Testing of mineral liners for landfills in the cold climate

The current landfilling requires use of low-permeability hydraulic barriers to limit emissions of polluted water into the environment, and to isolate the waste fill from the ground. These barrier structures consist of drainage layers, mineral liners, filter layers and membranes, the purpose of which is to ensure the isolation in short and long term, and to protect the structure from defects. When installed in cold climate, freezing and thawing of the mineral liner may cause internal compression of the clay, resulting in fissuring and increase of hydraulic conductivity of the material due to freezing stresses. This risk is well known from earlier for normal clays (e.g. illites and caolinites), but the stability of bentonite in freeze-thaw has been less tested. This study showed that the liners should be designed so that they are stable, if they are exposed significant freeze-thaw. In the testing, the frost susceptibility of the mixture should be controlled, as well as the increase of hydraulic conductivity after freeze-thaw should be determined. By this means, the acceptability of the liner material can be properly ensured.