Abstract:

Due to the high organic content, strong adsorption capacity and low permeability, dredged soil can be used as a kind of additive to clay liner of landfills. The changes of physico-mechanical properties of the silt clay and the mixed soil (silt mixed with dredged soil) before and after cation adsorption have been investigated. The permeability and shear strength, two basic issues of the quality of clay liner, have also been studied. The hydraulic conductivities of the crude soil and the mixed soil increase with increasing quantity of cation adsorption on the soils. However, the hydraulic conductivities of the mixed soil is less apt to be influenced than that of the silt. After adsorbed with cations, both the frictional angle and the cohesion force of the silt clay and the mixed soils increased at first and then reached a peak, whereas the increases of the cohesion force of the silt clay as well as the frictional angle of the mixed soil were comparatively more. In a word, the addition of dredge to silt could improve the effect of cation adsorption on permeability and strength of soil. SEM photo were conducted to evaluate the changes of microstructure of soils. The relevant impacts were further discussed by means of electrostatic double layer theory.

Key words: adsorption, compacted clay, dredged soil, permeability, strength