JP4014285B2 - Destruction method for reinforced concrete structures - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for destroying a reinforced concrete structure.
[0002]
[Prior art]
Conventionally, when destroying reinforced concrete structures, a method of applying mechanical impact from the outside using a breaker or steel ball is generally used. It sometimes caused trouble.
Therefore, as a method for destroying a reinforced concrete structure that does not depend on such a mechanical impact, for example, Japanese Patent Application Laid-Open No. 59-120257 and Japanese Patent Application Laid-Open No. 60-55169 disclose a hydrated expansive crushing agent in a concrete crushing part. A method for filling a drilled hole is disclosed. These are those in which water is added to a hydrated expansible crushing agent mainly composed of CaO to cause volume expansion, and concrete is crushed by the expansion pressure, but pores are formed by a chemical reaction between CaO and water. Since the internal temperature rises rapidly, the internal pressure of the hole increases and the crushing agent may be ejected from the hole. In addition, since it is difficult to control the chemical reaction rate, there is a risk that the worker may be damaged by an unexpected ejection of the crushing agent.
[0003]
On the other hand, as a method for destroying other reinforced concrete structures that do not depend on mechanical impact, for example, in Japanese Patent Laid-Open No. 52-101835 and Japanese Patent Laid-Open No. 52-107132, a reinforcing bar in reinforced concrete is connected to a positive terminal of a DC power source. At the same time, a cathode electrode made of iron, nickel, copper, or an alloy thereof embedded in the concrete is connected to the negative terminal of the DC power supply, and a direct current is applied to oxidize and expand the reinforcing bar to crush the reinforced concrete. There are disclosed a method and a method of crushing reinforced concrete by impregnating concrete with NaCl or CaCl ₂ as an oxidation promoter and then applying a direct current between the reinforcing bar and the cathode electrode to oxidize and expand the reinforcing bar. Japanese Laid-Open Patent Publication No. 9-256649 discloses a method for dismantling a reinforced concrete structure by covering a concrete plate with a cathode plate mixed with an oxidation promoter and oxidizing and expanding the reinforcing bar through a direct current on the reinforcing bar. Yes.
[0004]
[Problems to be solved by the invention]
The concrete destruction method that oxidizes and expands these reinforcing bars has the advantage that the rate of concrete destruction can be controlled because the corrosion amount of the reinforcing bars increases in proportion to the applied current, but the concrete is impregnated with an oxidation accelerator. The work to be carried out is complicated and takes a long time, and even when partial disassembly is attempted, there is a drawback in that the oxidation accelerator penetrates even into a portion that is not disassembled and corrodes the reinforcing bars. Also, in the method of covering the concrete surface with a cathode plate mixed with an oxidation accelerator, the entire surface of the cathode plate must be adhered to the concrete surface, so it must be fixed with a number of concrete anchor bolts or the like. In addition, after corroding the reinforcing bar, there is a drawback that the work becomes complicated, such as the concrete cannot be crushed unless the cathode plate is first removed. Furthermore, in the method of crushing reinforced concrete by energizing the reinforcing bars by energizing these conventional direct currents, it is necessary to rely only on the lifting force of the concrete due to the expansion of the reinforcing bars, so the interval between the embedded reinforcing bars is wide, If the cover of the concrete is thick, there is a drawback that a sufficient crushing force cannot be obtained and it takes a long time to destroy the concrete structure.
[0005]
The present invention solves such problems in the prior art, the work is simple and safe, the control of the breaking force and breaking speed (breaking time) is easy, and the reinforced concrete structure is also suitable for partial breakage. It aims at providing the destruction method of.
[0006]
[Means for Solving the Problems]
As a result of repeated researches to solve the above problems, the present inventors connected the reinforcing bar in the concrete to the positive electrode of the DC power supply device, and caused the reinforcing bar to oxidize, corrode and expand by passing a DC current. If a metal body that causes corrosion is buried as a cathode and connected to the negative electrode of the DC power supply device, these metals also expand due to alkali corrosion. It was found that pressure was applied due to corrosion and expansion of the metal body that causes alkali corrosion embedded in concrete, and even if the interval between embedded rebars is wide or the concrete cover is thick, it can be easily crushed.
In addition, simply burying a metal body that causes alkali corrosion in concrete has high electrical contact resistance between the concrete and the metal body that causes alkali corrosion, and the metal body that causes alkali corrosion may not corrode or expand sufficiently. In such cases, a mixture of at least one of sodium sulfate, sodium chloride or clay and water, or a backfill such as mortar is interposed between the concrete and the metal body causing alkali corrosion. It is preferable to improve the electrical contact.
In addition, the backfill has the effect of effectively transmitting the pressure caused by the corrosion and expansion of the metal body to the concrete. However, if the corrosion product of the metal body or the backfill that causes alkaline corrosion protrudes from the concrete, the backfill will corrode and expand. In such a case, it is preferable to seal a portion where the corrosion product or the like may protrude from the concrete using a sealing material.
[0007]
The present invention has been made on the basis of such knowledge, and (1) a metal which connects a reinforcing bar of a reinforced concrete structure to a positive electrode of a DC power supply device, and also causes a hole in the reinforced concrete structure to cause alkaline corrosion. A concrete body is destroyed by inserting a body, connecting the metal body that generates alkali corrosion to the negative electrode of the DC power supply device, and corroding and expanding the metal body that generates reinforcing bars and alkali corrosion through a direct current. Method of destroying reinforced concrete structure, (2) Reinforcing the reinforced concrete structure with a positive electrode of a DC power supply unit, making a hole in the reinforced concrete structure, and backfilling the metal body that causes alkali corrosion in the hole The metal body that causes alkali corrosion is connected to the negative electrode of the DC power supply device, and the DC power supply is inserted. A method for destroying reinforced concrete structures characterized by destroying concrete by corroding and expanding rebars and metal bodies that cause alkali corrosion, (3) Metals that cause alkali corrosion in holes drilled in reinforced concrete structures The method for destroying a reinforced concrete structure according to (1) or (2), wherein the body or the metal body that causes alkali corrosion and the backfill are inserted, and then the entrance of the hole is sealed with a sealing material, And (4) the metal body causing alkaline corrosion is at least one selected from the group consisting of metals of zinc, magnesium and aluminum and alloys based on one or more of these metals. The method for destroying a reinforced concrete structure according to any one of the above (1) to (3).
[0008]
The metal body that causes alkali corrosion used in the present invention is a metal body that causes corrosion in an alkaline region. Examples thereof include zinc, magnesium, aluminum, cadmium, indium, tin, gallium, zirconium, beryllium, and the like. Examples of alloys based on one or more of the above include zinc, magnesium, or aluminum when considering the corrosiveness, electrical conductivity, safety to human body, and economic efficiency when acting as a cathode in concrete. Alternatively, an alloy based on zinc, magnesium, or aluminum is particularly preferable as the metal body causing alkali corrosion used in the present invention.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing an example of a state in which the present invention is applied to a reinforced concrete structure, and FIG. 2 is a view showing the surface of the concrete structure after the reinforcing bars and a metal body causing alkali corrosion are corroded and expanded. It is. In FIG. 1, 1 is a reinforcing bar and 2 is concrete. When the present invention is applied to this reinforced concrete structure, a part of the concrete 2 is hung out to expose the rebar 1 and connect the lead wire 3a. Separately, after drilling the concrete 2 as appropriate using a concrete drill or the like, and filling the hole 4 with the backfill 10, the metal body is made of zinc, magnesium, aluminum, or an alloy thereof, and the like that causes alkali corrosion. 5 is inserted, and the lead wire 3b is connected to the metal body 5 which causes this alkali corrosion. Further, since corrosion products and backfill of the metal body 5 may protrude from the entrance of the hole 4 to the concrete surface, the entrance of the hole 4 is sealed with a sealing material 11 such as a mortar or a metal cap. The number of holes 4 into which the metal body 5 causing alkali corrosion is inserted, the drilling position, the hole diameter, the depth of the hole, and the like can be appropriately set depending on the structure of the reinforced concrete structure to be destroyed, the size and shape of the broken part, etc. Good.
[0010]
When the lead wire 3a is connected to the positive electrode of the DC power supply device 6 and the lead wire 3b is connected to the negative electrode and a direct current is passed, the reinforcing bar 1 becomes an anode and is oxidized and corroded. Thus, for example, AlO ₂ ⁻ and HZnO ₂ ²⁻ ions are produced and corroded in an alkaline environment.
Since this oxidized, corroded rebar 1 and alkali-corroded metal body 5 accumulate corrosion products on the surface, as shown in FIG. 2, concrete 2 has cracks 7 due to these expansion pressures. As it occurs, concrete can be easily destroyed.
In each of these embodiments, an example in which a backfill and a sealing material are used has been shown. However, depending on the destructive conditions, it is possible to use either one or not.
[0011]
【Example】
Next, the present invention will be described based on the drawings of the prior art and the examples.
As shown in FIG. 3, reinforced concrete specimens 8 having a vertical and horizontal length of 1.0 m and a thickness of 20 cm with a concrete cover depth of 5 cm are assembled by assembling three reinforcing bars 1 of different diameter steel bars with a diameter of 13 mm at intervals of 20 cm. A backfill 10 in which a hole 4 having a diameter of 32 mm and a depth of 120 mm is vertically drilled from the concrete surface one by one between the reinforcing bar grids, and then mixed with mirabilite, sodium chloride, clay and water in the hole 4. Filled.
Then, these specimens 8 were raised vertically, the lead wire 3a was connected to the exposed part of the reinforcing bar 1, and it connected to the positive electrode of the DC power supply device 6, and the reinforcing bar 1 was used as an anode.
[0012]
(Comparative example by conventional method)
After inserting a steel rod having a diameter of 25.4 mm and a length of 10 cm into the hole 4 of one of the two specimens 8 connected to the lead wire 3b, the inlet of the hole 4 was sealed with mortar, The lead wires 3b were respectively connected to the negative electrode of the DC power supply device 6 and the steel rod was used as the cathode 9.
As a result of adjusting the output current from the DC power source device 6 to 2A in this state and energizing, cracks started to appear immediately above the reinforcing bar lattice after about 2 hours and 35 minutes from the start of energization. About 3 hours and 40 minutes after the start. When the concrete cover part of specimen 8 was lightly struck with a hammer, the concrete cover part around the crack was floating, but the other concrete cover part was not completely lifted. Even if I hit it, it didn't come off.
[0013]
(Example)
In the hole 4 of the other specimen 8, an aluminum alloy rod having the same dimensions as the steel rod used in the comparative example with the lead wire 3b (zinc: 5 wt%, indium: 0.02 wt%, balance: aluminum) After that, the inlet of the hole 4 was sealed with mortar, the lead wires 3b were connected to the negative electrode of the DC power supply device 6 and the aluminum alloy rod was used as the cathode 9.
As in the comparative example, the output current from the DC power supply device 6 was adjusted to 2 A and energized. As a result, after about 2 hours, a crack of up to about 10 cm from the hole 4 of the specimen with the aluminum alloy rod as the cathode 9 occurred. It extended radially, and after about 2 hours and 20 minutes, it was connected to a crack just above the reinforcing bar lattice, so the current supply was stopped. When the concrete cover part of the specimen 8 was lightly struck with a hammer, the entire concrete cover part was completely lifted and peeled off as small fragments along the crack.
[0014]
【The invention's effect】
As described above, the method of the present invention connects the positive electrode of a DC power supply device to a reinforcing bar of a reinforced concrete structure, and also applies the DC power supply device to a metal body that causes alkali corrosion inserted into a hole drilled in a concrete fracture location. In addition to being able to control the destruction rate of the concrete with the amount of electricity applied, both the reinforcing bars and the metal bodies that cause alkaline corrosion corrode and expand, so that the concrete surface is applied to the concrete surface. Since innumerable cracks can be generated, there is an excellent effect that the concrete can be destroyed easily and safely faster than the prior art.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an example of a state in which the present invention is applied to a reinforced concrete structure.
FIG. 2 is a view showing the surface of a concrete structure after corroding and expanding a reinforcing bar and a metal body that causes alkali corrosion.
FIG. 3 is an overhead view showing a conventional example and an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Reinforcement 2 Concrete 3a, 3b Lead wire 4 Hole 5 Metal body which produces alkali corrosion 6 DC power supply device 7 Crack 8 Concrete specimen 9 Cathode 10 Backfill 11 Sealing material

Claims (4)

The rebar of the reinforced concrete structure is connected to the positive electrode of the DC power supply device, and a metal body that causes alkali corrosion is inserted by drilling a hole in the reinforced concrete structure. A method for destroying a reinforced concrete structure, wherein the concrete is destroyed by corroding and expanding a reinforcing metal and a metal body that causes alkali corrosion through a direct current connected to a negative electrode. Reinforcing the reinforced concrete structure is connected to the positive electrode of the DC power supply unit, and a hole is formed in the reinforced concrete structure, and a metal body that causes alkali corrosion is inserted in the hole with a backfill interposed therebetween. A method for destroying a reinforced concrete structure, comprising: connecting a metal body that generates rust to the negative electrode of the DC power supply device; A metal body that generates alkali corrosion or a metal body that generates alkali corrosion and a backfill is inserted into a hole drilled in a reinforced concrete structure, and the inlet of the hole is sealed with a sealing material. Item 3. A method for destroying a reinforced concrete structure according to item 1 or 2. The metal body that causes alkaline corrosion is any one or more selected from the group consisting of metals of zinc, magnesium, and aluminum, and alloys based on one or more of these metals. Item 4. The method for destroying a reinforced concrete structure according to any one of Items 1 to 3.

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