Moisture transport in unsaturated cementitious materials exposed to different initial saturation levels (20–80%) and sodium sulfate concentrations (0–10%) was investigated through experiments and numerical modelling.The effects of water-cement ratio (w/c), initial saturation,and sulfate attack on pore structure and capillary water absorption were evaluated by adsorption-desorption tests,mercury intrusion porosimetry (MIP),capillary water absorption tests,and numerical simulation. The results show that pore structure governs moisture transport behavior.A higher w/c leads to higher equilibrium saturation because of improved pore connectivity, whereas lower initial saturation results in a higher capillary water absorption coefficient and a longer unsaturated transport path. Sulfate attack exhibits a clear concentration-dependent effect:low sulfate concentrations (2.5–5%) enhance moisture transport by locally improving pore connectivity,while high concentrations (>7.5%) inhibit transport because excessive reaction products block pores.Findings from this study offer a theoretical foundation for cementitious material durability design and life prediction in sulfate-enriched settings.
Wen et al. (2026) studied this question.