JP2594488B2 - Corrosion protection method for reinforced concrete structures - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for protecting a reinforced concrete structure from corrosion, and more particularly to a method for protecting a reinforced concrete structure from corrosion. This is a method of preventing corrosion of a reinforced concrete structure that can be provided.

[0002]

2. Description of the Related Art Reinforcing bars are usually embedded in concrete structures for reinforcement. However, this rebar
Corrosion occurs due to the neutralization of concrete or the effect of salt contained in the concrete material, and chloride ions and sulfate ions contained in the water that enters the concrete. Rebar has the disadvantage that its function as a reinforcing material is lost in a relatively short time. Therefore, conventionally, in order to prevent corrosion of reinforcing steel, (a) a method of applying an anticorrosion paint to the surface of a concrete structure, (b) a method of electrolytic protection using an external power supply method, and (c) an electrolytic protection method using a galvanic anode method. A method was used. However, in the method (a) of coating the anticorrosion paint on the surface of the concrete structure, the physical strength of the coating film formed by the anticorrosion paint is not sufficiently strong, so that the coating film is easily damaged. There is a drawback that the corrosion factor is inferior to long-term corrosion protection because the corrosion factor invades from the part.
In addition, (b) the method of electrolytic protection using an external power
Excellent long-term corrosion protection, but requires special equipment such as power supply and monitoring equipment, and requires regular management, so running costs such as equipment costs, electricity costs and labor costs There was a drawback that it took. On the other hand, (c) the cathodic protection method using the galvanic anode method has attracted attention because it does not require special equipment, is easy to maintain, and has excellent long-term corrosion protection. I have.

[0003] Typical examples of the galvanic anode method include (i) a groove burying method, (ii) a groove burying and covering method, (iii) a zinc plate mounting method, and (iv) a galvanic anode member mounting method. Although these methods are known, any of these methods has a drawback that it is difficult to work on a vertical surface, a ceiling surface, a place having a complicated shape or a narrow place, and the workability is poor. Furthermore, (i) the kerf embedding method has a drawback that it is difficult to obtain a sufficient anticorrosion current because the surface area of the zinc ribbon is insufficient, and (ii) the kerf burying method has a conductive polymer cement mortar or the like. Disadvantageous in that the adhesion between the conductive secondary electrode and the concrete substrate and / or the zinc ribbon tends to decrease, causing blistering and peeling of the conductive secondary electrode, making it difficult to flow a uniform anticorrosion current for a long period of time. (Iii) The zinc plate mounting method has the disadvantage that the adhesion of the mortar coated on the zinc plate is insufficient, and when repairs are performed, the work becomes large-scale. ) The method of mounting the galvanic anode member has a disadvantage in operation that it is difficult on site to cut or attach the galvanic anode member to the dimensions of the concrete structure.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to an anticorrosion method for a reinforced concrete structure capable of imparting excellent anticorrosion properties over a long period of time with good workability even on a complicated shaped portion, a vertical surface, a ceiling surface, etc. of the reinforced concrete structure. The aim is to provide a method.

[0005]

Means for Solving the Problems The present inventors have studied the problems of such a galvanic anode system, and have taken advantage of the characteristics of the galvanic protection method using the galvanic anode system, while also having excellent workability. The present invention has been completed as a result of research for developing a long-term anticorrosion method for a structure. Therefore, the present invention forms a primer layer having a rough surface by applying a primer containing an aggregate to the surface of a reinforced concrete structure, and sprays a metal having a greater ionization tendency than iron on the primer layer. The present invention provides a method for preventing corrosion of a reinforced concrete structure, characterized in that a sprayed coating layer is formed by the above method, and the sprayed coating layer and the reinforcing steel are connected with a conductive material.

Hereinafter, the present invention will be described in detail. The primer used in the present invention contains an aggregate and a binder as essential components, and further contains a solvent (or a dispersion medium), a pigment, and various additives as necessary. The aggregate used in the present invention has an average particle size of about 10 to 200 μm,
The thickness is preferably 30 to 100 μm and can form sharp irregularities on the surface of the primer layer. Examples of the aggregate of the present invention include metals and alloys having the same ionization tendency as the metal to be sprayed, various metals and alloys having at least a surface insulated, and oxides thereof (for example, aluminum oxide and iron oxide). ), Nitrides, carbides, etc., as well as silicon oxide, silicon carbide,
Examples thereof include boron nitride and a plastic powder that does not dissolve in the solvent in the primer. The amount of the aggregate is about 30 to 300% by volume, preferably 65 to 15% by volume, based on the binder.
0% by volume, about 25-75% as a pigment volume concentration (PVC),
Preferably, 40 to 60% is appropriate. Due to the aggregate contained in the primer, the surface of the primer layer formed on the concrete structure has a moderate surface roughness, preferably JIS B-0601
The surface roughness (Rz) specified in can be about 40 to 150 μm, and this surface roughness enables the formation of a sprayed coating with excellent adhesion on the surface of reinforced concrete structures without blasting. it can.

[0007] As the binder used in the present invention, conventional binders for paints can be used without particular limitation as long as they are excellent in drying property, water resistance, adhesion and the like, and examples thereof include: , Chlorinated rubber, alkyd resin, one-pack normally dry resin such as vinyl resin, epoxy resin, unsaturated polyester resin, acryl-urethane resin, polyester-
Two-part curable resin such as urethane resin (used together with a curing agent)
In the present invention, a two-pack type epoxy resin having particularly good water resistance and adhesion is preferable. Examples of the solvent (or dispersion medium) to be added as necessary include ordinary organic solvents for coatings such as xylene, toluene, butanol, methyl ethyl ketone, and butyl acetate, and water, and examples thereof include pigments. Is an extender such as barium sulfate, calcium carbonate, and talc; and a coloring pigment such as titanium oxide and carbon black.Examples of the additives include an antifoaming agent, an anti-sagging agent,
And dispersants. Solvent 0 to primer weight
It is preferred to add 50% by weight and 0 to 30% by weight of pigment. The primer used for coating may be of any form such as an organic solvent type, an aqueous type or a liquid solventless type.

The metal spray-coated on the primer layer in the present invention is not particularly limited as long as it has a higher ionization tendency than iron. Commonly used metals include zinc, zinc alloys, aluminum, aluminum alloys, copper,
There are copper alloys and the like. Here, the zinc alloy refers to an alloy obtained by mixing at least one kind of metal such as Al, Cu, Mg, Fe, etc., with Zn as a main component.
An alloy containing Al as a main component and containing at least one kind of metal such as Zn, Mg, Cr, and Si, and a copper alloy is a copper alloy containing Cu as a main component and containing Ni, Zn, Sn, and Al. Means an alloy obtained by mixing at least one metal. Further, in the present invention, it is preferable to form the thermal spray coating layer using a Zn-Al pseudo alloy having a Zn / Al ratio of 90/10 to 50/50 (weight ratio). The reason is that the thermal sprayed coating layer formed of the Zn—Al pseudo alloy has excellent anticorrosion properties, has a large cohesive breaking force, is dense, and hardly generates blisters. The Zn-Al pseudo alloy refers to a state in which zinc and aluminum do not form an alloy structure, and zinc fine particles and aluminum fine particles are irregularly overlapped to form a Zn-Al alloy in appearance. This Zn—Al pseudo alloy coating can be formed by using a spray wire of zinc and aluminum and performing arc spraying by a low-temperature spraying method such as an arc spraying method under reduced pressure.

FIG. 1 is a characteristic partial sectional side view of a typical reinforced concrete structure subjected to anticorrosion treatment by the method of the present invention. Based on this figure, a method of preventing corrosion of a reinforced concrete structure of the present invention will be described. I do. The surface of the concrete structure 1 in which the reinforcing bar 2 is embedded as a reinforcing material is subjected to removal of extraneous matter such as dust and oil, if necessary, and then the primer is applied and dried to form a primer layer 3.
The application of the primer is performed by a conventionally used coating means such as a spray, a brush or a roller, and the applied amount is adjusted to about 20 to 400 g / m ² , preferably 40 to 200 g / m ² . Conventionally, in order to improve the adhesion of the metal spray coating, a method of blasting the surface of the substrate to be sprayed and roughening the surface has been generally used. If applied to the surface, dust will be generated, deteriorating the working environment and surrounding environment, and the surface hardness of concrete structures will be lower than that of steel, etc., and concrete aggregates will fall off the surface. It is difficult to obtain a sharp uneven surface with sharp angles as in the case of blasting, and as a result, there was a problem that a thermal sprayed coating having excellent adhesion could not be formed.However, the present invention, instead of performing the blasting method, This problem was overcome by applying a primer containing aggregate.

The semi-dried or completely dried primer layer 3 thus obtained is sprayed with a metal having a higher ionization tendency than that of iron, that is, a metal which is electrically decomposed and corroded in place of iron. 4 is formed. Examples of a method for spraying metal include a gas flame spraying method, an electric arc spraying method, and a low-temperature spraying method using an arc spraying machine under reduced pressure. In the present invention, any method may be used. If the temperature of the sprayed metal particles is high, the primer layer may be burned out, or if the Zn-Al pseudo-alloy is formed, JP-B-47-24859, JP-A-61-167472, etc. The low-temperature thermal spraying method using an arc spraying machine under reduced pressure disclosed in U.S. Pat. The low-temperature thermal spraying method using the arc sprayer in the reduced pressure utilizes a low-temperature air flow that is injected cylindrically,
Under the environment where the central part is depressurized from the peripheral part, the metal wire is continuously and electrically arc-melted, and simultaneously sucked into the forward jet stream, pulverized, rapidly cooled, and in a liquid supercooled state And spraying the sprayed metal particles on the primer layer.

The thickness of the thermal spray coating layer formed on the primer layer is about 100 to 3000 μm, preferably 130 to 1000 μm. By connecting the thermal spray coating layer 4 thus formed and the reinforcing bar 2 with a conductive material 5 whose surface is insulated and coated, the thermal spray coating layer 4 functions as a galvanic anode, and the reinforcing bar 2 is electrically protected. It is done. The conductive material used in the present invention is not particularly limited as long as it connects the conductive material 5 and the reinforcing bar 2 in a state where electricity can move, and a lead wire or the like may be used. it can. The method for preventing corrosion of a reinforced concrete structure according to the present invention is as described above.In order to prevent the sprayed coating layer from being consumed by rust, a generally known anticorrosive paint is further applied on the sprayed coating layer to prevent the sprayed coating layer from being consumed by rust. You may. The method of the present invention comprises:
Although it can be applied to all concrete structures using steel frames, it is particularly suitable for concrete structures such as seaside structures, bridges and tunnels, which are highly corrosive.

[0012]

According to the method of the present invention, a metal sprayed coating having excellent workability and excellent adhesion can be formed even on a vertical surface, a ceiling surface, and a portion having a complicated shape of a reinforced concrete structure.
Therefore, a reinforced concrete structure excellent in long-term corrosion protection by the galvanic protection method of the galvanic anode method can be obtained. In addition, since a rough surface is formed on the surface of the reinforced concrete structure by applying a primer, it is not necessary to roughen the surface of the reinforced concrete structure by a blast treatment that is usually performed before spraying as in the past, and it is generated by blasting. It is possible to obtain the effect that the environmental pollution due to dust can be prevented and the operation time can be greatly reduced.

[0013]

The present invention will be described in more detail with reference to the following examples. <Primer> Epoxy resin [Epiclon 4051: trade name of Dainippon Ink and Chemicals, Inc .: epoxy equivalent 950] 10
To 0 g, 80 g of xylene, 60 g of methyl ethyl ketone, and 25 g of butanol were added and dissolved. A polyamide resin (Epicure 892: Celanese product name: active hydrogen equivalent: 133)
275 g (resin solid content capacity: 100 cm ³ ) of an epoxy-polyamide resin with a heating residue of 40% to which 10 g was added, and an average particle size of 48
μm silicon carbide (green silicon carbide CG320: Nagoya Abrasive Equipment Co., Ltd. product name: specific gravity 3.16) 221 g (particle capacity 70 cm
³ , 41% of PVC) was sufficiently stirred to prepare a primer. <Reinforced concrete test specimen>
Reinforced concrete specimen (100m)
m × 100 mm × 400 mm). The concrete is usually Portland cement, water / cement =
60/40 (weight ratio), sand / concrete aggregate = 54/46 (weight ratio), and a unit cement amount of 320 kg / m ³ . Further, in order to suppress the influence of the edge effect, a part of the end surface and the side surface other than the anode surface (the surface on which the thermal spray coating or the zinc ribbon is applied) was applied with a solventless epoxy resin paint and sealed.

[Example 1] The surface of a reinforced concrete specimen was washed with high-pressure water and cleaned, and then a primer was applied by air spray to 50 g / m ² and air-dried for 2 hours.
A primer layer having a surface roughness (Rz) of 60 μm was formed. Next, a flame spraying machine (manufactured by Meteco Co., Ltd.)
TYPE11E), spray zinc wire, 130μm thick
Was formed. The sprayed coating was connected to a lead wire attached to the end of the reinforcing bar to form an anode. Example 2 A zinc-aluminum alloy [Zn / Al = 72/28 (weight ratio)] was used instead of a zinc wire, except that a wire was used.
A primer layer and a sprayed coating layer were formed on the surface of the reinforced concrete test specimen in the same manner as in Example 1, and the sprayed coating was connected to a lead wire attached to the end of the reinforcing bar to form an anode. Example 3 After a primer layer was formed in the same manner as in Example 1, a zinc-aluminum pseudo alloy was formed on the primer layer using an arc spraying machine under reduced pressure (PA-100 manufactured by Pan Art Craft Co., Ltd.). Zn / Al = 72/28 (weight ratio)]
A sprayed coating layer having a thickness of 30 μm was formed, and the sprayed coating was connected to a lead wire attached to the end of a reinforcing bar to form an anode. The spraying was performed by using a zinc wire and an aluminum wire having a diameter of 1.3 mm at a carrying speed of 4 m / min, a voltage of 14 V, a current of 100 A, and an air pressure of 5 kg / cm.
^2. Low-temperature spraying was performed under the conditions of an air flow rate of 1 m ³ / min and a spray distance of 20 cm.

Comparative Example 1 A sprayed coating layer was formed on the surface of a reinforced concrete specimen in the same manner as in Example 1 except that the surface of the reinforced concrete specimen was roughened by sandblasting instead of forming a primer layer on the surface. The sprayed coating was connected to a lead wire attached to an end of a reinforcing bar to form an anode. [Comparative Example 2] A thermal spray coating layer was formed on the surface of a reinforced concrete specimen in the same manner as in Example 2 except that the surface was roughened by sandblasting instead of forming a primer layer on the surface of the reinforced concrete specimen. The coating was connected to a lead wire attached to the end of the reinforcing bar, and used as an anode.

Comparative Example 3 A groove 1 of depth × width = 10 mm × 10 mm was provided in the center of the surface of a reinforced concrete specimen in the length direction, and a 5 mm square zinc ribbon was embedded therein, and the ribbon was inserted into the end of the reinforcing bar. Connect to the attached lead wire to form an anode, and then apply a conductive polymer cement mortar containing carbon fiber to the surface of the reinforced concrete specimen so as to cover the ribbon.
It was applied so as to have a thickness of 15 mm, and a test piece of a kerf burying and covering method was produced. The test pieces obtained in Examples 1 to 3 and Comparative Examples 1 to 3 and the untreated test pieces were subjected to a salt spray test (with a salt water concentration of 5) in a test apparatus at 35 ° C. based on JIS Z 2371.
%) Immediately after the start of the test, 500 hours later, 1500 hours later,
After 3000 hours and 5000 hours after, potential measurement (using a saturated ampoule electrode), current density measurement (using a small ammeter), adhesion strength measurement (using an elcometer), and appearance observation were performed. The results are shown in Table 1. Was. As is clear from Table 1, Examples 1 to 3 in which corrosion was prevented by the method of the present invention were not only good in workability but also substantially the same as Comparative Example 3 in comparison with Comparative Example 3 in which the conventional method was used to bury and cover the kerf. Or better than that,
Furthermore, the adhesive strength and appearance of the anode are excellent, especially zinc-
Example 3 in which an aluminum pseudoalloy was formed had excellent performance. In addition, Comparative Examples 1 and 2 subjected to the blast treatment were inferior in adhesion to Examples 1 to 3.

[0017]

[Table 1] [Table 1] Example Comparison Potential measurement (unit: mV) 1 2 3 1 2 3 Immediately after starting the untreated test -623 -529 -562 -635 -510 -664 -165 500 hours (H) -979 -966 -996 -994 -934 -989 -575 1500H -750 -930 -951 -548 -903 -957 -566 3000H -650 -660 -925 -601 -600 -630 -552 5000H -610 -620- 902 -605 -575 -510 -535 Current density measurement (unit: mA / m ² ) Immediately after starting the test 20.5 20.5 21.0 19.5 22.5 17.0 − 500H 8.0 20.0 18.5 8.0 20.5 8.5 − 1500H 7.0 11.5 10.5 3.0 11.0 8.0 − 3000H 3.5 4.0 9.0 1.5 2.0 3.0 − 5000H 1.0 1.5 8.5 0.5 0.5 1.0 − Adhesion strength measurement (unit kgf / cm ² ) Immediately after the start of the test 27 29 27 19 18 17 − 500H 24 26 26 12 18 14 − 1500H 25 26 27 9 13 14 − 3000H 22 27 27 8 10 6-5000H 18 25 26 5 7 5- Appearance 500H Abnormal Same as left Same as left Same as left Same as left Same as left None 1500H Abnormal Same as left Same as left Same as left Same as left Same as left None 3000H Thermal spray film Abnormal Same as left Thermal spray film Sprayed film Mortar cracking, approx. 10% None Approx. 30% Approx. 10% Some blisters, rust juice disappears disappears disappears cracks occur 5000H sprayed film sprayed film abnormal sprayed film sprayed film mortar remarkable about 30% about 10% none about 70% about 30% whole face blisters, cracks, disappearance disappearance disappearance disappearance rust rust Outbreak

[0018]

[Brief description of the drawings]

FIG. 1 is a partial side sectional view of a reinforced concrete structure subjected to anticorrosion treatment by the method of the present invention.

[Description of Signs] 1 Concrete structure 2 Reinforcing bar 3 Primer layer 4 Thermal spray coating layer 5 Conductive material

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-266750 (JP, A) JP-A-64-62537 (JP, A) JP-A-3-2433783 (JP, A) JP-A-4- 297643 (JP, A) JP-A-3-174379 (JP, A) JP-A-3-100258 (JP, A)

Claims (2)

(57) [Claims] 1. A method for forming a primer layer having a rough surface by applying a primer containing an aggregate to a surface of a reinforced concrete structure, and spraying a metal having a higher ionization tendency than iron on the primer layer. A method for preventing corrosion of a reinforced concrete structure, comprising: forming a thermal sprayed coating layer on a substrate; and connecting the thermal sprayed coating layer and the reinforcing steel with a conductive material. 2. The method for preventing corrosion of a reinforced concrete structure according to claim 1, wherein the thermal spray coating layer formed on the primer layer is a layer made of a Zn—Al pseudo alloy.