JPH0243939Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field] The present invention relates to a deformed PC steel bar that is a steel material for prestressed concrete.

Conventionally, PC steel bars have been widely used in bridges. However, recently, PC steel bars have come to be used as hanging materials and binding materials for structures, taking advantage of their high tensile strength. When using prestressed steel rods as hanging rods or binding materials, all or part of the prestressed steel rods are not necessarily buried in the concrete structure and may be exposed to the external environment temporarily or permanently. Especially when this structure is an offshore structure such as a bridge connecting a strait or an island, the external environment is different from normal and is quite harsh, so corrosion under so-called stress effects has a negative effect on the material. , there is a risk of delayed fracture due to stress corrosion cracking phenomenon.

[Disclosure of the invention] The present invention provides a deformed prestressed steel bar that is resistant to damage during transportation and handling and has an anti-corrosion coating that does not impair the function of ribs such as threads formed on the surface of the deformed prestressed steel bar. This is what we intend to provide.

In order to achieve this objective, the present invention uses a powder coating layer of epoxy resin or polyethylene resin with a film thickness of 100 to 400 μm formed directly on the surface of a PC steel rod,
This is a deformed PC steel bar having a layer of heat-shrinkable polyethylene sleeve adhered to the surface of this powder coating layer.

Powder coating layers made of epoxy resin or polyethylene resin do not use solvents for coating, so they do not leave pores in the coating film and can form a coating with good corrosion resistance, but if the film thickness is less than 100 μm, there are problems in terms of corrosion resistance. If the film thickness is thicker than 400 μm, irregularly shaped PC
This will cause the ribs formed on the surface of the steel bar to lose their anchoring function, and in the case of fully threaded deformed PC steel bars, nuts will not be able to fit at the anchoring part. The thickness of the coating layer is 100 to 400 μm.

Thickness of heat-shrinkable polyethylene sleeve is 200
~800μm is used, and the total thickness with the powder coating layer is 300~1200μm. When heated, the heat-shrinkable polyethylene sleeve layer shrinks in circumference and becomes tightly integrated with the outer periphery of the powder coating layer to protect the powder coating layer and prevent the powder coating layer from peeling off due to external forces. Furthermore, when the heat-shrinkable polyethylene sleeve layer is subjected to external force, it acts as a buffer against the powder coating layer underneath, thereby preventing cracks from forming in the powder coating layer.

When the surface of a PC steel bar is covered only with a polyethylene sleeve or oil-based anti-corrosion tape, the thickness of this coating must be considerably thicker to withstand damage during transportation and construction. do not have. If the surface of the PC steel bar is coated thickly in this way, the ridges formed on the surface for anchoring to concrete will become gentle, reducing the anchoring function.

On the other hand, when the surface of a PC steel bar is galvanized or painted, a thin film provides corrosion protection, but it is easily damaged locally during transportation and handling, and if damaged, the may be subject to abnormal corrosive effects.

In contrast, in this project, the easily damaged paint film is tightly covered with a heat-shrinkable polyethylene sleeve to protect it, and the paint film is formed with a dense powder coating layer of epoxy resin or polyethylene resin. The heat-shrinkable polyethylene sleeve buffers against external forces and protects the powder coating layer, making it possible to reduce the overall thickness of the anti-corrosion coating and reducing the functionality of the anchor ribs formed on the deformed PC steel bar. do not have.

Fig. 1 is a partial side view of an embodiment of the deformed PC steel bar according to the present invention, Fig. 2 is a cross-sectional view, and Fig. 3 is a cross-sectional view of the deformed PC steel bar according to the present invention.
In the partially enlarged vertical cross-sectional view of the figure, 1 is a deformed PC steel bar, 2
is a threaded rib formed spirally over the entire length on its surface for anchoring to concrete and for fitting with a nut, 3 is a powder coating layer coated to a uniform thickness on the surface, and 4 is a powder coating. A layer of heat-shrinkable polyethylene sleeve closely adhered to the outer periphery of the paint layer 3. Note that the ribs 2 are not limited to those shown in this embodiment, and of course may have other shapes used in deformed PC steel bars.

[Brief explanation of the drawing]

Fig. 1 is a partial side view of one embodiment of the deformed PC steel bar of the present invention, Fig. 2 is a cross-sectional view of Fig. 1, and Fig. 3 is a cross-sectional view of Fig. 1.
FIG. 3 is a partially enlarged vertical cross-sectional view of the figure. 1... Deformed PC steel rod, 2... Rib, 3... Powder coating layer, 4... Layer of heat-shrinkable polyethylene sleeve.

Claims (1)

[Scope of utility model registration request] A powder coating layer of epoxy resin or polyethylene resin with a film thickness of 100 to 400 μm is formed directly on the surface of the PC steel rod, and a layer of heat-shrinkable polyethylene sleeve is applied to the surface of this powder coating layer. Deformed PC steel bar with.