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This study is intended to assess the integrity of a reinforced concrete bridge deck at the Missouri S&T campus using non-destructive testing (NDT) methods performed at top and bottom surfaces of the bridge deck. These utilized methods are named ground generating radar (GPR), impact echo (IE), and ultrasonic surface waves (USW). GPR was applied using 1.6 GHz and 2.5 GHz antennas to transmit and receive electromagnetic radio waves at embedded concrete reinforcement or distinct contacts between solid and loose concrete materials with different dielectric properties. Due to significant variations of the apparent depth to top of the embedded reinforcing steel bars, it was difficult to interpret the GPR results for the bridge deck assessment. Therefore, GPR results are often calibrated in application with ground truth data from either borehole tests or other nondestructive methods, such as IE and USW. IE and USW are based on the reflection of the acoustic waves at discontinuity (e.g., delamination). Both IE and USW data were acquired using portable seismic property analyzer (PSPA) device. USW is used to measure the variations of Young’s modulus of concrete deck and IE is used to measure depth to possible embedded defects in concrete deck. Eventually, USW and IE results were used as an indicative of the concrete quality of the bridge deck. An approximately 10 x 9 ft. sections were surveyed at the top and the bottom surfaces of the bridge deck in order to evaluate and correlate the three NDTs results for the bridge deck assessment.

DTRT06-G-0014 (Grant), Electrical Resistivity Tomography (ERT) data were acquired on the ground surface across an underground limestone mine access tunnel in an effort to characterize the roof rock. This investigation was conducted because simultaneous localized failure occurred on the ceiling of the access tunnel and elsewhere in the mine along a previously unknown northwest trending lineament. The interpretation of the ERT data indicates the limestone roof rock above the tunnel is dissected by several prominent clay-bearing near-vertical solution-widened fractures (joints or faults) that are not visually exposed on the ceiling of the tunnel. Roof rock failure in the mine access tunnel occurred at the intersection of projected northwest trending lineament and one of the more prominent solution-widened fractures identified on the ERT data.