A facelift on Alcatraz Island

Words: Matthew AdamsThe QUIKRETE Co.s, recently supplied shotcrete in 3,000-pound bulk bags for a restoration project on Alcatraz Island, also known as “The Rock.”

Boulderscape, a design architect specializing in shotcrete application, used QUIKRETE Shotcrete MS — Fiber Reinforced and QUIKRETE Shotcrete MS to successfully repair and stabilize a failing slope on the 22-acre island.

In addition to facing dangerous application conditions, a condensed six-week shotcrete schedule was required to avoid disruptions to regular tour operations, while considering the habitat and migration patterns of local sea birds.

“Navigating a variety of unique factors made this a very fulfilling project for everyone,” says Steve Jimenez, senior VP commercial sales for Boulderscape. “We couldn’t start until the indigenous birds migrated from the island in November, and we had to complete our portion of the work before the birds returned in February.

“This meant everything had to be expedited, starting with the delivery of material,” he continues. “Beyond the challenging schedule, the application process was full of danger. The nozzlemen had to be hoisted more than 60 feet in lifts to spray-apply the shotcrete before sculptors repelled down the cliff to shape the material. The end result was a structurally sound slope that matched the surrounding environment.”

In one weekend, 131 bulk bags of Shotcrete MS — Fiber Reinforced and 126 bulk bags of Shotcrete MS were delivered to Alcatraz Island for the project. QUIKRETE delivered16 truckloads of material to Pier 50 in San Francisco that were later shipped on two barges to Pier 33 on Alcatraz Island. It was offloaded at night by crane, one-by-one, before finally being transported to the jobsite on trailers pulled by four-wheel, all-terrain vehicles.

Shotcrete MS — Fiber Reinforced is a single-component Micro Silica enhanced repair and restoration material that achieves more than 9,000 PSI at 28 days, and features very low rebound and permeability characteristics.
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