A laboratory investigation of the mechanical behaviour of a volcanic ash

This paper presents the results of a physical and mechanical characterization of a volcanic ash collected during a recent eruptive episode of Mount Etna. The mineralogy and microstructure of the material are examined by means of X-ray diffractometry and electron scanning microscopy (SEM). Because of their lightweight, highly crushable and compressible nature, they are problematic from engineering and construction viewpoint. The laboratory testing programme consisted of standard drained and undrained triaxial compression tests, one-dimensional compression tests and direct shear tests. Herein, data which highlight particle damage during the one-dimensional compression are presented. Using a dynamic image analysis instrument (QicPic) the changes to particle size distribution and particle shape through breakage are investigated for samples with different initial densities to examine the effects of particle packing on their behaviour. The amount of breakage is quantified comparing the grain size distributions at the beginning and at the end of each test.