Effect of Moisture Hysteresis on the Resilient Modulus of Lime-Treated Expansive Clay

Several studies have asserted that seasonal moisture variation of unsaturated subgrade has a significant impact on its resilient modulus and, consequently, on the pavement performance and longevity. In regard to unsaturated lime-treated expansive subgrade, little research has addressed the influence of moisture variation on resilient modulus (M-R). In this context, this study aims at evaluating the effect of the drying and wetting cycle on the resilient behavior of lime-treated expansive clay at optimum lime conditions. Initially, the effects of lime content and curing period on the MR of lime-treated expansive clay were investigated to evaluate the optimum lime content. This involved conducting a series of repeated load tests under different lime contents and curing periods. In addition, a complementary series of tests were conducted to evaluate the unconfined compression strength along the same drying and wetting paths. Test data indicated that lime treatment resulted in a 370 % increase in the M-R after 28 days curing. On the other hand, the effect of the wetting and drying cycle, depicted as the relationship between MR and suction (or water content), showed a hysteresis phenomenon. Further examination of the MR along the drying path indicated a positive contribution of suction to the resilient behavior of lime-treated samples up to a specific suction value (>20 MPa), after which this contribution is considered negligible. Hysteresis phenomenon was also observed for unconfined compression strength because of wetting and drying; however, with a different trend. The discrepancy between hysteresis trends were attributed to differences in loading characteristics.