Ultra-High Performance Concrete Innovations

With over 80,000 vehicles crossing it daily, there were immense challenges to executing a major rehabilitation. The most notable challenge: the disruption to traffic and the impact it would have on the travelers and the toll collections.

The construction work could only be performed during specific timeframes when traffic volumes were relatively low. Within these tight time windows, a new durable, high performing deck needed to be installed without adding more weight to the structure.

The Delaware River and Bay Authority (DRBA) considered several options to repair or replace the existing bridge deck. After a life-cycle cost analysis, the owner determined that using
Ultra-High Performance Concrete (UHPC) was the right choice for the project.

UHPC is an exceptionally strong and durable concrete material that often includes a large amount of fiber reinforcement and super-plasticizing agents.

The UHPC would be installed as a new overlay system along the length of the bridge to protect and structurally strengthen the existing bridge deck. This solution could be installed in much less time and at a significantly reduced cost compared to more significant repair techniques (e.g., full-depth deck replacement).

Compared to a more traditional concrete overlay, a thinner layer of UHPC is needed. This minimizes additional weight to the structure and provides durability lasting 50 years or more.

In September 2023, the third and final phase of the rehabilitation project began. Crews removed 2-3 inches of deteriorated concrete from the existing deck surface of the two northbound right lanes on the New Jersey side, and then replaced it with an equivalent thickness of UHPC.

In partnership with UHPC Solutions (the general contractor) and Ductal (the UHPC material supplier), the technical team identified the best admixtures for the intended application, such as high-range water reducers.

This allows for less batch water to be used in the UHPC mixture, producing concrete that is stronger than traditional bridge deck concrete.

Additionally, the admixtures facilitated a concrete consistency that the contractor could pave in a downhill direction, which is not typically done in concrete paving. This allowed the contractor to condense their construction schedule, saving them time and money.

More than 5,000 cubic yards of UHPC was installed on this project. The UHPC was placed using a specialty paver designed by the contractor, and later it was diamond ground and grooved to ensure a smooth riding surface.

Steve Williams, Saint-Gobain Construction Chemicals North America president, said that UHPC is a key component in the sustainability goals of the construction industry because it provides greater strength with less material needed and longer service life.

“The use of UHPC on the Delaware Memorial Bridge deck rehabilitation project was the perfect fit, offering speed and light-weight durability,” Williams said.

The UHPC overlay installation shaved two weeks from the 11-week Phase 3 construction window. The enhanced performance of the new UHPC equates to less overall concrete used, which further reduces the project’s CO2 impact.

Gil Brindley, UHPC Solutions North America director, said this project was the first of its kind in the country.

“It is the first suspension bridge to have a UHPC overlay, the largest UHPC project in the U.S., and broke records for UHPC placed in a single day,” Brindley said. “The success of the project is due to the partnership of all those involved. From the owner and designer, material suppliers and subcontractors, to the workforce that performed the work, everyone played an important role and worked collaboratively to make this project a reality.” RB

Lisa Barnard, LEED AP, WELL AP, is CHRYSO & GCP’s sustainability and customer engagement program manager.