Peace Bridge

Slag Cement: St. Marys Cement

Award:  High Performance

The Peace Bridge, located in Buffalo, NY, is the second busiest border crossing between the United States and Canada. It measures 3580 ft (1090 m) in length and includes three traffic lanes and two pedestrian sidewalks on each side. The center lane of this three-lane bridge is reversible, allowing for two-lane operation in one direction during peak hours.

A 40% slag cement mixture was used to help meet a list of performance testing requirements for the project including but not limited to chloride permeability resistance, alkali silica-reactivity (ASR), and compressive strength. Testing for permeability showed less than 1000 coulombs at 28 days and average linear shrinkage of 0.046%. The concrete mixture had a water-cementitious materials ratio  of 0.37 with a 28-day compressive strength of 7570 psi (52 MPa). ASTM C1567 for ASR mitigation of the aggregates showed that 40% slag cement was enough to mitigate the potential for ASR potential.  

Originally the project did not allow the use of slag cement and required fly ash to be used. Based on the duration of the project, the ready mix supplier’s lower capacity for ash, and the extensive testing needed, acquiring fly ash from a single source would have been difficult, leading the team to use slag cement instead.

Some notable aspects of this project include the structural steel replacement, rehabilitation and strengthening, and the installation of electrical and fiber infrastructure as well as new architectural traffic control gantries, railings, and light posts.

Note: 1 psi = 0.007 MPa

Project Team

• Owner: Buffalo and Fort Erie Public Bridge Authority
• Contractor: LiRo Engineers, Inc.
• Architect: American Bridge
• Engineer: Parsons
• U.S. Concrete: United Materials
• Canadian Concrete: St Marys CBM
• Slag Cement: Votorantim St. Marys Cement U.S. LLC