The influence of nano-additives in strengthening mechanical performance of 3D printed multi-binder geopolymer composites.

• Development of novel 3D printable geopolymer. • Nano-additives improved the mechanical performance of 3D printed structures. • The microstructural analysis revealed the micro-crack arresting effect of nano additives. • The shape retention and buildability of geopolymer was improved with incorporation of nano additives. • Rheology measurements play a crucial role in the selection of printable feedstock. The weak mechanical properties the 3D printed parts can limit the competence of this technology when compared to conventionally cast-in-mold cementitious composites structures. However, experimental results in this study showed that the incorporation of nano additives could improve the mechanical property of printed structures. Six geopolymeric mixtures were designed and tested for their flow-ability, shape stability, buildability and mechanical performance. Different dosage of nano graphite platelets (NGPs) ranging from 0.1% to 1%, by the weight of geopolymer, were incorporated to the best performing geopolymer. The 3D printed geopolymer with 1% of NGPs increased the flexural strength by 89% and 46% compared to the same 3D printed and casted geopolymer without any NGPs, respectively. The same increase for compressive strength was 28% and 12%. Moreover, the geopolymer mix containing 1% of NGPs demonstrated the best shape retention and buildability. [ABSTRACT FROM AUTHOR]