Structural characterization of unsaturated aggregated soil

Despite the recent experimental studies of soil structure, a comprehensive understanding of the macroscopic response of a soil in relation to its structure has not yet been achieved. This lack of understanding reveals the need for further assessments of soil structure and its evolution under loading. In this work, the structure of an aggregated soil under various conditions of saturation and mechanical loading is studied. We also compare the aggregated soil structure, which shows a double porous fabric, with that of the same soil when reconstituted. The experimental methods selected for this study are a combination of mercury intrusion porosimetry (MIP), environmental scanning electron microscopy (ESEM), and neutron computed tomography (CT). Using MIP and ESEM, we first examine the soil fabric at the intra-aggregate scale. Then, we quantify the structural evolution of the soil using neutron tomography and link it to the macroscopic response of the soil. Based on the experimental evidence, the main features of the soil structure and its evolution are outlined for unsaturated aggregated soil under different loading conditions.