Porosity Changes due to Hydration of Compacted Bentonite

As a contribution to the understanding of bentonite hydration, the porosity of two different compacted bentonites with different degrees of saturation was analysed by mercury intrusion porosimetry and X-ray diffraction. The percentage of macropores, as well as the macropore mode, decreased with dry density both in wet and dry samples. Wet samples showed a predominance of microporosity. The basal spacing increased with water content. The porosity distribution for a given water content was not the same for samples hydrated before compaction than for samples saturated under constant volume. In the latter case it clearly evolved over time, the interlayer distance becoming higher.