JP5371100B2 - Sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique of simply determining the internal environment state of a concrete structure or the like. <P>SOLUTION: In determining the internal environment of concrete or the like having an external injection type sensor 10a embedded therein, the aqueous solution in the pores of mortar is incorporated in a gel 50 through a cellophane membrane 60. If the aqueous solution in the pores of mortar is alkaline, the gel 50 shows a reddish purple color. When the coloration state of the gel 50 is detected, light is incorporated in an irradiating optical fiber 11 from a light source and emitted toward the gel 50 from the emitting surface 11a thereof. Then, the light transmitted through the gel 50 from the incident surface 12a of a detecting optical fiber 12 is incorporated in the detecting optical fiber 12 to be analyzed by a detector. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a sensor, for example, a sensor capable of evaluating a chemical environment around a sensor using an indicator.

  The neutralization of concrete is a phenomenon in which the alkalinity of concrete is lost due to carbon dioxide in the atmosphere. As a result, since the function with respect to the reinforcing bars is reduced, the expansion due to the occurrence of rust occurs and the concrete is cracked, so that the strength of the building is reduced. Currently, in order to measure the progress of neutralization, a chemical method such as a simple measurement method using phenolphthalein, a thermal analysis method, an X-ray diffraction method is generally used by collecting a part of the structure. ing. However, these methods are undesirable because they damage the structure. Therefore, establishment of a method for predicting and detecting the neutralization of concrete in a non-destructive manner is required. Research to predict the progress of neutralization of concrete has been made for a long time, and many mathematical methods for predicting the progress of neutralization have been proposed, but in order to apply the prediction to actual structures There are still challenges. Therefore, in reality, it is necessary to actually measure the neutralization of concrete.

  For example, for the purpose of establishing a system that can monitor the neutralization of concrete in a non-destructive manner, the principle of a sensor that combines a hydrophilic gel with an added pH indicator and an optical fiber has been devised. A technique for monitoring has been proposed (see Non-Patent Document 1). In this technique, a gel containing a pH indicator is installed in a sensor and embedded in a concrete structure. By setting it as such a structure, the color which the gel exhibited can be detected with an optical fiber, and even if it is an environment like the inside of a concrete structure, the pH change around a sensor can be grasped | ascertained.

  In addition, an environmental sensor in which a sol / gel substance and an optical fiber are combined has been proposed (see Patent Document 1). In this technique, grooves are formed in a predetermined substrate, and a sol-gel substance containing a chemical indicator is filled in these grooves, and then cured and adhered to the substrate. The groove is formed to facilitate optical coupling of the optical fiber cable to the sol-gel sensor element. At this time, light is coupled from the optical fiber cable to the sol-gel sensor element.

JP 2008-50176 A

Serizawa, 3 others, “Examination of pH sensor for detecting neutralization of concrete”, “Reports on papers for repair, reinforcement and upgrade of concrete structures, Volume 7”, Japan Society for Materials Science, p.391-396

  By the way, in the technique disclosed in Non-Patent Document 1, it is possible to reduce the drying of the gel and the elution of the indicator to some extent after being embedded in the mortar. There was room for improvement in maintaining it, and it was required to introduce another technology. Moreover, even in the technique disclosed in Patent Document 1, sensing over a long period of time and further embedding in a structure such as concrete are not considered, and there is a problem that it is difficult to apply as it is. there were.

  This invention is made | formed in view of such a condition, Comprising: It aims at solving said subject.

The gist of the invention of claim 1 is as follows:
A sensor embedded in a concrete structure and measuring the state of the internal environment of the concrete structure,
Storage means capable of storing reagents and liquids;
A light receiving means for receiving light from the reagent;
Supply means for supplying a liquid to the containing means;
With
The accommodating means, the light receiving means, and the supplying means are configured integrally.
Comprising a plastic body integrally comprising the housing means, the light receiving means and the supply means;
The accommodating means is a slit formed in a part of the precursor and a gel-like body that is disposed in the slit and can contain the reagent,
An irradiation means for irradiating light to the reagent arranged in the storage means;
The irradiation unit is configured integrally with the housing unit, the light receiving unit, and the supply unit,
The light receiving means is an optical fiber, receives light from the reagent at one end and outputs it to the other end,
The irradiation means is an optical fiber, acquires light from one end, and irradiates the acquired light from the other end to the reagent arranged in the storage means,
The light irradiation surface of the optical fiber constituting the irradiation means and the light receiving surface of the optical fiber constituting the light receiving means are disposed substantially opposite to each other.
The slit is formed by a high-speed precision cutting machine.
The gist of the invention of claim 2 is as follows:
The sensor according to claim 1, wherein the sensor has a substantially circular cross section, and the irradiation surface and the light receiving surface are eccentric.
The gist of the invention of claim 3 is that
3. The sensor according to claim 1, further comprising outer covering means that covers the outside of the housing means and has a property of transmitting a predetermined substance.
The gist of the invention of claim 4 is as follows:
The light irradiation surface of the optical fiber constituting the irradiation means and the light receiving surface of the optical fiber constituting the light receiving means are disposed substantially opposite to each other,
The light irradiation surface of the optical fiber constituting the irradiation means and the light reception surface of the optical fiber constituting the light receiving means are arranged substantially adjacent to each other and facing the same direction. It exists in the sensor of Claim 1.
The gist of the invention of claim 5 is as follows:
5. The sensor according to claim 1, further comprising a discharge unit capable of discharging the substance of the storage unit to the outside.
The subject matter of claim 6 is as follows:
6. The sensor according to claim 5, wherein the discharging means is capable of supplying materials stored in the storing means from the outside.
The gist of the invention of claim 7 is that
The said reagent exists in the sensor in any one of Claim 1 to 6 which reacts with the chemical substance of acidic, alkaline, a chloride ion, or a sulfate ion, and is colored.
The gist of the invention described in claim 8 is as follows:
The reagent is a pH indicator;
8. The sensor according to claim 7, wherein the liquid supplied by the supply means is a solution containing a pH indicator.

  According to the present invention, it is possible to easily grasp the environmental state inside an object such as a structure.

It is the figure which showed typically the example of application of the sensor in a base technology. It is the figure which showed schematic structure of the sensor in a base technology. It is the figure which showed the visible spectrum change of the transmitted light when a sensor was embedded in the mortar piece and immersed in hydrochloric acid in a base technology. It is the figure which showed the state inside a mortar piece when a sensor was embed | buried in a mortar piece and immersed in hydrochloric acid in a premise technique. It is the figure which showed the result verified about the characteristic of the cellophane film | membrane utilized for the sensor based on the 1st Embodiment of this invention. It is the figure which showed typically the external injection type sensor based on the 1st Embodiment of this invention. It is the figure which showed the spectrum change after embedding in the mortar in the external injection type sensor based on the 1st Embodiment of this invention. It is the figure which showed the time-dependent change of the transmittance | permeability of 550 nm in the embedding period in the external injection type sensor based on the 1st Embodiment of this invention. It is the figure which showed the spectrum change after inject | pouring a phenolphthalein solution from the injection tube 13 based on the 1st Embodiment of this invention. It is the figure which showed typically the self-replenishment type sensor based on the 2nd Embodiment of this invention. It is the figure which showed the spectrum change after embedding the self-replenishment type sensor based on the 2nd Embodiment of this invention in mortar. It is the figure which showed the time-dependent change of the transmittance | permeability of 550 nm during the embedding period in the self-replenishment type sensor based on the 2nd Embodiment of this invention. It is the figure which showed typically the self-replenishment type sensor based on the modification of this invention.

  Next, modes for carrying out the present invention (hereinafter simply referred to as “embodiments”) will be specifically described with reference to the drawings. Below, the detection method of the pH state inside concrete is first demonstrated as a premise technique, and a specific technique is demonstrated continuously.

<Prerequisite technology>
FIG. 1 is a diagram schematically showing an application example of the sensor 100 in the base technology, and the same applies to first and second embodiments described later. In the concrete, as the cement hydrates, calcium hydroxide is generated, and the liberated calcium hydroxide is dissolved in the aqueous solution of voids in the concrete. For this reason, the aqueous solution in the space is a saturated aqueous solution of calcium hydroxide. Therefore, a sensor 100 including a polymer gel containing a pH indicator (hereinafter simply referred to as “gel”) is embedded in the concrete. Then, the aqueous solution in the void enters the sensor gel together with the dissolved ions, and the pH indicator retained in the gel reacts and colors. That is, the color of the gel changes according to the surrounding pH. The color change due to pH is measured using a spectrophotometer (detector) through the optical fiber 110.

  Here, polyvinyl acetamide was used for the gel. Phenolphthalein was used as the pH indicator. Phenolphthalein has a color gamut of pH 7.8 (colorless) -10.0, (reddish purple), and the color development is vivid and easy to understand the difference, so it is suitable for determining neutralization. The pH indicator is not limited to phenolphthalein, and for example, BTB (bromothymol blue), BPB (bromophenol blue), thymolphthalein and the like can be used. Furthermore, in order to detect the state in concrete, reagents, such as a fluorescein, silver nitrate, cobalt chloride, can also be used besides pH indicator. These reagents may be used in combination. Furthermore, a reagent that colors a chemical substance such as chloride ion or sulfate ion may be used. Since chemical substances such as chloride ions and sulfate ions have a great influence on concrete deterioration and rebar corrosion, it is possible to detect concrete deterioration and the like by detecting these substances.

  0.3 g of dried granular gel is added to 30 ml of ethanol solution of 1% phenolphthalein and swollen for 10 hours while stirring with a stirrer. When the swollen gel was immersed in an aqueous solution of sodium hydroxide having a pH of 12.6 corresponding to the environment of the non-neutralized concrete, it turned red to the center of the gel in about 5 minutes. Then, when it was immersed in water, it faded in about 2 hours. From this result, the gel is reversibly colored according to the surrounding pH change, and neutralization inside the concrete can be detected. Therefore, by connecting the end of the optical fiber to a visible light source and a visible spectrometer, respectively, and monitoring the visible spectrum of the transmitted light that has passed through the gel, it is possible to easily grasp the pH change around the sensor.

  FIG. 2 shows a schematic configuration of the pH sensor (sensor 100). Specifically, a manufacturing procedure of the sensor 100 is simply shown. As shown in FIG. 2A, an optical fiber 110 having a predetermined length (specifically, 80 cm) is prepared, and a central portion 6 cm is embedded with a vinyl ester resin (plastic) body 120. The optical fiber 110 is a PMMA (polymethyl methacrylate resin) step index type multimode optical fiber having a core diameter / cladding diameter of 0.98 / 1.0 (mm). Then, as shown in FIG. 2B, a slit 130 having a width of about 1 mm is formed using a high-speed precision cutting machine. Then, as shown in FIG.2 (c), the gel 150 is arrange | positioned to the slit 130, and the gel 150 is fixed with a cellophane film | membrane (not shown). Furthermore, a connector is attached to both ends of the optical fiber 110, and an infrared visible spectrophotometer (USB2000 manufactured by Ocean Optics) is connected to the connector, and the color change of the gel 150 is detected by the transmitted light in the visible light region. The

  In FIG. 3, when this sensor 100 is embedded in a mortar piece (100 × 100 × 20 mm) and immersed in hydrochloric acid at 50 ° C. and 10% for an acceleration experiment, the transmitted light transmitted through the gel 150 of the sensor 100 is shown. Shows visible spectrum change. Immediately after the start of immersion, a relatively large absorption peak is observed in the vicinity of 560 nm, which indicates that the gel 150 of the sensor 100 is colored reddish purple. This is because the pore water in the mortar (cement) is originally about pH 12-13. This absorption peak gradually decreased from about 32 hours after immersion, and almost disappeared after 38 hours. When the mortar piece after 38 hours was split and the cross section was observed, it was found that hydrochloric acid infiltrated from the surface of the mortar reached the embedded depth of the sensor 100 as shown in FIG. That is, it is considered that the pore water around the sensor 100 was neutralized by the entering hydrochloric acid, and the gel of the sensor 100 was changed from reddish purple to colorless and transparent. From this result, it was confirmed that this sensor 100 can be applied to the detection of the pH change of the concrete pore water accompanying the penetration of the deterioration factor.

  Next, in order to confirm whether the phenolphthalein solution on the mortar is colored through the cellophane film, the following experiment was performed. The mortar was cast in a 60 mm × 90 mm mold with a thickness of about 8 mm, a cellophane film was spread on the mortar, and a 0.01 g / ml-EtOH phenolphthalein solution was poured to a depth of about 2 mm. It was confirmed that the phenolphthalein solution was poured into a mortar covered with a cellophane film immediately after placement and a mortar cured for 100 hours. The mortar immediately after placement was very rich in water, the phenolphthalein solution quickly colored, and the magenta color became darker with time. On the other hand, the phenolphthalein solution of mortar cured for 100 hours slowly changed color and its coloration was weak. Moreover, although the vicinity of the cellophane film is colored, the entire phenolphthalein solution is only slightly colored. Immediately after the placement, after 100 hours of curing, no significant change in appearance was observed after 1 hour after the injection of the phenolphthalein solution.

  Next, the optical fiber sensor with a slit which does not put gel in the above-mentioned phenolphthalein solution was immersed, and the change in spectrum at this time was measured. The transmitted light before immersing the sensor in a phenolphthalein solution was used as a reference value.

  The result using the mortar immediately after placing is shown in FIG. 5 minutes after adding the phenolphthalein solution, absorption was observed at 550 nm, and after 1 hour, the transmittance at 550 nm was zero. It can be seen that when the mortar immediately after placement is used, the response time is fast and the phenolphthalein is also clearly colored.

  As a result of verifying the results using mortar after 100 hours of placement, as described above, coloration was slowly generated from phenolphthalein in the vicinity of the cellophane film, and as time passed, coloration began from the vicinity of cellophane. It spread throughout the phenolphthalein. Therefore, it took about 2 hours until clear absorption was observed at 550 nm in the transmitted light spectrum. Furthermore, the absorption is further increased after 3 hours. The mortar poured with the phenolphthalein solution was covered with a wrap to prevent drying, but the ethanol of the phenolphthalein solution evaporated and absorbed into the mortar over the course of 2 hours and 3 hours. The increase in the concentration of phenolphthalein is also considered to be a cause of the strong color development.

  From the above results, it was confirmed that the phenolphthalein solution on the mortar was colored through the cellophane film. Therefore, if a phenolphthalein solution is supplied to the slit portion of the optical fiber sensor with slit, it is considered that the mortar is colored through the cellophane film and can be measured as transmitted light.

Therefore, based on the above prerequisite technology, we introduced a technology that realizes long-term use and improved the sensor. Hereinafter, an external injection type sensor that injects phenolphthalein from the outside as a first embodiment, and a self-supply type sensor that replenishes moisture to the slit part as a second embodiment will be described.
<First Embodiment>

  FIG. 6 is a view schematically showing the external injection type sensor 10a according to the present embodiment. FIG. 6 (a) is an external injection type sensor 10a in which the gel 50 is disposed in the slit 30, and FIG. 6 (b) shows the external injection type sensor 10a in a state where the gel 50 and the cellophane film 60 are removed. As shown in the figure, the external injection type sensor 10a includes a vinyl ester resin precursor 20 in which slits 30 are formed, an irradiation optical fiber 11 that irradiates light onto a gel 50 disposed in the slits 30, and a gel 50. Detection optical fiber 12 for obtaining the color of the liquid, an injection tube 13 for injecting the phenolphthalein solution into the gel 50 as needed, and a discharge for discharging excess phenolphthalein solution or internal air. Tube 14.

  Then, the internal environment such as concrete (mortar) in which the external injection type sensor 10 a is embedded, that is, the aqueous solution in the mortar pores is taken into the gel 50 through the cellophane film 60. If the aqueous solution in the mortar pores is alkaline, the gel 50 is colored purple. When the color state of the gel 50 is detected, light is taken into the irradiation optical fiber 11 from the light source, and light is output from the emission surface 11 a toward the gel 50. And the light which permeate | transmitted the gel 50 from the entrance plane 12a of the optical fiber 12 for a detection is taken in into the optical fiber 12 for a detection, and is analyzed with a detector.

  When the gel 50 is assumed to be dry due to the outflow of the phenolphthalein solution to the concrete, the gel 50 is replenished with the phenolphthalein solution via the injection tube 13. Further, the excess phenolphthalein solution at the time of replenishment is discharged from the discharge tube 14 to the outside. Thus, by providing both the injection tube 13 and the discharge tube 14, not only the discharge of the surplus solution, but also the replacement and maintenance of substances for keeping the inside of the slit 30 (gel 50) in an appropriate state. Can be done effectively. Specifically, it is assumed that the sensing ability is deteriorated by bubbles entering the gel 50, that is, the portion where the light supplied by the irradiation optical fiber 11 absorbs the wavelength. In such a case, the discharge tube 14 can function as a so-called air nuisance means. In addition, for example, the inside of the slit 30 can be cleaned or the gel 50 can be refilled in some cases.

  The manufacturing method and materials used for the external injection type sensor 10a are the same as those shown in FIG. Specifically, a plastic optical fiber having an inner diameter / outer diameter of 1.0 / 2.0 (mm) is prepared in a desired length, and a polyethylene tube is prepared in a desired length. These two centers 6 cm are embedded in a vinyl ester resin precursor 20 and then a slit 30 having a width of about 2 mm is formed using a high-speed cutter. As the slit 30 is formed, the optical fiber and the polyethylene tube are also cut. Thus, the optical fiber is divided into the irradiation optical fiber 11 and the detection optical fiber 12. Similarly, the polyethylene tube is divided into an injection tube 13 and a discharge tube 14. The width of the slit 30 is set in consideration of the size of the gel 50 arranged in the slit 30, the detection characteristics of transmitted light, and the like.

  Thereafter, at each end of the irradiation optical fiber 11 and the detection optical fiber 12 extending from the body 20, the polyethylene jacket is peeled off by about 1.5 cm, a spectroscope connector (not shown) is attached, and the end faces are Hot plate processing is performed. A cellophane film 60 is attached to the slit 30 of the manufactured external injection type sensor 10 a so as to cover the slit 30.

  The external injection type sensor 10a is embedded in a mortar of 100 mm × 100 mm × 20 mm, a 0.01 g / ml-EtOH phenolphthalein solution is injected 100 hours after the implantation, and the result of measuring the spectral change will be described below.

  FIG. 7 shows the change in spectrum from embedment in mortar to 362 hours later. In addition, FIG. 8 shows a change with time in transmittance at 550 nm during the burying period. 1 hour after embedding, the transmittance of 550 nm began to decrease due to the coloration of the gel 50, and eventually became zero. Thereafter, time was allowed until the gel 50 was sufficiently dried. When the spectrum after 362 hours is observed, the absorption at 550 nm is not observed, so it is considered that the gel 50 dries out of the optical path at this point.

  Therefore, 0.01 g / ml-EtOH phenolphthalein solution was injected from one side of the injection tube 13 with a cylinder until the phenolphthalein solution came out from the discharge tube 14. The spectrum change after the injection is shown in FIG. 9, and the change around 400 hours in FIG. 8 is shown. Here, the time when the phenolphthalein solution was injected was set to 0 minutes. As soon as the phenolphthalein solution was injected, the transmittance near 550 nm decreased and became zero after 30 minutes.

  This is probably because the gel 50 in the slit 30 swells and rides on the optical path again. After that, when the burying of the external injection type sensor 10a was continued and the detection of the spectrum change was continued, the transmittance increased again 118 hours later (after 527 hours buried) as shown in FIG. . And it fell to 0 in about 2 hours after inject | pouring a phenolphthalein solution. Thereafter, no change was observed in the spectrum until 574 hours. Therefore, in order to observe the state of the gel 50 at this time, the mortar was split, the gel 50 was taken out and the state was confirmed. At this time, it was confirmed that the gel 50 taken out from the external injection type sensor 10a kept water and developed a color when compared with a gel which was buried in mortar and then dried without supplying phenolphthalein and removed from the optical path. did it.

  From the above results, it was confirmed that when the phenolphthalein solution was supplied, the gel 50 was swollen again and the transmittance was lowered. In the external injection type sensor 10a, the phenolphthalein solution does not always exist in the slit 30, and the phenolphthalein is injected every measurement, so that the external injection type sensor 10a is more suitable for regular monitoring than regular monitoring. In particular, it is realistic to inject a phenolphthalein solution for each measurement and wait for a response rather than being always supplied with a phenolphthalein solution for regular monitoring over a long period of order of several decades. It is very suitable for such long-term monitoring.

  Next, the external injection type sensor 10a with the gel 50 removed is embedded in a mortar of 100 mm × 100 mm × 20 mm, and a spectral change is measured by injecting 0.01 g / ml-EtOH phenolphthalein solution 100 hours after placement. The results will be described below.

  About 100 ml of the phenolphthalein solution was injected into the slit 30 through the injection tube 13 using a syringe 100 hours after the placement. As it was injected, the phenolphthalein solution that passed through the slit 30 came out from the discharge tube 14 disposed on the opposite side. From this, it was confirmed that the slit 30 was filled with the phenolphthalein solution.

Therefore, since the mortar around the slit 30 is dry and takes a long time to become alkaline, the entire specimen is immersed in water so that the alkaline solution in the mortar pores can easily permeate the cellophane film. Then, the spectral change was observed. Then, after immersing in water, the transmittance at 550 nm slightly decreased after 116 hours. After that, there was no change in the spectrum, and it was confirmed that the phenolphthalein that had entered the slit was colored.
<Second Embodiment>
In the present embodiment, a self-replenishment type sensor 10b that replenishes the phenolphthalein solution itself when the gel 50 of the slit 30 is dried will be described.

  FIG. 10 shows a schematic configuration of the self-replenishment type sensor 10b according to the present embodiment, and FIG. 10 (a) shows a state where the gel 50 is disposed in the slit 30 and covered with the cellophane film 60. FIG. 10B shows a state where the gel 50 and the cellophane film 60 are removed. The self-replenishment type sensor 10b of this embodiment has a configuration similar to that of the external injection type sensor 10a described in the first embodiment, and the same components are denoted by the same reference numerals and description thereof is omitted as appropriate.

  As shown in the figure, the self-replenishment type sensor 10b of the present embodiment has a configuration in which the discharge tube 14 is removed unlike the external injection type sensor 10a. That is, the injection tube 13 is embedded in the slit 30 only on one side, and the injection tube 13 is always filled with the phenolphthalein solution. When the gel 50 in the slit 30 is dried, the phenolphthalein solution is supplied from the injection tube 13 to the gel 50.

  The self-replenishing sensor 10b was embedded in mortar under the same conditions as in the first embodiment, and the change in spectrum was measured. The injection tube 13 is filled with a phenolphthalein solution at the stage of filling the slit 30 with the gel 50. The tip of the injection tube 13 on the extending side (the side opposite to the slit 30) is connected to a syringe containing 0.01 g / ml-EtOH phenolphthalein solution. Phthalein is supplied.

  FIG. 11 shows the spectral change from 649 hours after the self-replenishing sensor 10b is embedded in the mortar. Further, FIG. 12 shows a change with time in transmittance at 550 nm during the burying period. 1 hour after embedding, the transmittance of 550 nm began to decrease due to the coloration of the gel 50, eventually becoming 0, and maintaining 0 even after 650 hours had passed. In addition, it is known that the transmittance starts to increase in 96 hours when moisture is not replenished from the outside of the mortar. Compared with the result, it can be seen that the gel 50 is colored for a long time in the self-replenishment sensor 10b. .

  Further, after 845 hours from the burial, the transmittance at 550 nm increased to about 30%. Therefore, a phenolphthalein solution was injected from the injection tube 13 using a syringe. In addition, unlike the external injection type sensor 10a, the self-replenishment type sensor 10b is assumed to be difficult to inject the phenolphthalein solution with a syringe because there is no discharge tube 14, but there is a slight reaction force (resistance to push back). In some cases, the syringe was pushed and phenolphthalein was injected into the slit 30. When the phenolphthalein solution was injected into the slit 30, the transmittance decreased again and returned to zero. From this, it is considered that the replenishment of the gel 50 did not catch up and the phenolphthalein solution was injected from the outside into the place where the gel 50 was drying, and the gel 50 was swollen again. After that, when the burial was continued, the transmittance increased again in 1102 hours, and the phenolphthalein solution was injected again after 1150 hours. When phenolphthalein was injected, the transmittance decreased to 0 again. In order to observe the state of the gel 50 at this time, the mortar was split and the gel 50 was taken out, and it was confirmed that the gel 50 was swollen while retaining moisture.

  It was confirmed that the color of the gel 50 collected from the external injection sensor 10a was weaker than that of the gel 50 collected from the self-supplying sensor 10b. This is because phenolphthalein is not always supplied in the external injection type sensor 10a, and the inside of the slit 30 is completely dried, so that it is difficult for the alkaline solution in the mortar pores to be taken into the phenolphthalein injected. It seems to be because it has become.

  From these results, the self-replenishing sensor 10b can retain moisture in the mortar for a long period of time, and even if the transmittance at 550 nm temporarily rises, it decreases again by injecting phenolphthalein. Was confirmed. It is considered that the gel 50 is swollen again by the phenolphthalein solution injected from the outside when self-replenishment does not catch up with the drying of the gel 50 and deviates from the optical path.

As described above, according to the present embodiment, the following effects can be obtained.
By using the current appearance inspection of the structure and monitoring by the above sensors (external injection type sensor 10a, self-replenishment type sensor 10b sensor) in combination, it is possible to determine the timing of structural performance degradation (steel corrosion, etc.) The accuracy of prediction is improved, and accurate repair and dismantling can be performed at an optimal time.
In daily inspections and periodic inspections, data collection is stopped until the next inspection, but by constantly monitoring using the self-replenishment type sensor 10b, missed inspection information is reduced.
The external injection type sensor 10a can be used if phenolphthalein is injected only at the time of measurement, and the maintenance cost can be reduced.
By using the self-replenishment type sensor 10b, it is possible to easily perform monitoring at a high place where access is difficult and where a scaffold must be assembled, or at a place where humans are difficult to enter, such as radiation and a toxic atmosphere.
It can be used for Kushiro where appearance observation is impossible.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it is understood by those skilled in the art that various modifications can be made to each of those components and combinations thereof, and such modifications are also within the scope of the present invention. Below, such a modification is shown.

  FIG. 13 is a diagram showing a schematic configuration of a self-replenishment type sensor 10c according to a modification. As shown in the figure, the irradiation optical fiber 11, the detection optical fiber 12, and the injection tube 13 are disposed substantially adjacent to the slit 30 on the same side. When the gel 50 receives the light output from the irradiation optical fiber 11, when it is alkaline, the gel 50 is colored in magenta. At this time, the light diffused inside the gel 50 is on the detection optical fiber 12 side. Is also output. Therefore, even if the irradiation optical fiber 11 and the detection optical fiber 12 are arranged on the same side with respect to the slit 30, the color state of the gel 50 can be detected. According to the self-replenishment type sensor 10c having this configuration, since the member extending from the driving body 20 is only on one side, the degree of freedom in embedding the self-replenishment type sensor 10c in the structure is improved.

  Although not shown, as another modification, a light source such as an LED light is attached to the wall surface of the slit 30 instead of the irradiation optical fiber 11 as a means for irradiating the gel 50 with light. A configuration in which electric power is supplied by a power source arranged in the vicinity may be used. In recent years, a non-contact power supply technology and a power saving technology have advanced, and by using the technology, the gel 50 can be irradiated with light for a relatively long period of time. In addition, it is good also as a structure which uses the detection means which detects the coloration state of the gel 50 instead of the detection optical fiber 12, and outputs the acquired information by radio | wireless etc. Furthermore, when the indicator contained in the gel 50 has the property of self-luminous, means for irradiating the gel 50 with light is not necessary. In the above-described embodiment, the deterioration state or the like of the concrete is determined by detecting the alkalinity, but naturally the indicator may be different depending on the environment to be measured. Furthermore, the structure which detects not only visible light but an ultraviolet-ray and infrared rays may be sufficient. In addition, the cellophane film 60 is used to keep the gel 50 in the slit 30, but the present invention is not limited to this. A substance (for example, gel 50) that can transmit a substance exhibiting the characteristics of the surrounding environment through the cellophane film 60 and the like through the cellophane film 60 from the outside of the external injection sensor 10a and the like, and appropriately serves as an indicator medium (for example, gel 50). If it can be placed, it can be selected appropriately. Furthermore, as long as the solution containing the reagent appropriately stays in the slit 30 and has a characteristic that the color change is detectable, the gel 50 may be omitted.

10a External injection type sensor 10b, 10c Self-replenishment type sensor 11 Irradiation optical fiber 12 Detection optical fiber 13 Injection tube 14 Ejection tube 20 Radiator 30 Slit 50 Gel 60 Cellophane film

Claims (8)

A sensor embedded in a concrete structure and measuring the state of the internal environment of the concrete structure,
Storage means capable of storing reagents and liquids;
A light receiving means for receiving light from the reagent;
Supply means for supplying a liquid to the containing means;
With
The accommodating means, the light receiving means, and the supplying means are configured integrally.
Comprising a plastic body integrally comprising the housing means, the light receiving means and the supply means;
The accommodating means is a slit formed in a part of the precursor and a gel-like body that is disposed in the slit and can contain the reagent,
An irradiation means for irradiating light to the reagent arranged in the storage means;
The irradiation unit is configured integrally with the housing unit, the light receiving unit, and the supply unit,
The light receiving means is an optical fiber, receives light from the reagent at one end and outputs it to the other end,
The irradiation means is an optical fiber, acquires light from one end, and irradiates the acquired light from the other end to the reagent arranged in the storage means,
The light irradiation surface of the optical fiber constituting the irradiation means and the light receiving surface of the optical fiber constituting the light receiving means are disposed substantially opposite to each other.
The slit is formed by a high-speed precision cutting machine.   The sensor according to claim 1, wherein the sensor has a substantially circular cross section, and the irradiation surface and the light receiving surface are eccentric.   The sensor according to claim 1, further comprising an outer covering unit that covers the outside of the housing unit and has a characteristic of transmitting a predetermined substance. The light irradiation surface of the optical fiber constituting the irradiation means and the light receiving surface of the optical fiber constituting the light receiving means are disposed substantially opposite to each other,
The light irradiation surface of the optical fiber constituting the irradiation means and the light reception surface of the optical fiber constituting the light receiving means are arranged substantially adjacent to each other and facing the same direction. The sensor according to claim 1.   The sensor according to any one of claims 1 to 4, further comprising discharge means capable of discharging the substance in the storage means to the outside.   The sensor according to claim 5, wherein the discharging unit can supply the material stored in the storing unit from the outside.   The sensor according to any one of claims 1 to 6, wherein the reagent is colored by reacting with an acidic, alkaline, chloride ion or sulfate ion chemical substance. The reagent is a pH indicator;
The sensor according to claim 7, wherein the liquid supplied by the supply unit is a solution containing a pH indicator.

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