Soil water characteristic curve (SWCC) of lime-laterite stabilised soil as a lining-system design

Leachate is produced from the infiltration of rainwater through landfill that contaminates the groundwater with some dissolved, suspended particles such as heavy metals and microplastic. Since this issue will endanger human health and pollute the environment, a clay liner is considered to mitigate significant leakage of leachate from a landfill liner system. However, a conventional lining system, geosynthetic clay liner (GCL), has a high possibility for degradation due to some pathogen that might catalyse the hydrolysis of polyester of geosynthetic material. In contrast, compacted clay liners (CCL) have an instability issue due to swelling as well as shrinkage. Thus, lime-laterite stabilised soil has been chosen to test its compatibility to be used as a lining system. Past researchers have stated that adding an effective lime percentage that produces a pH of 12 is one of the mechanisms that can significantly decrease the pathogen in the leachate and improve the absorption of heavy metal ions by the lime-laterite soil. Therefore, the hydromechanical behaviour of laterite soil under unsaturated soil with the treatment of quicklime can be analysed by conducting a soil water characteristic curve (SWCC). This study will be applied as a lining system that acts as a hydraulic barrier that prevents the permeation of leachate. In the geotechnical laboratory, the soil sample was analysed with the pressure plate testing equipment. For this study, lime dosages of 3%, 5%, 7%, and 9% by weight with seven days (7) of optimum curing are applied for soil stabilisation. Fredlund and Xing (1994) and Van Genutchen (1980) models are used to developing the SWCC curve-fitting graph with a suction range between 0.1 kPa and 1,000 MPa. The finding of this study can summarise that increment of quicklime addition can drop the volumetric water content, thus risen the air entry value (AEV). In conclusion, overall results show that the water-holding capacity of untreated and treated laterite soil decreases with increasing lime content. This initial finding shows insights into the possibility of treated soil being used in the landfill using 5% of lime laterite stabilised soil as the best design in terms of SWCC, thus solving the leachate permeation problem.