JPH0613165B2 - Protective film for concrete structure and its formation method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a protective film for protecting concrete of a concrete structure and internal reinforcing bars, and a method for forming the same.

[Prior Art] A concrete structure is usually manufactured by forming a mold on the outside and arranging reinforcing bars inside, and then pouring the concrete into the mold. Concrete is strong against compressive load, and since internal reinforcing bars bear tensile and bending loads, it exhibits considerable strength against external forces, but
The strength against temperature difference, rainwater, seawater, etc. due to the weather is insufficient, and the durability is remarkably reduced especially in the case of a bay or an underwater structure.

The main cause of the decrease in durability is the porosity of concrete, from which water from the surface penetrates and corrodes the internal reinforcing bars. On the other hand, since concrete is alkaline, oxidative corrosion of reinforcing bars should be suppressed, but when water penetrates into the concrete, carbon dioxide in the air neutralizes the concrete, so Is significantly reduced.

In cold regions, the water that permeates the concrete freezes and causes damage to the concrete. These further accelerate corrosion of concrete and rebar.

In order to prevent this, in the invention of Japanese Examined Patent Publication No. 63-12968, a corrosion-resistant protective agent is applied to the inner surface of the mold, and then concrete is poured in to form a protective film on the surface of the solidified concrete.

[Problems to be Solved by the Invention] However, with the above-mentioned protective film, the adhesion of the protective film to concrete cannot be said to be sufficient, and if a strong adhesive is not simply used, it will become brittle and the earthquake will occur. The vibration may cause the protective film to peel off. Further, even if the protective film is formed long in advance, it cannot be rolled and stored or transported because of its high rigidity.

The present invention has been made in view of the above circumstances, and an object thereof is to protect a concrete structure that can be wound in advance and transported before use, has high adhesion after use, and can flexibly cope with vibration. A film and a method for forming the film are provided.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the protective film of claim (1) is such that a water-curable adhesive is attached to one surface of a soft sheet having corrosion resistance with an elastic adhesive and the surface thereof is It is covered with a peelable film.

Further, in the method for forming a protective film according to claim (2), the film of the protective film is peeled off, and temporarily fixed to the inside of the mold, and then concrete is poured into the inside of the mold to be solidified, and finally the mold is formed. Is removed.

[Operation] According to the configuration of claim (1), since the sheet and each adhesive have flexibility, it is convenient for storage and transportation if a protective film is formed in advance and wound, and the surface of the protective film. Since the film is covered with a film, the water-curable adhesive does not react with moisture in the air.

According to the constitution of claim (2), the water-curable adhesive on the inner surface of the sheet causes a hydration reaction with the concrete to increase the adhesive force between the sheet and the concrete, and the elastic adhesive is used even if the structure shakes due to an earthquake or shock. As it follows while absorbing
Generation of cracks and peeling of the protective film are prevented.

EXAMPLE FIG. 1 and FIG. 2 show a perspective view and an enlarged sectional view of a protective film 1 according to the present invention. The protective film 1 is elastic on one surface of a corrosion-resistant soft sheet 2. The water-curable adhesive 3b is attached with the adhesive 3a, and the surface thereof is a peelable film 4
It is constituted by coating with.

The soft sheet 2 is preferably made of FRP and has flexibility enough to wind the protective film 1 formed long. The elastic adhesive 3a is a binder that bonds the water-curable adhesive 3b to the sheet 2 and is already commercially available. This is an adhesive that has elasticity like rubber even after curing, absorbs vibrations and shocks, and can follow the sheet 2 even when wound.

The water-curable adhesive 3b is a material that is hardened and bonded by a hydration reaction, and in this embodiment, a cement-based granular adhesive having a diameter of about 1 mm is used. The film 4 on the surface is the adhesive 3b
It is preferable to use a type that can be easily peeled off by hand because it prevents the reaction with water in the air.

Next, according to FIGS. 3 and 4 (A) and (B), the pier supports 5
The case of coating with concrete will be described.

The pier is constructed by forming concrete 6 on the stanchions 5, and the metal stanchions 5 are likely to be corroded intensively in the tidal and splash areas, so that this area is also covered with concrete. In pouring concrete, first, a pedestal 8 that serves as a scaffold for the formwork 7 is attached around the column 5, and a reinforcing bar 9 such as a bolt stud is welded to the outside of the column 5. Next, a plurality of molds 7 such as wooden boards are combined to cover the periphery of the column 5 in a rectangular tube shape, and the lower end of the mold 7 is supported by the pedestal 8.

Next, the above-mentioned protective film 1 is pulled out and cut into a predetermined length, the film 4 on the surface is peeled off, and then temporarily fixed to the inside of the mold 7 with an adhesive 10 as shown in FIG. 4 (A). Then, concrete 11 is poured between the formwork 7 and the support 5 to be solidified and cured for a predetermined time. During this time, the water-curable adhesive 3b reacts with the water content of the concrete 11 and hardens, so that the protective film 1 and the concrete 11 firmly adhere to each other. Finally formwork 7
Since the fixing force on the concrete side is stronger than that on the mold frame 7 side, the protective film 1 remains on the surface of the concrete 11.

Therefore, the adhesive strength between the concrete 11 and the protective film 1 is mainly maintained by the water-curable adhesive 3b, and the elastic adhesive 3a follows the earthquake and vibration while absorbing them. The protective film 1 does not peel off.

The protective film and forming method of the present invention are not limited to the above-mentioned jetty and can be applied to various concrete structures.

[Effects of the Invention] As described in detail above, according to the protective film and the method for forming the same of the present invention, the protective film can be wound and stored before being used, and after use, the protective film firmly adheres to the surface of the concrete. At the same time, it is effective in improving seismic isolation and impact resistance due to elasticity and flexibility.

[Brief description of drawings]

FIG. 1 is a perspective view of a protective film according to the present invention, FIG. 2 is an enlarged sectional view thereof, FIG. 3 is a front view of a concrete-supported jetty column, and FIGS. 4 (A) and 4 (B) are protective films. It is a construction state figure of a formation method. 1 ... Protective film, 2 ... FRP soft sheet, 3a ... Elastic adhesive, 3b ... Hydrosetting adhesive, 4 ... Peelable film, 5 ... Pier support, 7 ... Formwork, 11 …concrete

Claims (2)

[Claims] 1. A protective film for a concrete structure, comprising a flexible sheet having corrosion resistance, a water-curable adhesive attached to one side of the sheet with an elastic adhesive, and the surface of which is covered with a peelable film. 2. The protective film according to claim 1 is peeled off and temporarily fixed to the inside of the form, concrete is then poured into the form to solidify, and finally the form is removed. Method for forming a protective film on a concrete structure.