Decementation, Softening, and Collapse: Changes in Small-Strain Shear Stiffness in k0 Loading

The small-strain stiffness of freshly remolded soils is controlled by the state of stress. Diagenesis and cementation can significantly stiffen soils. However, these effects are lost at relatively low strain levels. Previous experimental results have shown the detrimental and irrecoverable effects of unloading on cementation. This study explores the effect of k0 loading on the small-strain stiffness of cemented specimens, with emphasis on the load-induced collapse and softening of cemented, loose soils. The evolution of collapse and decementation is monitored within an oedometric cell by means of small-strain shear wave propagation. Results highlight the interplay between stress-cementation history and initial void ratio. It is observed that the probability of collapse and decementation softening decreases with the increase in effective confinement at the time of cementation, the extent of cementation, and soil density. Volume collapse is preceded by stiffness loss. At high confinement, the stress-independent small-strain stiffness of initially cemented soils gradually converge to the stress-dependent stiffness that characterizes freshly remolded, uncemented soils.