Pore-size distribution of a compacted silty soil after compaction, saturation, and loading

Soil microstructure is an important feature that controls soil behaviour at the macroscale. This microstructure depends on the sample preparation method and evolves during saturation and loading. This paper investigates the effects of compaction water content, drying techniques adopted prior to performing porosimetry, saturation and loading on the evolution of the microstructure of a silty soil. Mercury intrusion porosimetry is used to obtain the pore-size distribution at different states of soil presenting single and double porosity. It is observed that in presence of aggregates (obtained from a compaction on the dry side of optimum), the bimodal pore-size distribution is not significantly affected by the saturation process at zero stress. This feature of behaviour is quite specific to low plasticity silty soil. Conversely, loading under saturated conditions has a more significant effect on the pore-size distribution. This bimodal distribution converges into a single mode of pore size when the stress is significantly greater than the apparent preconsolidation pressure. The observed experimental results are interpreted in the light of pore-size distribution evolution during saturation and loading.