Stabilization of clay soil of Lajut Village, Central Lombok District, with a mixture of rice husk ash and quicklime on California Bearing Ratio (CBR) value

Abstract Clay soil bears physical characteristics that are susceptible to changes in high shrinkage growth due to changes in water content, so the bearing capacity is strongly influenced by water content. This study determined the characteristics of clay soil from Lajut Village, Praya Tengah Subdistrict, Central Lombok Regency before and after adding rice husk ash. The stabilization materials consisted of rice husk ash and quicklime, with variations of rice husk ash + quicklime of 4%+4%, 8%+8%, and 12%+12%. Physical and mechanical properties of the clay soil were examined and the results of physical properties testing demonstrated original moisture content of 54.80% and plasticity index of 29.66%. Based on the Proctor standard test, the primary soil contained 32.93% water and 1,292 grams/cm 3 dry weight volume. The variation of 8% rice husk ash and quicklime produced the optimum California Bearing Ratio (CBR) value (22.00%) and optimum CBR soaking variation (7.48%). Conclusively, rice husk ash and quicklime show the capacity to increase CBR value of clay soil.