Cement-stabilized marine clay under thermal cycling: strength, suction, and microstructure

Abstract This study investigates the influence of realistic summer daily thermal cycles on the mechanical, hydraulic, and microstructural properties of cement-stabilized sensitive marine clay (SMC), a problematic marine soil widely found in Eastern Canada. SMC samples treated with 5% and 20% cement were subjected to two curing regimes: constant temperature (20 °C) and simulated daily thermal cycles, and tested after 1, 3, 7, and 28 days of curing. Unconfined compressive strength (UCS) and secant modulus tests were performed to assess mechanical performance, while matric suction monitoring, thermogravimetric analysis (TG/DTG), and mercury intrusion porosimetry (MIP) were used to evaluate hydration behavior and microstructural evolution. Results show that daily thermal cycles significantly accelerate strength and stiffness development at early curing stages by enhancing cement hydration, leading to finer pore structures and higher matric suction due to rapid self-desiccation. However, a “crossover effect” was observed in TG/DTG results, where prolonged thermal cycling reduced hydration product formation at later stages. MIP results, in contrast, showed continued microstructural densification, likely due to a dilution effect associated with high water-to-cement ratios. These findings provide practical insights for optimizing curing strategies and binder dosages in road and infrastructure projects involving sensitive marine clays under fluctuating thermal conditions.