JP2004257021A - Repair method, repair device and repair monitoring system for concrete structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a repair method for a concrete structure, wherein the repair of the cracked concrete structure and the management of the repair can be easily and surely performed. <P>SOLUTION: In this repair method, the concrete structure 1 is repaired in the following processes: a holder 12 for holding an electrolytic solution 11 is arranged on a surface 1a of the concrete structure 1; an electrode 13, which is installed in the holder 12, is set to be an anode; a reinforcing bar 2 inside the concrete structure 1 is set to be a cathode; and an electric current is applied between the anode and the cathode. A pH of the electrolytic solution 11 is measured, and the application of the electric current is finished when the pH reaches a prescribed value or below. Preferably, the prescribed pH is set in a range of 5.5-6.5. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a concrete structure repair method, a repair apparatus, and a repair monitoring system used for repairing cracks in a concrete structure.
[0002]
[Prior art]
Concrete generally has high durability against the environment such as water, fire and sunlight, and since the concrete is strongly alkaline, the reinforcing steel inside the concrete forms a passive film on its surface and is protected from corrosion. You. For this reason, concrete is widely used for structures constructed outdoors and underground, such as tunnels, retaining walls, and protective walls.
[0003]
If cracks occur in part of the concrete, it will adversely affect the use and maintenance of concrete structures, such as water leakage, corrosion of reinforcing steel, collapse of concrete, etc. It is necessary to perform appropriate repairs.
As a repair method for concrete structures,
(A) a method of injecting an appropriate repair material into a crack and curing the material;
(B) A method in which an anode is installed in seawater, a current is applied between both electrodes using a reinforcing bar in a concrete structure as a cathode, and calcium ions or magnesium ions in the seawater are deposited as electrodeposits at cracks by electrophoresis. ,
Etc. are known.
[0004]
[Patent Document 1]
JP-A-6-65938
[Problems to be solved by the invention]
However, the conventional repair method has the following problems.
In the method (A), it is necessary to reliably inject the repair material into the cracked portion, which requires time and effort for the repair work, and it is difficult to manage the repair work. When insufficient injection or poor curing occurs, it is possible to repair the crack. could not.
The method (B) can be applied to concrete structures constructed facing the sea, such as quays and pier pillars, but can be applied to concrete structures constructed underground or above ground, such as tunnels and retaining walls. Not applicable. In addition, since the repair work was completed by energizing for a predetermined time determined experimentally or empirically, the deposition of electrodeposits was insufficient or excessive depending on the contact of contacts and the scale of cracks during energization. In some cases, cracks could not be completely repaired.
For this reason, there has been a demand for a method capable of reliably repairing cracks in a concrete structure.
[0006]
The present invention has been made in view of the above circumstances, and a concrete structure repair method, a repair apparatus, and a concrete structure capable of easily and reliably performing crack repair of a concrete structure constructed underground or above the ground. It is an object to provide a repair monitoring system.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention arranges a holding body for holding an electrolyte solution on the surface of a concrete structure, uses an electrode provided on the holding body as an anode, and uses a reinforcing bar inside the concrete structure as a cathode to form an anode. A method for repairing a concrete structure by applying a current between the cathode and the cathode to detect a change in the pH of the electrolyte solution, and that the pH value falls below a predetermined value. Thus, a method for repairing a concrete structure, characterized by terminating the application of current, is provided.
According to this repair method, the end of the repair work can be easily and reliably determined based on the change in the pH of the electrolyte solution, and an appropriate amount of electrodeposit can be deposited at the cracked portion.
It is preferable that the predetermined pH value is 5.5 to 6.5. The electrolyte solution is preferably a buffer solution.
[0008]
Further, the present invention provides a holder for holding the electrolyte solution so as to contact the surface of the concrete structure, an electrode installed on the holder, and a reinforcing bar between the reinforcing bar of the concrete structure and the electrode. A repair device for a concrete structure, comprising: a cathode; a DC power supply device for applying a current so that the electrode serves as an anode; and a pH change detecting means for detecting a pH change of the electrolyte solution. .
According to this repair device, the end of the repair work can be easily and reliably determined based on the pH change of the electrolyte solution detected by the pH change detection means, and an appropriate amount of electrodeposit is deposited on the cracked portion. Can be done.
[0009]
Further, the present invention provides a holding member for holding an electrolyte solution so as to contact the surface of a concrete structure, an electrode provided on the holding member, and a reinforcing bar between the reinforcing bar of the concrete structure and the electrode. A DC power supply for applying a current so that the electrode becomes an anode, a pH change detecting means for detecting a pH change of the electrolyte solution held by the holder, and a pH change detected by the pH change detecting means. And a receiving device for receiving the information on the pH change. The repair monitoring system for a concrete structure is provided.
According to this repair monitoring system, information on the pH change of the electrolyte solution can be received at a remote location, and remote monitoring of the repair work becomes possible.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments.
FIG. 1 is a schematic configuration diagram showing a first embodiment of a concrete structure repair apparatus according to the present invention.
In FIG. 1, reference numeral 1 denotes a concrete structure, and the concrete structure 1 is made of concrete 3 in which a reinforcing bar 2 is provided. Reference numeral 4 denotes a crack generated in the concrete structure 1, and the concrete structure repair device 10 (hereinafter, simply referred to as “repair device”) of the present embodiment is a device for repairing the crack 4.
[0011]
The repair device 10 includes a holder 12 that is installed at the cracked portion 4 and holds an electrolyte solution 11, and an electrode 13 provided in the holder 12. The electrode 13 is electrically connected to the reinforcing bar 2 of the concrete structure 1 by an electric wire 14. A DC power supply 15 is provided on the electric wire 14 so that a current can be applied in a direction in which the electrode 13 serves as an anode and the reinforcing bar 2 serves as a cathode. Further, a pH measuring device 16 is provided as a pH change detecting means for detecting a pH change of the electrolyte solution 11 in the holder 12.
[0012]
The holding body 12 is made of a material having high stability to the electrolyte solution 11, and it is necessary that the holding body 12 can hold the electrolyte solution 11 so that it can contact the surface 1 a of the concrete structure 1. A container made of an insulator such as plastic or plastic, or a material capable of adsorbing and holding the electrolyte solution 11 can be used. Examples of the adsorbing material include fibrous materials such as pulp, sponge, glass wool, woven fabric and nonwoven fabric, and porous materials such as zeolite, shirasu, and organic foamed polymers. In addition, the gel can be used as the holding body 12 by adhering a gel formed by mixing a gel such as an organic polymer with the electrolyte solution 11 at a cracked portion.
[0013]
The electrolyte contained in the electrolyte solution 11 needs to contain calcium ions and magnesium ions. Due to the potential difference between the electrode 13 and the reinforcing bar 2, these ions migrate toward the reinforcing bar 2 serving as a cathode, and on the concrete 3, calcium carbonate (CaCO ₃ ) or magnesium hydroxide [Mg (OH) ₂ ] It is deposited as an electrodeposit consisting of The electrodeposits thus deposited fill the gaps of the cracks 4 and a layer of the electrodeposits is formed up to the surface 1a of the concrete structure 1, whereby the cracks 4 are repaired and the surrounding concrete 3 The surface is also reinforced, and the durability of the concrete structure 1 is improved.
[0014]
Further, as described later, in order to provide a buffering action to the electrolyte solution 11, acetic acid, citric acid, anions of organic acids such as other carboxylic acids, phosphate ions, hydrogen phosphate ions, dihydrogen phosphate ions, An anion which is a weak base such as borate ion is added.
The electrolyte added to the electrolyte solution 11 contains the above-mentioned ions, and in particular, magnesium acetate, calcium acetate, and the like are preferable in consideration of solubility in water, safety (toxicity), price, and the like. .
The concentration of the electrolyte added to the electrolyte solution 11 varies depending on the type of the electrolyte, the scale of the crack 4, and the like, and is not particularly limited, but is, for example, 0.1 to 0.5 mol / l. Is preferred.
[0015]
As the electrode 13, a conductor having high corrosion resistance, such as titanium, a titanium alloy, platinum, or carbon, is suitably used. Examples of the shape include a lattice shape, a ribbon shape, a sheet shape, and a comb shape, and the crack 4 is exposed. It is preferable to form a mesh (mesh-like shape) so that the spot can be covered more widely.
The current density of the current supplied by the DC power supply 15 is preferably 1.0 A / m ² or more.
The pH measuring device 16 is not particularly limited, and a commercially available general pH meter can be used.
[0016]
Next, an embodiment of a method for repairing a concrete structure of the present invention using the above-described repair device 10 (hereinafter, simply referred to as “repair method”) will be described. In this repair method, a current is applied between the reinforcing bar 2 and the electrode 13 by the DC power supply device 15. As a result, the following electrode reaction proceeds in the reinforcing bar 2 and the electrode 13 in the electrolyte solution 11.
[0017]
(Rebar 2 side as cathode)
2H ₂ O + 2e ⁻ → 2OH ⁻ + H ₂ (1)
[0018]
(Anode 13 side)
^{_{2H 2 O → O 2 + 4H}} + + 4e - ····· (2)
[0019]
In this way, hydroxide ions are generated in the vicinity of the reinforcing bar 2 serving as the cathode by the electrolysis of water, and as described above, the deposition of electrodeposits such as calcium carbonate and magnesium hydroxide proceeds. On the other hand, on the side of the electrode 13 serving as the anode, hydrogen ions are generated, the pH of the electrolyte solution 11 is reduced, and the electrolyte solution 11 changes to an acidic side.
[0020]
If the pH of the electrolyte solution 11 is excessively changed to an acidic side, the surface 1a of the concrete structure 1 may be dissolved and the concrete structure 1 may be damaged. Thereby, even if the energization is continued, the decrease in the pH of the electrolyte solution 11 can be gradually reduced, and finally, the pH can be stabilized in a weakly acidic range (pH 7 to 5.5).
[0021]
The progress of the repair work is determined based on a change in the pH of the electrolyte solution 11 measured by the pH meter 16. As shown in FIG. 5, this change in pH involves three stages: (a) a stage in which the pH rapidly changes, (b) a stage in which the pH gradually decreases, and (c) a stage in which the pH change becomes small. Contains.
Thus, the repair work is stopped when it is detected that the pH change measured by the pH measuring device 16 has passed through the above three steps and the pH of the electrolyte solution 11 has decreased to a predetermined value.
As a result, it is possible to confirm that the electrode reaction by the repair work has proceeded appropriately, and it is possible to grasp the consumption of the electrolyte solution 11 (the deposition amount of electrodeposits) due to energization. Is realized.
[0022]
FIG. 2 is a schematic configuration diagram showing a concrete repair device according to a second embodiment of the present invention. In the figure, the same reference numerals as those used in FIG. 1 indicate the same or similar configuration as in the first embodiment, and a duplicate description will be omitted.
In the repair device 20 shown in FIG. 2, a pH indicator is used as a pH change detecting means. As the pH indicator, various commercially available indicators exhibiting a clear change in color in a predetermined pH range can be applied.
[0023]
In particular, an indicator A for detecting a transition from step (a) to step (b) corresponding to the three steps (a), (b), and (c) described above, It is preferable to use together with the indicator B for detecting the transition to the step (c).
For example, as indicator A, phenol red (PR) having a discoloration range of "yellow 6.4 to 8.4 red" is used, and as indicator B, the discoloration range is "yellow 6.0 to 7.0 blue". Bromthymol blue (BTB) can be employed.
[0024]
Here, as shown in FIG. 2, the indicator A and the indicator B are separately supported on the carriers 21 a and 21 b such as paper and gel so as not to be mixed with each other, and the carriers 21 a and 21 b are contained in the electrolyte solution 11. Is immersed in.
The fact that the pH value has decreased due to the progress of the repair work and the transition from step (a) to step (b) can be detected by a change in the coloration of the indicator A. Further, the progress of the repair work and the transition from the step (b) to the step (c) can be detected by a change in the coloration of the indicator B, and in view of this, the repair work is stopped.
As a result, it is possible to confirm that the electrode reaction by the repair work has proceeded appropriately, and it is possible to grasp the consumption amount of the electrolyte solution 11 (the deposition amount of the electrodeposit) due to energization. And the concrete structure 1 can be reliably repaired.
[0025]
FIG. 3 is a schematic configuration diagram illustrating a first embodiment of a concrete repair monitoring system according to the present invention. In the drawing, the same reference numerals as those used in FIG. 1 indicate that the configuration is the same as or similar to that of the above-described embodiment, and redundant description will be omitted.
The repair monitoring system 30 shown in FIG. 3 receives the repair device 10 described above, a transmitting device 31 connected to the pH measuring device 16 of the repair device 10, and data transmitted from the transmitting device 31 through the communication network 32. A receiving device 33, a computer 34 for analyzing data received from the receiving device 33, and a display device 35 for displaying an analysis result.
Specific examples of the communication network 32 include a general telephone network, the Internet, a dedicated cable line, general wireless communication and satellite communication. As the transmission device 31 and the reception device 33, those suitable for the communication network 32 are appropriately used, and as the computer 34 and the display device 35, commercially available appropriate devices can be adopted.
[0026]
Next, a repair method using the repair monitoring system 30 will be described. Here, as described in the first embodiment of the repair device described above, an electric current is applied between the reinforcing bar 2 and the anode 13 to deposit electrodeposits on the cracks 4. At this time, the pH of the electrolyte solution 11 is measured by the pH meter 16 and the obtained measured value is transmitted to the computer 34 through the communication network 32 periodically, irregularly, or in real time. The computer 34 analyzes the pH change based on the received data according to an analysis program prepared in advance. It is determined whether or not the change in pH has passed the above-described three steps (a) to (c), and whether or not the pH of the electrolyte solution 11 has decreased to a predetermined value. The analysis result is appropriately displayed by the display device 35. As a result of the analysis, when the end point of the repair work is recognized, a display indicating the end of the repair work is displayed on the display device 35. The observer periodically monitors the display on the display device 35, and when recognizing the end of the repair work, dispatches the worker to the repair site to complete the repair work.
In this case, since the electrolyte solution 11 is a buffer solution, the pH of the electrolyte solution 11 is stabilized at the end of the repair work so that a sudden pH change does not occur. There is no danger.
In the repair monitoring system of the present embodiment, by giving an appropriate program to the computer 34, it is possible to predict how many days the repair work will be completed based on the received data. In this case, work schedule management can be facilitated.
[0027]
According to such a repair monitoring system, the repair work of the concrete structure can be remotely monitored. Further, since it is not necessary for the worker to go to the repair site to check and investigate the progress of the repair work, labor can be greatly reduced. No special equipment is required for the construction of the repair monitoring system, and it can be performed at a relatively low cost.
[0028]
FIG. 4 is a schematic configuration diagram illustrating a concrete repair monitoring system according to a second embodiment of the present invention. In the drawings, the same reference numerals as those used in FIGS. 1 to 3 indicate that they have the same or similar configurations as those of the above-described embodiment, and redundant description will be omitted.
The repair monitoring system 40 includes the repair device 20 according to the above-described second embodiment, a camera 41 that captures a color change of the pH indicator carried on the carriers 21a and 21b of the repair device 20, and a captured image. A transmitting device 31 for transmitting image data through the communication network 32, a receiving device 33 for receiving data from the communication network 32, a computer 34 for analyzing the data received from the receiving device 33, and a display device 35 for displaying the analysis result; It has.
[0029]
In the repair method using the repair monitoring system 40, first, data indicating a pH change obtained by the camera 41 is obtained. Then, similarly to the repair monitoring system 30 of the first embodiment, this data is transmitted by the transmission device 31 to a computer 34 located at a remote place through a communication network 32, and the computer 34 analyzes the data. Thereby, the repair work of the concrete structure can be remotely monitored. Further, since it is not necessary for the worker to check and investigate the progress of the repair processing at the repair site, labor can be greatly reduced. No special device is required for the construction of the system, and it can be performed at low cost.
[0030]
As described above, the present invention has been described based on the preferred embodiments, but the present invention is not limited to only the embodiments, and various modifications can be made without departing from the gist of the present invention.
For example, in FIGS. 3 and 4, a communication device (transmitter / receiver) capable of bidirectional transmission and reception is used instead of the transmission device 31 and the reception device 33, and the communication device 31 and the DC power supply device 15 on the repair site side are connected. By connecting with a signal line (not shown), a control signal for controlling on / off of the current of the DC power supply 15 and the amount of the current can be transmitted from the computer 34 to the DC power supply 15 via the communication network 32. You can also In this case, the start and end of the repair work can be remotely controlled.
[0031]
【Example】
A container 12 having a titanium mesh electrode 13 (area: 600 cm ² ) was attached to the cracked portion 4 of the concrete structure 1 using the repair device 10 shown in FIG. An aqueous solution of magnesium acetate was charged. The rebar 2 and the electrode 13 are connected by the electric wire 14, and while the pH of the electrolyte solution 11 is measured by the pH measuring device 16, a current having a current density of 1.0 A / m ² is applied between both electrodes by the DC power supply 15. , And repaired. When the repair was performed under these conditions, a graph shown in FIG. 5 was obtained as a change in pH with respect to the energization time.
After energizing for 14 days, confirming that the decrease in pH became small, the energization was stopped, and the repaired part was visually inspected. Crack 4 and its surroundings were completely covered with electrodeposits, It had a smooth surface. Also, the amount of water leakage from the repair location was measured, but no water leakage was confirmed.
[0032]
【The invention's effect】
As described above, the method for repairing a concrete structure of the present invention detects a change in the pH value of the electrolyte solution, and terminates the application of the current when the pH value falls below a predetermined value. Therefore, the deposition of electrodeposits can be grasped and detected.
As a result, it is possible to confirm that the electrode reaction by the repair work has proceeded appropriately, and it is possible to grasp the amount of consumption of the electrolyte solution and the amount of deposition of electrodeposits due to energization.
[0033]
The repair device for a concrete structure according to the present invention includes the holder for holding the electrolyte solution so as to be in contact with the surface of the concrete structure, so that the electrolyte solution can be easily installed at the cracked portion. In addition, since a pH change detecting means for detecting a pH change of the electrolyte solution is provided, it is possible to reliably know the end point of the repair work.
[0034]
The repair monitoring system for a concrete structure according to the present invention includes the holder for holding the electrolyte solution so as to be in contact with the surface of the concrete structure, so that the electrolyte solution can be easily installed at a crack. Further, since the apparatus includes a pH change detecting means, and a transmitting device and a receiving device for transmitting information on the pH change detected by the pH change detecting means via a communication network, the state of the repair work can be monitored from a remote place. Thus, it is possible to know the end point of the repair work, which greatly contributes to the management of the repair work.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a first embodiment of a concrete structure repair apparatus according to the present invention.
FIG. 2 is a schematic configuration diagram showing a concrete structure repair apparatus according to a second embodiment of the present invention.
FIG. 3 is a schematic configuration diagram showing a first embodiment of a concrete structure repair monitoring system according to the present invention.
FIG. 4 is a schematic configuration diagram showing a second embodiment of the concrete structure repair monitoring system according to the present invention.
FIG. 5 is a graph showing an example of a measurement result of a change in pH of an electrolyte solution in an example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Concrete structure, 1a ... Concrete structure surface, 2 ... Rebar (cathode), 10 ... Repair device, 11 ... Electrolyte solution, 12 ... Holder (container), 13 ... Electrode (anode), 15 ... DC power supply Apparatus, 16 ... pH change detecting means (pH measuring device), 20 ... Repair device, 21a, 21b ... pH change detecting means (carrier of pH indicator), 30 ... Repair monitoring system, 31 ... Transmission device, 32 ... Communication network, 33: receiving device, 40: repair monitoring system.

Claims (5)

A holder for holding the electrolyte solution is placed on the surface of the concrete structure, and the electrode installed on the holder is used as an anode, and a reinforcing bar inside the concrete structure is used as a cathode, and a current is applied between the anode and the cathode. A method for repairing a concrete structure, the method for repairing a concrete structure,
A method for repairing a concrete structure, comprising detecting a change in the pH of an electrolyte solution and terminating the application of an electric current when the pH value falls below a predetermined value. The method for repairing a concrete structure according to claim 1, wherein the predetermined pH value is 5.5 to 6.5. 3. The method for repairing a concrete structure according to claim 1, wherein the electrolyte solution is a buffer solution. A holder for holding the electrolyte solution so as to be in contact with the surface of the concrete structure, an electrode installed on the holder, and between the reinforcing bar of the concrete structure and the electrode, the reinforcing bar is a cathode, and the electrode is an anode. An apparatus for repairing a concrete structure, comprising: a DC power supply for applying a current so as to satisfy the following condition; and a pH change detecting means for detecting a pH change of the electrolyte solution. A holder for holding the electrolyte solution so as to be in contact with the surface of the concrete structure, an electrode installed on the holder, and between the reinforcing bar of the concrete structure and the electrode, the reinforcing bar is a cathode, and the electrode is an anode. A DC power supply for applying a current so as to satisfy the following conditions; pH change detecting means for detecting a pH change of the electrolyte solution held in the holder; A repair monitoring system for a concrete structure, comprising: a transmitting device that transmits the information via a PC; and a receiving device that receives the information on the pH change.

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