Minima Maxima –Greatness lies in small things
NOEplast formliners simulate stacked
cardboard picture mounts and frames in concrete
Combining historic building forms and fair-faced concrete appears at first glance to be very risky. However, the architects at Worschech Architekten, Erfurt, proved how well a cement-bound construction material can be integrated into a time-honoured ensemble. For the Anger Museum, they used NOEplast textured formliners from NOE-Schaltechnik, Süssen, to realise a fair-faced wall of a form that subtly reflects the function of the building.
The Anger Museum was originally a weigh house and department store, which the Stattholder, who ruled the region on behalf of the Archbishop of Mainz, built to revive the Erfurt economy at the beginning of the 18th century. The historically significant structure in the Erfurt old town underwent a rich and varied series of changes of use before it was developed into a municipal museum of art at the end of the 19th century. However, this resulted in the exhibits being neither preserved nor presented in an acceptable way. Moreover, structural engineering problems, inadequate fire protection, a rotting building fabric and obsolete building services systems made a complete refurbishment of the museum necessary. In their design for the refurbishment, the architects placed particular emphasis on exposing the historical elements from the time of its original construction and the effect of combining them with modern building extensions.
Unconventional wall construction
The Anger Museum, Erfurt, is defined by an internal courtyard surrounded by a number of buildings, each of which once fulfilled a specific purpose. The south wing of the complex was originally a horse shelter, which was open to the courtyard. In 1999, the gap on the open side of the building was filled with a reinforced concrete wall. Three large arched windows were incorporated into the wall. Today, these buildings are populated by works of graphic art, drawings and fine-art prints that need to be well protected from light. For this reason, it was necessary to change the fenestration of the south wing. After experimenting with different construction materials, the designers opted for textured fair-faced concrete, the surface of which was to resemble stacked cardboard picture mounts and frames. Initially the Worschech architects had planned to construct the 33 m long and 12 m high wall on site. But difficult site conditions led to the designers, together with the main contractor Ebert Bau Berga GmbH & Co and the concreting subcontractor Hoffmann Beton GmbH, Gera, to seek an alternative solution. They decided on an unconventional, multi-layer wall construction consisting of an additional layer of insulation, an in-situ concrete layer and finely detailed precast concrete panels. Ebert Bau installed the layers successively in front of the existing wall, then tied them back with anchor bolts. Because the fair-faced elements were manufactured in the precasting works, the conditions were perfect for achieving a high-quality surface finish.
Textured concrete with NOEplast
The architects had very firm ideas about how the finished fair-faced concrete should look. In addition to the refined three-dimensional quality, which provided the desired stacked effect, the concrete had to have a velvety surface. To achieve the impression of stacks of thick paper, it was important that no concrete panel matched the adjacent ones. Some of the panels were therefore turned through 180° to increase the number of possible combinations of elements considerably.
The architects worked closely with NOE-Schaltechnik on the design of the textured formliners. They had a full-scale wooden model made to the original dimensions by an Erfurt cabinetmaker. This provided the basis for the Süssen textured formliner manufacturer to produce three dissimilar polyurethane mats of different widths. Manuela Schleinitz, one of the two project managers for the building alterations, said: "NOE-Schaltechnik were very responsive to our wishes and custom-manufactured the formliners individually to suit the templates provided." To manufacture the fair-faced concrete elements, the Hoffmann Beton GmbH precasting works team glued the formliners into the base of the form with the textured side uppermost, coated them with release agent and filled the form with concrete. NOE-Schaltechnik also offers a special release agent that preserves the formliner surface and ensures that the forms strip perfectly. This is absolutely necessary with fair-faced concrete when using formliners to produce defect-free surfaces and precise edges. After the plastic forms are released from the concrete, the operatives have only to clean them before they are ready to be reused. NOEplast formliners can be reused up to 100 times, depending on how well they have been maintained. The fibreglass fabric backing makes them particularly resistant to the type of mechanical damage that usually occurs on site.
Eternalised in concrete
The architects came up with yet another refinement for the Anger Museum. After all the concrete elements that were needed for the project had been manufactured, they modified the panels by cutting out letters. The words "Minima Maxima" were eternalised in concrete. According to an old proverb, greatness lies in small things. A truth that also applies to formliners because the operatives can use the textured formliners many times, several hundred square metres of textured concrete can be produced from a single plastic mat.
Anger 18, 99084 Erfurt
WPA Worschech Partner Architekten
Fischersand ¾, 99084 Erfurt
- General contractor:
Ebert Bau Berga GmbH & Co. KG
- Concrete works:
Hoffmann Beton GmbH
Linienstraße 11, 07552 Gera