A Critical Review of 3D Printed Fiber-Based Geopolymer Concrete (2025-11)¶

Additive manufacturing with geopolymer binders has emerged as a transformative pathway for sustainable construction, offering reduced carbon emissions, resource efficiency, and digital design flexibility. This review uniquely connects two fast-evolving areas 3D printed geopolymer technology and fiber-reinforced composites by systematically linking fiber type, dosage, and orientation to rheological behavior, mechanical performance, and current limitations. Geopolymers, synthesized from industrial by-products like (e.g., fly ash (FA), ground granulated blast-furnace slag (GGBFS), rice husk ash (RHA), silica fume (SF), coal bottom ash (CBA), metakaolin (MK), etc.), serve as binders in 3D printed fiber-based geopolymer concrete (3DP-FGC), activated by alkaline solutions such as sodium hydroxide (NaOH), sodium silicate (Na2SiO3), and potassium silicate (K2SiO3). The integration of various fibers such as (e.g., polypropylene (PP), polyvinyl alcohol (PVA), polyethylene (PE), steel, basalt, carbon, etc.), has been shown to significantly improve fresh and hardened properties. The review delves into rheological behaviors like flowability, extrudability, and buildability, as well as mechanical properties compressive, flexural, and tensile strengths. 3DP-FGC exhibits promising mechanical and environmental benefits, but challenges persist, such as achieving uniform fiber dispersion, optimal mix designs, and reliable interlayer bonding. The large-scale deployment of 3DP-FGC, however, remains limited by material-related issues, process constraints, and performance concerns that require further investigation. Ultimately, 3DP-FGC offers a pathway toward more resilient and structurally innovative construction, aligning with the goals of reducing carbon footprint, material waste, and labor demands.