Role of Cementation and Suction in the Swelling Behavior of Lime-Treated Expansive Soils

When cured in the field, unsaturated lime-treated expansive soils will undergo concurrent development of lime cementation and suction stress. This study aims to assess the relative roles of lime cementation and suction stress in the swelling potential of two lime-treated expansive soils cured under different curing environments. To this end, a series of tests were conducted to evaluate the one-dimensional swelling potential of statically compacted lime-treated expansive soils cured under controlled curing (CC), in-laboratory curing (ILC), and field-simulated curing (FSC) conditions. The characteristics of curing environment in terms of temperature, relative humidity, and imposed total suction are presented. For each curing environment, the swelling potential and total suction of lime-treated expansive soils as a function of lime content (2, 4, and 6%) and curing period (7, 14, and 28days) were measured. The results reveal that curing environment had a significant effect on the swelling potential of the lime-treated soils considered. Different trends in the variation of swelling potential with curing period were observed to depend on soil type, lime content, and curing conditions. These swelling potential trends were interpreted in view of two mechanisms, namely, development of lime cementation bonds and suction stress emergence in specimens caused by desiccation, especially under ILC and FSC environments. Finally, a rational approach was proposed to visualize the effects of suction and lime cementation on swelling behavior of lime-treated expansive soils. This approach may be used to define the cementation-suction equilibrium stress, which can be used to quantify the magnitude of lime cementation bonds.