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Race Street Bridge

Location: Catasauqua, Pennsylvania

Award: Infrastructure

Project Team

Owner: PennDOT Contractor: PKF Mark III, Inc.

Engineer: Pennoni

Concrete: Northeast Prestressed Products, LLC Slag Cement: Heidelberg Materials

The Race Street Bridge project in Catasauqua, PA, USA, was a lightweight bridge deck replacement on steel girders. Precast concrete was used because the Pennsylvania Department of Transportation (PennDOT) wanted to speed construction and limit disruption. The bridge was permitted to be closed for only 42 days. In addition, precast reduced any delay that weather may have impacted with a cast-in-place process.

The concrete was designed for an equilibrium weight of 115 lb/ft3 (1842 kg/m3) and reaching 5000 psi (35 MPa) in 15 hours. Lightweight sand was not permitted to be used in the mixture design. The entire project only took 56 days for completion.

The Race Street Bridge is a four-span, 386 ft (118 m) long, steel I-beam bridge originally built in 1957. The average daily traffic over the bridge is 10,691 vehicles.

Slag cement was used to ensure durability—no other supplementary cementitious material (SCM) was used in the mixture. Slag cement assisted in meeting strength gain and strength requirements for next-day form stripping. The mixture performance allowed for quick production, shipment, and placement of the final product to the jobsite. The mixture was designed to be a conventional lightweight concrete with a minimum strength of 5000 psi.

Slag cement helped with all aspects of the project, including mixture performance during placement in precast forms, excellent form finish with minimal bugholes, speed of construction on the jobsite, and overall aesthetics with form finish and color consistency.

Application Type

% Slag Cement Replacement


% Portland Cement


% Portland Limestone Cement

% Other SCM (if applicable)


950 lb Light Weight / 995 lbs FA  

Water/cement ratio


7-day strengths

7,149 psi

28-day strengths

7,266 psi  (115 lb unit weight)


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