Synthesis and Characterization of Porous Fly Ash-Based Geopolymers Using Si as Foaming Agent

Table 2

Parameters and their variation levels.

Parameters	Level 1	Level 2	Level 3	Level 4
Silicon content (Si% w/w)	0.050	0.085	0.120	0.150
Alkali to aluminum ratio (R/Al)	0.8	1.2	1.6	2.0
Alkali species (Na/(Na + K))	0.00	0.35	0.65	1.00