JP2014141708A - Rust prevention method for reinforcing steel for lightweight aerated concrete panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rust prevention method for a reinforcing steel for lightweight aerated concrete capable of remarkably reducing the generation of pinholes formable in a rust preventive film.SOLUTION: Provided is a rust prevention method where a reinforcing steel for a lightweight aerated concrete panel is immersed into a rust prevention liquid, and thereafter, drying is performed to form a rust preventive film on the surface of the steel, in which the whole of the reinforcing steel is immersed in such a manner that th uppermost part upon the immersion of the reinforcing steel is located at a depth of at least 150 mm from the liquid face of the rust prevention liquid.

Description

  The present invention relates to a method for rust prevention of reinforcing reinforcing bars for lightweight cellular concrete (ALC) panels used for building walls, roofs, floors and the like.

  In the manufacture of ALC panels, siliceous raw materials such as silica and calcareous raw materials such as cement and quicklime are used as main raw materials, and additives such as water and aluminum powder are added to these fine powders to form a slurry. It is poured into a form in which reinforcing bars are arranged in advance. The injected slurry-like fluid is foamed by the reaction of the aluminum powder and further semi-hardened by the reaction of the calcareous raw material. The semi-cured body is cut into a predetermined size with a piano wire, and then subjected to high-temperature and high-pressure steam curing at about 180 ° C. and 10 atm by an autoclave. Thereby, an ALC panel having a predetermined dimension is obtained.

  The ALC panel thus obtained is lightweight because about 80% of its volume is in the form of bubbles and pores, and is also excellent in fire resistance, heat insulation, and workability. Widely used as building materials such as floors. However, the ALC panel has a structure that allows external moisture to easily enter the panel via the bubbles and pores, and unlike the ordinary concrete, ALC is weakly alkaline, so it is placed inside the ALC panel. Reinforced reinforcing bars are susceptible to corrosion. Therefore, the surface of the reinforcing reinforcing bar is subjected to rust prevention treatment in advance.

  As a method of applying a rust prevention treatment to the reinforcing steel bars, a method of immersing the reinforcing steel bars in a rust prevention liquid is common, but in such a dip coating method, air that is involved when the reinforcing steel bars are immersed in the rust prevention liquid is used. There was a problem that it stays on the surface of the reinforcing steel bars and causes rust prevention film defects (hereinafter referred to as pinholes) after drying. When pinholes are present in the rust preventive film, the reinforcing steel bars in the pinhole portions are not subjected to rust prevention treatment, and the reinforcing steel bars are corroded in the long term. If the corrosion of the reinforcing reinforcing bars is very small, the soundness as the ALC panel is maintained, but if the reinforcing reinforcing bars are corroded in a large amount, the soundness as the ALC panel is lost.

  In order to prevent this, it is important to reduce the number of pinholes formed in the rust preventive film as much as possible. For this reason, in claim 1 of Patent Document 1 as a conventional technique, a rust preventive liquid is applied to the reinforcing steel bars. In the rust preventive method, the rust preventive solution is alternately replenished from the rust preventive solution replenishment ports provided at both ends of the upper portion of the rust preventive solution tank, and disposed at both ends near the bottom of the rust preventive solution tank. A method of circulating a rust preventive liquid in a tank by a pump through a rust preventive liquid discharge port and an outlet is disclosed. Further, claim 2 of Patent Document 1 discloses a method of swinging in a horizontal direction while pulling up a reinforcing bar for ALC panel.

JP 2004-269908 A

When the method disclosed in claim 1 of Patent Document 1 is adopted in existing equipment, it is necessary to newly add a circulation equipment, so that the rust prevention treatment equipment needs to be remodeled greatly and the cost is increased. It will be. Furthermore, the size of the anticorrosion tank is huge, for example, about 1.5 m wide, about 7.2 m long, about 0.7 m high, and about 7.6 m ³ in capacity. There was a problem that it was not circulated uniformly. Further, in the method disclosed in claim 2 of Patent Document 1, the reinforcing bars for the ALC panel are swung in the horizontal direction. Therefore, in the size of the conventional antirust tank, the antirust tank and the reinforcing bars interfere with each other. There was a problem such as.

  The present invention has been proposed in view of the above-mentioned problems. The object of the present invention is to provide a rust preventive method in which a reinforced anticorrosive film is formed by immersing a reinforcing bar for lightweight cellular concrete in a rust preventive liquid. An object of the present invention is to provide a rust prevention method for reinforcing reinforcing bars for lightweight cellular concrete that can greatly reduce the occurrence of pinholes that can be formed in a rust coating.

  To achieve the above object, the present invention provides a method for rust prevention of reinforcing reinforcing bars for lightweight cellular concrete panels, which is obtained by immersing reinforcing reinforcing bars for lightweight cellular concrete panels in an anticorrosive solution, and then drying them on the surface of the reinforcing bars. A rust-preventing method for forming a rust-preventing coating, characterized by immersing the entire reinforcing steel bar so that the uppermost portion when the reinforcing steel bar is immersed is located at a depth of at least 150 mm from the surface of the anticorrosive liquid .

  Further, the present invention provides a method for manufacturing a reinforced reinforcing bar on which a rust preventive coating for lightweight cellular concrete is formed, a step of immersing the reinforcing bar in a rust preventing liquid, and a rust preventing liquid applied to the surface of the reinforcing bar by the immersion. The entire reinforcing steel bar is dipped so that the uppermost part when the reinforcing steel bar is immersed is located at a depth of at least 150 mm from the liquid surface of the rust preventive liquid.

  According to the present invention, pinholes that are likely to be formed on the surface of a lightweight reinforcing concrete for cellular concrete are greatly reduced without the need for new equipment, and a coating having an excellent rust-preventive effect can be made inexpensively on the surface of the reinforcing bar. Can be formed. Since the lightweight cellular concrete panel using the reinforcing reinforcing bar on which the anticorrosive coating is formed can prevent corrosion of the reinforcing reinforcing bar over a long period of time, an extremely reliable ALC panel can be provided.

It is a perspective view of the general reinforcement bar embed | buried under the inside of an ALC panel. It is a perspective view of the rust prevention apparatus used suitably for the rust prevention method of this invention.

  Hereinafter, embodiments of the rust prevention method for reinforcing reinforcing bars for ALC panels according to the present invention will be specifically described with reference to the drawings. As shown in FIG. 1, inside the ALC panel P, a plurality of main bars 1a extending in the longitudinal direction of the ALC panel P and a plurality of horizontal bars 1b extending in the transverse direction perpendicular thereto are welded to each other. A reinforcing reinforcing bar 1 called a reinforcing steel mat formed into a basket shape is embedded. When this reinforced reinforcing bar 1 is subjected to a rust prevention treatment by the dip coating method described above, it is preferable to immerse a plurality of reinforcing reinforcing bars 1 in a rust preventive solution at a time, thereby enabling efficient rust prevention work. .

  Therefore, for example, a fixing jig 2 as shown in FIG. 2 is used. The fixing jig 2 has a rectangular flat plate shape, and a plurality of support rods 3 extending vertically from the plate surface are disposed on one plate surface thereof. By attaching the reinforcing bars 1 to the support bars 3 so as to be along the support bars 3, it is possible to attach the plurality of reinforcing bars to the fixing jig 2 in an aligned state.

  The plurality of aligned reinforcing bars 1 are arranged so that all the main bars extend substantially parallel to the plate surface of the fixing jig 2 and all the distances between the main bars closest to the plate surface and the plate surface are substantially the same. preferable. Thereby, a uniform rust preventive film without variation between reinforcing reinforcing bars can be formed. In this way, the fixing jig 2 to which the plurality of reinforcing bars 1 are attached is suspended so that the plate surface on the support rod 3 side faces directly below as shown in FIG. In the example of FIG. 2, two reinforcing reinforcing bars 1 are arranged in the longitudinal direction of the fixing jig 2, and a plurality of reinforcing reinforcing bars 1 are arranged in the short direction.

  After the fixing jig 2 to which the plurality of reinforcing bars 1 are attached is moved directly above the rust prevention tank 4 filled with the rust prevention liquid, the fixing jig 2 is gradually lowered as it is, so that the plurality of reinforcing bars 2 1 can all be immersed in the same depth of rust preventive liquid. After being immersed for a predetermined time in this state, the fixing jig 2 is pulled up, and the rust preventive liquid applied to the surface of the reinforcing bar is dried. Thereby, a rust prevention film can be formed on the surface of each reinforcing bar which constitutes reinforcing reinforcing bar 1.

  At the time of immersion of the reinforcing reinforcing bars, the entire reinforcing reinforcing bars are immersed so that the uppermost portion when the reinforcing reinforcing bars are immersed is located at a depth of at least 150 mm from the liquid surface of the antirust solution. As a result, all the reinforcing bars constituting the reinforcing bars can be immersed in a position deeper than 150 mm from the surface of the rust preventive liquid, so that pinholes that are easily formed on the surface of the rust preventive film can be greatly reduced. Thus, it is possible to form a rust preventive film with fewer pinholes on the surface of each reinforcing bar than in the past. Therefore, it is possible to provide an ALC panel having a high rust prevention effect over a long period of time. Hereinafter, an example is given and it demonstrates in detail.

  Using a plurality of main bars with an outer diameter of 5.5 mm and horizontal bars with an outer diameter of 4.0 mm each, a cage-shaped reinforcing steel bar that fits inside a lightweight cellular concrete panel with a thickness of 100 mm, a width of 600 mm, and a length of 3540 mm A plurality of (thickness 70 mm, width 496 mm, length 3512 mm) were produced. These reinforcing bars were immersed in rust preventive liquids at different depths, and the state of the rust preventive coating when the film was formed was examined.

  A flat fixture 2 having a width of 1500 mm and a length of 7200 mm as shown in FIG. 2 was used for the immersion. A plurality of support rods 3 are erected on one plate surface of the fixing jig 2, and a total of 30 supporting rods 2 in the longitudinal direction and 15 in the lateral direction of the fixing jig 2 are arranged along these. Reinforcing bars 1 were attached side by side. The main reinforcing bar and the horizontal reinforcing bar of each reinforcing steel bar 1 were extended in parallel and perpendicular to the plate surface of the fixing jig 2, respectively.

  The other plate surface of the fixing jig 2 is provided with eyebolts at four corners. The chain of the chain block is hooked on this, the chain block is driven, and the plate surface of the fixing jig 2 on the support rod 3 side is directly below. Lifted to face. As a result, the main bar and the horizontal bar of the reinforcing reinforcing bar 1 fixed to the support bar 3 were extended in the horizontal direction and the vertical direction, respectively. In this state, after moving the fixing jig 2 to above the rust prevention tank 4 filled with the rust prevention liquid, the fixture 2 is lowered at a descending speed of 20 mm / second, and all the reinforcing steel bars 1 are protected from the rust prevention tank 4. It was completely immersed in the rust solution.

  At the time of immersion, the immersion depth from the liquid surface of the anticorrosive solution to the uppermost part when the reinforcing steel bar is immersed (that is, the one closest to the fixing jig 2 among the plurality of main reinforcing bars) is 5 mm. Adjusted the height of the chain block. In addition, the rust preventive liquid contains SBR aqueous emulsion, asphalt aqueous emulsion, and alkaline earth metal carbonate powder as a solid content, and rust preventive liquid mixed with slaked lime for adjusting pH and water for adjusting viscosity. used. In addition, in the rust prevention treatment, the number of times of immersion in the rust prevention liquid was only once.

  After the fixing jig 2 was pulled up from the rust preventive liquid to complete the immersion, the rust preventive liquid applied to the surface of the reinforcing bar was dried by passing it through a tunnel adjusted to approximately 50 ° C. for approximately two hours. In this way, a reinforcing bar of Sample 1 on which a rust preventive film was formed was produced. Further, the same as in Sample 1 above, except that the immersion depth from the surface of the rust preventive solution during immersion to the uppermost part of the reinforcing steel bars was changed to 50 mm, 50 mm, 100 mm, 150 mm, 200 mm, and 300 mm, respectively. Reinforcing bars for Samples 2 to 6 on which a rust film was formed were prepared.

  The number of pinholes formed on the anticorrosion film of the reinforcing bars of the reinforcing bars of Samples 1 to 6 was counted visually to obtain the average number of pinholes per reinforcing bar of the reinforcing bars. In addition, the reduction rate of the number of pinholes based on the average number of pinholes of the sample 1 almost corresponding to the conventional immersion depth is obtained, and a reduction rate of 75% or more is appropriate, and the reduction rate is less than 75%. Was evaluated as inappropriate. The results are shown in Table 1 below together with the immersion depth from the surface of the rust preventive liquid to the top of the reinforcing steel bars.

  As can be seen from the results in Table 1 above, in Samples 4 to 6 (immersion depth of 150 mm or more), the reduction rate of the number of pinholes was 75% or more, and good results were obtained. However, since the effect of reducing pinholes becomes smaller at an immersion depth of 150 mm, the effect does not change much even if the immersion depth is deeper than 150 mm, and it is rather uneconomical. On the other hand, in Samples 1 to 3 (immersion depth less than 150 mm), the reduction rate of the number of pinholes was less than 75%, and preferable results were not obtained.

DESCRIPTION OF SYMBOLS 1 Reinforcing bar reinforcement 2 Fixing jig 3 Support rod 4 Anticorrosion tank P ALC panel

Claims (2)

  This is a rust prevention method in which a reinforcing steel bar for lightweight cellular concrete panels is immersed in a rust preventive liquid and then dried to form a rust-preventive coating on the surface of the reinforcing bar. A method for rust prevention of a reinforcing bar for lightweight cellular concrete, wherein the entire reinforcing bar is immersed so as to be located at a depth of at least 150 mm from the liquid surface.   A method of manufacturing a reinforcing steel bar in which a rust-proof coating for lightweight cellular concrete is formed, which comprises a step of immersing a reinforcing steel bar in a rust-proof solution and a step of drying the rust-proof solution applied to the surface of the steel bar by the immersion. The reinforcement reinforcing bar having a rust-preventing coating formed by immersing the entire reinforcing reinforcing bar so that the uppermost portion when the reinforcing reinforcing bar is immersed is at least 150 mm deep from the surface of the rust prevention liquid. Method.

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