JPS62263985A - Electrolytic protection method for concrete structure - Google Patents

Abstract

PURPOSE:To carry out the electrolytic protection of a structure extending over the air and an electrolyte at low current density by forming an electrically conductive coat on the structure in the air and connecting an electrolytic protector fitted to the structure in the electrolyte to the coat with an electric current sucking material in-between. CONSTITUTION:An electrically conductive coat 1 is fixed on the rear side of the floor of a pier with anchor bolts 2. An electric current sucking material 5 such as a Cu sheet is attached to a metallic structure such as a steel pipe pile 3 or a concrete structure in the upper part of the sea (electrolyte) with an insulating material 4 in-between and the material 5 is connected to the coat 1. A galvanic anode 8 is fitted to the pile 3 in the vicinity of the material 5 with a core metal 9 in-between. Part of electric current for electrolytic protection flowing in the pile 3 in the electrolyte is allowed to flow in reinforcing steel material 10 in the concrete structure in the air through the material 5 and the coat 1. By this method, the electrolytic protection of the steel material 10 in the air can be uniformly carried out over a wide range.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is applicable to concrete structures using reinforcing bars or PC steel as reinforcing steel, such as long bridges and bridges on coastal roads;
Offshore Plan 1 - Concerning cathodic protection methods for forms, quays, piers, wave-dissipating facilities, etc.

[Conventional technology]

Reinforced concrete structures (hereinafter referred to as RC structures)
It has been considered a semi-permanent structure that requires no upkeep or maintenance in addition to its structural sturdiness due to its combination of materials such as concrete and steel. However, in RC structures in the marine environment, a large amount of salt contained in seawater spray and sea breeze comes flying in, and if it adheres to it, it can damage the inside of the concrete.
It has been found that it penetrates and corrodes internal reinforcing steel.

In addition, even in RC structures in the atmospheric environment, the neutralization of concrete is progressing due to the influence of exhaust gas from automobiles and factories, and the reinforcing bars are corroded due to the increase in salt content in concrete due to the use of sea sand. An accident occurred in which cover concrete 1- swelled and fell off, and it was widely reported in the media.

Conventionally, anti-corrosion measures for such RC structures include hot-dip galvanizing the reinforcing bars, or adding anti-rust materials as an admixture when mixing concrete.
Methods such as creating a strong oxide film on reinforcing bars have been implemented, and methods using cathodic protection such as galvanic anode method or external power supply method are used for RC structures in seawater, and For RC structures, overseas literature has shown that cathodic protection is effective by covering the surface of the structure with conductive paint and embedding a platinum wire electrode connected to a DC power supply in order to supply a protective current. has been done.

[Problem that the invention seeks to solve]

However, although the method using zinc plating described above has sufficient corrosion resistance in the presence of a low concentration of salt, there is a great risk that the reinforcing steel will corrode in the presence of a higher concentration of salt or in a location where cracks have been reached. In addition, the method using rust preventive agents can be dangerous if the usage standards are not fully observed, such as pitting corrosion occurring in reinforcing bars if the amount of rust preventive added in Concrete 1 is less than the amount required for corrosion prevention. become. Furthermore, the conventional cathodic protection method has the limitation that it can only be implemented where the power source is available, that is, an external power source method, for structures with r < c in the atmosphere. It must be said that it is extremely uneconomical to install electrodes in seawater and separately in corrosion protection design and construction.

This invention was made in order to solve the above-mentioned problems, which may be related to conventional ones. -1 The purpose of the present invention is to provide concrete-1 which makes it possible to prevent corrosion of reinforcing steel materials for structures, and a method for cathodic protection of structures.

Means for Solving Problem c] In order to achieve this object, the present invention has the following configuration.

That is, the cathodic protection method for concrete structures according to the present invention covers a concrete structure in the atmosphere with a conductive coating, and protects a metal structure or concrete structure continuous to the concrete structure in an electrolyte. A cathodic protection device is attached to the metal structure in the electrolyte, and a current absorption material is installed in the electrolyte at least in the vicinity, and the metal structure in the electrolyte is electrically connected to the current absorption material and the conductive coating. A part of the anticorrosion current flowing into objects or concrete structures is made to flow into the reinforcing steel of the concrete structure in the atmosphere via the current absorption material and conductive coating.

[For production]

In the cathodic protection method configured in this way, the anticorrosion current i due to cathodic protection flows into the metal structure or concrete structure in the electrolyte, and maintains the surface in a good corrosion protection state. On the other hand, a part of the anti-corrosion current i flows into the current absorbing material in the electrolyte, passes through the electric wire, the conductive coating in the atmosphere, and the concrete layer, flows into the reinforcing steel material, and flows onto the surface of the reinforcing steel material.
Provides a uniform potential distribution.

In other words, this invention involves the presence of a galvanic system of electrodes for cathodic protection/current absorption material in the electrolyte, and the reinforcing steel material (Fe) to be protected against corrosion is not directly short-circuited with the conductive coating. By short-circuiting Anno-1 (electrode for cathodic protection) and reinforcing steel material (re), and short-circuiting Ka-1- (current absorption material) and the conductive coating, conductive coating/1? Electrolytic protection is performed by adding galvanic electromotive force to e-system electromotive force.

Furthermore, since the conductive coating acts as a wide current distribution electrode, the anode current density is low and the degree of wear of the conductive coating is extremely low.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 and FIG. 2 are schematic vertical cross-sectional views of a pier steel pile and a bridge concrete pile, respectively.

In Figure 1, a conductive coating 1, for example a plurality of zinc sheets (50 x 1,000 xl), is placed on the back side of the pier deck.
are covered and fixed with anchor ports 2 respectively. As the conductive coating 1, in addition to a zinc sheet, zinc solvent, aluminum spraying, conductive paint, conductive concrete I, conductive resin sheet, aluminum sheet, etc. can be used.

Next, a current absorbing material 5, such as a copper sheet, is attached to the steel pipe pile 3 in the upper part of the sea via an insulating material 4 such as petrolatum tape using a fastener such as a poldona knot.

At this time, it is not always necessary that the entire current absorption material 5 is submerged in the electrolyte. Pick up this current.

Further, the current absorbing material 5 is connected to the covering 1 by an electric wire housed in a vinyl tube 6. This vinyl pipe 6 is fixed to the steel pipe pile 3 with the hinges 1-7.

Further, a galvanic anode 8 made of aluminum alloy, zinc alloy, magnesium alloy, etc. is attached to the steel pipe pile l near the current absorbing member 5 by welding its steel core 9. It goes without saying that, in addition to the current galvanic anode type cathodic protection device, an external power source type cathodic protection device has the same effect.

Note that it is effective to cover the outside of the conductive coating 1 with an exterior material 11 such as fiber-reinforced plastic to strengthen it.

In Figure 2, concrete above the high tide level - pile 12
A zinc sear 1-1 is attached to the copper sear 1-1, and a hollow saw 1-5 is attached to the outside thereof, and the copper sear 1-1 is immersed in the sea so that the lower end thereof is at least at the average tide level.

On the other hand, a galvanic anode 8, which has been brought into electrical contact with a reinforcing steel material such as a reinforcing bar, is removed from the concrete pit in the sea by means of an anchor hole 2. Note that 13 is a hole for potential side running.

Furthermore, it is effective to interpose a hackfill material between the conductive coating 1 and the concrete layer.

〔Effect of the invention〕

As explained above, according to the cathodic protection method of this invention,
Since the conductive coating acts as a distributed electrode for cathodic protection and as a shield from the atmosphere, the reinforcing steel material in the atmosphere can be uniformly protected from corrosion over a wide range.

Therefore, for concrete structures exposed to the atmosphere, by simply applying electrolytic protection to the reinforcing steel materials or steel pipe piles in the electrolyte that are connected to them, the effect of electrolytic corrosion can be obtained consistently to the reinforcing steel materials in the atmosphere. Installation is only required in an electrolyte, and cathodic protection in the atmosphere is possible in areas without power supply.

Furthermore, since oxygen and the like are blocked by the concrete layer and the conductive coating, the corrosion protection current density of the reinforcing steel material is significantly reduced.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic cross-sectional views showing one embodiment of the present invention. ■ --- Conductive covering 3 Steel pipe pile 5 - Current absorption material 8 - Galvanic anode 10? ! strong steel moon

Claims (2)

[Claims] (1) A concrete structure in the atmosphere is coated with a conductive coating, and a cathodic protection device is installed on a metal structure or concrete structure that is continuous with the concrete structure in an electrolyte, and at least By installing a current absorption material in the electrolyte and electrically connecting the current absorption material and the conductive coating, a part of the anticorrosion current flowing into the metal structure or concrete structure in the electrolyte can be absorbed. A cathodic protection method for concrete structures characterized by allowing current to flow into the reinforcing steel of concrete structures in the atmosphere via an electrically conductive coating. (2) The cathodic protection method for concrete structures according to claim 1, wherein the current absorbing material has a higher natural potential than the conductive coating.