Robotic Rammed Earth-Concrete (RREC): A Novel Additive Manufacturing Technology to Strengthen Rammed Earth Structures by Integrated Rammed Concrete Parts

Rammed earth is part of our building culture and is a suitable solid construction method for load-bearing structures. The advantages are its global availability, low ecological footprint, and complete reusability. However, challenges arise from the manual construction processes, which makes manufacturing time intense and leads to significant scatter in the compressive strengths. The robotic rammed earth process (RRE) developed at the Institute of Structural Design at TU Braunschweig (ITE) unifies formwork and compaction in one process step and enables the automated manufacturing of rammed earth components with consistent material properties. Nevertheless, even robotically rammed earth components have a significantly lower load-bearing capacity compared to concrete structures and are, therefore, very limited in their application. In order to increase the structural performance of rammed earth elements, a new additive manufacturing method has been developed at the ITE that combines rammed earth and rammed concrete in one-step automated process and enables the manufacturing of structural components with hybrid materiality. The so-called robotic rammed earth-concrete technology (RREC) makes it possible to utilise the different performance capabilities of the two materials, earth and concrete, in a customised way. RREC can be used for structural or architectural purposes, e.g. structural optimisation or erosion reinforcement, and ensures material-specific separation and recycling of materials at the end of their service life. The paper presents initial research results on material-process interactions in automated processing material studies, tool developments and structural design.