Properties of 3D-Printable Ductile Fibre-Reinforced Geopolymer Composite for Digital Construction Applications

Two main limitations of extrusion-based 3D concrete printing process are the incorporation of conventional steel bars and the limited range of printable concretes. To tackle both limitations, this paper investigates feasibility of developing a 3D-printable ductile fibre-reinforced geopolymer composite (DFRGC) for digital construction applications. Instead of the conventional cement binder, a “just-add-water” geopolymer binder was used for production of the 3D-printable DFRGC, which considerably improves its sustainability performance and commercial viability in the construction industry. A series of experiments including bulk density, apparent porosity, compression, and flexural tests were conducted to characterize the mechanical properties of the 3D-printable DFRGC. The effect of number of printed layers on the mechanical properties of the 3D-printable DFRGC was also investigated. Further, dependency of the compressive strength of the printed sample on the testing direction was also evaluated. The developed 3D-printable DFRGC exhibited deflection-hardening behaviour in flexure with high modulus of rupture of up to 10.2 MPa and deflection capacity of up to 5.3 mm. Therefore, the feasibility of developing 3D-printable deflection-hardening ductile geopolymer composites was established. The results also showed that the compressive and flexural performances of the 3D-printed DFRGC specimens depended on the testing direction and number of printed layers.