Utilization of Bauxite Residue as a Liner: Permeability Improvement Using Additives

The results of a laboratory investigation for the reduction of bauxite residue’s permeability, when mixed with certain additives, are presented and discussed in the current work. Based on bauxite residue, nine mixtures were created using fly ash, bentonite, and cement, in 5, 10, and 15% by weight. According to the performed standard Proctor compaction tests and 1D consolidation tests, the addition of 10% and 15% of cement, 10% and 15% of bentonite, and 15% of fly ash, results in permeability less than 10 –7 cm/s, which is the limit according to standards for barriers and impermeable liners in landfill sites. The reduction of permeability takes place even though the examined additives are coarser than the bauxite residue itself, i.e. the mechanism of permeability’s reduction is not due to granulometry.