Mellowing and anisotropy induced by wetting of moulded soil samples

Disks of seven soils were prepared by moulding the soils at water contents in excess of their plastic limits and by drying. The disks were placed on edge on sintered glass funnels, were wetted from an arbitrary point on their circumference and were then dried isotropically. Disks that had been wetted were weaker than control disks that had not been wetted. For some soils there is a water potential, termed the critical mellowing potential, in excess of which little or no mellowing occurs. For three of the soils studied the mellowing occurred to different extents in different directions. Anisotropic mellowing was investigated as a function of the potential of the source of water causing wetting. Results from multiple wettings of disks indicate that anisotropic mellowing may lead to equilibrium states for a number of soil physical properties including structure and strength.