Grading evolution of an artificial granular material from medium to high stress under one-dimensional compression

This contribution presents the results of an experimental investigation of the mechanical behaviour of granular materials with crushable grains under one-dimensional compression at medium to high stress. The material used for the experimental work is a Light Expanded Clay Aggregate (LECA) whose grains break at relatively low stress. Reconstituted samples were prepared with different initial grain size distributions and their evolution observed under one-dimensional compression. The grain size distributions before and after testing were used to calibrate a bimodal model obtained from the superposition of two Weibull functions. The observed evolution of the micro and macro diameters on loading are linked to the characteristics of the one-dimensional compressibility curve obtained under displacement controlled conditions, such as its shape and two characteristic stress values, namely the pre-consolidation stress and the stress corresponding to the point of inflection.