Performance of Compacted and Stabilized Clay with Cement, Peat Ash and Silica Sand

An experimental investigation was carried out to evaluate the performance of compacted clay stabilized with cement, peat ash and silica sand. A significant soil improvement can be achieved through the compaction and stabilization of clay. The main objective of this study is to evaluate shear strength characteristics, CBR and unconfined compression behavior of untreated and stabilized soil with cement, peat ash and silica sand. The soil specimens were tested at optimum moisture content and maximum dry density. Based on the results obtained from standard Proctor compaction test, the ideal mix design was further applied for direct shear, unconfined compression and CBR tests. Both untreated and stabilized soil specimens were subjected to 10.90 kPa, 21.80 kPa, 43.60 kPa and 87.20 kPa vertical effective stresses of direct shear tests. The microstructure analysis of the stabilized soil was examined using scanning electron microscope test. Results indicate that there is a significant influence of cement addition to the strength of the stabilized soil. It was found that the unconfined compressive strength of the stabilized soil specimen with 2% partial replacement of cement with peat ash is almost 1.7-fold greater than that of the untreated soil specimen. The type of failure behavior of the test specimens varied greatly. The untreated soil specimen exhibited ductile behavior in failure under unconfined compression test; whereas, stabilized soil specimen with the binder composition of cement 18%, peat ash 2% and silica sand 5% posed brittle behavior. Highlights ► Peat ash dosage affected compaction properties of the soil specimen. ►Ordinary Portland cement was partially substituted with peat ash. ►Binder composition of cement 18%, peat ash 2% and silica sand 5% improved shear strength parameters, CBR and unconfined compressive strength of the soil specimen.