Effect of compaction condition on the water retention capacity, microstructure and its evolution during drying of compacted loess

Abstract

To investigate the initial microstructure and water retention capacity of compacted loess molded under different compaction energy, the soil–water characteristic curves (SWCCs) and pore-size distribution curves (PSDs) of compacted loess specimens with different molding water contents or compaction energies were determined. Moreover, the PSDs of compacted loess specimens dried to different suctions were measured and the fractal dimensions of these specimens were examined to explore the microstructural evolution of compacted loess during drying. The results show that molding water content mainly affects the densities of macropores and mesopores, and compaction energy only affects the density of macropores. As the molding water content range of 16% to 20%, the AEV decreases with the increase of molding water content. The specimen with a lower molding water content has a larger slope of SWCC (or desorption rate). Compaction energy influences the water retention capacity of compacted loess in the low suction range (< 30 kPa). In response to suction increase, the PSD of compacted loess changes a little, while the fractal dimension increases with suction and there is a good linear relationship between them, indicating that the roughness of the pore surfaces is increasing during drying. This study provides new insight into the relationship between water retention capacity and pore structure of compacted loess and the microstructural evolution of compacted loess during drying, which is meaningful to the prevention of loess geological hazards.