(For Both Lightweight Geotechnical Fill and Structural Lightweight Concrete)
by Michael Robinson, Carolina Stalite Company
Owner: District Department of Transportation
Designer: Johnson, Mirmiran, & Thompson
Contractor: Skanska-Facchina, J/V
ESCS Supplier: Carolina Stalite Company
Skanska-Facchina, J/V was awarded a $390 million design-build contract to reconstruct the 11th Street bridges and interchanges in Washington, DC. Phase 1 includes three new bridges that will replace two bridges built in the 1960’s. Phase 2 further improves connections to the Southeast-Southwest Freeway with the new 11th Street Freeway Bridge. Construction began in December 2009 and is scheduled for completion in late 2015.
For decades, no direct connection existed between the Southeast Freeway (I-695) and the northern segment of the Anacostia Freeway (DC 295/I-295), causing commuter traffic to use local streets in the Anacostia and Capital Hill neighborhoods. The 11th Street Corridor project will separate local traffic from commuter traffic and will complete freeway connections between the Southeast and Anacostia Freeways while providing economic stimulus to the area.
Lightweight aggregate was selected by the design-build team to play an important role in the completion of this project. Over 18,000 tons of Stalite lightweight aggregate was used in the phase 1 construction of the 11th Street Corridor Project. Stalite representatives visited the project and met with Scott Randall, Skanska project manager, to find out how lightweight aggregate was employed on the project. He explained that a large (about 11,500 tons) amount of lightweight aggregate was used as lightweight fill on the project. Storm sewer outflow structures constructed in the late 1800’s and still in use today had to be preserved to maintain drainage within the project area. Lightweight aggregate fill was used to produce a “net zero” load when the grade was raised over them during the construction of the new bridges. Lightweight aggregate fill was also used in the construction of portions of the MSE walls on the project.
The balance of the lightweight aggregate was used in the production of lightweight concrete for the bridge deck of the bridge which will be used for local traffic and includes a shared use path for pedestrians and bicyclists.