Study on unsaturated mechanical properties of lignin-lime improved silt

Abstract

Industrial by-product lignin is a kind of polymer organic matter that can be applied to the improvement of subgrade soils. Based on the lignin-lime composite modifier blending ratio recommended by the unconfined compressive strength test, the soil-water characteristic curve and unsaturated shear strength of the lignin-lime improved Yellow River alluvial silt were studied through a series of experiments. The microstructure of the improved silt was observed by scanning electron microscopy (SEM). The test results show that: after the improvement of lignin-lime, the cohesion of the improved silt increases exponentially with the decrease of saturation, while the internal friction angle does not change much. With the decrease of saturation, the strain softening phenomenon of the improved silt is intensified and the dilatancy is increased. Compared with pure silt, the lignin-lime modifier fills the pores between the soil particles, resulting in a bond between the loose particles and an increase in strength.