摘要：This paper presents details of a study that deal with determination of engineering properties and stabilization mechanism of silt sedimented in Jiangsu when it is treated by a nontraditional additive. Investigations were carried out with respect to the effect of lignin content and curing time on the basic soil properties including compaction characteristics, pH and unconfined compressive strength. In addition, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and Fourier transform infrared resonance were conducted to understand the stabilization mechanism of lignin treated silt. The study reveals that the engineering performance of silt is improved after treatment by lignin. The optimum content for stabilizing this silt is approximately 12%. A more stable soil structure is formed when lignin added into soil after a period of days curing. The changes on microstructure of treated silt are mainly attributed to the reduction of crystalline size and bonding effect of positive charged lignin polymer on soil particles. Hydrolysis, protonation and cation exchange are taken place between lignin and clay mineral and the surface negative charges of clay mineral are reduced by electrostatic charge neutralization, which make the thickness of double-layer reduced. However, there is no new clay mineral formed in the treated silt. A possible stabilization mechanism of lignin treated soil is proposed to provide some guidance for applying nontraditional additives in geotechnical engineering.
