Novel Four-Season Durability Methods for Cement-Stabilized Clays

The durability of stabilized subgrades is the backbone for ensuring pavement’s longevity. Its realistic evaluation is the key to accurate prediction of a pavement’s performance, aiding in the planning of maintenance and rehabilitation. Current ASTM standards for durability assessment of cement-treated soils discuss wetting–drying (WD) and freezing–thawing (FT) separately (in ASTM D559 and ASTM D560, respectively) and do not account for sequential interactions between moisture and temperature fluctuations. With weather patterns becoming more complex, most regions have already started experiencing all four seasons with varying intensities and frequencies. This makes the need for coupled durability assessments highly relevant to mimic the sequential interactions between environmental stresses induced by all four seasons. This paper thus presents two novel coupled durability methods, namely, wetting-drying-freezing-thawing (WDFT) and freezing-thawing-wetting-drying (FTWD), developed by a sequential combination of the existing ASTM standards for WD and FT. Low-plasticity clay specimens stabilized with two stabilizers, ordinary Portland cement (OPC) and Portland limestone cement (PLC), were considered for the coupled durability studies. The influence of the WDFT and FTWD cycles (0, 3, 7, and 10) on the performance of stabilized soils is determined through conventional volumetric and mass measurements. Additionally, rigorous engineering strength evaluations, including the unconfined compressive strength and resilient modulus, were employed, with pavement applications as the primary focus. Findings revealed that the sequence of environmental stressors greatly influences the performance, with WDFT being more detrimental by causing rapid volumetric changes and faster stiffness degradation in both OPC and PLC-stabilized soils, the effect being more pronounced in the latter case.