Landfill sealing potentials of bottom ashes of sludge cakes

The main objective of this study is to determine if bottom ashes of dried sludge cakes (SCbash) could be used as landfill cover or liner, a function which is normally performed with clay. Laboratory tests were performed to determine its particle size distribution, Atterberg limits, compaction characteristics, hydraulic conductivity, and shear strength parameters. The effects of desiccation and freeze-thaw on the hydraulic conductivity of SCbash were also examined. The results of this investigation proved that properly compacted and stabilized SCbash has the required properties to be used in landfill covers or Liners. The SCbash can be compacted into a dense mass with a low hydraulic conductivity of the order of 1.15x10(-7) m/s. The compacted SCbash showed also a good resistance to the increase in hydraulic conductivity caused by desiccation and freeze-thaw as compared to other compacted clays. The results also indicated that the compacted SCbash has greater shear strength as typically expected for compacted clay, and therefore is likely to remain stable on a typical landfill slope designed and based on clay shear strength. (C) 1998 Elsevier Science B.V. All rights reserved.