A 3D printer of cement mortars based on initial deposition of dry materials

The paper presents the studies of implementation of an equipment for producing mortar elements through a 3D printing process, aiming to demonstrate feasibility and challenges, with the intent of a future upscaling to actual concrete production. The techniq ue for 3D printing is based on the additive method, with an innovative approach in regard to the deposition of materials. Indeed, the cement/sand are deposited by layers into their final positions. After the deposition of each layer, water is sprayed in a controlled manner. When a given set of layers is deposited, compaction is applied to the entire part. This technique has the interesting feature of allowing to differentiate mortar composition at different regions of the produced elements, with possibility of structural optimization of the spatial use of cement. The feasibility of the developed equipment and produced parts is demonstrated, and discussions are held in regard to challenges and future developmentsPOCI-01-0145-FEDER-007633 (ISISE), funded by FEDER funds through COMPETE2020 -Programa Operacional Competitividade e Internacionalização (POCI), and by national funds through FCT -Fundação para a Ciência e a Tecnologia. FCT and FEDER (COMPETE2020) are also acknowledged for the funding of the research project IntegraCrete PTDC/ECM-EST/1056/2014 (POCI-01-0145-FEDER- 016841)