Experimental Investigation of the Dynamic Characteristics of Treated Silt Using Lignin: Case Study of Yellow River Flood Basin

Silt is widely distributed in North China Plain, especially in the Yellow River flood basin. Unfortunately, untreated silt cannot be directly used as a subgrade filler. Therefore, it is of great practical significance to explore the reinforcement of silt in the Yellow River flood basin. To solve this problem, the dynamic characteristics of silt added with different proportions of lignin were studied. The correlation among lignin content, curing time, dynamic shear modulus, and damping ratio of the improved soil was tested. The results showed that the dynamic strength and shear modulus can be effectively improved by adding lignin. The optimal lignin content for the dynamic strength and shear modulus was 5%. To understand the microscopic mechanism of lignin-treated silt, scanning electron microscopy (SEM) was performed on lignin samples. The SEM results showed that with an increase in lignin content, a certain amount of cementitious materials was formed in the soil. These cementitious materials wrap up the soil particles and connect the fine soil particles to form larger aggregates. The research results can provide a reference to further improve the physical and mechanical properties of the silt in the Yellow River flood basin, and this study is instructive.