Mechanical and hydraulic properties of MSW incineration slags

Municipal solid waste incineration plants produce considerable amounts of residues; the most part of them consists of incineration slags, which could be used as a construction, draining and stabilizing material in view of landfilling. Laboratory tests were carried out in order to investigate the geotechnical behaviour of four slags, coming from different italian incineration plats. In particular hydraulic and mechanical properties of the slags were evaluated by means of falling-head permeability and multistage consolidated-drained triaxial tests. Testing specimens were reconstructed in laboratory, compacting them with medium and low compaction energies

Numerical Modelling of the Assembly of Big Bags to Optimize Landfill Disposal

The so-called ‘big bags’ are used in landfills to dispose waste material in a sequential manner. In this study, big bags are constituted by geosynthetics and filled with organic waste similar to granular material. The result is an element having a blocky shape and being highly deformable. The process of deployment of big bags for waste disposal in landfills becomes crucial when considering the stability of these assemblies. This paper is intended to focus on the understanding of the mechanisms governing the stability of these assemblies of blocks by means of Distinct Element numerical modelling. To determine the appropriate properties to be assigned to the model, a calibration process was performed by simulating the behaviour of a single big bag undergoing loading and unloading stages. A real scale experimental setup was implemented at the site to test the behaviour of the block by superimposing a concrete cubic weight to a big-bag and measuring the deformations at different time intervals during loading and unloading. The numerical analyses showed to be appropriate to reproduce the behaviour of the big bag at the single block scale and were adopted to study the stability of the assembly in a variety of geometrical layouts. The work performed allowed the definition of the arrangement that guarantees the stability conditions of the assembly