This paper assesses the effect of freeze-thaw properties of compacted fly ash specimens likely to affect its use as fill material, on the basis of laboratory investigations conducted on Soma-B Thermal Power Plant ashes in western Turkey. Test specimens were subjected to compaction. Changes in strength with curing time and freeze-thaw cycles are measured using unconfined compression tests, and increases in strength with curing time and the number of freeze-thaw cycles were observed. The findings suggest that compacted Soma-B fly ash could serve as fill material, particularly over weak subgrades with no negative environmental effects, provided that the degree of saturation of the compacted fly ash embankment is at a specific value.