JPH0665936A - Retaining of reinforced concrete structure - Google Patents

Abstract

PURPOSE:To form an anti-corrosive film even on side faces of a structure above sea level, by stretching a water-retaining member on the exposed part above the submerged face of a reinforced concrete structure in the sea and supplying an electrolytic liquid into the water-retaining member and arranging the anode to get in contact with the member and further, conducting direct currents by using the reinforcing rods of the structure as a cathode. CONSTITUTION:Sea water S is sprinkled on a water-retaining member 13 from nozzles 17 by driving a pump 15 and direct currents are conducted from a DC source device 19 to the electrode 14 and the reinforcing rods 12 in the concrete structure 11. Then calcium or the like in the sea water S included in the water-retaining member 13 is extracted on the surface of the structure 11 as an electrodeposit. In this way, the durability of the side face near the sea level can be increased in the reinforced concrete structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for protecting a reinforced concrete structure, and more particularly to filling voids in concrete in the air, including cracks in a reinforced concrete structure such as a pier or a pier pier, The present invention relates to a method for protecting a reinforced concrete structure, in which the concrete itself is densified and its durability is improved.

[0002]

2. Description of the Related Art Since concrete is porous and easily absorbs water and allows water to pass through, when reinforcing bars are reinforced concrete, the reinforcing bars are corroded, their strength decreases and cracks occur in the concrete layer. , The strength of this concrete layer will also be reduced.

In particular, when this reinforced concrete structure is a pier of a quay or a jetty, seawater will invade the concrete layer, resulting in a remarkable decrease in strength.
In order to solve such a problem, the applicants have previously proposed to repair such a reinforced concrete structure by an electrodeposition method. That is, as shown in FIG. 5, the electrode 1 arranged in the sea and the reinforcing bar 3 of the concrete structure 2 are connected by a wiring 5 having a DC power supply device 4, and the electrode 1 is used as an anode and the reinforcing bar 3 is used as a cathode. For example, when a direct current having a current density of about 0.2 to 0.5 mA / cm ² is applied, alkaline earth metal components such as Ca ions and Mg ions dissolved in seawater are deposited on the seawater immersed surface 6. Electrodeposit (CaCO ₃ , Mg (OH)
₂ ) to form an anticorrosion coating 7 (Japanese Patent Application Laid-Open No. S60-12035).
61-198673).

[0004]

However, in such a reinforced concrete structure, there is a tendency that corrosion and cracks occur remarkably particularly in the tidal part and the splashed part where drying and soaking in seawater are repeated due to the tidal period. It is in. However, in the method for protecting reinforced concrete as described above, since seawater is used as the electrolytic solution, it is possible to form an anticorrosion coating only under the immersion surface, and it is impossible to sufficiently protect the reinforced concrete structure. was there.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, in which a water retention material is stretched over the seawater-immersed surface of a reinforced concrete structure,
An electrode is placed in contact with this water retaining material, and while supplying and impregnating an electrolyte solution to the water retaining material, a method for protecting a reinforced concrete structure in which a direct current is caused to flow by using an electrode as an anode and a reinforcing rod of the reinforced concrete structure as a cathode Is intended to be provided.

[0006]

[Operation] Seawater supplied to the water retention material, such as Ca ionizer
Electrolyte solutions such as artificial seawater and cement milk containing a large amount of Mg ions are impregnated in this water retention material and held by direct current, resulting in alkalis such as calcium (Ca) and magnesium (Mg) dissolved in this electrolyte solution. Electrodeposits composed of earth metal components are deposited on voids (pores) and cracks in the concrete layer, as well as on the surface. That is, a protective film is formed.

[0007]

[Embodiment] An embodiment of a method for protecting a reinforced concrete structure according to the present invention will be described below with reference to FIGS. 1 to 4. In FIG. 1 and FIG. 2, 11 is a concrete structure containing a reinforcing bar 12, and a water retaining material 13 made of glass wool, mortar, plastic net or other woven fabric is provided on the side surface and on the sea surface WL. It is stretched with bolts, bands, etc. and contacts the surface of this water retention material 13
14 are arranged.

This electrode material is preferably lightweight and excellent in water permeability and flexibility. For example, titanium mesh electrode material, carbon cloth fiber, or ordinary wire net or plastic net may be coated with a conductive paint. Anything is fine. Then, by driving a water supply means such as a pump 15, seawater S as an electrolytic solution is sprinkled and supplied from the pipe 16 and the nozzle 17 to the water retaining material 13. Then, the electrode 14 is used as an anode and the reinforcing bar 12 is used as a cathode, and is connected to a DC power supply device 19 by a wiring 18 so that a DC current can flow.

In the electrolysis circuit having the above construction, when the pump 15 is driven to spray the seawater S from the nozzle 17 onto the water retaining material 13, and a direct current is passed from the DC power supply device 19 between the electrode 14 and the reinforcing bar 12, the water retaining material is Calcium or the like in the seawater S contained in 13 becomes an electrodeposit and deposits on the surface of the concrete structure 11. In this case, it is preferable to replenish the seawater S by the pump 15 so that the seawater S in the water retaining material 13 will not be lost due to drying or the like, and to control the current density of the direct current to be 40 to 400 mA / ft ² .

FIG. 3 shows experimental data showing the relationship between the current density and the chemical composition of the electrodeposition product. As shown in this data, the substance deposited by electrolysis when the current density is 40 mA / ft ² or less. Will be porous and crystalline. On the other hand, 40
At 0 mA / ft ^{2 and} above, the substances deposited by electrolysis are amorphous and easily disintegrated. Current densities that give effective coatings are 40-400, best current densities are 50-30
It is 0 mA / ft ² . It is better to control the direct current in consideration of such experimental results.

When the current density is low, the calcium content is high,
On the contrary, it has been confirmed that the amount of magnesium is reduced. Such an electrodeposit becomes crystalline and porous,
As a result, ventilation and water permeability become large, and it is not suitable as a protective film. On the other hand, when the current density is high, the electrodeposit is amorphous and easily disintegrates, and is not suitable as a protective film.

FIG. 4 shows another embodiment. A water retaining material 13 is stretched on the side surface of a reinforced concrete structure 11, and an electrode 14 is arranged so as to contact the water retaining material 13. A waterproof sheet 20 such as a rubber sheet or a vinyl sheet is attached so as to cover the electrode 14. The seawater S is supplied from the pump 15 into the waterproof sheet 20. In this case, the seawater S in the water retaining material 13 can be retained for a relatively long time by the action of the waterproof sheet 20. As a result, it is possible to form a sufficient electrodeposit even with intermittent water supply.

Although seawater S is used as the electrolytic solution in the above embodiments, artificial seawater or artificial electrolytic solution such as cement milk may be used. Further, the water retaining material 13, the electrode 14 and the like may be unitized in advance and attached to the side surface of the reinforced concrete structure 11 with bolts, bands or the like.

[0014]

The method for protecting a reinforced concrete structure according to the present invention comprises a water retaining material stretched over the seawater-immersed surface of the reinforced concrete structure, and an electrode is placed in contact with the water retaining material. And an electrode is used as an anode and a reinforcing bar of the reinforced concrete structure is used as a cathode to apply a direct current to form an electrodeposition coating.

Therefore, it is possible to form a protective film by an electrodeposit on the side surface of the reinforced concrete structure on the sea surface, and as a result, it is possible to improve the durability of the side surface near the sea surface where corrosion and cracking are particularly remarkable. There is an effect.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a concrete structure in an embodiment of a method for protecting a reinforced concrete structure according to the present invention.

FIG. 2 is a front view of a concrete structure in an embodiment of a method for protecting a reinforced concrete structure according to the present invention.

FIG. 3 is data showing a relationship between a current density of a concrete structure and an electrodeposit in an embodiment of the method for protecting a reinforced concrete structure according to the present invention.

FIG. 4 is a cross-sectional view of a reinforced concrete structure according to another embodiment.

FIG. 5 is an explanatory diagram of a conventional method for protecting a reinforced concrete structure.

[Explanation of symbols]

1, 14 Electrode 2, 11 Concrete structure 3,
12 Reinforcing bar 4, 19 DC power supply device 6 Seawater immersion surface 7 Anticorrosion coating 13 Water retaining material 15 Pump 20 Waterproof sheet.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fukute Tsutomu 3-1-1 Nagase, Yokosuka City, Kanagawa Prefecture, Port Research Institute of the Ministry of Transport (72) Masami Abe 3-1-1, Nagase, Yokosuka City, Kanagawa Prefecture (72) Inventor, Yutaka Yokota, 2109, Yashimanishimachi, Takamatsu City, Kagawa 8 Shikoku Research Institute, Inc. (72) Harutoshi Sasaki, 5-6-4 Tsukiji, Chuo-ku, Tokyo Mitsui Shipbuilding Co., Ltd.

Claims (1)

[Claims] 1. A water retaining material is stretched in the air above the seawater immersion surface of a reinforced concrete structure, an electrode is arranged in contact with this water retaining material, an electrolytic solution is supplied to the water retaining material, and the electrode serves as an anode. A method for protecting a reinforced concrete structure, characterized in that a direct current is caused to flow using the reinforcing bar of the reinforced concrete structure as a cathode.