Effect of lime-rice husk ash on geotechnical properties of loess soil in Golestan province, Iran

Abstract Loess soils have always been among the most problematic soils, according to engineers. Due to the sensitivity and vulnerability of this soil type, researchers are constantly looking for different solutions to improve and stabilize this soil using different methods. In the present study, a mixture of lime and rice husk ash (LRHA) was used to modify the loess soil of the Golestan province, Iran. Lime and RHA were mixed in a ratio of 2:4 and with different contents of 2.5, 5, 7.5, 10 and 12.5% of the dry weight of the soil. To study the effect of curing on the strength properties, the samples were cured and tested for 7, 18 and 28 days. Atterberg limits, modified Proctor, unconfined compressive strength (UCS) and scanning electron microscope tests (SEM) were performed. It was found that increasing LRHA content increased the value of UCS at different curing times, such that UCS increased about five times by the addition of 5% LRHA to the loess at the end of 28 days. As the curing time increased, the optimum amount of the additive also decreased. The results showed that combining the soil with LRHA is an effective method for improving and stabilizing loess soil. According to the results of the study, the optimum value of 5% additive is economically and technically recommended.