Mechanical improvement of continuous steel microcable reinforced geopolymer composites for 3D printing subjected to different loading conditions

Sufficient reinforcement is crucial for three-dimensional (3D) printed concrete structures. In this study, continuous and simultaneous micro-cable reinforcing methods are investigated to accommodate the 3D flexible and automatic characteristics of additive manufacturing processes, and to satisfy the mechanical-property requirements for construction applications. Different manufacturing-related micro-reinforcements and printing configurations are designed for 3D printing cable-geopolymers. The specimens were subjected to three different types of loading conditions (compressive, shear, and tensile) to gain a better understanding of the composite behavior. The results revealed interesting behaviors: under compressive loadings, the confinement effect of the micro-cables is fundamental in producing additional strength, ductility, and toughness. The print path must be considered for determining the confinement levels. Micro-cables increase the compressive strength by 50.0% in a certain print path. The shear strength depends primarily on the geopolymer weak planes' directions between two filaments instead of the embedded cable reinforcements. The tensile response is primarily governed by the micro-cable reinforcements and the configurations, which depend on the print paths. In certain configurations, the micro-cables result in 158% and 43.8 times increase in tensile strength and strain, respectively. This study provides valuable insights into the behavior of 3D-printed geopolymer composites with micro-cable reinforcement, which is necessary for designing and manufacturing complex structures using this novel reinforcement method.