Influence of microstructure on drying- and wetting-characteristics of fine-grained soils (original) (raw)
The importance of soil water retention characteristics (SWRCs) for understanding behaviour of soil in its unsaturated state has been acknowledged in recent years. However, the hysteresis associated with SWRCs poses difficulties in relating the water retention characteristics with unsaturated soil properties. During wetting and drying cycles, soil, depending on its properties, undergoes microstructural changes (namely mainly changes in pore sizes and their distribution) and these changes would affect the hysteresis. However, few studies have attempted to quantify or demonstrate this aspect. This study attempts to relate the soil microstructure changes (quantified by dominant pore diameter, d d) with the hysteresis associated with SWRCs (quantified by the slope of suction hysteresis, S ψh), by employing mercury intrusion porosimetry, MIP, for obtaining the pore size characteristics at initial slurried stage, end of drying cycle and end of wetting cycle for different soils. Efforts are also made to understand the influence of soil-specific parameters on pore size characteristics. The results indicate that S ψh and soil parameters such as clay content, specific surface area, cation exchange capacity and linear shrinkage are inversely proportional to d d in air dry state. Further, the study presents the quantification of differential volume changes during drying and wetting processes for different soils.