Effects of aggregate size on water retention capacity and microstructure of lime-treated silty soil

Lime treatment is a common technique of improving the workability and geotechnical properties of soils. In this study, the aggregate size effects on the water retention capacity and microstructure of lime-treated soil were investigated. Two soil powders with different maximum aggregate sizes (D-max = 0.4 and 5 mm) were prepared and stabilised by 2% lime (by weight of dry soil). Soil samples were prepared by compaction at dry side of optimum water content (w = 17%) with a dry density of 1.65 Mg/m(3). Suction and pore size distribution were determined after different curing periods. The results obtained show that: (a) the treated soil with smaller D-max presents relatively smaller modal sizes and lower frequency of macropores (10-330 mu m); (b) lime addition effectively improves the soil water retention capacity and decreases both the modal sizes of macro-and micropores gradually over time. Moreover, a higher air entry value and larger water retention capacity were also observed for a smaller D-max value, in agreement with the pore size distributions.