JPS6040969B2 - Corrosion prevention treatment method for cables - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention mainly relates to a method for anticorrosion treatment of cables used in suspended structures such as cable-stayed bridges and suspended roofs.

When anti-corrosion treatment is performed by injecting a filler 3 between a cable 1 and a cladding tube 2 as shown in the cross-sectional structure of FIG. 1, boltland cement has conventionally been used as the filler 3.

In this type of method, it is required that the inner filling material can protect the cable 1 from corrosion even if the cladding 2 deteriorates, but this is especially true for cables used in suspended structures such as cable-stayed bridges. When Bolland cement was used as the filler 3, large cracks 4 were formed as shown in FIG. 2, and the anticorrosion effect was significantly reduced. In other words, the filler is injected after the dead load has been applied to the cable, so the tensile stress acting on the filler is caused only by the live load, but cables used for suspended structures, etc., have large fluctuating stress due to the live load. Compared to cables, Boltland cement has a relatively large elongation with respect to tensile stress of 4.0 and a relatively large Young's modulus, so it cannot follow the elongation of the cable when a varying tensile stress is applied, resulting in large cracks.
For example, when a tensile stress of 20k9/rock is applied to the cable, the elongation rate of the cable is 0.1%, whereas with Boltland cement, the elongation at break is about 0.05%.
0.05% of the difference corresponds to the crack. It is said that there is no problem in terms of corrosion protection if the cracks in the filler are 0.1 mm or less, and the elongation is sufficiently large compared to Boltland cement to reduce the cracks to this extent.

It is necessary to use a material (soft material) with a Young's modulus of 4 as a filler. Therefore, a soft material such as chisote rubber that satisfies these requirements has been considered, but rubber is several tens of times more expensive than Boltland cement, which poses a major practical drawback in terms of cost.
In view of these circumstances, the present invention uses Boltland cement to which rubber latex or resin emulsion is added as a filler for cable corrosion protection, thereby maintaining a relatively low cost while creating a suspended structure with large fluctuating stress due to live loads. The purpose of the present invention is to provide a method for anticorrosion treatment of cables, which can improve the elongation and Young's modulus of the filler material for cables using the present invention, and can significantly enhance the anticorrosion effect.

To explain the method of the present invention in detail, for example, in order to obtain a cross-sectional shape as shown in FIG. In the injection and filling method, a polymer cement obtained by adding water-soluble rubber latex or resin emulsion to Bortland cement is used as the filler 2. By mixing rubber or the like into cement in this way, the elongation at break increases and the Young's modulus decreases. Additionally, this polymer cement is only slightly more expensive than conventional Boltland cement, but much cheaper than rubber. The following table shows experimental results on how mechanical properties change depending on the amount of rubber latex mixed into cement.

[Table 1] Water [*1] Water/cement ratio = Dried size Koika rubber [*2] Polymer ratio = Bortland cement (wt%
) Styrene-butadiene rubber was used as the added rubber.

As is clear from the table above, as the amount of rubber added (increasing the polymer ratio) increases within the range shown in the table, the elongation at break increases and the Young's modulus decreases. From the perspective of the cable's function as a corrosion-preventing filler, the change in properties means that it has better ability to follow the elongation of the cable due to live loads, and the cracks in the cracks have become smaller, increasing the corrosion-preventing effect and providing good results. Therefore,

In other words, assuming that the tensile fluctuating stress due to the live load of a cable used in a cable-stayed bridge is 20k9/journey, and the elongation of the cable at this time is 0.1%, the elongation of the filler at break is 0. It is required that it be .1% or more, so please take care of it. The polymer ratio was adjusted to 1 to obtain an elongation of 2%.
5% is sufficient and inexpensive. And water
When a tensile fatigue test was conducted using a material with a cement ratio of 42% and a cross-sectional shape as shown in Figure 1, it was found that during cracking of the filler after a tensile fluctuation stress of 20k9/average was applied 2 million times, the polymer With a ratio of 0 (conventional Voltland cement alone), it is 0.1 to 0.15 cape, but with a polymer ratio of 15%, it is 0.05 cape or less, which is 0.1 cape in cracks, which is acceptable for corrosion protection. Very good results were obtained, which was much smaller than the previous one. In the above embodiments, styrene-butadiene rubber was used as the additive, but similar characteristics can be obtained when other rubber latexes or resin emulsions are added.

The following Table 2 summarizes the above points and compares and contrasts the mechanical properties of the filler and the tensile fatigue test results between the present invention and the conventional example.

[Table 2] [*] Tensile stress 20k9/fine, values in cracks after 200 cycles of tensile fatigue test are shown.

In addition, in the method of the present invention, the polymer ratio of Boltland cement as a corrosion-preventing filler can be varied depending on the elongation of the cable due to the expected live load depending on the application. It is sufficient to select a ratio that is as inexpensive as possible within a sufficiently small range.

However, if the polymer ratio exceeds 30 to 40%, curing will not occur, so the polymer ratio is preferably in the range of 5 to 30%.
As mentioned above, the cable anti-corrosion treatment method of the present invention uses polymer cement, which is made by adding rubber latex or resin emulsion to cement, as the anti-corrosion filler to fill the gap between the cable and the cladding, so it is relatively simple. While keeping costs low, we have increased the elongation of the filler at break to the extent that it can sufficiently follow the elongation of the cable even when large tensile stress due to live load is applied to the cable used in suspension structures. The Young's modulus can be reduced, and the cracks in the filler can be made very small.
This greatly enhances the corrosion protection effect of the cable.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the shape of a cable subjected to anti-corrosion treatment, and FIG. 2 is a side view of important points showing how cracks occur in the filler due to the conventional anti-corrosion treatment method. 1...Cable, 2...Sheathing material, 3.
...Anti-corrosion filler. Figure 1 Figure 2

Claims (1)

[Claims] 1. In a method of anti-corrosion treatment of a cable by filling the gap between the cable and the cladding with an anti-corrosion filler, the cable and the cladding are treated using polymer cement added with rubber latex or resin emulsion as the anti-corrosion filler. An anti-corrosion treatment method for cables, characterized by filling the space between the cables.