Improving the impermeability and mechanical properties of the Yellow River sediment with polymer gels

Abstract

Natural clay is the most common material used for the veneer cover soil in solid waste landfill because of its good impermeability and mechanical stability. However, it is often difficult to obtain in the arid regions of northern China and an alternative material is urgently needed. This study utilized polyanionic cellulose (PAC) to modify the dredged sediment from the Yellow River (DSYR) to replace the clay used as the veneer cover soil in solid waste landfills. Some engineering properties of PAC-modified dredged sediment (PMDS), including compaction, permeability, shear strength, and drying shrinkage, were investigated by considering the factors of PAC dosage and compaction degree (CD). Microscopic tests were conducted to analyze the improvement mechanism of DSYR engineering properties by PAC modification. The results indicated that the hydraulic conductivity of PMDS decreased obviously with the PAC dosage or compaction degree. The addition of PAC significantly improved the shear strength of DSYR, along with an increase in cohesion but a decrease in the internal friction angle. During drying, there was no apparent horizontal displacement for PMDS, and the vertical displacement was less than 0.17 mm. Microscopic tests revealed that the dosage of PAC and compaction degree mainly affected the contact and pore distribution characteristics between soil particles, thereby changing the impermeability and mechanical properties of DSYR.

Keywords

• Polyanionic cellulose
• Dredged sediment
• Hydraulic conductivity
• Shear strength
• Microstructure