SALT WATER CLAY Turns Excavated Soil Into Circular Building Material

A research project in Esbjerg, Denmark, explores how locally excavated clay soils can become sustainable building materials for community architecture. Developed by Tobias Trübenbacher and Tillmann Gebauer at the Technical University of Munich (TUM), SALT WATER CLAY combines regional resources, circular production methods and material reuse in one architectural system.

The project recently received recognition in the architecture category of the Green Product Award.

Turning Excavated Soil Into Building Materials

SALT WATER CLAY focuses on the development of a neighbourhood hub in Esbjerg’s International Kvarter district. The design is based on extensive research into the region’s geological, climatic and social conditions. In particular, the team investigated how soil excavated from a planned rainwater retention basin could be reused as a construction resource.

Together with Bauhaus Earth, the designers carried out material testing and construction-standard analyses on the local clay soils. As a result, they developed a system that transforms the excavated earth into load-bearing clay bricks directly on-site.

At the centre of the proposal is a circular “field factory”. This temporary production facility manufactures clay bricks for the project. Afterwards, the structure gains a second life as a multifunctional community centre. In this way, the production process itself becomes part of the final architecture and strengthens the site’s local identity.

Hybrid Construction With Reused Wind Turbine Segments

Alongside the neighbourhood centre, the proposal includes a student housing complex with 90 micro-apartments. The ensemble combines locally produced clay bricks with reused concrete segments from decommissioned wind turbine towers.

These former wind turbine elements arrive from the nearby harbour and serve as structural components within the buildings. Consequently, the project demonstrates how large-scale industrial waste streams can be repurposed for architectural applications.

In addition, the attached greenhouses perform several functions. Initially, they support the solar drying of the clay bricks. Later, they help regulate the indoor climate of the buildings. During winter, the spaces transfer solar heat into the interiors. During summer, they encourage natural ventilation through a chimney-effect airflow system.

Architecture Based On Bioregional Material Cycles

SALT WATER CLAY presents architecture as a circular relationship between material, place and community. By treating excavated soil as a valuable local resource instead of waste, the project proposes a low-impact alternative for future construction.

Moreover, the design reduces transport-related emissions by using regional materials and on-site production methods. At the same time, it highlights the growing importance of bioregional construction strategies that combine sustainability, reuse and social value.

Ultimately, the project demonstrates how architecture can connect circular material systems with long-term community use while creating a strong sense of place.

Source & photos: Green Product Award / BauNetz