In cold regions, the performance, safety, and serviceability of engineering facilities overlying on freeze- thaw susceptible soils are being compromised to varying degrees due to the alternate seasonal freezing and thawing cycles (FTCs). FTCs induce temporary and permanent microstructural deterioration of the underlying soils, especially fine-grained soils. In this study, we investigate the shear strength and stiffness behavior of low-compressibility silt subjected to alternate FTCs. Four series (S1 to S4) of unconsolidated undrained triaxial compression tests were performed on moist tamped solid cylindrical soil specimens. The specimens were prepared at four compaction states by changing dry unit weight and moisture content. At each compaction state, unfrozen (normal) specimens and specimens subjected to different number of FTCs were tested at total confining pressures ( 63 ) of 100 kPa, 200 kPa, and 300 kPa. At lower moisture content and increased 63, strain-hardening behavior was more obvious in the stress- strain response. The strain-hardening behavior was subdued with the number of FTCs. Higher moisture content and lower dry unit weight make the silt susceptible to frost action and thaw weakening. Percentage reduction in peak shear strength ranged from 20 to 32% for specimens subjected to 16 FTCs in S1 and S2, 8 FTCs in S3, and 04 FTCs in S4. The reduction in resilient modulus ( MR) with the number of FTCs ranged from 2 to 48% for the four compaction states. The reduction in apparent cohesion value was in the range of 23-64%. After an initial decrease in the range of 16-59%, the angle of internal friction showed a net increase in the range of 8-142%. The current study reveals that low- compressibility silt is susceptible to frost action and thaw weakening. The results show that the S4 with the highest moisture content and void ratio (lowest dry unit weight) aggravates the frost action in the soil.
