One-dimensional compression of volcanic ash of Mount Etna

This paper presents the results of both a physical and mechanical characterization of a volcanic ash, the Etna Sand, collected during a recent eruptive event of Mount Etna. The interest for this material, commonly found in the areas surrounding the volcano, stems from its compressibility and the crushable nature of the sand grains. For both these aspects, Etna Sand is a problematic material from an engineering and construction viewpoint. The physical and mechanical characterization involved X-ray diffractometry and electron scanning microscopy (SEM), to analyze mineralogy and microstructure, and one-dimensional compression tests carried out on both wet and dry soil specimens characterized by different initial densities. In order to examine the effects of the loading on the evolution of the micro-structure, the authors analyzed by means of the Qicpic apparatus both the particle size distribution and the particle shape before and after the tests. When the specimen is tested at vertical pressures larger than 1MPa the grain crushing becomes evident, whereas for values larger than 10MPa the grain crushing process seems to be progressively inhibited.