Abstract

Cut-off walls are in-situ vertical barriers constructed in order to enclose an area of contaminated ground. These walls have very low permeability to control the groundwater flow into or out of these confined sites. The use of cut-off walls made from cement-bentonite slurry has become more widespread in the last two decades in the UK, Europe and Japan. Hence, there is a need to investigate their long term performance using field monitoring as well as laboratory testing. This research has thus been conducted on 11 year old field cut-off wall material along with freshly prepared laboratory samples to study their permeability, strength – deformation and durability properties.

This presentation will mainly cover four aspects of research, namely the permeability and UCS (unconfined compressive strength) laboratory test; in-situ test; triaxial strength test; and durability characteristics. Furthermore, various parameters such as aging, contaminant exposure, mixing of surrounding contaminated soil, depth of wall, ground water fluctuations and weathering actions, which can affect the performance of these containment walls will be identified in this presentation. By taking into account the influence of the above mentioned parameters, the design and long-term performance of cement-bentonite containment systems could be improved.