Influence of soil microstructure on air permeability in compacted clay

This paper describes an experimental study aimed at evaluating the influence of soil microstructure on air permeability in compacted clay. Air measurements, estimated using gas pressure decay method, were carried out for a wide range compaction states. The evolution during wetting and drying paths was also evaluated. results show that, increase as-compacted degree saturation, may either or decrease depending dry density. increases with increasing saturation loose specimens, whereas opposite trend is observed dense specimens. Microstructural analysis, mercury intrusion porosimetry (MIP) tests, shows strong dependency microstructure. behaviour noticed specimens that experienced large variation drying. data indicate mainly controlled by pores display high connectivity. plays dual role which, turn, affects permeability. Denser (dry density ≥ 1·5 Mg/m 3 ) reduction k eff due to expansion clay aggregates saturation. samples ≤1·3 produces enhancement proportion macro pores, thus , as consequence modifications pore size distribution. A threshold value has been identified, above which further causes therefore . new proposal estimating proposed this based determination parameter obtained from MIP data. approach seems capable describing whole spectrum states, including subjected paths.