Salinity effect on the drying-induced mineralogical and microstructural evolution of lime-treated silty soil

In this study, the mineralogical and microstructural variations of lime-treated low-plasticity silty soil were investigated with emphasis on the combined effects of salinity and drying. Soil specimens with three different salinities were prepared using synthetic seawater, treated with 2% lime and cured for 90 days. Physicochemical analyses revealed that the carbonation rate of lime-treated soils decreased with increasing salinity. After drying, the CaCO3 content in the surface zone of specimens decreased from 2.5% for non-saline specimens to 1.1% for those with 6.76‰ salinity. Based on the mercury intrusion porosimetry (MIP), pore size distribution (PSD) curves were obtained at different water contents for three different salinities. Results showed that the PSD curves of lime-treated silty soils varied from bi-modal distribution in saturated state to tri-modal distribution at around 8% water content, and finally reverted to bi-modal pattern at around 3% with an appearance and disappearance of a nano-pore peak. The existence of sea salt contributed to the pore structure stability of lime-treated silty soil, providing evidence consistent with enhanced pozzolanic reactions. Nonetheless, the influence of salinity on pore structure was less significant than that of drying, particularly at low water content.