Short fiber reinforced geopolymer composites manufactured by extrusion

Geopolymer composites reinforced with short polyvinyl alcohol (PVA) fibers have been manufactured using the extrusion technique. The extruded products were thin plates with 6 mm thickness. It was demonstrated that short fiber reinforced geopolymer composites (SFRGCs) could be extruded without additional rheological modifier. Bending tests have been conducted with the extruded samples to investigate their mechanical properties. The fiber failure patterns in SFRGCs with various formulations were examined by scanning electron microscope and energy dispersive x-ray analysis techniques. The experimental results showed that the addition of PVA fiber could largely increase the ductility of SFRGCs, resulting in fiber failure modes changing from brittle to ductile. The effects of varying the amount of fly ash on the flexural behavior of various SFRGCs were also investigated. The SFRGCs incorporating small percentage of fly ash showed higher flexural strengths but smaller defections, while the SFRGCs incorporating a large percentage of fly ash had lower flexural strengths, but larger deflections. This could be attributed to the change of the bonding between fiber and matrix that led the change of failure mode from fiber fracture to fiber pullout.