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Bridge Preservation Efforts NCDOT wants to replace the structure, but a replacement is on hold due to lawsuits. In the interim, NCDOT started repair work to keep this essential connection to the barrier island open. To date, Coastal Gunite Construction Company has performed three separate concrete rehabilitation projects on the structure. The first rehabilitation project began in 1987, nearly 25 years after the bridge first opened. Coastal Gunite repaired spalled concrete and damaged reinforcing steel on the bridge bents— everything from the support bearings to the waterline, including bent caps, columns, and footers (Fig. 2). The project took 2 years, and all distressed concrete was identified, removed, and replaced. The shotcrete mixture used for the repair was a Fig. 2: Chipping of unsound concrete simple 3:1 sand-cement mixture that was batched on-site by the contractor. “We thought that would be our one and only rehab on the Bonner Bridge. We repaired every- thing on the substructure and figured they’d build a replacement before anyone had to do more concrete repair,” said Curt White, President and Founder of Coastal Gunite Construction Com- pany. “Well, 20 years later, there was no replace- ment and we were contracted to perform more repairs,” he continued. In 2008 and 2009, Coastal Gunite repaired spalled concrete and damaged reinforcing steel on the bridge bents. In addition, the underside of the superstructure was repaired, including the concrete beams and the underdeck. Interestingly, all the repair work done in this phase was on concrete NOT repaired 20 years earlier. All of the earlier concrete repairs were still in sound condi- tion (Fig. 3). Then, in 2013 and 2014, Coastal Gunite performed a third round of repairs on the bent caps and underdeck. This repair addressed new areas that were not previously identified for repairs. Both the second and third repair itera- tions were performed with a prepackaged shot- crete mixture enhanced with silica fume and polypropylene fibers. Tim Ayers, Coastal Gunite Project Superin- tendent, oversaw the concrete rehabilitation in both 2008 to 2009 and 2013 to 2014. During Fig. 3: Unsound concrete removed these projects, he became intimately familiar with the structure and its past repairs. As a testa- ment to the durability of shotcrete in marine conditions, Ayers maintains that all previous Interesting Fact shotcrete repair work has remained intact and all Oregon Inlet was formed when a hurricane lashed the Outer Banks repair work in return visits consisted of newly in 1846, separating Bodie Island from Pea Island. Similar to other identified damage to the original concrete. inlets along the Outer Banks, Oregon Inlet moves southward due to “We’ve gone back to spots on the bridge and drifting sands during tides and storms. It has moved south over 2 miles saw shotcrete patches that were placed 20-plus since 1846, averaging around 66 ft (20 m) per year. years ago,” said Ayers. “And you know what? Shotcrete • Summer 2014 21


2014SumShotcreteEMag
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