JP6038449B2 - Resin coated anti-corrosion PC steel - Google Patents

Description

  The present invention mainly relates to a resin-coated anticorrosion PC steel used as an oblique cable for a cable-stayed bridge.

This type of resin-coated anticorrosion PC steel can be described, for example, with reference to FIGS. 1 and 2 showing an embodiment of the present invention, and a PC steel wire (PC steel wire) obtained by twisting a plurality of strands 1a. Strand) 1, wax 2 applied and interposed between the outer periphery of the PC steel wire 1 and the strand 1 a, and a resin coating 3 coated around the PC steel wire 1 with the wax 2 interposed therebetween (Patent Document 1, Claim 1, FIG. 1).
For example, the PC steel material W is obtained by passing the PC steel wire material 1 in which the strands 1a are twisted through a high-pressure wax bath and applying and interposing a wax between the entire outer circumference and each strand 1a. The resin wire 3 is manufactured by extruding a polyethylene resin or the like on the outer peripheral surface of the steel wire 1 (see Patent Document 1, paragraph 0003, FIG. 1, etc.). In particular, the resin-coated anticorrosion PC steel material in which the surface of the element wire 1a is galvanized is referred to as a triple anticorrosion strand due to galvanization, wax coating and resin coating 3.

If this resin-coated anti-corrosion PC steel material is used as a cable cable for cable-stayed bridges, it will be used under severe conditions where it is directly exposed to wind and rain and sea breezes. When the intrusion occurs, the steel wire 1 (elementary wire 1a) rusts and the mechanical strength (function) is reduced. For this reason, in order to prevent the intrusion (to ensure the effectiveness of rust prevention), an airtight test for evaluating the presence or absence of a leak path is performed before the on-site enforcement (before shipment).
In this airtightness test, for example, as shown in FIG. 3, one end of a 500 mm long PC steel W is immersed in a water tank B, and 0.2 MPa × 30 seconds of air is applied to the other end with an air cylinder C. Then, whether or not the air leaks from one end (the presence or absence of a leak path) is measured. The presence or absence of the leak path is determined by whether or not bubbles are generated in the water tank B. In FIG. 3, A is a support for PC steel W made of L-shaped metal fittings.

JP 2003-193622 A

  Conventionally, in the above airtightness test, a leak path is generated in about 40% of the PC steel material W, and the pass rate is as low as about 60%.

  This invention makes it a subject to prevent the leak path | pass of the said PC steel materials.

The inventor of the present invention pays attention to the fact that the water intrusion into the PC steel material is carried out from the end portion. If at least the end portion has a water infiltration preventing structure, even if a leak path occurs in the entire inner length of the PC steel material. The PC steel material as a whole can be assumed to have no leak path.
With this in mind, in order to achieve the above object, the present invention, in order to the prevent flooding structure PC steel end, it was a Rukoto to disperse adding water-absorbing polymer in the wax of its ends.
Since the water-absorbing polymer absorbs water within a few seconds after contact with water to expand the wax layer and enhance the water tightness (water blocking property) of the end portion, water intrusion from the end portion is prevented. For this reason, an internal PC steel wire becomes difficult to be corroded by water.

As a structure of this invention, the PC steel wire 1 which twisted together the said some strand 1a, the wax 2 apply | coated and interposed between the outer periphery of the PC steel wire 1 and the said strand 1a, and the said PC steel In a resin-coated anticorrosion PC steel material comprising a resin coating 3 coated with a wax 2 around a wire 1, a water-absorbing polymer 4 is added to and dispersed in the wax 2 at least at the end of the PC steel wire 1. Can be adopted.

In this configuration, grease can be employed instead of the wax 2, and sodium polyacrylate or the like can be employed as the water-absorbing polymer.
The addition of the water-absorbing polymer to the wax layer at the end of the PC steel material can be made by adding the water-absorbing polymer only to the wax at the end, and the length of the end is effective for preventing flooding. What is necessary is just to determine suitably by experiment etc. so that security can be ensured. However, since the addition to only the end portion is complicated, if all waxes over the entire length of the PC steel material are added with a water-absorbing polymer, the PC in the wax tank is the same as before. Wax application and interposition can be performed by passing the steel wire 1. In this case, the water-absorbing polymer is mixed (added and dispersed) to all of the wax 2 around the PC steel wire 1 and between the strands 1a.
Further, the mixing ratio of the wax 2 and the water-absorbing polymer may be appropriately set by experiments or the like so as to prevent water intrusion at the end portion.
Water-absorbing polymer with respect to 0: 15 or more and 100 or less.

  Since this invention was made into PC steel materials comprised as mentioned above, it can prevent the water immersion inside PC steel materials effectively, and can raise the pass rate in the above-mentioned airtightness test.

Partial perspective view of one embodiment of PC steel according to the present invention End cut view of the same embodiment Airtightness test explanatory diagram of the same embodiment

  As shown in FIGS. 1 and 2, the PC steel material of this embodiment is a PC steel obtained by twisting together a plurality of surface galvanized steel strands (diameter: 19.0 ± 0.8 mm) 1a as shown in FIGS. A wire 1, a wax 2 applied and interposed between the outer periphery of the PC steel wire 1 and the element wire 1 a, and a polyethylene resin coating 3 coated around the PC steel wire 1 with the wax 2 interposed Become. This PC steel W is also made by passing the PC steel wire 1 through a wax bath added with a high-pressure water-absorbing polymer 4 and applying and interposing the water-absorbing polymer mixed wax 2 between the entire outer periphery and each strand 1a. The PC steel wire 1 was produced by extruding a polyethylene resin or the like on the outer peripheral surface of the PC steel wire 1 to form a resin coating 3. At this time, the addition (mixing) of the water-absorbing polymer 4 to the wax 2 is performed by adding and kneading the water-absorbing polymer 4 to the normal temperature wax 2 and further passing the wax 2 between the rollers to uniformly disperse the water-absorbing polymer 4. Alternatively, the wax can be heated to be liquefied, and a powdery water-absorbing polymer can be put in it, mixed by stirring and dispersed uniformly, and then rapidly cooled and solidified in the dispersed state.

In PC steel W manufactured as described above, Test Examples 1 to 11 having the blending ratios shown in Table 1 were produced, and the results of the airtightness test shown in FIG. Shown in In Table 1, in each ratio (ratio) of the water-absorbing polymer 4 with respect to the wax (hydrocarbon type) 2, “◯” indicates that no bubbles are generated in the water tank W, and no leak path is generated. “X” indicates that bubbles appear in the water tank W and a leak path appears to be generated.
Trade name: CIRINJECT CP-HPF was used for wax 2, and trade name: Aquakeep 10SH-NF (water absorption 60 g / g, water absorption speed 8 seconds, particle size 106 μm) was used for water-absorbing polymer 4. . In the water absorption test, 5 g of water was dropped on about 15 g of wax 2 and the time until the wax 2 completely absorbed water was evaluated. did.

From this test result, it is understood that if the water-absorbing polymer 4 is added to the wax 2 and the weight ratio of the water-absorbing polymer is 15 or more with respect to the wax: 100, mixing / coating is possible and no leak path occurs. it can. However, when the amount exceeds 100 parts by mass, the water-absorbing polymer 4 becomes the main component of the cloud, and there is a concern that the storage stability is reduced due to moisture absorption. Therefore, the amount of the water-absorbing polymer 4 added is 100 parts by mass or less.
In this type of PC steel W, similar results could be obtained even when the same grease was used as the grout material instead of the wax 2.

  The resin coating 3 is not polyethylene resin, but polypropylene resin, polyphenylene ether (PPE), polyamide resin, phenoxy resin, polycarbonate, acrylonitrile butadiene styrene (ABS) resin, polystyrene, polyacetal, polyethylene terephthalate (PET). Polyarylate, epoxy resin, polyester resin, acrylic resin, polyurethane resin, silicone resin, phenol resin, polyolefin-based polyethylene, etc. can be adopted, and the resin coating 3 is mixed with a pigment such as carbon to provide weather resistance. It is preferable to increase. Further, the number of strands of the wire 1a is not limited to seven, but may be 19 or the like. Thus, it should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 PC steel wire 1a Steel wire (elementary wire)
2 Wax 3 Resin coating 4 Water-absorbing polymer W Resin coated anti-corrosion PC steel

Claims (2)

PC steel wire (1) obtained by twisting a plurality of strands (1a), the outer periphery of the PC steel wire (1) and the wax (2) or grease coated between the strands (1a), A resin-coated anti-corrosion PC steel material comprising a resin coating (3) coated with a wax (2) or grease around a PC steel wire (1), at least an end portion of the PC steel wire (1) The wax (2) or grease is added with a water-absorbing polymer (4) and dispersed therein, and the dispersed water-absorbing polymer (4) absorbs water at the end of the PC steel wire (1). A resin-coated anti- corrosion PC steel having a water-inhibiting structure in which a layer or a grease layer expands to improve water tightness .   2. The resin according to claim 1, wherein the water-absorbing polymer (4) in the wax (2) or grease has a mass ratio of the water-absorbing polymer: 15 to 100 with respect to the wax or grease: 100. Coated anticorrosion PC steel.

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