Performance of Molasses-Stabilized Clayey Soil Subjected to Freeze–Thaw Cycles

Nowadays, alternative cost-effective and environmentally friendly waste materials have gained popularity over conventional chemical additives for the stabilization of weak soil in seasonal freeze–thaw (FT) areas. Molasses, a byproduct of sugar production, is utilized in various sectors; however, there are no studies in the literature concerning the use of molasses in the stabilization of clayey soil under FT cycles. To address this aim, in this study, a series of unconfined compressive strength (UCS) tests were conducted on both unstabilized and stabilized samples with molasses ratios ranging from 4% to 14%, subjected to 0, 5, 10, and 15 FT cycles following 7 and 28 days of curing. The assessment focused on the stress–strain (σ-ε) responses, unconfined compressive strength (qu), failure strain (εf), secant modulus (E50), and failure mode. The results demonstrated that maximum performances appeared with 10% molasses ratios, showing a 1.39–2.62-fold increase in the qu values. As the curing period increased, the qu and E50 values increased significantly, while the εf values exhibited a diminishing trend. It was also observed that the FT cycles caused a dramatic reduction in the shear strength of unstabilized samples, ranging from approximately 42% to 69%; however, molasses-stabilized samples demonstrated higher resistance. Furthermore, XRD, SEM, and EDX analyses were carried out to investigate the mineralogical, microstructural, and chemical behaviors. Finally, an empirical equation was proposed to predict the qu of molasses-stabilized soil subjected to FT cycles.