The Zeitz Museum of Contemporary African Art in Cape Town South Africa was designed by Heatherwick Studios, converting a historic grain silo building into a contemporary art gallery to showcase African artists from the 21st Century. The silos were built in 1921-24, and have long dominated the Cape Town skyline at over 55m high. The existing silo building is comprised of 42 vertical cylinders, creating challenges to the traditional requirements of artwork hanging and display.
The architects developed two strategies to create a functional gallery space within the silo building. The first approach is to remove internal partitions to create 80 functional rectangular exhibition halls. Secondly, an atrium was created by carving a void through a cluster of silo volumes. This dynamic intervention into the existing concrete silos required a technical resolution to ensure that the concrete performed structurally and aesthetically in harmony with the structure as a whole.
The walls of the original silos were only 170mm thick, an additional 420mm was added to the internal surfaces to ensure the structural integrity of the forms once the atrium void was cut. The technical difficulty of this task, plus unforgiving top lighting made the raw uneven internal surfaces unsuitable for the final building. The architects selected a range of KEIM mineral products to rectify the surface and bring it up to the level of detail and quality required.
To rectify the concrete firstly the unevenness of the internal surface was leveled out by removing projections, filling recesses, and rectifying defects. Secondly, the surface texture of the concrete was evened out and gloss graduations were removed by pre-wetting the walls, and applying a release agent to release residues and oily stains. Then the KEIM Concretal-Lasur was applied to complete the process. KEIM Concretal-Lasur is a thin-layer glaze also called a mineral glaze. As a mineral coating, it preserves the visible, open-pored structure of the concrete rather than creating a film on the surface. KEIM worked with the architects to ensure that the correct color was created to maintain an appearance as close as possible to the original concrete. The flexibility of the KEIM Concretal-Lasur product allowed an exact color match and resulted in 4,500 square meters of concrete restoration appearing natural and raw. This process allowed the architects' vision and this unique space to come to life.
KEIM products used
- KEIM Betonschnellreiniger (Concrete cleaner)
- KEIM Concretal-MKH
- KEIM Concretal-Feinspachtel (Fine filler)
- KEIM Concretal Mörtel-R (Mortar)
- KEIM Concretal-Lasur
- KEIM Concretal-Base resp. KEIM Concretal-Fixativ (Dilutions)
