JPS6316538B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to heavy corrosion-resistant steel sheet piles with excellent durability. Prior Art and Problems In recent years, there has been an increasing demand for heavy-duty corrosion protection that enables long-term corrosion protection for various steel structures without repair.
This trend is no exception for the steel sheet piles that form the quay walls of ports, rivers, reclaimed land, etc., and thick film coatings are now being applied. There are types of steel sheet piles with various cross-sectional shapes, such as U-shapes, Z-shapes, and I-shapes, and all of them have fitting joints in the longitudinal direction. The steel sheet piles are driven while fitting these joints one after another to form a wall surface to form a structure such as a quay. Since the joints fit and connect in this way, if the joint part is coated too thickly, it will not be possible to fit them together. For this reason, there is a situation in which the coating applied to the steel sheet piles can only be applied to areas that do not come into contact with the joints of the mating steel sheet piles due to the fitting of the joints. However, since the contact portion is a portion that is hidden by fitting, there is little corrosion, and the purpose of corrosion prevention can be achieved to some extent by applying an anticorrosion coating to the other portions, that is, the portions exposed after fitting and connection. However, since such coatings have edges that are not hidden, there is a concern that corrosion under the coating or peeling of the coating may occur starting from these edges. To prevent this, a thin film such as coal tar epoxy paint is applied adjacent to the coated end so that the coated end is hidden inside the joint when mated. There is a risk that it will be easily damaged by abrasion during fitting and pouring. Although this damage is not a problem because it occurs in the concealed area, when considering long-term corrosion protection, there was a need for further improvement in the corrosion protection design near the fitting joint. Structure of the Invention The present inventors have attempted various improvements in view of the above situation, and as a result, have achieved the present invention. The gist of the present invention is that one side or both sides of a steel sheet pile,
A resin-based and/or mortar-based anti-corrosion coating is provided for the entire length or a portion of the longitudinal direction of the steel sheet piles at the parts that are exposed when the steel sheet piles are fitted and connected, and at least the above-mentioned anti-corrosion coating is provided for the parts that are hidden by the fitting. The heavy corrosion-resistant steel sheet pile has excellent durability and is characterized by having an aluminum or aluminum alloy thermal spray coating applied to the adjacent portion. The present invention will be explained in detail below. First, since steel sheet piles are generally connected by reversing the direction of each piece, in the present invention, one side refers to, for example, a U-shaped steel sheet pile 1 as shown in FIGS. 1 and 2. It means only a convex surface and only a concave surface, and "both sides" means both of these convex and concave surfaces. In the embodiments shown in FIGS. 1 and 2, the anticorrosion coating 2 is applied only to one side. These opposing materials are connected and used with the side on which the anticorrosive coating 2 is continuously formed facing, for example, the sea side. When heavy corrosion protection is required on the opposite side, an anticorrosion coating 2 is applied to both sides as shown in FIG. Although it is of course desirable that the anti-corrosion coating 2 be applied over the entire length of the steel sheet pile, it can also be applied to a portion of the steel sheet pile in the longitudinal direction, as shown in FIG. This is the case, for example, when anti-corrosion measures are taken only in the area from just below the water surface to the spray zone where corrosion is most severe in the ocean. Here, the resin-based and/or mortar-based anticorrosive coating used in the present invention refers to a cured product of epoxy, polyester, or phenol with a thickness of 0.2 mm or more, or a cured product of 1 mm or more, which can achieve long-term corrosion protection. This refers to cured urethane products, polyethylene, polypropylene, mixed cured products of mortar and resin, mortar with a thickness of 10 mm or more, and of course, modified products, mutual mixtures, mutual laminates, or various colors of these. Pigments, extender pigments, aggregates such as silica, glass flakes, mica, iron oxide,
Products with additives such as glass fiber and carbon black may also be included. Of course, a primer may be used before applying the coating, or a top coat may be applied after application. The various coatings described above can be applied to the surface of the steel sheet pile by various means such as spray painting, solventless two-component coating, powder coating, and pasting of formed sheets. In addition, the adjacent portion of the anti-corrosion coating 2 refers to the area from the end of the anti-corrosion coating 2 to the inside of the joint that is hidden by the fitting in the vicinity of the fitting portion. At least this portion is coated with an aluminum or aluminum alloy thermal spray coating 3. The reason for applying the aluminum or aluminum alloy thermal spray coating is to suppress corrosion under the coating and peeling of the coating from the edges of the anticorrosive coating. In other words, since the natural electrode potential in seawater is slightly less noble than the steel covered with aluminum or aluminum alloy, corrosion of the steel covered with the anti-corrosion coating is electrochemically suppressed, and peeling of the edges of the anti-corrosion coating is prevented. It also prevents These effects are more effective as the distance between the anti-corrosion coating and the thermally sprayed coating is smaller, and it is desirable that the two coatings be in contact with each other as much as possible during actual coating construction. In addition, an oxide film that is generally insoluble in seawater is formed on aluminum or aluminum alloy thermal spray coatings, which seals the pores in the thermal spray coating and eliminates rattling at the joints of steel sheet piles, which is not achieved with organic coatings. It is also effective in preventing corrosion of steel sheet pile claws, which cannot be protected against corrosion. Furthermore, when steel sheet piles are fitted together and placed, the aluminum or aluminum alloy thermal spray coating is sufficiently strong against scratches that occur at the fitting joints, and does not cause scratches like resin-based coatings. Less is. Even if scratches occur, the flame-sprayed coating is slightly less noble than the steel material, so there is no risk of pitting occurring as would occur if a resin coating were to develop. Here, the aluminum or aluminum alloy used in the present invention refers to pure aluminum of various purity levels, aluminum/zinc alloys of various ratios, etc., and is applied by means such as arc spraying, gas spraying, and plasma spraying. The thickness of the thermal spray coating is preferably 0.1 mm or more in terms of corrosion protection. On the other hand, in terms of suitability for fitting steel sheet piles, it is best to keep it at around 0.5mm. The thermal spray coating may be sealed with various resins by conventional means. The thermal spray coating 3 should be applied as necessary to all uncoated parts, such as the edges of the coating that occur when the anticorrosive coating 2 is partially applied in the longitudinal direction, or the back side when one side is coated, as shown in Figure 4. Can be done. Further, as described above, it is desirable that the anticorrosion coating 2 and the thermal spray coating 3 are placed in contact with each other, but this may be in either an abutting state or a partially overlapping state. FIG. 5 is a partially enlarged and schematic cross-sectional view of one embodiment of such a joint, showing a state in which the steel sheet piles of the embodiments of FIGS. 1 and 2 are fitted and connected, respectively. The steel sheet piles 1 and 1' are in contact with each other at their respective thermal sprayed coatings 3 and 3', thereby preventing seawater from entering the nails and preventing corrosion inside the nails. be. The effects of the present invention will be described in more detail with reference to Examples below. Example A steel sheet pile with a U-shaped cross-sectional shape shown in Fig. 3 and a web width of 125 mm and a flange width of 400 mm was cut into a length of 500 mm, and the entire surface was thoroughly grit-blasted. As shown in FIG. 3, a solvent-type epoxy resin paint was applied as anti-corrosion coating 2 to a dry film thickness of 300 μm on both sides except for the 300 μm and allowed to dry and harden naturally. Next, as shown in FIG. 3, 200 μm of aluminum corresponding to JISH8301 Class 1 was thermally sprayed as a thermal spray coating 3 to a portion adjacent to the above coating film, thereby forming a test specimen of an example of the present invention. Also, instead of the above thermal spraying, dry film thickness
A comparative test specimen was prepared with a 200μ tar epoxy coating. Three of these test specimens were fitted together at the joints, the cut surfaces were covered with asphalt agent, and the specimens were immersed in seawater for two years. Two years later, the test specimen was pulled up and the fitting was released, and the corrosion under the epoxy coating and the joint portion was investigated, and the following results were obtained. The superiority of the product of the present invention is clearly recognized. 【table】

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a heavy-duty anti-corrosion steel sheet pile with anti-corrosion coating applied only to the convex side, Figure 2 is a cross-sectional view of a heavy-duty anti-corrosion steel sheet pile with anti-corrosion coating applied only to the concave side, and Figure 3 is a cross-sectional view of a heavy anti-corrosion steel sheet pile with anti-corrosion coating applied only to the concave side. Fig. 4 is a perspective view schematically showing a heavy anti-corrosion steel sheet pile in which a portion of the convex side of the U-shaped steel sheet pile in the longitudinal direction is coated with anti-corrosion coating. FIG. 2 is an enlarged cross-sectional view schematically showing the state of a joint portion when the heavy corrosion-resistant steel sheet piles shown in FIGS. 1 and 2 are fitted and connected. 1, 1'... Steel sheet pile, 2, 2'... Anti-corrosion coating, 3,
3'...Thermal spray coating.

Claims (1)

[Claims] 1. A resin-based and/or mortar-based anti-corrosion coating is provided on the entire length or part of the longitudinal direction of one or both sides of the steel sheet piles at the parts that are exposed when the steel sheet piles are fitted together. A heavy-duty anti-corrosion steel sheet pile with excellent durability, characterized in that an aluminum or aluminum alloy thermal spray coating is provided on a portion adjacent to the anti-corrosion coating among the concealed portions.