Bulk density, porosity and volume expansion of foam samples
Table 3 illustrates the volume of expansion, bulk density and porosity
of each sample. It can be seen that the volume expansion increases
with the amount of sodium silicate. Highest volume expansion was
attained when the amount of sodium silicate was 55 wt.% for BA40
ash plus the silica network formed from sodiumsilicate solution. Another
prominent new phase appeared at around 28° (2θ angle)which is anorthite
and albite, formed by the sodium and calcium alumino-silicates
and is an indication of geopolymerization reaction taken place; as it is
produced during geopolymerization [20,21]. More in particular, it was
difficult to make a doubtless identification of minor crystalline phases
due to high number of broad, small XRD peaks collected in the
measurement.