2013 Volume 69 Issue 3 Pages 378-385
Understanding the relationship among water saturation, water matric potential, and air permeability is important for accurately simulating the behavior of toxic gases at the polluted site and optimizing remediation technologies. In this study, air permeability (ka) was measured on sands with different particle sizes and shapes during drying and wetting cycles. The hysteresis in soil-water retention highly affected gas transport, showing higher ka for the wetting processes than for the drying processes at the same air content for all sand samples. This suggests that the existence of more continuous air-filled pore networks for the wetting processes enhanced advective gas transport. A power-law type ka model was applied to the measured data, demonstrating a clear relation between the pore network tortuosity factor in the ka model and model parameters for describing water retention characteristics. In addition, it is indicated that for sands with rough particle shape the continuity in larger-pore network is obstructed by the soil water filled in smaller pores as compared to sands with round shape.