
A corrosion-resistant coated steel sheet pile characterized in that the density of the polyethylene and the thickness of the coating layer have a relationship represented by the following formula: ρ≧0.004t^2−0.031t+0.977 [where ρ is g density of the polyethylene expressed in /cm^3 and t is the thickness of the coating layer expressed in mm]. 2. The above-mentioned coating layer is formed on almost the entire area of at least one side of the steel sheet pile via a heat-adhesive adhesive layer having an adhesive temperature in the range of 50 to 250°C. The anti-corrosion coated steel sheet pile according to item 1.