Water Retention and Compressibility of a Lime-Treated, High Plasticity Clay

The paper presents a laboratory investigation, which quantified the beneficial effect of lime on the water retention, compressibility and overall volume changes of a high plasticity clay (London Clay). The study comprised oedometer testing (including suction controlled testing), shrinkage tests, and filter paper testing to determine the soil water retention curves of the drying soils. The latter tests showed that the shallow-mixed lime-treated soils are likely to be partially saturated in situ depending on the environmental conditions; thus, unsaturated soil mechanics concepts are applicable for the description of their behaviour. The oedometer results quantified the marked decrease in the swelling and compressibility of the lime-treated soil compared to the untreated clay and the increase in the vertical effective yield stress (due to suction and cementation bonding). The lime enabled the soil to maintain a more open structure with respect to the untreated soil throughout the compression process, and appears to be the main factor influencing the compressibility of the unsaturated lime-treated soil (rather than suction) for the ranges of suction tested.