Effect of rice husk ash on physical properties of soft soil

Rice husk ash (RHA) is a waste material from burning rice husk which is abundant in Vietnam. The utilisation of RHA in soil improvement has been widely investigated. However, the effect of different RHA types on the physical properties of soft soil such as Atterberg limits has not been clarified yet. In this study, two types of RHA obtained from open burning and burning in a furnace will be used to investigate their effects on the physical properties of soft soil such as specific gravity, water content, and the Atterberg limits. The RHA contents from 0 to 15% by the dry weight of soil were used to mix with soft soil. The research results showed that the types of RHA have little effect on the change of water content and the Atterberg limits. Nevertheless, the RHA with low silica content (high carbon content) will result in a higher decrease in specific gravity. Regarding the change in soil particles, the addition of both RHA types can lead to an increase in the silt content of treated soil.