JPH0536203B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for forming a protective film for protecting concrete and internal reinforcing bars of a concrete structure.

[Prior Art] Concrete structures are usually manufactured by constructing a formwork on the outside, arranging reinforcement reinforcing bars inside the structure, and then pouring concrete into the formwork. Concrete is strong against compressive loads, and the internal reinforcing bars handle tension and bending loads, so while it exhibits considerable strength against external forces, it has insufficient strength against temperature differences due to weather, rainwater, seawater, etc. However, the durability is particularly markedly reduced in the case of coastal and underwater structures.

The main reason for this is the porosity of concrete, which allows moisture from the surface to seep in and corrode the reinforcing steel inside. On the other hand, since concrete is alkaline, oxidation corrosion of reinforcing bars should be suppressed, but when moisture permeates into concrete, carbon dioxide in the air neutralizes the concrete, which prevents this corrosion. Significant decline.

In addition, in cold regions, water that has penetrated into concrete can freeze and cause damage to the concrete.Furthermore, in the case of coastal and underwater structures, in addition to the weather mentioned above, sea breeze, sea spray, and sea water can cause damage to the concrete. These factors further accelerate the corrosion of concrete and reinforcing steel.

In order to prevent this, in the invention of Japanese Patent Publication No. 12968/1983, a corrosion-resistant protective agent is applied to the inner surface of the mold before concrete is poured, and a protective film is formed on the surface of the hardened concrete.

[Problem to be solved by the invention] However, in the conventional method of forming a protective film, in order to successfully remove only the formwork after the concrete has solidified, it is necessary to apply a mold release agent to the inner surface of the formwork in advance. Furthermore, the adhesion of the protective film to the concrete was insufficient and there was a risk of it peeling off due to external force, and the surface of the protective film also had the disadvantage of being stained with mold release agent.

The present invention has been made in view of the above circumstances, and its purpose is to provide a method for forming a protective film for a concrete structure, which allows the formwork to be easily separated from the protective film without the need for a mold release agent. .

[Means for Solving the Problems] In order to achieve the above object, in the method for forming a protective film for a concrete structure according to the present invention, an adhesive is applied to the inner surface of a corrosion-resistant sheet provided with a thin film on at least the outer surface, and the corrosion-resistant The outer surface of the sheet is temporarily attached to the inside of the formwork, then concrete is poured into the formwork and allowed to harden, and finally the formwork is removed together with the outer film of the sheet.

[Function] With these configurations, the outer film portion of the corrosion-resistant sheet that serves as a protective film is temporarily attached to the inner surface of the formwork, so when the formwork is removed after the concrete has hardened, this film is also peeled off. On the other hand, the inside of the corrosion-resistant sheet and the concrete are tightly bonded together by the action of adhesive.

[Example] Figures 1A and B and Figure 2 show an example in which a pier support 1 is covered with concrete, and Figure 3 is a perspective view of a corrosion-resistant sheet used as a protective film. .

The pier is constructed by driving multiple steel pipe supports 1 into the sea.
Upper concrete 2 is formed by passing a steel material (not shown) over the top of each support column 1. Furthermore, since the ebb and flow area and the splash area of each support column 1 will corrode intensively due to the action of the macro battery if left as is, these areas are also covered with concrete to prevent corrosion.

In the concrete pouring work, first, a pedestal 3 that supports the formwork and serves as a foothold is attached around the column 1, and reinforcing bars 4 such as bolt studs are welded to the outside of the column 1. Next, a plurality of formworks 5 such as wooden boards are combined to cover the periphery of the support 1 in a rectangular tube shape, and the lower end of the formwork 5 is supported by the pedestal 3.

Next, as shown in FIG. 3, one end of the pre-rolled corrosion-resistant sheet 6 is pulled out and an epoxy adhesive 7 and a filler 8 are applied to its inner surface. The corrosion-resistant sheet 6 in this embodiment is formed by filling soft FRP between two Tetron films 9a and 9b, and the epoxy adhesive 7 is made of a base material and a hardening agent. A liquid mixing type is used. For the filler 8, an adhesion promoter, a viscosity modifier, a curing shrinkage inhibitor, etc., which increase the adhesive strength of the epoxy adhesive 7, are used as necessary.

Next, the above-mentioned corrosion-resistant sheet 6 is cut to a predetermined length and temporarily attached to the inner surface of the formwork 5 with an adhesive 10 as shown in FIG. 1A. Next, concrete 11 is poured between the formwork 5 and the support column 1 and allowed to harden.
Allow to cure for a specified period of time.

Finally, as shown in FIG. 1B, when the surrounding formwork 5 is removed, the outer film 9b of the corrosion-resistant sheet 6 is also peeled off together with it, and a protective film of the corrosion-resistant sheet 6 is formed on the surface of the concrete 11. on the other hand,
Since the concrete 11 and the corrosion-resistant sheet 6 are firmly adhered to each other by the epoxy adhesive 7 and the filler 8, the sheet 6 will not be easily peeled off even if it receives an external impact.

Incidentally, although the above-mentioned embodiment shows a case in which the support column 1 of a pier is covered with concrete, the method for forming a protective film of the present invention can be applied to various concrete structures.

[Effects of the Invention] As detailed above, in the method for forming a protective film for a concrete structure according to the present invention, when the formwork is removed after the concrete has solidified, the outer film of the corrosion-resistant sheet is also peeled off, while the sheet serving as the protective film is removed from the concrete. Since it adheres strongly to the sides, it has the effect of allowing the mold to be easily removed without the need for a mold release agent.

[Brief explanation of the drawing]

Figures 1A and B are construction state diagrams showing the protective film forming method of the present invention, Figure 2 is a front view of a concrete-covered pier support, and Figure 3 is a perspective view of a corrosion-resistant sheet used for the protective film. It is. 1... Support column, 3... pedestal, 4... Rebar, 5...
Formwork, 6...Corrosion-resistant sheet, 7...Epoxy adhesive, 9a, 9b...Tetron film, 11...
…concrete.

Claims (1)

[Claims] 1 Apply adhesive to the inner surface of a corrosion-resistant sheet with a thin film on at least the outer surface, temporarily attach the outer surface of the corrosion-resistant sheet to the inside of the formwork, then pour concrete into the formwork and allow it to harden, and finally A method for forming a protective film for a concrete structure, comprising: removing the formwork together with the outer film of the sheet.