JP2009263739A - Electric corrosion protection method of reinforced concrete structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique of an electric corrosion protection of a reinforced concrete structure configured to increase adhesion force of the thermal spraying metal adhering to the surface of the concrete structure in an anodic protection system and configured to improve the durability of the thermal spraying metal. <P>SOLUTION: A reinforcing bar 16a is embedded within a reinforced concrete structure 16. The surface 16b of the reinforced concrete structure 16 is subjected to blasting treatment. A projecting part 16c and a recessed part 16d are formed on the surface 16b of the reinforced concrete structure 16 by performing the blasting treatment. A thermal spraying metallic layer 17 is formed on the surface 16b of the reinforced concrete structure 16 subjected to the blasting treatment. The thermal spraying metallic layer 17 is composed of an alloy of aluminum (Al), zinc (Zn), indium (In). A thermal spraying metal liquid is formed by performing thermal spraying under a prescribed wind pressure (kg/cm<SP>2</SP>) in such a manner that a mean coating thickness is about 300 (μm). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an electro-corrosion protection method for a reinforced concrete structure which is an galvanic anode method and is intended to increase the adhesion of the sprayed metal adhering to the surface of the concrete structure and to improve the durability of the sprayed metal. .

One example of this type of reinforced concrete structure in the anticorrosion method is disclosed in Japanese Patent Laid-Open No. 10-245280 shown in FIG.
Explaining this, the surface of the concrete structure 1 in which the reinforcing bars 2 are embedded as a reinforcing material is removed from the adhering material such as dust and oil as necessary, and then the primer is applied and dried to form the primer layer 3. To do. The primer is applied by a conventionally used coating means such as spray, and the application amount after drying is, for example, 10 to 300 g / m ² , preferably 20 to 150 g / m ² . Instead of blasting, a primer containing aggregates was applied to overcome this problem. On the primer layer 3 thus formed, two wires selected from zinc, aluminum and zinc-aluminum alloy wire are simultaneously sprayed to form a secondary coating composed of a zinc-aluminum pseudo-alloy spray coating. The electrode layer 4 is formed. Although the film thickness of the secondary electrode layer 4 of the zinc / aluminum pseudo-alloy spray coating formed on the primer layer 3 can be arbitrarily determined, it is usually 20 to 1000 (μm), particularly 30 to 200 ( μm). Next, a primary electrode layer 5 made of zinc, aluminum, magnesium, or an alloy thereof is at least partially formed on the secondary electrode layer 4. The primary electrode layer 5 may be applied to the entire surface of the secondary electrode layer 4, but the secondary electrode layer 4 made of a zinc / aluminum pseudo-alloy sprayed coating flows a stable and uniform anticorrosion current for a long period of time. Therefore, usually, the surface area of the primary electrode layer 5 is preferably 5 to 70 (%), particularly 10 to 50 (%) with respect to the total surface area of the secondary electrode layer 4. . The thickness of the primary electrode layer 5 is, for example, 300 to 10,000 (μm), particularly 500 to 5,000 (μm) in the case of a plate-like material, and in the case of a sprayed film, for example, 100-3,000 (micrometer), especially 120-1,000 (micrometer) are preferable. The secondary electrode layer 4 thus formed and the reinforcing bar 2 are connected by a conductive material 6 that is insulation-coated. As a result, the primary electrode layer 5 on the secondary electrode layer 4 functions as a primary electrode, that is, a galvanic anode, and is electrically decomposed and corroded instead of iron. As a result, the reinforcing bar 2 Is electrically anticorrosive.

As another example of the conventional technique, there is a technique of a metal spray coating method disclosed in Japanese Patent No. 2973449 shown in FIGS. 5 and 6.
To explain this, 7 is a molten metal supply system, 8 is a metal spray nozzle, 9 is a molten resin supply system, 10 is a resin injection nozzle, 11 is a base material, 12 is a spray metal, 13 is a coated metal layer, 14 is Molten resin, 15 is a sealing resin layer, A is a metal spray point, B is a resin spray point, and L is a separation distance between the metal spray point A and the resin spray point B. When the material of the base material 11 is, for example, carbon steel, the molten metal supply system 7 is applied to the metal spray nozzle 8 in a state where a coated metal material such as aluminum or zinc is dissolved as a metal capable of imparting corrosion resistance. It is supplied and ejected. The molten resin supply system 9 is supplied to the resin injection nozzle 10 in a state where the thermoplastic resin is dissolved, and is ejected onto the coated metal layer 13 shown in FIG. The sealing resin layer 15 is formed by adhering. Further, the separation distance between the metal spray point A and the resin ejection point B, that is, the separation distance L between the metal spray nozzle 8 and the resin injection nozzle 10 is appropriately set based on the temperature distribution of each part described later. Then, the temperature of the coated metal layer 13 gradually cools as it cools from the high temperature state, but when the molten resin 14 melted at a temperature similar to that during the cooling is deposited on the coated metal layer 13, Affinity arises and it becomes easy to enter into the space | gap P, and adhesive force will improve. Further, the opening of the gap P is closed by covering the coated metal layer 13 with the molten resin 14. And when cooling of the molten resin 14 progresses, the molten state of the molten resin 14 is maintained by delaying the temperature decrease on the inner side in contact with the coated metal layer 13. In addition, when the gas confined in the space between the metal particles of the coated metal layer 13 cools, the gas confined between the metal particles contracts and becomes a negative pressure state. The phenomenon of being taken into the void P of the metal particle occurs, and then, as the individualization phenomenon progresses with the cooling of the void P of the metal particle, it becomes individualized and remains sealed while intervening in the void P of the metal particle. The peel strength of the pore resin layer 15 is improved.
Japanese Patent Laid-Open No. 10-245280 Japanese Patent No. 2974349

Since the conventional technology has the above-described configuration, the following problems existed.
First, according to one example described above, it is porous immediately after spraying, and when it gets wet with seawater etc. before becoming dense by self-sealing, it penetrates into the inside and corrodes the sprayed coating to generate hydrogen gas. For this reason, it may be possible to improve the adhesion of the sprayed material by blasting the surface of the concrete structure, but this will deteriorate the working environment and surrounding environment due to the generation of dust, and the aggregate Unlike the blasting of the steel material surface, there is a problem that a sharp uneven surface cannot be obtained and adhesion cannot be obtained.
According to another example described above, the surface of the coated metal layer is in a porous state, so that a coating layer is applied and enters the void P of the metal particles, but complete sealing is obtained by the evaporation holes of the used organic solvent. There was a problem that it was difficult.

The anticorrosion method for a reinforced concrete structure according to the present invention has been invented to solve the above-mentioned problems, and is an galvanic anode method that increases the adhesion of sprayed metal sprayed on the surface of the concrete structure. The purpose is to improve the durability of the sprayed metal, and it consists of the following constitution and means.

That is, according to the first aspect of the invention, the thickness is 270 (μm) by spraying after blasting the surface of the reinforced concrete structure in the galvanic anode method in the cathodic protection method. A sprayed metal layer composed of an anode within a range of up to 330 (μm) is formed, and a synthetic resin material is applied and impregnated on the surface of the sprayed metal layer to form a synthetic resin layer.

According to the invention of claim 2, in the invention of claim 1, the sprayed metal layer is selected from aluminum (Al), zinc (Zn), indium (In), and magnesium (Mg). It is formed of one or more kinds of alloys.

According to a third aspect of the invention, in the first aspect of the invention, the synthetic resin layer comprises an acrylic emulsion resin material, an alkoxysilane resin material, a sodium silicate resin material, a siloxane resin material, and a solvent acrylic clear. It is characterized by being formed of one type of resin material selected from a resin resin material, an aqueous acrylic emulsion resin material, a silicone-modified urethane resin material, and a silane resin material.

Since the anticorrosion method for a reinforced concrete structure according to the present invention has the above-described configuration, it has the following effects.
That is, according to the first aspect of the invention, the thickness is 270 (μm) by spraying after blasting the surface of the reinforced concrete structure in the galvanic anode method in the cathodic protection method. A reinforced concrete structure characterized in that a sprayed metal layer comprising an anode within a range of up to 330 (μm) is formed, and a synthetic resin material is applied and impregnated on the surface of the sprayed metal layer to form a synthetic resin layer. Provide an anti-corrosion method.
With such a configuration, the sprayed metal layer increases the adhesion force to the surface of the reinforced concrete structure, and the anticorrosion current that is passed between the sprayed metal layer and the reinforcing bar is within the range of extending the life of the sprayed metal layer. It becomes possible to control the anticorrosion current over a long period of time.

According to the invention of claim 2, the sprayed metal layer is formed of one or more kinds of alloys selected from aluminum (Al), zinc (Zn), indium (In), and magnesium (Mg). The galvanic corrosion prevention method for a reinforced concrete structure according to claim 1 is provided.
Since this structure is adopted, in addition to the effect of the invention of claim 1, the sprayed metal layer is selected from general-purpose metals such as aluminum (Al), zinc (Zn), indium (In), and magnesium (Mg). One or more types of alloys can be used, which has the effect of facilitating implementation.

According to a third aspect of the present invention, the synthetic resin layer comprises an acrylic emulsion resin material, an alkoxysilane resin material, a sodium silicate resin material, a siloxane resin material, a solvent acrylic clear resin material, and an aqueous acrylic emulsion resin material. 2. The method for providing an anticorrosion method for a reinforced concrete structure according to claim 1, wherein the method is formed of one kind of resin material selected from silicone modified urethane resin material and silane resin material.
With such a configuration, in addition to the effect of the invention of claim 1, a synthetic resin material that can be impregnated up to the surface of the reinforced concrete structure is obtained, and the adhesion force of the sprayed metal layer is further increased.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments in an anticorrosion method for a reinforced concrete structure according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a vertical sectional view of a reinforced concrete structure according to the present invention. FIG. 2 is a drawing showing the type of synthetic resin applied to the surface of the sprayed metal layer formed on the reinforced concrete structure and the adhesion force (N / mm ² ) of the sprayed metal layer.

Reference numeral 16 denotes a reinforced concrete structure, in which a reinforcing bar 16a is embedded. The surface 16b of the reinforced concrete structure 16 is blasted. Here, the blast treatment is a processing method in which, for example, a powdered abrasive is collided to roughen the surface 16b of the reinforced concrete structure 16. By blasting in this way, the surface 16b of the reinforced concrete structure 16 is formed with a convex portion 16c and a concave portion 16d. Then, a sprayed metal layer 17 is formed on the surface 16b of the reinforced concrete structure 16 subjected to the blasting process. The sprayed metal layer 17 is made of, for example, one or more kinds of alloys selected from aluminum (Al), zinc (Zn), indium (In), and magnesium (Mg). The synthetic metal liquid is formed by thermal spraying at a predetermined wind pressure (kg / m ² ) so that the average coating thickness becomes about 300 (μm).

Next, for example, one of the resins shown in FIG. 2 is applied to the surface of the sprayed metal layer 17 to form the synthetic resin layer 18. Here, the cathodic protection method is divided into an external power supply method and a galvanic anode method depending on the method of supplying the galvanic protection current. It is a system in which it is installed in the vicinity and connected to a steel material to flow the anticorrosion current using the potential difference between the two to prevent corrosion. It is characterized by no need for power supply equipment. This method can be applied not only to existing reinforced concrete structures but also to PC structures and new structures for the purpose of preventive maintenance.

Here, before explaining the cathodic protection method according to the present invention, the phenomenon of corrosion of the reinforcing bars 16a in the reinforced concrete structure 16 will be described.
The rebar 16a as a steel material forms a so-called oxygen concentration cell when moisture comes in contact with the surface thereof, and the portion of the rebar 16a in contact with the central portion of the moisture having a low oxygen concentration forms an anode, and the moisture having a high oxygen concentration. The portion of the reinforcing bar 16a that is in contact with the peripheral portion forms a cathode (cathode). Due to this potential difference, a corrosion current flows in the reinforcing bar 16a, and the anode (anode) portion of the reinforcing bar 16a is corroded by the corrosion current.

Therefore, in the present invention, as shown in FIG. 1, first, a sprayed metal layer 17 made of an anode is formed on the surface 16 b of the reinforced concrete structure 16. The sprayed metal layer 17 is basically made of zinc (Zn) metal that is more easily ionized than the reinforcing bar 16a made of iron (Fe) in the ionization tendency. The reinforcing bar 16a is rusted is present condition water _(H 2 O) and oxygen _{(O 2),} internal and moisture from the outside of the reinforced concrete structures 16 _(H 2 O) and oxygen _{(O 2)} the ion It is easy to combine with zinc (Zn), which is easily formed.
The oxidation reaction occurring at the anode, that is, the anode reaction is (A) Fe → Fe ²⁺ + 2e ⁻
(B) Zn → Zn ²⁺ + 2e ⁻
However, since iron (Fe) and zinc (Zn) are connected, the reaction (B) occurs and the reaction (A) is suppressed. And corrosion of the reinforcing bar 16a is suppressed. Specifically, the reaction (B) occurs from the concrete surface of zinc (Zn), and 2e ⁻ flows toward the reinforcing bar 16a. The remaining zinc Zn ^{2+ combines} with a hydroxyl group to form another substance, namely Zn (OH) ₂ . That is, the sprayed metal layer 17 is more easily ionized than the reinforcing bar 16a and has a negative potential, and this acts as an anode when the reinforcing bar 16a is brought into contact. For this reason, when the reinforcing bar 16a serves as a cathode, a current flows from the sprayed metal layer 17 to the surface of the reinforcing bar 16a, and when this current is called an anticorrosion current and a current larger than the above-described corrosion current flows, the reinforcing bar 16a has a current as shown in FIG. Although the corrosion phenomenon can be prevented, if the anti-corrosion current is too large, the sprayed metal layer 17 formed of the anode is dissolved by itself to reduce the adhesion of the sprayed metal layer 17 and shorten the life of the sprayed metal layer 17. From the above, according to the present invention, as shown in FIG. 3, for example, if the life of the sprayed metal layer 17 is guaranteed for about 15 years, the anticorrosion current is controlled to a low value and the anticorrosion current density (mA / m ² ). Turned out to be set to about 5.0.

Next, procedures and actions based on the embodiment in the cathodic protection method for a reinforced concrete structure according to the present invention will be described.

As shown in FIG. 1, the surface 16b of the reinforced concrete structure 16 is subjected to blast surface treatment, for example, by causing a powdery abrasive or abrasive to collide with a predetermined air pressure (kg / m ² ) at a predetermined usage (kg / m ² ). I do. By the blast surface treatment, the surface 16b of the reinforced concrete structure 16 is roughened by forming a convex portion 16c and a concave portion 16d having an inner wall surface having a substantially spherical shape, for example. Then, using a thermal spraying device (not shown), for example, a metal solution composed of any one of aluminum (Al), zinc (Zn), indium (In), magnesium (Mg), or a synthetic metal thereof. Thermal spraying is performed on the surface 16b of the reinforced concrete structure 16 subjected to blast surface treatment with a predetermined wind pressure (kg / m ² ). As a result, the sprayed metal layer 17 having an average coating thickness of, for example, about 300 (μm) is formed. Next, using another coating means, the surface of the sprayed metal layer 17 is, for example, a synthetic resin material shown in FIG. 2, that is, an alkoxysilane resin material, an acrylic emulsion resin material, or a sodium silicate resin material or a siloxane resin material (not shown). The synthetic resin layer 18 is formed by applying and impregnating a solvent acrylic clear resin material, an aqueous acrylic emulsion resin material, a silicone-modified urethane resin material, and a silane resin material.

As time passes, the resin liquid 18 a droops and penetrates into the pores 17 a formed in advance on the sprayed metal layer 17 from the synthetic resin layer 18. As shown in FIG. 1, the resin liquid 18 a reaches the surface 16 b of the reinforced concrete structure 16, but does not hang down and penetrate all the pores 17 a formed in the sprayed metal layer 17. There is a non-penetrating part in a part. As a result, aluminum hydroxide is leached.

Thus, as time further elapses, the resin liquid 18a drooping and penetrating to the surface 16b of the reinforced concrete structure 16 is cured to form an insulator, and the adhesion force of the sprayed metal layer 17 to the surface 16b of the reinforced concrete structure 16 Will be granted. Therefore, it becomes difficult for the anticorrosion current to flow between the sprayed metal layer 17 and the reinforcing bar 16a to flow. And as mentioned above, the surface 16b of the reinforced concrete structure 16 is formed in the convex part 16c and the concave part 16d, and the blast surface treatment is carried out, and the dissolved particles are entangled by spraying a metal solution on the surface 16b. To form a film. This is a so-called throwing effect. The sprayed metal layer 17 is formed by this throwing effect.

It was confirmed that the adhesion force (N / mm ² ) was increased by setting the thickness of the sprayed metal layer 17 within the range of 270 (μm) to 330 (μm). As shown in the experimental data shown in FIG. 5, for example, when the thickness of the sprayed metal layer 17 is 300 (μm) formed by spraying, it is used for the synthetic resin layer 18 formed on the surface of the sprayed metal layer 17. According to its respective synthetic resin materials shown in 2 adhesion of the coating amount of 100 (g / mm ²⁾ from 150 (g / mm ²⁾ to the sprayed metal layer 17 as can be seen from FIG. 2 (N / mm ² ) Was 3.3 (N / mm ² ) to 4.8 (N / mm ² ), which was about 2.3 to 3.4 times higher than that of the unpainted case.

Thus, in the present invention, a suitable synthetic resin material in which the resin liquid 18a of the synthetic resin layer 18 hangs down and penetrates to the surface 16b of the reinforced concrete structure 16 from the pores 17a of the thermal spray metal layer 17 is selected, and the thermal spray metal layer 17 is The structure which secures the increase in the adhesive force to the surface 16b of the reinforced concrete structure 16 was devised. Further, the following became clear when the thickness of the above-mentioned sprayed metal layer 17 was less than 270 (μm) and when the thickness exceeded 330 (μm).

When the thickness of the sprayed metal layer 17 is less than 270 (μm), the sprayed metal layer 17 becomes an anode in the circuit of the battery due to the ionization tendency, and decreases with the passage of time. If the life of the cathodic protection is 15 years at (8 mA), it cannot be guaranteed below this value. When the thickness of the sprayed metal layer 17 exceeds 330 (μm), as shown in FIG. 1, the non-penetrating portion disappears and aluminum hydroxide cannot be leached. And since the leaching distance becomes long and the synthetic resin material cannot reach the surface 16a of the reinforced concrete structure 16, the adhesion force of the sprayed metal layer 17 is insufficient.
According to the experimental results, the adhesion of the sprayed metal layer 17 increases more rapidly as the amount of the resin liquid 18a forming the synthetic resin layer 18 increases, regardless of the number of the pores 17a formed in the sprayed metal layer 17. It turned out to increase.

On the other hand, when an experiment was conducted to further clarify the features of the present invention, as shown in FIG. 3, the durability, that is, the lifetime (year) and the anticorrosion current value of the sprayed metal layer 17, more specifically, the anticorrosion current density (mA / m ^2). ) Was obtained. According to the relational characteristic diagram, when the anticorrosion current density is high, the life of the sprayed metal layer 17 is set to be very short in 2 to 3 years and is inferior in durability, and the anticorrosion current density is 5.0 (mA / m When less than ² ), it has been found that the life of the sprayed metal layer 17 is 15 to 20 years and is set to a long time to improve the durability. From this, it is preferable to control the current density to 5.0 (mA / m ² ) when the lifetime of the sprayed metal layer 17 is considered to be 15 (years) from the relational characteristic diagram. The current density (mA / m ² ) can be controlled by controlling the replenishment of moisture from the outside. That is, what is necessary is just to determine how much the resin liquid 18a should be applied to the pores 17a of the sprayed metal layer 17.

It is a vertical sectional view of a reinforced concrete structure according to the present invention. It is drawing which shows the kind of synthetic resin apply | coated to the surface of the thermal spray metal layer formed in the reinforced concrete structure, and the adhesive force (N / mm < ² >) of a thermal spray metal layer. It is a relational characteristic figure of corrosion-proof current density (mA / m < ² >) with respect to the lifetime (year) of the thermal spray metal layer based on the reinforced concrete structure concerning this invention. It is a vertical sectional view showing an example in the prior art. It is an explanatory outline figure showing other examples in conventional technology. It is an expanded sectional view which shows the principal part of FIG.

Explanation of symbols

16 Reinforced concrete structure 16a Reinforcing bar 16b Reinforced concrete structure surface 16c Reinforced concrete structure surface convex part 16d Reinforced concrete structure surface concave part 17 Thermal spray metal layer 17a Thermal spray metal layer pore 18 Synthetic resin layer 18a Synthesis Resin layer resin liquid

Claims (3)

It is a galvanic anode method in the cathodic protection method, and the surface of a reinforced concrete structure is subjected to blasting and then sprayed to form an anode having a thickness in the range of 270 (μm) to 330 (μm). A cathodic protection method for a reinforced concrete structure, characterized in that a sprayed metal layer is formed, and a synthetic resin material is applied and impregnated on the surface of the sprayed metal layer to form a synthetic resin layer. 2. The reinforced concrete according to claim 1, wherein the sprayed metal layer is made of one or more alloys selected from aluminum (Al), zinc (Zn), indium (In), and magnesium (Mg). An anti-corrosion method for structures. The synthetic resin layer is an acrylic emulsion resin material, alkoxysilane resin material, sodium silicate resin material, siloxane resin material, solvent acrylic clear resin material, aqueous acrylic emulsion resin material, silicone-modified urethane resin material, silane resin 2. The method of cathodic protection of reinforced concrete structure according to claim 1, wherein the method is made of one resin material selected from resin materials.

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