Enhancing Resilience of Silty Clay Soils with Basalt Fibers: Evaluating Geotechnical Performance under Freeze–Thaw Cycles and Temperature Variations

Abstract Freeze–thaw (F-T) cycles critically degrade the mechanical performance of fine-grained soils, challenging infrastructure resilience in cold regions. Silty clayey soils in northern Quebec, which have high frost susceptibility and water retention, are particularly vulnerable. This study explored the potential of basalt-fiber reinforcement to enhance the thermomechanical behavior of such soils. Laboratory tests, including unconfined compressive strength (UCS), double-punch tensile strength (DPT), and temperature-controlled triaxial compression, were performed on samples with various fiber contents (0%–1%) and lengths (3, 6, and 12 mm), both before and after multiple F-T cycles. Results show that fiber inclusion significantly improves strength and deformation resistance. Optimal reinforcement (0.8% fiber content, and 12-mm length) increased UCS and DPT by 32% and 194%, respectively. Enhanced cohesion and elastic modulus under F-T conditions further confirm the effectiveness of reinforcement, especially under moderate confining pressures. However, shorter or poorly proportioned fibers diminished these benefits, emphasizing the importance of optimized mix design. Overall, the use of basalt fiber is a sustainable and cost-effective strategy to improve the durability of fine-grained soils in cold climates, with direct applications for roads, embankments, and foundations.