Unconfined compression tests are normally carried out on lime treated soft clays with variation of the additive content and curing time. These studies were valuable in having a good understanding on the strength of the treated clays. In this paper, some works carried out under triaxial undrained consolidation conditions are presented and discussed within the frame work of state boundary surface and associated stress-strain behavior. The results clearly illustrate the effect of additive content and the curing time in the development of pore pressure and shear strain under undrained condition.