The reinforcement mechanism and effect of potassium silicate solutions in an unsaturated loess soil subjected to saturation

Solutions of potassium silicate (PS) have been applied to reinforce ancient unsaturated earthen structures in arid regions in northwest China in recent years. Some technical challenges in this reinforcement method still require further study. The performance of PS-reinforced loess soil after rainfall is of great concern. This study investigates the permeability and shear strength of PS-reinforced loess soil from the ancient city of Jiaohe upon saturation. Saturated loess specimens reinforced by 3% PS and 7% PS show higher peak shear strength by 90% and 360%, respectively, as compared with unreinforced specimens. The addition of 3% PS and 7% PS reinforcement also results in higher residual shear strength by about 50% and 250%, respectively. These results suggest that PS reinforcement should be effective under saturation conditions due to rainfall. SEM and TEM analysis reveals that the effectiveness of PS reinforcement is related to reticulardense structures in PS-reinforced soil. The structure of PS-reinforced soil results from non-crystalline and crystalline mixtures produced t from the interaction between PS and clay minerals.