JP5631024B2 - Anti-corrosion method for reinforcing bars inside reinforced concrete structures - Google Patents

Description

  The present invention mainly relates to a steel bar anticorrosion method for improving the durability of a concrete structure in a marine environment, that is, seawater resistance and corrosion resistance.

  In recent years, there has been an increasing demand for improving the durability of concrete structures in the civil engineering and construction fields.

  As one of the deterioration factors of concrete structures, there is salt damage in which reinforcing bars corrode by chloride ions.

  In offshore structures, salt infiltrates inside the reinforced concrete due to incoming salt, and the reinforcing bars rust. On roads in cold regions, salt damage occurs due to the application of antifreezing agents such as sodium chloride and calcium chloride. In addition, salt damage occurs due to the internal salt even in concrete containing sea sand or admixture containing chloride ions.

A method of adding nitrite or nitrite-type hydrocalumite has been proposed for the purpose of rust prevention of reinforcing bars (see Patent Documents 1 to 3).
Nitrite shows rust prevention effect, but does not show blocking effect of chloride ions entering from the outside, and nitrite type hydrocalumite shows rust prevention effect, but this is not mixed The cemented hardened body is likely to be porous, but rather to allow permeation of chloride ions from the outside.

  On the other hand, as a method for preventing corrosion of reinforcing bars, a sacrificial anode material type cathodic protection method using a difference in standard electrode potential of metal is known. This sacrificial anode material type cathodic protection method is characterized in that an external electrode is not required, maintenance is easy, and long-term anticorrosion properties are excellent (see Patent Document 4).

  In repairing the cross section of a reinforced concrete structure damaged by salt damage, the concrete containing a large amount of chloride ions is picked up, the sacrificial anode material is electrically connected to the rebar, and then filled and covered with the cross-section repair material.

  However, it has not been known at all what kind of cross-sectional repair material is suitable for enhancing the corrosion protection effect of the sacrificial anode material and enhancing the salt damage resistance.

In addition, when a crack occurs in the cross-sectional repair material, it becomes difficult for the anticorrosion current to flow, and therefore it is necessary to reduce the shrinkage that is the cause of the crack.
As a method for reducing the shrinkage of the cross-sectional repair material, an expansion material, a shrinkage reducing agent, and / or fibers are used in combination, and further, two types of expansion materials having different compositions and particle sizes are used in combination. It has been proposed (see Patent Document 5 and Patent Document 6).

Moreover, by applying an organic-inorganic composite-type coating curing agent to the surface of a hardened body of mortar or concrete, in addition to reducing the dissipation of moisture due to drying of the mortar and concrete and suppressing drying shrinkage, It has been proposed to suppress sexualization and penetration of salt from the outside (see Patent Document 7).
However, what effect does the organic-inorganic composite-type coating curing agent have on the anticorrosive effect of the sacrificial anode material when it is applied to the surface of a mortar or concrete cured body coated with a cross-sectional restoration material? Was not known about.

  The present inventor has found that the sacrificial anode material is provided inside the specific cross-sectional repair material, thereby improving the anticorrosion effect and obtaining excellent salt damage resistance, and has completed the present invention.

JP-A-53-003423 Japanese Patent Laid-Open No. 01-103970 Japanese Patent Laid-Open No. 04-154648 Japanese Patent No. 3099830 JP 2007-238745 A JP 2007-320832 A JP 2007-308354 A

  The present invention provides a method for improving the durability of a reinforced concrete structure in a salt damage environment.

The present invention employs the following means in order to solve the above problems.
(1) In the corrosion prevention method for reinforcing steel inside the reinforced concrete that repairs the cross section of the reinforced concrete structure damaged by salt damage, cement and expansion with electrical resistivity 0.5 to 5 times that of concrete in the reinforced concrete structure (age 28 days) 100 to 500 g of organic-inorganic composite type coating curing agent on the surface of the reinforced concrete covered with the cross-sectional repair material containing the material, shrinkage reducing agent, fiber and polymer, and covering the surface of the reinforced concrete covered with the cross-sectional repair material. / m ² coated becomes, the said established the sacrificial anode material in the interior of the cross restorative material, around the sacrificial anode material, having a sufficient pH to avoid the formation of passivation of the sacrificial anode material, the alkaline Reinforced concrete interior comprising a porous material containing an electrolyte solution containing a silica reaction inhibitor and electrically connecting the sacrificial anode material and the rebar inside the reinforced concrete It is a corrosion protection method of rebar.
(2) The anticorrosion method according to (1), wherein the sacrificial anode material and the reinforcing steel inside the reinforced concrete are electrically connected, and the depolarization amount is 310 mV or more.
(3) The anticorrosion method according to (1) or (2), wherein the alkali silica reaction inhibitor contains a lithium-containing compound.
(4) The anticorrosion according to any one of (1) to (3), wherein the metal of the sacrificial anode material is a metal or alloy containing one or more selected from the group consisting of zinc, aluminum, and magnesium. It is a construction method.
( 5 ) The anticorrosion method according to any one of (1) to (4), wherein the organic-inorganic composite-type coating film curing agent comprises a synthetic resin aqueous dispersion, a water-soluble resin, and a swellable clay mineral. It is.
( 6 ) The anticorrosion method according to ( 5 ), wherein the swellable clay mineral of the organic-inorganic composite type coating film curing agent is a synthetic fluorine mica.

  The present invention gives an excellent rust prevention effect to a reinforced concrete structure, and suppresses corrosion of the reinforcing steel inside the reinforced concrete, thereby improving the salt damage resistance.

Hereinafter, the present invention will be described in detail.
In the present invention, “parts” and “%” are based on mass unless otherwise specified.
Moreover, the cross-sectional repair material as used in the field of this invention refers to cement paste, mortar, and concrete.

  In the present invention, the salt damage resistance of the reinforced concrete is improved by installing the sacrificial anode material inside the specific cross-sectional repair material.

  The cross-sectional repair material of the present invention is prepared by kneading using cement or the like.

  As the cement, various portland cements such as normal, early strength, super early strength, low heat, and moderate heat, various mixed cements in which these portland cements are mixed with blast furnace slag, fly ash, or silica, limestone powder and blast furnace Examples include filler cement mixed with slow-cooled slag fine powder, and environmentally friendly cement made from various industrial wastes as the main raw material, so-called eco-cement. One or more of these can be used. It is.

When a crack occurs in the cross-sectional repair material, it becomes difficult for the anticorrosion current to flow, so it is necessary to reduce the shrinkage that is the cause of the crack. Therefore, in the present invention, expansive, shrinkage reducing agents, you combination及beauty textiles.

  Here, the expansion material is not particularly limited, and any material can be used. Although the thing containing free lime and free magnesia is mentioned as the kind, From the viewpoint of long-term stability, the expansion | swelling material containing free lime is preferable.

Examples of the expanding material containing free lime include a free lime-anhydrous gypsum-based expanding material, a free lime-hydraulic compound-based expanding material, and a free lime-hydraulic compound-anhydrous gypsum-based expanding material.
In this invention, since expansion | swelling performance is favorable, it is preferable to use a free lime-hydraulic compound-anhydrous gypsum-type expansion | swelling material.

  Here, examples of the hydraulic compound include one or more of Auin, calcium ferrite, calcium aluminoferrite, calcium silicate, and calcium aluminate.

In the free lime-hydraulic compound-anhydrous gypsum-based expansive material, the expansive material in which the hydraulic compound is composed of one or more of Auin, calcium ferrite, and calcium aluminoferrite produces slaked lime from the free lime. At the same time, ettringite is also produced from hydraulic compounds and anhydrous gypsum. For this reason, there exist what is called a calcium sulfoaluminate type | system | group expansion | swelling material and what is called an ettringite-lime composite type | system | group expansion | swelling material in connection with ettringite.
As such an expanding material, an expanding material or a static crushing material marketed by each company can be used. A large number of inflatables and static crushed materials are commercially available, and representative examples thereof include those manufactured by Denki Kagaku Kogyo Co., Ltd., trade names “Denka CSA” and “Denka Power CSA”, Sumitomo Osaka Cement Co., Ltd. ", Trade name" Expan "," N-EX "," Breister ", and" Pacific Gypcal "manufactured by Taiheiyo Material.

The particle size of the intumescent material is not particularly limited, but usually it is preferably 2,500 to 10,000 cm ² / g in terms of the specific surface area of brain (hereinafter referred to as “brain value”).
The amount of the expansion material used is preferably 2 to 30 parts with respect to 100 parts of cement.

As the shrinkage reducing agent, the shrinkage reducing component is represented by the general formula RO (AO) nH (where R is an alkyl group having 4 to 6 carbon atoms, A is one or two alkylene groups having 2 to 3 carbon atoms, and n is 1). Or an alkylene oxide adduct of a lower alcohol represented by the general formula X {O (AO) nR} m (where X is a residue of a compound having 2 to 8 hydroxyl groups) AO is an oxyalkylene group having 2 to 18 carbon atoms, R is a hydrogen atom, a hydrocarbon group having 1 to 18 carbon atoms, or an acyl group having 2 to 18 carbon atoms, n is 30 to 1,000, and m is 2 to 8) A polyoxyalkylene derivative in which 60 mol% or more of the oxyalkylene group is an oxyethylene group can be used.
The amount of shrinkage reducing agent used is preferably 1 to 6 parts per 100 parts of cement.

The fibers are not particularly limited, and commercially available products can be used, and specific examples include high-strength vinylon fibers and polyethylene fibers.
The amount of fibers used is preferably 0.01 to 1.0 part by volume in 100 parts by volume of the cross-sectional repair material.

The fine aggregate used in the present invention is not particularly limited. Specific examples thereof include silica sand, lime sand, blast furnace granulated slag fine aggregate, recycled fine aggregate, and heavy fine aggregate. In addition, blast furnace slow-cooled slag fine aggregate, electric furnace oxidation stage slag fine aggregate, and non-ferrous smelted slag fine aggregate that collectively refers to ferronickel slag, ferrochrome slag, copper slag, zinc slag, lead slag, etc. Furthermore, a peridotite fine aggregate, so-called olivine sand, emery ore and the like can be mentioned. In the present invention, one or more of these can be used.
The amount of fine aggregate used is not particularly limited, and is appropriately adjusted according to the application and required workability.

The cross-sectional repair material of the present invention includes cement, expansion material, shrinkage reduction material, fiber, polymer, fine aggregate, water, and the like, blast furnace granulated slag fine powder and blast furnace annealed slag fine powder, silica fume, fly ash, Limestone fine powder, sewage sludge incineration ash and its molten slag, municipal waste incineration ash and its molten slag, various hardeners, high strength admixtures, water reducing agents, AE water reducing agents, high performance water reducing agents, high performance AE water reducing agent, coagulation adjusting agents, antifoaming agents, thickening agents, rust inhibitors, antifreezing agents, clay minerals, such as base bentonite, as well as one or two kind of anion exchanger or the like, such as hydrotalcite The present invention can be used within a range that does not substantially impair the object of the present invention.

  In the present invention, the respective materials may be mixed at the time of construction, or a part or all of them may be mixed in advance.

  Any existing apparatus can be used as the mixing apparatus, and for example, a tilting cylinder mixer, an omni mixer, a Henschel mixer, a V-type mixer, and a Nauta mixer can be used.

The electric resistivity of concrete in a concrete structure varies depending on the concrete composition and environment, but is usually about 100 Ω · m.
The electrical resistivity of the cross-sectional repair material in the present invention is 0.5 to 5 times the electrical resistivity of the concrete in the reinforced concrete structure. If the electrical resistivity is less than 0.1 times, the amount of depolarization becomes small, and the rebar inside the concrete structure may be easily corroded. When the electrical resistivity is small, the anticorrosion current easily flows, but at the same time, the corrosion current easily flows. The presence or absence of corrosion of the reinforcing bars is determined by these balances, and since the influence of the corrosion current is large, it is considered that the corrosion is likely to proceed. If the electrical resistivity exceeds 10 times, the corrosion resistance current is difficult to flow because the electrical resistance is high, the corrosion protection range is narrowed, and the corrosion protection effect of the sacrificial anode material may be reduced.
The electrical resistivity of the cross-sectional repair material can be adjusted by adjusting the water binder ratio, mixing various admixtures and carbon fibers, using polymer cement mortar with different amounts of polymer.

  Here, the binder is made of cement or cement, an expanding material, and various admixtures.

  Examples of the polymer include an aqueous polymer dispersion and are not particularly limited. Examples of aqueous polymer dispersions include natural rubber latex, synthetic rubber latex such as acrylic rubber, styrene / butadiene rubber (SBR), and chloroprene rubber (CR), ethylene / vinyl acetate copolymer (EVA), and polyacrylic acid. Examples thereof include resin emulsions such as esters (PAE) and polyacrylic acid-vinyl acetate-veova polymers. Examples of the polymer form include a re-emulsification type powder type and a liquid type.

  In the present invention, applying an organic-inorganic composite type coating curing agent to the surface of a cured body (hereinafter referred to as the present cured body) cured using the cross-sectional repair material of the present invention further reduces the amount of shrinkage. In addition, not only can cracking be suppressed, but the electrical resistance of the cured product can be kept constant over a long period of time.

  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.
Among them, 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 preferable.
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 with respect to 100 parts of the 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 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” and “Krakoff” manufactured by Denki Kagaku Kogyo Co., Ltd. and “CA2” series manufactured by Toagosei Co., Ltd. can be used.

  By applying the organic-inorganic composite-type film curing agent of the present invention to the cured body, not only can the length change rate be further reduced to suppress cracking, but also the electrical resistance of the cured body over the long term. It can be kept constant and the anticorrosion effect can be enhanced.

Although the usage-amount of an organic-inorganic composite type coating film curing agent is not specifically limited, 100-500g is preferable per 1 m < ² > of reinforced concrete, 150-300g is more preferable. If it is less than 100 g, there is a possibility that the effect of keeping the electric resistance small in the long term may not be sufficient, and even if it is applied over 500 g, the effect reaches its peak.

  In the present invention, a reinforcing bar inside the reinforced concrete is used as a cathode, a sacrificial anode material is installed inside the reinforced concrete, and the two are electrically connected, thereby supplying a corrosion-proof current to the reinforcing bar to prevent the reinforcing bar.

  As a metal which comprises a sacrificial anode material, the metal or alloy containing 1 type, or 2 or more types chosen from the group which consists of zinc, aluminum, and magnesium is mentioned.

  In order to avoid passivation of the sacrificial anode material, it is necessary to attach a porous material around the sacrificial anode material and maintain the periphery of the metal of the sacrificial anode material at a predetermined pH. For example, in the case of a zinc-aluminum alloy, the pH value needs to be 13.3 or more, and the pH value for suppressing passivation is different depending on the metal used.

The porous material provided around the sacrificial anode material is preferably an inorganic material having a water retention function, and more preferably a cement-based mortar material similar to concrete. Since the porous material has a water retention function, the metal of the sacrificial anode material is eluted into the liquid in the porous material, thereby fulfilling the function of the sacrificial anode material.
In order to obtain a porous material, a lightweight fine aggregate, foaming agent, expansion material, etc. are used as the admixture, or the amount of air in the mortar is adjusted appropriately to produce a mortar that has not yet solidified. This is coated with the metal of the sacrificial anode material to form a porous coating in which pores are dispersed in a cured state. In mixing the mortar, an alkali metal compound can be added to obtain a mortar having a further increased alkalinity.

The electrolyte solution used in the present invention, with sufficient pH to avoid the formation of non-dynamic state of the sacrificial anode material, if a solution containing alkali metal ions, but are not limited to, Potassium hydroxide, sodium hydroxide, lithium hydroxide solution and the like can usually be used.

Since the pH of the electrolyte solution contained in the porous material attached around the sacrificial anode material is high, there is a concern about the alkali silica reaction in the concrete portion adjacent to the porous material. Therefore, in the present invention, Ru in the presence of an alkali silica reaction inhibitor to the electrolyte solution.

  The alkali silica reaction inhibitor is preferably a lithium-containing compound in order to avoid a decrease in pH of the electrolyte solution, and it is preferable to add lithium hydroxide, lithium carbonate, or lithium-type zeolite.

  The method of electrically connecting the reinforcing bar and the sacrificial anode material is not particularly limited as long as the reinforcing bar and the metal constituting the sacrificial anode material are electrically connected to each other. A method of embedding a metal wire in a metal and winding it around a reinforcing bar is practically simple.

  When the anticorrosion current flows from the sacrificial anode material to the reinforcing bar, the anode of the sacrificial anode material becomes an oxide and the volume increases. In some cases, the oxide is deposited on the surface of the anode, the potential is increased, and the anticorrosion effect is lowered. Therefore, by attaching a porous material around the sacrificial anode material, it is possible to prevent volume expansion and deterioration of the anticorrosion effect.

  In the present invention, after partially filling the concrete structure, a sacrificial anode material is installed, and the metal and the reinforcing bar are electrically connected. The metal surface has a pH sufficient to avoid the formation of a non-conductive coating. After covering with a porous material containing an electrolyte solution, a concrete structure is constructed by placing concrete and embedding the sacrificial anode material. The rebar is protected against corrosion.

In the present invention, the anticorrosion effect of the reinforcing bars can be confirmed by measuring the potential.
When a metal having a standard electrode potential lower than that of the reinforcing bar is electrically connected to the reinforcing bar inside the reinforced concrete, the potential of the reinforcing bar itself is lowered. Therefore, the effectiveness can be judged from the numerical value by measuring the potential.
The electric potential is measured using the lead verification electrode with the surface where the sacrificial anode material of the reinforcing bar in the concrete is installed as the measurement point. At this time, the sacrificial anode material and the reinforcing bar can be disconnected, and the instant-off potential immediately after disconnecting and the potential after 24 hours (off-potential after 24 hours) are measured and recovered from these differences. Calculate the extreme amount. The greater the amount of depolarization, the greater the effect of preventing corrosion of the reinforcing bars.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and the content of this invention is demonstrated in detail, this invention is not limited to these.

Experimental example 1
An experiment was conducted assuming the restoration of a cross section of a concrete structure damaged by salt.
As the concrete subjected to salt damage, a concrete having a unit cement amount of 330 kg / m ³ , a water cement ratio of 60%, s / a of 52%, and an addition amount of NaCl of 12 kg / m ³ was prepared. The concrete had an electrical resistivity of 100 Ω · m.
100 parts of cement contains 5 parts of expanded material, 5 parts of expanded material, 3 parts of shrinkage reducing agent, fine aggregate, water reducing agent, polymer, and fiber a and fiber b. As shown in Table 1, cross-sectional restoration materials having different electrical resistivity were prepared by changing the addition ratio of b.
The prepared cross-sectional repair material was packed in a mold to prepare a 4 × 4 × 16 cm specimen, and the length change rate was measured at a material age of 28 days. In addition, a cross-sectional repair material prepared to be 30 cm long, 30 cm wide and 3 cm thick was placed on an existing concrete plate, and the occurrence of cracks was observed at the age of 28 days.
Using a 15 × 15 × 53 cm formwork, concrete was cast in half of the axial direction, and a cross-sectional repair material was cast in the remaining half to prepare a test specimen. At this time, a φ13 mm post-rolled steel bar was installed in the center of the specimen in the axial direction, and a sacrificial anode material A was installed on the cross-sectional repair material side. Lead wires were connected to the polished steel bar and the sacrificial anode material, respectively, so that the electrical connection could be turned on and off outside the specimen. The specimen was heated to 40 ° C. to promote corrosion of the reinforcing bars.
On the surface where the sacrificial anode material inside the cross-section repair material is installed, the point corresponding to the center of the reinforcing bar is taken as the measurement point, and using the lead verification electrode, the instant-off potential and the off-potential after 24 hours are measured. The amount of depolarization was calculated. The polished steel bar and the sacrificial anode material were electrically connected except when the amount of depolarization was measured. The presence or absence of rusting on the polished steel bar was observed to confirm the rust prevention effect. The results are also shown in Table 1.

<Materials used>
Cement: Ordinary Portland cement, density 3.15g / cm ³ , brain value 3,100cm ² / g
Expandable material a: Ettlingite-lime composite expanded material, brain value 3,000 cm ² / g
Expansion material b: calcium sulfoaluminate-based expansion material, brain value 6,000 cm ² / g
Shrinkage reducing agent: powder shrinkage reducing agent, commercially available polymer: polyacrylic acid-vinyl acetate-veova powder polymer, commercially available fiber a: vinylon fiber, commercially available fiber b: carbon fiber, commercially available water reducing agent: polycarboxylic acid type Water reducing agent, commercially available fine aggregate: river sand, density 2.62 g / cm ³ , no alkali silica reactivity coarse aggregate: river gravel, density 2.64 g / cm ³ , no alkali silica reactivity sodium chloride (NaCl): salt, Commercial water: Tap water sacrificial anode material A: Zinc block covered with porous mortar containing LiOH as alkali silica reaction inhibitor

<Measurement method>
Electrical resistivity: Demolded the day after the specimen was prepared, cured at 20 ° C and 60% RH, and measured by a four-electrode method at a material age of 28 days.
Length change rate: Conforms to JIS A 1171. Evaluation of shrinkage Cracking: Crack resistance is not acceptable when cracking occurs, and when cracking does not occur.
Depolarization amount: At 6 months of age, using a lead verification electrode, the instant-off potential immediately after cutting the electrical connection between the reinforcing steel inside the concrete and the sacrificial anode material, and 24 hours after turning off, 24 hours after turning off The potential was measured, and the amount of repolarization was calculated by the following equation.
Depolarization amount (mV) = [Eio (mV)] − [Eof (mV)]
Eio: Instant-off potential Eof: Off-potential rust prevention effect after 24 hours: The presence or absence of rust on the reinforcing bars was confirmed at 6 months of age. When the rust did not occur in the reinforcing bars, it was good. When the rust occurred within 1/10 of the area, it was acceptable. When the rust exceeded the 1/10 area, it was not acceptable.

  From Table 1, it can be seen that, according to the present invention, when the electrical resistivity of the cross-sectional repair material is 0.1 to 10 times that of concrete, an excellent rust prevention effect is imparted and salt damage resistance is improved. Moreover, since the shrinkage can be reduced and cracks can be reduced by the combined use of the expansion material, the shrinkage reducing agent, and the fiber, the anticorrosion effect can be maintained.

Experimental example 2
In Experiment No. 1-5, the sacrificial anode material shown in Table 2 was installed inside the cross-section restoration material, and the alkali silica reactive aggregate was blended to examine whether or not there was an inhibitory effect on the alkali silica reaction (ASR). Except that, the same procedure as in Experimental Example 1 was performed. For comparison, the case where no sacrificial anode material was installed or the case where an alkali silica reaction inhibitor was not included in the porous mortar around the metal was examined. The results are also shown in Table 2.

<Materials used>
Sacrificial anode material B: Zinc-aluminum alloy sacrificial anode material C covered with porous mortar containing LiOH as an alkaline silica reaction inhibitor and having a zinc / aluminum ratio of 1/1: Alkaline silica reaction inhibitor Aluminum lump sacrificial anode material D covered with porous mortar containing LiOH: Magnesium lump sacrificial anode material E covered with porous mortar containing LiOH as an alkaline silica reaction inhibitor E: Alkali silica reaction inhibitor Zinc-magnesium alloy sacrificial anode material with a zinc / magnesium ratio of 1/1 covered with porous mortar containing LiOH as F: covered with porous mortar containing LiOH as alkaline silica reaction inhibitor Further, an aluminum magnesium alloy sacrificial anode material G having an aluminum / magnesium ratio of 1/1: Zinc / aluminum / magnesium alloy sacrificial anode material with a zinc / aluminum / magnesium ratio of 1/1/1 covered with porous mortar containing LiOH as an inhibitor: porous without alkali silica reaction inhibitor Zinc blocks covered with mortar

<Measurement method>
ASR suppression effect: A 10 × 10 × 40 cm cross-section repair material test specimen was prepared in which a φ13 mm post-rolled steel bar was installed at the center in the axial direction and a sacrificial anode material was installed. Curing at 40 ° C and measuring the rate of change in length. If the rate of change in length at the age of 6 months is less than 500 x 10 ^-6, "good", if it is 500 to 1,000 x 10 ^-6 , "good""If it exceeds 1,000 x 10 ^-6 ,"

  From Table 2, it can be seen that according to the present invention, an excellent rust prevention effect is imparted to the reinforced concrete and the salt damage resistance is improved. In addition, from Experiment No. 2-8, when the alkali silicate reaction inhibitor is not included in the porous mortar around the metal, the metal is passivated, so the amount of depolarization is small.

Experimental example 3
In Experiment No. 1-5, the organic-inorganic composite type film curing agent was applied to the surface of the cross-section repair material in the amount shown in Table 3, and after 1 month, 3 months, 6 months, and 1 year This was carried out in the same manner as in Experimental Example 1 except that the electrical resistivity of the cured mortar was measured.
In addition, it carried out similarly about the case where the conventional coating-film curing agent is apply | coated as a comparison with the case where an organic-inorganic composite type coating-film curing agent is not used. The results are also shown in Table 3.

<Materials used>
Organic-inorganic composite coating curing agent: Acrylic resin-fluorine mica composite coating curing agent Conventional coating curing agent: EVA coating curing agent, commercial product

  From Table 3, by applying an organic-inorganic composite coating film curing agent to the surface of the cross-sectional repair material of the present invention, it is possible to suppress shrinkage and maintain the electrical resistance of the cross-sectional repair material constant over the long term, High anticorrosion effect is obtained.

  The present invention provides an excellent rust preventive effect to cement concrete and improves salt damage resistance, so that it is inside a concrete structure when used for cross-section repair of a concrete structure that has undergone steel corrosion due to salt damage or the like. The anticorrosion effect of steel can be enhanced.

Claims (6)

In the corrosion prevention method for reinforcing steel inside the reinforced concrete to repair the cross section of the reinforced concrete structure damaged by salt damage, cement, expandable material, shrinkage with electric resistivity 0.5 to 5 times that of concrete in the reinforced concrete structure (age 28 days) The surface of the reinforced concrete is covered with a cross-sectional restoration material containing a reducing agent, fiber, and polymer, and an organic-inorganic composite type coating curing agent is applied to the surface of the reinforced concrete coated with the cross-sectional restoration material in an amount of 100 to 500 g / m ^2. A sacrificial anode material is installed inside the cross-sectional repair material , and the alkaline silica reaction is suppressed around the sacrificial anode material and has a pH sufficient to avoid the formation of a passive state of the sacrificial anode material. Reinforced concrete characterized by comprising a porous material containing an electrolyte solution containing an agent and electrically connecting the sacrificial anode material and the reinforcing steel in the reinforced concrete. Corrosion protection method of over Internal rebar. The corrosion prevention method for reinforcing bars in reinforced concrete according to claim 1, wherein the sacrificial anode material and the reinforcing bars in the reinforced concrete are electrically connected, and the repolarization amount is 310 mV or more.   The anticorrosion method for reinforcing steel in a reinforced concrete according to claim 1 or 2, wherein the alkali silica reaction inhibitor contains a lithium-containing compound.   The metal of the said sacrificial anode material is a metal or alloy containing 1 type, or 2 or more types chosen from the group which consists of zinc, aluminum, and magnesium, The any one of Claims 1-3 characterized by the above-mentioned. The anticorrosion method for reinforcing bars inside reinforced concrete as described in 1. The organic-inorganic composite-type film curing agent contains a synthetic resin aqueous dispersion, a water-soluble resin, and a swellable clay mineral, according to any one of claims 1 to 4. Corrosion prevention method for reinforcing steel inside reinforced concrete. The swellable clay mineral of the organic-inorganic composite-type coating film curing agent is a synthetic fluorine mica, The anticorrosion method for reinforcing bars in reinforced concrete according to claim 5 .