The shape, particle size and surface area of POFA and FA
particles affect the hardened mechanical properties of geopolymer
mortar. The POFA particles with higher BET and crumpled shape
increased the water demand to produce a workable geopolymer,
while spherical FA particles enable workable mix with reduced
amounts of water. Consequently, the increase in the evaporable
water in POFA based geopolymer resulted in slightly more porous
material. The low specific gravity of the POFA along with its inherent
raw material density and shape are capable of trapping air,
resulting in a porous geopolymer mortar with about 6% less
density compared to FA based mortar.