Additive manufacturing of fully-recyclable wall systems made from renewable materials

The content of the project is to develop a research-based, robotic, additive manufacturing (3D printing) process for wall components using bio-based raw materials, with the raw materials coming primarily from by-products of the paper, starch and sawmill industries. A mixture of lignin, starch and sawdust is printed, either in powder form or using a granulate as an intermediate product. The underlying problem concerns four issues: (1) the worldwide shortage of non-renewable and renewable raw materials (2) the current main use of inorganic building materials (concrete and steel) in the construction industry as well as the (3) to date still inefficient use as well as also missing circular approaches in the use of renewable raw materials and (4) the low productivity in the construction industry. The two overarching objectives of the proposed R&D project are: (1) Development of a bio-based, fully recyclable material consisting exclusively of by-products of the paper, starch and sawmill industries and (2) Development of a robotic additive manufacturing process for wall components suitable for the use of the developed material. The combination of the novel material and the additive manufacturing process, which allows a radical simplification of the production of individual components, can result in an enormous technological leap in the use of renewable resources compared to the current state of the art and practice. Wood waste could be processed directly without complex intermediate processing steps. By mixing it with the developed “biomix” (biological glue) and, if necessary, other additives, enabling different modifications such as better water or fire resistance, a new type of building material is created. Based on previous research mixing all components in a dry sate is possible, therefore allowing for a dry extrusion before water is added as final step before compression under additional heat treatment. By using only by-products of the wood industry, the degree of utilisation can be increased from currently max. 60% (for sawn timber) to >90%. With the completion of the research project, comprehensive knowledge on the production processes as well as the chemical and mechanical properties of the new material will be available. This expertise will be supplemented by the acquired knowledge on the additive manufacturing process using bio-based materials and a fully functional additive manufacturing tool for mounting on industrial robots (and also suitable for gantry systems). The fabrication of up to 200mm thick walls will be possible. Furthermore, extensive LCA data will be available, considering raw material supply and transport (according to EN 15804: A1-A2), the manufacturing process (A3), deconstruction and demolition (C1) as well as a forecast for the use stage (B). The results will be shown within a full-scale 3m long and 3m high demonstrator wall. With this project, a completely new dimension in terms of automation, recyclability, and biological resource-efficient construction will be reached.