Analysis of clay improvement as subgrade using Palm Oil Fuel Ash (Pofa)

Abstract

Road construction on clay soils often causes problems, because clay have a low bearing capacity and high swelling shrinkage values. Damage to roads on soft clay cannot be avoided; therefore, soil improvement is necessary. Soil stabilization is one of the efforts to improve soil properties, and the aim is to increase the bearing capacity of the soil. So far, the stabilizing materials commonly used for soil improvement are cement and lime. In study, oil shell waste in the form of palm oil fuel ash (pofa) will be used as a stabilizing agent. Pofa is one of the industrial wastes that contain a high percentage of silica (Si). The high silica (Si) content is beneficial for reducing the shrinkage properties of clay soils. Pofa ash content used in the study was 4%, 8%, 12%, 16%, and 20% of the total weight soil. The curing time of the sample was seven days with unsoaked and soaked (four days) conditions. The results of this study indicate that mixing pofa ash can increase CBR value and decrease the swelling value of clay.