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

Abstract

Abstract 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 (MR). 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 MR 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.