Washington, DC
Award Category: Infrastructure
Project Team
Owner: D.C. Department of Transportation
Contractor: South Capitol Bridge Builders
Concrete: Monumental Concrete
Slag Cement: Lehigh Hanson
In this project, the use of slag cement aided with the consistency of the mix. Reaching the needed strength in an ample amount of time allowed the contractor to have an advantageous cast in-place schedule.
The engineer on record requested a low shrinkage value to help increase durability and overall strengths on the majority of delivered ready mix for the elevated slabs. This mix also included a high range water reducer and corrosion inhibitor.
SmartRock Plus maturity sensors were also used in the elevated decks to help measure in place strengths which quickened the form removal process and overall project timeline.
In this project the use of slag cement allowed a pour of slabs in excess of 1200 to 2200 cubic yards that still have curing stability/even heat distribution and contributed to the aesthetic appeal of the finished design. The bridge itself has over 15,000 cubic yards of concrete and the whole project, which includes the reconstruction of the I‐295 and Suitland Parkway interchange, totals over 40,000 cubic yards.
The top 3 mixes used in this project were 70% slag cement. They included both mass and self-consolidating concrete. In addition to the value engineering aspect, slag cement was specified in the mass mixes for curing stability, and it was specified elsewhere for the aesthetically appealing lighter color.
The New Frederick Douglass Memorial Bridge is the largest infrastructure project in DC’s history. This 1,445-foot-long structure replaced a crumbling 1950s-era functionally obsolete span and was a key step toward connecting communities on both sides. The design includes 3 above-deck arches, four pedestrian overlooks and 2 piers. It has 6 traffic lanes including the pedestrian/bicycle lanes. The project was
designed with a 100-year service life. The bridge opened to traffic on September 11, 2021.
Due to its unique design, the New Frederick Douglass Memorial Bridge will be the only bridge of its kind in the world. It is a three arch bridge supported by just two V‐piers in the river.
Application Type | Class A Modified 4500 Mass Mix |
|---|---|
% Slag Cement Replacement | 70% |
% Portland Cement | 30% |
% Portland Limestone Cement | N/A |
% Other SCM (if applicable) | N/A |
Aggregate | #57 stone |
Water/Cement Ratio | Max 0.40 |
7-Day Strengths | 4810 psi |
28-Day Strengths | 7680 psi |