At almost 9 metres high, the tower at the Ziegelei-Museum is an observation tower, a kiln and an experiment.
From the observation deck, the entire museum landscape can be seen: the biotope, which is now a nature reserve, the forest and the residential and production buildings. From here, the entire process of brick and tile production can be traced, beginning with the raw materials wood, water and clay. Clay was extracted from the clay pit (the modern-day biotope), stored and processed and dried in the brickworks. Dried bricks and tiles were fired in the brick kiln and used in construction, demonstrated by the bricks of the museum building and the tiles on all the roofs.
The kiln in the historic brickworks can no longer be used for safety reasons. This makes the kiln built into the tower all the more significant. The open-top kiln, which has two stoke holes on the southern outer side of the tower and an inner grate which holds the fired material, was put to use in summer 2022. Based on historic models, an experimental firing was carried out, using lime and firing handmade bricks and tiles. The inside of the kiln is accessible from the spiral staircase inside the tower. The wooden cover, visible on the observation deck, is removed during the firing process.
The experiment in building with rammed earth is a contribution to the development from traditional building techniques to a sustainable shift in the construction industry.
Earth is an ecological and widespread building material. It is produced during almost every construction process and is usually deposited at a high cost in gravel pits.
Rammed earth was part of the historic architectural repertoire in the areas around Lyon, Geneva and Thurgau. It made a significant contribution to the development and use of concrete and was ultimately replaced by it.
Today, rammed earth has been rediscovered. With the rise and necessity of sustainable, resource-saving and low-CO2 construction, the potential uses of rammed earth are being explored. It is resistant and resilient, and rammed earth façades are surprisingly weather-proof with the implementation of certain protective elements (e.g. proper drainage to prevent erosion). However, the wind and earthquake resistance of tall builds with this material must be tested and analysed. For this purpose, the kiln tower uses prestressing cables, similar to the threaded bars used in prestressed concrete.
The settlement and creep patterns of the rammed earth are constantly monitored, contributing to new research findings.
The natural materials should not only be recyclable, but also reusable. This was considered in the planning of the tower, which is constructed with blocks. These blocks, as well as the foundation of the tower, can be dismantled. The tower can therefore be reconstructed elsewhere.
A decisive factor for the success of rammed earth is its cost-effectiveness in construction and use. Steps to achieve this include prefabrication independent of the weather, the mechanisation of production, reducing transport distance and testing ideal material combinations. Last but not least, rammed earth construction also aims to be aesthetically pleasing, such as our kiln tower as a Zuger landmark.
PDF with project information (German)
Contributors
Client: Verein Ofenturm Ziegelei-Museum Cham.
Driving force: Dipl. Architekt ETH Prof. des. Roger Boltshauser.
Engineering, planning support, organisation and construction management: MSc. ETH-Bauing. Felix Hilgert and Lukas Baumann, Lehmag AG.
Preliminary design: Robert Gentner and Regina Pötzinger, students of TU München.
Further development of design: Students of ETH Zürich and co-workers of Boltshauser Architekten AG.
Participation in the rammed earth construction: students of various universities.