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Proceedings Paper

Delamination detection in reinforced concrete using thermal inertia
Author(s): Nancy DelGrande; Philip F. Durbin
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Paper Abstract

We investigated the feasibility of thermal inertia mapping for bridge deck inspections. Using pulsed thermal imaging, we heat-stimulated surrogate delaminations in reinforced concrete and asphalt-concrete slabs. Using a dual-band infrared camera system, we measured thermal inertia responses of Styrofoam implants under 5 cm of asphalt, 5 cm of concrete, and 10 cm of asphalt and concrete. We compared thermal maps from solar-heated concrete and asphalt-concrete slabs with thermal inertia maps from flash-heated concrete and asphalt-concrete slabs. Thermal inertia mapping is a tool for visualizing and quantifying subsurface defects. Physically, thermal inertia is a measure of the resistance of the bridge deck to temperature change. Experimentally, it is determined from the inverse slope of the surface temperature versus the inverse square root of time. Mathematically, thermal inertia is the square root of the product of thermal conductivity, density, and heat capacity. Thermal inertia mapping distinguishes delaminated decks which have below-average thermal inertias from normal or shaded decks.

Paper Details

Date Published: 1 February 1999
PDF: 12 pages
Proc. SPIE 3587, Nondestructive Evaluation of Bridges and Highways III, (1 February 1999); doi: 10.1117/12.339924
Show Author Affiliations
Nancy DelGrande, Lawrence Livermore National Lab. (United States)
Philip F. Durbin, Lawrence Livermore National Lab. (United States)


Published in SPIE Proceedings Vol. 3587:
Nondestructive Evaluation of Bridges and Highways III
Steven B. Chase, Editor(s)

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