Low Global Warming Potential and Resource-Efficient 3D Printing Cement-Based Concrete

3D printing cement-based materials are often mortars based on a considerable amount of binder materials and high-quality fine sands. Indeed, most of the research and realized projects are 3D-printed fine-grained mortars with round or crushed natural sand. As raw materials for construction materials, especially high-quality sands, are becoming less available, this research project aims to use 100% recycled aggregates (RA) for 3D printing concrete with a maximum grain size of 8 mm. In addition to incorporating 100% recycled aggregates (RA), the goal is to develop 3D printing material with a reduced Global Warming Potential (GWP), e.g., by using low binder – especially Portland cement – contents. Therefore, a packing density optimization was performed to reduce the amount of Portland cement below 200 kg/m3. This paper overviews the first results on fresh and hardened concrete properties using 100% RA for 3D printing concrete and low cement content.