The Eastern Span of the Bay Bridge was built to provide an earthquake-resistant replacement for the existing 1930s-era steel span bridge. The first-ever, single-tower, self-anchoring suspension bridge project spans Oakland, CA, on the east with Yerba Buena Island in the center of San Francisco Bay. The bridge project took 13 years from design to completion in 2014 and was over $6.4 billion in total cost. The Bay Bridge project entailed a number of rigorous requirements such as concrete durability, CO2 reduction, strength, and pumpability. To meet these requirements, Central Concrete engineered more than 40 specialty mixtures— optimized to deliver the aggressive performance specified for this large-scale, technically challenging project. The mixtures were also designed to reduce the Bay Bridge’s carbon footprint by using 25 to 50% supplementary cementitious materials.
Slag cement was an integral part of the multiple mixtures to help reduce the overall carbon footprint, increase the concrete strength, increase durability, reduce shrinkage, reduce heat of hydration and creep, and increase ease of placement of the concrete. A majority of the concrete was a high-performance 8000 psi (>55 MPa), 56-day mixture with a 0.035 low-shrink design and stringent creep requirements. That mixture included slag cement at a 30% replacement factor and achieved strength requirements prior to 56 days and enabled the concrete supplier to maintain the stringent construction schedules.
Project credits: Caltrans, Owner and Architect; American Bridge/Fluor JV, Engineers; C.C. Myers, Inc., Conco, Flatiron Construction Corp., and MCM Construction, Inc., General Contractors; Condon Johnson & Associates, Inc., Murga Strange and Chalmers, and Vanguard Construction, Subcontractors; Central Concrete Supply Co., Inc., Concrete; and Lehigh Southwest Cement Co., Slag Cement.