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

Table 4

Contribution (%) of the studied parameters on the development of the compressive strength and apparent density.

Parameters	Si content	R/Al	(Na/(Na + K))
Compressive strength	26.9	71.7	1.4
Apparent density	32.0	59.5	8.5