Excessive Pile Breakage, Gaylord National Resort and Conference Center, a Look Back 15 Years Later-Paper

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The Gaylord National Resort and Convention Center in Maryland was founded on about 150,000 linear feet of driven precast concrete piles. During production driving in 2005, roughly 100 of approximately 2,000 piles were damaged; about 85 required replacement. Concerns initially focused on driving criteria, hammer size, and challenging ground conditions, including an abrupt transition between alluvial deposits and the Potomac Formation.<br /><br />A forensic investigation identified pile concrete as the principal cause. Core tests from three damaged production piles found that many samples had compressive strengths below the specified 6,000 psi, even when tested 39–52 days after casting. The piles had been driven only 21–28 days after casting, when their strength was likely lower. Petrographic testing found substantial NewCem slag cement in the production piles. By contrast, a test pile made with 100% Portland cement had performed well. The original specification required 6,000 psi at 28 days but did not require that strength at the time of driving or prohibit cement substitutes. The driving hammer was not considered a major contributor.<br /><br />Adjacent National Harbor projects continued to use precast piles after specifications were changed to require 100% Portland cement and 6,000 psi strength by seven days. Those projects experienced far fewer pile breakages, supporting the conclusion that inadequate early concrete strength was central to Gaylord’s problems.<br /><br />The case demonstrates that pile strength during installation—not merely at the conventional 28-day benchmark—is critical. The author recommends specifying early-age strength, considering Portland-cement-only mixes, testing trial batches independently, and using independent laboratory quality assurance.

Keywords

Gaylord National Resort

concrete piles

precast piles

pile damage

forensic investigation

compressive strength

NewCem slag cement

Portland cement

early-age strength

quality assurance