Effect of Granulated PVC and Zeolite Powder on Mechanical Properties of Lime-Stabilized Expansive Clay: Macro-Micro Analyses

This research investigates the efficacy of soil stabilization using two ecofriendly materials of zeolite powder and granulated polyvinyl chloride (PVC) for enhancing mechanical properties of lime-stabilized expansive soil. To this end, clay specimens are mixed with 5% lime which is incrementally substituted by zeolite powder while incorporating granular PVC up to 20%. Unconfined compressive strength (UCS) and indirect tensile strength (ITS) are primary assessed as the true measures of the strength properties. Following, swelling tests are conducted on samples containing optimal proportions of substitutional zeolite and granulated PVC to verify the effectiveness of the utilized additives in diminishing soil expansion. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) analyses are also carried out to provide credible micromechanical insights into the observed trends in macroscale experiments. Results indicate that substituting 25% of lime with zeolite powder yields the best performance of samples in terms of compressive strength, stiffness modulus, and swelling characteristics. Moreover, incorporation of 10% granulated PVC into the optimized samples led to the further enhancement in their strength and stiffness, providing a less brittle geocomposite material. The swelling tests also revealed that the synergistic effect of substitutional zeolite and PVC at their optimum percentages was appreciable in eliminating the swelling potential of expansive clay.