Mitigating frost heave of a soil stabilized with sisal fiber exposed to freeze-thaw cycles

To embrace sustainable and environmentally friendly practices, sisal fibers have emerged as a green and low-carbon alternative, offering a viable approach for enhancing the physical characteristics of frost-vulnerable soils. In this study, the unconfined compressive strength and freeze-thaw cycle (FTC) tests for soils stabilized with sisal fiber were conducted, and the enhancement mechanism of sisal fibers on soils in cold regions was analyzed. The results showed that as the sisal fiber content raised, the unconfined compressive strength of the soil samples initially increased and then decreased, which reached a peak at 0.9% sisal fiber content. The heat flux in the sisal fiber-reinforced soil samples exhibited a more dramatic variation than that in the soils without adding fibers during the water-ice phase transition stage. The unfrozen water hysteresis in the fiber-reinforced soil samples initially decreased and then increased as the soil temperature decreased. With an increase in the FTCs, the frost heave for sisal fiber-reinforced soil samples occurred, whereas settlement appeared in the soils without adding fibers. The cumulative deformation of sisal fiber-reinforced soil samples was lower than that of the soils without adding fibers. Additionally, the thaw settlement rate was lower than that of frost heave rate for sisal fiber-reinforced soil samples, while the reverse results were occurred for the soils without adding fibers. The addition of sisal fibers established a more robust structural integrity to the soils.