Preliminary investigations into the use of secondary waste minerals as a novel cementitious landfill liner

When cementitious materials are used for the containment of waste they act in two different, and sometimes conflicting, ways. The first is physical and the second is chemical containment in which the water passing through the barrier is buffered to high pH thereby substantially reducing the solubility of many harmful species and promoting sorption onto the matrix. Chemical barriers have been extensively researched for nuclear waste containment and this paper reports on the development of chemical barriers for the non-nuclear waste management. It focuses on the ability of a cementitious barrier to chemically condition liquid leachates, neutralising organic acids and reducing the solubility of priority pollutants. This is similar to the way in which cement suppresses actinide leaching in the disposal of nuclear wastes. In this paper, the results of an extensive preliminary investigation into potential mixes using various mineral wastes are presented and some of the measured properties are compared with those, which are required for a multi-layer barrier. The results indicate that many of these mixes are well suited to this application.