UHPC Overlay Bond Strength Evaluation

The Delaware Memorial Bridge, which carries I-295 across the Delaware River between Delaware and New Jersey, is a critical transportation link for the region. As part of preservation efforts the Delaware River Bridge Authority had an ultra-high performance concrete (UHPC) deck installed on the bridge deck. To evaluate the effectiveness of the repair, BDI was engaged to determine the location and extent of delaminations and evaluate the bond strength of the new topping slab.

BDI supported the evaluation by performing non-destructive testing across approximately 24,000 square feet of bridge deck. Using BDI’s SounDAR system automated sounding of the new overlay was performed; additionally, targeted Impact Echo (IE) measurements and ASTM C1583 pull-off testing were used to evaluate material integrity and bond strength. To evaluate the progression of repair and curing, testing was performed at three intervals: 28 days, 6 months, and 12 months following repair completion.

The results demonstrated the success of the UHPC overlay repairs and validated the repair approach, with more than 99% of the tested deck area rating in good or better condition. Pull-off testing confirmed strong adhesion between the UHPC overlay and the existing concrete substrate, with failures typically occurring within the original concrete rather than at the bond interface or UHPC overlay.

The data collected by BDI provided the owner and designers with valuable insight into the effectiveness of the repair strategy, helping validate the performance of the UHPC overlay and increasing confidence in its long-term durability and service life.