A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Using emissivity-corrected thermal maps to locate deep structural defects in concrete bridge decks
Dual-band infrared (DBIR) thermal imaging is a promising, non-contact, nondestructive evaluation tool to evaluate the amount of deteriorated concrete on asphalt-covered bridge decks. We conducted proof-of-principle demonstrations to characterize defects in concrete structures which could be detected with DBIR thermal imaging. We constructed two identical concrete slabs with synthetic delaminations, e.g., 1/8-in. thick styrofoam squares, implanted just above the 2-in.-deep steel reinforcement bars. We covered one of the slabs with a 2-in. layer of asphalt. We mounted the DBIR cameras on a tower platform, to simulate the optics needed to conduct bridge-deck inspections from a moving vehicle. We detected 4-in. implants embedded in concrete and 9-in. implants embedded in asphalt-covered concrete. The midday (above-ambient) and predawn (below-ambient) delamination-site temperatures correlated with the implant sizes. Using DBIR image ratios, we enhanced thermal-contrast and removed emissivity-noise, e.g., from concrete compositional variations and clutter. Using the LLNL/VIEW code, we removed the asphalt thermal-gradient mask, to depict the 4-in. deep, 9-in. square, concrete implant size. We plan to image bridge deck defects, from a moving vehicle, for accurate estimations of the amount of deteriorated concrete impairing the deck integrity. Potential longterm benefits are affordable and reliable rehabilitation for asphalt-covered decks.
Using emissivity-corrected thermal maps to locate deep structural defects in concrete bridge decks
Dual-band infrared (DBIR) thermal imaging is a promising, non-contact, nondestructive evaluation tool to evaluate the amount of deteriorated concrete on asphalt-covered bridge decks. We conducted proof-of-principle demonstrations to characterize defects in concrete structures which could be detected with DBIR thermal imaging. We constructed two identical concrete slabs with synthetic delaminations, e.g., 1/8-in. thick styrofoam squares, implanted just above the 2-in.-deep steel reinforcement bars. We covered one of the slabs with a 2-in. layer of asphalt. We mounted the DBIR cameras on a tower platform, to simulate the optics needed to conduct bridge-deck inspections from a moving vehicle. We detected 4-in. implants embedded in concrete and 9-in. implants embedded in asphalt-covered concrete. The midday (above-ambient) and predawn (below-ambient) delamination-site temperatures correlated with the implant sizes. Using DBIR image ratios, we enhanced thermal-contrast and removed emissivity-noise, e.g., from concrete compositional variations and clutter. Using the LLNL/VIEW code, we removed the asphalt thermal-gradient mask, to depict the 4-in. deep, 9-in. square, concrete implant size. We plan to image bridge deck defects, from a moving vehicle, for accurate estimations of the amount of deteriorated concrete impairing the deck integrity. Potential longterm benefits are affordable and reliable rehabilitation for asphalt-covered decks.
Using emissivity-corrected thermal maps to locate deep structural defects in concrete bridge decks
N. K. Del Grande (author) / P. F. Durbin (author)
1995
15 pages
Report
No indication
English
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