The Influence of Different Curing Conditions on Durability of Lime-Stabilized Clay Soils (Micro- and Macro- Structure Study)

Clay soils have generally appropriate strength and stiffness in dried conditions. However, their strength parameters such as bearing capacity, unconfined compression strength, and shear strength, are reduced, and compressibility and settlements are increased significantly in the presence of water. In various civil engineering projects, clay soils, especially soft clays, are usually stabilized by using lime. In this research, kaolinite clay samples were stabilized using 0, 10, 15 and 20 percent by weight of lime at temperature of 27 ºC and relative humidity of 98±2 percent. Three series of samples were studied: the first series after 14 days curing, the second series after 28 days curing, and the third series were submerged in water 14 days after curing and then were tested. For macro-structure study, the specimens were tested under unconfined compressive strength test, and for micro-structure studies, and due to cementation of soil-lime-reaction, X-ray Diffraction (XRD) analysis, Scanning Electron Microscope (SEM), and Energy Dispersive X-Ray Spectroscopy (EDS or EDX) were carried out. Results showed that using 10% lime in samples with 14 days curing time and submerged in water for 14 days have 65% lower strengths in comparison with the samples cured for 28 days. This was due to the infiltration of water and breaking and weakening of strength of cementation compounds. Also, for both macro and micro structure studies, optimum lime content is 10% in order to reach the proper soil strength.