Physicochemical and Microstructural Evaluation in Lime-Treated Silty Soil Exposed to Successive Wetting-Drying Cycles Submitted to Different Testing Conditions

Physicochemical and microstructural evolution in lime-treated soil subjected to successive wetting and drying (W-D) cycles was investigated, and the relevance of the laboratory-implemented testing condition with in situ conditions was discussed. Lime-treated soils were exposed to 17 W-D cycles using different testing conditions. Two laboratory testing conditions were operated at laboratory temperature, consisting of W-D duration representing the saturation level close to the one experienced in the in situ soil during rainy and drought periods. The results obtained were interpreted in terms of those obtained using a reference procedure from current standards, which involved oven-drying specimens at 71°C. Drying of lime-treated soil at 71°C reduced the water content from about 20% to 0.85%. This has led to greater contact between soil particles, thus increasing the suction from about 143.5 to 270 MPa. Such a phenomenon increased the unconfined compressive strength (UCS) of the oven-dried soil up to about three times compared with the air-dried specimen, although the available cementitious bonding, reflected by the presence of pores smaller than 3,000 Å, was comparatively low in the former compared with the latter. Percentage leaching of calcium components with respect to the initial calcium content of the soil was significantly low during W-D cycles due to greater exposure of only the outer part of the compacted soil structure during wetting. However, the leaching was comparatively higher in the oven-dried soil. The implemented wetting duration and drying temperature influenced the wetting front velocity of water, which significantly affects the duration taken by infiltered water to invade the core of an earthen structure, and hence its durability.