JP2001215195A - Concrete structure and method for detecting deterioration thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deterioration detection method for easily performing the investigation of deterioration over the whole of a concrete struture and the concrete structure of which the deterioration is easily detected. SOLUTION: In a method for detecting the deterioration of the concrete structure, a fluorescent carrier generating fractal luminescence is bonded to the surface of concrete, and the deterioration of concrete is detected by the fluorescence emitted from the fluorescent carrier accompanied by the damage of concrete.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for detecting deterioration of a concrete structure and a concrete structure.

[0002]

2. Description of the Related Art As a method of investigating the deterioration of a concrete structure, a method of directly taking a core specimen from the structure and examining its strength by a compression test and a method of examining the strength of the surface of the structure are described. There are methods for visually inspecting the shape and width of cracks and for measuring the propagation speed of ultrasonic waves to estimate the degree of deterioration. Normally, periodic inspections are performed in the latter form rather than the former, which is a destructive inspection.However, taking long bridges as an example, if there is no passage for management, use binoculars from the ship. Use it to investigate, or to start investigating only after actually laying a scaffold,
The labor and cost spent for visual inspection is a heavy burden on the side of managing the structure.

Recently, a method has been developed in which a strain gauge is attached to a place where the occurrence of stress or crack is predicted, and a crack is electrically detected, and a technique of optically measuring displacement using an optical fiber has been developed. However, the measurement points were point or partial, and it was difficult to inspect the entire structure.

Accordingly, an object of the present invention is to provide a deterioration detection method for easily performing a deterioration investigation on the entire concrete structure and a concrete structure with which deterioration can be easily detected.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found a new method that is effective for investigating the deterioration of concrete structures. In this method, the degradation occurring in a concrete structure can be detected not only from a “partial” viewpoint but from a “surface” viewpoint by applying the fractoluminescence.

[0006] That is, the solution of the present invention is characterized in that a fluorescent carrier that generates fructoluminescence is attached to the concrete surface, and deterioration of the concrete is detected by the fluorescence emitted from the fluorescent carrier accompanying the breakage of the concrete. The method for detecting deterioration of a concrete structure. Further, a solution of the present invention is a concrete structure characterized in that a fluorescent carrier that emits fluorescence upon destruction is attached to a concrete surface.

Fractoluminescence refers to a phenomenon in which surrounding atoms are excited by energy generated when an object is damaged, and the energy released when excited electrons return to the ground state again appears as fluorescence. When a concrete structure reaches the limit of its proof stress, fine cracks first occur on the surface of the concrete that cannot withstand the tensile stress. In this case, if the surface of the concrete is covered with a fluorescent carrier that causes fructoluminescence, the fluorescent carrier emits fluorescence due to energy due to such cracks. Therefore, the observer can observe the crack not by the fine surface crack but by the fluorescent color emitted therefrom. I understand.

[0008] Examples of the fluorescent substance causing fructoluminescence include rare earth elements exemplified by europium and the like. In order for rare earth elements to produce fluorescence,
Rather than being attached alone with a rare earth element, a structure in which a rare earth element is added to the carrier using a crystal structure or the like as a carrier (hereinafter, referred to as
It is preferably attached to the concrete surface as “fluorescent carrier”. As carriers, feldspar and Ba
Examples include a crystal structure such as FX, a glass phase, or a composite thereof.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. First, a fluorescent carrier is prepared by adding a rare earth element to the constituent elements of feldspar and firing, and the fluorescent carrier is pulverized to obtain a powdery fluorescent carrier. The powder of the fluorescent carrier can be applied to the surface of the concrete structure by various means. However, in order to more reliably detect the deterioration, it is desirable to apply the powder uniformly to the concrete surface. For example, it is preferable to apply by the following two methods.

First, as a first method, the fluorescent carrier is mixed with a glass paint such as methylsiloxane or an organic paint such as acrylic resin.
The surface of the concrete structure is applied by brushing or spraying.

As a second method, the fluorescent carrier is similarly mixed with a paint and then applied to the inside surface of a concrete mold in advance, or a thin film containing the fluorescent carrier is prepared in advance and applied to the inside surface of the mold. After putting concrete,
This is a method of transferring from the surface of the mold to the surface of the structure when removing the mold.

In order for the observer to observe the crack as a color, it is desirable that the fluorescent carrier keeps emitting afterglow for a long time. As the structure of such residual light out continued easy carriers include SrA1 ₂ O _4, CaA1 crystal structure, such as ₂ O _4.

In addition, a specific wavelength may be effective for detection depending on the detection instrument or environment. In this case, a change in color is rare earth element ion having a large number of electronic levels,
For example, by using Pr ³⁺ , Er ^3+, etc., the wavelength of the coloring light can be adjusted.

Table 1 shows the composition of the constituent elements of feldspar and the rare earth elements, and the color of the fractoluminescence thereof.

[0015]

[Table 1]

It is also considered that it may be preferable to take measures to prevent anxiety to ordinary people when fluorescent light is generated on the surface of the concrete structure. In such a case, it is preferable to adopt a method that can be detected only by secondarily irradiating an ultraviolet ray or an infrared ray, that is, Ba.
FX (X represents a halogen element) is used as a carrier, and this can be realized by utilizing the burned-out luminescence seen in a fluorescent carrier obtained by adding Eu ²⁺ to the carrier. Here, the burned emission means that after the temporary emission of the fluorescent light is finished, when it is excited again by irradiating ultraviolet light or infrared light, all the stored energy becomes fluorescent and emits light again. The phenomenon that does.

If the burn-out luminescence is used, when a concrete structure is inspected for deterioration, fluorescent light is generated by irradiating an ultraviolet ray or the like. It will be easier for those who do the inspection.

Further, cracks on the surface of concrete do not necessarily occur only at the limit of the proof stress of the structure. For example, cracks may be caused by reinforcement corrosion expansion due to salt in concrete. In this case, cracks, that is, fluorescence are generated along the reinforcing bars arranged in the concrete, so that it is easy to estimate that the cause of deterioration is corrosion expansion of the reinforcing bars. Therefore, the manager of the structure can accurately judge the time to repair the concrete by using the fluorescence.

In the above embodiment, the method of pulverizing the fluorescent carrier into powder and applying the powder to the concrete surface has been described, but the present invention is not limited to this.

In another embodiment, for example, a fluorescent carrier may be prepared in the form of particles having a particle size of about 0.5 mm, mixed with cement to form a mortar, and the mortar may be applied to the concrete surface. .

Hereinafter, embodiments of the present invention will be described.

First, a powder of a fluorescent carrier was prepared as follows. That is, the raw material of the fluorescent carrier was changed to N shown in Table 1.
o. After weighing and mixing to obtain the composition of Example 1, the mixture was placed in an alumina crucible, and the alumina crucible was placed in a slightly larger alumina crucible filled with granular carbon and capped. This crucible is placed in an electric furnace, and the temperature is raised from room temperature to 1800 ° C. over 3 hours, and further kept at 1800 ° C. for 2 hours to melt the raw material, gradually cooled to 1600 ° C. over 2 hours, and then cooled to room temperature. Was allowed to cool in a furnace to obtain Sample 1. By performing powder X-ray diffraction measurement on Sample 1, it was identified as hexagonal celsian, which is one of the crystal structures of feldspar. Further, the sample 1 was pulverized with a ball mill to obtain a fluorescent carrier 1.

An embodiment in which the degradation occurring in a concrete structure is detected from the surface by applying fructoluminescence will be described below.

Example 1 <Preparation of Test Specimen> Methylsiloxane was used as a coating material, and the fluorescent carrier 1 was mixed in a ball mill at a ratio of 100 g / L. This mixture was placed in a cylindrical shape (10 cmφ × 20
cm) of the concrete specimen was applied using a brush. <Test and Results> When a compressive force was applied to the concrete specimen from above and below by a compression tester, it was observed that fluorescence was generated on the surface of the concrete specimen at the time of breaking. When the high-speed photograph was compared with the fracture surface of the concrete specimen, it was found that fluorescence was emitted in order from the position regarded as the fracture origin.

Example 2 <Preparation of Specimen> 200 g of fluorescent carrier 1 in acrylic paint
/ L. Acrylic paint mixed with the fluorescent carrier 1 was sprayed onto the lower surface of a floor-plate concrete specimen of a plate-like bridge model (100 cm × 30 cm × 3 cm) prepared in advance. <Test and Results> When the floor slab concrete specimen was loaded from above, fluorescence was generated at the center of the floor slab concrete specimen, and cracks were generated at the center of the lower surface of the concrete slab in a direction perpendicular to the longitudinal direction of the floor slab. From the analysis of the strain meter embedded in advance, the position where the fluorescence was visually confirmed coincided with the position of the crack.

Example 3 <Preparation of Specimen> In order to conduct a fructoluminescence function experiment as an index of concrete deterioration due to salt damage,
The same coating as in Example 2 was applied to one surface of a concrete plate-like specimen having a reinforcing bar. <Tests and results>
Put in a salt damage accelerating tester that sprays saturated saline intermittently,
Fluorescence was observed with salt damage. The fluorescence was observed along the rebar, but eventually cracks appeared at that location.
As a result of the inspection, it was confirmed that the reinforcing bar expanded due to rust, that is, deterioration caused by cracking of the concrete surface due to typical salt damage.

[0027]

According to the present invention, when a concrete structure reaches the limit of its proof stress, firstly, fine cracks run on the surface of the concrete which cannot withstand the tensile stress, but fluorescence is emitted from such cracks. Thereby, the crack can be easily detected as the entire surface. actually,
For example, by applying a fluorescent carrier to the underside of the bridge girder of a concrete long bridge and observing the change in color, it is possible to check the soundness of the bridge, so it is a monitoring method that replaces the conventional periodic inspection by visually observing crack patterns in detail. It is valid.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Katsuhisa Tanaka, Inventor 218, Gran-Cityo Kitayama-dori 6-2, Matsugasaki Ichimachidamachi, Sakyo-ku, Kyoto-shi (72) Inventor Koji Kataoka 4-9, Shiroyamadai, Misato-cho, Ikoma-gun, Nara Prefecture No. 13 (72) Inventor Takeo Komaki No. 99, 136 Takayama-cho, Ikoma City, Nara Prefecture F-term (reference) 2G043 AA03 CA05 DA02 EA01 GA07 GB21 KA01 KA03 LA01 2G050 AA02 BA02 BA12 CA01 CA03 DA03 EA04 EA06 EB07 EC06

Claims (2)

[Claims] 1. A fluorescent carrier generating fructoluminescence is attached to a concrete surface, and the fluorescent light emitted from the fluorescent carrier accompanying the breakage of concrete is
A method for detecting deterioration of a concrete structure, comprising detecting deterioration of the concrete. 2. A concrete structure, wherein a fluorescent carrier generating fructoluminescence is attached to a concrete surface.