Swelling behaviour and microstructure of biochar bentonite

Biochar bentonite is a potential candidate as a porous layer for nuclear waste repositories. It would provide an ideal niche for bacteria that could feed on sulfate from the host rock and hydrogen from the corroding canisters. In this study, the influence of biochar amendment on the swelling properties of bentonite at different densities has been examined through swelling experiments. Scanning electron microscopy (SEM) images were used to study the surface microscopic morphology of biochar bentonite samples. On the basis of the SEM results, the fractal dimension representing the microstructure of biochar bentonite was determined. The relationship between fractal dimension and the maximum swelling pressure was discussed to reveal the correlation between the microstructure and the variation of mechanical properties for biochar bentonite.