JP3766043B2 - Anticorrosion reinforced concrete assembly and its anticorrosion method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an anticorrosion reinforced concrete assembly and an anticorrosion method thereof.
[0002]
[Prior art]
In a concrete structure such as a reinforced concrete structure or a prestressed concrete structure, corrosion of the reinforcing bar or steel material may occur due to permeation of oxygen, water, chloride ions, or the like. When the steel material or the like is corroded in this way, cracks are generated in the concrete due to the corrosion products, further accelerating the corrosion, and finally the strength of the concrete structure is lowered.
[0003]
As an extremely effective method for preventing corrosion of steel materials and the like in a concrete structure, there is an anticorrosion method. In other words, the anode reaction (oxidation reaction) and the cathode reaction (reduction reaction) occur simultaneously on the surface of the steel material or the like in the concrete structure in a state where the potential is not changed, and a corrosion cell is formed as a result. Corrosion occurs due to the occurrence of corrosion, etc., but by changing the potential of the steel material, only the cathode reaction can occur on the surface of the steel material, thereby preventing the generation of iron hydrated oxides, etc. can do.
[0004]
In order to carry out the cathodic protection method, an anode is generally provided on the concrete surface, while steel or the like is used as the cathode. As a result, the current is supplied to the steel material through the concrete to change the potential of the steel material in the base direction, thereby realizing corrosion prevention.
[0005]
The material of the anode provided on the concrete surface is required to have performance such as high electrical conductivity, excellent stability, durability and economy, and simple construction. As the anode that is currently in practical use, titanium wire, zinc, carbon fiber wire, etc. with a platinum metal oxide coated on the surface are used.
[0006]
In particular, when a carbon fiber sheet is used as the anode, by covering the concrete surface broadly, the potential distribution on the concrete surface can be made more uniform, and the generation of chlorine gas on the anode surface can be suppressed, In addition, the strength of the concrete structure can be reinforced by the carbon fiber sheet.
[0007]
In these carbon fiber sheets, carbon fibers such as unidirectional materials are usually arranged in parallel to one or more directions in the sheet. And the proof stress of a concrete structure can be reinforced with the tensile strength of the carbon fiber along the direction of this carbon fiber.
Thus, when applying a carbon fiber sheet as an anode and a proof stress reinforcement for cathodic protection, a carbon fiber sheet is affixed on the concrete structure surface with a conductive adhesive. This conductive adhesive is required to have a high electrical conductivity in order to allow a sufficient current to flow from the carbon fiber sheet to the steel material, and at the same time, a large adhesion strength is required to reinforce the concrete structure. However, it is difficult to freely adjust the conductivity and adhesion strength of the conductive adhesive.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide an anticorrosion-reinforced concrete assembly in which a carbon fiber sheet is fixed to a concrete structure so as to have both conductivity and adhesion strength, and to obtain both an anticorrosion effect and a reinforcement effect, and the anticorrosion It is to provide a method.
[0009]
[Means for Solving the Problems]
In order to solve the conventional problems, in the present invention, a concrete structure including concrete and a steel material provided in the concrete, a carbon fiber sheet provided on the surface of the concrete structure, the steel material, and the steel and a current supply means connected to the carbon fiber sheet, between the concrete structure surface and the carbon fiber sheet, the adhesive layer exhibiting 20 kgf / cm ² or more bonding strength between the both said person, said than the adhesive conductivity rather high, corrosion reinforced concrete, characterized in that a volume resistivity of 10 [Omega · cm or less conductive materials layer was placed in divided so as not to overlap to attach the two An assembly is provided.
In the present invention, since the adhesive layer and the conductive material layer are arranged so as not to overlap between the concrete structure surface and the carbon fiber sheet, the carbon fiber sheet is firmly attached to the concrete structure surface by the adhesive layer. The tensile strength of the carbon fiber itself reinforces the strength of the concrete structure, and the conductive material layer enables the use of a conductive material with excellent conductive performance and durability. In addition, when performing anticorrosion, it is possible to provide a stable potential distribution over the entire surface of the concrete structure, and it is possible to achieve anticorrosion without increasing the energizing voltage. In other words, in many cases, conductive materials with excellent conductive performance and durability tend to have low adhesion strength. Therefore, if the adhesive layer and conductive material layer are placed separately, the strength reinforcement effect and anticorrosion can be achieved. Both effects can be achieved.
[0010]
According to the present invention, there is also provided a corrosion prevention method for an anticorrosion reinforced concrete assembly, wherein current is applied so that the steel material of the anticorrosion reinforced concrete assembly is a cathode and the carbon fiber sheet is an anode.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The carbon fiber sheet is a conductive sheet containing carbon fibers. Specifically, carbon fibers having a diameter of 7 to 10 μm extending in the length direction of the sheet are densely, for example, 1,000 per 1 m in the width direction. A sheet having a thickness of 0.05 to 0.2 mm can be mentioned which is woven in a line of ten thousand or more. As such a carbon fiber sheet, for example, “TU cloth” (trade name, manufactured by Mitsubishi Corporation) can be used.
[0012]
The volume resistivity of the carbon fiber sheet is preferably 5 × 10 ⁻⁴ to 1 × 10 ⁻³ Ω · cm because the charging voltage of the anode can be further reduced.
Tensile strength of the carbon fiber sheet is about 30,000kgf / cm ² or more, particularly about 35,000~72,000kgf / cm ² or more and a tensile modulus of elasticity of about 2.35 × 10 ⁶ ~8.00 × 10 ⁶ kgf / cm ² is preferable because a high-strength concrete anticorrosion reinforcing device can be obtained.
[0013]
The carbon fiber sheet is a unidirectional sheet (one in which carbon fibers are densely arranged in only one direction on the surface of the sheet), and a bi-directional sheet (one direction on the surface of the sheet and a direction perpendicular thereto). Any of those in which carbon fibers are densely arranged) and those in which carbon fibers are arranged in more directions may be used. In particular, a unidirectional sheet that is excellent in linearity and can more efficiently utilize the tensile strength of carbon fiber is preferable.
Moreover, the said carbon fiber sheet can contain other fibers other than a carbon fiber. Specifically, for example, fibers such as glass fibers for holding unidirectional carbon fibers can be included.
[0014]
The carbon fiber sheet may have a shape that conforms to the surface of a concrete structure having a rectangular shape or other shape, and can usually have a rectangular shape in which carbon fibers are densely arranged in at least the length direction thereof. .
[0015]
In the assembly of the present invention, it is preferable that the carbon fiber sheet is provided on the surface of the concrete structure so that the tensile strength of the carbon fibers is in a direction to reinforce the concrete structure. Specifically, for example, a carbon fiber sheet can be provided on the bottom surface of an elongated rectangular parallelepiped beam so that the carbon fibers extend in the length direction. Moreover, in order to achieve the anticorrosion of the entire surface of the concrete structure, the anticorrosion reinforcing device and / or another electrode for anticorrosion can be provided on a surface other than the surface requiring reinforcement. Furthermore, in order to achieve sufficient reinforcement, two or more layers of carbon fiber sheets can be provided on the concrete structure surface as necessary.
[0016]
When the carbon fiber sheet is provided on the surface of the concrete structure, the carbon fiber sheet is attached to the surface of the concrete structure with the adhesive layer and the conductive material layer, and then an adhesive such as an epoxy resin is further added to the carbon. It is preferable to impregnate the fiber sheet, thereby improving the adhesive strength and durability of the carbon fiber sheet.
[0017]
The carbon fiber sheet, for example, it is possible to use a sheet thinly and uniformly coated with a metal having a high oxidation power, such as nickel. The embodiment of the coating according to the high oxidation metal, for example, or by thinly and uniformly coat the one single carbon fiber constituting the carbon fiber sheet by carbon fiber, or surface of the sheet, the back side, the end side thinly and uniformly or to coat all, it is any aspect can be selected. Thus, if a carbon fiber sheet is coat | covered with a high oxidation-resistant metal, the polarization resistance of the carbon fiber sheet as an anode material can be made small, and consumption of carbon can be reduced.
[0018]
It is preferable that the adhesive layer and the conductive material layer are arranged in a striped pattern extending in the fiber direction of the carbon fiber sheet that is the unidirectional sheet so as not to overlap . In this arrangement, Ru can be uniformly partition the respective electrode portions and the reinforcing portion of the carbon fiber sheet. In this case, there is an effect that the electrode function and the reinforcing function can be used effectively and uniformly because the electrical conductivity and tensile strength in the fiber direction are extremely high compared to the direction perpendicular to the fiber.
[0019]
The conductive material layer is made of a material that has moisture retention performance and conductivity that is better than that of an adhesive, and has an adhesive force that prevents the carbon fiber sheet from peeling off from the surface of the concrete structure. The conductive material layer is in contact resistance low suppression of the carbon fiber sheet and the concrete structure surface, also set to the extent capable of holding the ability of the carbon fiber sheet as a galvanic anode, hard phased volume resistance when It is a layer having a rate of 10 Ω · cm or less . Moreover, it is preferable that a water | moisture retention performance is a grade which can suppress the electrical potential increase of the carbon fiber sheet as a galvanic anode.
[0020]
The conductive material layer can be made of a material containing, for example, bentonite, quicklime, MgSO ₄ , or MgCl ₂ . Although it is not possible to expect adhesion strength with this material, good results are obtained in terms of moisture retention performance.
The conductive material layer can be made of a material containing, for example, gypsum (MgSO ₄ · H ₂ O), NaCl, and graphite. This material cannot be expected to have much adhesion strength as described above, but has an excellent effect in terms of reducing the contact resistance between the carbon fiber sheet and the concrete structure surface. In addition, you may use the said graphite provided with metal films, such as nickel, in the particle | grains.
[0021]
The adhesive layer may be any layer as long as the carbon fiber sheet adheres firmly to the surface of the concrete structure. 20 kgf / cm ² or more bonding strength is a layer that is obtained in the.
[0022]
The assembly of the present invention includes a current-carrying device for supplying a corrosion-proof current. The energization device is not particularly limited as long as it can supply the anticorrosion current, and various DC stabilized power supply devices such as commercially available ones can be used. It is preferable that a steel material is connected to the cathode of the current-carrying device and a carbon fiber sheet is connected to the anode of the current-carrying device because the anticorrosion can be effectively performed. The connection between the current-carrying device and the carbon fiber sheet is not particularly limited as long as electrical connection is achieved, and may be detachable, fixed, or integrally formed.
[0023]
The anticorrosion reinforced concrete assembly of the present invention can include a reference electrode for adjusting the amount of anticorrosion current in the electrocorrosion prevention, confirming the anticorrosion effect by the reinforcing bar potential, and the like, if necessary. As the reference electrode, a silver chloride electrode or a lead electrode can be used. The reference electrode is preferably provided in the vicinity of the steel material in the concrete structure.
[0024]
The concrete constituting the concrete structure includes hardened mortar, cement paste, etc. in addition to ordinary concrete including cement, water, fine aggregate, coarse aggregate and the like. The concrete structure is a structure including the concrete and a steel material. The steel material refers to a metal widely provided in concrete, and a metal provided in concrete for the purpose of enhancing the durability of concrete, such as a steel material provided in reinforced concrete and a steel material provided in prestressed concrete. Including.
[0025]
The anticorrosion reinforced concrete assembly of the present invention can be assembled for newly constructing a concrete structure, but as a repair of the existing concrete structure, the carbon fiber sheet is provided on the surface of the existing concrete structure, It can also be assembled by connecting a current-carrying device so that the steel material in the existing concrete is the cathode and the carbon fiber sheet is the anode.
[0026]
When assembling the anticorrosion reinforced concrete assembly of the present invention as a repair of an existing concrete structure, prior to the provision of the anticorrosion reinforcement device, the steel material in the concrete structure is provided with a drain terminal, etc. It is preferable to provide the reference electrode in Moreover, it is preferable to confirm whether all the steel materials in the concrete structure are electrically connected and to conduct the steel materials by welding or the like as necessary. Then, it is preferable to perform a treatment such as removing dirt, latency, etc. adhering to the surface of the concrete structure by sandblasting, ultra-high pressure water jet or the like, and further removing concrete powder with compressed air.
[0027]
The carbon fiber sheet is affixed by applying a masking tape in a vertical stripe pattern on the surface of the dried concrete structure, and uniformly applying an adhesive with a roller brush or a rubber spatula on the concrete surface on which the masking tape is not applied. After stripping the tape and applying a conductive material to the concrete surface to which no adhesive has been applied, the carbon fiber sheet is immediately attached, and the sheet surface is further rubbed with a rubber blade or the like in the fiber direction, and the adhesion for impregnation is further performed. It can be performed by impregnating the agent.
[0028]
In the anticorrosion method of the present invention, corrosion can be prevented by energizing the steel material in the anticorrosion reinforced concrete assembly as a cathode and the carbon fiber sheet as an anode.
[0029]
Since the preferable energization amount at the time of energization varies depending on the structure of the anticorrosion reinforced concrete assembly, etc., it is preferably determined by an energization test. Specifically, it can be determined by the following procedure.
1) The natural potential of the steel material is measured.
2) Obtain the relationship between the amount of energized current and the potential of the steel material by a polarization test.
3) An energization current amount for obtaining a required polarization amount from a natural potential is obtained.
4) Energize for 24 hours or longer with the energization current obtained in 3).
5) It is confirmed whether a predetermined depolarization amount (100 mV or more) can be obtained by a depolarization test.
[0030]
【Example】
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.
[0031]
FIG. 3 is a schematic view showing the anticorrosion reinforced concrete assembly 1 of the present invention.
The anticorrosion reinforced concrete assembly 1 is an assembly in which a carbon fiber sheet 5 is provided on an existing reinforced concrete structure 3 and a power supply device 8 is connected to the reinforcing steel 2 and the carbon fiber sheet 5. Between the surface and the carbon fiber sheet 5, the adhesive layer 4a and the conductive material layer 4b are arranged separately so as not to overlap.
[0032]
If it demonstrates in detail, the deterioration part of the existing reinforced concrete structure 3 will be pinched, the surface metal of concrete will be removed, and the concrete surface will be ground-treated with cement paste. A lead wire is connected to the reinforcing bar 2 in the concrete by spot welding, and a discharge terminal 9 and a measurement terminal 12 are provided. And the silver chloride collation electrode 10 was fixed to the reinforcing bar 2 with a plastic band. Further, whether or not all the reinforcing bars 2 existing in the reinforced concrete structure are electrically connected is measured, and if any reinforcing bars are not connected, they are connected by welding and all the reinforcing bars are connected.
[0033]
Next, dirt, latency, etc. adhering to the surface of the concrete structure 3 are removed by sandblasting, ultra-high pressure water jet or the like, and concrete powder is removed by compressed air. After the concrete surface is dried, the adhesive layer 4a and the conductive material layer 4b are applied to the concrete surface in a vertical stripe pattern as shown in the schematic diagram of FIG. That is, a masking tape is applied in a vertical stripe pattern at a plurality of locations on the concrete surface, and an epoxy resin adhesive is uniformly applied to the concrete surface without the masking tape by a roller brush or a rubber spatula. 4a is formed, and then the masking tape is peeled off, and the conductive material layer 4b is formed by applying the conductive material to the vertical stripes where the epoxy resin adhesive 4a is not applied. The sheet surface is rubbed with a rubber spatula in the fiber direction, and the epoxy resin adhesive 6 is impregnated into the fiber from above. In addition, as shown in FIG.2 and FIG.3, it is also possible to affix the carbon fiber sheet 7 on the epoxy resin adhesive 6. FIG.
[0034]
And after connecting the end part of a carbon fiber sheet with lead wire 9b by screwing, it is checked using a direct-current voltmeter that the installed carbon fiber sheet anode is electrically connected.
[0035]
Furthermore, a power supply box that houses the DC power supply device 8 is fixed to a concrete base with anchor bolts. These are connected to the DC power supply device 8 so that the discharge terminal 9a is on the cathode side and the lead wire 9b is on the anode side. All the wires and connection points for connection are treated with an insulating material and a waterproof material.
As described above, the anticorrosion reinforced concrete assembly 1 of the present invention is formed.
[0036]
【The invention's effect】
In the anti-corrosion reinforced concrete assembly of the present invention, the carbon fiber sheet is arranged on the concrete surface by the adhesive layer so that the adhesive layer and the conductive material layer do not overlap each other. While it is firmly attached to the surface and united to reinforce the strength of the concrete structure, the conductive material layer makes it possible to use a conductive material with excellent conductivity and durability, making it stable in the concrete structure. Thus, the anticorrosion can be achieved at a lower voltage compared to the conventional case. Further, since the area ratio between the adhesive layer and the conductive material layer can be easily adjusted, it is possible to freely adjust the anticorrosion effect and the strength reinforcement effect.
[Brief description of the drawings]
FIG. 1 is a schematic view for explaining the configuration of a corrosion-proof reinforced concrete assembly of the present invention.
FIG. 2 is a schematic view for explaining the configuration of the anticorrosion reinforced concrete assembly of the present invention.
FIG. 3 is a schematic view showing an example of the anticorrosion reinforced concrete assembly of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Corrosion-proof reinforced concrete 2 Reinforcement 3 Reinforced concrete structure 4a Adhesive layer 4b Conductive material layer 5 Carbon fiber sheet 6 Epoxy resin adhesive 7 Carbon fiber sheet 8 Power supply device 9 Exhaust terminal 9b Lead wire 10 Reference electrode 11 Voltmeter 12 Measuring terminal

Claims (4)

A concrete structure including concrete and a steel material provided in the concrete; a carbon fiber sheet provided on a surface of the concrete structure; and a current-carrying means connected to the steel material and the carbon fiber sheet.
Between the concrete structure surface and the carbon fiber sheet, the adhesive layer exhibiting 20 kgf / cm ² or more bonding strength between the both said person, rather conductivity higher than the adhesive, the volume resistivity 10 [Omega · cm or less of the conductive materials layer, do not overlap as divided and arranged in corrosion reinforced concrete assembly is characterized in that by attaching the two. 2. The anticorrosion reinforced concrete assembly according to claim 1, wherein an oxidation resistant metal layer is provided on the surface of the carbon fiber sheet, or the carbon fibers constituting the carbon fiber sheet are covered with an oxidation resistant metal. The carbon fiber sheet, a unidirectional sheet, and said adhesive layer and the conductive material layer, a striped pattern extending in the fiber direction of the carbon fiber sheet was placed in divided so as not to overlap The anticorrosion reinforced concrete assembly according to claim 1 or 2, characterized in that The steel material of the corrosion reinforced concrete assembly according to any one of claims 1 to 3 as a cathode, corrosion methods corrosion reinforced concrete assembly, characterized by passing a carbon fiber sheet as an anode .

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