Nondestructive testing of reinforced concrete bridges using radar imaging techniques (original) (raw)

2002, Final Research Report …

Electromagnetic wave interactions with a concrete bridge deck. 8.2 Geometry of incident, reflected and transmitted waves interacting with two different media. 8.3 Multi-layered bridge deck model with reinforcing bar layer (Halabe et al., 1995b) 8.4 2-D geometry of moving antenna and hyperbolic nonlinear distortion. 8.5 Hyperbolic nonlinearity that results from moving an antenna relative to a fixed reflector at various depths. (Reflector cross-range x r = 0) 8.6 B-scan of an aluminum bar in air over a piece of Echosorb™. 8.7 Lattice unit cell in Cartesian coordinates (Taflove, 1988). 8.8 The PML technique (Berenger, 1994). 8.9 Relative sizes of a 1 GHz bow-tie antenna (left) and a 1 GHz TEM horn antenna (Smith, 1995). 9.1 Waveform generated for a sound bridge deck. 9.2 Waveform generated for a 1mm water-filled delamination. 9.3 Waveform generated for a 1mm 50% water-filled delamination 9.4 Waveform generated for a 1mm air-filled delamination. 9.5a Unfiltered intensity plot for air-filled delamination. 9.5b Intensity plot for air-filled delamination using average waveform filter. 9.5c Intensity plot for air-filled delamination using first waveform filter. 9.6a Unfiltered intensity plot for water-filled delamination. 9.6b Intensity plot for water-filled delamination using average waveform filter. 9.6c Intensity plot for water-filled delamination using first waveform filter. 9.7a Unfiltered intensity plot for 50% water-filled delamination. 9.7b Intensity plot for 50% water-filled delamination using average waveform filter. 9.7c Intensity plot for 50% water-filled delamination using first waveform filter. 9.8 Waveform generated for a 1 mm air-filled delamination, antenna height =102 mm (4in). 9.9 Waveform generated for a 1 mm air-filled delamination. (antenna height =305 mm =12in). 9.10a Unfiltered intensity plot for air-filled delamination, antenna height = 102 mm (4"). 9.10b Intensity plot for air-filled delamination using average waveform filter, antenna height = 102 mm (4"). 9.10c Intensity plot for air-filled delamination using first waveform filter, antenna height = 102 mm (4"). 9.11a Unfiltered intensity plot for air-filled delamination, antenna height = 305 mm (12"). 9.11b Intensity plot for air-filled delamination using average waveform filter, antenna height = 305 mm (12"). 9.11c Intensity plot for air-filled delamination using first waveform filter, antenna height = 305 mm (12") 9.12a Sketch of simulation space for 2-dimensional FDTD model with relative transmitter/receiver locations for simulations 1, 3, and 5. 9.12b Relative transmitter/receiver locations for simulations 2, 4, 6. 9.13 Relative reflected energy as a function of antenna separation for a water-filled delamination. 9.14 Relative reflected energy as a function of antenna separation for an air-filled delamination. 9.15 Sketch of distances radar wave must travel for different antenna separations. (a) D 1 ≠ D 2 (b) D 1 = D 2. 9.16 2-dimensional finite difference simulation plots of the reflected waveform from a sound bridge deck at different transmitter/receiver separation distances. (a)colocated (b) separation distance = 65 mm (c) separation distance = 260 mm. 9.17 Simulated reflected waveforms at a transmitter/receiver separation distance of 260 mm (a) sound deck (b) deck with air-filled delamination (c) deck with water-filled delamination. 9.18 Scattering amplitude spectra for antenna height of 152 mm and a transmitter/receiver separation of 260 mm (a) air-filled delamination (b) waterfilled delamination. 10.1 Correlation of GPR to cores measurement of rebar depth based on Wyoming Transportation Department study. 10.2 Image of rebars and defects inside of a concrete slab by Mast and Johansson (1994a). 10.3 Flowchart of synthetic aperture algorithm (Soumekh, 1999). 10.4 Geometry of wavenumbers associated with the synthetic aperture imaging hyperbolic nonlinearity. 11.1 Details of impedance-matching low-loss antenna apex connection. 11.2 Schematic of horn antenna. 11.3 Photo of horn antenna before mounting and encasement. 11.4 Picture of cart with GPR system. 11.5 Schematic of information flow in UVM GPR system. 12.1 Diagram of NIST design TEM horn antenna. 12.2 Diagram of parallel plate extensions with resistive loading used with the NIST design TEM horn antenna. 12.3 Diagram of Sandia design for TEM horn antenna (Aurand, 1996). 12.4. Schematic of GIMA horn antenna design. 12.5 Reflected signal versus time for one 90mm slab using GIMA-6 antenna and the HP8753D. The negative envelope denotes the front of the slab, while the positive envelope corresponds to the rear of the slab. 12.6. Reflected signal versus time for two 90mm slabs stacked with a 1mm gap using GIMA-6 antenna and the HP8753D. A signal from the 1mm gap is apparent. 12.7. Reflected signal versus time for two 90mm slabs stacked with a 50mm gap using the GIMA-6 antenna and the HP8753D. Signals from both surfaces of the gap are apparent. 12.8. Reflected signal versus time for two 38mm slabs stacked with a 1mm gap using the GIMA-1 antenna and the Sandia National Labs 1-16 GHz impulse GPR system. Both surfaces of the gap are apparent. soaked in tap water. Slab 3 was soaked in salt water. 13.1 Field test conducted at the Waterbury bridge, before new concrete deck is placed. 13.2 Bostwick Bridge, Shelburne, VT deck section. 13.3 Second Bostwick Bridge, Shelburne, VT deck survey. 13.4. GPR waterfall plot of the results obtained over a relatively good condition portion of the deck of the Bostwick Bridge, Shelburne, VT. 13.5.1 GPR waterfall plot of the results obtained over an asphalt-filled patch of the deck of the Bostwick Bridge, Shelburne, VT. 13.6 GPR waterfall plot of the results obtained over several small asphalt-filled patches on the deck of Bostwick Bridge, Shelburne, VT. 13.7 Direction and path of the long scan on the Bostwick Bridge, Shelburne, VT. 13.8 Measured grid over a small deck area with spalling and repaired patches on Bostwick Bridge, Shelburne, VT. 13.9 Results of the Scan 2 over the measured grid on Bostwick Bridge, Shelburne, VT. Correlation with subsurface structures are noted. 13.10. Photo of Turkey Lane bridge with GPR cart in the background. 13.11. Side shot of the Turkey Lane bridge. 13.12 Scanning the Turkey Lane bridge deck.