This paper describes a novel digital earthen fabrication concept referred to as Sprayed Earth Additive Manufacturing (SEAM), where earthen material is sprayed robotically with pressure in order to create a three-dimensional structure. Compared to processes based on material-extrusion, the adhesion between the sprayed layers is improved, the addition of material is controlled, and spatial flexibility is enhanced. Additionally, the possibility of adding natural fibers to the sprayed earthen mix allows enhancing the strength and the shrinkage behavior of the earthen material. The paper starts by addressing the current state of the art on reinforcement of earthen material, optimization of the spraying technique and automation in the construction process. It then demonstrates the applied methodology, early material research, explored spraying parameters such as the influence of air volume flow, nozzle velocity and nozzle to strand distance on the layer geometry and the implemented robotic fabrication setup for integrated fiber reinforced spraying. A novel concept of fiber integration, where a continuous fiber strand is chopped and added to the sprayed earthen material directly at the nozzle, was tested for the first time. Finally, the paper presents a series of the latest experimental results, reflections on the overall material reinforcement investigations and concludes with potential future explorations needed for the research.

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