JP2002275832A - Repairing method of reinforced concrete member deteriorated by salt damage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a repairing method of a reinforced concrete member deteriorated by salt damage for preventing progress of corrosion of a reinforcement at execution work, and reducing a repairing execution cost by repairing and executing a deteriorated part of the reinforced concrete member in a short time as much as possible. SOLUTION: Concrete 1 of a repairing place is chipped off up to the reverse of the reinforcement 2. Powder and grain including quickly coagulating cement is sprayed on the repairing place under high pressure. Cement mortar 4 having high salt insulating performance, and causing little a crack is sprayed on the surface layer in a wet process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for repairing a section of reinforced concrete which is severely degraded by salt damage, and is particularly applicable to an environment where salt corrosion is severe.
The present invention relates to a method for repairing reinforced concrete members deteriorated by salt damage.

[0002]

2. Description of the Related Art If salt adheres to the surface of a reinforced concrete structure in a corrosive environment with severe salt damage, the reinforced steel rusts, causing problems with the load-bearing capacity of the structure itself.
Repair of the reinforced concrete member deteriorated in such a manner has been frequently performed in recent years.

[0003] In order to solve this problem, the conventional method of repairing a cross section is to use a method in which deteriorated concrete is suspended to the back side of a reinforcing bar, a formwork is installed on the repaired portion, a filler having a high salt barrier property is injected, and furthermore, from outside. The surface was painted to prevent chlorides from penetrating. However, after concrete has been stripped, irregularities remain on the surface of the stripped part, and when the irregular surface is the lower surface of beams or floor slabs, filling the filler often leaves voids. There is a problem that the cost is high and the repair cost is high.

A cross-section repairing method by spraying has also been conventionally practiced, but this method is a method in which mortar which has been previously kneaded is sprayed onto the concrete surface by air pressure. It is about 30 mm, and it is necessary to perform spraying over several days, during which corrosion of the reinforcing bar progresses and chloride ions are highly likely to adhere during several spraying operations.

[0005] By adding a quick-setting agent to the mortar that has been previously kneaded, it is possible to apply a thickness of several tens of mm or more by adding a quick-setting agent immediately before spraying. However, it is difficult to mix the quick-setting agent uniformly and the quality is poor. Since it is not stable, it cannot be applied to the repair of concrete members that have deteriorated due to salt damage.

[0006]

The object of the present invention is to repair a deteriorated portion of a reinforced concrete member in as short a time as possible in an environment where deterioration due to salt damage is severe, and corrosion of the reinforcing bar progresses during the construction. Provided is a method for repairing a reinforced concrete member that has deteriorated due to salt damage and that can reduce the cost of repair work.

[0007]

SUMMARY OF THE INVENTION According to the present invention, concrete at a repair site for reinforced concrete is suspended to the back surface of a reinforcing bar, and a powder containing cement, which has a rapid setting, is pneumatically fed.
A method of repairing a reinforced concrete member deteriorated by salt damage by mixing it with water just before spraying, spraying the mixture onto the repaired portion, and attaching a cement mortar having a high salt barrier property and less likely to generate cracks to the surface layer.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an image sectional view at the time of construction using the repair method of the present invention in one embodiment.

First, concrete 1 in a deteriorated portion requiring repair of reinforced concrete is scraped off to the back surface of reinforcing bar 2 as shown in the figure, and the construction procedure is the same as that of the conventional section repair method.

[0010] Next, a sand mixture cement in which dry cement is kneaded with fast-setting cement as a granular material containing fast-setting cement is mixed with water immediately before spraying at a repair location, and the sand is mixed with water at a relatively high pressure. The cement mortar 3, which sets quickly, is applied by dry spraying.

[0011] By spraying the cement mortar 3, which has a high degree of setting, at a high pressure onto the uneven surface thus removed, voids are not left, and a reliable spraying operation is performed on the repaired portion.

[0012] Moreover, the cement mortar 3 having a fast setting time
Can increase the spraying thickness, and repair the cross section by this spraying method up to about 20 mm before the final finished surface or about half of the rebar 2 cover so that it can be finished with one wet spraying it can. That is, since the spray thickness can be increased, the rebar 2
The surface can be covered, and in a particularly severe corrosive environment, the progress of corrosion of the rebar 2 and the adhesion and entrapment of chloride ions during restoration work can be significantly reduced.

[0013] The fast setting cement refers to a cement that sets faster than ordinary Portland cement, which is the most common cement used in reinforced concrete structures. Examples of the cement that quickly sets include early-strength Portland cement, ultra-fast-strength Portland cement, cement premixed with a quick setting agent, and quick-setting cements such as jet cement and alumina cement.

[0014] The powder containing the cement that rapidly sets is a solid material that can be pneumatically pumped among the materials used for spraying, and includes at least the cement that rapidly sets. Further, aggregates such as sand and various admixtures in powder form may be contained as necessary.

Next, a cement mortar having a high salt barrier property and resistant to cracking, or a mortar 4 containing fibers therein is wet-coated with a wet mortar 4 in a range of about 20 mm of the surface layer or about half the cover of the reinforcing bar 2. Finish by spraying or ironing. Sufficient resistance to chloride ions permeating from the outside can be provided by the wet spraying of the mortar.

Here, a cement mortar having a high salt barrier property and less likely to cause cracks is defined as a salt mortar and a crack when compared with ordinary Portland cement which is the most common cement used in reinforced concrete structures. It refers to a material that has improved the performance of at least one of the resistances and maintains both the salt barrier property and the crack resistance at least at the same level as ordinary Portland cement. Examples of the materials having enhanced salt barrier properties include a latent hydraulic material such as blast furnace slag, pozzolan such as fly ash and silica fume, a cement mortar containing a polymer, and a special cement mortar in which the amount of C ₃ A in the cement is increased. Cement mortar using cement is exemplified. Further, as one having improved crack resistance, cement mortar to which a shrinkage reducing agent and an expanding material are added is exemplified.

[0017]

According to the method for repairing a reinforced concrete member of the present invention described above, cement is sprayed at a high pressure by dry spraying on the uneven portion of the hung surface, and no voids remain. A large spray thickness can be applied in a short time, and in particularly severe corrosive environments, the progress of corrosion of rebar and the adhesion of chloride ions during construction can be significantly reduced, and the surface layer has high salt barrier properties and cracks occur. Difficult cement mortar finishes will have sufficient resistance to chloride ions penetrating from the outside.

Moreover, the repairing method of the present invention is an economical repairing method because the construction cost can be reduced because no formwork is used.

[Brief description of the drawings]

FIG. 1 is an image sectional view at the time of construction in one embodiment to which a repair method of the present invention is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Concrete 2 Reinforcing steel 3 Cement mortar which sets quickly 4 Cement mortar which has high salt barrier property and does not easily generate cracks

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Michio Muramatsu 5 Tobancho, Chiyoda-ku, Tokyo Toa Construction Industry Co., Ltd. (72) Inventor Toshikazu Minematsu 7-15-2 Tsudanuma, Narashino-shi, Chiba (72) Invention Person Kazuaki Akazawa 1 Familiar, Kanda Midoshiro-cho, Chiyoda-ku, Tokyo Sumitomo Osaka Cement Co., Ltd. F-term (reference) 2D059 BB39 GG21 GG40 2E176 AA01 BB01 BB15

Claims (1)

[Claims] Claims: 1. Concrete at a repaired portion of reinforced concrete is suspended up to the back surface of a reinforcing bar, and a powder containing cement, which rapidly sets, is pneumatically fed, mixed with water immediately before spraying, and sprayed to the repaired portion. A method for repairing a reinforced concrete member that has deteriorated due to salt damage by attaching a cement mortar that has high salt barrier properties and does not easily crack on the surface layer.