Stabilization of peat soil using lime as a stabilizer

Peat geotechnical properties such as low shear strength, high organic matter, low bearing capacity and high compressibility make it been regarded as difficult soil. Peat soil is considered by geotechnical engineers as an unfavourable soil for construction. It has covered approximately twenty-three (23) million hectares in South-East Asia with about three (3) million hectares or 8% of the total area in Malaysia. Peat soil has been regarded as problematic soil that poses significant threat to roads and building foundations stability due to its unique characteristics of high compressibility, low shear strength and consolidation settlements even when subjected to a moderate load.
Because of these geotechnical problems of peat soil, improvement mechanism is needed if peat soil is to be used as a soil foundation of a civil structure. Several methods of soil stabilization such as preloading with surcharge, sand column and corduroy among others have been tried by geotechnical engineers to improve peat behaviour. However, such methods were found uneconomical in term of time constraint. Therefore, lime has been taken as a choice for stabilization of peat soil in this paper. Lime material chosen for this research project was provided in Universiti Teknologi Petronas (UTP) laboratory. Eades and Grim test was conducted to determine the optimum percentage of lime that can be mixed with peat soil to provide optimum strength. Lime was mixed with peat soil in different eight (8) percentages: 10%, 12%, 14%, 16%, 18%, 20%, 22% and 24% respectively. The extruded samples were cured for a period of 7 and 14 days. After those respective curing periods, Unconfined compression test (UCT) was conducted on all samples to determine lime impact on peat properties in term of strength increase.
Having analyzed the laboratory test results, it was noticed that 16% lime provided the optimum lime percentage for stabilization of peat samples. An increment in the strength of peat specimens was noticed though the highest strength of 149.3kPa was realized with sample mixed with 14% lime and cured for 14 days. Therefore, lime can stabilize and improve the engineering properties of peat soil mainly strength and pH. Generally, unconfined compression test (UCT) indicates that, peat soil gained strength due to different lime percentages added.