JP2012144771A - Electric anticorrosion method for reinforced concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric anticorrosion method for a reinforced concrete structure, which can prevent reinforcing rods arranged in concrete from corroding too much in an external power source system by stabilizing electrical resistance rate of reinforced concrete, and which can prevent excessive consumption of the sacrificial anode in a galvanic anode system.SOLUTION: In the method, mud, dirt, dust and the like are removed from the surface where a surface impregnation material 7h is coated to make sure that the water content ratio of a coated surface is 8 (%) or less. Next, a standard coating amount e.g., 0.2 to 0.25 (kg/m) of the surface impregnation material 7h is coated once. After coating, the surface coated with the surface impregnation material 7h is cured for 48 hours and hardened in a state that it is not directly wetted by rainwater or the like. Then, by connecting the titanium ribbon mesh electrode as an anode material 7f to the anode side of the external power source and by connecting the stirrup iron rod, not shown in the figure, to the cathode side, an energization test or depolarization test is carried out to determine the appropriate energization amount.

Description

The present invention maintains the moisture content of the concrete constituting the frame in the reinforced concrete structure at a low and constant level and stabilizes the electrical resistivity of the concrete. The present invention relates to an anticorrosion method in a reinforced concrete structure that can prevent over-corrosion of the reinforcing bars arranged in the galvanized steel and prevents excessive consumption of the sacrificial anode in the galvanic anode method.

One example of this type of reinforced concrete structure in an anticorrosion method is disclosed in Japanese Patent Laid-Open No. 2006-23255 shown in FIG.
If it demonstrates about this, the surface coating | covering material 2 containing lithium salt will be uniformly apply | coated to the surface 1a of the concrete 1 of a reinforced concrete structure. For example, before the step of installing the anode 3 such as titanium mesh in the concrete, the surface treatment material 2 containing lithium salt is applied in advance to the concrete surface, so that the concrete 1 and the anode 3 such as titanium mesh are interposed between them. Water retention is imparted, thereby ensuring a uniform electrical conductivity.

In FIG. 7, the surface covering material 2 is schematically shown. Actually, when the surface covering material 2 is a lithium salt aqueous solution, the surface covering material 2 penetrates into the inside of the concrete 1 after being applied, and cement, resin, lithium In the case of a surface coating material of a cement-based composition containing salt, a layer of the cement-based composition is formed between the surface 1 a of the concrete 1 and the anode 3.

Examples of the surface treatment material 2 include an aqueous solution of a lithium salt, a cement, a lithium salt-containing cement-based composition containing a lithium salt, and a resin. The surface covering material 2 containing any lithium salt also increases the hygroscopicity of the surface 1a by application to the surface 1a of the concrete 1, resulting in a decrease in the volume resistance of the concrete surface and an improvement in electrical conductivity. As the lithium salt, hygroscopic lithium salts such as lithium hydroxide, lithium carbonate, lithium nitrite and lithium nitrate can be used, and these lithium salts can be used alone or in combination. Lithium nitrite can be suitably used from the viewpoint of the rust prevention effect by ions and the improvement of the strength of the cured product by capillary filling.

Further, by using a lithium salt having hygroscopicity, lithium ions are combined with moisture in the air, and the moisture in the air is collected, thereby increasing the water retention of the surface 1a of the concrete 1 and improving the conductivity. The effect that can be obtained.
In addition, 4 is a DC power supply device, and 5 is a reinforcing bar arranged in a reinforced concrete structure.

Japanese Patent Laid-Open No. 2006-232559

Since the conventional technology has the above-described configuration, the following problems existed.
In other words, the conventional external power source type cathodic protection method is to apply a lithium salt-based surface treatment material to and impregnate the concrete constituting the reinforced concrete structure prior to installing the anode material. The water retention between the anode material is improved, the electrical conductivity of the concrete is improved, and the anticorrosion current is secured. However, if moisture is supplied from the inside of the reinforced concrete structure or from the back side of the reinforced concrete structure, the electrical resistivity of the concrete changes and the distribution is not uniform. As a result, it is impossible to ensure a uniform electrical resistivity in the concrete, and particularly in areas where the moisture content is high, excessive current flows exceeding the appropriate current for electrocorrosion, resulting in overcorrosion. Let

In this overcorrosion state, the water in the concrete is electrolyzed and hydrogen is generated at the outer periphery of a steel material such as a reinforcing bar constituting the cathode. Most of the generated hydrogen is converted into hydrogen gas and released to the outside of the reinforced concrete structure, but some hydrogen penetrates and is absorbed by the reinforcing bars in the concrete, and the toughness and strength of the reinforcing bars are rapidly reduced. This phenomenon is called hydrogen embrittlement, and the higher the yield strength of the steel constituting the rebar, the more easily hydrogen embrittlement occurs and even a small amount of hydrogen causes brittle fracture, so over-corrosion of the rebar is prevented in reinforced concrete structures. Do not let it occur.

Therefore, pre-tensioned and post-tensioned PC concrete structures as reinforced concrete structures, such as main girders of bridges, are made of PC steel using high-strength steel, and a pre-tension load is applied to the PC steel. Therefore, it is difficult to apply a general cathodic protection method in order to avoid the risk of over-corrosion causing brittle fracture. In particular, it is difficult to apply to the PC concrete structure using PC steel an electro-corrosion-proof method that improves the water retention between the concrete and the anode material and easily causes over-corrosion as shown in the prior art. there were.

The anticorrosion method for a reinforced concrete structure according to the present invention has been invented to solve the above-mentioned problems, and has the following constitution and means.

That is, according to the invention described in claim 1, in the cathodic protection method for a reinforced concrete structure, the surface impregnating material containing any one of silane, siloxane and silane / siloxysan is provided on the concrete surface of the reinforced concrete structure. It is characterized by applying.

According to the second aspect of the present invention, in the first aspect of the present invention, the cathodic protection method for the reinforced concrete structure is formed with a groove between the concrete surface and the reinforcing bar, and a titanium ribbon mesh electrode (anode material) is provided. The external power supply system is characterized in that it is installed and the gap in the groove is filled with mortar or injection material.

According to a third aspect of the present invention, in the first aspect of the invention, the cathodic protection method for a reinforced concrete structure electrically connects a sacrificial anode material containing zinc at an appropriate interval to the exposed rebar. It is a buried sacrificial anode method.

Since the anticorrosion method in the reinforced concrete structure according to the present invention has the above-described configuration, the following effects are obtained.
That is, according to the invention described in claim 1, in the cathodic protection method for a reinforced concrete structure, the surface impregnating material containing any one of silane, siloxane and silane / siloxysan is provided on the concrete surface of the reinforced concrete structure. An anticorrosion method for a reinforced concrete structure is provided.
Because of this structure, it can prevent substances that corrode rebar such as salt water and rain water, especially acid rain, from entering the inside of the concrete, even when salt is mixed into the concrete as impurities during the manufacture of reinforced concrete structures. In the cathodic protection method, chlorine gas generated in the anode reaction and water vapor generated in the cathode reaction can be transmitted to the outside of the reinforced concrete structure through the surface impregnated material. The surface impregnating material can protect the surface of the reinforced concrete structure for a long time without destroying the surface, and the surface impregnating material covers the surface of the reinforced concrete structure, so the moisture content inside the reinforced concrete structure is low and Since it is held uniformly and stably, as a result, a uniform anti-corrosion current can be passed through the reinforcing bars. Corrosion prevention can be prevented, and over-corrosion does not occur, so the rebar does not cause hydrogen embrittlement and can maintain the reliability in the strength of reinforced concrete structures, especially PC concrete structures, and can maintain the strength for a long time. effective.

According to the second aspect of the present invention, the cathodic protection method for the reinforced concrete structure is such that a groove is formed between the surface of the concrete and the reinforcing bar, a titanium ribbon mesh electrode (anode material) is installed, and mortar or The external anti-corrosion method for a reinforced concrete structure according to claim 1, which is an external power supply system filled with an injection material.
Since it was set as such a structure, in addition to the effect of invention of Claim 1, a groove | channel is cut into the surface of the concrete in a reinforced concrete structure, and the linear titanium ribbon mesh electrode as an anode material is embed | buried. Thus, the cathodic protection method can be completed without causing a problem that the anode material causes a short circuit with the reinforcing bar as the cathode material, and there is an effect that construction reliability can be improved and labor can be saved.

According to the invention described in claim 3, the cathodic protection method for the reinforced concrete structure is a buried sacrificial anode system in which a zinc sacrificial anode material containing zinc at an appropriate interval to the exposed reinforcing bar is connected to the reinforcing bar. An anticorrosion method for a reinforced concrete structure according to claim 1 is provided.
Since it was set as such a structure, in addition to the effect of invention of Claim 1, since the surface impregnation material coat | covers the surface of the concrete in a reinforced concrete structure, the moisture content inside the concrete is made low and uniform. Since it can be held stably, the consumption of the sacrificial anode material containing zinc is suppressed, and replacement and expansion of the sacrificial anode material containing zinc is not required for a long period of time. There is an effect that management becomes easy.

It is a vertical sectional view of a reinforced concrete structure according to the present invention. FIG. 2 is a vertical sectional view showing details in part A of FIG. 1. FIG. 2 is a vertical sectional view showing that a silane-based surface impregnating material is applied to a concrete surface, the concrete is cut vertically, and the concrete surface is impregnated with the silane-based surface impregnating material. It is the perspective view which showed the state which uses for the external air exposure test the some concrete test body from which surface treatment conditions differ. It is a related characteristic figure of the weight change (g) of a concrete test piece with respect to an exposure period (week) as a result of having provided the several concrete test piece from which surface treatment conditions differ to an external air exposure test. BRIEF DESCRIPTION OF THE DRAWINGS It is a vertical sectional view of the reinforced concrete structure which shows the Example which concerns on this invention, Comprising: (a) is a partial vertical sectional view which shows the state which removed the concrete and exposed the reinforcing bar, and attached the sacrificial anode to this reinforcing bar (B) is the partial vertical sectional view which shows the state which apply | coated the surface impregnation material after refilling the reinforcing bar which attached the sacrificial anode with mortar. It is an explanatory outline figure of the cathodic protection method of a concrete structure in conventional technology.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of an anticorrosion construction method in a reinforced concrete structure according to the present invention will be described 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 vertical cross-sectional view showing details in part A of FIG.
A PC bridge 6 as a reinforced concrete structure is generally composed of a PC girder 7 and a ground cover 9, and the lower end surface of the PC girder 7 is installed on the upper end surface of an abutment (not shown). The span length of the PC bridge, that is, the distance between the abutment and the abutment is about 20 to 40 (m), and the length of the PC girder 7 in the bridge axis direction is also about 20 to 40 (m). The PC girder 7 is a post tension type PC girder. Inside the PC girder 7, reinforcing bars (not shown) are arranged in the whole area, and in particular, PC steel members 7b, 7b,... Covered with a plurality of sheaths 7a as shown in FIG. It is streaked. PC steel materials 7b, 7b ... are prestressed concrete, that is, members that apply compressive force to PC, PC steel wire, that is, high strength steel having a diameter of 8 (mm) or less, PC steel rod, that is, steel having a diameter of 10 (mm) or more. There are high-strength steel and high-strength stranded wire obtained by twisting PC steel stranded wire, that is, PC steel wire, and these are collectively referred to as PC steel. The material of the sheath 7a is a thin-walled steel pipe, and the PC steel materials 7b, 7b,... Are connected to a cathode of an external power source (not shown) via a stirrup rebar in an external power source type cathodic protection method. In addition, 7c is a grout injected and filled in the gap between the PC steel materials 7b, 7b,... And the sheath 7a, and the material of the grout 7c is a non-shrinkage cement paste or a nonshrinkage mortar.

7e is a groove formed on the surface of the concrete 7d by a tool such as a concrete cutter continuously in the bridge axis direction, and is processed in the vicinity of the sheath 7a and not penetrating to the sheath 7a.
Reference numeral 7f denotes an anode material embedded in the groove 7e, which is made of a titanium ribbon mesh and connected to the anode side of an external power source (not shown). 7g is a non-shrink mortar for fixing the titanium ribbon mesh electrode as the anode material 7f to the groove 7e. 7h is, for example, a one-component reactive silane-based surface impregnating material applied to the surface of the concrete 7d with a brush or a roller. The surface impregnating material 7h penetrates from the surface of the concrete 7d and prevents the concrete 7d from permeating and absorbing water. The surface impregnating material 7h may be a siloxane-based or silane-silane-siloxysan-based surface impregnated material in addition to the silane-based material.

Next, the characteristics of the one-component reactive silane-based surface impregnated material 7h will be described in detail with reference to FIGS.
FIG. 3 shows a vertical state in which a silane-based surface impregnating material 7h is applied to the surface of the concrete 7d, the concrete 7d is cut vertically, and the surface of the concrete 7d is impregnated with the silane-based surface impregnating material 7h. It is sectional drawing. As can be seen from FIG. 3, the surface impregnated material 7h is impregnated from the surface of the concrete 7d to a depth of 2 (mm) to 4 (mm).

FIG. 4 is a perspective view showing a state in which a concrete specimen 10 having a rectangular parallelepiped shape having a cross-sectional dimension of 100 (mm) × 100 (mm) and a length of 400 (mm) is subjected to an outside air exposure test. The six concrete specimens 10 were subjected to an outside air exposure test for about 14 weeks after giving the same three surface treatment conditions two by two prior to the start of the test. The three types of surface treatment conditions are as follows: untreated, that is, as it is in a concrete base, a silicate-based modifier applied to the concrete specimen 10 at a rate of 0.25 (kg / m ² ), and silane There are three types of the surface impregnated material 7h applied to the concrete specimen 10 at a rate of 0.25 (kg / m ² ). FIG. 5 shows the change in weight by measuring the weight of each of the six concrete specimens 10 every one to two weeks. Curves a and b in FIG. 5 represent changes in the weight of the untreated concrete specimen 10. Curves c and d in FIG. 5 represent changes in the weight of the concrete specimen 10 coated with the silicate-based modifier at a rate of 0.25 (kg / m ² ). Curves e and f in FIG. 5 represent changes in the weight of the concrete specimen 10 coated with the silane-based surface impregnating material 7h at a rate of 0.25 (kg / m ² ).

During the test period of about 14 weeks, there were three rains as shown in FIG. 5, and the six concrete specimens 10 were wet. As can be seen from FIG. 5, the untreated concrete specimen 10 and the concrete specimen 10 coated with a silicate-based modifier at a rate of 0.25 (kg / m ² ) absorbed rainwater when wet. When the weather is fine, the rainwater absorbed is discharged and dried to decrease the weight, and the moisture content inside the concrete specimen 10 is not stabilized. On the other hand, the concrete specimen 10 coated with the silane surface impregnating material 7h at a rate of 0.25 (kg / m ² ) is rainy regardless of the weather due to the water permeability and water absorption preventing action of the silane surface impregnating material 7h. Further, it can be understood that the weight always keeps a gradual decreasing tendency without absorbing rain water, and the amount of water in the concrete specimen 10 is stabilized while being reduced compared with the time of placing concrete.

The silane-based surface impregnating material 7h applied to the concrete 7d can prevent substances that corrode the reinforcing bars such as salt water and rain water, particularly acid rain, from entering the concrete 7d and has gas permeability. 6 Even when salt as an impurity adhering to fine aggregates is mixed into the concrete 7d when the PC girder 7 is manufactured, chlorine gas generated by the anode reaction and water vapor generated by the cathode reaction in the cathodic protection method are generated. The surface impregnating material 7h can be transmitted and diffused outside the PC beam 7.

Therefore, the chlorine gas or water vapor generated in the concrete 7d does not physically destroy the surface impregnating material 7h, and the surface impregnating material 7h can protect the surface of the concrete 7d over a long period of time. Since the surface of the concrete 7d is covered, the moisture content inside the concrete 7d is low and uniformly and stably maintained. As a result, a uniform anticorrosion current can be passed through the PC steel materials 7b, 7b.

Therefore, the PC steel materials 7b, 7b,... Do not cause over-corrosion prevention, so that the PC steel materials 7b, 7b,... Do not cause hydrogen embrittlement and maintain the reliability in the strength of the PC bridge 6. The strength can be maintained for a long time.
In addition, although PC steel materials 7b, 7b... Have been described as an example, the anticorrosion method in the reinforced concrete structure according to the present invention is not limited to the PC steel materials 7b, 7b. This also has the same effect on prevention of over-corrosion protection against reinforcing bars.

Next, the construction method, procedure, etc. of the embodiment of the anticorrosion method in the reinforced concrete structure according to the present invention will be described.
First, in a reinforced concrete structure for which an anticorrosion method is applied to a reinforced concrete structure, the inside of the concrete 7d is explored using an electromagnetic induction method or an X-ray exploration method, and the position of the sheath 7a, the reinforcing bar, or the concrete 7d The depth from the surface to the sheath 7a and the reinforcing bar, that is, the fog of the concrete 7d is measured. Then, using a tool such as a concrete cutter, a groove 7e of about 20 mm is processed from the surface of the concrete 7d, taking care not to damage or cut the sheath 7a or the reinforcing bar. A plurality of the grooves 7e are processed along the longitudinal direction of the sheath 7a and the reinforcing bar as shown in FIG. And after processing the groove | channel 7e, if foreign matters, such as a number wire, have exposed the groove | channel 7e, it will short-circuit with the titanium ribbon mesh electrode as the anode material 7f of a post process, and since a corrosion-proof electric current cannot be sent normally, It is confirmed that the foreign matter such as the wire and the titanium ribbon mesh electrode as the anode material 7f are not short-circuited.

Next, the groove 7e is covered with the tip of a titanium ribbon mesh electrode as the anode material 7f and filled with 7g of non-shrink mortar, and then the titanium ribbon mesh electrode as the anode material 7f is embedded in the non-shrink mortar 7g. . Further, the non-shrink mortar 7g is coated on the titanium ribbon mesh electrode as the anode material 7f so that the titanium ribbon mesh electrode as the anode material 7f is not exposed to the outside air. Then, curing is performed to cure 7 g of the non-shrink mortar.

Next, the application range of the silane surface impregnating material 7h in the reinforced concrete structure is determined.
The application range of the surface impregnating material 7h is intended for a portion that is easily wetted by rainfall or snowfall and that is difficult to dry due to retention of rain or snowfall. Specifically, as shown in FIG. 1, a surface impregnating material 7h is applied to the vertical surfaces of the lower portions 7C and 7D of the PC beam 7 and the left side 7E1 of the intermediate portion 7E of the PC beam 7.

In the coating range, the right side 7E2 of the middle part 7E of the PC girder 7 and the both sides 7F1 and 7F2 of the middle part 7F of the PC girder 7 are not coated. This is because there is nothing. Further, the surface impregnating material 7h is applied to the entire outer periphery of the lower portions 7C and 7D of the PC girder 7 when rainwater or snow blows up from below when the weather is strong or rainy. This is to prevent wetting of 7D. In some cases, the surface impregnating material 7h is applied to the lower surface and the side surface of the upper structure.

And the titanium ribbon mesh electrode as the anode material 7f is connected to the anode side of the external power source, and the PC steel materials 7b, 7b,... Start energization.
Thus, by cutting the groove 7e on the surface of the concrete 7d in the reinforced concrete structure and embedding a linear titanium ribbon mesh electrode as the anode material 7f, the anode material 7f is a PC steel material as a cathode material. It is possible to complete the anticorrosion method without causing a short circuit with 7b, 7b, etc., and to realize improvement in construction reliability and labor saving.

Next, the work procedure of the surface impregnating material 7h will be described.
First, mud, dust and the like adhering to the surface to which the surface impregnating material 7h is applied are removed with a disk sander, a wire brush, a non-woven fabric abrasive or the like. And the surface moisture content of the surface to apply | coat is measured and it is confirmed that the surface moisture content is 8 (%) or less. Next, the surface impregnating material 7h is applied once with a standard coating amount, for example, 0.2 to 0.25 (kg / m ² ) with a roller brush or the like. After coating, the coated surface of the surface impregnating material 7h is cured so that it is not directly wetted by rainwater or the like, and allowed to stand for 48 hours to be cured.
And the surface impregnating material 7h can prevent the substance that corrodes the PC steel materials 7b, 7b,... Such as rain or snow 11 containing salt water or acid from entering the concrete 7d. Even when salt is mixed into the concrete 7d as an impurity, chlorine gas generated by the anode reaction and water vapor generated by the cathode reaction in the cathodic protection method permeate through the surface impregnating material 7h and dissipate outside the PC girder 7. Therefore, the surface impregnating material 7h can protect the surface of the PC girder 7 over a long period of time without damaging the surface impregnating material 7h. Since the surface is covered, the moisture content inside the PC girder 7 is kept low and uniform and stable, and as a result, a uniform anticorrosive current can be passed through the PC steel materials 7b, 7b. Can prevent over-corrosion, and does not generate over-corrosion, so the PC steel materials 7b, 7b, etc. do not cause hydrogen embrittlement and maintain the reliability in the strength of the PC concrete structure and maintain the strength for a long time. It is possible to hold for a long time.

Next, an embodiment of the cathodic protection method in the reinforced concrete structure according to the present invention will be described with reference to FIG.
FIG. 6 is a vertical sectional view of a reinforced concrete structure showing an embodiment according to the present invention, in which (a) shows a state in which the reinforcing bar is exposed by removing the concrete and a sacrificial anode is attached to the reinforcing bar. A vertical sectional view, (b) is a vertical sectional view showing a state in which a reinforced reinforced reinforced bar is filled with a surface impregnating material.
Reference numeral 12 denotes, for example, a reinforced concrete girder on site that constitutes a reinforced concrete structure. The reinforced concrete girder 12 is laid in the horizontal direction of the reinforced concrete structure, is supported by an abutment and a pier (not shown), transmits the load on the floor, and mainly bears the load in the vertical direction. When a floor load is applied in the vertical direction together with its own weight, the reinforced concrete girder 12 is bent downward and is deformed so that the upper side is slightly shrunk and the lower side is extended. Since a concrete material is a brittle material, it can generally bear a compressive load, but cannot break a tensile load and breaks. Therefore, in the reinforced concrete girder 12, a number of reinforcing bars 13 as ductile materials are placed on the tension side, that is, the lower side, so that the reinforcing bars 13 are reinforced by bearing a tensile load to prevent the reinforced concrete girder 12 from being broken.

However, after the reinforced concrete girder 12 is placed, it is inevitable that fine cracks are generated particularly on the lower side of the reinforced concrete girder 12 due to a large fluctuating load such as an earthquake and drying shrinkage of the concrete material itself. When a fine crack occurs on the lower side of the reinforced concrete girder 12, rainwater or the like penetrates into the reinforced concrete girder 12 from the crack.

Since the cement constituting the reinforced concrete girder 12 exhibits alkalinity, the rebar 13 forms a thin film called a passive film on the surface of the rebar 13 in this alkaline environment, and the rebar 13 does not corrode. However, if chloride is present in the cement, the passive film is destroyed and corrosion of the rebar 13 proceeds. Corrosion-causing chlorides include incoming salt from the coast and antifreezing agents from the road surface. If these penetrate into the cracks on the lower side of the reinforced concrete girder 12 and exist around the reinforcing bars 13, the reinforcing bars 13 undergo corrosion. Further, when fine sand aggregate, that is, sand used for placing reinforced concrete girders 12, sea sand is used, and if the salt content of the sea sand is insufficient, the reinforced concrete girders 12 may be cracked. The chloride breaks the passive film of the reinforcing bar 13 by the moisture contained in the reinforcing bar 13, and the reinforcing bar 13 is corroded.

When the passive film of the reinforcing bar 13 is destroyed, a low potential portion, that is, an anode portion and a high potential portion, that is, a cathode portion are generated in the reinforcing bar 13 and a chemical reaction occurs to form a local corrosion battery. The ferric hydroxide generated in the portion of the corrosion cell changes to rust and the volume expands 2 to 4 times. Due to the expansion pressure due to the volume expansion, cracks occur in the reinforced concrete girder 12 around the rebar 13 and abnormalities such as peeling of the surface of the reinforced concrete girder 12 occur.

Denoted at 14 is a chipped portion where the surface of the reinforced concrete girder 12 in which an abnormality such as the surface is peeled off has been artificially removed by a chipping operation. Reference numeral 15 denotes a sacrificial anode material containing zinc. Reference numeral 16 denotes a wire for electrically connecting the sacrificial anode material 15 to the reinforcing bar 13.
When the sacrificial anode material 15 is connected to the reinforcing bar 13 via the wire 16, the zinc is Zn → Zn ²⁺ + 2e ⁻ based on the potential difference generated between the iron of the reinforcing bar 13 and the zinc of the sacrificial anode material 15.
It dissolves in the moisture contained in the reinforced concrete beam 12 by the reaction shown in FIG. Electrons (2e ⁻ ) generated at this time are attracted to the cathode portion at a high potential of the reinforcing bar 13 to lower the potential of the cathode portion. If the supply of the electrons (2e ⁻ ) is sufficient, the potential difference between the cathode and anode of the reinforcing bar 13 disappears and corrosion of the reinforcing bar 13 stops.

Reference numeral 17 denotes a non-shrinking mortar for covering the reinforcing bar 13 and the sacrificial anode material 15 after connecting the sacrificial anode material 15 to the reinforcing bar 13 and blocking it from the outside air. A silane-based surface impregnating material 18 is applied and impregnated after the non-shrink mortar 17 is cured. The surface impregnating material 18 may be a siloxane-based or silane-silane siloxysan-based surface impregnated material in addition to the silane-based material.

Next, the construction method, the procedure, etc. will be described with respect to an embodiment of the cathodic protection method in the reinforced concrete structure according to the present invention.
First, the reinforced concrete girder 12 in which an abnormality such as the surface peeling occurs has such an abnormality because the surface peeling or cracking in the vicinity where the reinforcing bar 13 is embedded and the discoloration of the reinforcing bar 13 due to rust water are remarkable. At the site, perform a chiseling operation to remove the concrete. This chipping work is performed on the concrete around the reinforcing bar 13 and the back side of the reinforcing bar 13 until the healthy part without rusting is exposed on the reinforcing bar 13, and the reinforcing bar 13 without rusting is exposed from the concrete by 50 mm or more. Do until you do. And the part which winds the wire 16 which connected the sacrificial anode material 15 in the whole exposed rebar 13 is completely rusted and polished until a metal bar of the rebar 13 is obtained with sandpaper or the like.

When the polishing of the reinforcing bar 13 is completed, the sacrificial anode material 15 is quickly electrically connected to the reinforcing bar 13 by the wire 16. Then, a probe such as a circuit tester is brought into contact with the reinforcing bar 13 and the wire 16 to confirm that the electrical resistance of the connecting portion between the reinforcing bar 13 and the wire 16 is a specified value of the sacrificial anode material 15, for example, 0.3 ohms or less. As shown in FIG. 6, a plurality of sacrificial anode materials 15 are connected to the reinforcing bars 13, and the usage amount of the sacrificial anode materials 15 is appropriately determined according to the amount of reinforcing bars 13. When all the sacrificial anode materials 15 are connected to the reinforcing bars 13, water is sufficiently sprayed on the reinforcing bars 13 to which the sacrificial anode materials 15 are connected and the surrounding concrete. Then, the non-shrink mortar 17 is backfilled as shown in FIG. After curing and curing the non-shrink mortar 17, it is confirmed that the surface moisture content of the non-shrink mortar 17 is 8 (%) or less. Then, the surface impregnation material 7h is applied once with a standard application amount, for example, 0.2 to 0.25 (kg / m ² ) with a roller brush or the like. After coating, the coated surface of the surface impregnating material 7h is cured so that it is not directly wetted by rainwater or the like, and allowed to stand for 48 hours to be cured.
Thus, since the surface impregnating material 7h covers the surface of the reinforced concrete girder 12, the moisture content inside the reinforced concrete girder 12 can be kept low and uniformly stable, so that the sacrificial anode material 15 is excessively large. Consumption is suppressed, replacement and expansion of the sacrificial anode material 15 is unnecessary for a long period of time, and maintenance and management related to the anticorrosion of the reinforced concrete girder 12 can be facilitated.

The present invention can be applied to reinforced concrete structures such as road bridges and PC concrete structures.

6 PC Bridge
7 PC digit 7C PC digit 7 lower part 7D PC digit 7 lower part 7E PC digit 7 middle part 7E1 PC digit 7 middle part left 7E2 PC digit 7 middle part right 7F PC digit 7 middle part 7F1 PC digit 7F2 left middle 7G2 right middle 7G PC 7 upper 7G PC 7 upper 7H PC 7 upper 7a sheath 7b PC steel 7c grout 7d concrete 7e groove 7f anode material (titanium ribbon mesh electrode)
7g Non-shrink mortar 7h Surface impregnating material 9 Ground cover 10 Concrete specimen 10
11 Rain or Snow 12 Reinforced concrete girder 13 Reinforcing bar 14 Detachment 15 Sacrificial anode material 16 Wire 17 Non-shrink mortar 18 Surface impregnated material

Claims (3)

In a reinforced concrete structure, a surface impregnating material containing any one of silane, siloxane, and silane / siloxysan is applied to the concrete surface of the reinforced concrete structure in an anticorrosion method for the reinforced concrete structure. An anti-corrosion method. The cathodic protection method for the reinforced concrete structure is an external power supply system in which a groove is formed between the concrete surface and the reinforcing bar, a titanium ribbon mesh electrode (anode material) is installed, and the gap in the groove is filled with mortar or injection material. The cathodic protection method for a reinforced concrete structure according to claim 1. 2. The reinforced concrete according to claim 1, wherein the cathodic protection method for the reinforced concrete structure is a buried reinforced concrete sacrificial anode method in which a sacrificial anode material containing zinc is connected to the exposed reinforcing bar at an appropriate interval. A cathodic protection method for structures.

Images