JP6482969B2 - Section repair method for concrete structures - Google Patents

Description

  The present invention relates to a cross-section repair method mainly used in the field of civil engineering and construction, which protects steel materials such as reinforcing bars in concrete of a concrete structure for a long period of time from corrosion. The present invention relates to a cross-sectional repair method for preventing corrosion of a steel material inside a concrete by disposing a low metal as a sacrificial electrode and electrically connecting the steel material and the sacrificial electrode.

  In concrete structures, steel materials are embedded in the concrete structure, and concrete and steel materials are united and take on external forces. However, early deterioration is currently a problem.

  Degradation factors of concrete structures include salt damage, neutralization, frost damage, alkali aggregate reaction, chemical concrete corrosion, etc., as a selectable repair method for these deteriorations, cross-section repair method, surface protection method, Examples include a crack repair method, a salt removal method, and an alkali re-granting method.

  As a repair method for concrete structures deteriorated due to salt damage or the like, a cross-section repair method is generally widely used.

The cross-section restoration method is a method of removing concrete that has deteriorated in a concrete structure and filling the removed portion with a material having high durability against deterioration, such as polymer cement mortar, or a cross-section restoration material.
However, in the reinforcing bar penetrating the joint interface between the cross-section repair material and the concrete hardened body, the density of the deterioration factor is varied on the same reinforcing bar surface. For example, salt damage causes a difference in the amount of chloride ions, and neutralization causes a difference in pH. If there is a difference in the concentration of these deterioration factors on the same reinforcing bar surface, it is known that macrocell corrosion occurs mainly on the reinforcing bar surface near the joint interface on the hardened concrete side. It may deteriorate again in a few years.

  In other words, rebar macrocell corrosion occurs when the amount of deterioration factor is partially different on the same surface of successive rebars, and between the anode part (corrosion part) and the cathode part (non-corrosion part) at a distant position. This is a phenomenon in which the macrocell current flows and the anode part corrodes.

For this reason, in the civil engineering / architecture field, a method of preventing macrocell corrosion by installing a sacrificial anode material made of a metal having a higher ionization tendency than iron as an anode material in a cross-sectional repair portion is known (Patent Document 1). To Patent Document 8).
However, the conventional method is based on the premise that the sacrificial anode material is embedded in the cross-sectional repair material, and most of the anticorrosion current flowing from the sacrificial anode material flows into the reinforcing bar inside the cross-section repair material, and is most susceptible to macrocell corrosion. The corrosion prevention current was not efficiently supplied to the reinforcing bars on the side of the hardened concrete near the joint interface. In addition, it is difficult to replace the sacrificial anode material, which has been consumed and the anticorrosion effect is no longer observed, and it is difficult to apply when long-term durability is intended.

Japanese Patent No. 5388435 Japanese Patent No. 4801051 Japanese Patent No. 5437004 Japanese Patent No. 5613024 Japanese Patent No. 4091953 Japanese Patent No. 4648389 Japanese Patent No. 4574013 Japanese Patent No. 3099830

  As a result of diligent efforts, the inventor has solved the problems of the prior art by using specific materials and specific construction methods, preventing macrocell corrosion of rebars, which is a concern during the construction of cross-section repair methods, and sacrificing. The present invention was completed by obtaining knowledge that the anode material 4 can be easily replaced and that the optimum effect can be obtained in the cross-sectional repair method considering long-term durability.

The present invention employs the following means in order to solve the above problems.
(1) Sacrificial anode material composed of zinc or zinc alloy anode material 3 and a backfill material containing an electrolyte solution having a pH sufficient to avoid generation of anode passivation around anode material 3 4 is a method for repairing the cross section of a reinforced concrete structure in which the reinforcing bar 4 is installed on the surface of the hardened concrete body 2 and the reinforcing bar 1 and the sacrificial anode material 4 inside the hardened concrete body 2 are electrically connected. The position of the end portion 5 on the joining interface side of the anode material 3 is on the joining interface 7 between the cross-section repair material 6 and the concrete hardened body 2 or the surface of the hardened concrete body 2 within 30 cm from the joining interface 7. This is a method of repairing the cross section of a reinforced concrete structure in which the sacrificial anode material 4 is installed.
(2) The position of the joining interface side end portion 5 of the anode material 3 inside the sacrificial anode 4 is on the joining interface 7 or the surface of the hardened concrete body 2 within 30 cm from the joining interface 7. In the cross-sectional repair method of (1), the sacrificial anode material 4 is installed, and the sacrificial anode material 4 is further installed at an arbitrary position on the surface of the hardened concrete body 2.
(3) The cross-sectional repair method according to (1) or (2) above, wherein the sacrificial anode material 4 is wrapped with a sacrificial anode material covering material 8.
(4) The cross-sectional repair method of (3) above, wherein the sacrificial anode material covering material 8 has a specific resistance of 1 to 300 kΩ · cm.
(5) The cross-sectional repair method according to (3) or (4), wherein 50 to 500 g of organic-inorganic composite emulsion is applied to the surface of the sacrificial anode material coating material 8 per 1 m ² .
(6) The cross-sectional repair method according to any one of (3) to (5), wherein a permanent mold is installed on the surface of the sacrificial anode material covering material 8.
(7) The cross-sectional repair method according to any one of (1) to (6), wherein the conductive wire that electrically connects the reinforcing bar 1 and the sacrificial anode material 4 is replaceable.
(8) The sacrificial anode material covering material 8 contains a calcium aluminate compound having a CaO / Al ₂ O ₃ molar ratio of 0.15 to 0.7 and a Blaine specific surface area value of 2,000 to 7,000 cm ² / g. It is the cross-sectional repair method of any of (7).

  The cross-section repairing method of the present invention prevents macrocell corrosion of the reinforcing bar 1 which becomes a problem when the cross-sectional repairing method is performed, and also allows the replacement of the sacrificial anode material 4 to be easily performed, taking into account long-term durability. This is a restoration method.

FIG. 1 is a cross-sectional view of an internally installed specimen in which a sacrificial anode material 4 is installed inside a cross-sectional repair material 6.

FIG. 2 is a cross-sectional view of an externally installed specimen in which the sacrificial anode material 4 is installed on the surface of the hardened concrete body 2.

The present invention will be described in detail below.
Parts and% used in the present invention are based on mass unless otherwise specified.
The concrete referred to in the present invention is a generic term for cement paste, cement mortar, and cement concrete.

  In the present invention, the reinforcing bar 1 inside the hardened concrete body 2 is used as a cathode, the sacrificial anode material 4 is installed on the surface of the hardened concrete body 2 as an anode, and the two are electrically connected to each other, thereby preventing the anticorrosion current from being applied to the reinforcing bar 1. To reinforce the rebar 1.

  The sacrificial anode material 4 is a kind used in the electrochemical corrosion protection method, but does not require adjustment of the amount of current or maintenance of the external power supply, reduces the burden of maintenance after installation, and is subject to salt damage. The durability can be improved by using together with the cross-sectional repair method.

Here, the anode material 3 refers to a material that contains a metal that has a higher ionization tendency than iron and that prevents corrosion of the reinforcing bar 1 by ionization prior to iron.
Examples of the metal constituting the anode material 3 include zinc or zinc aluminum and / or magnesium alloy. In the present invention, zinc is used as the anode material 3 for ease of use.

  In order to avoid passivation of the anode material 3, it is necessary to maintain a sufficient pH around the anode material 3 with a backfill material (not shown). For example, when the anode material 3 is zinc or a zinc-aluminum alloy, the pH value is preferably 13.3 or higher, and the pH value for suppressing passivation is different depending on the metal used, but the pH value is usually 12 That's it.

  Since the pH of the electrolyte solution contained in the backfill material provided around the anode material 3 is high, there is a concern about the alkali silica reaction in the concrete portion where the backfill material such as cement mortar comes into contact. Therefore, it is preferable that an alkali silica reaction inhibitor is present in the electrolyte solution.

  As the alkali silica reaction inhibitor, lithium ions are preferable in order to avoid a decrease in pH of the electrolyte solution, and lithium hydroxide, lithium carbonate, or lithium type zeolite is preferably used.

  In the present invention, the method of electrically connecting the reinforcing bar 1 inside the hardened concrete body 2 and the sacrificial anode material 4 is as long as the reinforcing bar 1 and the metal constituting the sacrificial anode material 4 are electrically connected. Well, although not particularly limited, a method of embedding the end of a metal wire such as iron in the metal in the sacrificial anode material 4 and winding it around the reinforcing bar 1 is practically simple.

  In the present invention, the sacrificial anode material 4 was produced by covering the surface of the anode material 3 with a backfill material such as cement mortar containing an electrolyte solution having a pH sufficient to avoid the formation of a passive film. After removing the deteriorated portion of the hardened concrete body 2, the conductor is electrically connected to the reinforcing bar 1 inside the hardened concrete body 2, and the cross-sectional repair material 6 is placed. The sacrificial anode material 4 is placed so that the position of the end portion 5 on the joining interface side of the material 3 is the surface of the cured concrete body 2 within a range of 30 cm from the joining interface 7 of the hardened concrete body 2 and the cross-section repair material 6 Installed by wrapping with a sacrificial anode material covering material 8 such as cement mortar, and electrically connecting the sacrificial anode material 4 and the conductive wire, or the inside of the cross-section repaired portion in which the anode material 3 and the cross-section repair material 6 are placed Electrical connection of rebar 1 and anode material 3 is covered with a backfill material to form a sacrificial anode material 4, and the sacrificial anode material 4 is encased in mortar, etc., so that the position of the end portion 5 on the joining interface side of the anode material 3 and the concrete hardened body 2 are repaired Corrosion protection between the sacrificial anode material 4 and the reinforcing bar 1 inside the hardened concrete body 2 by installing the sacrificial anode material 4 so that the surface of the hardened concrete body 2 is within 30 cm from the joint interface 7 of the material 6. An electric current flows and the rebar 1 inside the hardened concrete body 2 is protected from corrosion.

In the present invention, the anticorrosion effect of the reinforcing bar 1 can be confirmed by measuring the potential.
When a metal having a lower standard electrode potential is electrically connected to the reinforcing bar 1 inside the hardened concrete body 2, the potential of the reinforcing bar 1 itself is lowered. Therefore, by measuring the potential, it is possible to determine the effectiveness of rebar corrosion protection from the numerical value.

  The potential is measured by using one point on the surface of the hardened concrete body 2 with the smaller reinforcing steel cover as a measurement point, for example, using a collation electrode using saturated copper sulfate. At this time, the sacrificial anode material 4 and the reinforcing bar 1 can be disconnected, and the instant-off potential (Eio potential) immediately after the disconnection and the potential after 24 hours (off-potential after 24 hours, Eof potential) And the repolarization amount is calculated from these differences. The greater the depolarization amount, the greater the effect of preventing the rebar 1 from being corroded. In general, the rebar 1 inside the hardened concrete body 2 is said to have achieved anticorrosion if a depolarization amount of 100 mV or more is obtained.

In the present invention, by defining the installation position of the sacrificial anode material 4 set on the surface of the hardened concrete body 2, the effect of preventing the macrocell corrosion of the reinforcing bar 1 is enhanced. Specifically, the position of the joining interface side end portion 5 of the anode material 3 inside the sacrificial anode material 4 is on the joining interface 7 of the cross-section repair material 6 and the hardened concrete body 2 or the cross-section repair material 6 and the concrete. The shortest distance from the joining interface 7 of the cured body 2 to the joining interface side end 5 of the anode material 3 included in the sacrificial anode material 4 is within 30 cm, and the joining interface side end 5 of the anode material 3 is. It is preferable to install the sacrificial anode material 4 so that the position of the surface of the hardened concrete body 2 is within 10 cm from the joint interface 7. If all or part of the sacrificial anode material 4 is within this range, the effect of preventing the macrocell corrosion of the predetermined reinforcing bar 1 can be obtained. However, when the sacrificial anode material 4 is installed outside this range, the joining interface In some cases, the effect of preventing macrocell corrosion that occurs in the reinforcing bar 1 on the side of the hardened concrete body from 7 cannot be obtained.
Since the reinforcing bar 1 is disposed inside the hardened concrete body 2, the sacrificial anode material 4 is disposed within the above range, and further, the sacrificial anode material 4 is disposed on an arbitrary surface of the hardened concrete body 2. preferable. Even if it is not installed directly above the reinforcing bar 1 inside the hardened concrete body 2, electricity flows between the reinforcing bar 1 inside the hardened concrete body 2 and the sacrificial anode material 4, which is effective.

In the present invention, the sacrificial anode material 4 is preferably wrapped with the sacrificial anode material covering material 8 when the sacrificial anode material 4 is installed on the surface of the concrete hardened body 2.
The material used for the sacrificial anode material covering material 8 is not particularly limited as long as the specific resistance described later is satisfied, but cement mortar is preferable.

  As the cement mortar of the material used for the sacrificial anode material covering material 8, various portland cements such as ordinary, early strength, ultra-early strength, low heat, and moderate heat, and blast furnace slag and fly ash are used. , Or various mixed cements mixed with silica, filler cement mixed with limestone powder, blast furnace slow-cooled slag fine powder, etc., and environmentally friendly cement (eco-cement manufactured using municipal waste incineration ash and sewage sludge incineration ash as raw materials Portland cement such as) can be used, and one or more of these can be used.

  The specific resistance of the sacrificial anode material covering material 8 is that the anticorrosion current from the sacrificial anode material 4 is not supplied excessively, durability can be expected, and the amount of anticorrosion current necessary for preventing macrocell corrosion can be supplied. 1 to 300 kΩ · cm is preferable, and 10 to 100 kΩ · cm is more preferable.

  In the present invention, it is possible to apply an organic-inorganic composite type coating curing agent to the surface of the sacrificial anode material covering material 8 enclosing the sacrificial anode material 4.

  The organic-inorganic composite type coating curing agent of the present invention is composed of a synthetic resin aqueous dispersion, a water-soluble resin, and a swellable clay mineral, and these and a crosslinking agent as main components.

Here, the synthetic resin aqueous dispersion is generally a synthetic resin emulsion, and includes an aromatic vinyl monomer, an aliphatic conjugated diene monomer, an ethylenically unsaturated fatty acid monomer, and other co-polymers. It is obtained by emulsion polymerization of one or two or more of polymerizable monomers. For example, styrene / butadiene latex mainly composed of styrene, styrene / acrylic emulsion, methyl methacrylate / butadiene latex copolymerized with styrene, and ethylene / acrylic emulsion.
The synthetic resin emulsion is more preferably one having a carboxyl group or a hydroxy group.
Here, the emulsion polymerization is a general emulsion polymerization method in which a monomer to be polymerized is mixed, and an emulsifier, a polymerization initiator, etc. are added to the monomer and the reaction is carried out in an aqueous system.
In order to obtain blending stability with the swellable clay mineral, it is preferable to use a basic substance such as ammonia, amines, and caustic soda and adjust the pH to 5 or more.
The particle diameter of the synthetic resin aqueous dispersion is generally 100 to 300 nm, but preferably has a small particle diameter of about 60 to 100 nm.

Examples of water-soluble resins include modified starch or derivatives thereof, cellulose derivatives, saponified polyvinyl acetate or derivatives thereof, polymers having sulfonic acid groups or salts thereof, polymers or copolymers of acrylic acid or salts thereof, Examples include acrylamide polymers and copolymers, polyethylene glycol, and oxazoline group-containing polymers, and one or more of them can be used. The water-soluble resin may be one having a solubility in pure water of 1% or more at room temperature, and preferably has 10 to 60% of hydrogen bonding groups or ionic groups per unit weight of the resin.
The average molecular weight is preferably 2,000 to 1,000,000.
The amount of the water-soluble resin used is preferably 0.05 to 200 parts in terms of solid content with respect to 100 parts of solid content of the synthetic resin aqueous dispersion.

Examples of swellable clay minerals include layered silicate minerals belonging to the scumite genus. For example, beidellite, nontronite, saponite, fluorine mica, bentonite and the like can be mentioned. Any of natural products, synthetic products, and processed products can be used. Of these, clay minerals having a swelling power of 20 ml / g or more measured by a method according to the Japan Bentonite Industry Association, standard test method JBAS-104-77, particularly fluorine mica and bentonite are preferred. The ion exchange equivalent of the swellable clay mineral is preferably 10 milliequivalents or more per 100 g. Furthermore, it is preferable that the swellable clay mineral has an aspect ratio of 50 to 5,000.
The aspect ratio is, for example, the ratio of the length / thickness of clay mineral particles dispersed in a layer shape obtained by an electron micrograph or the like.
The amount of the swellable clay mineral used is preferably 1 to 50 parts in terms of solid content with respect to 100 parts of solid content of the synthetic resin aqueous dispersion.

The cross-linking agent reacts with a hydrophilic functional group such as a carboxyl group, an amide group, and a hydroxyl group of a synthetic resin aqueous dispersion or water-soluble resin to crosslink, polymerize (three-dimensional network structure), or hydrophobic Those having an oxazoline group that undergoes an addition reaction with a carboxyl group also serve as a water-soluble resin, and are preferable.
The amount of the crosslinking agent used is preferably 0.01 to 30 parts in terms of solid content with respect to 100 parts of the total solid content of the synthetic resin aqueous dispersion and the water-soluble resin.

In the present invention, an organic-inorganic composite type coating curing agent is prepared by mixing an aqueous synthetic resin dispersion, a water-soluble resin, and a swellable clay mineral, and further reacting these with a crosslinking agent. .
As a method for synthesizing the organic-inorganic composite-type coating curing agent, a method in which a water-soluble resin and a swellable clay mineral are mixed in water in advance and then a synthetic resin aqueous dispersion and a crosslinking agent are mixed.
The organic-inorganic composite-type film curing agent coating method is not particularly limited as long as it can form a uniform curing coating film, and can be distributed, applied, or sprayed. Is possible. The organic-inorganic composite-type film curing agent is preferably applied to the surface after the setting of the cross-sectional repair material 6 is completed. For example, when the time elapses from several hours to several days, the surface of the mortar is dried and cracks are likely to occur. As such an organic-inorganic composite type film curing agent, “RIS full coat” or “Krakoff” manufactured by Denki Kagaku Kogyo Co., Ltd., “CA2” series manufactured by Toagosei Co., Ltd., or the like can be used.

In the present invention, the organic-inorganic composite type coating film curing agent is applied to the surface of the sacrificial anode material covering material 8 to further reduce the rate of change in length and suppress cracking, but also in the long term. The electric resistance of the cured body 2 can be kept constant and the anticorrosion effect can be enhanced.
The amount of the organic-inorganic composite-type coating curing agent used is not particularly limited, but is preferably 50 to 500 g per 1 m ^{2 of} cement mortar from the viewpoint of sufficient effect of keeping the electrical resistance small for a long period of time. 150 to 300 g is more preferable.

  In the present invention, by providing a permanent mold on the surface of the sacrificial anode material covering material 8, the anticorrosion effect is further enhanced.

Permanent formwork is a formwork that can be used as a part of a structure without being removed from the surface of the concrete structure even after placement, during construction work. This corresponds to the mold used when the anode material covering material 8 is coated.
By making the surface of the sacrificial anode material covering material 8 a permanent formwork, the formwork can suppress the diffusion of moisture from the sacrificial anode material covering material 8, and the effect of keeping the specific resistance of the mortar constant over the long term can be expected. .

  Any existing material can be used as long as it can be used for the formwork. However, since metals such as iron plates can be corroded, plastic materials are preferable, and materials with high weather resistance such as fluororesin and vinyl chloride are preferred. Is more preferable.

  In the present invention, the durability can be enhanced by mixing a calcium aluminate compound in the sacrificial anode material covering material 8.

A calcium aluminate compound (hereinafter referred to as a CA compound) is a CaO obtained by mixing a raw material containing calcia and a raw material containing alumina, etc., and performing a heat treatment such as firing in a kiln or melting in an electric furnace. And Al ₂ O ₃ as a main component.
In the present invention, the chemical composition of the CA compound is in the range of 0.15 to 0.7 in terms of the CaO / Al ₂ O ₃ molar ratio. Even if the CA compound contains, for example, SiO ₂ or R ₂ O (R is an alkali metal), it can be used as long as the object of the present invention is not impaired.
The CaO / Al ₂ O ₃ molar ratio of the CA compound of the present invention is preferably from 0.15 to 0.7, preferably from 0.45 to 0.6, in terms of sufficiently obtaining a chloride ion shielding effect and ensuring rapid hardening and pot life. Is more preferable.
The fineness of the CA compound of the present invention is from 2,000 to 2,000 in terms of a specific surface area value of brain (hereinafter referred to as “brane value”), from which a sufficient effect of shielding chloride ions can be obtained, and of rapid hardening and pot life. 7,000cm ² / g are preferred, 3,000~6,000cm ² / g is more preferable.
Further, the amount of the CA compound to be mixed is preferably 2 to 20 parts, more preferably 5 to 10 parts with respect to 100 parts of cement.

  The commercially available wire connected to the reinforcing bar 1 and sacrificial anode material 4 used in the present invention can be used, but considering the long-term durability, the coating material is highly durable such as fluororesin or polyethylene. Is preferred. Moreover, what attaches a connector etc. and becomes a structure with easy replacement | exchange is preferable.

  The cross-section repair material 6 used in the present invention is not particularly limited as long as it can be used for cross-section repair, and any existing one can be used, but considering long-term durability and integrity with the hardened concrete body 2. A polymer cement mortar mixed with an appropriate amount of the polymer for cement admixture is preferable.

  Hereinafter, the contents of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Experimental example 1
As shown in FIGS. 1 and 2, a 100 × 100 × 1,000 mm specimen was prepared by simulating partial cross-section repair and transferring the cross-section repair material 6 to the hardened cement concrete 2 as shown in FIGS. . The specimen preparation was performed in a constant temperature room at 20 ° C.
Ten split reinforcing bars 1 are arranged inside, and the split reinforcing bars 1 and the end of the specimen are filled with epoxy resin 11 and electrically insulated. The 10 split rebars 1 with a length of 75 mm are rebar No. 1, rebar No. 2, rebar No. 3, ... rebar No. 10 from the cross-section repair material 6 side, and the split rebar spacing is 20 mm. . It is possible to clarify the corrosion prevention range of the sacrificial anode material 4 by performing electrochemical measurement on each divided reinforcing bar 1.
The internal installation specimen in FIG. 1 is demolded the next day after placing concrete, and a sacrificial anode material 4 is installed on the end of the hardened concrete body 2 (on the reinforcing bar No. 1). A cross-sectional repair material 6 was placed so as to cover the surface. The joint interface 7 between the hardened concrete body 2 and the cross-section repair material 6 is subjected to roughening treatment with sand paper No. 60, and then only the water is moistened without using a primer. Then, an internally installed specimen in which the sacrificial anode material 4 was disposed inside the cross-sectional repair material 6 was produced.
Further, for the externally installed specimen in which the sacrificial anode material 4 shown in FIG. 2 is arranged outside the hardened concrete body 2, a cross-sectional repair material 6 is placed on the end of the hardened concrete body 2 and 10 × 10 × 1,000 mm The sacrificial anode material 4 was placed immediately above the cover side of electrode No. 2 on the next day. The size of the sacrificial anode material covering material 8 coated on the sacrificial anode material 4 was a cylindrical shape having a diameter of 9 cm and a height of 5 cm, and the sacrificial anode material 4 was disposed in the center. The sacrificial anode material 4 has a joining interface side end portion 5 of the anode material 3 included in the sacrificial anode material 4 directly above the reinforcing bar No. 2, that is, on the surface of the hardened concrete body 2 away from the joining interface by 3 cn. It installed so that it might come.
The joint interface 7 between the hardened concrete body 2 and the cross-section repair material 6 is roughened with a sandpaper No. 60, and then the primer is not used and only the water is dampened. Set up. Dry curing was performed in a 20 ° C room for 28 days from the preparation of the specimen. During the curing period, the split reinforcing bars 1 were electrically connected (A2 to A10 in FIGS. 1 and 2 were connected), but the sacrificial anode material 4 and the reinforcing bars 1 were not connected. After the curing is completed, the sacrificial anode material 4 and the reinforcing bar 1 are connected (connecting A1 in FIGS. 1 and 2), and then the specimen is left in a constant temperature and humidity room at 35 ° C. and 90% RH. The potential measurement test was started.
There were two types of concrete blending: compressive strength 24 N / mm ² shown in Table 1 and 40 N / mm ² , which is the strength normally specified for PC structures. The amount of chloride ion to be mixed was 10 kg / m ^3, and the reagent NaCl was mixed in an external ratio. The target slump was 12 ± 2.5 cm.

The potential was measured every 12 months from the start of the test. In preparation for potential measurement, a wet towel was applied to the specimen the day before, and the concrete at the measurement position was sufficiently moistened.
In the measurement of the potential, the reference electrode is pressed at the position of the measurement point 9 of the potential / polarization resistance value indicated by ★ shown in FIGS. 1 and 2, and the potential of the reinforcing bar 1 or the sacrificial anode material 4 inside the hardened cement concrete 2 is measured. Measurement was performed in a voltage measurement mode of a digital multimeter. The digital multimeter used has a voltage resolution of 0.1 mV and an accuracy of ± 0.5%. A saturated copper sulfate electrode (CSE electrode) was used as a reference electrode. The potential is the Eon potential with the sacrificial anode material 4 and the rebar 1 connected, the Eio potential immediately after the sacrificial anode material 4 and the rebar 1 are cut, and 24 after the sacrificial anode material 4 and the rebar 1 are cut. The Eof potential after the time was measured, and the difference between the Eio potential and the Eof potential was calculated as the depolarization amount. The test result was evaluated by the reinforcing bar number where the depolarization amount was 100 mV at 12 months. The results are shown in Table 2.

<Materials used>
Cement (C): Ordinary Portland cement, commercially available, density 3.15 g / cm ³
Fine aggregate (S): River sand from Himekawa, Niigata Prefecture, density 2.62g / cm ³
Coarse aggregate (G): Crushed stone from Himekawa, Niigata Prefecture, Gmax 15 mm, density 2.66 g / cm ³
Admixture (Add): Melamine sulfonate-based high-performance water reducing agent
NaCl: Reagent grade 1 sacrificial anode material α: Conducting a disk-shaped zinc block with a diameter of 3.9cm x height of 0.7cm with two mild steel wires, mortar with a sand / cement ratio of 3/1 and a water / cement ratio of 60% The kneaded water is a saturated lithium hydroxide aqueous solution, covered with a backfill material whose mortar pH is always 13 or more, and a cylindrical shape with a diameter of 6 cm and a height of 3.5 cm. Sacrificial anode Material covering material A: Mortar using ordinary cement with sand / cement ratio = 1/1 and water / cement ratio = 60%, with a specific resistance of 20 kΩ · cm at the age of 28 days. Acrylic ester (PAE) polymer cement mortar with polymer / cement ratio (P / C) = 5% and water / cement ratio (W / C) = 45%

Experimental example 2
In the externally installed specimen using a concrete composition having a compressive strength of 21 N / mm ^{2 in} Experimental Example 1, the position of the end 5 of the joining interface side of the anode material 3 included in the sacrificial anode material 4 is set to the hardened concrete body 2. Except that it is -5cm, 0cm, 3cm, 10cm, 20cm, 30cm, and 35cm from the joint interface 7 to the concrete restoration section 6 and the cross-section repair material 6, it is the same as the experiment using the externally installed specimen in Experimental Example 1 Went to.
Further, the sacrificial anode material 4 was changed and the installation position of the joining interface side end portion 5 of the anode material 3 was set to 10 cm from the joining interface 7 and the same experiment was performed. The results are shown in Table 3.

<Materials used>
Sacrificial anode material β: 90 parts of zinc metal and 10 parts of aluminum metal are mixed and put in a crucible heated to about 700 ° C, melted, diameter 3.9cm x height 0.7cm A disk-shaped mortar with a sand / cement ratio = 3/1 and a water / cement ratio = 60%. The kneading water uses a saturated lithium hydroxide aqueous solution, and the pH inside the mortar is always 13 or more. A sacrificial anode material γ: 90 parts of zinc powder and 10 parts of magnesium powder were added and coated with a backfill material that was made into a cylindrical shape with a diameter of 6 cm and a height of 3.5 cm The crucible was put in an electric furnace heated to about 700 ° C, melted, and formed into a disk shape with a diameter of 3.9cm x height of 0.7cm. Sand / cement ratio = 3/1 and water / cement ratio = 60% For the mixing water, use saturated lithium hydroxide aqueous solution, and the pH inside the mortar is always 1 Covered with 3 or more backfill material, 6cm in diameter x 3.5cm in height

Experimental example 3
In the externally installed specimen using a concrete composition with a compressive strength of 21 N / mm ^{2 in} Experimental Example 1, the sacrificial anode material 4 is placed at a position other than directly above the electrode No. ² to connect the sacrificial anode materials 4 to each other. The experiment was performed in the same manner as in the experiment using the externally installed specimen of Experimental Example 1, except that the connection was electrically made with a conducting wire. The results are shown in Table 4.

Experimental Example 4
Sacrificial anode covering material 8 in which the water / cement ratio was changed and the specific resistance was changed depending on the presence or absence of carbon fiber was used in the externally installed specimen using a concrete composition having a compressive strength of 21 N / mm ^{2 in} Experimental Example 1. Except for the above, the experiment was performed in the same manner as the experiment using the externally installed specimen of Experimental Example 1. The results are shown in Table 5.

<Materials used>
Sacrificial anode material coating material B: Mortar using ordinary cement with sand / cement ratio = 1/1, water / cement ratio = 70%, carbon fiber is mixed, and specific resistance at 28 days of age is 0.1kΩ · cm Sacrificial anode material coating material C: Sacrificial anode material coating with a specific resistance of 1 kΩ · cm at 28 days of age, using mortar using ordinary cement with sand / cement ratio = 1/1 and water / cement ratio = 70% Material D: Sacrificial anode covering material E: sand / cement ratio = 1/1, water / cement ratio = 65% mortar made of ordinary cement and having a specific resistance of 10 kΩ · cm at 28 days of age Sacrificial anode material covering material F: sand / cement ratio = 1 / in a mortar using a normal cement with a cement ratio = 1/1 and water / cement ratio = 50% and having a specific resistance of 28 days of age of 100 kΩ · cm. 1. Sacrificial anode with water / cement ratio = 40% mortar using ordinary cement with a specific resistance of 300 kΩ · cm at 28 days of age Dressing G: Sand / cement ratio = 1/1, in mortar with water / cement ratio = 30% ordinary cement, as the specific resistance of the age of 28 days is 500 k [Omega] · cm

Experimental Example 5
An organic-inorganic composite coating curing agent is applied to the sacrificial anode material covering material 8 of the externally installed specimen using the cement concrete blend of 21 N / mm ² in compressive strength of Experimental Example 1, or the sacrificial anode material covering material The experiment was carried out in the same manner as the experiment using the externally installed specimen of Experimental Example 1 except that 8 was covered with the permanent mold shown below. The results are shown in Table 6.

<Materials used>
Organic-inorganic composite film curing agent: acrylic resin-fluorine mica composite film curing agent permanent mold A: 1 mm thick iron plate permanent mold B: 1 mm thick acrylic resin permanent mold C: 1 mm thick chloride Vinyl resin

Experimental Example 6
In the externally installed specimen using a concrete composition with a compressive strength of 21 N / mm ^{2 in} Experimental Example 1, a CA compound having a different CaO / Al ₂ O ₃ molar ratio was added to the sacrificial anode coating material A for 100 parts of cement. The experiment was conducted in the same manner as in the experiment using the externally installed specimen of Experimental Example 1 except that 5 parts were mixed. The results are shown in Table 7.

<Materials used>
CA compound A: CaO / Al ₂ O ₃ molar ratio 0.1, Blaine value 3,000 cm ² / g
CA compound B: CaO / Al ₂ O ₃ molar ratio 0.15, brain value 3,000 cm ² / g
CA compound C: CaO / Al ₂ O ₃ molar ratio 0.4, brain value 3,000 cm ² / g
CA compound D: CaO / Al ₂ O ₃ molar ratio 0.6, Blaine value 3,000 cm ² / g
CA compound E: CaO / Al ₂ O ₃ molar ratio 0.7, brain value 3,000 cm ² / g
CA compound F: CaO / Al ₂ O ₃ molar ratio 0.8, brain value 3,000 cm ² / g

Experimental Example 7
In an externally installed specimen using a concrete composition with a compressive strength of 21 N / mm ^{2 in} Experimental Example 1, 5 parts of a sacrificial anode material coating material A was mixed with 5 parts of a CA compound having a different Blaine value with respect to 100 parts of cement. Except that, the experiment was performed in the same manner as the experiment using the externally installed specimen of Experimental Example 1. The results are shown in Table 8.

<Materials used>
CA compound G: CaO / Al ₂ O ₃ molar ratio 0.4, Blaine value 1,500 cm ² / g
CA compound H: CaO / Al ₂ O ₃ molar ratio 0.4, brain value 2,000 cm ² / g
CA compound I: CaO / Al ₂ O ₃ molar ratio 0.4, brain value 6,000 cm ² / g
CA compound J: CaO / Al ₂ O ₃ molar ratio 0.4, Blaine value 7,000 cm ² / g
CA compound K: CaO / Al ₂ O ₃ molar ratio 0.4, Blaine value 8,000 cm ² / g

  By using the cross-sectional repair method of the present invention, macrocell corrosion, which is a cause of re-deterioration in the cross-sectional repair method, is greatly suppressed, and durability is greatly improved. Moreover, since the replacement of the sacrificial anode material 4 is easy and maintenance is easy when long-term durability is required, it is suitable for the civil engineering and construction fields.

DESCRIPTION OF SYMBOLS 1 Reinforcing bar 2 Concrete hardening body 3 Anode material 4 Sacrificial anode material 5 End part of the joining side of anode material 6 Cross-section repair material 7 Joining interface 8 Sacrificial anode material coating material 9 Potential / polarization resistance measurement point 10 Measuring equipment connection point 11 Epoxy resin

Claims (8)

  A sacrificial anode material 4 comprising a zinc or zinc alloy anode material 3 and a backfill material containing an electrolyte solution having a pH sufficient to avoid generation of anode passivation around the anode material 3 A method of repairing a cross section of a reinforced concrete structure, which is installed on the surface of a hardened concrete body 2 and electrically connects the reinforcing bar 1 and the sacrificial anode material 4 inside the hardened concrete body 2, and the anode material inside the sacrificial anode material 4 3 is located on the joint interface 7 between the cross-section repair material 6 and the hardened concrete body 2 or on the surface of the hardened concrete body 2 within 30 cm from the joint interface 7. A method for repairing the cross section of a reinforced concrete structure, characterized in that a sacrificial anode material 4 is installed.   The sacrificial anode so that the position of the joining interface side end portion 5 of the anode material 3 inside the sacrificial anode material 4 is on the joining interface 7 or the surface of the hardened concrete body 2 within 30 cm from the joining interface 7. The cross-sectional repair method according to claim 1, wherein the material 4 is installed, and the sacrificial anode material 4 is further installed at an arbitrary position on the surface of the hardened concrete body 2.   3. The cross-sectional repair method according to claim 1 or 2, wherein the sacrificial anode material 4 is wrapped with a sacrificial anode material covering material 8.   The cross-section repair method according to claim 3, wherein the specific resistance of the sacrificial anode material covering material 8 is 1 to 300 kΩ · cm. 5. The cross-sectional repair method according to claim 3, wherein 50 to 500 g of an organic-inorganic composite emulsion is applied to the surface of the sacrificial anode material covering material 8 per 1 m ² .   6. The cross-sectional repair method according to claim 3, wherein a permanent mold is installed on the surface of the sacrificial anode material covering material 8.   The cross-section repair method according to any one of claims 1 to 6, wherein a conductive wire that electrically connects the reinforcing bar 1 and the sacrificial anode material 4 is replaceable. The sacrificial anode material covering material 8 contains a calcium aluminate compound having a CaO / Al ₂ O ₃ molar ratio of 0.15 to 0.7 and a brain surface area value of 2,000 to 7,000 cm ² / g. The cross-section repair method according to claim 7.

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