Development of ultra-ductile strain hardening 3D printed concrete composite utilizing critical fiber volume and coarse aggregate

This study presents a promising approach of integrating coarse aggregates and steel fibers (smooth straight and corrugated) into 3D printed concrete to enhance both strain-hardening and ductility properties. The research delves into the engineering design of fiber reinforced 3D printed concrete by analysing the effect of critical fiber volume and coarse aggregate addition on concrete tensile properties. The combination of coarse aggregate and fiber enhances the material ability to withstand increasing loads by promoting plastic deformation, while mitigating the crack formation and propagation. Experimental methodology for engineering design of fiber reinforced 3D printed concrete is elucidated via critical fiber volume analysis, strain hardening analysis, and ductility assessment under direct tensile loading. The results indicate synergistic effect of corrugated fibers and coarse aggregates on the tensile properties and unlike straight smooth fiber, corrugated long fibers significantly contribute to excellent strain hardening behaviour. The new 3D printed concrete composite developed in this study exhibited distinctive yield point with high strain hardening factor (1.62), ductile factor (10.86), and enhanced energy absorption capability (+105 kJ/m³). These enhanced properties make the material particularly suitable for applications in seismic-resistant structures and other load-bearing applications where ductility and energy absorption are critical.