Cathodic protection method for concrete structures

Abstract

To provide an electrolytic protection method for a concrete structure, which can save labor for construction.SOLUTION: The electrolytic protection method for a concrete structure includes: an electrode installation step A1 for installing electrodes 2, 7 on a surface 5 of an existing concrete structure 1; and a built-up part installation step for installing a built-up part 6 of stripe-like mortar, which has a predetermined width including the electrodes 2, 7, along a length direction of the electrodes 2, 7 on the surface 5 of the existing concrete structure 1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for cathodic protection of a concrete structure. [Background technology]

[0002] Patent Document 1 describes cathodic protection for preventing corrosion of reinforcing bars embedded in concrete structures. This cathodic protection method involves placing a cutting device equipped with a cutting blade on the surface of the concrete structure, moving the cutting device to form a long groove on the surface, and embedding a long cathodic protection electrode in the groove. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4988051 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the cathodic protection method of Patent Document 1, grooves are formed in the surface of the concrete structure and cathodic protection electrodes are installed therein, which makes the construction work time-consuming.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a method for cathodic protection of concrete structures that can reduce the labor required for construction. [Means for solving the problem]

[0006] The present invention is a method for cathodic protection of a concrete structure, comprising: an electrode installation step of attaching an electrode to the surface of an existing concrete structure; and a deposit installation step of installing a mortar deposit on the surface of the existing concrete structure, the deposit having a predetermined width including the electrode and extending in the longitudinal direction of the electrode.

[0007] According to the above-mentioned method for cathodic protection of concrete structures, electrodes are attached to the surface of the existing concrete structure itself in the electrode installation process, so there is no need to form holes or grooves for electrode installation in the existing concrete structure, thereby reducing the amount of work required for construction.Furthermore, the electrode is reliably installed in the mound installation process, as it is provided with a predetermined width including the electrode and a streak-shaped mortar mound that runs along the length of the electrode is installed on the surface of the existing concrete structure.

[0008] The present invention includes a form installation process in which a form that follows the length of the electrode is installed on the surface of the existing concrete structure at intervals of a predetermined width including the electrode, and the deposit installation process can employ a process in which the mortar is deposited along the form installed in the form installation process.

[0009] According to the above-described cathodic protection method for a concrete structure, the mortar banking portion is installed in the banking portion installation step on the form material in the form material installation step, so that the installation of the banking portion is reliable.

[0010] In the present invention, the depositing portion setting step may employ a method in which the mortar is filled between the form materials by dry spraying.

[0011] According to the above-mentioned method for cathodic protection of concrete structures, in the laying section installation process, mortar is filled between the formwork installed in the formwork installation process by dry spraying, so that the mortar in the laying section has no fluidity, has good adhesion to the surface of the existing concrete structure, and is highly durable.

[0012] The present invention includes a caulking installation step of caulking both widthwise sides of the depositing portion installed in the depositing portion installation step with a caulking material.

[0013] According to the above-mentioned method for cathodic protection of concrete structures, in the caulking installation process, caulking material is installed at the corners formed between the surface and the deposit, which provides excellent adhesion of the deposit to the surface and ensures waterproofing, preventing water penetration. [Effects of the Invention]

[0014] According to the cathodic protection method for a concrete structure of the present invention, electrodes are attached to the surface of an existing concrete structure, so no holes or grooves are formed in the surface, thereby reducing the labor required for construction. [Brief explanation of the drawings]

[0015] [Figure 1] 1A and 1B are diagrams illustrating an electrode installation process according to one embodiment of the present invention, in which (a) is a plan view of the state in which the anode is installed on the surface, (b) is a plan view of the state in which the anode and distributor are installed on the surface, and (c) is a cross-sectional view taken along the line B1-B1 of (a). [Figure 2] 10A and 10B are diagrams showing the process of installing the mold material, where (a) is a plan view of the mold material installed on the surface, and (b) is a cross-sectional view taken along the line B2-B2 of (a). [Figure 3] 10A and 10B are diagrams showing the process of installing the depositing part, in which (a) is a plan view of the depositing part sprayed onto the surface, and (b) is a cross-sectional view taken along the line B3-B3 of (a). [Figure 4] 4A and 4B are diagrams showing the removal step, in which (a) is a plan view of the state in which the mold material has been removed from the surface, and (b) is a cross-sectional view taken along the line B4-B4 of (a). [Figure 5] 10A and 10B are diagrams showing the caulking installation process, in which (a) is a plan view of the caulking applied to the surface, and (b) is a cross-sectional view taken along the line B5-B5 of (a). DETAILED DESCRIPTION OF THE INVENTION

[0016] A cathodic protection method for a concrete structure according to one embodiment of the present invention will be described below with reference to Figures 1 to 5. Cathodic protection for a concrete structure (hereinafter referred to as an existing structure) 1 is a method in which an anode 2 installed in the existing structure 1 is electrically connected to another anode 2 by a distributor 7, and reinforcing bars (steel materials) 3 buried inside the existing structure 1 are used as cathodes, thereby generating a potential difference between the anode and cathode to protect the reinforcing bars 3 from corrosion.

[0017] As shown in Figures 5(a) and (b), an electric corrosion protection structure 4 using the construction method of the electric corrosion protection method of this embodiment has a structure in which electrodes covered with mortar deposits 6, i.e., anodes 2 and distributors 7, are laid on the surface of the body, i.e., the surface 5 of the existing structure 1, and caulking material 8 is provided at the corners formed by the surface 5 and the deposits 6.

[0018] The cathodic protection method according to the present embodiment includes the following steps, as shown in FIGS. 1 to 5: (1) An electrode installation process A1 (see FIG. 1 ) of attaching a strip-shaped anode 2 and a distributor 7 to the surface 5 of an existing structure 1; (2) A mold installation process A2 (see FIG. 2 ) in which mold members (backup members in this embodiment) 9 are installed on the surface 5 of the existing structure 1 at intervals of a predetermined width H including the anode 2 and the distributor 7, along the length of the anode 2; (3) A deposit installation process A3 (see FIG. 3 ) in which a mortar deposit 6 is filled on the surface 5 between the molded material 9 by dry spraying; (4) A mold removal process A4 (see FIG. 4 ) in which, after the mortar deposit 6 is filled by dry spraying, the mold 9 is removed while leaving the deposit 6; (5) A caulking installation process A5 (see FIG. 5) in which caulking material 8 is applied to the corner formed by the surface 5 and the application portion 6; It is equipped with:

[0019] The above (1) electrode installation process A1 will now be described in detail. The steps of the electrode installation process A1 include a deposit removal process, a rebar detection process, a reference electrode installation process, an anode installation position determination process, a primer application process, an anode installation process, and a distributor installation process. These processes install the anode 2 and distributor 7 on the surface 5 of the existing structure 1. Each process will be described below. (1)-1 Deposit removal process The deposit removal process involves removing dirt and old paint from the surface 5 of the existing structure 1. For this, a sander scraper or the like is used to remove dirt and unnecessary deposits such as old paint. (1)-2 Rebar detection process In the rebar detection process, the actual positions of the rebars 3 in the existing structure 1 are detected. For this, an RC radar or the like is used. However, if the positions of the rebars 3 in the existing structure 1 are as designed, it is not necessary to use an RC radar or the like. (1)-3 Reference electrode installation process In the reference electrode installation process, the surface 5 of a designated rebar 10 on which a reference electrode (not shown) is to be installed, among the rebars 3 detected in the rebar detection process, is chipped, the designated rebar 10 is exposed, the reference electrode is connected, and the chipped portion 11 is backfilled with mortar. (1)-4 Anode installation position determination process In the anode installation position determination process, a mark is placed at the installation position of the anode 2 among the reinforcing bars 3 detected in the reinforcing bar detection process, in the longitudinal direction of the reinforcing bar 3 relative to the surface 5 (projected onto the surface 5), to determine the position of the anode 2. (1)-5 Primer application process In the primer application step, a primer (not shown) is applied to the surface 5. The primer is applied to make it easier to adhere the deposition portion 6, which will be described later. The primer is applied using a sprayer. Before applying the primer, dust on the surface 5 is also removed using an air blower. (1)-6 Anode installation process In the anode installation process, multiple anodes 2 are attached to the surface 5 at the locations marked out in the anode installation position indexing process (Figs. 1(a) and 1(c)). The anodes 2 are titanium ribbon mesh formed in a strip shape, and therefore have a predetermined width H2. Because the anodes 2 are not yet fixed to the surface 5, plastic nails 12 are used to fix them in place, and the nail heads 12a of the plastic nails 12 are abutted against appropriate positions on the anodes 2, while the nail shafts 12b are driven into the existing structure 1, thereby fixing the anodes 2 to the surface 5 (Fig. 1(c)). (1)-7 Distributor installation process In the distributor installation process, a distributor 7 is attached to the pair of anodes 2 installed in the anode installation process so as to fit along the surface 5. At this time, the distributor 7 is attached so as to be electrically connected to the anodes 2 (FIG. 1(b)). To electrically connect the anodes 2 and the distributor 7, for example, spot welding 7a is used. The distributor 7 is a titanium ribbon mesh formed in a band shape, and therefore has a predetermined width H2. Note that the widths H2 of the anodes 2 and the distributor 7 may differ. Because the distributor 7 is not yet fixed to the surface 5, plastic nails 12 are used to fix them. The nail heads 12a of the plastic nails 12 are abutted against appropriate positions on the distributor 7, and the nail shafts 12b are driven into the existing structure 1 to fix the distributor 7 to the surface 5.

[0020] These steps complete the installation of the strip-shaped anode 2 and distributor 7 on the surface 5 of the existing structure.

[0021] Next, (2) the mold setting process A2 will be described in detail. The mold setting process A2 is a process of setting the mold 9 of the depositing section 6, which will be described later. In this embodiment, a backup material is used as the mold 9. The mold 9 has a rectangular cross section, and is made of polyethylene foam (sponge). The thickness of the mold 9 is set to be greater than the thicknesses of the anode 2 and distributor 7. In this case, the thickness refers to the thickness from the surface 5. The mold setting process A2 is a process that includes a mold placement process and a mold fixing process. (2)-1 Form placement process In the mold material arrangement process, the mold materials 9 are arranged on both widthwise sides of the predetermined width H including the anode 2, i.e., on one widthwise side of the anode 2, at a distance from the anode 2, and on the other widthwise side of the anode 2, at a distance from the anode 2 (FIG. 2(b)). The mold materials 9 are arranged on both widthwise sides of the anode 2, along the length of the anode 2 (FIG. 2(a)). Furthermore, the mold materials 9 are arranged on both widthwise sides of the predetermined width H including the distributor 7, i.e., on one widthwise side of the distributor 7, at a distance from the distributor 7, and on the other widthwise side of the distributor 7, at a distance from the distributor 7. The mold materials 9 are arranged on both widthwise sides of the distributor 7, along the length of the distributor 7 (FIG. 2(a)).

[0022] In this embodiment, the predetermined width H including the anode 2 and distributor 7 is 70 mm, and the mold 9 is placed outside this predetermined width H, with the width H1 of the mold 9 being 20 mm. Since the mold 9 has a rectangular cross section, the height of the inner surface 9a of the mold 9 from the surface 5 is also 20 mm.

[0023] (2)-2 Shape material fixing process Since the mold 9 is not yet fixed to the surface 5, in order to fix the mold 9, concrete nails (or concrete screws) 120 are used to fix the mold 9 to the surface 5 as a mold fixing process (Figure 2(b)).

[0024] These operations complete the form member setting step A2 of setting the form member 9 on the surface 5 of the existing structure.

[0025] Next, (3) the deposit portion filling step A3 will be described in detail. The deposit portion filling step A3 is a step in which mortar deposit portions 6 are sprayed between the formwork 9 by dry spraying (FIGS. 3(a) and 3(b)). The deposit portions 6 in the deposit portion filling step A3 are strip-shaped deposit portions that run along the lengths of the anode 2 and distributor 7, and are laid in the area formed by a predetermined width H and each inner surface 9a (area R in FIG. 2(b)).

[0026] By dry spraying the mortar, the mortar is piled up on the surface 5 to form the deposit 6, covering the anode 2 and distributor 7. Furthermore, the deposit 6 does not flow when laid, and because a primer has been applied to the surface 5 in advance, the deposit 6 and the surface 5 are bonded together. Furthermore, even if the anode 2 and distributor 7 are floating above the surface 5 (FIG. 3(b)), the deposit 6, which is dry sprayed, fills the small gap, allowing the anode 2 and distributor 7 to be aligned with the surface 5. In this embodiment, the height of the deposit 6 is the height of the inner surface 9a of the mold 9, and is therefore 20 mm from the surface 5, which is the design height of the deposit 6.

[0027] These operations complete the deposit filling step A3 in which the deposit 6 is sprayed onto the surface 5 of the existing structure by dry spraying.

[0028] Next, (4) the mold material removal process A4 will be described in detail. The mold material removal process A4 is a process of removing the mold material 9 after the depositing portion 6 has been filled. In this case, the mold material 9 can be removed from the surface 5 by pulling out the concrete nails 120 used in the mold material 9 from the surface 5 (FIGS. 4(a) and 4(b)).

[0029] By this operation, the form material 9 can be removed from the surface 5 of the existing structure, leaving the piled portion 6.

[0030] Next, (5) Caulking Installation Process A5 will be described in detail. Caulking Installation Process A5 is a process in which, after removing the mold material 9, caulking material 8 is applied to the corners formed between the surface 5 and the applied portion 6. Examples of caulking material 8 include epoxy-based, urethane-based, and silicone-based materials. The caulking material 8 is applied to prevent moisture from seeping in between the surface 5 and the applied portion 6.

[0031] Here, the shape of the depositing portion 6 is a rectangular cross section as shown in Figure 4(b), consisting of a widthwise bottom portion provided on the surface 5 side with a predetermined width H, a top portion facing the bottom portion, and outer surfaces 6a on both sides perpendicular to the bottom portion (surface 5). The caulking material 8 functions to prevent moisture from penetrating where the outer surfaces 6a of the depositing portion 6 and the bottom portion meet, in other words, it is a material that fills the joint where the outer surfaces 6a of the depositing portion 6 and the bottom portion meet.

[0032] In this embodiment, the caulking material 8 has a triangular cross section and is formed between the surface 5 on the side of the deposit portion 6 and the entire outer surface 6a (20 mm in size in this embodiment) of the deposit portion 6. However, it is also possible to form the caulking material 8 partway along the outer surface 6a of the deposit portion 6, provided that moisture is prevented from seeping in between the surface 5 and the deposit portion 6.

[0033] These steps complete the caulking installation step A5 of applying the caulking material 8 to the surface 5 of the existing structure.

[0034] Then, the process goes through (1) electrode installation process A1, (2) mold installation process A2, (3) filling process A3, (4) mold removal process A4, and (5) caulking installation process A5 to produce the cathodic protection structure 4 shown in Figure 5(b).

[0035] According to this embodiment, (1) in the electrode installation step A1, the anode 2 and distributor 7 are attached to the surface 5 of the existing structure 1 itself, so there is no need to form installation holes in the existing structure 1 for burying the anode 2 and distributor 7. Such installation holes are usually formed in the surface 5 using an impact drill or by chipping, but this embodiment can omit these steps, which reduces the amount of work required for construction.

[0036] In this embodiment, (2) form material installation process A2 installs form material 9 on the surface 5 of the existing structure, (3) laying portion filling process A3 sprays laying portion 6 onto the surface 5 of the existing structure by dry spraying, and (5) caulking installation process A5 applies caulking material 8 to the surface 5 of the existing structure. Therefore, these processes involve work being performed on the surface 5 of the existing structure 1 itself, which reduces the amount of work required for construction.

[0037] In particular, in (3) deposit portion filling step A3, the deposit portion 6 is sprayed by dry spraying and filled to a predetermined width H including the anode 2 and distributor 7, and a stripe-like deposit portion 6 is formed on the surface 5 of the existing structure 1 along the length of the anode 2 and distributor 7. This ensures that the anode 2 and distributor 7 are securely installed on the surface 5. Furthermore, because the deposit portion 6 is dry sprayed and filled between the molding materials 9, the installation of the deposit portion 6 is secure, and because the deposit portion 6 is dry sprayed and filled between the molding materials 9, the deposit portion 6 does not have fluidity, has good adhesion to the surface 5 of the existing structure 1, and is also highly durable.

[0038] In addition, in (5) caulking installation process A5, by applying caulking material 8 to the corners formed by the surface 5 and the laying portion 6, excellent adhesion of the laying portion 6 to the surface 5 is ensured, and waterproofing is ensured, preventing water penetration into the reinforcing bars 3.

[0039] The present invention is not limited to the above embodiment. In the above embodiment, the mold 9 was used in (2) mold installation step A2. However, the mold 9 is not necessarily required. After (1) electrode installation step A1, the deposit portion 6 may be sprayed by dry spraying without using the mold 9. Even in this case, the deposit portion 6 will be a striped deposit portion 6 along the length of the anode 2 and distributor 7. In such a case, there is no need to remove the mold 9. In (5) caulking installation step A5, caulking material 8 is applied to the corners formed by the surface 5 and the deposit portion 6. In this case, the outer surface 6a of the deposit portion 6 is unlikely to be linear because the mold 9 is not provided, but this can be accommodated with the caulking material 8.

[0040] In the above embodiment, in (2) form material installation step A2, the backup material is the form material 9, but a wooden frame (not shown) may also be used as the form material 9. When using this wooden frame, its cross section may be L-shaped so as to fit along the outer surface 6a of the depositing portion 6.

[0041] In the above embodiment, the surface 5 is the surface of the existing structure 1, but it may also be the surface of a structure that has not been chipped or cut, or the surface of its frame.

[0042] In the above embodiment, the anode 2 and distributor 7 are provided in a strip shape. However, the anode 2 and distributor 7 may also be linear. [Explanation of symbols]

[0043] 1...existing structure, 2...anode, 3...reinforcing bar, 4...electrolytic protection structure, 5...surface, 6...mounting portion, 6a...outer surface, 7...distributor, 8...caulking material, 9...form, 9a...inner surface, 10...specified reinforcing bar, 11...chipping portion, 12...plastic nail, 12a...nail head, 12b...nail shaft, 120...concrete nail, A1...electrode installation process, A2...form installation process, A3...mounting portion filling process, A4...form removal process, A5...caulking installation process, H...specified width, H1...form width, H2...anode width

Claims

[Claim 1] an electrode installation process of attaching strip-shaped electrodes to the surface of the existing concrete structure; a deposit installation step of installing a mortar deposit on the surface of the existing concrete structure, the deposit being provided with a predetermined width including the electrode attached to the surface in the electrode installation step and extending in the longitudinal direction of the electrode; a form installation process for installing a form on one side of the electrode in the width direction along the length of the electrode and spaced apart from the electrode so as to be spaced apart by a predetermined width including the electrode attached to the surface in the electrode installation process, and a form on the other side of the electrode in the width direction along the length of the electrode and spaced apart from the electrode so as to be spaced apart by a predetermined width including the electrode attached to the surface in the electrode installation process, on the surface of the existing concrete structure so that the inner surface of the form on one side of the width direction and the inner surface of the form on the other side of the width direction are perpendicular to the surface, The depositing portion installation step is a step of depositing the mortar by dry spraying along the mold members installed in the mold member installation step, on the surfaces and the electrodes exposed between the mold members on one side in the width direction and the mold members on the other side in the width direction, and between the mold members; The cathodic protection method for a concrete structure includes, after the deposit portion installation step, a form material removal step of removing the form material while leaving the deposit portion installed in the deposit portion installation step.

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