USE OF SILT-CLAY MIXTURES IN MSW LANDFILLS COVER SYSTEMS

摘要

Grumolo delle Abbadesse (Vicenza, Italy) MSW landfill involves the reuse on its cover system of sandy-silty soil produced by the wide pits excavation. Sandy silt is naturally suitable for use as a mineral barrier of a capping landfill at its natural state, because its k is <10~(-8) m/s. It seemed to be proper to consider further soil properties besides permeability. Low plasticity turnes into poor ductility, difficulty of compaction and absence of self-healing capability against cracks caused by high differential settlements of wastes. In previous studies we used both sodium bentonite or natural clays for increasing the plasticity of the silty soil. The significant costs of sodium bentonite has forced us to favor the choice of the natural clays as additive. Clays, however, were not naturally characterized by a structure suitable for the in situ mixing process, because they had variable moisture content and clods aggregations. The core issue and the innovative aspect of this paper consist to identify the proper pre-treatment operations on the clay and a mechanical procedure for an effective mixing.