JPH05203596A - Management of concrete structure - Google Patents

Abstract

PURPOSE:To grasp a placing state and the like of concrete in a mold-mounted condition from the outside by detecting infrared radiation emitted from a mold and the concrete and indicating an image of the change of a difference between both temperature. CONSTITUTION:Concrete 5 is placed into a metal form mold 1, at this time the outer face of a metal form is photographed by the use of an infrared radiation camera 2 and with an image processed within an image processing part 3 the temperature distribution of the concrete 5 is shown on CRT 4. In addition, in order to observe a placing condition by means of a visible image, a transparent acrylic plate 6 is fitted to the reverse side of the mold 1 to photograph it by the use of a videocamera 7. Thereby, for instance, the part of a void for simulating a defect is shown at a lower temperature than the part of the other concrete 5 and the position and size of the void can be detected from the outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique effectively applied to concrete injection control during construction of a concrete structure and defect detection after construction.

[0002]

2. Description of the Related Art In concrete structures such as buildings,
When voids or junkers are formed inside the concrete, not only the strength is deteriorated, but also corrosion and the like due to the intrusion of water are accelerated, and durability is remarkably shortened.

Therefore, it has been important to inspect the internal condition of the concrete at the time of pouring the concrete and to detect defects inside the concrete after the concrete is poured.

In order to diagnose the durability of a concrete structure, it is important to know how the actual reinforcement is done inside the concrete.

[0005]

By the way, in building construction and the like, the control of concrete driving, that is, whether or not concrete is evenly filled in the formwork, and whether or not voids are generated, are inspected. Visual inspection was performed, and defects such as voids and junkers due to poor compaction could only be detected after the mold was demolded.

[0006] For steel shell caisson, buried frame, etc.,
Since the mold itself was not removed, it was not possible to confirm the presence or absence of defects such as voids and junkers even after the concrete was hardened.

Further, the internal rebar condition cannot be detected without actually performing a process such as cutting out a part of the concrete, which makes it practically difficult to inspect the inside of the concrete.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique capable of externally ascertaining a concrete driving condition and a reinforcing bar condition with a mold mounted. It is in.

[0009]

According to the present invention, in a concrete structure in which concrete is filled in a formwork, infrared rays radiated from the formwork and concrete are detected,
The first gist of the present invention is to display the change in temperature difference between the formwork and concrete as an image and inspect the filling state inside the concrete.

Further, in the concrete structure in which the reinforcing bars are arranged, the reinforcing bars are heated, and the heat distribution image obtained from the infrared rays radiated from the concrete surface is measured to detect the internal reinforcing condition. This is the second gist.

[0011]

The principle of the present invention will be described below.

That is, an object having an absolute temperature of zero degrees or more emits infrared rays having an intensity corresponding to the temperature, and the temperature TK
The energy amount of infrared rays (electromagnetic waves) per unit wavelength emitted from the object is expressed by the following formula. Wλ (λT) = C ₁ λ ⁻⁵ [exp (C ₂ / λ · T) −1] ^{−1 The} total energy amount is W (T) = σ · T ⁴ ( σ: Boltzmann constant)

On the other hand, the wavelength λm at which radiation is maximum at a certain temperature T is λm (T) = 2898 / T (unit: μm), and the total energy amount is proportional to the fourth power of the absolute temperature, and the radiant energy is The maximum wavelength becomes longer as the temperature becomes lower.

Therefore, it is known that the temperature difference can be measured by converting this wavelength (infrared ray) into an electric signal.

The present invention is an application of the above-mentioned principle, and an improvement is made corresponding to a special purpose of managing concrete structures.

That is, it is generally known that the temperature of the concrete formwork is substantially equal to the outside air temperature, and the temperature of the concrete itself is about 15% higher than the outside air temperature. Therefore, when concrete is driven into the formwork, the temperature of the formwork in contact with the concrete rises.
By subjecting such a temporal change in the temperature difference to heat distribution image processing, it is possible to detect the uplifting condition and the flowing condition of the concrete.

By heating the reinforcing bar inside the concrete, the temperature of the reinforcing bar and the concrete around the reinforcing bar rises. By detecting the infrared rays emitted from the surface of the concrete due to this temperature rise and imaging the heat distribution, it is possible to accurately recognize the reinforcement arrangement inside the concrete.

[0018]

Example 1 In this example, concrete 5 is driven into a mold 1 as shown in the following experimental example, and a change in temperature difference between the mold 1 and the concrete 5 is recognized as a heat distribution image by infrared rays. did.

(Experimental Example) As shown in FIG. 1, concrete 5 is cast into a metal foam mold 1 (height 60 cm, width 45 cm, depth 10 cm), and the outer surface of the metal foam at this time is photographed by an infrared camera 2. The temperature distribution of the concrete 5 was displayed by image-processing this by the image-processing part 3 and outputting it to CRT4.

Further, in order to see the driving condition as a visible image, a transparent acrylic plate 6 was fitted on the opposite side of the metal foam mold 1 and a video camera 7 was used for photographing.

The infrared camera 2 used here is of an electronic cooling type having a detection wavelength band of 3 to 5 μm and an instantaneous visual field of 2 mrad.

As shown in FIG. 2 (a), the experimental model shown in FIG. 1 was equipped with a vinyl chloride pipe 8 having a diameter of 20 cm, simulating the voids 10, on the assumption of a defect caused when concrete is poured. Also, as shown in FIG. 2 (b), the height is 20c.
A model simulating the m bean board 11 was also prepared. As the concrete 5, the water-separable concrete 5 having a slump flow of about 60 cm was used in the model of FIG. 1 (a), and the ordinary concrete 5 having a slump flow of about 18 cm was used in the model of FIG. 1 (b). The bean board 11 has the same temperature as the temperature of the concrete 5,
Concrete 5 was wet-screened with a 5 mm screen to produce coarse aggregate, which was placed in the mold 1.

FIG. 3 is a heat distribution image of the model having the void 10 shown in FIG. At this time, the temperature of the metal foam mold 1 is 9.0 ° C., the temperature of the concrete 5 is 19.5 ° C.,
Measurement of heat distribution image, temperature step 0.6 ℃, color 1
Six colors were used.

As a result, it was revealed that the portion of the void 10 simulating the defect is displayed at a lower temperature than the other portions of the concrete 5, and the position and size of the void 10 can be detected from the outside. ..

FIG. 4 is a heat distribution image of a measurement result immediately after the concrete driving in the model in which the miniature board 11 shown in FIG. 1 (b) is arranged. At this time, the temperature of the metal foam mold 1 was 16 ° C., the temperature of the concrete 5 was 21 ° C., and the heat distribution image was displayed with a temperature step of 0.3 ° C. and 16 colors. As a result, the temperature of the mini-board 11 is lower than that of the concrete 5,
Its size was also almost the same as that of the bean board 11 installed therein. The temperature of the mini-board 11 is low because the coarse aggregate is in point contact with the mold surface, and the average temperature as a whole is lower than that of the concrete 5 contacting the mold 1 as a fluid. It is thought that this is because it becomes lower.

FIG. 5 shows the relationship between the launch height of the concrete 5 and the height of the concrete 5 detected by the heat distribution image in the model simulating the void 10 in FIG. 1 (a). As shown in the figure, the heat distribution image is detected to be smaller than the actual launch height by about 0.5 to 4 cm. It is considered that this is due to the time required for the temperature of the concrete 5 to be transmitted to the outer surface of the mold 1. However, practically, it can be said that the launch status of the concrete 5 can be detected almost in real time.

FIG. 6 shows the results obtained by unsteady heat conduction analysis as to how the temperature of the concrete 5 cast into the formwork 1 is transferred to the outer surface of the formwork 1.

The numerical values used for the analysis are as follows. The thickness of the metal foam formwork 1: 2 mm Thermal conductivity: 1.92Kcal / mm · s · ℃ specific heat × ^{density: 8.243 × 10 -7 Kcal / mm} 3 · ℃ heat transfer coefficient: 2.789 × 10 ^{- 9} Kcal / mm ・ s ・ ℃ As shown in the figure, the temperature difference between the mold 1 and the mold 1 is large immediately after the concrete is poured, and the temperature of the mold 1 approaches the temperature of the concrete 5 with the passage of time. If the portion where the concrete 5 is not in contact is regarded as the void 10, it can be seen that even a small void 10 can be easily detected immediately after the concrete is poured. However, considering that there is a temperature difference between the formwork 1 and the concrete 5 even after a certain amount of time, it is possible to appropriately select the resolution, the measurement distance, etc. of the infrared camera 2 to be used. It is also possible to detect a smaller void 10.

[0029]

[Embodiment 2] FIG. 7 shows an inspection method in this embodiment. The vicinity of both ends of the reinforcing bar 12 arranged in the concrete structure is exposed to the outside, and a predetermined voltage is applied to both ends. The reinforcing bar 12 generates heat due to electric resistance, and the temperature around the reinforcing bar 12 rises. At this time, the reinforcing bars are provided on the inner side of about 3 to 5 cm from the surface of the concrete 5, and the temperature of the concrete surface corresponding to the reinforcing bar portion becomes higher than the temperature of the other surrounding concrete surfaces.

Infrared rays radiated by the temperature rise of the concrete surface are photographed by the infrared camera 2, which is image-processed by the image processing unit 3 and displayed on the CRT 4 as a heat distribution image as in the first embodiment.

At this time, by appropriately adjusting the amount of electric power applied to the reinforcing bar 12, it becomes possible to clearly detect the condition of the reinforcing bar by the heat distribution image. As a result, it is possible to easily grasp the reinforcing bar arrangement from the outside, it is possible to predict the durability of the concrete structure in advance, and it is possible to quickly take measures such as reinforcement.

In this embodiment, the method of heating the reinforcing bar 12 has been described in the case of conducting electricity. However, heating means such as a heater may be provided at the end of the reinforcing bar 12 to directly heat the reinforcing bar itself. ..

[0033]

As described above, according to the present invention, it is possible to grasp the concrete driving condition and the reinforcing bar condition of a concrete structure from the outside in a state where the formwork is mounted.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an experimental example in Example 1 of the present invention.

2 (a) and 2 (b) are front views showing a model in Example 1. FIG.

FIG. 3 is an explanatory view showing a heat distribution image in an experimental example of Example 1.

FIG. 4 is an explanatory diagram showing a heat distribution image in an experimental example of Example 1.

FIG. 5 is a graph showing the relationship between the actual launch height of concrete and the detected concrete height in Example 1.

FIG. 6 is a graph showing the result of heat conduction analysis in the mold in Example 1.

FIG. 7 is an explanatory diagram showing an inspection method in the second embodiment.

[Explanation of symbols]

 1 ・ ・ Form 2 ・ ・ Infrared camera 3 ・ ・ Image processing unit 4 ・ ・ CRT 5 ・ ・ Concrete 6 ・ ・ Transparent acrylic plate 7 ・ ・ Video camera 8 ・ ・ Vinyl chloride pipe 10 ・ ・ Gap 11

Claims (3)

[Claims] 1. In a concrete structure in which a formwork is filled with concrete, infrared rays radiated from the formwork and the concrete are detected, and a change in temperature difference between the formwork and the concrete is displayed as an image to display the concrete. A method for managing a concrete structure, characterized by inspecting a filling state inside. 2. In a concrete structure in which reinforcing bars are arranged inside, the reinforcing bars are heated and at the same time, a heat distribution image obtained from infrared rays radiated from the concrete surface is measured to detect an internal reinforcing state. A method for managing a concrete structure, which is characterized in that 3. The method for managing a concrete structure according to claim 2, wherein the heating of the reinforcing bar is performed by the heat generated by the electric resistance of the reinforcing bar when electricity is applied to the reinforcing bar.