Materials and Method
Raw Materials Preparation
Fly ash (FA) was lignite fly ash from
Mae Moh power plant in the northern part of
Thailand. Bagasse ash (BA) was a waste
from sugar refinery of Kaset Thai Co., Ltd., in
Nakhon Sawan province, central Thailand.
Rice husk ash (RHA) was obtained from rice
mill in the central part of Thailand. FA, BA
and RHA were ground by a centrifugal ball
mill until whole of the fine particles passed
through sieve No.325 mesh, i.e., < 45 μm
particles were prepared as raw materials in
the research.
Sodium silicate solutions (Na2SiO3)
(13.8%Na2O, 32.2%SiO2 and 54.0%H2O) and
10 molar sodium hydroxide solution (10M
NaOH) (commercial grade) were used as the
alkali activators.
Characterization of Initial Materials
FA, BA and RHA were determined by
X-ray fluorescence (XRF), as shown in
Table 1, to calculate the molar ratio of silicon
to aluminum (Si/Al) and sodium to aluminum
(Na/Al). The scanning electron microscope
with energy dispersive spectrometer (SEM/
EDS) was used to characterize the morphology
of initial materials and resultant products, as
shown in Figure 1.