United States Department of Transportation
i
Fast Reference-free Crack Measurement (RACM) System in Transportation Infrastructures using Non-Contact Ultrasound
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2018-08-01
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By Ham, Suyun
[PDF-7.05 MB]
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Abstract:According to a 2017 report by the American Society of Civil Engineers, the infrastructure of the United States requires a $2.0 trillion investment to return it to good condition by 2025. Distributed microcracks and delaminated damages in our transportation system’s concrete infrastructure have caused more deterioration by cracks and more delamination by corrosion, adversely affecting the system components’ mechanical strength, stiffness, and permeability. Freeze and Thaw (F&T) and Alkali Silica Reaction (ASR) are the most common cause of the microcrack formation in the concrete infrastructures. The early detection of these propagating damages through a pragmatic non-destructive testing (NDT) technique can lead to a better decision making which prevents further degradation and saves money, time, and lives. As of today, there is no NDT method that has proven to be sensitive to the early stage damages such as F&T in an inhomogeneous infrastructure. The methods are either insensitive to early stages (low crack volumes) of damage, not repeatable, or inconsistent. Prior methods have had an inadequate contact system that cannot measure the damage quickly enough as they require a contact to the surface, and a more sophisticated reference data system that can more readily respond to the nature of the heterogeneous aspects of the problem sites. This research presents the solution in the form of a reference-free acoustic crack measurement (RACM) system. The developed RACM system provides absolute damage index values. The RACM utilizes non-contact ultrasonic system to implement backscattering waves to characterize the damage level. Three F&T damaged specimens were prepared and tested with the RACM and other techniques such as resonant frequency tests and expansion tests in a laboratory. The research presents the results of the field tests using the ultrasonic sensor array device (MIRA) and RACM system. In addition, website-based and App-based monitoring platforms are developed to allow fast access to the test results using map-based location displayer.
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