JP5422791B2 - Method for repairing concrete structure and structure for preventing rebar corrosion of concrete structure - Google Patents

Description

  The present invention relates to a repair method for a concrete structure and a reinforcing bar corrosion prevention structure for a concrete structure.

JP 2003-120041 A

As a repair method for reinforced concrete structures that have deteriorated due to salt damage, after the concrete in the deteriorated part is removed, the repaired concrete or mortar is applied to the surface of the removed concrete cross section. Is generally done.
On the other hand, at the boundary between the rebar inside the repaired concrete and the rebar inside the sound concrete, the natural potential, which is a parameter indicating the corrosion tendency of the rebar, changes extremely, and a relatively large cell (electrical) Circuit) is formed, and corrosion called macrocell corrosion proceeds.

  Specifically, in a reinforced concrete structure that has deteriorated due to salt damage, neutralization, frost damage, etc., when the section of concrete that has deteriorated in the section that newly includes the reinforcing bar is removed and replaced with new concrete, The macrocell corrosion circuit is formed through the reinforcing bars due to the difference in salinity between the concrete, and the progress of the reinforcing bar corrosion near the repaired part is accelerated.

As a method for preventing such macro cell corrosion,
(1) Cathodic protection methods such as galvanic anode method and external power supply method
(2) Electrochemical desalination method
(3) Methods such as lithium nitrite admixed polymer cement mortar spraying have been adopted.
Among these, the cathodic protection method (1) requires large-scale equipment, and it has a large burden in terms of cost and equipment maintenance, and there are many problems. The electrochemical desalination method (2) also requires large-scale equipment. The construction method (3) is not only problematic in terms of cost, especially in concrete structures where sea sand is used during construction and the salt concentration is high, and nitrite is usually carcinogenic. There is a risk that its use will be limited in the near future.

For example, in the above-mentioned Patent Document 1, after the concrete at the repaired portion of the concrete structure is removed, an aqueous nitrite solution is applied to the adhesive interface between the removed portion and the cross-sectional repair mortar and the entire exposed reinforcing bar surface. Then, after a polymer cement mortar is applied, a repair method for salt damage deteriorated concrete has been proposed, characterized in that the cross section is repaired using the cross section repair mortar.
According to this method, the natural potential of the reinforcing bar can be gradually changed from the joint interface to the healthy concrete at the boundary between the repaired reinforcing steel inside the reinforcing steel and the healthy concrete inside reinforcing bar. It is possible to prevent macrocell corrosion by preventing the potential from changing drastically. In addition, a barrier layer against chloride ion permeation is formed at the adhesion interface between the removed portion and the repaired mortar, and the suspended portion. Even when there are high concentrations of chloride ions penetrating deeper, these high concentration chloride ions are prevented from returning to the vicinity of the rebar due to the action of the concentration gradient and causing corrosion of the rebar. It is said that it is possible to prevent deterioration and generation of rust over a long period of time.

However, the repair method disclosed in Patent Document 1 is a method in which nitrite is acted as a sacrificial anode by reacting nitrite ions with salt in concrete to prevent corrosion of reinforcing steel, and has a high salinity concentration and contains salinity. If the amount is large, a large amount of nitrite is required.
Therefore, if the nitrite reacts to become a salt for a long time, the intrusion of chloride cannot be suppressed.
In addition, as described above, the problem of carcinogenicity of nitrite cannot be avoided by the method disclosed in Patent Document 1.

From such a background, as a method of repairing a concrete structure damaged by salt damage, a method for preventing macrocell corrosion over a long period of time, in which measures for macrocells in the cross-section repaired part have been taken, has been eagerly desired. Safe, economical, and easy on-site construction is desired.
This invention provides the repair method of such a concrete structure, and aims at solution of said subject.

The first invention of the present application newly applies uncured concrete to a part of the concrete structure from which the concrete is removed after removing the concrete in the repaired part of the concrete structure including the steel material which is a reinforcing bar or a steel pipe. In the repair method of the concrete structure which is to be performed, the following structure is provided.
That is, the removal of the concrete in the repaired part is to expose the rusted part of the steel material by removing the concrete in a state where the entire outer periphery of the steel material is exposed in a part of the steel material in the longitudinal direction. After removing the concrete of the restoration part, apply an insulating agent to the entire surface of the concrete structure where the concrete has been removed, and newly apply uncured concrete. The insulating agent is infiltrated from the concrete surface of the part from which the repaired part is removed, and the infiltration layer of the insulating agent is formed from the entire concrete surface of the part from which the concrete has been removed to the inside of the concrete of the part. And applying the uncured concrete to the portion of the concrete to which the insulating agent is applied, By covering the portion where Tsu is intended to impart new concrete throughout the periphery, a portion contacting with the boundary between the concrete has not been removed and newly granted concrete at the surface of the steel material, and the permeation layer It is characterized by being in contact.
In addition, the concrete here includes mortar.

  In the second invention of the present application, in the first invention of the present application, the insulating agent contains an alkylalkoxysilane-based material or a silanesiloxane-based material, and is a liquid having a viscosity smaller than 10 mPas. And providing a method for repairing a concrete structure, characterized in that the uncured concrete is intruded into the unevenness of the concrete surface coated with an insulating agent.

  In the third invention of the present application, in the second invention of the present application, the insulating agent is an alkylalkoxysilane-based material, and the insulating agent is insulated by applying the insulating agent to the concrete removal portion of the concrete structure a plurality of times. After forming the osmotic layer of the agent, the uncured concrete is newly replenished, and during the plurality of times of application, the next application is performed with at least the appearance of the concrete surface being dry. A method for repairing a concrete structure is provided.

In the fourth invention of the present application, for a concrete structure provided with a steel material that is a reinforcing bar or a steel pipe, the concrete in the restoration part is removed, and the concrete is newly added to the part from which the concrete is removed. A rebar corrosion prevention structure for a concrete structure having the following configuration is provided.
That is, an infiltrated layer in which an insulating agent penetrates from the entire interface between the old concrete part from which the concrete of the concrete structure has not been removed and the newly formed new concrete part to the inside of the old concrete part is provided. And the new concrete part are electrically insulated, and part of the steel material is inside the new concrete part in the longitudinal direction of the steel material, and the entire outer periphery of the steel material in the part is inside the new concrete. The part of the surface of the steel material in contact with the interface is in contact with the permeation layer .

Each invention of the present application increases the electric resistance between old and new concrete by applying an insulating agent to the surface of the concrete structure where the concrete has been removed before newly applying uncured concrete. The formation of (electric circuit) was made difficult.
Thus, macro cell corrosion can be prevented over a long period of time by repairing the reinforced concrete structure.
In addition, it is not necessary to replenish a large amount of nitrite as in the construction method shown in Patent Document 1 using a nitrite aqueous solution, and safety is also improved because nitrite is not used from the beginning. Furthermore, it was possible to provide a construction method that was excellent in economic efficiency and easy on-site construction.
In particular, in the second invention of the present application, by employing an insulating agent containing a silane-based insulator or a siloxane-based insulator, it is possible to provide specific means that does not impair the fixing property between concrete as well as insulation. It was. In the third invention of the present application, a preferable construction method of such an insulating agent is provided.

A preferred embodiment of the present invention will be described with reference to the drawings.
1 to 3 show an embodiment of the present invention. Each of FIGS. 1-3 is explanatory drawing of each process of the repair method of the concrete structure based on this invention.
The repair method of the concrete structure provided with the reinforcing bar which concerns on this invention performs a concrete removal process, an insulating layer formation process, a concrete replenishment process, and a curing process in order.
Hereinafter, each process is demonstrated in order.

In the concrete removing step, a concrete structure deteriorated due to salt damage shown in FIG. 1 (A) or a concrete structure predicted to be deteriorated is called a portion to be repaired (hereinafter referred to as a repair portion 2). .)) Using a known device such as an excavator, as shown in FIG. 1 (B).
The range to be picked up is determined according to the degree of deterioration of the concrete. Specifically, for rusted portions of steel materials such as reinforcing bars and steel pipes, the concrete around the steel materials is scraped. Also, if there are cracks or defects in the concrete, remove the surrounding area.
Adopting well-known fluoroscopic means such as ultrasonic waves and X-rays, and well-known deterioration of structures, even if it is impossible to confirm deterioration from the outside by visual inspection Visual inspection by applying a diagnostic agent (coloring agent), collecting a sample from a concrete structure, or grasping the internal situation from the design drawing of the structure and considering the elapsed time since construction. The range to be picked up may be determined by a method other than the above and picked up.
When the deteriorated part reaches the reinforcing bar 3, the concrete is suspended until the reinforcing bar 3 is exposed. However, from the degree of deterioration and the ease of construction, it is assumed that the rebar 3 is not exposed to the extent that the rebar 3 is not exposed, and the implementation is not limited.

As shown in FIG. 2A, after the concrete of the repaired portion 2 is picked up by the concrete removing step, an insulating layer is formed on the concrete structure 1 by the insulating layer forming step. The insulating layer is formed by applying an insulating agent z to the concrete surface (hereinafter referred to as the exposed surface 11) exposed by suspending.
As the insulating agent z, a material that electrically insulates the concrete and does not hinder the adhesion between the concrete is employed. As such an insulating agent z, it is preferable to employ a water repellent containing a silane-based insulator or a siloxane-based insulator.
As such an insulating agent z, an alkylalkoxysilane, an alkylalkoxysiloxane, an isobutyltriethoxysilane, an octyltriethoxysilane, a low-viscosity propylethoxysiloxane, a material containing two or more of these, or a condensate thereof is used. can do. Also optionally mixed with a compound having an amino group, such as aminosilane, aminopropyltriethoxysilane, or amino alcohol miscible with the silane system used, diethylaminoethanol, or a long chain carboxylic acid or the carboxylic acid Admixed with calcium salt or magnesium salt, calcium dinonylnaphthalene sulfonate and optionally added or added with other components (eg water, solvent or processing aid), adopted as insulating agent z can do. Furthermore, those containing an organosilane or organosiloxane or other components can be employed by mixing these components well or stirring together.

Preparation and application in the case of employing an alkylalkoxysilane as the insulating agent z will be described. The alkylalkoxysilane and the corresponding siloxane are optionally mixed with an amino-functional compound and a carboxylic acid or carboxylic acid salt. The resulting mixture is single phase. Optionally, supplementary stirring and heating. Mixing times from 20 ° C. up to 1 minute to several hours in the temperature range where the alkylalkoxysilane mixture or alkylalkoxysiloxane mixture begins to boil (up to about 180 ° C.) are advantageous. At that time, a chemical reaction may proceed. The following can be mentioned as an example here.

R-Si (OR ¹ ) ₃ + n (C ₂ H ₅ ) NC ₂ H ₄ OH
→ R-Si (OR ¹ ) _3-n [(C ₂ H ₅ ) NC ₂ H ₄ O] _n
+ NR ¹ OHR-Si (OR ¹ ) ₃ + nR ² COOH
→ R-Si (OR ¹ ) _3-n (R ² COO) _n R ¹ OH
The resulting single-phase mixture is usually liquid and has a low viscosity (viscosity is usually less than 10 mPas, generally less than 5 mPas, especially in the smallest case less than 1.5 mPas). A solvent can additionally be used to adjust the viscosity. Suitable solvents are, for example, alcohols, preferably ethanol, methanol or isopropanol or benzine hydrocarbons, such as petroleum benzine or solvent oil. The liquid insulating agent z is applied directly on the concrete surface, or is prepared as an oil-in-water emulsion by a known method, and is applied on the concrete surface in the form of an aqueous emulsion. In the case of aqueous emulsions, high viscosity emulsions can also be applied in addition to low viscosity emulsions. In this case, what is important is that a sufficient amount of active substance (not solvent, emulsion = water, not continuous phase) penetrates into the concrete. In order to achieve this, it is preferable to apply the insulating agent z to the concrete surface several times. However, if necessary, one-time application is also possible. When applying multiple times, the surface must be at least dry before starting the next application. Protectsil CIT (trade name) can be employed as the alkylalkoxysilane.
On the other hand, for application of the silane siloxane material, for example, when a magical repeller (trade name) is used, it is preferably applied in an amount of 50 to 500 g / m ² .
When employing an alkylalkoxysilane, it is particularly preferable to employ one containing 95.0 to 99.0% by weight of triethoxyisobutylsilane.
Moreover, about the silane siloxane type material, it is preferable to employ | adopt the thing of the following mixing | blending, for example.
Organosilane and silicone 75-85% by weight
Water, other 25-15% by weight
Total 100%

About spraying (application | coating) of said insulating agent z, it can carry out by spraying the insulating agent z on the whole exposed surface 11 uniformly.
Spraying can be performed using a well-known spraying means s such as a spray gun or a spray gun equipped with a compressor. In addition to spraying, the present invention can be applied to the exposed surface 11 by brush or roller.
The formation of the insulating layer by the above-described insulating agent z will be described more specifically.
As shown in FIG. 2 (B), the insulating agent z penetrates from the exposed surface 11 into the remaining concrete (referred to as the old concrete portion 4) without being scraped off by the above spraying. Layer 5 is formed. The penetration layer 5 is preferably formed as a layer having a depth of 0.1 to 3 cm from the exposed surface 11. In particular, the depth of the permeation layer 5 is preferably 1 cm.
The osmotic layer 5 can be formed by one application (spraying), but as described above, it can be formed by a plurality of applications (spraying).
As said alkyl alkoxysilane used for the insulating agent z, what makes the whole 100% and contains the triethoxyisobutylsilane 20weight% or more and 2-diethylaminoethanol 5weight% or less is employable.
When the above-mentioned protectsil CIT (trade name) is employed as such an alkylalkoxysilane, coating twice is preferable. That is, undercoating is performed with protect sill CIT, and after drying, overcoating is performed with protect sill CIT.
However, when protectsil CIT or other alkylalkoxysilane is employed as the insulating agent z, the permeation layer 5 may be formed by a single application.
Although illustration is omitted, by applying the above alkylalkoxysilane twice as the insulating agent z, a layer having a high density of the insulating agent z is usually formed from the exposed surface 11 to a shallow portion. A layer having a slightly lower density of the insulating agent z is formed adjacent to the high insulating layer 5 on the opposite side (deep part) from the exposed surface 11.
Further, when the above-described magic repeller is employed as the silane siloxane-based material as the insulating agent z, the permeation layer 5 can be formed by a single application. However, even in this case, it is possible to carry out the application twice.
In particular, when a magic repeller is used as the insulating agent z, it is preferable to coat with a commercially available sealer, such as “Magical Color” (trade name), after coating and drying. By applying such a sealer, the adhesion of old and new concrete can be enhanced. However, when a magical repeller is employed, it can be carried out without applying a sealer.

After the insulating layer forming step, as shown in FIG. 3A, in the concrete replenishing step, the uncured concrete is applied on the insulating layer to form the repaired portion 7. That is, as shown to FIG. 3 (B), a new concrete part is formed as the repair part 7, and the location where the old concrete part 4 was suspended is covered.
In addition, as shown in FIG. 3 (B), the repair portion 7 with new concrete replenishes the concrete that has been removed and is applied to a thickness that is greater than that before the removal, in addition to being restored to the same state as before the removal. It is also possible to apply thinly or to change.
After application of the new concrete, that is, after the repair portion 7 is formed, the new concrete (the repair portion 7) is cured in a curing process. The curing process is a process in which the applied new concrete (repair part 7) is completely cured over time, and the time to be left may be adjusted depending on the components and the application amount of the new concrete.
Moreover, what is necessary is just to cover the site | part which applied the new concrete with sheets, such as a blue sheet, during a curing period as needed.

Microscopically, the penetration layer 5 (insulating layer) formed at the site where the repair has been completed as described above does not completely insulate the electric current between the old and new concrete. That is, the insulating agent z is not interposed as an insulating film between the old and new concrete (it does not form a film on the old and new concrete interface).
The penetration layer 5 of the insulating agent z will be described in detail. The concrete surface is rough, and there are capillary irregularities from the surface to the inside, and the insulating agent z sprayed between the irregularities of the capillary tube penetrates. By doing so, the osmotic layer 5 is formed. However, the insulating agent z does not inhibit the intrusion of the new concrete into the unevenness of the old concrete. Accordingly, the concrete is continuous except for the portion where the insulating agent enters, and is not interrupted by the insulating agent z. For this reason, as described above, it can be said that the old and new concrete is not completely electrically insulated from the microscopic viewpoint.
However, macroscopically, the formation of the permeation layer 5 increases the electrical resistance value (compared to the case where the permeation layer 5 is not formed) in the entire space between the old and new concrete, thereby suppressing current conduction between the old and new concrete. It can be done.
For example, if the insulating agent z is present as an insulating coating at the interface between the old and new concrete, the old and new concrete cannot be in direct contact, and the bonding force of the concrete itself does not function at all. However, by forming the above-mentioned permeation layer 5 as an insulating layer, the contact between the old and new concrete is not hindered by the insulating agent z. There is no such thing as not doing.
Further, since the protect sill CIT and the magical repeller also have a water repellent effect, the infiltration of water serving as an electric conductor is suppressed, and also in this aspect, it indirectly helps to suppress energization.

In order to confirm the effect of the increase in electrical resistance due to the application of silane-based insulating material between the base material and the repair material on the macrocell corrosion on the reinforcing bar, a reinforcing bar corrosion test was conducted.
As this rebar corrosion test, an indoor test and an on-site construction test were conducted.

First, the laboratory test will be described.
FIG. 4 shows a test specimen of the example. The base material a (equivalent to the old concrete part 4) side is mixed with salt at a rate of 10 kg per cubic meter, while the restoration material b side (equivalent to the added part / new concrete or repair part 7) is salted. It was not mixed. Moreover, the insulating agent was apply | coated to the base material a side joint surface before the addition. The above-mentioned salt content was mixed into the base material a by kneading into the base material a before curing.
Specifically, the test specimen was not coated with an insulating agent (reference case) (No. 1), the insulating material was a silane-based reinforced corrosion inhibitor (No. 2), and the insulating agent. (No. 3) was prepared by using a silanesiloxane-based permeable water absorption inhibitor.
Specifically, “Protect Sil CIT” (trade name) is used as a silane-based permeable reinforcing bar corrosion inhibitor (No. 2), and “Magical Repeller” is used as a silane siloxane-based permeable water absorption inhibitor (No. 3). Product name). Regarding the coating amount of the insulating agent, no. 2 is 600 ml / m ² . 3 was 200 g / m ² .
In addition, said No .. For No. 3, an insulating agent having a blending of 80% by weight of a magical repeller and 20% by weight of water (100% in total) was employed. Further, a magical color (trade name) 100 g / m ^{2 was} applied as a sealer.

The materials used for the test specimen are as follows.
Water (W): Tap water Cement (C ₁ ): Normal Portland cement
Density 3.16 g / cm ³ , specific surface area 3290 cm ² / g
Cement (C _2): early strength Portland cement
Density 3.14 g / cm ³ , specific surface area 4500 cm ² / g
Fine aggregate (S): surface dry density 2.59 g / cm ³ , coarse grain ratio 2.58
Coarse aggregate (G): surface dry density 2.69 g / cm ³ , maximum particle size 20 mm
Water reducing agent (Ad ₁ ): Floric S (trade name)
AE agent (Ad ₂ ): Floric AE-6 (trade name)

About the mixing | blending of the said use material of base material concrete (old concrete), and the hardness of the concrete before hardening by the result of a slump test (Slump), it is as follows.
Water (W): 180 kg / m ³
Cement (C1): 360 kg / m ³
Fine aggregate (S): 782 kg / m ³
Coarse aggregate (G): 970 kg / m ³
Air (Air): 2% (volume%)
Slump: 3.5cm

About the mixing | blending of the said use material of an extension concrete (new concrete) and the hardness of the concrete before hardening by the result of a slump test (Slump), it is as follows.
Water (W): 200 kg / m ³
Cement (C2): 370 kg / m ³
Fine aggregate (S): 848 kg / m ³
Coarse aggregate (G): 886 kg / m ³
Water reducing agent (Ad1): 111 kg / m ³
AE agent (Ad2): 0.074 kg / m ³
Air (Air): 3% (volume%)
Slump: 6.5cm

  In the test body, split rebars 3 ... 3 were embedded in the center of the test body in order to distinguish and measure the macrocell corrosion current and the microcell corrosion current. As shown in FIG. 4, the test body was a cylindrical body having a diameter r of 5 cm, in which a restoration material b was extended to a base material a. Rebars 3 and 3 each having a length t1 of 3 cm were embedded in the center of the base material a. Further, a reinforcing bar 3 having a length t2 of 6 cm was embedded in the center of the restoration material b. The reinforcing bars 3 and 3 are electrically connected by lead wires 8 and 8.

There are three measurement items: macrocell corrosion current, microcell corrosion current, and electrical resistance between the base material and the repair agent.
Here, the macrocell corrosion current is a current flowing between the reinforcing bars 3, 3, and 3 and was measured by a non-resistance ammeter. On the other hand, the microcell corrosion current is a current flowing in the reinforcing bar, and was calculated by an AC impedance method using a frequency response analyzer (FRA).
Moreover, the electrical resistance between the base material a and the repair material b (addition part) was measured by the alternating current impedance method using FRA between the reinforcing bar elements at the ends. Macrocell corrosion current and electrical resistance were measured at 1st, 2nd, 3rd and 4th weeks of age, and microcell corrosion current was measured at 1st and 4th weeks.

  After placement, all specimens were cured and exposed in a humid atmosphere (RH 90%). In order to suppress initial surface cracks, the temperature was set to 20 ° C. until the age of one week, while the temperature was set to 50 ° C. after one week to promote corrosion.

The measurement result of the macrocell corrosion current at the age of 4 weeks is shown in the graph of FIG. In the graph of FIG. 1 shows the measurement results of the test specimen No. 1, and the white square is the above No. 1. No. 2 specimen, the black triangle is the above No. 2. 3 specimens are shown.
From the graph of FIG. 5, in the uncoated specimen (No. 1), it is confirmed that the macrocell corrosion current density varies greatly depending on the position of the rebar embedded, and the macrocell corrosion progresses on the base material a side. it can. On the other hand, in the test body (No. 2) using the silane-based permeable reinforcing bar corrosion inhibitor and the test body (No. 3) using the silane siloxane-based permeable water absorption inhibitor, the macrocell corrosion current depending on the position of the reinforcing bar. A change in density is small, and it can be confirmed that the macrocell corrosion is suppressed as compared with the uncoated specimen (No. 1).

FIG. 6 shows the change with time of the maximum value of the macrocell corrosion current density up to the fourth week of the material age. From FIG. 6, the maximum value of the macrocell corrosion current density of the test body (No. 2) using the silane coating agent and the test body (No. 3) using the silane siloxane coating agent is compared with that of no coating. It can be confirmed that it occupies a low value. Although not shown, the same tendency was observed with respect to the microcell corrosion current density.
The measurement result of the electrical resistance at the age of 4 weeks is shown in FIG. From FIG. 7, the electrical resistance values of the test body (No. 2) using the silane-based coating agent and the test body (No. 3) using the silane siloxane-based coating agent are the uncoated test body (No. 1). It can be confirmed that the value is higher than Therefore, by applying a silane-based or silanesiloxane-based coating agent to the base material a side joining surface (equivalent to the exposed surface 11), the electrical resistance between the base material a and the repair material b is increased, and macrocell corrosion is suppressed. Is clear.

Next, an on-site construction test will be described.
Based on the above-mentioned laboratory test results, in a reinforced concrete bridge having an internal salt content, an attempt was made to suppress macrocell corrosion occurring in a cross-sectional repaired part by using a silane-based coating material and a silanesiloxane-based coating material.
Here, in order to monitor the macro cell corrosion rate, as shown in FIG. 8, mini sensors s1 and s2 were embedded in the vicinity of the reinforcing bar 3 in the old and new concrete (base material a and restoration material b).
The mini sensors s1 and s2 are sensors that can detect a potential. In FIG. 8, reference numeral 12 denotes an insulating layer.

Using the minisensors s1 and s2, the natural potential, the polarization resistance, and the concrete specific resistance were measured periodically to calculate the macro cell corrosion rate.
A graph of the macrocell corrosion rate in the second month after the construction is shown in FIG.
In FIG. 9, A and F show the measurement results at the span end, and B to E show the measurement results at the center of the span.
Among these, a silane-based reinforced reinforcing bar corrosion inhibitor was used as an insulating agent for A to C, and a silane siloxane-based permeable water absorption inhibitor was used for D to F.
From the graph of FIG. 9, it can be confirmed that the macro cell corrosion rate at any point of A to F shows an extremely low value of 0.0010 mm or less per year.

  Summarizing the above test results, by applying a silane-based reinforced corrosion inhibitor and silanesiloxane-based water absorption inhibitor to the joint surface, the electrical resistance between the base material and the repair material is increased, and the macrocell corrosion Since the formation of the circuit is suppressed, an anticorrosive effect can be expected. Therefore, it is considered to be an effective method as a countermeasure for macrocell corrosion of the joint portion under the condition of thickening and reinforcing the base material concrete containing a large amount of internal salt. In the future, it will be important to continuously measure the corrosion rate and electrical resistance and use them for maintenance in order to grasp the effects of aging suppression in actual bridges.

(A) is a partially cutaway schematic cross-sectional view of a concrete structure that is a target of the repair method according to the present invention, and (B) is a part of the concrete structure showing the concrete removal step of the repair method according to the present invention. It is a notch schematic sectional drawing. (A) is a partially cutaway schematic cross-sectional view of a concrete structure showing the start of an insulating layer forming step of the repair method according to the present invention, and (B) is a concrete showing a permeation layer formed in the insulating layer forming step. It is a partially cutaway schematic cross-sectional view of a structure. (A) is a partially cutaway schematic cross-sectional view of a concrete structure showing a performance state of a concrete replenishment process, (B) is a partially cutaway schematic cross-sectional view of a concrete structure showing a state where the concrete replenishment process is completed. is there. It is explanatory drawing of the test body of a laboratory test. It is explanatory drawing which shows the graph of the macrocell corrosion current density of a laboratory test. It is explanatory drawing which shows the graph of the maximum value of the macrocell corrosion current density of a laboratory test. It is explanatory drawing which shows the graph of the electrical resistance of a room test. It is explanatory drawing of a site construction test. It is explanatory drawing which shows the graph of the macrocell corrosion rate of an on-site construction test.

DESCRIPTION OF SYMBOLS 1 Concrete structure 2 Repair part 3 Reinforcement 4 Old concrete 5 Penetration layer 7 New concrete 10 Surface 11 (of concrete structure) Exposed surface s Spray gun z Insulating agent

Claims (4)

For concrete structures equipped with steel materials such as reinforcing bars or steel pipes, after removing the concrete in the restoration part, the concrete structure that newly gives uncured concrete to the part of the concrete structure from which the concrete has been removed In the repair method of
The removal of the concrete in the repaired part is to expose the rusted part of the steel material by removing the concrete in a state where the entire outer periphery of the steel material is exposed in a part of the steel material in the longitudinal direction. And
After removing the concrete of the restoration part, an insulating agent is applied to the entire surface of the concrete structure where the concrete is removed, and uncured concrete is newly added.
By the application, the insulating agent penetrates from the concrete surface of the part from which the repaired part is removed, and the permeation layer of the insulating agent is applied from the entire concrete surface of the part from which the concrete is removed to the inside of the concrete of the part. To form,
By applying the uncured concrete to the portion of the concrete to which the insulating agent has been applied and covering the suspended portion, new concrete is applied to the entire outer periphery, and is newly applied to the surface of the steel material. A method for repairing concrete, wherein a portion in contact with a boundary between the applied concrete and the concrete that has not been removed is in contact with the permeation layer.
The insulating agent contains an alkylalkoxysilane-based material or a silanesiloxane-based material, and is a liquid having a viscosity smaller than 10 mPas,
The method for repairing concrete according to claim 1, wherein the uncured concrete is allowed to enter into the irregularities provided on the concrete surface to which an insulating agent is applied. The insulating agent is an alkylalkoxysilane material,
After forming the infiltration layer of the insulating agent by applying the above insulating agent to the removed portion of the concrete of the concrete structure multiple times, the uncured concrete is newly replenished,
2. The method for repairing a concrete structure according to claim 1, wherein during the plurality of times of application, the next application is performed in a state where at least the appearance of the concrete surface is dry. A concrete structure having a steel structure that is a reinforcing bar or a steel pipe is a repair structure for a concrete structure in which the concrete in the restoration part is removed and concrete is newly added to the part from which the concrete has been removed,
A permeation layer in which an insulating agent penetrates from the entire interface between the old concrete part where the concrete of the concrete structure has not been removed and the newly formed new concrete part to the inside of the old concrete part is provided. It electrically insulates the concrete part,
In the longitudinal direction of the steel material, a part of the steel material is inside the new concrete part, and the entire outer periphery of the steel material in the part is inside the new concrete, and the part in contact with the interface on the surface of the steel material is the penetration Reinforcement corrosion prevention structure for concrete structures characterized by being in contact with the layer .

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