JP2017181363A - Backfill structure of galvanic anode and generation method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backfill structure of galvanic anode capable of extending the service life of a galvanic anode, and a generation method of the backfill used therefor.SOLUTION: A backfill structure 4 of a galvanic anode which includes: a liquid retaining member 5 of a porous material covering galvanic anode 2; and an electrolyte solution impregnated in the liquid retaining member 5. The liquid retaining member 5 contains powdery anode passivation suppressor 7, 7...of an amount exceeding the solubility of the electrolyte solution.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a backfill structure of an galvanic anode used for cathodic protection and a method for producing the same.

  In the case of reinforced concrete structures, the internal rebars corrode due to the neutralization of the concrete, the salt content in the concrete material, the incoming salt content from the outside or the effects of anti-freezing materials (salt damage), leading to deterioration of the concrete There is.

  Therefore, to prevent corrosion of such reinforcing bars, an galvanic anode made of zinc, aluminum, etc., which has a lower oxidation-reduction potential than that of the reinforcing bars, is installed on the concrete surface or inside the concrete. A corrosion-inhibiting structure that electrically connects the steel, creates a potential difference between the galvanic anode and the internal steel, and prevents corrosion of the internal steel by supplying anticorrosion current to the internal steel. It is known (see, for example, Patent Document 1).

  In addition, this type of corrosion-inhibiting structure includes a backfill made by impregnating an electrolyte solution into a liquid retaining member made of a porous material, and surrounds the current-carrying anode with this backfill, and creates a gap between the current-carrying anode and concrete. There is also known a technique in which the electrode potential of the galvanic anode is stabilized with an electrolyte solution to prevent local dissolution of the galvanic anode (for example, see Patent Document 1).

  In this corrosion-inhibiting structure, an anode atom such as a zinc atom forms a complex ion with one Na ion (or Li ion) and four OH ions in the electrolyte solution, and elutes into the electrolyte solution. Stabilized.

  Moreover, when a passive film is formed on the anode, the anticorrosion effect is reduced. To suppress such passivation of the anode, an electrolyte such as sodium hydroxide (NaOH) or lithium hydroxide (LiOH) is used. It is known that the use of a solution is effective, and in order to suppress passivation, it is desirable that the pH of the electrolyte solution be high, for example, in the case of a zinc anode, the pH should be 13.3 or higher. It is also known that the durability of the anode is improved when the initial pH is high, for example, 13.5 to 14.0 or more.

Japanese Patent No. 3099830

  However, in the conventional techniques as described above, the volume of the electrolyte solution that can be impregnated in the liquid retaining member is limited, and complex ions must be formed in order for the anode atoms to elute into the electrolyte solution. Since four OH ions are consumed, there is a problem that the OH ions in the electrolyte solution decrease with time, and the performance of the galvanic anode decreases accordingly.

  Therefore, in view of such a conventional problem, the present invention has been made for the purpose of providing a backfill structure of a galvanic anode capable of extending the life of the galvanic anode and a method of generating a backfill used therefor. Is.

  The feature of the invention according to claim 1 for solving the conventional problems as described above is that a liquid retaining member made of a porous material covering the electroplating anode and an electrolyte solution retained in the liquid retaining member are provided. In the backfill structure of the galvanic anode, the backfill structure of the galvanic anode in which the liquid retaining member contains a powdery anode passivation suppression material in an amount exceeding the solubility of the electrolyte solution. It is in.

  According to a second aspect of the present invention, there is provided a backfill generation method for use in the backfill structure of the galvanic anode according to the first aspect, wherein the fine particle porous material is coated with a powdery anode. By adding a mobilization inhibitor and kneading it with water, the electrolyte solution is retained in the porous material, and the anode passivation passivation material in excess of the solubility of the electrolyte solution is solidified. It is to make it contain in the state of.

  As described above, the backfill structure of the galvanic anode according to the present invention includes a liquid retaining member made of a porous material that covers the galvanic anode, and an electrolyte solution retained in the liquid retaining member. In the backfill structure of the electroanode, the liquid retaining member contains a powdery anode passivation suppression material in an amount exceeding the solubility of the electrolyte solution. Even if the hydroxide ions in the solution decrease, the anode passivation suppression member contained in the liquid retaining member elutes into the solution, so that the hydroxide ions are supplied. Can be improved.

  Further, in the present invention, a powdery anode passivation suppressing material is added to a fine particle porous material, and water is added to the kneaded material to knead, thereby holding the electrolyte solution in the porous material. The anode passivating suppression material in a solid state is contained in a solid state by containing the anode passivation suppression material in an amount exceeding the solubility of the electrolyte solution. Can be made.

It is a schematic sectional drawing which shows an example of the electric corrosion suppression method using the backfill structure of the galvanic anode which concerns on this invention. It is the graph which compared the off electric potential with respect to the electricity supply time in the backfill structure which concerns on this invention, and a prior art in the test same as the above. It is the graph which compared the off electric potential with respect to the electricity supply time in the backfill structure which concerns on this invention, and a prior art in the test same as the above.

  Next, embodiments of the backfill structure of the galvanic anode according to the present invention will be described based on the examples shown in FIGS.

  FIG. 1 shows an example of a method for inhibiting electric corrosion using a backfill structure according to the present invention, in which an galvanic anode 2 installed in concrete 1 and an internal steel material 3 such as a reinforcing bar are electrically connected to each other. By utilizing the potential difference between the electric anode 2 and the internal steel material 3, an anticorrosion current is supplied to the internal steel material 3 to suppress corrosion of the internal steel material 3.

  The backfill structure 4 includes a liquid retaining member 5 that surrounds the galvanic anode 2 and an electrolyte solution impregnated in the liquid retaining member 5, and the electrolyte solution impregnated in the liquid retaining member 5 is in contact with the galvanic anode 2. As a result, the galvanic anode 2 is corroded, and the generation of a passive film on the galvanic anode 2 is suppressed.

  The galvanic anode 2 is formed of a metal such as zinc or aluminum having a low oxidation-reduction potential with respect to the internal steel material 3 such as a reinforcing bar, and is electrically connected to the internal steel material 3 such as a reinforcing bar via a lead wire 6 or the like. It is like that.

  The electrolyte solution is a sodium hydroxide solution, a lithium hydroxide solution or the like adjusted to a pH of 13.5 or more, and an electrolyte having an effect of suppressing the passivation of the galvanic anode 2 is dissolved in a solvent such as water. It is in solution.

  The liquid retaining member 5 is made of a porous material such as cement mortar, bentonite, gypsum, and the like so that an aqueous solution can be impregnated and retained in the gap.

  The porous material is not limited to the examples given above, and may be any porous material that can be impregnated and retained by an electrolyte solution, and may be composed of, for example, a phenol continuous foaming resin.

  In addition, the liquid retaining member 5 has an anode passivation made of an electrolyte similar to the electrolyte used in an electrolyte solution such as powdered (solid) sodium hydroxide or lithium hydroxide in an amount exceeding the solubility of the electrolyte solution. The anti-oxidation materials 7, 7... Are contained in an evenly dispersed state.

  In order to produce this backfill, a predetermined amount of powdered anode passivation suppression material 7, 7... Is added to a predetermined amount of fine-particle porous material, and water is added thereto and kneaded. As a result, the porous material exhibits a certain shape retaining property, and the anode mobilization suppressing material 7 is dissolved in the water retained in the gap between the porous materials to form an electrolyte solution, and the amount exceeding the solubility Of anode passivating suppression materials 7, 7... Are uniformly dispersed in a solid state.

  Then, a liquid holding member made of a porous material is molded, cured in that state and cured, and then impregnated with an electrolyte solution as necessary to adjust the electrolyte concentration and pH.

  In the backfill structure 4 configured as described above, the liquid retention member 5 contains the anode passivation suppression materials 7, 7... In an amount equal to or higher than the solubility of the electrolyte solution in the liquid retention member 5 in the initial stage. Therefore, the electrolyte solution is in a state where a certain amount or more of the electrolyte cannot be dissolved, that is, in a saturated state, and the anode passivation suppression material 7, 7. The liquid holding member 5 is held in an ionic crystal state.

  Next, when the galvanic anode 2 and the internal steel material 3 such as a reinforcing bar are electrically connected to form a corrosion inhibiting circuit, the anode atom is composed of one cation such as sodium ion and four hydroxide ions and complex ions. And is eluted in the solution, and the hydroxide ions in the electrolyte solution decrease with time.

  On the other hand, since the liquid retaining member 5 contains anode passivation suppression materials 7, 7... In the form of ionic crystals, the anode passivation suppression materials 7, 7,. .. elutes into the electrolyte solution, and hydroxide ions are supplied, so that the anode passivation inhibitor concentration in the electrolyte solution is kept constant over the long term.

  2 and 3 are graphs comparing the relationship between the number of days elapsed from the start of energization when energizing the galvanic anode 2 and the off-electricity and instant-off potential of the galvanic anode (zinc).

  In the case of using the conventional backfill structure, as shown in FIGS. 3 and 4, the off-potential and the instant-off potential are rapidly increased shortly after the start of energization, whereas in the backfill structure 4 according to the present invention, A rapid increase in the off-potential and instant off-potential is suppressed over a long period of time, and a stable state can be maintained.

  In the above-described embodiment, an example in which the backfill structure according to the present invention is applied to the corrosion prevention of the internal steel material of the concrete structure has been described. However, the internal steel material is not limited to a reinforcing bar, and may be, for example, a PC steel wire. It can also be applied to a backfill for an galvanic anode attached to the outside of the subject to be protected.

DESCRIPTION OF SYMBOLS 1 Concrete 2 Current-flow anode 3 Internal steel material 4 Backfill structure 5 Liquid retention member 6 Lead wire 7 Anode passivation suppression material

Claims (2)

In a backfill structure of a fluid-electric anode comprising a liquid-holding member made of a porous material that covers the current-carrying anode, and an electrolyte solution held in the liquid-holding member,
The backfill structure for an galvanic anode, wherein the liquid retaining member contains a powdery anode passivation suppressing material in an amount exceeding the solubility of the electrolyte solution. A method for producing a backfill for use in the backfill structure of a galvanic anode according to claim 1,
By adding a powdery anode passivation suppression material to a fine particle porous material and kneading it with water, the electrolyte solution is retained in the porous material, and the solubility of the electrolyte solution A method for producing a backfill, comprising the step of containing the anode passivation suppressing material in a solid state in excess of.

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