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Sensors 2017, 17(8), 1718; https://doi.org/10.3390/s17081718

Effects of Ambient Temperature and Relative Humidity on Subsurface Defect Detection in Concrete Structures by Active Thermal Imaging

1
Department of Civil and Environmental Engineering, Chonnam National University, Yeosu, Chonnam 59626, Korea
2
Department of Civil Engineering and Engineering Mechanics, University of Arizona, Tucson, AZ 85721, USA
*
Author to whom correspondence should be addressed.
Received: 27 June 2017 / Revised: 18 July 2017 / Accepted: 25 July 2017 / Published: 26 July 2017
(This article belongs to the Section Physical Sensors)
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Abstract

Active thermal imaging is an effective nondestructive technique in the structural health monitoring field, especially for concrete structures not exposed directly to the sun. However, the impact of meteorological factors on the testing results is considerable and should be studied in detail. In this study, the impulse thermography technique with halogen lamps heat sources is used to detect defects in concrete structural components that are not exposed directly to sunlight and not significantly affected by the wind, such as interior bridge box-girders and buildings. To consider the effect of environment, ambient temperature and relative humidity, these factors are investigated in twelve cases of testing on a concrete slab in the laboratory, to minimize the influence of wind. The results showed that the absolute contrast between the defective and sound areas becomes more apparent with an increase of ambient temperature, and it increases at a faster rate with large and shallow delaminations than small and deep delaminations. In addition, the absolute contrast of delamination near the surface might be greater under a highly humid atmosphere. This study indicated that the results obtained from the active thermography technique will be more apparent if the inspection is conducted on a day with high ambient temperature and humidity. View Full-Text
Keywords: concrete deterioration; active thermal imaging; ambient temperature; relative humidity; infrared thermography; nondestructive testing concrete deterioration; active thermal imaging; ambient temperature; relative humidity; infrared thermography; nondestructive testing
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Tran, Q.H.; Han, D.; Kang, C.; Haldar, A.; Huh, J. Effects of Ambient Temperature and Relative Humidity on Subsurface Defect Detection in Concrete Structures by Active Thermal Imaging. Sensors 2017, 17, 1718.

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