Synthesis of alkali-activated vitrified bauxite residue for the immobilization of incineration ashes

The processing of burnable radioactive waste produces a variety of incineration ashes, which form a problematic waste stream which needs to be turned into a stable waste form abiding by existing waste acceptance criteria. In the context of an ongoing PhD project, the cementation of incineration ashes in matrices based on vitrified bauxite residue (VBR) is investigated. These matrices can be either cementitious (i.e. based on Portland cement where VBR is used as a supplementary cementitious material) or alkali-activated (i.e. the VBR is used as a precursor which is dissolved by a strongly alkaline solution).

The bachelor student would assist the PhD student in their work on the synthesis of the VBR matrices. Depending on the start of the internship, the bachelor student will synthesize either reference materials, i.e. without ashes, or waste forms including ashes. The work of the bachelor student will contribute to the optimization of the formulations regarding mechanical strength and/or waste loading of the ashes. During synthesis the student will test fresh properties (viscosity, setting time, mini-slump test), while after curing they can test a selection of property materials (water porosity, Fourier Transform Infrared Spectroscopy).