Characterization of geomechanical and hydraulic properties of non-wettable sands

Wildfire, diagenesis, and organic contamination often induce the non-wettability in soils which in turn dominate physico-mechanical behaviours and control the contact angle and capillary pressure. This study presents the characterization of hydraulic and geomechanical properties of non-wettable sands using artificially synthesized hydrophobic sands. The critical hydrostatic pressure that initiates the fluid intrusion into dry hydrophobic sands is measured to estimate permeation boundary. Hydraulic conductivity values of both hydrophilic and hydrophobic sands under fully saturated condition are examined to evaluate the drag force effect. For geomechanical study, a series of constant water content compression tests are performed to assess the mechanical behavior on a reconstituted specimen of unsaturated non-wettable sands. The stress-strain relationships according to the degree of saturation under confining pressure condition are observed so as to derive the suction stresses. Results highlight that the surface modification at nano-scale determine the spatial configuration of water phase in pore space and its impact on fluid flow and strength with varying degree of saturation prevails.