Strength and Durability Performance of Sandy Loam Reinforced with Xanthan Gum and Biochar

The changing climate raised more concerns about the durability of aged slopes and embankments due to the increased frequency of extreme rainfall events. Recently, there has been a growing interest in the utilization of biopolymer as a biomediated soil improvement method. However, challenges, such as, strength loss due to exposure to adverse environmental conditions and limitations on the suitability of soils for effective treatment, can be problematic in practice. Therefore, this study introduces an innovative approach by combining biopolymer with another eco-friendly material, biochar. The erodibility of the reinforced soil was examined through both wetting and drying tests and slope-rainfall simulation tests with the consideration of different rainfall intensities and slope inclinations. The findings suggest that cyclic wetting and drying conditions can lead to a progressive degradation (decrease in strength) of soils reinforced with biopolymer, starting from the initial cycle. Conversely, incorporating biochar into the biopolymer-reinforced soils successfully postponed this decline in both compressive and shear strength, prolonging the soil’s resilience by two to three cycles. In addition, soil slopes reinforced with the combined treatment exhibited reduced soil runoff and increased durability under both light and heavy rainfall compared to slopes reinforced with either biopolymer or biochar alone. The findings of this study provide an innovative method for controlling soil erosion on sandy soil, suggesting its potential application in slope stabilization and restoration.