San Francisco, CA
Inside Alcatraz Quartermaster Restoration
Constructed in 1909, the Alcatraz penitentiary was first constructed as a military prison and later went on to become a maximum-security federal prison by the early 1930s. It is known as one of the most infamous prisons holding criminals like Al (Scarface) Capone, George (Machine Gun) Kelly, Robert (Birdman) Stroud and many more dangerous inmates. The prison closed for good in 1963 after 29 years of operation due to expense related issues. It now stands today as a National Park Service unit with about one million visits from around the world every year.
The Quartermaster Warehouse was created as a multi-use building in 1921 and is still used as a storage, office and workshop facility today. The majority of the structure is made of reinforced concrete with the exterior board-formed walls covered with a thin cement coat throughout. At the basement, mezzanine and first floor the interior columns are reinforced by concrete and wood is used for the second floor. On the upper two floors, there are slabs of concrete for the flooring with a wood frame at the mezzanine level.
Complications That Led to Repair
The structure has taken a beating over the years with the San Francisco Bay causing major deterioration on almost all the concrete exterior elements and by 2010 it was clear the building needed some restoration. With exposed corroding of reinforced steel on the walls, beams, columns and floor slabs. The most severe damage was on the exterior walls but there was also exposed rebar coming to the surface at cracks and spalls in the interior of the building.
In the late 1990s there were a series of assessments that began to evaluate the building’s structural systems and it was clear the warehouse did not meet current seismic and structural codes. Supplementary strengthening methods were designed in the form of new FRP reinforcing on the walls and select floor slabs and new shotcrete on some interior walls. In order for the project to succeed, there was widespread concrete repairs that had to be attended to first.
Sika Product Solution
In the Alcatraz Quartermaster Warehouse, there would be extensive concrete damage in some parts but in others the concrete would be perfectly fine and intact. With that in mind, a comprehensive repair system had to be used on all levels of the restoration, which also meant that the renovated areas had to blend well with the historic concrete finishes making cost a concern due to the amount of repairs needed.
The repair system used Sika® Armatec® 110 on all exposed rebar prior to patching and SikaQuick®VOH and SikaTop® 123 Plus for all patch work needed. Sikacrete® 211 form and pour was used to repair all of the window openings on the structure. SikaTop® 123 Plus was also applied over the exterior of the building surface as a thin “parge” coat. Sika® Ferrogard® 903 (migrating corrosion inhibitor) was applied over the exterior surface as well. Lastly Sikagard® 552W and 550W was applied over the entire exterior as it is an elastomeric wall coating system. These products will keep the Alcatraz Quartermaster Warehouse standing strong for many years to come.