Large Particle 3D Concrete Printing—A Green and Viable Solution

The Large Particle 3D Concrete Printing (LP3DCP) process presented in this paper is based on the particle bed 3D printing method; here, the integration of significantly larger particles (up to 36 mm) for selective binding using the shotcrete technique is presented. In the LP3DCP process, the integration of large particles, i.e., naturally coarse, crushed or recycled aggregates, reduces the cement volume fraction by more than 50% compared to structures conventionally printed with mortar. Hence, with LP3DCP, the global warming potential, the acidification potential and the total non-renewable primary energy of 3D printed structures can be reduced by approximately 30%. Additionally, the increased proportion of aggregates enables higher compressive strengths than without the coarse aggregates, ranging up to 65 MPa. This article presents fundamental material investigations on particle packing and matrix penetration as well as compressive strength tests and geometry studies. The results of this systematic investigation are presented, and the best set is applied to produce a large-scale demonstrator of one cubic meter of size and complex geometry. Moreover, the demonstrator features reinforcement and subtractive surface processing strategies. Further improvements of the LP3DCP technology as well as construction applications and architectural design potentials are discussed thereafter.