Effect of Swell–Shrink Cycles on Volumetric Behavior of Compacted Expansive Clay Stabilized Using Lime

In practice, it is quite common for soils to be mixed and compacted at moisture contents lower than the optimum moisture content (OMC) or lime content less than the optimum lime content (OLC). This study investigates the effect of not achieving the target of OMC or OLC on the volumetric behavior (swelling and shrinkage) and swelling pressure under swell–shrink cycles. The selected expansive clay was a residual soil derived from weathered Quaternary age basaltic rocks in Western Victoria, Australia. A series of cycles of swell–shrink tests were conducted at different initial lime contents, moisture contents, and stress levels. Vertical deformation and swell–shrink cycles' relationship were obtained and analyzed. The results showed that all specimens tested reached the equilibrium condition after the third swell–shrink cycle. The outcome of investigating the effect of not achieving the target of OLC showed that the maximum swelling occurred on the second cycle changing the degree of expansion from being moderate to very high expansive clay. This result recommended a review of current pavement design procedures to consider the cyclic swell–shrink potential to simulate the field condition for the longer term. However, for investigating the effect of not achieving the target of OMC, the results showed that the maximum swelling occurred at the first cycle, and this suggests that the effect of swell–shrink cycles could be neglected for the long term. This study also showed that at constant moisture content, the swelling pressure decreased as compaction stress decreased; however, at the constant compaction stress, the swelling pressure decreased as moisture content decreased.