Influence of kenaf stalk on printability and performance of 3D printed industrial tailings based geopolymer

Abstract A new 3D printing material for advanced construction was innovatively proposed, based on alkali-activation of industrial waste and agricultural residues, including fly ash (FA), ground granulated blast furnace slag (GGBFS), kenaf straw core (KSC) and kenaf fiber (KF). For evaluating the extrusion and printing performance, viscosity evolution, shape retention ratio, cross-section characteristics and mechanical properties of different geopolymers were investigated. Results shown that viscosity recovery and thickness shape retention of geopolymer with KSC and KF jointly were increased 189.19% and 67.63% respectively, compared with control group. Meanwhile, adding 1.5% KSC and 0.2% KF based on the mass of FA and GGBFS led to a dry density decrease from 1749.32 kg/m3 to 1560.60 kg/m3, which could be highly conducive to implementation of multi-layer printing. Furthermore, the skeleton function of KSC and bridging effect of KF in geopolymer were confirmed at the micro level by scanning electron microscopy, and synergistic effect of KSC and KF contributed to the satisfactory performance of printed specimens. These results provided not only a sustainable mode for intelligent construction and development, but also an innovative strategy for full utilization of industrial tailing and agricultural residues.