Collapsibility potential of gypseous soil stabilized with fly ash geopolymer; characterization and assessment

This study focused on effects of intrinsic sulfate in gypseous soil on its collapsibility potential when stabilized with fly ash geopolymer binder. Accordingly, compression and collapsibility tests were performed on the binder and the stabilized soil, respectively. XRD, TGA, and SEM/EDX tests were also conducted to trace changes due to geopolymerization and sulfate attack before and after exposure at different ages of up to 90 days. The results showed the formation of geopolymer gel (A-S-H) with higher strength and more sulfate resistance than Portland cement paste in binder. Furthermore, incorporation of KOH (12 M) activated fly ash in gypseous soil recorded the lowest collapsible potential and coefficient of permeability at 90 days of exposure.