In this study, the strength behavior and stiffness characteristics of cement-treated fine-grained sandy soils (CTS) reinforced by recycled DTY nylon fibers (CTSF) under the effect of freeze–thaw cycles have been investigated. Cylindrical specimens of sandy soil with cement stabilizer and fiber reinforcement with a diameter of 3.6 cm and a height of 8 cm were made. Three different weight percentages of cement contents including 2%, 4% and 6% and three weight percentages of fiber contents including 0%, 0.5% and 1% have been used for this purpose. Several stress–strain curves obtained from UCS tests are presented to evaluate the effects of 0, 1, 2 and 3 complete freeze–thaw cycles on the CTS and CTSF specimen behaviors. The results of this study show that the increase in fibers reduces the stiffness of the samples under the effect of freeze–thaw cycles. Increasing the percentage of fiber contents also increases the strains corresponding to the peak and residual strength of the specimens. Of course, the relationship between fiber content and fiber length on the strength and stiffness characteristics of the samples is inverse to each other.
