JP3318589B2 - Hardened concrete survey method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can easily measure the chloride content contained in hardened concrete, such as a new concrete structure or an existing concrete structure in civil engineering and construction, and can measure the depth of chloride. The present invention relates to a method for investigating hardened concrete in which the chloride content distribution in the direction can be easily known.

[0002]

2. Description of the Related Art In order to properly maintain and manage a concrete structure, it is important to judge the soundness of the target concrete structure by an appropriate method and to take an appropriate countermeasure accordingly.

In order to properly judge the soundness of concrete, not only is it necessary to investigate visible damage such as cracks and peeling, but also to measure the degree of corrosion of reinforcing steel by measuring the natural potential, It is indispensable to measure the chloride content in addition to measuring the depth of formation.

[0004] Chloride adhering to the surface layer of concrete gradually penetrates into the deep part of the concrete over time and accumulates. If the chloride concentration in the concrete is high, this will cause the rebar to corrode significantly.

[0005] Currently, the methods for measuring chloride content are mainly classified into a method using coring and a simple measuring method using a drill. The former method using coring is shown in FIG.
As shown in the figure, when the collected concrete core 50 is returned to the test room, the concrete core 50 is sliced into several pieces, and the sliced concrete core 5 is sliced.
Primary crushing by a crusher and secondary crushing by a pulverizer are performed for each of 0A, 50B... Immersed in a nitric acid solution in a beaker to extract chlorides by boiling. Then, salt analysis such as potentiometric titration is performed for each beaker. This is a method for measuring the chloride content, and if the measured results are plotted on a graph, it is possible to know the chloride content distribution in the depth direction from the surface. On the other hand, the latter simple measurement method using a drill is a method in which drilling is performed with a drill, concrete powder generated at that time is collected, and the chloride content is measured by the salt analysis method described above.

As a simpler method, a silver nitrate solution is sprayed on a concrete core obtained by coring or a concrete powder obtained by drilling, and a chloride penetration depth (presence or absence of chloride penetration at a predetermined depth position). (Referred to as silver nitrate spray method).

[0007]

However, in the case of the method using coring, first, the diameter of the concrete core is relatively large, about 50 mm to 100 mm. It cannot be adopted, and there are many problems, such as the fact that the sampling position is limited due to structural reasons, and the rebar may be cut off during coring. Further, the measurement result cannot be known until after the concrete core is brought back to the test room and the test is performed. Only one point can be measured per slice, making it difficult to determine when there is variation or the like. In addition, there is a problem that a large amount of cost is required for the analysis, and labor and time are required.

[0008] On the other hand, in the case of the simple measuring method using a drill, the diameter of the perforated hole can be reduced, and the damage to the existing concrete structure is relatively small, but the coarse aggregate powder is also mixed. However, there are problems that the measurement accuracy is inferior to the method using a coring, and that it is difficult to grasp the permeation distribution of chloride.

In the case of the simplest silver nitrate spraying method, only the permeation depth can be grasped, but the quantitative measurement of the chloride content cannot be performed. In some cases, it is difficult to determine whether an object is real.

Accordingly, a main object of the present invention is to make it possible to easily and accurately measure the chloride content impregnated in hardened concrete even on site while minimizing the effect on the concrete structure. Another object of the present invention is to provide a method for investigating hardened concrete, which has the advantage that the chloride content distribution in the depth direction can be easily and accurately determined.

[0011]

According to the present invention, there is provided a first step of forming a hole in hardened concrete by perforating, and spraying or applying a reagent for fluorescence determination on the inner wall of the perforated hole. A second procedure of irradiating the hole wall with excitation light of a specific wavelength to measure the intensity of the reflected light, and a chloride based on the correlation between the previously obtained reflected light intensity and the chloride content. And a fourth procedure for determining the content.

In this case, a laser beam is preferably used as the excitation light having the specific wavelength, and a fluorescent dye solution is preferably used as the fluorescent indicator. Further, by performing the chloride content measurement at a plurality of locations in the concrete depth direction, it is possible to easily obtain the chloride content distribution in the depth direction.

Preferably, the diameter of the hole formed by the drilling is set to 20 mm or less in consideration of damage to the concrete structure.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for measuring a chloride content according to the present invention will be described in detail according to a measuring procedure.

First, as shown in FIG. 1, a predetermined portion of a concrete structure 1 to be measured is drilled with a drill 2. The perforation depth L is about 100 mm when examining the chloride content distribution in the depth direction, and about 3 to 5 cm for the fogging when only the chloride content at the reinforcing bar position is to be known. Is preferably 20 mm or less in consideration of damage to the concrete structure 1. As the drill 2 to be used, it is desirable to use a drill dedicated to drilling concrete such as a pilot hole for driving an anchor. In order to minimize adverse effects on the surroundings, drilling is performed by rotation without hitting as much as possible. To do.

After the small holes 3 are formed by drilling, the concrete powder at the time of drilling is removed by an air gun or the like.
A fluorescent quantification reagent is sprayed uniformly on the inner wall of the small hole 3 in the depth direction. In the operation, as shown in FIG. 2, the device mounting table 4 is fixed to the small hole 3 forming site by the anchor bolts 5, 5.
A spray tube feeding device 6 capable of feeding and pulling back the spray tube 7 at a predetermined speed is installed on the device installation table 4, and the inner wall of the small hole 3 is uniformly sprayed with the fluorescent indicator. The spray tube 7
Is provided with a swivel 7b at the rear end and an injection nozzle 7a at the tip. The spray tube feeding device 6 is merely an example of a spray device, and may have any structure as long as it can uniformly spray a reagent for fluorescence determination. In some cases, as shown in FIG. 4, a manual sprayer 8 having a long nozzle 8a may be used. In addition, since it is only necessary that the fluorescence measuring reagent is attached to the rear wall, it may be applied by coating instead of spraying.

As the reagent which can be used as the reagent for the determination of fluorescence, various ones can be mentioned. Is preferably used in terms of fluorescence efficiency and lightness.

After the spraying of the reagent for quantifying the fluorescence onto the hole wall is completed, as shown in FIG. 3, a fluorescence measurement unit 10 is provided with a laser irradiation unit 9 at the tip and a fluorescence luminosity sensor 10 comprising an analyzer and a filter. Insert the tube 11,
Optical fiber 1 for output from laser oscillation / fluorescence measuring device 12
The laser of a specific wavelength sent through the
The fluorescent light sensor 10 irradiates the fluorescent light (reflected light) excited by the laser irradiation while irradiating the fluorescence
Measured by The measured reflected light is taken into the fluorescence measuring device 12 by the input optical fiber 16 and is converted into an electric signal, and is further A / D converted and taken into the analysis computer 13. Analysis computer 1
In FIG. 3, the reflected light intensity (nA) of a predetermined wavelength shown in FIG.
The chloride content at the measurement point is determined based on the correlation data between the measured value and the chloride content (g / m ³ ).

The correlation between the reflected light intensity (nA) at the predetermined wavelength and the chloride content (g / m ³ ) is obtained by a preliminary test conducted in advance. In the so-called fluorescence, molecules in a ground singlet state (lowest energy state) are excited to an excited singlet state (relatively high energy state) by irradiation with excitation light, and immediately thereafter transition (deactivate) to a ground state. This is the light that is emitted. This light is closely related to the excited state level formed between the full band and the conduction band due to the contained small amount of impurities and the amount thereof (in this case, the amount of chloride), and reduces the excitation energy. The way in which the obtained electrons transit to the ground state through several stages depends on the chloride content. As a result, there is a difference in the spectrum of the fluorescence emitted upon deactivation, and a correlation is generated between the reflected light intensity (nA) and the chloride content (g / m ³ ).

The reflected light intensity (nA) and the chloride content (g / g
To obtain the correlation with m ³ ), as shown in FIG. 5 (A), a fluorescent solution is mixed with a salt solution having a predetermined concentration and irradiated with a laser beam having a specific wavelength (λ). Measure the spectrum. Then, the reflected light intensity (ζ ₁ ) corresponding to the predetermined wavelength (λ ₁ ) is obtained. When this test is performed on salt solutions of various concentrations, a correlation diagram between the reflected light intensity at a predetermined wavelength and the chloride content shown in FIG. 5B can be obtained. The wavelength of the laser beam (the specific wavelength) is arbitrarily set within a wavelength range in which strong fluorescence is obtained, and the same wavelength is used in the preliminary experiment and the main measurement. The predetermined wavelength (λ ₁ ) is arbitrarily set within a range where the value of the fluorescence spectrum becomes larger than a certain value.

There are various lasers that can be used, such as a He-Ne laser, a gas laser such as a CO ₂ laser, a solid-state laser such as a YAG laser, and a semiconductor laser, but this apparatus is small in terms of portability. A fixed laser or a semiconductor laser that can be used is preferably used. The preferred value of the laser wavelength (specific wavelength) differs depending on the target element, but in the case of the present chloride measurement, it is set generally within the range of 500 to 650 nm. At present, laser light is most preferable as excitation light, but a mercury lamp, a xenon lamp, or a strong light source having such a spectral line can be used instead.

The laser irradiation and reflected light measurement are performed at a plurality of locations in the small hole depth direction to finally obtain a depth-wise chloride content distribution as shown in FIG. 5 (C). This measurement is performed by the fluorescence measuring tube feeding device 1 indicated by reference numeral 14 in FIG.
4 can be provided for automation.

In the present invention, the content of chlorides impregnated in concrete is specifically measured, but the present measuring method can also quantify other impure compounds from the measuring principle. In addition to the determination of soundness of existing concrete structures, the present invention can be applied to analysis of aggregate used for inspection of alkali-aggregate reaction, and concrete inspection at the time of completion.

[0024]

As described above in detail, according to the present invention, the chloride content impregnated in hardened concrete can be easily and accurately measured on site, and the conventional method by coring can be used. In comparison, the effect on concrete structures is significantly reduced.
In addition, it is possible to measure an arbitrary number of points in the depth direction, and it is possible to easily and accurately know the chloride content distribution in the depth direction.

[Brief description of the drawings]

FIG. 1 is a first procedure diagram of a chloride content measuring method according to the present invention.

FIG. 2 is a second procedure diagram.

FIG. 3 is a third procedure diagram.

FIG. 4 is a diagram showing another method of spraying a reagent for fluorescence quantification.

5 shows the procedure up to chloride content determination, (A) is a fluorescence spectrum diagram, (B) is a correlation diagram between reflected light intensity and chloride content, (C) is chloride in the depth direction It is a content distribution map.

FIG. 6 is a diagram showing a conventional procedure for measuring chloride content by coring.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Concrete structure to be measured, 2 ... Drill, 3 ... Small hole, 4 ... Equipment mount, 5 ... Anchor bolt, 6 ... Spray pipe feeder, 7 ... Spray pipe, 7a ... Injection nozzle, 7b ... Swivel, 9 ... Laser irradiation unit, 10 ... Fluorometer, 11 ... Fluorescence measuring tube, 12 ... Laser oscillation / fluorescence measuring device, 13 ... Computer for analysis

Claims (4)

(57) [Claims] 1. A first procedure for forming a hole in hardened concrete by drilling, a second procedure for spraying or applying a reagent for fluorescence quantification to an inner wall of the drilled hole, and exciting light of a specific wavelength to the wall of the hole. And a fourth procedure for obtaining a chloride content based on a correlation between a previously obtained reflected light intensity and a chloride content. Hardened concrete survey method. 2. The method according to claim 1, wherein the excitation light having the specific wavelength is a laser light,
The method of claim 1 wherein the fluorescent indicator is a fluorescent dye solution. 3. The method for investigating hardened concrete according to claim 1, wherein the chloride content is measured at a plurality of locations in the depth direction of the concrete to obtain a chloride content distribution in the depth direction. 4. The method for investigating hardened concrete according to claim 1, wherein the diameter of the hole formed by the drilling is 20 mm or less.