ABSTRACT
Recycling waste materials for barrier system of landfills has more recently been increasingly considered in geotechnical engineering to improve sustainability. Among various geomechanical parameters, hydraulic conductivity is one of the essential factors to be evaluated when designing landfill liners. With such motive, three types of materials were studied in our ongoing research: press filter residue (PFR), cement stabilized clay (CSC) and dry crust clay (DCC). The three recycled materials were compacted in a field pilot project to investigate their applicability as landfill liners. Compacted samples from the pilot project were then cored in tube samplers and transported to the laboratory for hydraulic conductivity measurements. Permeability was measured using oedometer, flexible wall permeameter and triaxial permeability cells. Permeability measurements were made on horizontal and vertical directions to investigate potential permeability anisotropy characteristics at a wide range of consolidation stress levels (15 kPa to 650 kPa). The hydraulic conductivity measured on the samples was in the range of 2×10-7 m/s to 10-1° m/s. For most of the samples, permeability decreased to below 10-9 m/s with increasing stresses, where Norwegian regulations and practice recognises that it is suitable for, liners of landfills containing non-hazardous and hazardous waste. Moreover, the hydraulic conductivity of the materials was anisotropic, and the anisotropy changed with increasing consolidation stresses.
