ABSTRACT
Economic development drives a growing demand for primary mineral resources, making soil recycling increasingly important. Global sustainability goals focus on reducing greenhouse gas emissions and promoting a circular economy. The total cement production, including the concrete in tunneling, contributes 5 - 7% of global emissions. Tunnel excavation produces large amounts of soil, often considered as waste, but offers potential for recycling in construction materials. To reduce emissions, new cements with calcined clays are being developed. These clays, derived from thermally treated excavation material, show promise as binders in eco-friendly construction, matching the technical performance of traditional materials. The paper describes the basic concept and presents the required treatment and processing steps. Finally, it is shown that such an eco friendly annular gap grout can have technical properties comparable to those of conventional construction material and can therewith effectively contribute towards achieving sustainable development goals.
