The historic San Francisco-Oakland Bay Bridge is a vital artery for the 280,000 vehicles traveling between the two major California cities daily. However, by 2008, after 7 decades of wear and tear, government officials had little choice but to build a new, state-of-the-art structure.
BAY BRIDGE
Completed in 1936, the 8.4-mile-long Bay Bridge is located between two major fault lines, making the structure susceptible to intense seismic activity. After a 250-ton section of the eastern span collapsed during the 7.1 magnitude Loma Prieta Earthquake in 1989, officials began planning for a new eastern span, one that incorporated modern seismic safety technologies.
The first stage of construction began in August 2008 with the building of temporary structures to support the new bridge’s falsework. The support structures were built on Yerba Buena Island in the middle of San Francisco Bay and in the bay itself. The structures will support the weight of the new bridge deck until the main cable for a self-anchored suspension (SAS) structure can be installed to hold the bridge deck.
The project’s subcontractors—a joint venture between Dutra Construction and Traylor Bros. Inc.—working on behalf of the California Department of Transportation, chose QUIKRETE® General Purpose Non-Shrink Grout and Flowcrete V. Crews used the QUIKRETE products for the bridge foundation pier, grouting 17 support towers erected as part of the SAS structure.
For pile voids less than 6 inches, crews used QUIKRETE General Purpose Non-Shrink Grout, mixed to a fluid consistency. The grout is a high-strength, non-metallic Portland cement-based material with expansive additives. Its non-shrink characteristics make it stable and capable of handling high load transfers.
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QUIKRETE General Purpose Non-Shrink Grout can be mixed to a plastic, flowable or fluid consistency, and reaches 8,000 psi in a fluid consistency in 28 days. It complies with ASTM C1107 and Army Corp of Engineers CRD 621.
Flowcrete V, a flowable, shrinkage compensated, structural concrete, was used to fill the void between the inner and outer piles wider than 6 inches on the Bay Bridge project. It is designed as an original or repair concrete in situations that require a high-quality concrete with a maximum aggregate size of 10 millimeters. It can be mixed to any consistency—from stiff plastic to flowing and requires no mechanical vibration to consolidate the mix.
“Given the unique nature of this project, crews needed a product that was easy to work with and would provide reliable results each time,” says Steve Rafael, a QUIKRETE regional sales representative. “By using QUIKRETE General Purpose Non-Shrink Grout and Flowcrete V, crews had a product that made this aspect of the project a little easier.”
In total, crews on the Bay Bridge used 126-3,000# bulk bags of QUIKRETE General Purpose Non-Shrink Grout and 104-3,000# bulk bags of Flowcrete V. Once completed, the SAS is expected to be one of the largest structures of its kind in the world.
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ANTIOCH BRIDGE
In another bridge project in San Francisco, QUIKRETE products were used to upgrade the Antioch Bridge. The 9,437-foot-long bridge was developed after the 1971 San Fernando earthquake and opened in 1978.
QUIKRETE provided California Engineering, the subcontractor selected by the California Department of Transportation, with 4,000-50# bags of QUIKRETE Non-Shrink Precision Grout, a high-strength, non-metallic grout designed for precision grouting and general construction applications. QUIKRETE Non-Shrink Precision Grout complies with ASTM C1107 and Army Corp of Engineers CRD 621, reaches 14,000 psi in 28 days and remains in a flowable state for 25 minutes.
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As part of the project, crews are completing a seismic retrofit to 41 piers supporting the bridge. QUIKRETE Non-Shrink Precision Grout was used to fill in the 2-inch void surrounding the newly installed isolation bearings. Started in November 2010, the Antioch Bridge seismic retrofit has been completed this year. ■
For More Information:
The QUIKRETE® Companies is the largest manufacturer of packaged concrete and cement mixes in the U.S. and Canada, and an innovative leader in the commercial building and home improvement industries. For additional information, call 800.282.5828, or visit www.quikrete.com.
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Modern Contractor Solutions, August 2013
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