3. Result and discussion
3.1. Pozzolanic particles
The XRF results as presented in Table 2 show that the major
pozzolanic components of SiO2 + Al2O3 + ferric oxide (Fe2O3) for
POFA and FA are 74.24% and 87.14%, respectively, hence satisfying
the requirements of ASTM: C618-12a. Fig. 2 shows the micrograph
of the pristine POFA and FA; it can be seen that the FA consists of a
series of spherical vitreous particles of different sizes. While usually
hollow, some of these spheres might be almost intact or appear
within other small size spheres in their interior [16,33]. The FESEM
morphology of the POFA powder suggests that the sample consists
of both agglomerated and angular particles. As shown in Table 1,
the specific gravity of POFA is about 87% that of FA. The
Brunauer–Emmett–Teller (BET) surface area of the POFA and FA
are 12.92 and 2.96 m2/g, respectively. The higher BET of POFA would
lead to the requirement for additional water to achieve the same
degree of workability as that of FA based geopolymer mortar.