Assessing the effect of lime-zeolite on geotechnical properties and microstructure of reconstituted clay used as a subgrade soil

This study investigates the replacement of conventional stabilizers with eco-friendly alternatives, with a specific focus on enhancing pavement subgrade applications. This research aims to evaluate the impact of lime-zeolite treatment on the properties of clayey subgrades and its potential to outperform traditional stabilization methods. Various tests, such as Proctor compaction, Atterberg limits, swelling, and unconfined compressive strength (UCS), were performed considering the plasticity index variation. Optimal zeolite replacement led to significant improvements in the clayey soils' behavior. It reduced the plasticity index by up to 9.4% and almost eliminated swelling. Furthermore, unconfined compressive strength (UCS) values were enhanced by up to 7.56 times when compared to untreated soil. Ultrasonic pulse velocity (UPV) tests indicated substantial increases in primary wave velocity (Vp) and constrained modulus (Mv), reaching values of 2650 m/s and 9600 MPa, respectively, representing improvements of around 6.5 times and 50 times over untreated clay. The results highlight the remarkable efficacy of lime-zeolite substitution, particularly at a 25% replacement level. The improvements in plasticity, swelling, and strength characteristics signify the potential of this eco-friendly approach in pavement subgrade enhancement. The significant increases in UPV parameters provide insights into the improved structural integrity of the treated soils. This innovative approach offers valuable contributions to pavement subgrade design by addressing plasticity, swelling, and strength issues in clayey soils, ultimately leading to more sustainable and effective infrastructure projects.