Effects of sequential hydration on water retention and shrinkage of cement-stabilized unsaturated soil

Early-age shrinkage cracking often compromises the durability of infrastructures constructed with cement–stabilized soils (CSS). This study evaluates a sequential hydration (SH) strategy designed to curb shrinkage while sustaining hydraulic response (e.g., degree of saturation) and mechanical performance pertinent to seepage control and serviceability limit-state design. Three hydration paths were examined: OH-100, one-time hydration at 100 % OMC; SH-80 and SH-60, compaction at 80 % and 60 % OMC respectively, followed by second-stage wetting. Soil-water retention curves (SWRCs) were measured under zero-stress and vertical stress using a stress-controllable pressure-plate apparatus and drying–wetting shrinkage was tracked over three cycles for a CSS. The results show that SH significantly reduces early-age free shrinkage while modifying water-retention behavior, hysteresis, and stress-dependent hydraulic response. Among the investigated treatments, SH at 80 % OMC produced the most favorable balance between shrinkage mitigation and hydraulic performance. SEM/EDX analyses suggest that staged hydration promotes pore-throat refinement and changes hydration-product distribution, particularly A-S-H formation. These findings indicate that SH may serve as a construction-stage strategy for reducing shrinkage cracking in cement-treated pavement bases while maintaining adequate hydraulic performance.