Changes of small strain shear modulus and suction for a lime-treated silt during curing

To clarify the mechanism of stiffness change by pozzolanic reaction for lime-stabilised soils during curing, it is essential to avoid the effect of water evaporation in this process. In this study, changes of small strain shear modulus G_max and total suction of a lime-treated silt during curing were investigated, with water content kept constant to avoid the effect of water loss. The soil samples were prepared with 2% lime, and then compacted dry of optimum (17%) and wet of optimum (22%). The G_max values were determined at various curing times using bender elements and the suction was measured using a hygrometer WP4. Results show that a two-phase development of G_max occurs for the lime-treated samples. The G_max increases slowly in the first phase, corresponding to the flocculation process, but then G_max starts to increase significantly in the second phase owing to the substantial cementitious compounds produced through pozzolanic reaction. Interestingly, the suction changes follow the same two-phase pattern, suggesting that the production of cementitious compounds increases the soil stiffness; it also modifies the soil microstructure, leading to soil water redistribution and thus changes in suction.