Abstract
The SCENE-B project, part of the New European Bauhaus initiative, explores sustainable concrete solutions for additive manufacturing. This study presents the development of an extrudable concrete mix designed for compatibility with aluminium and other pH-sensitive fibers, while meeting performance requirements for fresh and hardened states. The binder was made with 55% cement replacement by calcined clay, limestone and gypsum. Calcium chloride was introduced as an accelerator to enhance early hydration and stabilization of ettringite. Thermogravimetric analysis and in situ X-ray diffraction revealed rapid formation of stable ettringite, hydrogarnet, and Friedel’s salt, alongside fast portlandite consumption within the first 24 h. Mortar experiments using mostly locally sourced constituents demonstrated excellent flowability, cohesion, extrudability and mechanical properties, without the need for micro-cement or viscosity-modifying admixtures. The mix was validated through nozzle-based extrusion tests and benchmarked against commercial 3D printing mortars. The findings show potential for large-scale extrusion-based concrete printing. This work supports the development of standardized, durable, and resource-efficient materials for additive manufacturing, contributing to circular construction practices and the goals of the New European Bauhaus.