A Methodology to Determine Water Vapour Diffusion Characteristics of Geomaterials

Water vapour diffusion is a predominant moisture transport mechanism in an unsaturated soil due to the presence of either thermal gradient or concentration gradient. In such soils, as water content decreases, the continuity of liquid films is lost, and as a result, water movement is mainly in the form of water vapour. The knowledge of water vapour migration characteristics of geomaterials is important in the performance evaluation of underground buried services, compacted/geosynthetic clay liners, geothermal energy utilization, thermally enhanced clean-up of contaminated sites and the containment facilities for disposal of high-level nuclear waste. In view of this, the present study describes a methodology to investigate the water vapour diffusion through geomaterials under isothermal conditions. Further, the study evaluates the effect of particle size and compaction state on water vapour diffusion characteristics of the soils.