Characterization of two natural zeolites for geotechnical and geoenvironmental applications

This paper reports the findings of experimental studies on two natural zeolitic soils. Engineering properties (e.g., grain size, specific gravity, compressibility, hydraulic conductivity, swelling behavior and shear strength) were determined in order to assess their suitability for geotechnical and geoenvironmental applications. The two zeolite-rich tuff samples investigated were mainly composed of clinoptilolite. The results show that the cation exchange capacities are 60.5 and 57.2 mEq/100 g, which are below the theoretical reported values. Compression index values obtained reveal that the zeolitic soils are not highly compressible. The modified free swell indexes of the zeolitic samples are around 2.0, suggesting that they have low swelling potential. The drained residual friction angles indicate that the zeolitic soils have relatively high internal friction angles (34° and 36.5° for Z-1 and Z-2, respectively). Based on the results obtained, it was concluded that zeolites are mechanically stable materials that are suitable for embankment materials and landfill liner applications.

Research highlights
► Because of their low compressibility and high shear strength, zeolites are mechanically stable materials.
► The drained internal friction angles are 34° and 36.5° for Z-1 and Z-2, respectively.
► The obtained cation exchange capacities of the samples are below the theoretical reported values.