Calcinierte Molasse: Herstellung, Eigenschaften und Einsatzmöglichkeiten

The large quantities of excavation material generated during the construction of underground infrastructure and research facilities pose significant ecological and logistical challenges. Similarly, the planned construction of the approximately 100 km long Future Circular Collider (FCC) as follow-up project of the High-Luminosity Large Hadron Collider (HL-LHC) at CERN scheduled to begin in 2035, is expected to produce extensive amounts of molasse, whose reuse must be considered at an early stage. The aim of the study is the experimental investigation of the suitability of thermally activated molasse for use in hydraulically bound and alkali-activated materials. The material, originating from the Geneva Basin, was first ground, calcined, and subsequently used to produce test brick specimens. The mechanical properties were examined using three-point bending tests and uniaxial compressive strength (UCS) tests after 7, 14, and 28 days. The test results provide an initial assessment of the calcined molasse in terms of its reactivity and strength development. Only the alkali-activated specimens showed sufficient strength development, while the hydraulically bound bricks exhibited low compressive and flexural strengths. Therefore, calcined molasse shows particular potential for use in resource-efficient, CO2-reducing construction materials when alkali-activated.