Inspection for Voids in the Grout below the Protective Duct of an External Post-Tensioning Bridge Tendon Using a THz A-Scanner

Grout voids in the tendons of a post-tensioning bridge reduce their strength. Grout voids are also severe flaws causing corrosion of the steel strands in the tendons. Detecting voids during construction and operation of the tendons is essential to prevent tendon failure, which is critical to bridge...

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Bibliographic Details
Published in:Applied sciences 2023-11, Vol.13 (22), p.12119
Main Authors: Yee, Dae-Su, Yahng, Ji Sang, Cho, Seung Hyun
Format: Article
Language:English
Subjects:
Bridges
Corrosion
Electric waves
Electromagnetic radiation
Electromagnetic waves
Electromagnetism
external tendon
Fourier transforms
Heat
High density polyethylenes
Lasers
Methods
nondestructive inspection
Nondestructive testing
post-tensioning bridge
Radiation
Radiography
Scanners
Spectrum analysis
Steel
terahertz wave
Tomography
voids in grout
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Summary:Grout voids in the tendons of a post-tensioning bridge reduce their strength. Grout voids are also severe flaws causing corrosion of the steel strands in the tendons. Detecting voids during construction and operation of the tendons is essential to prevent tendon failure, which is critical to bridge safety. This study presents a method for inspecting external tendons for voids in the grout below the protective duct pipe using terahertz electromagnetic waves. Due to low attenuation in the high-density polyethylene duct and the large reflectivity difference between the duct/grout and the duct/void interfaces, terahertz waves are suitable for detecting voids in the grout inside tendons. For this study, we developed a mobile frequency-domain terahertz A-scanner that can be used to measure terahertz A-scan data in real time. It is shown that the mobile terahertz A-scanner can be used to assess the area of the grout void in external bridge tendons.
ISSN:2076-3417
2076-3417
DOI:10.3390/app132212119