Mechanisms of concentration control alkali activated fly ash stabilized saline soil in seasonally frozen regions

In the framework of sustainable development and environmental preservation, this research aims to improve the stability and frost resistance of sulfate saline soil by utilizing industrial solid waste. Geopolymer materials containing fly ash (FA) activated by different NaOH concentrations were studied for study on stabilized soil with saline soil, with NaOH concentrations used ranged from 0.1 to 0.9. This study investigates the impact of the molar concentration of NaOH and the number of freeze-thaw cycles on the microstructure and strength of stabilized soil incorporating FA geopolymer. The XRD, FTIR, and TG studies of NaOH-excited FA stabilized soil revealed that the FA gel material grew with increasing concentration. The strength and frost resistance of stabilized soil increased and then declined as NaOH concentration increased, with an optimum excitation concentration of 0.5 M. After 28 days of curing at 20 °C, its UCS and splitting strength were 7.18 MPa and 1.89 MPa, respectively. The residual values of UCS and splitting strength after 5 freeze-thaw cycles (12 hours of freezing followed by 12 hours of thawing at +20 °C) at the optimal concentration were 46.35% and 39.92%, respectively.