Investigation of the Effect of Lime Treatment on the Soil Water characteristics curve of expansive Soils

The engineering behavior of natural untreated and compacted lime-treated expansive soils, which typically exist in a state of unsaturated condition, can be better-explained using concepts from unsaturated soil mechanics. The soil water characteristics curve (SWCC) is the key unsaturated soil property for obtaining unsaturated soil property functions (USPFs). However, there are limited studies on the effect of lime on the SWCC of lime-treated expansive soils. This study investigated the effect of lime on the SWCC of lime-treated expansive soils. The drying portion of SWCCs for untreated natural soil and lime - treated soil samples with three different lime contents (3 %, 6 % and 9 %) with 7 days of curing were studied. The SWCCs were determined by using pressure plate apparatus in the suction range of 0 – 1400 kPa. The shrinkage curve (SC) was also determined to evaluate the change in volume of the different soil samples. The experimental results indicate that SWCC is affected by lime treatment and there is a change in the SWCC parameters and in the shape and position of SWCC as the percentage of lime is changed. The SWCC of the lime-treated soil samples show a higher rate of desaturation as the lime content increases. The Air Entry Value (AEV) and residual water content of lime-treated soil decreases with increase in percentage of lime and the SWCC shifts towards the left side as the AEV decreases. The differences in AEV obtained from gravimetric- water-content-based SWCC (w-SWCC) and degree-of-saturation-based SWCC (S-SWCC) for the lime-treated soil samples were small when compared to the untreated natural soil sample.Keywords: Air-entry value, Expansive soil, Lime treatment, Shrinkage curve, Soil–water characteristic curve, Unsaturated soil.