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ICRI 2005 Project Award Winner
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Award of Excellence: Historic Category

Alcatraz Cellhouse
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San Francisco, California

Submitted by Sika Corporation

Alcatraz Cellhouse

National Park Service
San Francisco, California

Project Engineer/

Wiss, Janney, Elstner Associates, Inc.
Emeryville, California

Repair Contractor
Watertight Restoration, Inc.
San Francisco, California

Material Supplier/

Sika Corporation
Lyndhurst, Maryland

General Contractor
Miller/Watts Construction, Inc.
Richmond, California

Construction Manager
Parsons Brinckerhoff
San Francisco, California

Alcatraz is one of the most famed tourist sites in the United States and welcomes nearly 1.4 million visitors annually. “The Rock” was made famous as a prison that was virtually inescapable because of its remote location in the middle of San Francisco Bay, and its notorious occupants, including Al Capone, “Machine Gun” Kelly, and others.

Alcatraz Cellhouse, the most visited and prominent building on Alcatraz Island, was also the largest reinforced concrete building in the world at the time of its completion in 1912. It was reinforced with square and twisted reinforcing steel, a style that was sometimes used in the early 20th century concrete buildings.

Ironically, what made Alcatraz so famous and difficult for prisoners to escape from was also the cause of its demise. The cold salt waters of San Francisco Bay and the windy conditions of the area caused airborne chlorides to deposit themselves onto the concrete structures, and after decades of exposure and neglect, ultimately penetrate through the concrete to the steel reinforcement. In addition, atmospheric carbon dioxide also caused the concrete to become carbonated over the years, lowering its pH, and causing corrosion of the reinforcing steel. The degradation of the structures on Alcatraz Island, along with the high operating costs of the prison, caused Alcatraz to shut down as a penal institution in 1963.

Alcatraz was occupied by various groups over the next decade with little attention made to maintenance or upkeep. The structures continued to degrade, and chloride induced corrosion caused the reinforcing steel to expand, cracking and spalling the concrete. In 1972, Alcatraz Island was turned over to the Golden Gate National Recreation Area. However, due to limited funds from Congress to the National Parks Service, another 30 years passed before any significant rehabilitation program took place on Alcatraz. When money finally became available, a major concrete repair and seismic strengthening program was initiated.

This was an extremely challenging project for the contractor due to the remote location of the island and the fact that the facility remained open to tourists during construction. In addition, being a landmark building, the appearance of the Alcatraz Cellhouse could not significantly change, including details such as graffiti that were required to remain intact and pipes that could not be relocated.

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