The cast clay pavilion on the HSLU campus is the first building whose load-bearing structure has been constructed exclusively using earth-based and recyclable building materials developed by Oxara. In a multi-year research collaboration between the Institutes of Architecture and Civil Engineering at HSLU and Oxara’s various industrial partners, specific structural and construction principles were tested and implemented in a prototype pavilion. The spaces took on their form and character through a comprehensive exploration of the properties of the various material mixtures and processing methods. Nossim (unstabilised cast clay) and Oulesse (containing recycled residual cement from demolition waste) were used to cast the foundations, walls and floors, and to prefabricate the blocks for the compression arches and vaults. The behaviour of the materials is being measured and evaluated over a three-year period of use in order to prepare for standardisation and widespread application.

Whilst the earth-based building material exhibits excellent properties in terms of thermal storage capacity and the ability to absorb compressive loads, tensile loads are absorbed via a wooden ring beam and longitudinally tensioned steel cables. The hybrid structure adheres strictly to ‘Design for Disassembly’ principles and functions without any penetrations or destructive fastening methods. The additive elements of the building envelope and the roof are clamped, braced or tensioned, and can be reused directly at the end of their service life. The material-appropriate construction gives rise to surprising spatial qualities. Compression arches and vaults are reminiscent of archaic models, whilst the object-like assembly of all components is an expression of optimistic contemporary architecture.