Technologies for improving buildability in 3D concrete printing

Abstract

Buildability is the ability to 3D print by adding concrete layer by layer continuously to the required level without significant deformation or collapse of the freshly printed component. This paper presents a systematic review of the reported studies to improve the buildability of concrete. The paper also presents original concepts and some results for improving the buildability of geopolymer concrete. Two methods to enhance the buildability are discussed: (1) Additives during initial mixing of concrete (2) Buildability enhancement at the print-head by an intervention (set-on-demand). The former method is the most widely studied, however, it affects the pumpability. The latter includes mixing accelerators, heating, ultrasonication, or magnetorheological control, performed at the print-head to rapidly increase the yield strength of the material immediately prior to extrusion. This method does not affect the pumpability of the mix until it reaches the print-head. Finally, the prospects of a new set-on-demand method are presented.