The Albemarle Sound Bridge is located on North Carolina State Highway 32 between US 64 and Edenton. Constructed in 1991, the overall length of the bridge is 18,460 ft and is comprised of three sections: 8,290 ft of south trestle spans, 6,015 ft of north trestle spans, and 4,015 ft of approach and main span units connecting the north and south trestle spans.

The scope of this project included the evaluation of the 4,015-ft-long approach and main spans for a total of 31 spans. The superstructure is comprised of precast segmental post-tensioned box girders. The bridge was identified by the NCDOT for corrosion evaluation of its external and internal post-tensioned tendons.

The evaluation process included a series of steps starting with review of available structural drawings of the bridge. A series of non-destructive tests in conjunction with limited destructive testing served as the backbone for this evaluation process. For internal tendons that are fully embedded in the concrete, Ground Penetrating Radar (GPR) with a high frequency antenna was utilized to identify the actual tendon profiles inside the top slab. The internal tendons were located on pier and other segments in a banded fashion. Sounding (tapping) of the external post-tensioning ducts were conducted end to end over their exposed length to determine the presence of voids inside the duct. Visual evaluation was conducted alongside to detect signs of corrosion. Evaluation of select anchorages and the high points of the tendon profile were also included. Deterioration associated primarily with corrosion and/or other related factors if any, were documented.

Based on the analysis of test data, the remaining service life of the concrete deck was evaluated. As a part of this evaluation, appropriate repair strategies to address corrosion condition of the post-tensioned tendons were recommended for further considerations.

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https://www.wspgroup.com/en/WSP-USA/What-we-do-USA/Projects/Albemarle-Sound-Bridge/