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ANOTHER LOOKS: APPLICATION OF STICK SCANNERIN RC STRUCTURES ASSESSMENT
Achfas ZACOEB, Yukihiro ITO, and Koji ISHIBASHI
The 3rd International Conference of European Asian Civil Engineering Forum (EACEF)
Yogyakarta, 20 22 September 2011
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BackgroundConcrete
StructuresDefect and
Deterioration
Structure soundness
assessment
To extent a service time by structure
strengthening or repairingElapsed time and
various reasons
To identify the basic
causes of damage or defect
One of the remedial measures
is Visual Inspection*
* For assessing the inside defect and deterioration in concrete structure requires a special device
such as borescope. Small diameter of core drilled is preferred to minimize the damage for giving
a concrete restoration from structure inspection activities by partial destructive test.
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Objectives To get a plural information and better understanding of
damage from internal image of concrete structure that
capturing by the development device of SS from one
inspection borehole. To give an outlook of field application by using the
developed inspection method in existing concrete
structures.
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Outline of Device
The 1st SS The 2nd SS
The 3rd SS
The specifications of SS model
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Detail of PartsOutline of Device
(contd)
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PerformanceCalibration of image size
The accuracy of image reading representation is
examined by inserting a 1mm grid sheet to the inside of
aluminum stiff pipe with the same internal diameter as aninspection drilled hole (24.5mm).
The distance of each point of a rotation and
insertion direction was confirmed from the
representation image, whereas the accuracy was
compared with an actual measurement.
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Performance (contd)
The acquisition of scanning image
Image size measurement error
This error is possible caused by thedifferences of diameter between the
guide rings that had been used for
rotating the sensor with the inspection
drilled hole, but this error does not
pose any problem in practice and still
in the tolerance level (< 5%).
0.084mm for 1st
SS (300dpi)
0.042mm for 2nd and 3rd SS (600dpi)
1 pixel
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Verification by crack width measurement
Verification is conducted in order to meet the
requirements of accuracy and reliability. Accuracy of
crack width measurement is examined by cutting a
cylinder specimen with an inspection drilled hole into
two equal parts
For artificial crack is created by inserting a separator
plate between two test specimens and supporting in
fixed position. The crack widths that had been
analyzed were 0.05, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0,1.5, 2.0, 3.0, 4.0, and 5.0mm.
The calculation method of crack width was confirmed
by calculating a number of the counted pixels of
cracking part and multiplying by 0.42 (1 pixel =
0.42mm) from the representation image
Performance (contd)
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The crack width measurement is calculated from three times
observation in three different parts of crack in the same
image for each actual value. The result of crack width
measurement is shown in table with absolute total meanerror of 2.63% and still in tolerance level less than 5%.
Actual crack width VS Experimental value
Performance (contd)
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Image pixel always becomes the same
size with scanner reading resolution.
This image is enabled to confirm fine
aggregate or cracking condition biggerthan 0.05mm.
No need a scale calibration in copying
process.
Arbitrary distance between two points in
an image can be easily measured from the
calculation of the pixels number.This device can perform accumulation
display of image as well as pixel size
being constant precisely because there is
no image distortion.
This digital image is also enabled to
conduct a various analyses.
Common Part of Both Images
Surface
side
Surface
side
Method of Image CompositionSurface
side
Method of ImageExtraction
Characteristic of Capturing Image
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Supporting Tools and Devices
Air blower
Rotary hammer machine
Hammer drill bit
dof 13mmGuide stick
Diamond drill bit
Dust emission brusherEmery paper polisher
Core drilled machine
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Inspection Procedure
The SS is enabled for capturing image of inside borehole up to 1000mm in depth by
installing the extension pipe and inserting the sensor part deeper to scan another image.
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Outlook of Field Application
The Elevated Roadway in Dazaifu, Fukuoka
as research object for
application of the 2nd SS
The Elevated Railway in Karatsu, Saga
as research object for
application of the 1st SS
Inside Deterioration Assessment
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Inspection mark
Rebar arrangement mark
Location Marking
Hammer Drilling Inspection borehole Image Capturing
Sample of final analysis image
Outlook of Field Application (contd)Inside Deterioration Assessment
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Interfacial Debonding Monitoring
The S Bridge in Kashii, Fukuoka
Outlook of Field Application (contd)
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Reference image of initial stage
Improper
captured
image
Outlook of Field Application (contd)Interfacial Debonding Monitoring
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Concluding Remarks SS that named as developed device is available to capture an inside image
up to 1000mm in depth by installing the extension pipe and the capturing
image is analyze in PC by using the composition method. Accuracy of
measurement by using this device is highly with mean error of absolutevalue of all the tolerances is 2.63%. Measurement with this device, 1 pixel
becomes 0.084 and 0.042mm for resolution 300 and 600dpi, respectively.
By using a small inspection borehole diameter of 24.5mm, it will faster for
segment restoration and no giving any significant effect towards structure
performance. Inside inspection of concrete structure that conducted by thisdevice is effective to obtain plural information from one inspection mark such
as crack, void, carbonation, chloride content, etc. The image that captured is
reliable for analysis the condition of inside defect in concrete structures to
determine the grade of appearance.
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